View Filing Data

Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2017 shares
Document and Entity Information [Abstract]
Entity Registrant Name	AC Immune SA
Entity Central Index Key	0001651625
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding	57,355,188
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

Balance Sheets SFr in Thousands, $ in Thousands	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2016 CHF (SFr)
Non-current assets
Property, plant and equipment	SFr 2,353	SFr 1,120
Financial assets	126	86
Total non-current assets	2,479	1,206
Current assets
Prepaid expenses	1,440	1,278
Accrued income	2,799	889
Other current receivables	918	517
Cash and cash equivalents	124,377	152,210
Total current assets	129,534	154,894
Total assets	132,013	156,100
Shareholders' equity
Share capital	1,147	1,135
Share premium	188,299	188,166
Accumulated losses	(72,607)	(46,921)
Total shareholders' equity	116,839	142,380
Non-current liabilities
Accrued interest - long-term	99	0
Long-term financing obligation	395	0
Net employee defined benefit liabilities	4,926	3,798
Total non-current liabilities	5,420	3,798
Current liabilities
Trade payables and other payables	1,092	4,035
Accrued expenses	8,307	5,366
Deferred income	355	521
Total current liabilities	9,754	9,922
Total liabilities	15,174	13,720
Total shareholders' equity and liabilities	SFr 132,013	SFr 156,100

Statements of Income / (Loss) - CHF (SFr) SFr in Thousands	12 Months Ended
Statements of Income / (Loss) - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue
Contract revenue	SFr 20,255	SFr 23,214	SFr 39,090
Total revenue	20,255	23,214	39,090
Operating expenses
Research and development expenses	(32,663)	(25,774)	(17,049)
General and administrative expenses	(10,131)	(7,896)	(3,417)
Total operating expenses	(42,794)	(33,670)	(20,466)
Operating income / (loss)	(22,539)	(10,456)	18,624
Finance income / (expense), net	(4,055)	3,324	1,591
Interest income	330	43	55
Interest expense	(147)	(7)	0
Finance result, net	(3,872)	3,360	1,646
Income / (loss) before tax	(26,411)	(7,096)	20,270
Income tax expense	0	0	0
Income / (loss) for the period	SFr (26,411)	SFr (7,096)	SFr 20,270
Earnings / (loss) per share (EPS):
Basic, income / (loss) for the period attributable to equity holders (in CHF per share)	SFr (0.46)	SFr (0.14)	SFr 0.47
Diluted, income / (loss) for the period attributable to equity holders (in CHF per share)	SFr (0.46)	SFr (0.14)	SFr 0.44
Weighted-average number of shares used to compute EPS basic (in shares)	57,084,295	50,096,859	43,412,250
Weighted-average number of shares used to compute EPS fully diluted (in shares)	57,084,295	50,096,859	46,043,198

Statements of Comprehensive Income / (Loss) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statements of Comprehensive Income / (Loss) [Abstract]
Income / (loss) for the period	SFr (26,411)	SFr (7,096)	SFr 20,270
Other comprehensive income / (loss) not to be reclassified to income or loss in subsequent periods (net of tax)
- Re-measurement losses on defined benefit plans (net of tax of CHF 0 for all periods)	(780)	(761)	(736)
Total comprehensive income / (loss), net of tax	SFr (27,191)	SFr (7,857)	SFr 19,534

Statements of Comprehensive Income / (Loss) (Parenthetical) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other comprehensive income / (loss) not to be reclassified to income or loss in subsequent periods (net of tax)
Income tax expense	SFr 0	SFr 0	SFr 0

Statements of Changes in Equity - CHF (SFr) SFr in Thousands	Total	Share Capital [Member]	Share Premium [Member]	Accumulated Losses [Member]
Balance, beginning of period at Dec. 31, 2014	SFr 23,467	SFr 854	SFr 83,068	SFr (60,455)
Net income / (loss) for the period	20,270	0	0	20,270
Other comprehensive loss	(736)	0	0	(736)
Total comprehensive income / (loss), net of tax	19,534	0	0	19,534
Share-based payments	540	0	0	540
Issuance of preferred Series E shares	29,499	62	29,437	0
Proceeds from IPO net of underwriting fees	0
Issuance of shares:
Exercise of options	142	12	130	0
Transaction costs	(2,139)	0	(2,139)	0
Balance, end of period at Dec. 31, 2015	71,043	928	110,496	(40,381)
Net income / (loss) for the period	(7,096)	0	0	(7,096)
Other comprehensive loss	(761)	0	0	(761)
Total comprehensive income / (loss), net of tax	(7,857)	0	0	(7,857)
Share-based payments	1,317	0	0	1,317
Preferred Series E extension shares	13,205	28	13,177	0
Proceeds from IPO net of underwriting fees	69,388	138	69,250	0
Issuance of shares:
Exercise of options	301	41	260	0
Transaction costs	(5,017)	0	(5,017)	0
Balance, end of period at Dec. 31, 2016	142,380	1,135	188,166	(46,921)
Net income / (loss) for the period	(26,411)	0	0	(26,411)
Other comprehensive loss	(780)	0	0	(780)
Total comprehensive income / (loss), net of tax	(27,191)	0	0	(27,191)
Share-based payments	1,579	0	0	1,579
Proceeds from IPO net of underwriting fees	0
Issuance of shares:
Restricted Share Awards	0	0	74	(74)
Exercise of options	71	12	59	0
Balance, end of period at Dec. 31, 2017	SFr 116,839	SFr 1,147	SFr 188,299	SFr 72,607

Statements of Cash Flows - CHF (SFr) SFr in Thousands	12 Months Ended
Statements of Cash Flows - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Income / (loss) for the period	SFr (26,411)	SFr (7,096)	SFr 20,270
Adjustments to reconcile net income for the period to net cash flows:
Depreciation of property, plant and equipment	580	278	287
Finance result, net	3,872	(3,360)	(1,646)
Share-based compensation expense	1,579	1,317	540
Changes in pensions	348	250	(359)
Accrued interest on long-term debt	99	0	0
Changes in working capital:
Prepaid expenses	(162)	(494)	(2,135)
Accrued income	(1,910)	(842)	6
Other current receivables	(401)	(248)	25,666
Accrued expenses	2,940	1,564	1,707
Deferral of unearned revenue	(156)	476	(160)
Long-term financing obligation	204	0	0
Accounts payable	(2,853)	2,592	(141)
Cash provided by/(used in) operating activities	(22,271)	(5,563)	44,035
Interest income	330	43	55
Finance costs	(153)	(126)	(6)
Net cash flows provided by/(used in) operating activities	(22,094)	(5,646)	44,084
Investing activities
Purchases of property, plant and equipment	(1,802)	(899)	(244)
Rent deposit	(40)	0	0
Net cash flows used in investing activities	(1,842)	(899)	(244)
Financing activities
Proceeds from issuance of preferred Series E	0	13,206	29,499
Proceeds from issuance of common shares	0	69,388	0
Transaction costs of issue of shares	0	(4,105)	(1,859)
Proceeds from issuance of shares-option plans	71	301	83
Proceeds from long-term debt	200	0	0
Proceeds from employee loan repayments	0	0	55
Net cash flows provided by financing activities	271	78,790	27,778
Net increase / (decrease) in cash and cash equivalents	(23,665)	72,245	71,618
Cash and cash equivalents, beginning of period	152,210	76,522	3,306
Exchange gains on cash and cash equivalents	(4,168)	3,443	1,598
Cash and cash equivalents, end of period	124,377	152,210	76,522
Net increase / (decrease) in cash and cash equivalents	SFr (23,665)	SFr 72,245	SFr 71,618

Statements of Cash Flows (Parenthetical) SFr in Millions	12 Months Ended
Statements of Cash Flows (Parenthetical) SFr in Millions	Dec. 31, 2016 CHF (SFr)
Financing activities
Underwriting fees	SFr 5.1

General information

12 Months Ended

Dec. 31, 2017

General information [Abstract]

General information

1.	General information

AC Immune SA (the “Company,” or “AC Immune,” “ACI,” “we,” “our,” “ours,” “us”) is a clinical stage biopharmaceutical company leveraging our two proprietary technology platforms to discover, design and develop novel, proprietary medicines for prevention, diagnosis and treatment of neurodegenerative diseases associated with protein misfolding. Misfolded proteins are generally recognized as the leading cause of neurodegenerative diseases, such as Alzheimer’s disease, or AD, and Parkinson’s disease, or PD, with common mechanisms and drug targets, such as Abeta, Tau and alpha-synuclein. Our corporate strategy is founded upon a three-pillar approach that targets Alzheimer’s disease, non-Alzheimer’s neurodegenerative diseases including neuro-orphan indications and diagnostics. Our lead product candidate is crenezumab, a humanized, monoclonal, conformation-specific anti-Abeta antibody that we developed using our proprietary SupraAntigen platform. The two Phase 3 clinical studies for crenezumab were commenced in early 2016 and in February 2017, respectively. We use our two unique proprietary platform technologies, SupraAntigen (conformation-specific biologics) and Morphomer (conformation-specific small molecules), to discover, design and develop medicines and diagnostics to target misfolded proteins.

The Company was initially incorporated as a limited liability company on February 13, 2003 in Basel and effective August 25, 2003 was transitioned into a stock company. The Company’s corporate headquarters are located at EPFL Innovation Park Building B, Ecublens/Lausanne, Vaud, Switzerland.

Basis of preparation

12 Months Ended

Dec. 31, 2017

Basis of preparation [Abstract]

Basis of preparation

2.	Basis of preparation

Going concern

The financial statements have been prepared on the basis that the Company will continue as a going concern after considering the Company’s cash position of CHF 124.4 million as of December 31, 2017. The Company received CHF 14 million in 2017 for the clinical milestone related to the collaboration with Genentech on the first dosing in a Phase 2 clinical trial for Alzheimer’s Disease (AD) with an anti-Tau monoclonal antibody, CHF 14 million in 2016 for the clinical milestone related to the collaboration with Genentech on the anti-Tau antibody program and CHF 4.9 million in 2016 for the clinical milestone related to ACI-35 pursuant to its collaboration with Janssen. This total also reflects the $75.9 million (CHF 74.5 million) in gross proceeds raised in the initial public offering (“IPO”) in September 2016 and the $13.5 million (CHF 13.2 million) the Company raised in the Series E Private Placement Extension financing in April 2016.

To date, the Company has financed its cash requirements primarily from its initial public offering, share issuances and revenues from collaboration agreements. The Company is a clinical stage company and is exposed to all the risks inherent to establishing a business. Inherent to the Company’s business are various risks and uncertainties, including the substantial uncertainty as to whether current projects will succeed. The Company’s success may depend in part upon its ability to (i) establish and maintain a strong patent position and protection, (ii) enter into collaborations with partners in the biotech and pharmaceutical industry, (iii) successfully move its product candidates through clinical development, (iv) attract and retain key personnel, and (v) acquire capital to support its operations.

Statement of compliance

The financial statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). These financial statements have been approved for issue by the Board of Directors on March 20, 2018.

Basis of measurement

The financial statements have been prepared under the historical cost convention except for items that are required to be accounted for at fair value.

Functional currency

The financial statements of the Company are presented in Swiss Francs (CHF), which is also the functional currency of the Company. All financial information presented in Swiss Francs (except for share capital and earnings per share data) has been rounded to the nearest thousand CHF (CHF thousands), unless otherwise indicated. The Company also has transactions denominated in U.S. Dollars ($) and Euros (EUR) that are translated to CHF using prevailing exchange rates at the date of transaction or as of the balance sheet date.

Summary of significant accounting policies

12 Months Ended

Dec. 31, 2017

Summary of significant accounting policies [Abstract]

Summary of significant accounting policies

3.	Summary of significant accounting policies

The principal accounting policies adopted in the preparation of these financial statements are set out below. These policies have been consistently applied to all the years presented, unless otherwise stated.

Current vs. non-current classification

The Company presents assets and liabilities in the balance sheet based on current/non-current classification. The Company classifies all amounts to be realized or settled within twelve months after the reporting period to be current and all other amounts to be non-current.

Foreign currency transactions

Foreign currency transactions are translated into the functional currency Swiss Francs (CHF) using prevailing exchange rates at the dates of the transactions. Monetary assets and liabilities denominated in foreign currencies are translated into CHF at rates of exchange prevailing at reporting date. Any gains or losses from these translations are included in the statement of income in the period in which they arise.

Revenue recognition

Revenue includes upfront fees, milestone payments as well as revenue from research and development agreements associated with collaborations with third parties and grants from public institutions and foundations.

License of intellectual property

Revenue from non-refundable, upfront license payments and performance milestones where the Company has continuing involvement is recognized over the estimated performance or agreement period, depending on the terms of the agreement. The recognition of revenue is prospectively changed for subsequent changes in the development or agreement period.

For collaboration agreements on product candidates (i) that are in clinical development, (ii) where the upfront payment reflects a payment for past investments the Company has made in the development of the product candidate, access to the product candidate, the associated intellectual property and our knowledge, and, (iii) where there is no further performance commitment, the Company recognizes the fair value of the upfront payment at the time of entering into the collaboration agreement. For collaboration agreements (i) in clinical development but where conditions (ii) and (iii) are not met, the Company recognizes revenue from upfront payments under our collaboration agreements pro-rata over the term of the estimated period of performance under each agreement.

For collaboration agreements, in addition to receiving upfront payments, the Company is also entitled to milestone and other contingent payments upon achieving pre-defined objectives.

Milestone payments

Revenue from milestones, if they are non-refundable and deemed substantive, is recognized upon successful accomplishment of the milestones. To the extent that non-substantive milestones are achieved and the Company has remaining performance obligations, milestones are deferred and recognized as revenue over the estimated remaining period of performance.

Research and Development Services

The Company has certain arrangements with our collaboration partners that include contracting our full-time employees for research and development programs. These revenues are recorded in contract revenue as the services are performed.

Research and development expenditure

Given the stage of development of the Company’s products, all research expenditure is recognized as expense when incurred. Research and development expenditures include:

the cost of acquiring, developing and manufacturing active pharmaceutical ingredients for product candidates that have not received regulatory approval, clinical trial materials and other research and development materials;

fees and expenses incurred under agreements with contract research organizations, investigative sites, and other entities in connection with the conduct of clinical trials and preclinical studies and related services, such as administrative, data management, and laboratory services;

fees and costs related to regulatory filings and activities;

costs associated with pre-clinical and clinical activities; and

employee-related expenses, including salaries and bonuses, benefits, travel and stock-based compensation expense

For external research contracts the “stage of completion” method is used to estimate the amount of accrued expense related to the research projects for its clinical studies. The Company estimates its accrued expenses as of the balance sheet date in the financial statement based on facts and circumstances known at the time.

Registration costs for patents are part of the expenditure for research and development projects. Therefore, registration costs for patents are expensed when incurred as long as the research and development project concerned does not meet the criteria for capitalization.

Property, plant and equipment

Equipment is shown at historical acquisition cost, less accumulated depreciation and any accumulated impairment losses. Historical costs include expenditures that are directly attributable to the acquisition of the property, plant and equipment. Depreciation is calculated using a straight-line method to write off the cost of each asset to its residual value over its estimated useful life as follows:

IT equipment	3 years
Laboratory equipment	5 years
Leasehold improvements / furniture	5 years

The assets’ residual values and useful lives are reviewed, and adjusted if appropriate, at each balance sheet date. Where an asset’s carrying amount is greater than its estimated recoverable amount, it is written down to its recoverable amount.

