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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Mar. 02, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	EIGR
Entity Registrant Name	Eiger BioPharmaceuticals, Inc.
Entity Central Index Key	0001305253
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		10,526,599
Entity Public Float			$ 36,711,134

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 32,035	$ 27,756
Short-term marketable securities	9,744	32,180
Prepaid expenses and other current assets	712	581
Total current assets	42,491	60,517
Property and equipment, net	79	76
Other assets	312	143
Total assets	42,882	60,736
Current liabilities:
Accounts payable	3,183	2,639
Accrued liabilities	2,084	2,649
Current portion of long term debt	2,002
Total current liabilities	7,269	5,288
Long term debt, net	13,091	14,727
Total liabilities	20,360	20,015
Commitments and contingencies (Note 15)
Stockholders’ equity:
Common stock, $0.001 par value, 200,000,000 shares authorized as of December 31, 2017 and 2016; 10,526,599 and 8,356,659 shares issued and outstanding as of December 31, 2017 and 2016, respectively	11	8
Additional paid-in capital	141,320	117,086
Accumulated other comprehensive loss	(3)	(15)
Accumulated deficit	(118,806)	(76,358)
Total stockholders’ equity	22,522	40,721
Total liabilities and stockholders’ equity	$ 42,882	$ 60,736

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	10,526,599	8,356,659
Common stock, shares outstanding	10,526,599	8,356,659

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development	$ 29,519	$ 33,014	$ 8,117
General and administrative	12,001	13,106	4,855
Total operating expenses	41,520	46,120	12,972
Loss from operations	(41,520)	(46,120)	(12,972)
Interest expense	(1,524)	(690)	(350)
Interest income	410	97
Other income (expense), net	186	(374)
Net loss	$ (42,448)	$ (47,087)	$ (13,322)
Net loss per share, basic and diluted	$ (4.86)	$ (7.84)	$ (62.19)
Weighted-average common shares outstanding, basic and diluted	8,727,935	6,007,027	214,228

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (42,448)	$ (47,087)	$ (13,322)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities, net	12	(15)
Comprehensive loss	$ (42,436)	$ (47,102)	$ (13,322)

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Eiccose LLC [Member]	Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Eiccose LLC [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Eiccose LLC [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2014	$ 531					$ 1,114			$ (15,949)
Temporary equity, Beginning balance at Dec. 31, 2014			$ 15,366
Beginning Balance, Shares at Dec. 31, 2014				193,850
Temporary equity, Beginning balance, Shares at Dec. 31, 2014			1,519,274
Issuance of stock	7,201		$ 7,201
Issuance of stock, Shares			1,089,828
Issuance of common stock in connection with a license and asset purchase agreement	211					211
Issuance of common stock in connection with a license and asset purchase agreement, Shares				15,378
Issuance of common stock upon stock option exercises, Shares				64,765
Stock-based compensation expense	227					227
Net loss	(13,322)								(13,322)
Ending Balance at Dec. 31, 2015	(5,152)					1,552			(29,271)
Temporary equity, Ending balance at Dec. 31, 2015			$ 22,567
Ending Balance, Shares at Dec. 31, 2015				273,993
Temporary equity, Ending balance, Shares at Dec. 31, 2015			2,609,102
Issuance of common stock upon private placement, net of $1,300 of issuance cost	32,108			$ 2		32,106
Issuance of common stock upon private placement, net of $1,300 of issuance cost, Shares				1,954,390
Issuance of common stock upon conversion of convertible promissory note	6,129					6,129
Issuance of common stock upon conversion of convertible promissory note, Shares				350,040
Conversion of preferred stock into common stock, Temporary equity			$ (22,567)
Conversion of preferred stock into common stock, Temporary equity shares			(2,609,102)
Issuance of common stock upon exercise of warrants	1,057					1,057
Issuance of common stock upon exercise of warrants, Shares				61,254
Issuance of common stock to Eiccose upon private placement		$ 1,661					$ 1,661
Issuance of common stock to Eiccose upon private placement, Shares					96,300
Conversion of preferred stock into common stock				$ 3		22,564
Conversion of preferred stock into common stock, Shares				2,609,102
Issuance of common stock upon reverse merger	27,390			$ 2		27,388
Issuance of common stock upon reverse merger, Shares				1,596,959
Issuance of stock	18,229			$ 1		18,228
Issuance of stock, Shares				1,250,000
Issuance of common stock in connection with a license and asset purchase agreement	3,172					3,172
Issuance of common stock in connection with a license and asset purchase agreement, Shares				157,587
Issuance of common stock upon stock option exercises	39					39
Issuance of common stock upon stock option exercises, Shares				7,034
Stock-based compensation expense	3,190					3,190
Unrealized gain (loss) on marketable securities, net	(15)							$ (15)
Net loss	(47,087)								(47,087)
Ending Balance at Dec. 31, 2016	$ 40,721			$ 8		117,086		(15)	(76,358)
Ending Balance, Shares at Dec. 31, 2016	8,356,659			8,356,659
Issuance of stock	$ 19,800			$ 3		19,797
Issuance of stock, Shares				2,143,525
Issuance of common stock upon ESPP purchase	142					142
Issuance of common stock upon ESPP purchase, Shares				16,186
Issuance of common stock upon stock option exercises	$ 52					52
Issuance of common stock upon stock option exercises, Shares	10,229			10,229
Stock-based compensation expense	$ 4,243					4,243
Unrealized gain (loss) on marketable securities, net	12							12
Net loss	(42,448)								(42,448)
Ending Balance at Dec. 31, 2017	$ 22,522			$ 11		$ 141,320		$ (3)	$ (118,806)
Ending Balance, Shares at Dec. 31, 2017	10,526,599			10,526,599

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Series A-1 Convertible Preferred Stock [Member]
Issuance of common stock, issuance stock			$ 22
Private Placement [Member]
Issuance of common stock, issuance stock		$ 1,300
Initial Public Offering [Member]
Issuance of common stock, issuance stock	$ 376	$ 1,800

