Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2014	Mar. 16, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	CERU
Entity Registrant Name	CERULEAN PHARMA INC.
Entity Central Index Key	0001401914
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	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		20,375,987
Entity Public Float			$ 74,209,799.40

Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 51,174	$ 5,488
Accounts receivable, prepaid expenses, and other current assets	1,662	959
Total current assets	52,836	6,447
Property and equipment — Net	342	245
Other assets	215	135
Total	53,393	6,827
Current liabilities:
Current portion of loan payable	3,124	3,134
Convertible promissory notes payable to shareholders		8,824
Accounts payable	1,255	914
Accrued expenses	3,648	2,274
Other liabilities	34
Total current liabilities	8,061	15,146
Long-term liabilities:
Loan payable — net of current portion		3,124
Preferred stock warrant liability		928
Noncurrent accrued interest		391
Other	7	12
Total long-term liabilities	7	4,455
Redeemable convertible preferred stock (Note 8)		81,525
Commitments (Note 13)
Stockholders’ equity (deficit):
Preferred stock, $0.01 par value; 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock, $0.0001 par value; 120,000,000 shares authorized, 20,125,049 and 785,531 shares issued and outstanding at December 31, 2014 and 2013, respectively	2
Additional paid-in capital	167,104	4,140
Accumulated deficit	(121,781)	(98,439)
Total stockholders’ equity (deficit)	45,325	(94,299)
Total	$ 53,393	$ 6,827

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	20,125,049	785,531
Common stock, shares outstanding	20,125,049	785,531

Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended								12 Months Ended
	Apr. 30, 2014	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Revenue				$ 33	$ 47	$ 6				$ 80	$ 6	$ 625
Operating expenses:
Research and development		4,701	2,928	2,648	1,495	1,440	1,586	3,195	3,479	11,772	9,700	15,807
General and administrative		2,607	2,441	2,029	1,510	1,575	1,227	1,392	1,972	8,587	6,166	6,393
Total operating expenses		7,308	5,369	4,677	3,005	3,015	2,813	4,587	5,451	20,359	15,866	22,200
Other income (expense):
Interest income		4	2	2	1	1			1	9	2	2
Interest expense		(163)	(191)	(268)	(461)	(430)	(378)	(326)	(353)	(1,083)	(1,487)	(567)
Loss on extinguishment of debt	(2,493)			(2,493)						(2,493)
Decrease in value of preferred stock warrant liability					504	(42)	(7)	20	231	504	202	39
Total other income (expense) — net		(159)	(189)	(2,759)	44	(471)	(385)	(306)	(121)	(3,063)	(1,283)	(526)
Net loss										(23,342)	(17,143)	(22,101)
Accretion of redeemable convertible preferred stock												(73)
Net loss attributable to common stockholders		$ (7,467)	$ (5,558)	$ (7,403)	$ (2,914)	$ (3,480)	$ (3,198)	$ (4,893)	$ (5,572)	$ (23,342)	$ (17,143)	$ (22,174)
Net loss per share attributable to common stockholders:
Basic and diluted		$ (0.37)	$ (0.28)	$ (0.44)	$ (3.70)	$ (4.45)	$ (4.40)	$ (7.96)	$ (9.09)	$ (1.60)	$ (25.05)	$ (36.39)
Weighted-average common shares outstanding:
Basic and diluted		20,125,009	20,124,574	16,883,716	786,986	782,335	726,987	614,662	612,836	14,548,516	684,330	609,344