Gains and losses on disposals are determined by comparing the disposal proceeds with the carrying amount and are included in the Statements of Income / (Loss).

Financial assets and liabilities

The Company’s financial assets and liabilities are comprised of receivables, cash and cash equivalents, trade payables and a long-term financing obligation. The carrying amount for these financial assets and liabilities approximates fair value.

Receivables

Receivables are non-derivative financial assets with fixed payments that are not quoted in an active market. They arise when the Company provides money, goods or services directly to a debtor with no intention of trading the receivable. They are included in current assets, except for those with maturities greater than 12 months after the balance sheet date, which are classified as long-term assets. Receivables are recognized at their billing value. An allowance for doubtful accounts is recorded for potential estimated losses when there is objective evidence of the debtor’s inability to make required payments.

Cash and cash equivalents

Cash and cash equivalents include deposits held with external financial institutions and cash on hand. All cash and cash equivalents are either in cash or in deposits with less than 3 months’ duration.

The Company assesses at each period whether there is objective evidence that financial assets are impaired. Recognized impairment losses would be immediately recognized in the Statement of Income / (Loss).

Trade payables

Trade payables are recognized initially at fair value, which represents cost incurred.

Long-term financing obligation

The Company’s long-term financing obligation is measured as of the period end date based on the repayment terms when originated.

Share capital and Initial Public Offering

Ordinary (Common) Shares are classified as equity, as were all Preferred Shares previously outstanding prior to the IPO. Expenses directly attributable to the issuance of new shares are shown in equity as a deduction, net of tax, from the proceeds.

Preferred Shares

AC Immune had five classes (Class A, B, C, D and E) of Preferred Shares outstanding as of December 31, 2015. These Preferred Shares remained outstanding until the Company completed an IPO in September 2016 and at that time the Preferred Shares were converted to Common Shares on a one-for-one basis. The Preferred Shares were a class of shares that AC Immune SA issued in connection with five separate capital increases and conveyed voting rights and certain other rights to their holders.

The holders of Preferred Shares owned 80.1% of the total amount of shares outstanding (assuming conversion of the Preferred Shares into Common Shares on a one-for-one basis) as of December 31, 2015 and the Company’s Board of Directors were predominantly the holders of Preferred Shares. The Preferred Shares had been the primary source of equity financing for the Company for more than 13 years until the Company completed an IPO in September 2016, at which point all Preferred Shares were converted to Common Shares. The Preferred Shares did not have mandatory redemption features; however, the Shareholders’ Agreement provided for conversion of Preferred Shares into Common Shares as a result of an IPO. The redemption of the Preferred Shares was authorized by the Company’s Board of Directors.

The voting rights associated with Preferred Shares were the same as for Common Shares. Each Preferred Share entitled the holder to one vote. No dividends were paid on the Preferred Shares and the holders of Preferred Shares were not entitled to any dividends unless dividends are paid on the Common Shares.

The Preferred Shares had a liquidation preference wherein, in the event of a change of control or a liquidation of the Company, the holders of Preferred Shares were entitled to receive, prior and in preference to the holders of Common Shares, the amount corresponding to the price paid for each Preferred Share. Thereafter, all holders of Preferred Shares participated with the holders of Common Shares on an as-if-converted basis in any remaining proceeds.

On October 23, 2015, AC Immune completed a 250-for-1 stock split. The split was applied to all of AC Immune’s outstanding common shares, preferred shares (Series A, B, C, D and E) and vested and unvested options. The stock split impacted earnings per share (“EPS”). To facilitate a comparison of EPS figures, the 2015 reported EPS figures were adjusted to reflect the stock split. 2015 disclosures in notes 9 (share capital), 18 (share-based compensation) and 20 (earnings per share) have all been prepared taking into consideration the 250-for-1 stock split.

On April 15, 2016, AC Immune completed a private placement of Series E preferred shares, each with a nominal value of CHF 0.02 per share (the “Series E Private Placement Extension”). An aggregate 1,401,792 Series E preferred shares were issued at a price of $9.6384 per preferred share to certain strategic investors, individuals and existing shareholder in the Series E Private Placement Extension for an aggregate subscription amount of approximately $13.5 million. The Series E preferred shares had substantially the same terms as the Series A, B, C and D preferred shares and were accounted for as equity on AC Immune’s balance sheet and subsequently converted to Common Shares as a result of the IPO.

Initial Public Offering (IPO)

On September 22, 2016, AC Immune successfully priced a 6.0 million common share IPO at $11.00 per share. On the same day, the underwriters exercised the overallotment option which resulted in a further 900,000 common shares being placed in the market and took the total number of shares offered to investors to 6.9 million common shares. The gross proceeds received were $75.9 million (CHF 74.5 million) while the proceeds net of underwriting fees amounted to $70.6 million (CHF 69.3 million).

The IPO resulted in an increase of CHF 64.2 million in the share premium of AC Immune excluding the effect of transaction costs associated with the IPO related to the issuance of new shares. Transaction costs associated with the IPO and related to the issuance of new shares were charged directly against the share premium account thereby reducing the total equity reported.

Employee benefits

Post-employment benefits

The Company operates the mandatory pension schemes for its employees in Switzerland. The schemes are generally funded through payments to insurance companies or trustee-administered funds. The Company has a pension plan designed to pay pensions based on accumulated contributions on individual savings accounts. However, this plan is classified as a defined benefit plan under IAS 19.

The net defined benefit liability is the present value of the defined benefit obligation at the balance sheet date minus the fair value of plan assets. The defined benefit obligation is in all material cases calculated annually by independent actuaries using the projected unit credit method, which reflects services rendered by employees to the date of valuation, incorporates assumptions concerning employees’ projected salaries, pension increases as well as discount rates of highly liquid corporate bonds which have terms to maturity approximating the terms of the related liability.

Remeasurements of the net defined benefit liability, which comprise actuarial gains and losses, the return on plan assets (excluding interest), are recognized immediately in Other Comprehensive Income. Past service costs, including curtailment gains or losses, are recognized immediately in general and administrative expenses within the operating results. Settlement gains or losses are recognized in general and administrative expenses within the operating results. The Company determines the net interest expense (income) on the net defined benefit liability for the period by applying the discount rate used to measure the defined benefit obligation at the beginning of the annual period or in case of any significant events between measurement dates to the then-net defined benefit liability, taking into account any changes in the net defined benefit liability during the period as a result of contributions and benefit payments. Net interest expense and other expenses related to defined benefit plans are recognized in the statement of income.

Share-based compensation

The Company operates an equity-settled, share-based compensation plan. The fair value of the employee services received in exchange for the grant of equity based awards is recognized as an expense. The total amount to be expensed over the vesting period is determined by reference to the fair value of the instruments granted, excluding the impact of any non-market vesting conditions. Non-market vesting conditions are included in assumptions about the number of instruments that are expected to become exercisable. At each balance sheet date, the Company revises its estimates of the number of instruments that are expected to become exercisable. It recognizes the impact of the revision of original estimates, if any, prospectively in the income statement, and a corresponding adjustment to equity over the remaining vesting period.

Stock options granted under the Company’s stock option plans A, B, C and the 2016 Stock Option and Incentive Plan are valued using the Black-Scholes option pricing model (see Note 18). This valuation model as well as parameters used such as expected volatility and expected term of the stock options are partially based on management’s estimates.

The proceeds received net of any directly attributable transaction costs are credited to share capital (nominal value) and share premium when the options are exercised.

We estimate the fair value of non-vested stock awards (restricted shares and restricted share units) using a reasonable estimate of market value of the common stock on the date of the award. We classify our share-based payments as equity-classified awards as they are settled in shares of our common stock. We measure equity-classified awards at their grant date fair value and do not subsequently remeasure them. Compensation costs related to equity-classified awards are equal to the fair value of the award at grant-date amortized over the vesting period of the award using the graded method. We reclassify that portion of vested awards to share premium as the awards vest.

Provisions

Provisions are recognized when the Company has a present legal or constructive obligation as a result of past events where it is more likely than not that an outflow of resources will be required to settle the obligation, and a reliable estimate of the amount can be made.

Taxation

Current income tax assets and liabilities for the period are measured at the amount expected to be recovered from or paid to the taxation authorities. The tax rates and tax laws used to compute the tax amounts are those that are enacted or substantively enacted, at the reporting date in accordance with the fiscal regulations of the respective country where the Company operates and generates taxable income. Deferred tax is provided using the liability method on temporary differences between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes at the reporting date.

Deferred tax assets and liabilities are measured at the tax rates that are expected to apply in the year when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted at the reporting date. If required, deferred taxation is provided in full using the liability method, on all temporary differences at the reporting dates. It is calculated at the tax rates that are expected to apply to the period when it is anticipated the liabilities will be settled, and it is based on tax rates (and laws) that have been enacted or substantively enacted at the reporting date.

Deferred income tax assets are recognized to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. Deferred tax assets are reviewed at each reporting date and are reduced to the extent that it is no longer probable that the related tax benefit will be realized. Although the Company has substantial tax loss carryforwards, historically, due to the fact that the Company had limited certainty on the achievement of key milestones, it has not recognized any deferred tax assets.

Earnings per share

The Company presents basic earnings per share for each period in the financial statements. The earnings per share is calculated by dividing the earnings of the period by the weighted average number of shares (common and preferred) outstanding during the period. Diluted earnings per share reflect the potential dilution that could occur if dilutive securities such as share options were vested or exercised into common shares or resulted in the issuance of common shares that would participate in net income. Anti-dilutive shares are excluded from basic and dilutive earnings per share calculation.

Critical judgments and accounting estimates

The preparation of financial statements in conformity with IFRS requires management to make judgments, estimates and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, income and expenses.

The areas where AC Immune has had to make judgments, estimates and assumptions relate to (i) revenue recognition on collaboration and licensing agreements, (ii) clinical development accruals, (iii) net employee defined benefit liability, (iv) income taxes and (v) share-based compensation. Actual results may differ from these estimates. Estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognized in the period in which the estimates are revised and in any future periods affected.

Income taxes

As disclosed in Note 16, the Company has tax losses that can generally be carried forward for a period of 7 years from the period the loss was incurred. These tax losses represent potential value to the Company to the extent that the Company is able to create taxable profits before the expiry period of these tax losses. The Company has not recorded any deferred tax assets in relation to these tax losses.

Preferred shares

Significant judgment was required in determining the classification of the Preferred Shares issued by the Company as either equity or liabilities. The Preferred shareholders received certain preference rights that represented a significant proportion of the net assets of the Company in the case of liquidation or certain exit events, the occurrence of which was outside the control of the Company. These Preferred Shares remained outstanding until the Company completed an IPO in September 2016 and at that time the Preferred Shares were converted from Preferred Shares to Common Shares on a one-for-one basis.

Segment reporting

The Company has one segment. The Company currently focuses all of its resources on discovering and developing therapeutic and diagnostic products targeting misfolded proteins.

The Company is managed and operated as one business. A single management team that reports to the chief operating decision maker comprehensively manages the entire business. Accordingly, the Company views its business and manages its operations as one reportable segment. Non-current assets are located in and revenue is attributable to the Company’s country of domicile, Switzerland.

Accounting pronouncements – not yet adopted

IFRS 9 Financial Instruments will supersede IAS 39 Financial Instruments: Recognition and Measurement and is effective for annual periods beginning on or after January 1, 2018. IFRS 9 covers classification and measurement of financial assets and financial liabilities, impairment of financial assets and hedge accounting. The Company expects to adopt this standard on January 1, 2018, and after completing its assessment of the standard, AC Immune does not anticipate IFRS 9 to have a material impact on the financial statements.

IFRS 16 Leases provides a new model for lessee accounting in which all leases, other than short-term and small-ticket-item leases, will be accounted for by the recognition on the balance sheet of a right-to-use asset and a lease liability, and the subsequent amortization of the right-to-use asset over the lease term. IFRS 16 will be effective for annual periods beginning on or after January 1, 2019 with early adoption permitted. AC Immune is still assessing the impact of this standard on its financial statements.

The Company has completed its analysis of the impact of IFRS 15 Revenue from Contracts with Customers, which amends revenue recognition requirements and establishes principles for reporting information about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The standard replaces IAS 18 Revenue and IAS 11 Construction Contracts and Related Interpretations. The new standard, as amended, becomes effective for the Company in the first quarter of fiscal year 2018, but allows the Company to adopt early. The Company will adopt this accounting standard in the first quarter of fiscal year 2018.

The Company will adopt this standard using the modified retrospective method. Under this method, the cumulative effect of adopting the standard will be recorded to retained earnings on January 1, 2018. We have completed our assessment of the effect of this adoption, including a detailed review of all of our contracts to identify potential differences in accounting as a result of the new standard and use of the practical expedient regarding contract modifications. The new standard will result in additional revenue-related disclosures in the footnotes to our financial statements. Adoption of this standard will also require changes to certain business processes which are in place to ensure our compliance. Based on our analysis, we do not anticipate a material impact on our total revenues or costs.

Property, plant and equipment

12 Months Ended

Dec. 31, 2017

Property, plant and equipment [Abstract]

Property, plant and equipment

4.	Property, plant and equipment

	As of December 31, 2017
	Furniture			Computers/IT			Lab Equipment			Leasehold Improvements			Total
Acquisition Cost:
Balance at the end of the previous year		81			298			2,792			103			3,274
Acquisitions		4			271			1,369			169			1,813
Balance at end		85			569			4,161			272			5,087

Accumulated depreciation:
Balance at the end of the previous year		(45	)		(172	)		(1,858	)		(79	)		(2,154	)
Depreciation expense		(14	)		(87	)		(453	)		(26	)		(580	)
Balance at end		(59	)		(259	)		(2,311	)		(105	)		(2,734	)

Carrying Amount:
December 31, 2016		36			126			934			24			1,120
December 31, 2017		26			310			1,850			167			2,353

	As of December 31, 2016
	Furniture			Computers/IT			Lab Equipment			Leasehold Improvements			Total
Acquisition Cost:
Balance at the end of the previous year		43			172			2,058			103			2,376
Acquisitions		38			126			734			-			898
Balance at end		81			298			2,792			103			3,274

Accumulated depreciation:
Balance at the end of the previous year		(36	)		(138	)		(1,629	)		(73	)		(1,876	)
Depreciation expense		(9	)		(34	)		(229	)		(6	)		(278	)
Balance at end		(45	)		(172	)		(1,858	)		(79	)		(2,154	)

Carrying Amount:
December 31, 2015		7			34			429			30			500
December 31, 2016		36			126			934			24			1,120

For the years ended December 31, 2017, 2016 and 2015, the Company incurred CHF 580 thousand, 278 thousand and 287 thousand in depreciation expense, respectively.

Financial Assets

12 Months Ended

Dec. 31, 2017

Financial Assets [Abstract]

Financial Assets

5.	Financial Assets

AC Immune has two deposits in escrow accounts totaling CHF 126 thousand associated with the lease of the Company’s premises as of December 31, 2017 and CHF 86 thousand as of December 31, 2016.