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net loss	$ (42,448)	$ (47,087)	$ (13,322)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	41	23	11
Amortization of premiums on marketable securities	(53)	(41)
Stock-based compensation	4,243	3,190	227
Non-cash interest expense	366	685	350
Gain on intellectual property sale	(200)
Issuance of common stock in connection with a license and asset purchase agreement		3,172	211
Change in fair value of obligation to issue shares to Eiccose		204	1,457
Change in fair value of warrants liability		165
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(131)	326	(685)
Other non-current assets	(169)	(89)	(46)
Accounts payable	544	699	1,881
Accrued liabilities	(565)	783	782
Net cash used in operating activities	(38,372)	(37,970)	(9,134)
Investing Activities
Purchase of marketable securities	(24,524)	(34,154)
Proceeds from maturities of marketable securities	47,025	2,000
Proceeds from intellectual property sale	200
Cash received from merger transaction		28,018
Purchase of property and equipment	(44)	(58)	(45)
Net cash provided by (used in) investing activities	22,657	(4,194)	(45)
Financing Activities
Proceeds from issuance of common stock upon public offering, net of issuance cost	19,800	18,229
Proceeds from borrowings in connection with term loan, net of issuance cost		14,759
Proceeds from issuance of common stock upon private placement, net of issuance cost		32,108
Proceeds from issuance of common stock upon ESPP purchase	142
Proceeds from issuance of common stock upon options exercises	52	39
Proceeds from issuance of common stock upon warrants exercises		7
Proceeds from issuance of convertible promissory note, net of issuance costs			5,979
Proceeds from issuance of preferred stock, net of issuance costs			7,201
Net cash provided by financing activities	19,994	65,142	13,180
Net increase in cash and cash equivalents	4,279	22,978	4,001
Cash and cash equivalents at beginning of period	27,756	4,778	777
Cash and cash equivalents at end of period	$ 32,035	27,756	4,778
Non-cash investing and financing activities:
Conversion of warrant liability to common stock upon private placement		1,050
Issuance of common stock		3,172	211
Non-cash net liabilities assumed in reverse merger		671
Conversion of convertible promissory note to common stock upon private placement		6,129
Conversion of preferred stock to common stock upon reverse merger		22,567
Issuance of warrants in connection with convertible promissory note			$ 885
Eiccose LLC [Member]
Non-cash investing and financing activities:
Issuance of common stock		$ 1,661

Description of Business

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Description of Business

1.	Description of Business

Eiger BioPharmaceuticals, Inc. (the “Company” or “Eiger”) was incorporated in the State of Delaware on November 6, 2008. The Company is a clinical-stage biopharmaceutical company committed to bringing to market novel products for the treatment of rare diseases. The Company has built a diverse portfolio of well-characterized product candidates with the potential to address diseases for which the unmet medical need is high, the biology for treatment is clear, and for which an effective therapy is urgently needed. The Company’s principal operations are based in Palo Alto, California and it operates in one segment.

Reverse Merger

On March 22, 2016, Eiger completed its merger with Celladon Corporation (“Celladon”) in accordance with the terms of the Agreement and Plan of Merger and Reorganization, dated November 18, 2015 (the “Merger Agreement”), by and among Celladon, Celladon Merger Sub, Inc. (“Merger Sub”) and Eiger (the “Merger”). Pursuant to the Merger Agreement, Merger Sub merged with and into Eiger, with Eiger becoming a wholly-owned subsidiary of Celladon and the surviving corporation of the Merger. Pursuant to the terms and subject to the conditions set forth in the Merger Agreement, Eiger stockholders became the majority stockholders of the surviving company. In connection with, and immediately prior to, the closing of the Merger, on March 22, 2016, Celladon filed an amendment to its amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to affect a fifteen-for-one reverse stock split of its common stock (the “Reverse Stock Split”). In connection with and immediately following the consummation of the Merger, on March 22, 2016, Celladon filed an amendment to its amended and restated certificate of incorporation with the Secretary of State of the State of Delaware to change its name to Eiger BioPharmaceuticals, Inc. The Company’s shares of common stock listed on the NASDAQ Global Market, previously trading through the close of business on Tuesday, March 22, 2016 under the ticker symbol “CLDN,” commenced trading on the NASDAQ Global Market, on a post-reverse stock split adjusted basis, under the ticker symbol “EIGR” on March 23, 2016. On March 22, 2016, a Certificate of Merger was filed with the Secretary of State of the State of Delaware to affect the Merger of Merger Sub with and into Eiger. See Note 5 for further details.

The Company, or Eiger, as used in the accompanying notes to the consolidated financial statements, refers to Private Eiger prior to the completion of the Merger and Public Eiger subsequent to the completion of the Merger.

Reverse Stock Split and Exchange Ratio

On March 22, 2016, and prior to the closing of the Merger, Celladon completed a fifteen-for-one reverse stock split. As a result of the reverse stock split, every fifteen shares of Celladon common stock outstanding immediately prior to the Merger were combined and reclassified into one share of Celladon common stock. No fractional shares were issued in connection with the reverse stock split.

The holders of shares of Eiger common stock outstanding immediately prior to the Merger received approximately 0.09 shares of Celladon common stock in exchange for each share of Eiger common stock in the Merger. Following the reverse stock split and the Merger on March 22, 2016, the combined company had 6,945,401 shares of common stock outstanding.

The accompanying consolidated financial statements and notes to the consolidated financial statements give retroactive effect to the reverse stock split for all periods presented.

Liquidity

As of December 31, 2017, the Company had $32.0 million of cash and cash equivalents and $9.7 million of short-term marketable securities. In addition, the Company had an accumulated deficit of $118.8 million and negative cash flows from operating activities. The Company expects to continue to incur losses for the next several years.

Management believes that the currently available resources will be sufficient to fund its operations, focused on completing its three ongoing Phase 2 development programs and initial preparations for advancing its lead program into Phase 3, for at least the next 12 months following the issuance date of these consolidated financial statements. However, if the Company’s anticipated operating results are not achieved in future periods, management believes that planned expenditures will need to be reduced in order to extend the time period over which the then-available resources would be able to fund the Company’s operations.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation and Consolidation

The consolidated financial statements include the accounts of Eiger BioPharmaceuticals, Inc. and its wholly owned subsidiary EB Pharma LLC, have been prepared in conformity with accounting principles generally accepted in the United States of America, (“U.S. GAAP”). All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to accrued research and development expenses, stock-based compensation and income taxes. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Concentrations of Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consists of cash, cash equivalents and investments. The Company’s cash is held by a financial institution in the United States. Amounts on deposit may at times exceed federally insured limits. Management believes that the financial institution is financially sound, and accordingly, minimal credit risk exists with respect to the financial institution.

For each product candidate, the Company relies on one supply chain for each of the four product candidates. If any of the single source suppliers in any of the supply chains fail to satisfy the Company’s requirements on a timely basis, it could suffer delays in its clinical development programs and activities, which could adversely affect its operating results.

Cash and Cash Equivalents

Cash and cash equivalents include all cash balances and highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consists primarily of amounts invested in money market funds held at financial institutions and corporate debt securities. The recorded carrying amount of cash equivalents approximates their fair value.

Short-Term Marketable Securities

Short-term securities consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. All short-term marketable securities are carried at fair value based upon quoted market prices. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated other comprehensive loss. The cost of available-for-sale securities sold is based on the specific-identification method. Realized gains and losses on the sale of marketable securities are determined using the specific-identification method and recorded in other income (expense), net on the accompanying consolidated statements of operations.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Depreciation expense is computed using the straight-line method over the estimated useful lives of the assets. Depreciation begins at the time the asset is placed into service. Maintenance and repairs are charged to operations as incurred. Property and equipment purchased for specific research and development projects with no alternative uses are expensed as incurred.

The useful lives of the property and equipment are as follows:

Lab equipment		5 years
Computer equipment and software		3 years

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The Company assesses the recoverability of long-lived assets by determining whether or not the carrying value of such assets will be recovered through undiscounted expected future cash flows. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired asset. Through December 31, 2017, the Company has not impaired any long-lived assets.