Consolidated Statement of Redeemable Preferred Stock and Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data	Total USD ($)	Series D Convertible Preferred Stock [Member] USD ($)	IPO [Member] USD ($)	Redeemable Convertible Preferred Stock [Member] USD ($)	Redeemable Convertible Preferred Stock [Member] Series D Convertible Preferred Stock [Member] USD ($)	Common Stock [Member] USD ($)	Common Stock [Member] IPO [Member]	Additional Paid-in Capital [Member] USD ($)	Additional Paid-in Capital [Member] IPO [Member] USD ($)	Accumulated Deficit [Member] USD ($)
Redeemable convertible preferred stock, Beginning balance at Dec. 31, 2011				$ 70,751
Beginning balance at Dec. 31, 2011	(58,397)							798		(59,195)
Redeemable convertible preferred stock, Beginning balance, shares at Dec. 31, 2011				71,374,896
Beginning balance, shares at Dec. 31, 2011						609,041
Exercise of stock options	3							3
Exercise of stock options, shares						904
Sale of convertible preferred stock					12,927
Sale of convertible preferred stock, shares					15,662,650
Stock-based compensation	529							529
Accretion of issuance costs to redemption value	(73)			73				(73)
Net loss	(22,101)									(22,101)
Redeemable convertible preferred stock, Ending balance at Dec. 31, 2012				83,751
Ending balance at Dec. 31, 2012	(80,039)							1,257		(81,296)
Redeemable convertible preferred stock, Ending balance, shares at Dec. 31, 2012				87,037,546
Ending balance, shares at Dec. 31, 2012						609,945
Exercise of stock options	35							35
Exercise of stock options, shares						8,911
Stock-based compensation	622							622
Conversion of convertible preferred stock into common stock	2,226			(2,226)				2,226
Conversion of convertible preferred stock into common stock, shares				(1,830,190)		166,675
Net loss	(17,143)									(17,143)
Redeemable convertible preferred stock, Ending balance at Dec. 31, 2013	81,525	27,521		81,525
Ending balance at Dec. 31, 2013	(94,299)							4,140		(98,439)
Redeemable convertible preferred stock, Ending balance, shares at Dec. 31, 2013	85,207,356	33,158,272		85,207,356
Ending balance, shares at Dec. 31, 2013						785,531
Exercise of stock options	140							140
Exercise of stock options, shares	41,566					41,566
Stock-based compensation	885							885
Issuance of Common Stock from initial public offering	59,862					1		59,861
Issuance of Common Stock from initial public offering, shares							9,569,715
Conversion of convertible preferred stock into common stock	81,526			(81,525)		1		81,525
Conversion of convertible preferred stock into common stock, shares				(85,207,356)		6,826,004
Reclassification of warrants			424						424
Conversion of convertible notes	20,129							20,129
Conversion of convertible notes, shares						2,902,233
Net loss	(23,342)									(23,342)
Ending balance at Dec. 31, 2014	$ 45,325					$ 2		$ 167,104		$ (121,781)
Ending balance, shares at Dec. 31, 2014						20,125,049

Consolidated Statement of Redeemable Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended				12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014 IPO [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Series D Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.01
Common stock, par value	$ 0.0001
Issuance/sale of stock, price per share					$ 0.83
Stock issuance costs	$ 187	$ 7,126			$ 73
Conversion price, per share			$ 14.51	$ 39.21

- Definition

Amount to be paid per share that is classified as temporary equity by entity upon redemption. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References+ Details

Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net loss	$ (23,342)	$ (17,143)	$ (22,101)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	885	622	529
Noncash rent expense	29	(1)	(68)
Change in carrying value of preferred stock warrant liability	(504)	(202)	(39)
Depreciation and amortization	126	197	346
Loss (gain) on disposal of property and equipment	(28)	7	2
Loss on extinguishment of debt	2,493
Noncash interest expense	416	588	61
Changes in operating assets and liabilities:
Accounts receivable, prepaid expenses and other current assets	(713)	(229)	(61)
Accounts payable	341	14	(163)
Accrued expenses	1,236	(467)	489
Net cash used in operating activities	(19,061)	(16,614)	(21,005)
Cash flows from investing activities:
Purchases of property and equipment	(225)	(7)	(180)
Proceeds from sale of property and equipment	40
Net cash used in investing activities	(185)	(7)	(180)
Cash flows from financing activities:
Proceeds from sale of common stock	140	35	3
Proceeds from issuance of convertible promissory notes	8,500	8,824
Proceeds from initial public offering, net	59,862
Proceeds from loans payable			10,000
Payments on capital lease			(3)
Payments on loans payable	(3,348)	(3,084)	(376)
Cash paid for debt issuance costs	(222)	(373)	(4)
Proceeds from sale of redeemable convertible preferred stock, net of issuance costs			12,927
Net cash provided by financing activities	64,932	5,402	22,547
Net increase (decrease) in cash and cash equivalents	45,686	(11,219)	1,362
Cash and cash equivalents — Beginning of year	5,488	16,707	15,345
Cash and cash equivalents — End of year	51,174	5,488	16,707
Supplemental disclosures of noncash investing and financing activities:
Conversion of redeemable convertible preferred stock into common stock	81,526	2,226
Conversion of convertible notes and accrued interest into common stock, net	20,129
Reclassification of warrants to additional paid-in capital	424
Accretion of redeemable convertible preferred stock to redemption value			73
Fair value of preferred stock warrants issued in connection with debt			360
Supplemental cash flow information — Interest paid	$ 400	$ 664	$ 507

Nature of Business and Operations

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Nature of Business and Operations

1.	NATURE OF BUSINESS AND OPERATIONS

Nature of Business — Cerulean Pharma Inc. (the “Company”) was incorporated on November 28, 2005, as a Delaware corporation and is located in Cambridge, Massachusetts. The Company was formed to develop novel, nanotechnology-based therapeutics in the areas of oncology and other diseases. In 2013, the Company formed a wholly-owned subsidiary, Cerulean Pharma Australia Pty Ltd as an Australian-based proprietary limited company, to perform clinical activities in Australia. To date, operations of the Australia subsidiary have been immaterial.

The Company's operations to date have consisted primarily of raising capital, product research and development, and initial market development. Accordingly, the Company is considered to be in the development stage at December 31, 2014.

The Company has not generated any revenue related to its primary business purpose to date and is subject to a number of risks similar to those of other development stage life science companies, including dependence on key individuals, competition from other companies, the need for development of commercially viable products, and the need to obtain adequate additional financing to fund the development of its product candidates. The Company is also subject to a number of risks similar to other companies in the industry, including rapid technological change, regulatory approval of products, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third parties, product liability and dependence on key individuals.

The Company has an accumulated deficit of $121.8 million at December 31, 2014. The Company has financed its operations primarily through private placements of its preferred stock, proceeds from borrowings, and an initial public offering completed in 2014. The Company has not completed development of any product candidate and has devoted substantially all of its financial resources and efforts to research and development, including preclinical and clinical development. The Company expects to continue to incur significant expenses and increasing operating losses for at least several years.

Initial Public Offering — On April 15, 2014, the Company completed the sale of 8,500,000 shares of its common stock in its initial public offering (the “IPO”), at a price to the public of $7.00 per share. On May 7, 2014, the Company completed the sale of an additional 1,069,715 shares of common stock at a price to the public of $7.00 per share under a partial exercise by the underwriters of their option to purchase additional shares of common stock. The sale of shares to the public resulted in net proceeds of $59.9 million after deducting underwriting discounts and commissions and offering expenses payable by the Company.

In preparation for the IPO, the Company’s board of directors and stockholders approved a 1-for-14.5074 reverse stock split of the Company’s common stock effective March 31, 2014. All share and per share amounts in the consolidated financial statements contained herein and notes thereto have been retroactively adjusted, where necessary, to give effect to this reverse stock split. In connection with the closing of the IPO, all of the Company’s outstanding redeemable convertible preferred stock and convertible notes automatically converted into shares of common stock as of April 15, 2014, resulting in the issuance by the Company of an additional 9,728,237 shares of common stock. The significant increase in shares outstanding in April 2014 is expected to impact the year-over-year comparability of the Company’s net loss per share calculations in future periods.