Prepaid expenses and accrued income

12 Months Ended

Dec. 31, 2017

Prepaid expenses and accrued income [Abstract]

Prepaid expenses and accrued income

6.	Prepaid expenses and accrued income

	For the Years Ended December 31,
in CHF thousands	2017	2016
Prepaid expenses	1,440	1,278
Accrued income	2,799	889
Total	4,239	2,167

The prepaid expenses relate mainly to research contracts with down-payments at contract signature and the related activities will start or continue into 2018.

Accrued income consists of CHF 1.5 million as of December 31, 2017 associated with our Biogen collaboration and CHF 1.2 million associated with our Janssen collaboration (see Note 13). CHF 0.9 million was accrued as of December 31, 2016 and subsequently invoiced in 2017.

Other current receivables

12 Months Ended

Dec. 31, 2017

Other current receivables [Abstract]

Other current receivables

7.	Other current receivables

	For the Years Ended December 31,
in CHF thousands	2017		2016
Other receivables		691		182
Swiss VAT		112		320
Withholding tax		115		15
Total		918		517

The maturity of these assets is less than three months. The Company considers the counterparty risk as low and the carrying amount of these receivables is considered to correspond to their fair value.

Cash and cash equivalents

12 Months Ended

Dec. 31, 2017

Cash and cash equivalents [Abstract]

Cash and cash equivalents

8.	Cash and cash equivalents

	For the Years Ended December 31,
in CHF thousands	2017		2016
Cash		124,377		152,210
Total		124,377		152,210

By Currency
CHF		103,272		41,322
EUR		3,658		6,727
USD		17,447		104,161
Total		124,377		152,210

At the balance sheet dates, Company funds were held in CHF, EUR and USD currencies. As of December 31, 2017, funds in EUR and USD were translated into CHF at a rate of 1.169 and 0.976, respectively.

Share capital

12 Months Ended

Dec. 31, 2017

Share capital [Abstract]

Share capital

9.	Share capital

As of December 31, 2017 and 2016, the issued share capital amounted to CHF 1,147,104 and CHF 1,135,468 respectively and comprised of Common Shares of 57,355,188 and 56,773,392, respectively.

The table below summarizes the Company’s capital structure:

	For the Years Ended December 31,
	2017		2016
	Number	CHF	Number	CHF
Common shares with a nominal value of CHF 0.02 each	57,355,188	1,147,104	56,773,392	1,135,468
Total	57,355,188	1,147,104	56,773,392	1,135,468

The Common Shares nominal values of CHF 0.02 per share are fully paid in.

The changes in common shares outstanding for the year ended December 31, 2017 represent 4,023 Restricted Shares issued, 5,998 Restricted Share Units which vested and 571,775 share options that were exercised.

On April 15, 2016, AC Immune completed a private placement of Series E preferred shares, each with a nominal value of CHF 0.02 per share (the “Series E Private Placement Extension”). An aggregate 1,401,792 Series E preferred shares were issued at a price of $9.6384 per preferred share to certain strategic investors, individuals and existing shareholder in the Series E Private Placement Extension for an aggregate subscription amount of approximately $13.5 million. As previously referenced in Note 3 in the summary of significant accounting policies, all outstanding Preferred Shares were converted to common shares as a result of the IPO completed in September 2016.

The changes in common shares outstanding for the year ended December 31, 2016 represent (i) 6.9 million common shares issued as a result of the Company’s 2016 IPO, (ii) 38,577,042 additional common shares as a result the conversion of all outstanding preferred shares (including the 1.4 million preferred Series E shares issued in April 2016) on a one-for-one basis as a result of the Company’s 2016 IPO and (iii) 2,069,100 share options exercised during 2016.

Trade payables and accrued liabilities

12 Months Ended

Dec. 31, 2017

Trade payables and accrued liabilities [Abstract]

Trade payables and accrued liabilities

10.	Trade payables and accrued liabilities

	For the Years Ended December 31,
in CHF thousands	2017		2016
Trade payables and other payables		1,092		4,035
Accrued research and development costs		5,430		3,265
Accrued payroll expenses		2,420		1,419
Other accrued expenses		457		682
Deferred income		355		521
Total		9,754		9,922

An accrual of CHF 1.1 million and CHF 1.0 million was recognized for performance-related remuneration relating to 2017 and 2016, respectively.

Deferred income

12 Months Ended

Dec. 31, 2017

Deferred income [Abstract]

Deferred income

11.	Deferred income

For the year ended December 31, 2017, the Company has recorded CHF 0.4 million in deferred income in relation to research funding commitments from Biogen. For the year ended December 31, 2016, we received a research contribution from Biogen for research collaboration of $1.5 million (CHF 1.5 million) for the alpha-synuclein and TDP-43 PET imaging programs. As of December 31, 2016, the remaining CHF 521 thousand was recorded as a current liability in deferred income and was recognized as revenue in 2017 as remaining performance obligations were completed.

Long term financing obligation

12 Months Ended

Dec. 31, 2017

Long term financing obligation [Abstract]

Disclosure of Long term financing obligation

12.	Long term financing obligation

On January 4, 2016 and September 13, 2016 for fiscal years 2016 and 2017, respectively, AC Immune obtained separate funding commitment notices from the LuMind Research Down Syndrome Foundation (“LuMind”) totaling $200 thousand in each instance. Per the Research Grant Agreement, the terms stipulate that AC Immune has an obligation to reimburse LuMind for an amount equal to 125% of the then funding commitment made by LuMind to AC Immune. AC Immune has accordingly recorded a long-term financing obligation for the total $400 thousand (CHF 395 thousand) committed and a corresponding interest accrual of $100 thousand (CHF 99 thousand).

Revenues

12 Months Ended

Dec. 31, 2017

Revenues [Abstract]

Revenues

13.

Revenues

	For the Years Ended December 31,
in CHF thousands	2017	2016	2015
Contract revenue	20,255	23,214	39,090
Total	20,255	23,214	39,090

Anti-Abeta antibody in AD - Collaboration agreement of 2006 with Genentech

In November 2006, AC Immune signed an exclusive, worldwide licensing agreement for crenezumab, our humanized monoclonal antibody targeting misfolded Abeta. Genentech commenced Phase 3 clinical studies for crenezumab in the first quarter of 2016. In February 2017, Genentech started a second Phase 3 clinical trial. If crenezumab receives regulatory approval, we will be entitled to receive royalties that are tied to annual sales volumes with different royalty rates applicable in the U.S. and Europe. These percentage rates range from net high single digits to the mid-teens.

Under the agreement with Genentech, we may become eligible to receive payments totaling up to approximately $340 million, excluding royalties. As of December 31, 2017 we have received total payments of $65 million (CHF 70.1 million).

We recognized the Phase 3 July 2015 payment as revenue in our 2015 fiscal year since there was no further performance requirement to be met by the Company. The agreement provides for a second therapeutic product based on the same intellectual property and anti-Abeta antibody compound as well as an anti-Abeta diagnostic product. Genentech may terminate the agreement at any time by providing three months’ notice to us. In such event all costs incurred are still refundable.

Anti-Tau antibody in AD – Collaboration agreement of 2012 with Genentech

In June 2012, we entered into a second partnership with Genentech to commercialize our anti-Tau antibodies for use as immunotherapeutics. The value of this exclusive, worldwide alliance is potentially greater than CHF 400 million and includes upfront and milestone payments. In addition to milestones, we will be eligible to receive royalties on sales at a percentage rate ranging from the mid-single digits to high single digits. The agreement also provides for collaboration on two additional indications built on the same anti-Tau antibody program as well as a potential anti-Tau diagnostic product.

To date, we have received payments totaling CHF 59 million, including a CHF 14 million milestone payment recognized and payment received in the fourth quarter of 2017 associated with the first patient dosing in a Phase 2 clinical trial for Alzheimer’s Disease with an anti-Tau monoclonal body known as RO7105705, a CHF 14 million milestone payment recognized in the second quarter of 2016 and received in July 2016, associated with the recent announcement of the commencement of the Phase 1 clinical study of the lead anti-Tau antibody candidate and a CHF 14 million milestone payment received in 2015 in connection with the ED-GO decision.

Genentech may terminate the agreement at any time by providing three months’ notice to us. In such event all costs incurred are still refundable.

Tau Vaccine in AD – Collaboration agreement of 2014 with Janssen Pharmaceuticals

In December 2014, we entered into a partnership with Janssen Pharmaceuticals, a Johnson & Johnson company, to develop and commercialize therapeutic anti-Tau vaccines for the treatment of AD and potentially other Tauopathies. The partnership includes a worldwide exclusive license and research collaboration. We and Janssen will co-develop the lead therapeutic vaccine, ACI-35, through Phase 1b completion. From Phase 2 and onward, Janssen will assume responsibility for the clinical development, manufacturing and commercialization of ACI-35. ACI-35 is an active therapeutic vaccine stimulating the patient’s immune system to produce a polyclonal antibody response against phosphorylated Tau protein.

The agreement also allows for the collaboration to be expanded to a second indication based on the same anti-Tau vaccine program and intellectual property related to this program.

We received an upfront payment of CHF 25.9 million which we recognized in 2014 and are eligible to receive development, regulatory and commercialization milestone payments for AD and a potential second indication outside of AD. Additionally, we will receive royalties on sales at a percentage rate ranging from the low double digits to mid-teens. The two companies have entered into a three-year joint research collaboration, which was subsequently amended to five years, to further characterize and develop novel vaccine therapies for the treatment of Tauopathies.

The recognition of the upfront payment from Janssen was recorded at the time of receipt as the Company determined that the license granted to Janssen was a separate, non-contingent deliverable under the agreement. The Company determined the license had stand-alone value based on Janssen’s ability to create value from the license without our research and development support services due their extensive experience in vaccine development and production which would allow them to complete the phase 1b clinical trials.

In 2016, we received payments of CHF 1.5 million for pre-payment of research and external research costs. Pursuant to the terms of the collaboration agreement, there is a performance obligation until the end of the year. As a result, we recognized the proceeds from the milestone payment over a 12-month period on a straight-line basis. In May 2016, we received a CHF 4.9 million payment for reaching a clinical milestone in the Phase 1b study. As we met all performance obligations on reaching the milestone, we have recognized related revenue.

In July 2017, AC Immune and Janssen entered into a Second Amendment to the December 2014 License, Development and Commercialization Agreement. The Amendment allows for the alignment of certain payment provisions with the new Development Plan and Research Plan activities. ACI and Janssen will jointly share R&D costs until the completion of the first Phase 2 or first Phase 3 trial begins. Under the terms of the agreement, Janssen may terminate the agreement at any time after completion of the Phase 1b clinical study by providing 90 days’ notice to us.

Tau-PET imaging agent in AD – License and Collaboration agreement of 2014 with Piramal Imaging

In May 2014, AC Immune SA entered into an LCA, our first diagnostic partnership with Piramal Imaging (“Piramal”), a division of Piramal Enterprises, Ltd. The LCA with Piramal is an exclusive, worldwide licensing agreement for the research, development and commercialization of the Company’s Tau protein positron emission tomography (PET) tracers supporting the diagnosis and clinical management of AD and potential Tau-related disorders and includes upfront and sales milestone payments totaling up to EUR 157 million, plus royalties on sales at a percentage rate ranging from mid-single digits to low double digits.

The upfront payment of EUR 500 thousand received from this collaboration was deferred over a period of 12 months which was the joint Research Collaboration period. As such, the residual balance in deferred revenue related to this collaboration at December 31, 2014, was fully recognized until May 2015.

In March 2017, we invoiced Piramal for a CHF 1.1 million milestone related to the initiation of “Part B” of the first-in-man Phase 1 clinical trial for PSP (Progressive Supranuclear Palsy). As we met all performance obligations on reaching the milestone, we have recognized this milestone as revenue in the first quarter of fiscal 2017 and received payment in Q4 2017. We are also entitled to further clinical milestones totaling EUR 6 million should the compound make it through to Phase 3 clinical studies and are further entitled to potential regulatory, commercialization and sales based milestones totaling EUR 150 million.

Piramal may terminate the LCA agreement by providing three months’ notice to the Company.

Alpha-synuclein and TDP-43 PET tracer in AD – Collaboration agreement of 2016 with Biogen

On April 13, 2016, AC Immune entered into a non-exclusive research collaboration agreement with Biogen International GmbH, or Biogen. Under the agreement, we and Biogen have agreed to collaborate in the research and early clinical development of our alpha-synuclein PET Tracer program for Parkinson’s disease and other synucleinopathies, and a second program for the identification, research and development of novel PET ligands against TDP-43, a protein recently linked to neurodegeneration in diseases such as amyotrophic lateral sclerosis. In addition, we have agreed to share the costs of the collaboration, with Biogen primarily funding the majority of research costs, subject to a cap, which includes an upfront technology access fee and funding towards research and development personnel. We will own all intellectual property rights to any invention relating to alpha-synuclein or TDP-43 PET tracers.

In April 2017, we began the second year of our collaboration and have recognized CHF 3.4 million for research contribution and collaboration services. We have also recognized the remaining CHF 0.5 million related to the technology access fee bill in April 2016 which was amortized over a 12-month period.

As of December 31, 2017, CHF 355 thousand is recorded as a current liability in deferred income and is expected to be recognized as revenue in 2018 as remaining performance obligations are completed.

Recombinant protein therapeutic candidate – Collaboration with Essex Bio-Technology Limited

On May 19, 2017, we entered into a Research Project Agreement with Essex Bio-Technology Limited, or Essex, to develop a recombinant protein therapeutic candidate acting on a unique neuroprotective mechanism for treatment of neurological diseases, such as Alzheimer’s disease and frontotemporal dementia. Essex will provide joint research commitment as well as financial support to AC Immune for the pre-IND development of the biological agent.

As part of this agreement, the parties have agreed to an initial two year Research Plan, which intends to develop a basic Fibroblast Growth Factor ("bFGF") as a therapeutic for the treatment of neurodegenerative diseases and to generate novel antibody therapeutics.

Under the terms of the agreement, Essex will provide support to AC Immune until the selection of a collaboration product by the Joint Steering Committee, up to a maximum of CHF 750 thousand per year. The Company recognized CHF 78 thousand for the year ended December 31, 2017.

Continuation of 2015 Grant from the Michael J. Fox Foundation

On September 16, 2017, AC Immune formally signed a one year grant continuation with the Michael J. Fox Foundation for Parkinson’s Disease research. This grant provides funds for the development of Positron Emission Tomography (PET) tracers for the alpha-synuclein protein, to support the early diagnosis and clinical management of Parkinson’s disease. The Company recognized CHF 95 thousand for research services performed for the year ended December 31, 2017.