Accrued Research and Development Expenses

The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced, and includes these costs in accrued liabilities in the consolidated balance sheets and within research and development expense in the consolidated statements of operations. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. The Company makes judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities.

Deferred Financing Costs

Financing costs incurred with securing a term debt are recorded in the Company’s consolidated balance sheets as an offset to the term debt and amortized to interest expense in the Company’s consolidated statements of operations over the contractual life of the loan using the effective interest method.

Research and Development Costs

Research and development costs are expensed as incurred and consist of payroll expenses, stock-based compensation expense, lab supplies and allocated facility costs, as well as fees paid to third parties that conduct certain research and development activities on the Company’s behalf. Amounts incurred in connection with license and asset purchase agreements are also included in research and development expense.

Stock-Based Compensation

Stock-based awards to employees and directors, including stock options, are recorded at fair value as of the grant date using the Black-Scholes option pricing model and recognized as expense on a straight line-basis over the employee’s or director’s requisite service period (generally the vesting period). The determination of fair value for stock-based awards on the date of grant using an option pricing model requires management to make certain assumptions regarding subjective variables.

Stock-based awards and stock options issued to non-employee consultants are recorded at fair value and remeasured at the end of each period as they vest using the Black-Scholes option pricing model. Expense is recognized over the vesting period which is generally the same as the service period.

Income Taxes

The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.

The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to unrecognized tax benefits.

Internal Revenue Code Section 382 limits the use of net operating loss and tax credit carryforwards in certain situations where changes occur in the stock ownership of a company. In the event that the Company had a change of ownership, utilization of the net operating loss and tax credit carryforwards may be restricted.

Comprehensive Loss

Comprehensive loss represents all changes in stockholders' equity (deficit) except those resulting from and distributions to stockholders. The Company’s unrealized gains and losses on available-for-sale securities represent the only component of other comprehensive loss that are excluded from the reported net loss and that are presented in the consolidated statements of comprehensive loss.

Net Loss per Share

Basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive.

The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net loss per share because including such securities would be anti-dilutive (in common stock equivalent shares):

	December 31,
	2017		2016		2015
Options to purchase common stock		1,467,051		1,212,044		254,058
Warrants to purchase common stock		10,180		10,180		—
Convertible preferred stock		—		—		2,609,102
Total		1,477,231		1,222,224		2,863,160

Recent Accounting Pronouncements

In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities. ASU No. 2016-01 supersedes and amends the guidance to classify equity securities with readily determinable fair values into different categories (that is, trading or available-for-sale) and require equity securities to be measured at fair value with changes in the fair value recognized through net income. The amendments allow equity investments that do not have readily determinable fair values to be remeasured at fair value either upon the occurrence of an observable price change or upon identification of an impairment. The amendments also require enhanced disclosures about those investments. ASU No. 2016-01 is effective for annual reporting beginning after December 15, 2017, including interim periods within the year of adoption, and calls for prospective application. The Company is currently in the process of evaluating the impact that the standard will have on its consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires lessees to recognize most leases on their balance sheet. The standard requires use of the modified retrospective transition method, with elective relief, which requires application of the guidance for all periods presented. The new standard will be effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. The Company is currently in the process of evaluating the impact that the standard will have on its consolidated financial statements.

In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which is intended to simplify several aspects of the accounting for employee share-based payment transactions, including the accounting and reporting of income taxes, the determination of forfeiture rates, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for fiscal years and interim periods within those years beginning after December 15, 2016 and early adoption is permitted. The Company adopted this ASU in the first quarter of 2017. As a result of adopting this standard, the Company made an accounting policy election to account for forfeitures as they occur. This change did not have a material impact on the Company’s consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326). The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. The standard is effective for fiscal years and interim periods beginning after December 15, 2019. Early adoption is permitted for all periods beginning after December 15, 2018. The Company is currently in the process of evaluating the impact the standard will have on its consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. ASU 2016-15 identifies how certain cash receipts and cash payments are presented and classified in the Statement of Cash Flows. The standard is effective for fiscal years and interim periods beginning after December 15, 2017. The standard should be applied retrospectively and early adoption is permitted, including adoption in an interim period. The Company does not expect the standard to have a material impact on its consolidated financial statements.

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually). At December 31, 2017 and 2016, the carrying amount of prepaid expenses and other current assets, accounts payable and accrued liabilities approximated their estimate fair value due to their relatively short maturities. Management believes the terms of long term debt reflects current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company’s debt approximated its fair value.

Assets and liabilities recorded at fair value on a recurring basis in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1: Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level 2: Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3: Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.

The Company’s money market funds are classified as Level 1 because they are valued using quoted market prices. The Company’s marketable securities consist of available-for-sale securities and are classified as Level 2 because their value is based on valuations using significant inputs derived from or corroborated by observable market data.

There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the periods presented.

The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands):

	December 31, 2017
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	19,612	$	—	$	—	$	19,612
Corporate debt securities		—		6,501		—		6,501
Commercial paper		—		3,243		—		3,243
Total	$	19,612	$	9,744	$	—	$	29,356

	December 31, 2016
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	9,657	$	—	$	—	$	9,657
Corporate debt securities		—		11,469		—		11,469
Commercial paper		—		22,891		—		22,891
Total	$	9,657	$	34,360	$	—	$	44,017

There were no financial liabilities as of December 31, 2017.

The following table provides a reconciliation of liabilities measured at fair value using Level 3 significant unobservable inputs as of December 31, 2016 (in thousands):

	Year Ended December 31, 2016
Balance at December 31, 2015	$	2,342
Change in fair value of common stock warrants and obligation to issue common stock to Eiccose ⁽¹⁾		369
Settlement of warrant liability upon exercise of common stock warrants		(1,050	)
Settlement of Eiccose obligation upon issuance of common stock		(1,661	)
Balance at December 31, 2016	$	—

(1)	Changes in fair value of the obligation to issue common stock and the common stock warrant liability are recorded in other income (expense), net on the accompanying consolidated statements of operations.