In connection with the completion of the IPO on April 15, 2014, the Company’s outstanding warrants to purchase 1,857,226 shares of the Company’s preferred stock automatically converted into warrants to purchase an aggregate of 128,663 shares of the Company’s common stock and, as a result, the Company reclassified the warrant liability to additional paid-in capital.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Significant Accounting Policies

2.	SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates — The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period.

On an ongoing basis, the Company's management evaluates its estimates, including estimates related to clinical trial accruals, stock-based compensation expense, and reported amounts of revenues and expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Although the Company regularly assesses these estimates, actual results could differ from those estimates. Changes in estimates are recorded in the period in which they become known.

Principles of Consolidation — The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. All intercompany accounts and transactions have been eliminated.

Segment Information — Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment; however, the Company operates in two geographic regions: United States (Cambridge, MA) and Australia (Sydney, NSW). There is no revenue generated or long-lived assets located within the Australian location.

Cash and Cash Equivalents — Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase and consist primarily of money market funds.

Concentrations of Credit Risk — Financial instruments that subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. Substantially all of the Company’s cash and cash equivalents are held at one financial institution that management believes to be of high-credit quality. Deposits with this financial institution may exceed the amount of insurance provided on such deposits; however these deposits may be redeemed upon demand and, therefore, bear minimal risk.

Restricted Cash — At December 31, 2014 and 2013, the Company has restricted cash of $117,000 representing a letter of credit for the Company’s facility lease that is scheduled to expire in February 2016. The letter of credit is secured by certificates of deposit that renew monthly. The restricted cash is included within other assets in the balance sheet.

Property and Equipment — Property and equipment are recorded at cost and depreciated over their estimated useful lives using the straight-line method. Repairs and maintenance costs are expensed as incurred, whereas major improvements are capitalized as additions to property and equipment.

Depreciation is provided using the straight-line method over the following estimated useful lives:

Laboratory equipment		5 years
Computer equipment		3 years
Office furniture and equipment		5 years
Leasehold improvements		Lesser of useful life or remaining lease term

Impairment of Long-Lived Assets — Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If this comparison indicates that there is impairment, the amount of impairment is calculated as the difference between the carrying value and fair value. For the years ended December 31, 2014 and 2013, the Company has not recorded an impairment charge for its long-lived assets.

Revenue Recognition — The Company’s revenue to date has been insignificant and has been generated from short-term research agreements with pharmaceutical companies and federal grants. There have been no multiple element arrangements. Revenue is recognized when four basic criteria are met: (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the fee is fixed or determinable, and (4) collectability is reasonably assured. Accordingly, the Company has recognized revenue under its agreements as the services were performed.

Comprehensive Loss — Comprehensive loss consists of net loss and changes in equity during a period from transactions and other equity and circumstances generated from non-owner sources. The Company had no items of comprehensive loss, other than its net loss, for each of the periods presented.

Research and Development Costs — Research and development expenses consist of expenses incurred in performing research and development activities, including compensation and benefits for full-time research and development employees, an allocation of facilities expenses, overhead expenses, manufacturing process-development and scale-up activities, clinical trial and related clinical manufacturing expenses, fees paid to clinical research organizations, or CROs, and investigative sites, payments to universities under the Company’s license agreements and other outside expenses. In the early phases of development, the Company’s research and development costs are often devoted to expanding its product platform and are not necessarily allocable to a specific target. Research and development costs are expensed as incurred. Nonrefundable advanced payments, if any, for goods and services used in research and development are recognized as an expense as the related goods are delivered or services are performed.

Preferred Stock Warrant Liability — Freestanding warrants related to shares that are redeemable or contingently redeemable are classified as a liability on the Company’s balance sheets. The Company uses the Black-Scholes option-pricing model to estimate the fair value of the warrants. Changes in the fair value of these warrants are recorded in the statements of operations. All of the Company’s warrants to purchase preferred stock were converted to warrants to purchase common stock upon the Company’s IPO in April 2014. Accordingly, the preferred stock warrant liability was reclassified to additional paid-in capital.