Expenses by category

12 Months Ended

Dec. 31, 2017

Expenses by category [Abstract]

Expenses by category

14.	Expenses by category

Research and Development

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Operating expenses		23,822		18,767		10,763
Payroll expenses		8,552		6,450		5,879
Share-based compensation		289		557		407
Total research and development expenses		32,663		25,774		17,049

General and Administrative

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Operating expenses		3,857		3,168		1,377
Payroll expenses		4,984		3,969		1,908
Share-based compensation		1,290		759		132
Total general and administrative expenses		10,131		7,896		3,417

Financial Result, net

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Interest income/ (expense)		184			36			55
Foreign currency remeasurement gain/(loss), net		(4,049	)		3,443			1,598
Other finance income/(expense)		(7	)		(119	)		(7	)
Finance result, net		(3,872	)		3,360			1,646

Related-party transactions

12 Months Ended

Dec. 31, 2017

Related-party transactions

15.	Related-party transactions

Key management including the Board of Directors (five individuals excluding the CEO) and the Executive Management (four individuals) compensation was:

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Short-term employee benefits		2,463		2,251		1,776
Post-employment benefits		166		154		124
Share-based compensation		1,267		832		8
Total		3,896		3,237		1,908

In April 2017, Joerg Hornstein was named the Chief Financial Officer and a member of the Executive Management. He replaced the former CFO whose tenure ended in November 2016.

Friedrich von Bohlen and Peter Bollmann joined the Board of Directors of AC Immune in October and December 2015, respectively. Friedrich von Bohlen replaced Christof Hettich who stepped down from the Board in August 2015. Hans-Beat Guertler resigned from the board in December 2015. His position was assumed by Peter Bollmann. In November 2016, Mr. Thomas Graney joined the Board of Directors of AC Immune, replacing Mathias Hothum as his term expired.

Short-term employee benefits comprise of salaries, bonuses, social security and expense allowances.

257,916, 98,500, and 45,000 options were granted in 2017, 2016 and 2015, respectively, to the Executive Management of the Company. No options were granted in 2017, 2016, and 2015, respectively, to the Directors of the Company. In connection with his departure in the fourth quarter of 2016, the former Chief Financial Officer forfeited his initial 2016 grant (included in the aggregate 2016 total above), and in its place was awarded 49,250 options. The fourth quarter 2016 grant date fair value of the replacement award was CHF 674 thousand.

The Company granted 4,023 Restricted Shares as part of a Restricted Share Award to one of our Directors in accordance with our 2016 Stock Option and Incentive Plan in 2017. No such awards were issued in 2016 and 2015.

In the third quarter of fiscal 2017, the Company granted 125,332 Restricted Share Units to certain members of the Board of Directors and Executive Management. No such awards were issued in 2016 and 2015.

Income taxes

12 Months Ended

Dec. 31, 2017

Income taxes [Abstract]

Income taxes

16.	Income taxes

The Company recognized no income tax expense or deferred tax asset or liability positions for the years ended December 31, 2017, 2016, and 2015.

The income tax expense for each year can be reconciled to Income / (loss) before tax as follows:

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Income / (loss) before income tax		(26,411	)		(7,096	)		20,270
Tax expense / (benefit) calculated at the statutory rate of 20.5% (21% for 2016 and 22% for 2015)		(5,420	)		(1,504	)		4,566
Effect of Swiss Tax Holidays		-			-			-
Permanent differences		40			(166	)		-
Effect of unrecognized carry forward tax loss		-			-			(4,566	)
Effect of unused tax losses and tax offsets not recognized as deferred tax assets		5,380			1,670			-
Effective income tax rate benefit / (expense)		-			-			-

The tax rate used for the 2017 reconciliations above is the corporate tax rate of 20.5% (21%: 2016 and 22% : 2015) payable by corporate entities in the Canton of Vaud, Switzerland on taxable profits under tax law in that jurisdiction.

In 2015, AC Immune was able to apply tax loss carryforwards to reduce its effective tax rate to zero.

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Unrecognized deductible temporary differences, unused tax losses and unused tax credits
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized are attributable to the following:
- Tax losses		62,575		36,707		29,079
- Deductible temporary differences related to the retirement benefit plan		4,926		3,798		2,787

Total		67,501		40,505		31,866

Deductible temporary differences related to the retirement benefit plan do not expire. Tax losses expiry dates are shown in the table below:

in CHF thousands	2017		2016		2015
Tax losses split by expiry date
December 31, 2017		-		-		-
December 31, 2018		2,175		2,175		2,175
December 31, 2019		16,566		16,566		16,566
December 31, 2020		10,338		10,338		10,388
December 31, 2021		-		-		-
December 31, 2022		-		-		-
December 31, 2023		7,628		7,628		-
December 31, 2024		25,868		-		-
Total		62,575		36,707		29,079

The tax losses available for future offset against taxable profits have increased by CHF 25.9 million from 2016, representing the amount of tax losses that are additionally available as an offset, subject to expiration as disclosed in the table above, against future taxable income.

Consistent with prior years, the Company has not recorded any deferred tax assets in relation to the past tax losses available for offset against future profits as the recognition criteria have not been met at the balance sheet date.

Retirement benefit plan

12 Months Ended

Dec. 31, 2017

Retirement benefit plan [Abstract]

Retirement benefit plan

17.	Retirement benefit plan

The Company participates in a collective foundation covering all of its employees including its executive officers. In addition to retirement benefits, the plan provides death or long-term disability benefits.

Contributions paid to the plan are computed as a percentage of salary, adjusted for the age of the employee and shared approximately 47% and 53% by employee and employer, respectively.

This plan is governed by the Swiss Law on Occupational Retirement, Survivors and Disability Pension Plans (BVG), which requires contributions to be made to a separately administered fund. The fund has the legal form of a foundation and it is governed by the board of trustees, which consists of an equal number of employer’s and employee’s representatives. The board of trustees is responsible for the administration of the plan assets and for the definition of the investment strategy.

The collective foundation is governed by a foundation board. The board is made up of an equal number of employee and employer representatives of the different affiliated companies. The Company has no direct influence on the investment strategy of the foundation board.

The assets are invested by the pension plan, to which many companies contribute, in a diversified portfolio that respects the requirements of the Swiss BVG. Therefore disaggregation of the pension assets and presentation of plan assets in classes that distinguish the nature and risks of those assets is not possible. Under the Plan, both the Company and the employee share the costs equally. The structure of the plan and the legal provisions of the BVG mean that the employer is exposed to actuarial risks. The main risks are investment risk, interest risk, disability risk and the life expectancy of pensioners. Through our affiliation with the pension plan, the Company has minimized these risks, since they are shared between a much greater number of participants. On leaving the Company, a departing employee’s retirement savings are transferred to the pension institution of the new employer or to a vested benefits institution. This transfer mechanism may result in pension payments varying considerably from year to year.

The pension plan is exposed to Swiss inflation, interest rate risks and changes in the life expectancy for pensioners.

For accounting purposes under IFRS, the plan is treated as a defined benefit plan. Liabilities are calculated annually by an independent actuary. Plan assets have been estimated at their fair market value and liabilities have been calculated according to the “Projected Unit Credit” method.

The following table sets forth the status of the defined benefit pension plan and the amount that should be recognized in the balance sheet:

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Defined benefit obligation	(14,278	)	(11,596	)		(9,439	)
Fair value of plan assets	9,352		7,798			6,652
Total liability	(4,926	)	(3,798	)		(2,787	)

The following amounts have been recorded as net pension cost in the statement of income:

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Service cost		912			742			641
Interest cost		81			75			101
Interest income		(55	)		(56	)		(76	)
Impact of plan amendment		-			-			(584	)
Net pension cost		938			761			82

The changes in defined benefit obligation, fair value of plan assets and unrecognized (gains) / losses are as follows:

A.	Change in defined benefit obligation

in CHF thousands	2017			2016			2015
Defined benefit obligation as of January 1		(11,596	)		(9,439	)		(8,091	)
Service cost		(912	)		(742	)		(641	)
Interest cost		(81	)		(75	)		(101	)
Change in demographic assumptions		—			(389	)		—
Change in financial assumptions		—			(26	)		(591	)
Other actuarial gains / (losses)		(735	)		(378	)		(176	)
Plan amendment		—			—			584
Benefit payments		(426	)		(111	)		(48	)
Employees’ contributions		(528	)		(436	)		(375	)
Defined benefit obligation as of December 31		(14,278	)		(11,596	)		(9,439	)

B.	Change in fair value of plan assets

in CHF thousands	2017			2016		2015
Fair value of plan assets as of January 1		7,798			6,652		5,681
Interest income		55			56		76
Employees’ contributions		528			436		375
Employer’s contributions		590			511		441
Benefits payments		426			111		48
Plan assets gains/(losses)		(45	)		32		31
Fair value of plan assets as of December 31		9,352			7,798		6,652

Employer’s contribution to the pension plan for the financial year 2018 are estimated to be CHF 630 thousand.

C.	Change in net defined benefit liability

in CHF thousands	2017			2016			2015
Net defined benefit liabilities as of January 1		3,798			2,787			2,410
Net pension cost through statement of income		938			761			82
Re-measurement through other comprehensive income		780			761			736
Employer’s contribution		(590	)		(511	)		(441	)
Net defined benefit liabilities as of December 31		4,926			3,798			2,787

The fair value of the plan assets is the cash surrender value of the insurance with AXA. The investment strategy defined by the board of trustees follows a conservative profile.

The plan assets are primarily held within instruments with quoted market prices in an active market, with the exception of real estate and mortgages.

The weighted average duration of the defined benefit obligation is 20.5 years as of December 31, 2017.

The actuarial assumptions used for the calculation of the pension cost and the defined benefit obligation of the defined benefit pension plan for the year 2017, 2016 and 2015 are as follows:

	For the Years Ended December 31,
	2017			2016			2015
Discount rate		0.70	%		0.70	%		1.25	%
Rate of future increase in compensations		1.50	%		1.50	%		1.50	%
Rate of future increase in current pensions		0.50	%		0.50	%		0.50	%
Mortality and disability rates	BVG 2015G			BVG 2015G			BVG 2010G

In defining the benefits, the minimum requirements of the Swiss Law on Occupational Retirement, Survivors and Disability Pension Plans (BVG) and its implementing provisions must be observed. The BVG defines the minimum pensionable salary and the minimum retirement credits.

A quantitative sensitivity analysis for significant assumption as of December 31, 2017 is as shown below:

		Discount rate				Future salary increase					Future pension cost
Assumptions		+0.5% increase	-0.5% decrease			+0.5% increase			-0.5% decrease		+0.5% increase			-0.5% decrease
	in CHF thousands
Defined benefit obligation		12,707		15,849			14,449			14,121		14,989			13,564
Impact on the net defined benefit obligation		1,571		(1,571	)		(171	)		157		(711	)		714

The sensitivity analyses above is subject to limitations and has been determined based on a method that extrapolates the impact on net defined benefit obligation as a result of reasonable changes in key assumptions occurring at the end of the reporting period.

Share-based compensation

12 Months Ended

Dec. 31, 2017

Share-based compensation [Abstract]

Share-based compensation

18.	Share-based compensation

Through the year ended December 31, 2017, the Company has issued equity-based instruments under four different plans that existed in 2017 as outlined in the table below.

The Company’s 2016 Share Option and Incentive Plan (“Plan”) was approved by the shareholders at the Ordinary Shareholder’s meeting in November 2016. The 2016 Plan authorizes the grant of incentive and non-qualified share options, share appreciation rights, restricted share awards, restricted share units, unrestricted share awards, performance share awards, performance-based awards to covered employees and dividend equivalent rights.

The following table summarizes equity settled share option grants since inception under each plan:

PLAN	Number of options awarded (since inception)	Vesting conditions	Contractual life of options
Share option plan A	362,750	At grant	15.5 years
Share option plan B	819,000	At grant	10.5 years
Share option plan C1	6,775,250	4 years’ service from grant date	10 years
2016 Share Option and Incentive Plan:
Executives and Directors	257,916	4 years’ service from the date of grant, quarterly	10 years
Employees	18,850	4 years’ service from the date of grant, annually	10 years

The number and weighted average exercise prices (in CHF) of options under the share option programs for Plans A, B, C1 and 2016 are as follows:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Term (Years)
Outstanding at January 1, 2015		4,006,500			0.21668		4.5
Forfeited during the year		(23,250	)		0.14548		-
Cancelled during the year		(15,250	)		0.14548		-
Exercised during the year		(594,250	)		0.14548		-
Granted during the year		223,250			0.14548		-
Outstanding at December 31, 2015		3,597,000			0.14548		3.6
Exercisable at December 31, 2015		3,032,500			0.14548		3.4
Outstanding at January 1, 2016		3,597,000			0.14548		3.6
Forfeited during the year		(106,000	)		0.14548		-
Cancelled during the year		(19,250	)		0.14548		-
Exercised during the year		(2,069,100	)		0.14548		-
Granted during the year		285,250			0.14548		-
Outstanding at December 31, 2016		1,687,900			0.14548		5.6
Exercisable at December 31, 2016		1,284,525			0.14548		6.5
Outstanding at January 1, 2017		1,687,900			0.14548		5.6
Forfeited during the year		(1,750	)		0.14548		-
Cancelled during the year		(31,250	)		0.14548		-
Exercised during the year		(571,775	)		0.14548		-
Granted during the year		276,766			9.70		-
Outstanding at December 31, 2017		1,359,891			2.09		5.8
Exercisable at December 31, 2017		900,474			0.39		4.3

The weighted average exercise price for options granted in 2017, 2016 and 2015 is CHF 9.70, CHF .14548 and CHF .14548, respectively. The range of exercise prices for outstanding options was CHF 0.14548 to CHF 12.00 as of December 31, 2017 and 0.14548 as of December 31, 2016 and 2015.

The weighted average fair values of the options granted in 2017, 2016 and 2015 are CHF 7.29, CHF 5.85, and CHF 1.77, respectively. These fair values of options granted have been determined using the Black-Scholes option pricing model and an exercise price ranging from CHF 9.53 to CHF 12.00 in 2017 (2016 and 2015: CHF 0.14548), a weighted average share price of CHF 8.77 (2016: CHF 5.96 and 2015: CHF 1.91), a risk-free interest rate of 0% (2016 and 2015: 0%) and a volatility of 80% (2016: 80% and 2015: 50%) with an expected duration of 6 years (2016 and 2015: 6 years). All options expire 10 years from the grant date unless otherwise noted.

Prior to the IPO, the exercise price was set by the Board of Directors. The volatility is based on the historical trend of an appropriate sample of companies operating in the biotech and pharmaceutical industry. The risk-free interest rate is based on the CHF swap rate for the expected life of the option. The weighted average share price of common share options exercised in 2017 is CHF 10.53 (2016: CHF 6.22 and 2015: CHF 1.91).

The expense charged against the income statement for the financial year 2017 amounts to CHF 1,579 thousand (2016: CHF 1,317 thousand and 2015: 540 thousand). The expense is revised by the Company based on the number of instruments that are expected to become exercisable. The 2016 expense also reflects a share based option award that was modified in 2016 to amend the option grant’s contractual life and the issuance of a replacement award. An incremental fair value of CHF 238 thousand was immediately recognized in 2016 as a result of the modification of the share options contractual life. Additionally, in connection with former CFO departure in the fourth quarter of 2016, the former Chief Financial Officer forfeited his initial 2016 grant (included in the aggregate 2016 total of 98,500), and in its place was awarded 49,250 options, which has been accounted for as a new award granted on the date of forfeiture of the original award. The fourth quarter 2016 grant date fair value of the replacement award was CHF 674 thousand. The fair value of the modified award was measured using the Black-Scholes option pricing model with similar assumptions to the 2016 option, except for a currently quoted common share price as of the date of the modification.