The following tables summarize the estimated value of the Company’s cash equivalents and marketable securities and the gross unrealized holding gains and losses (in thousands):

	December 31, 2017
	Amortized cost		Unrealized gain		Unrealized loss			Estimated Fair Value
Cash equivalents:
Money market funds	$	19,612	$	—	$	—		$	19,612
Total cash equivalents	$	19,612	$	—	$	—		$	19,612
Marketable securities:
Corporate debt securities	$	6,503	$	—	$	(2	)	$	6,501
Commercial paper		3,244		—		(1	)		3,243
Total marketable securities	$	9,747	$	—	$	(3	)	$	9,744

	December 31, 2016
	Amortized cost		Unrealized gain		Unrealized loss			Estimated Fair Value
Cash equivalents:
Money market funds	$	9,657	$	—	$	—		$	9,657
Corporate debt securities		2,180		—		—			2,180
Total cash equivalents	$	11,837	$	—	$	—		$	11,837
Marketable securities:
Corporate debt securities	$	9,294	$	—	$	(5	)	$	9,289
Commercial paper		22,901		3		(13	)		22,891
Total marketable securities	$	32,195	$	3	$	(18	)	$	32,180

As of December 31, 2017, the contractual maturity of the available-for-sale marketable securities is less than one year. The Company periodically reviews the available-for-sale investments for other-than-temporary impairment loss. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, it also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. As of December 31, 2017, the Company did not recognize any other-than-temporary impairment losses. All marketable securities with unrealized losses have been in a loss position for less than twelve months.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2017

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

4.	Balance Sheet Components

Property and Equipment, Net

Property and equipment, net consist of the following (in thousands):

	December 31,
	2017			2016
Lab equipment	$	36		$	35
Computer equipment and software		150			107
Total property and equipment		186			142
Less: accumulated depreciation		(107	)		(66	)
Property and equipment, net	$	79		$	76

Depreciation expense for the years ended December 31, 2017, 2016 and 2015 was $41,000, $23,000 and $11,000, respectively.

Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	December 31,
	2017		2016
Compensation and related benefits	$	1,262	$	1,299
Contract research costs		634		834
Consulting costs		87		106
Franchise tax		56		97
Contract manufacturing costs		4		122
Other		41		191
Total accrued liabilities	$	2,084	$	2,649

Reverse Merger

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Reverse Merger

5.	Reverse Merger

On March 22, 2016, Eiger completed the Merger with Celladon as discussed in Note 1. For accounting purposes, Eiger is considered to have acquired Celladon in the Merger. Eiger was determined to be the accounting acquirer based upon the terms of the Merger and other factors including; (i) Eiger security holders owned approximately 78% of the combined company immediately following the closing of the Merger, (ii) Eiger directors held all of the board seats in the combined company, and (iii) Eiger management held all key positions in the management of the combined company. The Merger was accounted for as an asset acquisition rather than business combination because the assets acquired and liabilities assumed by Eiger did not meet the definition of a business as defined by U.S. GAAP. The net assets acquired in connection with this transaction were recorded at their estimated acquisition date fair values as of March 22, 2016, the date the Merger with Celladon was completed.

Immediately prior to the effective date of the Merger and in connection with the Private Placement, the Notes converted into shares of common stock of Eiger. Further, all of the Warrants were exercised for common stock (see Note 9) and all shares of preferred stock of Eiger converted into shares of common stock of Eiger.

At the effective date of the Merger, Celladon issued shares of its common stock to Eiger stockholders, at an exchange rate of approximately 0.09 shares of common stock, after taking into account the Reverse Stock Split, in exchange for each share of Eiger common stock outstanding immediately prior to the Merger. The exchange rate was calculated by a formula that was determined through arms-length negotiations between Celladon and Eiger. The combined Company assumed all of the outstanding options, whether or not vested, under the Eiger 2009 Equity Incentive Plan (the “Eiger Plan”) with such options henceforth representing the right to purchase a number of shares of Celladon common stock equal to approximately 0.09 multiplied by the number of shares of Eiger common stock previously represented by such options.

Immediately after the Reverse Stock Split and the Merger on March 22, 2016, there were 6,945,401 shares of the combined Company’s common stock outstanding. In addition, immediately after the Merger, pre-Merger Eiger stockholders, warrant holders and option holders owned approximately 78% of the aggregate number of shares of the combined Company’s common stock, and the stockholders of Celladon immediately prior to the Merger owned approximately 22% of the aggregate number of shares of the combined Company’s common stock (on a fully diluted basis).

On March 22, 2016, Celladon had 1,596,959 shares of common stock outstanding and a market capitalization of $27.5 million. The estimated fair value of the net assets of Celladon on March 22, 2016 was $27.3 million. The fair value of Celladon’s common stock on the Merger closing date was above the fair value of Celladon’s net assets. As Celladon’s net assets were predominantly comprised of cash offset by current liabilities, the fair value of Celladon’s net assets as of March 22, 2016 was considered to be the best indicator of the fair value and, therefore, the estimated purchase consideration.

The following table summarizes the net assets acquired based on their estimated fair values as of March 22, 2016 (in thousands):

Cash and cash equivalents	$	28,018
Prepaid and other assets		198
Current liabilities		(857	)
Non-current liabilities		(12	)
Net acquired tangible assets		27,347
Estimated total purchase consideration	$	27,347

License Agreements

12 Months Ended

Dec. 31, 2017

License Agreements [Abstract]

License Agreements

6.	License Agreements

Bristol-Meyers Squibb License Agreement

On April 20, 2016, the Company and Bristol-Myers Squibb Company (“BMS”) entered into a License Agreement (the “BMS License Agreement”) and a Common Stock Purchase Agreement (the “BMS Purchase Agreement”).

Under the BMS License Agreement, BMS granted the Company an exclusive, worldwide, license to research, develop, manufacture, and sell products containing the proprietary BMS molecule known as PEG-interferon Lambda-1a (the “Licensed Product”) for all therapeutic and diagnostic uses in humans and animals. The Company is responsible for the development and commercialization of the Licensed Product at its sole cost and expense. The License Agreement required the Company to make an upfront payment of $2.0 million in cash and issue $3.0 million in Company common stock (see below) and includes development and regulatory milestone payments totaling $61.0 million and commercial sales milestones of up to $128.0 million. The Company is obligated to pay BMS annual net sales royalties in the range of mid-single to mid-teens, depending on net sales levels. In addition, if the Company grants a sublicense, the Company is obligated to pay BMS a portion of the sublicensing income received.

The Company paid BMS an upfront payment of $2.0 million in cash in April 2016, which was charged to research and development expense in the consolidated statement of operations as there is no future alternative use for the intellectual property licensed.

The Company issued BMS $3.0 million in common stock as an element of the upfront payment. The BMS Purchase Agreement provided for the issuance of 157,587 shares of common stock of the Company to BMS in consideration of the license granted to the Company under the BMS License Agreement. The BMS Purchase Agreement grants BMS certain registration rights with respect to the shares of common stock delivered, and BMS has agreed to certain trading and other restrictions with respect to the shares issued. In April 2016, the Company issued 157,587 common shares to BMS for an aggregate fair value of $3.2 million, which was charged to research and development expense in the consolidated statement of operations as there is no future alternative use for the intellectual property licensed.