Redeemable Convertible Preferred Stock — The Company classifies redeemable convertible preferred stock that is redeemable outside of the Company’s control outside of permanent equity. The Company recorded such redeemable preferred stock at fair value upon issuance, net of any issuance costs or discounts, and the carrying value is being increased by periodic accretion to its redemption value. In the absence of retained earnings these accretion charges are recorded against additional paid-in capital, if any, and then to accumulated deficit. The Company amortizes the accretion using the interest method. All of the Company’s redeemable convertible preferred stock was automatically converted to common stock in connection with the Company’s IPO in April 2014.

Stock-Based Compensation — The Company accounts for stock-based awards at fair value, which is measured using the Black-Scholes option-pricing model. The fair value measurement date for employee awards is generally the date of grant. The fair value measurement date for nonemployee awards is generally the date the performance of services is completed. Stock-based compensation costs are recognized as an expense over the requisite service period, which is generally the vesting period, on a straight-line basis for all time-vested awards. The Company issued performance based grants where the vesting of the grant is tied to certain milestone performance and in these cases, the compensation is recognized as expense when the probability of the milestone is met.

Stock-based awards to nonemployees are remeasured at each reporting date and recognized as services are rendered, generally on a straight-line basis. The Company believes that the fair value of these awards is more reliably measurable than the fair value of the services rendered. Stock-based compensation is classified in the accompanying consolidated statements of operations in the department where the related services are provided.

Net Loss per Share Attributable to Common Stockholders — Basic net loss attributable to common stockholders per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. During periods where the Company might earn net income, the Company would allocate participating securities a proportional share of net income determined by dividing total weighted average participating securities by the sum of the total weighted average common shares and participating securities (the “two-class method”). Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods where the Company incurred net loss, the Company allocates no loss to participating securities because they have no contractual obligation to share in the losses of the Company. The Company computes diluted loss per common share after giving consideration to the dilutive effect of stock options and warrants that are outstanding during the period, except where such nonparticipating securities would be antidilutive.

Income Taxes — Deferred income taxes are provided for the temporary differences arising between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and for operating loss carryforwards and credits. Deferred tax assets and liabilities are recorded using tax rates expected to be in effect in the year in which the differences are expected to reverse. A valuation allowance is provided for any net deferred tax assets for which management believes it is more likely than not that the net deferred tax assets will not be realized.

The Company provides reserves for potential payment of tax to various tax authorities related to uncertain tax positions. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its filings or positions is “more likely than not” to be realized following resolution of any uncertainty related to the tax benefit, assuming the matter in question will be raised by the tax authorities. Potential interest and penalties associated with such uncertain tax positions are recorded as a component of income tax expense. At December 31, 2014 and 2013, the Company has not identified any significant uncertain tax positions.

Guarantees and Indemnification — As permitted under Delaware law, the Company indemnifies its officers, directors, and employees for certain events or occurrences while the officer or director is, or was serving at the Company’s request in such a capacity. The term of the indemnification is for the officer’s or director’s lifetime.

Recent Accounting Pronouncements — In August 2014 Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2014-15, “Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern” (“ASU 2014-15”). ASU 2014-15 requires management to evaluate, at each annual and interim reporting period, whether there are conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern and provide related disclosures. ASU 2014-15 is effective for annual and interim reporting periods beginning January 1, 2017 and is not expected to have a material impact on the Company’s consolidated financial statements.

In June 2014, the FASB issued ASU No. 2014-10, “Development Stage Entities: Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation.” This accounting standard eliminates all incremental financial reporting requirements from U.S. GAAP for development stage entities, thereby improving financial reporting by reducing the cost and complexity associated with providing such information. The Company will no longer be required to present inception-to-date information. This ASU is effective on a prospective basis for annual and interim reporting periods beginning on or after December 15, 2014, with early adoption permitted. The Company elected to early adopt the ASU starting with its June 30, 2014 financial statements and, accordingly, has not included inception to date information it the accompanying financial statements.