The following table summarizes non-vested share awards (restricted share and restricted share units) during the year ended December 31, 2017 (no such awards were granted in 2016 and 2015, respectively):

Grantee Type	Number of non-vested share awards granted	Vesting conditions	Contractual life of non-vested share awards
Restricted Share Units
Directors	29,375	1 year service from date of grant, annually	10 years
Executives	95,957	4 years’ service from the date of grant, quarterly	10 years
Restricted Share Awards	4,023	2.75 years’ service from date of grant, quarterly	10 years

	Number of non-vested shares		Weighted average grant date fair value
Non-vested at January 1, 2017		-		-
Forfeited during the year		-		-
Cancelled during the year		-		-
Exercised during the year		-		-
Granted during the year		129,355		9.62
Non-vested at December 31, 2017		122,014		9.59
Vested at December 31, 2017		7,341		10.06

The weighted average grant date fair value of the restricted share awards granted (restricted shares and restricted share units) in 2017 was CHF 9.62. No RSAs or RSUs were granted in 2016 and 2015. The weighted average grant date fair values of the non-vested share awards granted (restricted shares and restricted share units) in 2017, 2016 and 2015 are CHF 9.59, 0 and 0, respectively. These fair values of non-vested share awards granted have been determined using a reasonable estimate of market value of the common stock on the date of the award.

Commitments and contingencies

12 Months Ended

Dec. 31, 2017

Commitments and contingencies [Abstract]

Commitments and contingencies

19.	Commitments and contingencies

	For the Years Ended December 31,
in CHF thousands	2017		2016
Within one year		9,686		9,175
Between one and three years		2,546		1,624
Between three and five years		140		-
More than five years		-		-
Total		12,372		10,799

The Company has research contracts with several external service providers. As of December 31, 2017 external research projects for CHF 9.4 million were committed for 2018. Rental contract for laboratory and offices space at the EPFL Innovation Park in Ecublens/Lausanne can be cancelled within a 6 month notice period. Lease expense in 2017 was CHF 0.5 million. As of December 31, 2017, rental contracts for CHF 0.2 million were committed for 2018.

The Company has a contractual obligation that requires the payment of royalties to a third party, which is associated with the achievement of program milestones. As of December 31, 2017, the Company’s contractual obligation associated with this agreement was CHF 0.4 million.

Earnings per share

12 Months Ended

Dec. 31, 2017

Earnings per share [Abstract]

Earnings per share

20.	Earnings per share

	For the Years Ended December 31,
in CHF thousands except for share and per share data	2017			2016			2015
Net income / (loss) attributable to owners of the Company		(26,411	)		(7,096	)		20,270
Earnings per share (EPS):
Basic, income / (loss) for the period attributable to equity holders		(0.46	)		(0.14	)		0.47
Diluted, income / (loss) for the period attributable to equity holders		(0.46	)		(0.14	)		0.44
Weighted-average number of shares used to compute EPS basic		57,084,295			50,096,859			43,412,250
Weighted-average number of shares used to compute EPS fully diluted		57,084,295			50,096,859			46,043,198

For the years ended December 31, 2017, 2016 and 2015 basic and diluted earnings per share is based on the weighted average number of shares issued and outstanding. Weighted-average dilutive shares outstanding excludes antidilutive shares to be issued that totaled 1,463,056 and 1,687,900 from the computation of diluted income (loss) per common share for the years-ended December 31, 2017 and 2016, respectively. The weighted average number of equity awards outstanding for the years ended December 31, 2017 and 2016 was 1,582,612 and 2,784,245, respectively.

Financial instruments and risk management

12 Months Ended

Dec. 31, 2017

Financial instruments and risk management [Abstract]

Financial instruments and risk management

21.	Financial instruments and risk management

The Company’s activities expose it to the following financial risks: market risk (currency risk), credit risk and liquidity risk. The Company’s overall risk management program focuses on the unpredictability of financial markets and seeks to minimize potential adverse effects on the Company’s financial performance.

The following table shows the carrying amounts of financial assets and financial liabilities:

	For the Years Ended December 31,
in CHF thousands	2017		2016
Financial assets
Other current receivables		918		517
Cash and cash equivalents		124,377		152,210
Total financial assets		125,295		152,727

Financial liabilities
Long-term financing obligation		395		-
Trade and other payables		1,092		4,035
Accrued expenses		8,307		5,366
Total financial liabilities		9,794		9,401

Foreign exchange risk

The Company is exposed to foreign exchange risk arising from currency exposures, primarily with respect to the EUR, USD and to a lesser extent to GBP, DKK and SEK. The currency exposure is not hedged. However, the Company has a policy of matching its cash holdings to the currency structure of its expenses, which means that the Company holds predominately CHF, EUR and USD (see also Note 8). In the Company’s income statements for the years ended December 31, 2017, 2016 and 2015 a loss of 4.2 million and a gain of CHF 3.4 million and CHF 1.6 million, respectively, is recognized in the financial statement line item “Finance Income/(expense), net.”

Credit risk

The majority of the cash and cash equivalents is held within one bank. However, the credit risk on liquid funds is limited because the counterparty is a bank with a high credit-rating assigned by international credit-rating agencies. The maximum amount of credit risk is the carrying amount of the financial assets. Trade and other receivables are fully performing, not past due and not impaired (see Note 6).

Liquidity risk

Inherent in the Company’s business are various risks and uncertainties, including its limited operating history and the high uncertainty that new therapeutic concepts will succeed. AC Immune’s success may depend in part upon its ability to (i) establish and maintain a strong patent position and protection, (ii) enter into collaborations with partners in the biotech and pharmaceutical industry, (iii) acquire and keep key personnel employed, and (iv) acquire additional capital to support its operations.

The Company’s approach of managing liquidity is to ensure sufficient cash to meet its liabilities when due. Therefore, management closely monitors the cash position on rolling forecasts based on expected cash flow to enable the Company to finance its operations for at least 18 months.

Based on the current cash position, the Company is well financed through the second quarter of 2019.

Foreign currency

The Company undertakes certain transactions denominated in foreign currencies. Hence, exposure to exchange rate fluctuations arises. Exchange rate exposures are managed by matching its cash holdings to the currency structure of its expenses.

As of December 31, 2017, if the CHF had strengthened/weakened by 10% against the EUR and the USD with all other variables held constant, the net loss for the period would have been lower/higher by CHF 2.1 million (2016: CHF 10.9 million), mainly as a result of foreign exchange gains/losses on predominantly EUR/USD denominated cash and cash equivalents.

Interest rates

The Company is not materially exposed to any interest rates fluctuations.

Capital risk management

12 Months Ended

Dec. 31, 2017

Capital risk management [Abstract]

Capital risk management

22.	Capital risk management

The Company’s objectives when managing capital are to safeguard the Company’s ability to continue as a going concern and to preserve the capital on the required statutory level in order to succeed in developing a cure against AD.

Post balance sheet events

12 Months Ended

Dec. 31, 2017

Post balance sheet events [Abstract]

Post balance sheet events

23.	Post balance sheet events

On February 2, 2018, we entered into an additional lease with the EPFL Innovation Park to expand our premises by more than 4,300 square feet effective March 1, 2018. As part of this expansion, the Company agreed to purchase CHF 750 thousand of the previous tenant’s lab equipment.

Summary of significant accounting policies (Policies)

12 Months Ended

Dec. 31, 2017

Summary of significant accounting policies [Abstract]

Current vs. non-current classification

Foreign currency transactions

Revenue recognition

License of intellectual property

For collaboration agreements, in addition to receiving upfront payments, the Company is also entitled to milestone and other contingent payments upon achieving pre-defined objectives.

Milestone payments

Research and development services

Research and Development Services

Research and development expenditure

Given the stage of development of the Company’s products, all research expenditure is recognized as expense when incurred. Research and development expenditures include:

fees and costs related to regulatory filings and activities;

costs associated with pre-clinical and clinical activities; and

employee-related expenses, including salaries and bonuses, benefits, travel and stock-based compensation expense

Property, plant and equipment

IT equipment	3 years
Laboratory equipment	5 years
Leasehold improvements / furniture	5 years

Gains and losses on disposals are determined by comparing the disposal proceeds with the carrying amount and are included in the Statements of Income / (Loss).

Financial assets and liabilities

Receivables

Cash and cash equivalents

Trade payables

Trade payables are recognized initially at fair value, which represents cost incurred.

Long-term financing obligation

The Company’s long-term financing obligation is measured as of the period end date based on the repayment terms when originated.

Share capital and Initial Public Offering

Preferred Shares

Initial Public Offering (IPO)

Employee benefits

Post-employment benefits

Share-based compensation

The proceeds received net of any directly attributable transaction costs are credited to share capital (nominal value) and share premium when the options are exercised.

Provisions

Taxation

Earnings per share

Critical judgments and accounting estimates

Income taxes

Preferred shares

Segment reporting

The Company has one segment. The Company currently focuses all of its resources on discovering and developing therapeutic and diagnostic products targeting misfolded proteins.

Accounting pronouncements - not yet adopted

Accounting pronouncements – not yet adopted

Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary of significant accounting policies [Abstract]

Estimated useful life

Depreciation is calculated using a straight-line method to write off the cost of each asset to its residual value over its estimated useful life as follows:

IT equipment	3 years
Laboratory equipment	5 years
Leasehold improvements / furniture	5 years

Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, plant and equipment [Abstract]

Property, plant and equipment

	As of December 31, 2017
	Furniture			Computers/IT			Lab Equipment			Leasehold Improvements			Total
Acquisition Cost:
Balance at the end of the previous year		81			298			2,792			103			3,274
Acquisitions		4			271			1,369			169			1,813
Balance at end		85			569			4,161			272			5,087

Accumulated depreciation:
Balance at the end of the previous year		(45	)		(172	)		(1,858	)		(79	)		(2,154	)
Depreciation expense		(14	)		(87	)		(453	)		(26	)		(580	)
Balance at end		(59	)		(259	)		(2,311	)		(105	)		(2,734	)

Carrying Amount:
December 31, 2016		36			126			934			24			1,120
December 31, 2017		26			310			1,850			167			2,353

	As of December 31, 2016
	Furniture			Computers/IT			Lab Equipment			Leasehold Improvements			Total
Acquisition Cost:
Balance at the end of the previous year		43			172			2,058			103			2,376
Acquisitions		38			126			734			-			898
Balance at end		81			298			2,792			103			3,274

Accumulated depreciation:
Balance at the end of the previous year		(36	)		(138	)		(1,629	)		(73	)		(1,876	)
Depreciation expense		(9	)		(34	)		(229	)		(6	)		(278	)
Balance at end		(45	)		(172	)		(1,858	)		(79	)		(2,154	)

Carrying Amount:
December 31, 2015		7			34			429			30			500
December 31, 2016		36			126			934			24			1,120

Prepaid expenses and accrued income (Tables)

12 Months Ended

Dec. 31, 2017

Prepaid expenses and accrued income [Abstract]

Prepaid expenses and accrued income

	For the Years Ended December 31,
in CHF thousands	2017	2016
Prepaid expenses	1,440	1,278
Accrued income	2,799	889
Total	4,239	2,167

Other current receivables (Tables)

12 Months Ended

Dec. 31, 2017

Other current receivables [Abstract]

Other current receivables

	For the Years Ended December 31,
in CHF thousands	2017		2016
Other receivables		691		182
Swiss VAT		112		320
Withholding tax		115		15
Total		918		517

Cash and cash equivalents (Tables)

12 Months Ended

Dec. 31, 2017

Cash and cash equivalents [Abstract]

Cash and cash equivalents

	For the Years Ended December 31,
in CHF thousands	2017		2016
Cash		124,377		152,210
Total		124,377		152,210

By Currency
CHF		103,272		41,322
EUR		3,658		6,727
USD		17,447		104,161
Total		124,377		152,210

Share capital (Tables)

12 Months Ended

Dec. 31, 2017

Share capital [Abstract]

Summary of capital structure

The table below summarizes the Company’s capital structure:

	For the Years Ended December 31,
	2017		2016
	Number	CHF	Number	CHF
Common shares with a nominal value of CHF 0.02 each	57,355,188	1,147,104	56,773,392	1,135,468
Total	57,355,188	1,147,104	56,773,392	1,135,468

Trade payables and accrued liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Trade payables and accrued liabilities [Abstract]

Trade payables and accrued liabilities

	For the Years Ended December 31,
in CHF thousands	2017		2016
Trade payables and other payables		1,092		4,035
Accrued research and development costs		5,430		3,265
Accrued payroll expenses		2,420		1,419
Other accrued expenses		457		682
Deferred income		355		521
Total		9,754		9,922

Revenues (Tables)

12 Months Ended

Dec. 31, 2017

Revenues [Abstract]

Revenues

	For the Years Ended December 31,
in CHF thousands	2017	2016	2015
Contract revenue	20,255	23,214	39,090
Total	20,255	23,214	39,090

Expenses by category (Tables)

12 Months Ended

Dec. 31, 2017

Expenses by category [Abstract]

Research and Development

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Operating expenses		23,822		18,767		10,763
Payroll expenses		8,552		6,450		5,879
Share-based compensation		289		557		407
Total research and development expenses		32,663		25,774		17,049

General and Administrative

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Operating expenses		3,857		3,168		1,377
Payroll expenses		4,984		3,969		1,908
Share-based compensation		1,290		759		132
Total general and administrative expenses		10,131		7,896		3,417

Financial Result, net

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Interest income/ (expense)		184			36			55
Foreign currency remeasurement gain/(loss), net		(4,049	)		3,443			1,598
Other finance income/(expense)		(7	)		(119	)		(7	)
Finance result, net		(3,872	)		3,360			1,646

Related-party transactions (Tables)

12 Months Ended

Dec. 31, 2017

Key management compensation

Key management including the Board of Directors (five individuals excluding the CEO) and the Executive Management (four individuals) compensation was:

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Short-term employee benefits		2,463		2,251		1,776
Post-employment benefits		166		154		124
Share-based compensation		1,267		832		8
Total		3,896		3,237		1,908

Income taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income taxes [Abstract]

Income tax expense reconciled to Income / (loss)

The income tax expense for each year can be reconciled to Income / (loss) before tax as follows:

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Income / (loss) before income tax		(26,411	)		(7,096	)		20,270
Tax expense / (benefit) calculated at the statutory rate of 20.5% (21% for 2016 and 22% for 2015)		(5,420	)		(1,504	)		4,566
Effect of Swiss Tax Holidays		-			-			-
Permanent differences		40			(166	)		-
Effect of unrecognized carry forward tax loss		-			-			(4,566	)
Effect of unused tax losses and tax offsets not recognized as deferred tax assets		5,380			1,670			-
Effective income tax rate benefit / (expense)		-			-			-

Unrecognized deductible temporary differences, unused tax losses and unused tax credits

In 2015, AC Immune was able to apply tax loss carryforwards to reduce its effective tax rate to zero.