Merck License Agreement

In September 2010, the Company entered into an exclusive license agreement with Schering Corporation, subsequently acquired by Merck & Co., Inc. (“Merck”), which provides the Company with the exclusive right to develop, manufacture, and sell products containing the compounds lonafarnib for the treatment of all human viruses except certain specified viruses such as hepatitis B and hepatitis C alone. As consideration for such exclusive right, the Company issued Private Eiger convertible preferred stock with a fair value of $0.5 million when the agreement was executed in September 2010. This preferred stock was converted to 27,350 shares of common stock upon the Merger. In addition, the Company is obligated to pay Merck up to an aggregate of $27.0 million in development milestones and will be required to pay tiered royalties based on aggregate annual net sales of all licensed products ranging from mid-single to low double-digit royalties on net sales. The Company’s obligation to pay royalties to Merck expires on a country-by-country and product-by-product basis on the later of the expiration of the last to expire patent assigned to the Company under the agreement, which is estimated to be in the first half of 2018; or on the tenth anniversary of the first commercial sale of the product. In May 2015, the first regulatory milestone was achieved and the Company paid the related milestone payment of $1.0 million to Merck. The amount has been recorded as a charge to research and development expense during the year ended December 31, 2015. No additional milestones have been achieved during the years ended December 31, 2017 and 2016.

Janssen License Agreement

In December 2014, the Company entered into a license agreement with Janssen Pharmaceutica NV, (“Janssen”), which provides to the Company with the exclusive worldwide license to develop, manufacture, and sell products containing the compound tipifarnib for all therapeutic and diagnostic uses in humans, including any such uses for human virology diseases, but excluding oncology diseases. The Company is responsible for the development of at least one product in a major market country and for commercialization of products in all countries where necessary authorization is obtained, at its sole cost and expense. The Company may manufacture, develop, and commercialize the products itself or grant one or more sublicenses for such purposes. However, for a period of time following completion of the proof of concept trial, Janssen has a first right of negotiation for an exclusive license back from the Company to develop and commercialize tipifarnib in any country in the world. The agreement will continue for so long as the Company owe royalty payments to Janssen under the agreement or for so long as there is a valid patent claim under the agreement, whichever is longer.

In connection with this license agreement, the Company is obligated to make development milestone payments in aggregate of up to $38.0 million, sales milestone payments in aggregate up to $65.8 million and will be required to pay tiered royalties based on aggregate annual net sales of all licensed products ranging from mid-single to low double-digit royalties of net sales. As of December 31, 2017, the product has not reached commercialization and no milestones have been paid.

Asset Purchase Agreements and Related License Agreements

12 Months Ended

Dec. 31, 2017

Asset Purchase Agreements And Related License Agreements [Abstract]

Asset Purchase Agreements and Related License Agreements

7.	Asset Purchase Agreements and Related License Agreements

EGI Asset Purchase Agreement

In December 2010, the Company entered into an asset purchase agreement with Eiger Group International, Inc. (“EGI”). Dr. Jeffrey Glenn, a founder and director of the Company, is the sole owner of EGI. Pursuant to the agreement, the Company purchased all of the assets including the intellectual property rights related to the use of farnesyl transferase inhibitors as anti-viral agents and methods to treat viral infections with those inhibitors and inhibitors of prenylation, prenyl cysteine methyltranferase and a protease as anti-viral agents and methods to treat viral infection with those inhibitors. The Company paid EGI an upfront payment of $0.4 million when the agreement was executed in December 2010. Additionally, the Company will pay EGI a low single-digit royalty based on aggregate annual net sales of products developed using the intellectual property. Within the first ten years after commercialization, the Company may make a one-time payment of $0.5 million for each contract for the three types of product related to such intellectual property that would reduce the payment term for the three products to the tenth anniversary of the first commercial sale. The obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either when the product is no longer sold in any country or the earliest of the tenth anniversary of the first commercial sale of the product. As of December 31, 2017, the product has not achieved regulatory approval.

In November 2012, the Company entered into an agreement with EGI whereby the Company sold all of the assets related to the compound clemizole, including any related intellectual property. EGI will pay to the Company a high single-digit royalty on future aggregate annual net sales, subject to certain reductions and exceptions. EGI’s obligation to pay royalties expires on a country-by-country and product-by-product basis on the later of either expiration of the last to expire patent sold to EGI under the agreement or the earliest of the tenth anniversary of the first commercial sale of the product. As of December 31, 2017, the product has not achieved regulatory approval.

Exendin 9-39 Purchase Agreement and Related Stanford License Agreement

In September 2015, the Company entered into an asset purchase agreement with two individuals, Dr. Tracey McLaughlin and Dr. Colleen Craig, (the “Sellers”), whereby the Company purchased all of the assets related to the compound exendin 9-39 including any related intellectual property from the Sellers (the “Exendin APA”). The Company also entered into a consulting agreement with the Sellers as part of the agreement. The Company issued 15,378 shares of common stock that were valued at $0.2 million and options to purchase 46,134 shares of common stock with an exercise price of $2.06 per share when the agreement was executed in September 2015.

Of the 46,134 options to purchase common stock, 15,378 shares vest monthly over four years as services are provided by the Sellers and 30,756 vest upon the earlier of the first commercial sale of the product or the approval of new drug application by the U.S. Food and Drug Administration (the milestone-vested options).

On March 22, 2016, immediately following the closing of the Merger, the Company issued additional “top-up” options to Dr. Tracey McLaughlin and Dr. Colleen Craig to purchase an aggregate of 48,544 shares of common stock, pursuant to the terms of the Exendin APA, with an exercise price of $17.25 per share. The top-up options consist of both time-vested and milestone-vested options.

The fair value of the time-vested options is recognized as non-employee share-based compensation expense as the awards vest over time, with the unvested portion revalued each period. The fair value of the milestone-vested options will be recognized as research and development expense when it is probable that the earliest milestone will be achieved at their then fair value. During the years ended December 31, 2017, 2016 and 2015, the Company recognized $44,000, $0.3 million and $15,000 of non-employee compensation expense related to the time-vested options, respectively. No expense was recognized for the milestone vested options during the years ended December 31, 2017, 2016 and 2015.

The Company is also obligated to pay development milestone payments in an aggregate amount of up to $1.0 million to each Seller. Additionally, the Company is obligated to pay each Seller royalties of low single-digits based on aggregate annual net sales of all products developed based on exendin 9-39, subject to certain reductions and exceptions. The Company’s obligation to pay royalties expires on the expiration of the last to expire patent assigned to the Company under the agreement. Additionally, the Company has assumed the license agreement the Sellers had previously entered into with the Board of Trustees of the Leland Stanford Junior University (“Stanford”). The Company is obligated to pay a royalty to Stanford in the low single-digits on annual net sales after the first commercial sale of any products developed based on exendin 9-39. As of December 31, 2017, upon the successful completion of the Phase 2 trials, the development milestone was achieved and the Company paid the related milestone payment of $0.1 million to each of the Sellers.