- Definition

The entire disclosure for all significant accounting policies of the reporting entity.

+ References+ Details

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

3.	NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS

The following table summarizes the computation of basic and diluted net loss per share attributable to common stockholders of the Company (in thousands, except share data and per share data):

	Years Ended December 31,
	2014			2013			2012
Net loss	$	(23,342	)	$	(17,143	)	$	(22,101	)
Accretion of preferred stock issuance costs to redemption value		—			—			(73	)
Net loss attributable to common stockholders — basic and diluted	$	(23,342	)	$	(17,143	)	$	(22,174	)
Weighted-average number of common shares — basic and diluted		14,548,516			684,330			609,344
Net loss per share attributable to common stockholders — basic and diluted	$	(1.60	)	$	(25.05	)	$	(36.39	)

The Company has reported a net loss for all periods presented, therefore diluted net loss per common share is the same as basic net loss per common share.

The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted-average shares outstanding, because such securities had an antidilutive impact due to the losses reported (in common stock equivalent shares):

	As of December 31,
	2014		2013		2012
Options to purchase common stock		2,126,176		1,062,694		1,046,178
Warrants to purchase redeemable convertible preferred stock		—		128,663		128,663
Warrants to purchase common stock		128,663		—		—
Redeemable convertible preferred stock		—		6,826,004		6,992,694
Convertible notes payable		—		754,785		—

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Property and Equipment

12 Months Ended

Dec. 31, 2014

Property Plant And Equipment [Abstract]

Property and Equipment

4.	PROPERTY AND EQUIPMENT

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

	As of December 31,
	2014			2013
Laboratory equipment	$	1,163		$	1,246
Computer equipment		260			183
Office furniture and equipment		292			257
Leasehold improvements		117			91
		1,832			1,777
Less accumulated depreciation and amortization		(1,490	)		(1,532	)
Property and equipment, net	$	342		$	245

Depreciation and amortization expense for the years ended December 31, 2014, 2013 and 2012 was $126,000, $197,000 and $346,000, respectively.

- Definition

The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures.

+ References+ Details

Accrued Expenses

12 Months Ended

Dec. 31, 2014

Payables And Accruals [Abstract]

Accrued Expenses

5.	ACCRUED EXPENSES

Accrued expenses consist of the following (in thousands):

	As of December 31,
	2014		2013
Accrued expenses	$	663	$	379
Accrued clinical trial costs		848		610
Accrued contract manufacturing expenses		580		433
Accrued compensation and benefits		983		618
Accrued interest		574		234
Total accrued expenses	$	3,648	$	2,274

Convertible Notes Payable to Shareholders

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Convertible Notes Payable to Shareholders

6.	CONVERTIBLE NOTES PAYABLE TO SHAREHOLDERS

In May 2010 and September 2010, the Company issued one-year convertible notes payable in the amounts of $5,000,000 and $1,500,000, respectively, to existing investors, with a stated interest rate of 7%. In November 2010, the principal and accrued interest of $176,000 were converted into 9,021,175 shares of Series C Preferred Stock at $0.74 per share. The Company also provided for the issuance of seven-year warrants to purchase Series C Preferred Stock with the notes. The issuance of the warrants was contingent upon the conversion of the notes to Series C Preferred Stock. The number of shares included in the warrants was determined by dividing 10% of the note principal converted to Series C Preferred Stock by the Series C Preferred Stock per share issue price. Concurrent with the conversion of the notes, warrants to purchase 878,370 shares of Series C Preferred Stock at $0.74 per share became exercisable. The Company estimated the fair value of the warrants on the issue date to be $474,000 using the Black-Scholes option-pricing model with the following assumptions: volatility of 80%, contractual term of seven years, risk-free interest rate of 1.85%, and no dividend yield. The Company determined the fair value of the warrants at the end of each subsequent reporting period using the Black-Scholes option-pricing model (see Note 11) until their conversion to warrants to purchase 60,532 shares of common stock upon the IPO in April 2014.