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Unrecognized deductible temporary differences, unused tax losses and unused tax credits
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized are attributable to the following:
- Tax losses		62,575		36,707		29,079
- Deductible temporary differences related to the retirement benefit plan		4,926		3,798		2,787

Total		67,501		40,505		31,866

Tax losses expiry dates

Deductible temporary differences related to the retirement benefit plan do not expire. Tax losses expiry dates are shown in the table below:

in CHF thousands	2017		2016		2015
Tax losses split by expiry date
December 31, 2017		-		-		-
December 31, 2018		2,175		2,175		2,175
December 31, 2019		16,566		16,566		16,566
December 31, 2020		10,338		10,338		10,388
December 31, 2021		-		-		-
December 31, 2022		-		-		-
December 31, 2023		7,628		7,628		-
December 31, 2024		25,868		-		-
Total		62,575		36,707		29,079

Retirement benefit plan (Tables)

12 Months Ended

Dec. 31, 2017

Retirement benefit plan [Abstract]

Defined benefit pension plan amounts recognized in the balance sheet and statement of income

The following table sets forth the status of the defined benefit pension plan and the amount that should be recognized in the balance sheet:

	For the Years Ended December 31,
in CHF thousands	2017		2016		2015
Defined benefit obligation	(14,278	)	(11,596	)		(9,439	)
Fair value of plan assets	9,352		7,798			6,652
Total liability	(4,926	)	(3,798	)		(2,787	)

The following amounts have been recorded as net pension cost in the statement of income:

	For the Years Ended December 31,
in CHF thousands	2017			2016			2015
Service cost		912			742			641
Interest cost		81			75			101
Interest income		(55	)		(56	)		(76	)
Impact of plan amendment		-			-			(584	)
Net pension cost		938			761			82

Changes in defined benefit obligation, fair value of plan assets and unrecognized (gains) / losses

The changes in defined benefit obligation, fair value of plan assets and unrecognized (gains) / losses are as follows:

A.	Change in defined benefit obligation

in CHF thousands	2017			2016			2015
Defined benefit obligation as of January 1		(11,596	)		(9,439	)		(8,091	)
Service cost		(912	)		(742	)		(641	)
Interest cost		(81	)		(75	)		(101	)
Change in demographic assumptions		—			(389	)		—
Change in financial assumptions		—			(26	)		(591	)
Other actuarial gains / (losses)		(735	)		(378	)		(176	)
Plan amendment		—			—			584
Benefit payments		(426	)		(111	)		(48	)
Employees’ contributions		(528	)		(436	)		(375	)
Defined benefit obligation as of December 31		(14,278	)		(11,596	)		(9,439	)

B.	Change in fair value of plan assets

in CHF thousands	2017			2016		2015
Fair value of plan assets as of January 1		7,798			6,652		5,681
Interest income		55			56		76
Employees’ contributions		528			436		375
Employer’s contributions		590			511		441
Benefits payments		426			111		48
Plan assets gains/(losses)		(45	)		32		31
Fair value of plan assets as of December 31		9,352			7,798		6,652

Employer’s contribution to the pension plan for the financial year 2018 are estimated to be CHF 630 thousand.

C.	Change in net defined benefit liability

in CHF thousands	2017			2016			2015
Net defined benefit liabilities as of January 1		3,798			2,787			2,410
Net pension cost through statement of income		938			761			82
Re-measurement through other comprehensive income		780			761			736
Employer’s contribution		(590	)		(511	)		(441	)
Net defined benefit liabilities as of December 31		4,926			3,798			2,787

Actuarial assumptions and sensitivity analysis

The actuarial assumptions used for the calculation of the pension cost and the defined benefit obligation of the defined benefit pension plan for the year 2017, 2016 and 2015 are as follows:

	For the Years Ended December 31,
	2017			2016			2015
Discount rate		0.70	%		0.70	%		1.25	%
Rate of future increase in compensations		1.50	%		1.50	%		1.50	%
Rate of future increase in current pensions		0.50	%		0.50	%		0.50	%
Mortality and disability rates	BVG 2015G			BVG 2015G			BVG 2010G

A quantitative sensitivity analysis for significant assumption as of December 31, 2017 is as shown below:

		Discount rate				Future salary increase					Future pension cost
Assumptions		+0.5% increase	-0.5% decrease			+0.5% increase			-0.5% decrease		+0.5% increase			-0.5% decrease
	in CHF thousands
Defined benefit obligation		12,707		15,849			14,449			14,121		14,989			13,564
Impact on the net defined benefit obligation		1,571		(1,571	)		(171	)		157		(711	)		714

Share-based compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share-based compensation [Abstract]

Share-based compensation plans outstanding

The following table summarizes equity settled share option grants since inception under each plan:

PLAN	Number of options awarded (since inception)	Vesting conditions	Contractual life of options
Share option plan A	362,750	At grant	15.5 years
Share option plan B	819,000	At grant	10.5 years
Share option plan C1	6,775,250	4 years’ service from grant date	10 years
2016 Share Option and Incentive Plan:
Executives and Directors	257,916	4 years’ service from the date of grant, quarterly	10 years
Employees	18,850	4 years’ service from the date of grant, annually	10 years

Number and weighted average exercise prices of options for Plans A, B, and C1

The number and weighted average exercise prices (in CHF) of options under the share option programs for Plans A, B, C1 and 2016 are as follows:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Term (Years)
Outstanding at January 1, 2015		4,006,500			0.21668		4.5
Forfeited during the year		(23,250	)		0.14548		-
Cancelled during the year		(15,250	)		0.14548		-
Exercised during the year		(594,250	)		0.14548		-
Granted during the year		223,250			0.14548		-
Outstanding at December 31, 2015		3,597,000			0.14548		3.6
Exercisable at December 31, 2015		3,032,500			0.14548		3.4
Outstanding at January 1, 2016		3,597,000			0.14548		3.6
Forfeited during the year		(106,000	)		0.14548		-
Cancelled during the year		(19,250	)		0.14548		-
Exercised during the year		(2,069,100	)		0.14548		-
Granted during the year		285,250			0.14548		-
Outstanding at December 31, 2016		1,687,900			0.14548		5.6
Exercisable at December 31, 2016		1,284,525			0.14548		6.5
Outstanding at January 1, 2017		1,687,900			0.14548		5.6
Forfeited during the year		(1,750	)		0.14548		-
Cancelled during the year		(31,250	)		0.14548		-
Exercised during the year		(571,775	)		0.14548		-
Granted during the year		276,766			9.70		-
Outstanding at December 31, 2017		1,359,891			2.09		5.8
Exercisable at December 31, 2017		900,474			0.39		4.3

Summary of non-vested share awards (restricted share and restricted share units)

Grantee Type	Number of non-vested share awards granted	Vesting conditions	Contractual life of non-vested share awards
Restricted Share Units
Directors	29,375	1 year service from date of grant, annually	10 years
Executives	95,957	4 years’ service from the date of grant, quarterly	10 years
Restricted Share Awards	4,023	2.75 years’ service from date of grant, quarterly	10 years

	Number of non-vested shares		Weighted average grant date fair value
Non-vested at January 1, 2017		-		-
Forfeited during the year		-		-
Cancelled during the year		-		-
Exercised during the year		-		-
Granted during the year		129,355		9.62
Non-vested at December 31, 2017		122,014		9.59
Vested at December 31, 2017		7,341		10.06

Commitments and contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and contingencies [Abstract]

Maturity of commitments and contingencies

	For the Years Ended December 31,
in CHF thousands	2017		2016
Within one year		9,686		9,175
Between one and three years		2,546		1,624
Between three and five years		140		-
More than five years		-		-
Total		12,372		10,799

Earnings per share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings per share [Abstract]

Earnings per share

	For the Years Ended December 31,
in CHF thousands except for share and per share data	2017			2016			2015
Net income / (loss) attributable to owners of the Company		(26,411	)		(7,096	)		20,270
Earnings per share (EPS):
Basic, income / (loss) for the period attributable to equity holders		(0.46	)		(0.14	)		0.47
Diluted, income / (loss) for the period attributable to equity holders		(0.46	)		(0.14	)		0.44
Weighted-average number of shares used to compute EPS basic		57,084,295			50,096,859			43,412,250
Weighted-average number of shares used to compute EPS fully diluted		57,084,295			50,096,859			46,043,198

Financial instruments and risk management (Tables)

12 Months Ended

Dec. 31, 2017

Financial instruments and risk management [Abstract]

Carrying amounts of financial assets and financial liabilities

The following table shows the carrying amounts of financial assets and financial liabilities:

	For the Years Ended December 31,
in CHF thousands	2017		2016
Financial assets
Other current receivables		918		517
Cash and cash equivalents		124,377		152,210
Total financial assets		125,295		152,727

Financial liabilities
Long-term financing obligation		395		-
Trade and other payables		1,092		4,035
Accrued expenses		8,307		5,366
Total financial liabilities		9,794		9,401

General information (Details)	Dec. 31, 2017 Platform
General information [Abstract]
Number of proprietary technology platforms	2

Basis of preparation (Details) SFr in Thousands, $ in Millions			1 Months Ended		12 Months Ended
	Sep. 22, 2016 CHF (SFr)	Sep. 22, 2016 USD ($)	Apr. 30, 2016 CHF (SFr)	Apr. 30, 2016 USD ($)	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2015 CHF (SFr)	Dec. 31, 2014 CHF (SFr)
Going concern [Abstract]
Company's cash position					SFr 124,377	SFr 152,210	SFr 76,522	SFr 3,306
Private placement extension financing					0	13,206	SFr 29,499
Genentech [Member]
Going concern [Abstract]
Receipt of clinical milestone payment					SFr 14,000	14,000
Janssen [Member]
Going concern [Abstract]
Receipt of clinical milestone payment						SFr 4,900
Initial Public Offering [Member]
Going concern [Abstract]
Gross proceeds received	SFr 74,500	$ 75.9
Series E [Member]
Going concern [Abstract]
Private placement extension financing			SFr 13,200	$ 13.5

Summary of significant accounting policies, Property, plant and equipment (Details)	12 Months Ended
	Dec. 31, 2017
IT Equipment [Member]
Residual value over its estimated useful life [Abstract]
Useful lives or depreciation rates, property, plant and equipment	3 years
Laboratory Equipment [Member]
Residual value over its estimated useful life [Abstract]
Useful lives or depreciation rates, property, plant and equipment	5 years
Leasehold Improvements / Furniture [Member]
Residual value over its estimated useful life [Abstract]
Useful lives or depreciation rates, property, plant and equipment	5 years

Summary of significant accounting policies, Share capital and Initial Public Offering, Preferred Shares (Details) SFr / shares in Units, $ / shares in Units, SFr in Thousands, $ in Millions			1 Months Ended	12 Months Ended
	Apr. 15, 2016 SFr / shares shares	Oct. 23, 2015	Sep. 30, 2016	Dec. 31, 2017 SFr / shares	Dec. 31, 2016	Dec. 31, 2015 CHF (SFr) Class Increase Vote	Apr. 15, 2016 USD ($) $ / shares
Preferred Shares [Member]
Preferred Shares [Abstract]
Number of preferred shares classes outstanding \| Class						5
Conversion ratio of preferred shares to common shares			1
Number of separate capital increases \| Increase						5
Percentage of shares outstanding owned by Preferred shareholders						80.10%
Term of equity financing				13 years
Number of votes entitled for each preferred share \| Vote						1
Dividends paid to preferred shareholders \| SFr						SFr 0
Common Shares [Member]
Preferred Shares [Abstract]
Conversion ratio of preferred shares to common shares					1
Stock split ratio		250
Nominal value per share (in CHF per share)				SFr 0.02
Preferred Shares Series E [Member]
Preferred Shares [Abstract]
Nominal value per share (in CHF per share)	SFr 0.02
Private placement shares issued (in shares) \| shares	1,401,792
Private placement share price (in dollars per share) \| (per share)	SFr 0.02						$ 9.6384
Aggregate subscription amount \| $							$ 13.5

Summary of significant accounting policies, Share capital and Initial Public Offering (Details) $ / shares in Units, shares in Thousands, SFr in Thousands, $ in Millions			12 Months Ended
	Sep. 22, 2016 CHF (SFr) shares	Sep. 22, 2016 USD ($) $ / shares shares	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2015 CHF (SFr)
Initial Public Offering (IPO) [Abstract]
Proceeds from IPO net of underwriting fees \| SFr			SFr 0	SFr 69,388	SFr 0
Initial Public Offering [Member]
Initial Public Offering (IPO) [Abstract]
Shares issued (in shares)	6,000	6,000
IPO share price (in dollars per share) \| $ / shares		$ 11.00
Gross proceeds received	SFr 74,500	$ 75.9
Proceeds from IPO net of underwriting fees	69,300	$ 70.6
Increase in share premium \| SFr	SFr 64,200
Over-Allotment Option [Member]
Initial Public Offering (IPO) [Abstract]
Shares issued (in shares)	900	900
Common Shares [Member]
Initial Public Offering (IPO) [Abstract]
Shares issued (in shares)	6,900	6,900		6,900

Summary of significant accounting policies, Income taxes and Segment reporting (Details)	12 Months Ended
	Dec. 31, 2017 Segment
Income taxes [Abstract]
Tax loss carryforward period	7 years
Segment reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

Property, plant and equipment (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	SFr 1,120	SFr 500
Acquisitions	1,813	898
Depreciation expense	(580)	(278)	SFr (287)
Property, plant and equipment, end of period	2,353	1,120	500
Acquisition Cost [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	3,274	2,376
Property, plant and equipment, end of period	5,087	3,274	2,376
Accumulated Depreciation [Member]
Property, plant and equipment [Abstract]
Depreciation expense	(2,734)	(2,154)	(1,876)
Furniture [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	36	7
Acquisitions	4	38
Depreciation expense	(14)	(9)
Property, plant and equipment, end of period	26	36	7
Furniture [Member] \| Acquisition Cost [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	81	43
Property, plant and equipment, end of period	85	81	43
Furniture [Member] \| Accumulated Depreciation [Member]
Property, plant and equipment [Abstract]
Depreciation expense	(59)	(45)	(36)
Computers / IT [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	126	34
Acquisitions	271	126
Depreciation expense	(87)	(34)
Property, plant and equipment, end of period	310	126	34
Computers / IT [Member] \| Acquisition Cost [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	298	172
Property, plant and equipment, end of period	569	298	172
Computers / IT [Member] \| Accumulated Depreciation [Member]
Property, plant and equipment [Abstract]
Depreciation expense	(259)	(172)	(138)
Lab Equipment [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	934	429
Acquisitions	1,369	734
Depreciation expense	(453)	(229)
Property, plant and equipment, end of period	1,850	934	429
Lab Equipment [Member] \| Acquisition Cost [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	2,792	2,058
Property, plant and equipment, end of period	4,161	2,792	2,058
Lab Equipment [Member] \| Accumulated Depreciation [Member]
Property, plant and equipment [Abstract]
Depreciation expense	(2,311)	(1,858)	(1,629)
Leasehold Improvements [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	24	30
Acquisitions	169	0
Depreciation expense	(26)	(6)
Property, plant and equipment, end of period	167	24	30
Leasehold Improvements [Member] \| Acquisition Cost [Member]
Property, plant and equipment [Abstract]
Property, plant and equipment, beginning of period	103	103
Property, plant and equipment, end of period	272	103	103
Leasehold Improvements [Member] \| Accumulated Depreciation [Member]
Property, plant and equipment [Abstract]
Depreciation expense	SFr (105)	SFr (79)	SFr (73)