Eiccose Purchase Agreement and Related Stanford and Nippon License Agreements

In October 2015, the Company entered into an asset purchase agreement with Eiccose whereby Eiccose sold all of the assets related to the treatment of pulmonary arterial hypertension (“PAH”), treatment of lymphedema and products containing ubenimex for the treatment of disorders involving LTB4, and any related intellectual property to the Company (the “Eiccose APA”). David Cory, the President, Chief Executive Officer and a director of the Company, is the sole managing member and significant equity interest holder of Eiccose. The Company made a payment to Eiccose of $0.1 million representing reimbursement of certain previously incurred expenses, including payments and accrued amounts owed to Stanford in connection with the license agreement for the treatment of Lymphedema (the “Lymphedema License Agreement”) and the license agreement for the treatment of PAH (the “PAH License Agreement”). The Eiccose APA also provided that, upon a next round of financing pursuant to which the Company sold shares of capital stock resulting in gross proceeds to the Company of at least $25.0 million, the Company would issue to Eiccose fully vested shares of the Company’s common stock equal to 1.75% of the total number of the Company’s outstanding capital stock, before Merger. In October 2015, the Company recorded $1.5 million in research and development expenses and a corresponding liability representing the fair value of the Company’s obligation to issue common stock to Eiccose.

On March 22, 2016, the Company issued to Eiccose 96,300 fully vested shares of the Company’s common stock pursuant to the terms of the Eiccose APA. In connection with this transaction the Company remeasured the fair value of the obligation to issue common stock at the settlement date and the change in fair value of $0.2 million was recognized within other income (expense), net in the consolidated statement of operations during the year ended December 31, 2016. Upon the settlement of the obligation with the issuance of shares on March 22, 2016, the liability was reclassified to common stock and additional paid-in capital within stockholders’ equity (deficit).

The Company is also obligated to pay to Eiccose an aggregate of up to a maximum of $10.0 million of commercial milestones in connection with future sales of the product and royalties in the low single-digits based on aggregate annual net sales following the first commercial sale of any product. As of December 31, 2017, the product has not reached commercialization and no milestones have been paid. In June 2017, Eiccose was disbanded. The Company’s commercial milestone obligations and sales royalties remain, however have been transferred to the previous shareholders of Eiccose.

In addition, as a result of this agreement, the Company has assumed the license agreements Eiccose had previously entered into. These include the PAH License Agreement, the Lymphedema License Agreement for the treatment of lymphedema and the license agreement with Nippon Kayaku Co., Ltd, (“Nippon”). As part of the agreement, Nippon is obligated to make a payment for royalties in the low single-digits of sales to the Company. In connection with the PAH License Agreement and the Lymphedema License Agreement, the Company is obligated to make development and commercial milestone payments of up to $0.5 million in the aggregate under each contract, increasing annual license maintenance fees ranging from $10,000 to $75,000 over the term of each license agreement and royalty payments in low single-digits on annual net sales after the first commercial sale of a product under each license. For the year ended December 31, 2015, the Company recorded $0.2 million to research and development expense including $0.1 million for license fees and $0.1 million for the reimbursement of incurred expenses in connection with the Eiccose APA. For the years ended December 31, 2017 and 2016, no amounts have been recorded in connection with the Eiccose APA.

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

In December 2016, the Company entered into an aggregate $25.0 million loan with Oxford Finance LLC (the “Oxford Loan”). The loan matures on July 1, 2021. The Company borrowed $15.0 million in December 2016 (“Tranche A”). The remaining $10.0 million (“Tranche B”) will be available to the Company upon achievement of positive top line data from the lonafarnib Phase 2 trial in HDV, which was achieved in the fourth quarter of 2016, plus positive top line Phase 2 data from at least one of the following programs: (i) Lambda in HDV, (ii) Exendin 9-39 in PBH based on the Company’s own IND, (iii) ubenimex in PAH, or (iv) ubenimex in Lymphedema.

The Oxford Loan bears interest at a floating rate per annum equal to the greater of either the 30-day U.S. Dollar LIBOR reported in the Wall Street Journal plus 6.41% or 6.95%. The Company is required to repay the Tranche A in 18 monthly interest only payments followed by 36 equal monthly payments of principal and interest commencing on the first day of the month following the funding of Tranche A. If the Company receives the Tranche B funds, then the interest only period is extended by six months followed by 30 equal monthly payments of principal plus accrued interest. At the time of final payment, the Company is required to pay an exit fee of 7.5% of the original principal balance of each tranche, which will be $1.1 million for Tranche A. The Company recorded as a liability and debt discount the exit fee at the origination of the term loan. In addition, the Company incurred loan origination fees and debt issuance costs of $0.3 million which were recorded as a direct deduction from the carrying amount of the related debt liability as a debt discount. The Company is also required to pay a 5.0% success fee within 30 days following the FDA’s approval of the Company’s first product. This fee is enforceable within 10 years from the funding of Tranche A. In connection with the execution of the Loan Agreement, the Company agreed to certain customary representations and warranties.

The loan is secured by the perfected first priority liens on the Company's assets, including a commitment by the Company to not allow any liens to be placed upon the Company’s intellectual property. The Oxford Loan includes customary events of default, including failure to pay amounts due, breaches of covenants and warranties, material adverse effect events, certain cross defaults and judgments, and insolvency. If the Company is unable to comply with these covenants or if the Company defaults on any portion of the outstanding borrowings, the lenders can also impose a 5.0% penalty and restrict access to additional borrowings under the loan and security agreement. The Company was in compliance with the terms under the Oxford Loan as of December 31, 2017 and 2016.

The Company is permitted to make voluntary prepayments of the Oxford Loan with a prepayment fee, calculated as of the loan origination date, equal to (i) 3.0% of the loan prepaid during the first 12 months, (ii) 2.0% of the loan prepaid in months 13-24 and (iii) 1.0% of the loan prepaid thereafter. The Company is required to make mandatory prepayments of the outstanding loan upon the acceleration by lender following the occurrence of an event of default, along with a payment of the final payment, the prepayment fee and any other obligations that are due and payable at the time of prepayment.

The Company accounts for the amortization of the debt discount utilizing the effective interest method. The Company recorded interest expense of $1.1 million and $5,000 for the years ended December 31, 2017 and 2016, respectively. Long-term debt and unamortized discount balances are as follows (in thousands):

	December 31,
	2017			2016
Face value of long term debt	$	15,000		$	15,000
Exit fee		1,125			1,125
Unamortized debt discount associated with exit fee, debt issuance costs and loan origination fees		(1,032	)		(1,398	)
Total long term debt		15,093			14,727
Less: current portion of long term debt		(2,002	)		—
Long term debt, net	$	13,091		$	14,727

As of December 31, 2017, future minimum payments of principal, exit fee and interest expense under the Oxford Loan were as follows (in thousands):

Year ending December 31,
2018	$	3,239
2019		5,839
2020		5,445
2021		4,118
Total future payments		18,641
Less: unamortized interest		(2,516	)
Less: exit fee		(1,125	)
Face value of term loan	$	15,000

Convertible Promissory Note and Warrant Purchase Agreement

12 Months Ended

Dec. 31, 2017

Disclosure Of Convertible Promissory Note And Warrant Purchase Agreement [Abstract]