In August 2013, the Company issued convertible promissory notes in the amount of $8,824,000 to existing investors, with a stated interest rate of 7%. Outstanding principal and unpaid accrued interest due under the notes were automatically converted into shares of the Company’s common stock upon the closing of the Company’s IPO in April 2014.

In February and March 2014, the Company issued convertible promissory notes in the aggregate amount of $6,000,000 to existing investors and a convertible promissory note in the amount of $2,500,000 to a new investor. All the notes had a stated interest rate of 7%. Outstanding principal and unpaid accrued interest due under the notes were automatically converted into shares of the Company’s common stock upon the closing of the Company’s IPO in April 2014, at a conversion price equal to 77.5% of the IPO price. The Company recorded a loss on the extinguishment of the notes of $2,493,000 in April 2014, equal to the difference between the fair value of the shares into which the notes converted and the carrying amount of the notes upon the closing of the Company’s IPO.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References+ Details

Loan Agreements

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Loan Agreements

7.	LOAN AGREEMENTS

In August 2008, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with a bank to borrow up to $1,500,000 in one or more advances to finance certain equipment purchases made by the Company through May 31, 2009. In September 2008, the Company received its only advance totaling $695,000 and issued a note payable to the bank. No additional advances were made. The note was payable over a 48-month period in equal principal payments, plus interest on the outstanding balance, fixed at the 8.75%. The note was secured by a security interest in the specific equipment financed. In September 2012, the Company paid the remaining balance in accordance with the original repayment schedule.

In connection with the Loan Agreement, the Company issued the bank a warrant to purchase 15,000 shares of the Company’s Series B Preferred Stock at an exercise price of $2.00 per share. The warrant was immediately exercisable and expires 10 years from the date of grant. The value of the warrant was recorded as a discount to the note payable and was amortized to interest expense using the effective interest method over the 48-month repayment term. The Company estimated the fair value of the warrant on the grant date to be $25,000 using the Black-Scholes option-pricing model with the following assumptions: volatility of 79%, contractual term of 10 years, risk-free interest rate of 3.89%, and no dividend yield. The Company determined the fair value of the warrants at the end of each subsequent reporting period using the Black-Scholes option pricing model (see Note 11) until their conversion to common stock warrants to purchase 1,695 shares of common stock upon the completion of the IPO in April 2014.

In December 2011, the Company entered into a loan and security agreement with Lighthouse Capital Partners VI, L.P. (“Lighthouse Capital”) to borrow up to $10,000,000 in one or more advances by December 31, 2012. Debt proceeds are available to the Company to fund research and development activities and other general corporate purposes. The Company granted Lighthouse Capital a first priority security interest in all unsecured present and future assets, other than intellectual property, and the Company entered into a negative pledge agreement with the lender, whereby the Company agrees not to grant a security interest in or encumber any of the Company’s intellectual property. The Company also has restrictions on its ability to obtain additional debt that is not permitted under the agreement. In both March 2012 and August 2012, the Company borrowed $5,000,000 under the loan and security agreement, for a total of $10,000,000. This amount was being repaid over 36 months beginning on December 1, 2012, at an interest rate of 8.25%.

In addition, the Company is required to make an additional interest payment in the amount of $600,000 at the end of the loan term. The amount is being accrued over the loan term as interest expense. The amount accrued as of December 31, 2014 was $574,000 and is included in accrued expense in the accompanying balance sheet. As of December 31, 2013 the amount accrued was $391,000, and was included as non-current accrued interest expense in the accompanying balance sheet. The minimum future principal payments are as follows (in thousands):

Year Ending December 31,
2015	$	3,321
Unamortized discount relating to warrants		(197	)
Total		3,124
Less current portion		(3,124	)
Long-term portion	$	-

In January 2015, the Company repaid in full the amount outstanding under the Lighthouse Capital loan with the proceeds from a new loan (see Note 18).