Financial Assets (Details) SFr in Thousands	12 Months Ended
Financial Assets (Details) SFr in Thousands	Dec. 31, 2017 CHF (SFr) Deposit	Dec. 31, 2016 CHF (SFr)
Financial Assets [Abstract]
Number of deposits in escrow accounts \| Deposit	2
Deposits in escrow accounts \| SFr	SFr 126	SFr 86

Prepaid expenses and accrued income (Details) - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepaid Expenses and Accrued Income [Line Items]
Prepaid expenses	SFr 1,440	SFr 1,278
Accrued income	2,799	889
Total	4,239	SFr 2,167
Biogen [Member]
Prepaid Expenses and Accrued Income [Line Items]
Accrued income	1,500
Janssen [Member]
Prepaid Expenses and Accrued Income [Line Items]
Accrued income	SFr 1,200

Other current receivables (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other current receivables [abstract]
Other receivables	SFr 691	SFr 182
Swiss VAT	112	320
Withholding tax	115	15
Total	SFr 918	SFr 517
Top of Range [Member]
Other current receivables [abstract]
Maturity period of assets	3 months

Cash and cash equivalents (Details) SFr in Thousands	Dec. 31, 2017 CHF (SFr) € / SFr $ / SFr	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2015 CHF (SFr)	Dec. 31, 2014 CHF (SFr)
Cash and cash equivalents [Abstract]
Cash	SFr 124,377	SFr 152,210	SFr 76,522	SFr 3,306
CHF [Member]
Cash and cash equivalents [Abstract]
Cash	103,272	41,322
EUR [Member]
Cash and cash equivalents [Abstract]
Cash	SFr 3,658	6,727
Translation rate into CHF \| € / SFr	1.169
USD [Member]
Cash and cash equivalents [Abstract]
Cash	SFr 17,447	SFr 104,161
Translation rate into CHF \| $ / SFr	0.976

Share capital (Details) SFr / shares in Units, $ / shares in Units, SFr in Thousands, $ in Millions			1 Months Ended	12 Months Ended
	Sep. 22, 2016 shares	Apr. 15, 2016 SFr / shares shares	Sep. 30, 2016	Dec. 31, 2017 CHF (SFr) shares SFr / shares	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2015 shares	Apr. 15, 2016 USD ($) $ / shares
Disclosure of classes of share capital [line items]
Share capital \| SFr				SFr 1,147	SFr 1,135
Options exercised				571,775	2,069,100	594,250
Restricted shares [Member]
Disclosure of classes of share capital [line items]
Shares issued (in shares)				4,023
Restricted Stock Units [Member]
Disclosure of classes of share capital [line items]
Shares vested (in shares)				5,998
Common Shares [Member]
Disclosure of classes of share capital [line items]
Shares outstanding (in shares)				57,355,188	56,773,392
Share capital \| SFr				SFr 1,147,104	SFr 1,135,468
Nominal value per share (in CHF per share) \| SFr / shares				SFr 0.02
Shares issued (in shares)	6,900,000				6,900,000
Options exercised					2,069,100
Additional shares issued upon conversion (in shares)					38,577,042
Conversion ratio of preferred shares to common shares					1
Preferred Shares Series E [Member]
Disclosure of classes of share capital [line items]
Nominal value per share (in CHF per share) \| SFr / shares		SFr 0.02
Private placement shares issued (in shares)		1,401,792
Private placement share price (in dollars/CHF per share) \| (per share)		SFr 0.02					$ 9.6384
Subscription amount \| $							$ 13.5
Preferred Shares [Member]
Disclosure of classes of share capital [line items]
Conversion ratio of preferred shares to common shares			1

Trade payables and accrued liabilities (Details) - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016
Trade payables and accrued liabilities [Abstract]
Trade payables and other payables	SFr 1,092	SFr 4,035
Accrued research and development costs	5,430	3,265
Accrued payroll expenses	2,420	1,419
Other accrued expenses	457	682
Deferred income	355	521
Total current liabilities	9,754	9,922
Accrual of performance-related remuneration	SFr 1,100	SFr 1,000

Deferred income (Details) SFr in Thousands, $ in Millions	12 Months Ended
Deferred income (Details) SFr in Thousands, $ in Millions	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 CHF (SFr)
Deferred income [Line Items]
Deferred income	SFr 521		SFr 355
Biogen [Member]
Deferred income [Line Items]
Deferred income	521		SFr 400
Upfront fees	SFr 1,500	$ 1.5

Long term financing obligation (Details) SFr in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2016 USD ($)
Long term financing obligation [Line Items]
Accrued interest - long-term	SFr 99	$ 100	SFr 0
Long-term financing obligation	SFr 395	400	SFr 0
Grants, LuMind Research Down Syndrome Foundation [Member]
Long term financing obligation [Line Items]
Funding commitment		$ 200		$ 200
Reimbursement percentage of funding commitment.	125.00%

Revenues (Details) € in Thousands, SFr in Thousands, $ in Millions	1 Months Ended					3 Months Ended			12 Months Ended
	Apr. 30, 2017 CHF (SFr)	Jul. 31, 2016 CHF (SFr)	May 31, 2016 CHF (SFr)	Apr. 30, 2016 CHF (SFr)	Jun. 30, 2012 CHF (SFr) Program	Dec. 31, 2017 CHF (SFr)	Mar. 31, 2017 CHF (SFr)	Jun. 30, 2016 CHF (SFr)	Dec. 31, 2017 CHF (SFr)	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2015 CHF (SFr)	Dec. 31, 2014 CHF (SFr) Company	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	May 31, 2014 EUR (€)
Revenues [Abstract]
Contract revenue									SFr 20,255	SFr 23,214	SFr 39,090
Total revenue									20,255	23,214	39,090
Revenues [Abstract]
Current deferred income						SFr 355			355	521
Collaboration Agreement of 2016, Biogen [Member]
Revenues [Abstract]
Current deferred income						400			SFr 400	521
Grant from Michael J. Fox Foundation [Member]
Revenues [Abstract]
Term of grant									1 year
Grant revenue recognized									SFr 95
Anti-Abeta Antibody in AD [Member] \| Collaboration Agreement of 2006, Genentech [Member]
Revenues [Abstract]
Cumulative payments received						70,100			SFr 70,100				$ 65
Period to provide notice of termination of agreement									3 months
Anti-Abeta Antibody in AD [Member] \| Collaboration Agreement of 2006, Genentech [Member] \| Top of Range [Member]
Revenues [Abstract]
Collaboration contract receivable \| $													$ 340
Anti-tau Antibody in AD [Member] \| Collaboration Agreement of 2012, Genentech [Member]
Revenues [Abstract]
Cumulative payments received						59,000			SFr 59,000
Milestone payment recognized								SFr 14,000
Milestone payment received		SFr 14,000				14,000					SFr 14,000
Number of additional indications \| Program					2
Period to provide notice of termination of agreement									3 months
Anti-tau Antibody in AD [Member] \| Collaboration Agreement of 2012, Genentech [Member] \| Bottom of Range [Member]
Revenues [Abstract]
Collaboration contract receivable					SFr 400,000
Tau Vaccine in AD [Member] \| Collaboration Agreement of 2014, Janssen Pharmaceuticals [Member]
Revenues [Abstract]
Cumulative payments received										SFr 1,500		SFr 25,900
Milestone payment received			SFr 4,900
Number of companies entered into joint research collaboration \| Company												2
Period of joint research collaboration									3 years
Joint research collaboration, subsequently amended period									5 years
Revenue recognition deferral period									12 months
Period to provide notice of termination of agreement									90 days
Tau-PET Imaging Agent in AD [Member] \| License and Collaboration Agreement of 2014, Piramal Imaging [Member]
Revenues [Abstract]
Collaboration contract receivable \| €															€ 157,000
Cumulative payments received \| €															€ 500
Milestone payment recognized							SFr 1,100
Milestone payment received						1,100
Revenue recognition deferral period									12 months
Collaboration contract receivable for clinical milestones \| €														€ 6,000
Collaboration contract receivable for regulatory, commercialization and sales milestones \| €														€ 150,000
Period to provide notice of termination of agreement									3 months
Alpha-synuclein and TDP-43 PET Tracer in AD [Member] \| Collaboration Agreement of 2016, Biogen [Member]
Revenues [Abstract]
Revenue recognition amortization period									12 months
Cumulative payments recognized	SFr 3,400			SFr 500
Current deferred income						355			SFr 355
Recombinant Protein Therapeutic Candidate [Member] \| Collaboration With Essex Bio-Technology Limited [Member]
Revenues [Abstract]
Cumulative payments recognized									SFr 78
Period for initial research plan									2 years
Recombinant Protein Therapeutic Candidate [Member] \| Collaboration With Essex Bio-Technology Limited [Member] \| Top of Range [Member]
Revenues [Abstract]
Collaboration contract receivable						SFr 750			SFr 750

Expenses by category (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
Expenses by category (Details) - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Research and Development [Abstract]
Operating expenses	SFr 23,822	SFr 18,767	SFr 10,763
Payroll expenses	8,552	6,450	5,879
Share-based compensation	289	557	407
Total research and development expenses	32,663	25,774	17,049
General and Administration [Abstract]
Operating expenses	3,857	3,168	1,377
Payroll expenses	4,984	3,969	1,908
Share-based compensation	1,290	759	132
Total general and administrative expenses	10,131	7,896	3,417
Financial Result, net [Abstract]
Interest income/ (expense)	184	36	55
Foreign currency remeasurement gain/(loss), net	(4,049)	3,443	1,598
Other finance income/(expense)	(7)	(119)	(7)
Finance result, net	SFr (3,872)	SFr 3,360	SFr 1,646

Related-party transactions (Details) SFr in Thousands	3 Months Ended		12 Months Ended
Related-party transactions (Details) SFr in Thousands	Dec. 31, 2017 shares	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2017 CHF (SFr) shares Individual	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2015 CHF (SFr) shares
Disclosure of transactions between related parties [line items]
Number of individuals, Board of Directors \| Individual			5
Number of individuals, Executive Management \| Individual			4
Short-term employee benefits \| SFr			SFr 2,463	SFr 2,251	SFr 1,776
Post-employment benefits \| SFr			166	154	124
Share-based compensation \| SFr			1,267	832	8
Total \| SFr			SFr 3,896	SFr 3,237	SFr 1,908
Number of options granted (in shares)			276,766	285,250	223,250
Restricted Stock Units [Member]
Disclosure of transactions between related parties [line items]
Number of restricted shares granted (in shares)			4,023	0	0
Executive Management [Member]
Disclosure of transactions between related parties [line items]
Number of options granted (in shares)			257,916	98,500	45,000
Executive Management [Member] \| Restricted Stock Units [Member]
Disclosure of transactions between related parties [line items]
Number of restricted shares granted (in shares)			95,957
Board of Directors [Member]
Disclosure of transactions between related parties [line items]
Number of options granted (in shares)			0	0	0
Board of Directors [Member] \| Restricted Stock Units [Member]
Disclosure of transactions between related parties [line items]
Number of restricted shares granted (in shares)			29,375
Former Chief Financial Officer [Member]
Disclosure of transactions between related parties [line items]
Number of options granted (in shares)		49,250
Fair value of options granted \| SFr		SFr 674		SFr 674
Board of Directors and Executive Management [Member] \| Restricted Stock Units [Member]
Disclosure of transactions between related parties [line items]
Number of restricted shares granted (in shares)	125,332			0	0

Income taxes (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
Income taxes (Details) - CHF (SFr) SFr in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income taxes [Abstract]
Deferred tax assets	SFr 0	SFr 0	SFr 0
Deferred tax liabilities	0	0	0
Income tax expense reconciled to Income / (loss) [Abstract]
Income / (loss) before income tax	(26,411)	(7,096)	20,270
Tax expense / (benefit) calculated at the statutory rate of 20.5% (21% for 2016 and 22% for 2015)	(5,420)	(1,504)	4,566
Effect of Swiss Tax Holidays	0	0	0
Permanent differences	40	(166)	0
Effect of unrecognized carry forward tax loss	0	0	(4,566)
Effect of unused tax losses and tax offsets not recognized as deferred tax assets	5,380	1,670	0
Effective income tax rate benefit / (expense)	SFr 0	SFr 0	SFr 0
Corporate tax rate	20.50%	21.00%	22.00%
Effective tax rate			0.00%

Income taxes, Unrecognized Deductible Temporary Differences, Unused Tax Losses and Unused Tax Credits (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecognized deductible temporary differences, unused tax losses and unused tax credits [Abstract]
Unrecognized deductible temporary differences, unused tax losses and unused tax credits	SFr 0	SFr 0	SFr 0
Unused tax losses and tax credits	67,501	40,505	31,866
Tax losses split by expiry date [Abstract]
Unused tax losses	62,575	36,707	29,079
Increase in tax losses available as an offset	25,900
Loss Expiry, December 31, 2017 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	0	0	0
Loss Expiry, December 31, 2018 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	2,175	2,175	2,175
Loss Expiry, December 31, 2019 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	16,566	16,566	16,566
Loss Expiry, December 31, 2020 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	10,338	10,338	10,388
Loss Expiry, December 31, 2021 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	0	0	0
Loss Expiry, December 31, 2022 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	0	0	0
Loss Expiry, December 31, 2023 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	7,628	7,628	0
Loss Expiry, December 31, 2024 [Member]
Tax losses split by expiry date [Abstract]
Unused tax losses	25,868	0	0
Tax Losses [Member]
Unrecognized deductible temporary differences, unused tax losses and unused tax credits [Abstract]
Unrecognized deductible temporary differences, unused tax losses and unused tax credits	62,575	36,707	29,079
Deductible Temporary Differences Related to the Retirement Benefit Plan [Member]
Unrecognized deductible temporary differences, unused tax losses and unused tax credits [Abstract]
Unrecognized deductible temporary differences, unused tax losses and unused tax credits	SFr 4,926	SFr 3,798	SFr 2,787

Retirement benefit plan (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined benefit pension plan amount recognized in balance sheet [Abstract]
Total liability	SFr (4,926)	SFr (3,798)
Domestic Defined Benefit Plans [Member]
Defined benefit pension plan amount recognized in balance sheet [Abstract]
Total liability	(4,926)	(3,798)	SFr (2,787)	SFr (2,410)
Net pension cost in statement of income [Abstract]
Service cost	912	742	641
Interest cost	81	75	101
Interest income	(55)	(56)	(76)
Impact of plan amendment	0	0	(584)
Net pension cost	938	761	82
Domestic Defined Benefit Plans [Member] \| Defined Benefit Obligation [Member]
Defined benefit pension plan amount recognized in balance sheet [Abstract]
Total liability	(14,278)	(11,596)	(9,439)
Net pension cost in statement of income [Abstract]
Service cost	912	742	641
Interest cost	81	75	101
Impact of plan amendment	0	0	(584)
Domestic Defined Benefit Plans [Member] \| Fair Value of Plan Assets [Member]
Defined benefit pension plan amount recognized in balance sheet [Abstract]
Total liability	9,352	7,798	6,652
Net pension cost in statement of income [Abstract]
Interest income	SFr (55)	SFr (56)	SFr (76)
Employee [Member]
Disclosure of net defined benefit liability (asset) [line items]
Contributions paid to the plan by computing percentage in salary	47.00%
Employer [Member]
Disclosure of net defined benefit liability (asset) [line items]
Contributions paid to the plan by computing percentage in salary	53.00%