Convertible Promissory Note and Warrant Purchase Agreement

9.	Convertible Promissory Note and Warrant Purchase Agreement

On November 12, 2015, the Company entered into a convertible note and warrant purchase agreement (the “Note and Warrant Purchase Agreement”) with three lenders under which the Company issued the Notes for an aggregate principal amount of $6.0 million and the Warrants exercisable for shares of the Company’s equity securities at a purchase price of $0.11 per share, on a post-Merger and post-Reverse Stock Split basis. The terms of the Notes included a provision whereby the Notes would be automatically converted into equity securities from a qualified financing with proceeds of at least $25.0 million. The terms of the Warrants included a provision whereby the Warrants would be automatically exercised if the Company consummated a public offering including a reverse merger (“PO”). If the PO did not occur on or prior to February 28, 2016, the warrant coverage amount was equal to 17.5% of the outstanding principal balance of the Notes. The number of warrant shares into which the Warrants could be exercised was equal to the warrant coverage amount divided by the per share price of the equity securities sold in a qualified financing for an exercise price of $0.11 per share, on a post-Merger and post-Reverse Stock Split basis. The Warrants also include a provision whereby in the event of a PO which would result in the automatic exercise of the Warrants and the automatic conversion of the Notes, the exercise price of the warrants would be paid by cancelling any unpaid interest on the Notes.

On November 18, 2015, the Company entered into the Subscription Agreement with the holders of the Notes and new investors for the sale of 2,304,430 shares of its common stock at purchase price of $17.14 per share for total gross proceeds of $39.5 million. The proceeds were comprised of approximately $6.0 million from the conversion of the Notes and approximately $33.5 million of cash.

The Company allocated the aggregate proceeds from the issuance of the Notes first to the Warrants based on the warrants’ fair value and then the residual proceeds were allocated to the debt obligation. As of December 31, 2015, the fair value of warrants of $0.9 million was recorded as a debt discount to be amortized as interest expense over the term of the Note using the effective interest rate method. The fair value of the Warrants was also recorded as a corresponding warrant liability.

In addition, the Company incurred debt issuance costs of $21,000 in connection with the Note and Warrant Purchase Agreement. The debt issuance costs were being amortized to interest expense over the term of the Note using the effective interest rate method.

Upon the closing of the Private Placement on March 22, 2016, immediately prior to the closing of the Merger, the outstanding balance of the Notes totaling approximately $6.0 million was converted into 350,040 shares of the Company’s common stock. The Warrants were exercised for 61,254 shares of the Company’s common stock. During the year ended December 31, 2016, the Company recognized a loss related to the change in fair value of the Warrants of $0.2 million. The warrant liability was reclassified to common stock and additional paid-in capital within stockholders’ equity (deficit), upon the exercise of the Warrants and issuance of shares on March 22, 2016.

For the year ended December 31, 2016, the Company recognized $0.7 million related to the accrued interest and amortization of the debt discount within interest expense on the Company’s consolidated statements of operations. The discount was fully amortized upon the conversion of the Notes.

Sale of Assets

12 Months Ended

Dec. 31, 2017

Discontinued Operations And Disposal Groups [Abstract]

Sale of Assets

10.	Sale of Assets

In May 2017, the Company and Theragene Pharmaceuticals, Inc. (“Theragene”) entered into an asset purchase agreement (“Theragene APA”), whereby the Company sold all of the assets related to MYDICAR including any related intellectual property for a cash payment of $0.2 million and 475,000 shares of common stock of Theragene. At any time after the Theragene APA execution date and until Theragene has received cumulative gross proceeds of $4.0 million (“Proceeds Date”) from all equity financing transactions occurring after the Theragene APA execution date, if Theragene issues additional shares of its common stock without consideration or for a consideration per share less than $6.00 per share then Theragene will issue additional shares of its common stock to the Company concurrently with such issue, in an amount such that the per share consideration multiplied by the aggregate number of common stock shares issued to the Company will equal $2.85 million. Additionally, the Company may exercise a put option at any time after the Proceeds Date, where upon written notice from the Company, Theragene will repurchase the 225,000 shares of its common stock held by the Company (“Option Shares”) at an aggregate purchase price equal to the greater of $1.35 million or the aggregate fair market value of the Option Shares as of the date of the receipt notice. The Company is also eligible to receive contingent consideration up to a maximum $45.0 million in cash, based upon Theragene achieving certain specified future milestones. In addition, the Company is also eligible to receive up to 8% royalties on net sales of any future Theragene products covered by or involving the related patents or know-how until the 20^th anniversary of the Theragene APA.

The Company has determined that the sale of the MYDICAR assets qualify as an asset sale and not a business.

During the year ended December 31, 2017, the Company received a cash payment of $0.2 million, which was recognized as other income (expense), net in the consolidated statement of operations. Concurrently with the execution of the Theragene APA, the Company became an owner of 475,000 shares of common stock of Theragene and a put option for 225,000 shares of common stock of Theragene, which were recognized as a cost method investment with carrying value of zero. As of December 31, 2017, there was no change in the fair value of our equity investment in Theragene.

Stockholders' Equity

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Stockholders' Equity

11.	Stockholders’ Equity

Common Stock

The holders of the Company’s common stock have one vote for each share of common stock. Common stockholders are entitled to dividends when, as, and if declared by the Board of Directors, subject to the prior rights of the convertible preferred stockholders. As of December 31, 2017, no dividends had been declared by the Board of Directors.

The Company had reserved shares of common stock for issuance as follows:

	December 31,
	2017		2016
Options issued and outstanding		1,467,051		1,212,044
Options available for future grants		799,375		646,778
Warrants to purchase common stock issued and outstanding		10,180		10,180
Total		2,276,606		1,869,002

Warrants

The Company issued the Warrants in connection with the issuance of the Notes (see Note 9). As of December 31, 2015, the Company accounted for the Warrants as a liability at fair value as the number of shares were not fixed and determinable at the issuance date. The Company adjusted the liability for changes in fair value until the exercise of the Warrants in March 2016, when the number of shares to be exercised became fixed, and the Warrants were automatically exercised into common stock. The warrant liability was immediately reclassified to common stock and additional paid in capital within stockholders’ equity (deficit). The change in fair value of the warrant liability was recognized as a component of other income (expense), net in the consolidated statements of operations.

The Company assumed from Celladon fully exercisable warrants outstanding for the purchase of 10,180 shares of common stock. The warrants have an exercise price of $84.15 per share and expire in October 2018.

Stock Option Plan

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Plan

12.	Stock Option Plan

In 2009, the Company adopted the 2009 Equity Incentive Plan or the Plan. Under the Plan, shares of the Company’s common stock have been reserved for the issuance of stock options to employees, directors, and consultants under terms and provisions established by the Board of Directors. Under the terms of the Plan, options may be granted at an exercise price not less than fair market value. For employees holding more than 10% of the voting rights of all classes of stock, the exercise prices for incentive and non-statutory stock options may not be less than 110% of fair market value, as determined by the Board of Directors. The terms of options granted under the Plan may not exceed ten years. The vesting schedule of newly issued option grants is generally four years.

As discussed in Note 5, the Company assumed all of the outstanding options, whether or not vested, under the Eiger Plan, with such options henceforth representing the right to purchase a number of shares of the Company’s common stock equal to approximately 0.09 multiplied by the number of shares of Eiger common stock previously represented by such options. For accounting purposes, however, the Company is deemed to have assumed the Celladon 2013 Equity Incentive Plan.

Because the Company is considered to be the acquirer for accounting purposes, the pre-Merger vested stock options granted by Celladon are deemed to have been exchanged for equity awards of the Company and, as such, the portion of the acquisition date fair value of these equity awards attributable to pre-Merger service to Celladon were accounted for as a component of the consideration transferred, which was inconsequential to the consolidated financial statements.

The exchange of options to purchase shares of Eiger common stock for options to purchase shares of the Combined Company, was accounted for as a modification of the awards because the legal exchange of the awards is considered a modification of Eiger stock options. The modification of the stock options did not result in any incremental compensation expense as the modification did not increase the fair value of the stock options.

In June 2016, the Company’s board of directors adopted and in August 2016 the Company’s stockholders approved the amended and restated 2013 Equity Incentive Plan (the “Restated 2013 Plan”), which increased the number of shares reserved for grant by 1,296,683 shares. Under the terms of the Restated 2013 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then employees, officers, non-employee directors or consultants of the Company. All awards granted prior to the approval of the Restated 2013 Plan remain subject to the terms of the previous plans and the applicable award agreements. The following table summarizes stock option activity under the Company’s stock-based compensation plan during the years ended December 31, 2017 and 2016 (in thousands, except share and per share data):

	Shares Available for Grant			Number of Options			Weighted- Average Exercise Price Per Option		Weighted- Average Remaining Contractual Life (in Years)		Aggregate Intrinsic Value
Outstanding as of December 31, 2016		646,778			1,212,044		$	14.06		9.00	$	2,414
Additional options authorized		417,833			—			—
Granted		(652,200	)		652,200		$	10.91
Exercised		—			(10,229	)	$	5.04
Forfeited or cancelled		386,964			(386,964	)	$	14.13
Outstanding as of December 31, 2017		799,375			1,467,051		$	12.70		8.41	$	4,511
Vested and exercisable as of December 31, 2017					630,727		$	13.82		8.01	$	2,117

The aggregate intrinsic values of options outstanding, exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the closing price of the Company’s common stock of $13.95 as of December 31, 2017.

The aggregate intrinsic value of stock options exercised in 2017, 2016 and 2015 was $0.1 million, $0.1 million and $0.9 million, respectively.

Stock Options Granted to Employees

During the years ended December 31, 2017, 2016 and 2015, the Company granted employees stock options for the purchase of 579,700, 902,028 and 166,793 shares, respectively, with a weighted-average grant date fair value of $7.66, $10.40 and $1.09 per share, respectively. The total grant date fair value of employee options that vested during the years ended December 31, 2017, 2016 and 2015 was $5.0 million, $2.0 million and $6,000, respectively.

The Company records stock-based compensation of stock options granted to employees by estimating the fair value of stock-based awards using the Black-Scholes option pricing model and amortizing the fair value of the stock-based awards granted over the applicable vesting period of the awards on a straight-line basis. The fair value of employee stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31,
	2017		2016		2015
Expected term (in years)	5.27 - 6.08		5.27 - 6.08		5.00 - 6.08
Volatility	79.00% - 80.00%		73.91% - 78.00%		77.58% - 97.62%
Risk free interest rate	1.63% - 2.23%		1.21% - 2.27%		1.44% - 1.75%
Dividend yield		—		—		—

Each of these inputs is subjective and generally requires judgment to determine.

Fair Value of Common Stock: Prior to the Merger, the fair value of the shares of common stock underlying stock options was determined by the Company’s Board of Directors. In order to determine the fair value of the common stock at the time of grant of the option, the Board of Directors considered, among other things, valuations performed by an independent third-party. Because there was no public market for the Company’s common stock, the Board of Directors exercised reasonable judgment and considered a number of objective and subjective factors to determine the best estimate of the fair value of the Company’s common stock, including important developments in the Company’s operations, sales of convertible preferred stock, actual operating results and financial performance, the conditions in the life sciences industry and the economy in general, the stock price performance and volatility of comparable public companies, and the lack of liquidity of the Company’s common stock, among other factors. Following the Merger, the Company’s Board of Directors determined the fair value of each share of underlying common stock based on the closing price of the Company’s common stock as reported on the date of grant.

Expected Term: The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term for employee options).

Expected Volatility: Since the Company does not have a long trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, or stage in the life cycle.

Risk-Free Interest Rate: The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option.

Expected Dividend: The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Stock Options Granted to Non-Employees

The Company grants stock options to non-employees in exchange for services rendered. During the years ended December 31, 2017, 2016 and 2015, the Company granted to non-employees stock options for 72,500, 48,544 and 46,134 shares, respectively. Stock-based compensation expense related to stock options granted to non-employees is recognized as the stock options are earned and will fluctuate as the estimated fair value of the common stock fluctuates until the awards vest. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services rendered.

The fair value of the stock options granted to non-employees is estimated at each reporting date using the Black-Scholes option-pricing model using similar assumptions as for employees except that the expected term is based on the options’ remaining contractual term instead of the simplified method:

Year Ended December 31,

2017

2016

2015

Remaining contractual term (in years)

6.00 – 10.00

6.75 – 10.00

7.75 – 10.00

Volatility

83.62% – 106.13%

84.42% – 98.13%

85.83% – 90.50%

Risk-free interest rate

1.90% – 2.43%

1.37% – 2.50%

1.73% – 2.24%

Dividend yield

—

Stock-Based Compensation Expense

Total stock-based compensation expense recognized for options granted to employees and non-employees was as follows (in thousands):

	Year Ended December 31,
	2017		2016		2015
Research and development	$	1,214	$	737	$	64
General and administrative		3,029		2,453		163
Total stock-based compensation expense	$	4,243	$	3,190	$	227

As of December 31, 2017, the total unrecognized compensation expense related to unvested employee options was $6.8 million, which the Company expects to recognize over an estimated weighted average period of 2.7 years.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

13.	Income Taxes

No provision for income taxes was recorded for the years ended December 31, 2017, 2016 and 2015. The Company has incurred net operating losses for all the periods presented. The Company has not reflected any benefit of such net operating loss carryforwards in the accompanying consolidated financial statements. The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding the realization of such assets.

The effective tax rate of the provision for income taxes differs from the federal statutory rate as follows:

	Year Ended December 31,
	2017			2016			2015
Federal statutory income tax rate		34.00	%		34.00	%		34.00	%
State income taxes, net of federal benefit		0.36			(0.21	)		6.11
Federal and state tax credits		5.10			4.68			2.54
Change in valuation allowance		(8.04	)		(36.67	)		(42.14	)
Stock-based compensation		(1.06	)		(1.26	)		(0.49	)
Other, net		—			(0.54	)		(0.02	)
Change in tax law		(30.36	)		—			—
Provision (benefit) for income taxes