Retirement benefit plan, Changes in Defined Benefit Obligation (Details) - Domestic Defined Benefit Plans [Member] - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in defined benefit obligation [Abstract]
Service cost	SFr (912)	SFr (742)	SFr (641)
Interest cost	(81)	(75)	(101)
Plan amendment	0	0	584
Defined Benefit Obligation [Member]
Changes in defined benefit obligation [Abstract]
Defined benefit obligation, beginning of period	(11,596)	(9,439)	(8,091)
Service cost	(912)	(742)	(641)
Interest cost	(81)	(75)	(101)
Change in demographic assumptions	0	(389)	0
Change in financial assumptions	0	(26)	(591)
Other actuarial gains / (losses)	(735)	(378)	(176)
Plan amendment	0	0	584
Benefit payments	(426)	(111)	(48)
Employees' contributions	(528)	(436)	(375)
Defined benefit obligation, end of period	SFr (14,278)	SFr (11,596)	SFr (9,439)

Retirement benefit plan, Changes in Fair Value of Plan Assets (Details) - Domestic Defined Benefit Plans [Member] - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in fair value of plan assets [Abstract]
Interest income	SFr 55	SFr 56	SFr 76
Employer's contributions	(590)	(511)	(441)
Fair Value of Plan Assets [Member]
Changes in fair value of plan assets [Abstract]
Fair value of plan assets, beginning of period	7,798	6,652	5,681
Interest income	55	56	76
Employees' contributions	528	436	375
Employer's contributions	590	511	441
Benefits payments	426	111	48
Plan assets gains/(losses)	(45)	32	31
Fair value of plan assets, end of period	9,352	SFr 7,798	SFr 6,652
Fair Value of Plan Assets [Member] \| 2018 [Member]
Changes in fair value of plan assets [Abstract]
Employer's contributions	SFr 630

Retirement benefit plan, Change in Net Definied Benefit Liability (Details) SFr in Thousands	12 Months Ended
	Dec. 31, 2017 CHF (SFr) yr	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2015 CHF (SFr)
Change in net defined benefit liability [Abstract]
Net defined benefit liabilities, beginning of period	SFr 3,798
Re-measurement through other comprehensive income	780	SFr 761	SFr 736
Net defined benefit liabilities, end of period	4,926	3,798
Domestic Defined Benefit Plans [Member]
Change in net defined benefit liability [Abstract]
Net defined benefit liabilities, beginning of period	3,798	2,787	2,410
Net pension cost through statement of income	938	761	82
Re-measurement through other comprehensive income	780	761	736
Employer's contribution	(590)	(511)	(441)
Net defined benefit liabilities, end of period	SFr 4,926	SFr 3,798	SFr 2,787
Weighted average duration period for defined benefit obligation \| yr	20.5

Retirement benefit plan, Actuarial Assumptions and Sensitivity Analysis (Details) - Domestic Defined Benefit Plans [Member] - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Actuarial assumptions [Abstract]
Discount rate	0.70%	0.70%	1.25%
Rate of future increase in compensations	1.50%	1.50%	1.50%
Rate of future increase in current pensions	0.50%	0.50%	0.50%
Mortality and disability rates	BVG 2015G	BVG 2015G	BVG 2010G
+0.5% Increase [Member]
Sensitivity analysis [Abstract]
Percentage increase in actuarial assumption	0.50%
-0.5% Decrease [Member]
Sensitivity analysis [Abstract]
Percentage decrease in actuarial assumption	0.50%
Discount Rate [Member] \| +0.5% Increase [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	SFr 12,707
Impact on the net defined benefit obligation	1,571
Discount Rate [Member] \| -0.5% Decrease [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	15,849
Impact on the net defined benefit obligation	(1,571)
Future Salary Increase [Member] \| +0.5% Increase [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	14,449
Impact on the net defined benefit obligation	(171)
Future Salary Increase [Member] \| -0.5% Decrease [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	14,121
Impact on the net defined benefit obligation	157
Future Pension Cost [Member] \| +0.5% Increase [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	14,989
Impact on the net defined benefit obligation	(711)
Future Pension Cost [Member] \| -0.5% Decrease [Member]
Sensitivity analysis [Abstract]
Defined benefit obligation	13,564
Impact on the net defined benefit obligation	SFr 714

Share-based compensation, Plans Outstanding (Details)	12 Months Ended
Share-based compensation, Plans Outstanding (Details)	Dec. 31, 2017 shares Plan	Dec. 31, 2016 shares	Dec. 31, 2015 shares
Share-based compensation [Abstract]
Number of equity-based instrument plans \| Plan	4
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	276,766	285,250	223,250
Contractual life of options	10 years
Stock Option Plan A [Member]
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	362,750
Contractual life of options	15 years 6 months
Stock Option Plan B [Member]
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	819,000
Contractual life of options	10 years 6 months
Stock Option Plan C1 [Member]
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	6,775,250
Vesting conditions	4 years
Contractual life of options	10 years
2016 Share Option and Incentive Plan [Member] \| Executives and Directors [Member]
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	257,916
Vesting conditions	4 years
Contractual life of options	10 years
2016 Share Option and Incentive Plan [Member] \| Employees [Member]
Share-based plans outstanding [Abstract]
Number of options awarded (in shares)	18,850
Vesting conditions	4 years
Contractual life of options	10 years

Share-based compensation, Weighted Average Exercise Prices (Details)	12 Months Ended
	Dec. 31, 2017 CHF (SFr) shares yr	Dec. 31, 2016 CHF (SFr) shares yr	Dec. 31, 2015 CHF (SFr) shares yr	Dec. 31, 2014 yr
Number of Options [Abstract]
Outstanding at beginning of period (in shares) \| shares	1,687,900	3,597,000	4,006,500
Forfeited during the year (in shares) \| shares	(1,750)	(106,000)	(23,250)
Cancelled during the year (in shares) \| shares	(31,250)	(19,250)	(15,250)
Exercised during the year (in shares) \| shares	(571,775)	(2,069,100)	(594,250)
Granted during the year (in shares) \| shares	276,766	285,250	223,250
Outstanding at end of period (in shares) \| shares	1,359,891	1,687,900	3,597,000
Exercisable (in shares) \| shares	900,474	1,284,525	3,032,500
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in CHF per share) \| SFr	SFr 0.14548	SFr 0.14548	SFr 0.21668
Forfeited during the year (in CHF per share) \| SFr	0.14548	0.14548	0.14548
Cancelled during the year (in CHF per share) \| SFr	0.14548	0.14548	0.14548
Exercised during the year (in CHF per share) \| SFr	0.14548	0.14548	0.14548
Granted during the year (in CHF per share) \| SFr	9.70	0.14548	0.14548
Outstanding at end of period (in CHF per share) \| SFr	2.09	0.14548	0.14548
Exercisable (in CHF per share) \| SFr	SFr 0.39	SFr 0.14548	SFr 0.14548
Weighted Average Remaining Term (Years) [Abstract]
Weighted average remaining term (years) \| yr	5.8	5.6	3.6	4.5
Exercisable \| yr	4.3	6.5	3.4

Share-based compensation, Summary Information (Details)	3 Months Ended	12 Months Ended
Share-based compensation, Summary Information (Details)	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2017 CHF (SFr) yr	Dec. 31, 2016 CHF (SFr) shares yr	Dec. 31, 2015 CHF (SFr) yr	Dec. 31, 2014 CHF (SFr)
Share-based compensation [Abstract]
Exercise price for outstanding options (in CHF per share)	SFr 0.14548	SFr 2.09	SFr 0.14548	SFr 0.14548	SFr 0.21668
Weighted average fair value, options granted (in CHF per share)		7.29	5.85	1.77
Fair values of options granted (in CHF per share)			0.14548	0.14548
Weighted average share price of options granted (in CHF per share)		SFr 8.77	SFr 5.96	SFr 1.91
Risk free interest rate		0.00%	0.00%	0.00%
Volatility rate		80.00%	80.00%	50.00%
Expected duration \| yr		6	6	6
Expiry period of options		10 years
Weighted average share price of common share options exercised (in CHF per share)		SFr 10.53	SFr 6.22	SFr 1.91
Expense charged against the income statement		1,579,000	SFr 1,317,000	SFr 540,000
Incremental fair value amount		238,000
Bottom of Range [Member]
Share-based compensation [Abstract]
Exercise price for outstanding options (in CHF per share)		0.14548
Fair values of options granted (in CHF per share)		9.53
Top of Range [Member]
Share-based compensation [Abstract]
Exercise price for outstanding options (in CHF per share)		12.00
Fair values of options granted (in CHF per share)		SFr 12.00
Former Chief Financial Officer [Member]
Share-based compensation [Abstract]
Forfeited during the year (in shares) \| shares			98,500
Granted during the year (in shares) \| shares	49,250
Grant date fair value of the replacement award	SFr 674,000		SFr 674,000

Share-based compensation, Non-vested Share Awards (Details)	12 Months Ended
	Dec. 31, 2017 CHF (SFr) shares	Dec. 31, 2016 CHF (SFr) shares	Dec. 31, 2015 CHF (SFr) shares
Non-vested Share Awards [Member]
Share-based payment arrangement [Abstract]
Number of non-vested share awards granted (in shares)	129,355	0	0
Number of non-vested shares [Abstract]
Non-vested (in shares)	0
Forfeited during the year (in shares)	0
Cancelled during the year (in shares)	0
Exercised during the year (in shares)	0
Granted during the year (in shares)	129,355	0	0
Non-vested (in shares)	122,014	0
Vested (in shares)	7,341
Weighted Average grant date fair value [Abstract]
Non-vested (in CHF per share) \| SFr	SFr 0	SFr 0
Forfeited during the year (in CHF per share) \| SFr	0
Cancelled during the year (in CHF per share) \| SFr	0
Exercised during the year (in CHF per share) \| SFr	0
Granted during the year (in CHF per share) \| SFr	9.62
Non-vested (in CHF per share) \| SFr	9.59	SFr 0	SFr 0
Vested (in CHF per share) \| SFr	SFr 10.06
Restricted Share Awards [Member]
Share-based payment arrangement [Abstract]
Number of non-vested share awards granted (in shares)	4,023
Vesting conditions	2 years 9 months
Contractual life of non-vested share awards	10 years
Number of non-vested shares [Abstract]
Granted during the year (in shares)	4,023
Restricted Stock Units [Member]
Share-based payment arrangement [Abstract]
Number of non-vested share awards granted (in shares)	4,023	0	0
Number of non-vested shares [Abstract]
Exercised during the year (in shares)	5,998
Granted during the year (in shares)	4,023	0	0
Restricted Stock Units [Member] \| Directors [Member]
Share-based payment arrangement [Abstract]
Number of non-vested share awards granted (in shares)	29,375
Vesting conditions	1 year
Contractual life of non-vested share awards	10 years
Number of non-vested shares [Abstract]
Granted during the year (in shares)	29,375
Restricted Stock Units [Member] \| Executives [Member]
Share-based payment arrangement [Abstract]
Number of non-vested share awards granted (in shares)	95,957
Vesting conditions	4 years
Contractual life of non-vested share awards	10 years
Number of non-vested shares [Abstract]
Granted during the year (in shares)	95,957

Commitments and contingencies (Details) - CHF (SFr) SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Commitments and contingencies [Abstract]
Commitments	SFr 12,372	SFr 10,799
External research projects	SFr 9,400
Notice period for cancellation of rental contract	6 months
Lease expense	SFr 500
Rental contracts amount	200
Royalty payment obligation	400
Within One Year [Member]
Commitments and contingencies [Abstract]
Commitments	9,686	9,175
Between One and Three Years [Member]
Commitments and contingencies [Abstract]
Commitments	2,546	1,624
Between Three and Five Years [Member]
Commitments and contingencies [Abstract]
Commitments	140	0
More Than Five Years [Member]
Commitments and contingencies [Abstract]
Commitments	SFr 0	SFr 0

Earnings per share (Details) - CHF (SFr) SFr / shares in Units, SFr in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share [Abstract]
Net income / (loss) attributable to owners of the Company	SFr (26,411)	SFr (7,096)	SFr 20,270
Earnings per share (EPS) [Abstract]
Basic, income / (loss) for the period attributable to equity holders (in CHF per share)	SFr (0.46)	SFr (0.14)	SFr 0.47
Diluted, income / (loss) for the period attributable to equity holders (in CHF per share)	SFr (0.46)	SFr (0.14)	SFr 0.44
Weighted-average number of shares used to compute EPS basic (in shares)	57,084,295	50,096,859	43,412,250
Weighted-average number of shares used to compute EPS fully diluted (in shares)	57,084,295	50,096,859	46,043,198
Antidilutive shares to be issued (in shares)	1,463,056	1,687,900
Weighted average number of equity awards outstanding (in shares)	1,582,612	2,784,245

Financial instruments and risk management (Details) SFr in Thousands	12 Months Ended
	Dec. 31, 2017 CHF (SFr) Bank	Dec. 31, 2016 CHF (SFr)	Dec. 31, 2015 CHF (SFr)
Financial assets and liabilities [Abstract]
Financial assets	SFr 125,295	SFr 152,727
Financial liabilities	9,794	9,401
Financial risks [Abstract]
Gain (loss) in finance income/(expense), net	(4,049)	3,443	SFr 1,598
Foreign Currency Exchange Risk [Member]
Financial risks [Abstract]
Gain (loss) in finance income/(expense), net	SFr (4,200)	3,400	SFr 1,600
Percentage exchange rate strengthened	10.00%
Percentage exchange rate weakened	10.00%
Net loss for period decrease, result of foreign exchange rate increase	SFr 2,100	10,900
Net loss for period increase, result of foreign exchange rate decrease	SFr 2,100	10,900
Credit Risk [Member]
Financial risks [Abstract]
Number of banks holding cash and cash equivalents \| Bank	1
Liquidity Risk [Member]
Financial risks [Abstract]
Cash position rolling forecast period	18 months
Long-Term Financing Obligation [Member]
Financial assets and liabilities [Abstract]
Financial liabilities	SFr 395	0
Trade and Other Payables [Member]
Financial assets and liabilities [Abstract]
Financial liabilities	1,092	4,035
Accrued Expenses [Member]
Financial assets and liabilities [Abstract]
Financial liabilities	8,307	5,366
Other Current Receivables [Member]
Financial assets and liabilities [Abstract]
Financial assets	918	517
Cash and Cash Equivalents [Member]
Financial assets and liabilities [Abstract]
Financial assets	SFr 124,377	SFr 152,210

Post balance sheet events (Details) - Subsequent Event [Member] $ in Thousands	Feb. 02, 2018 USD ($) ft²
Post balance sheet events [Abstract]
Additional lease space \| ft²	4,300
Purchase of lab equipment \| $	$ 750