In connection with the loan and security agreement with Lighthouse Capital, the Company issued the lender a warrant to purchase a maximum of 66,436 shares of the Company’s Series D Preferred Stock, at an exercise price of $12.04 per share. The warrant was immediately exercisable for 29,067 shares at the date of issue and expires 10 years from the date of issue (December 2021). The exercisable shares increased in March 2012 and August 2012 as the Company borrowed under the loan and security agreement. At December 31, 2014 and 2013, 66,436 shares were exercisable. The fair value of the warrant was estimated on the date of issue for the exercisable shares at that date and the fair value of each increment was estimated on the date the shares became exercisable, using the Black-Scholes option-pricing model. The Company estimated the fair value of the warrant for shares exercisable on the issue date in December 2011 and incremental shares exercisable in March 2012 and August 2012 to be $284,000, $182,000 and $178,000, respectively. The following table shows the Black-Scholes assumptions used to value the preferred stock warrants in connection with the loan and security agreement on the respective dates:

	Series D Preferred Stock Warrants
	December 2011			March 2012			August 2012
Contractual life	10 years			9.69 years			9.29 years
Volatility rate		80	%		80	%		80	%
Risk-free interest rate		1.98	%		2.17	%		1.68	%
Expected dividends		—			—			—

The value of the warrant is recorded as a discount to the loan and is being amortized to interest expense using the effective interest method over the 36-month repayment term.

The Company determined the fair value of the warrant at the end of each subsequent reporting period using the Black-Scholes option pricing model (see Note 11) until their conversion to warrants to purchase 66,436 shares of common stock upon the completion of the IPO in April 2014.

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2014

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock

8.	REDEEMABLE CONVERTIBLE PREFERRED STOCK

In connection with the closing of the IPO in April 2014, all of the Company’s outstanding convertible preferred stock automatically converted to common stock resulting in an additional 6,826,004 shares of common stock of the Company becoming outstanding.

As of December 31, 2013, preferred stock consisted of the following (in thousands, except share data):

	Preferred Shares Authorized		Issuance Date	Preferred Shares Issued and Outstanding		Redemption Value /Liquidation Preference		Carrying Value
Seed		2,500,000	December 2006		2,500,000	$	2,000	$	2,000
Series A		9,307,692	May 2007		9,307,692		12,100		12,100
Series B		4,077,500	December 2007		3,562,500		7,125		7,125
Series B-1		5,000,000	July 2009		4,842,500		9,685		9,685
Series C		33,310,787	November 2010 and June 2011		31,836,392		23,559		23,094
Series D		34,698,793	December 2011 and November 2012		33,158,272		27,521		27,521
		88,894,772			85,207,356	$	81,990	$	81,525

Stockholder's Equity (Deficit)

12 Months Ended

Dec. 31, 2014

Stockholders Equity Note [Abstract]

Stockholder's Equity (Deficit)

9.	STOCKHOLDERS’ EQUITY (DEFICIT)

Common Stock — As discussed in Note 1, during 2014 the Company issued 19,297,952 shares of common stock in connection with its IPO, the conversion of preferred stock and convertible notes into common stock, and the partial exercise of the underwriters’ overallotment option in the IPO.

Reserved Shares of Common Stock — The Company has reserved the following number of shares of common stock at December 31, 2014 and 2013:

	As of December 31,
	2014		2013
Redeemable convertible preferred stock		—		6,954,691
Warrants to purchase common stock		128,663		—
Common stock options		3,561,104		1,201,770
Total		3,689,767		8,156,461

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Stock Option Plans

12 Months Ended

Dec. 31, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Plans

10.	STOCK OPTION PLANS

2007 Stock Incentive Plan – The Company’s 2007 Incentive Stock Plan, or the 2007 Plan, provides for the grant of qualified incentive stock options and nonqualified stock options or other awards to the Company’s employees, officers, directors, advisors, and outside consultants to purchase up to an aggregate of 1,275,211 shares of the Company’s common stock, as amended in January 2014. The stock options generally vest over a four-year period and expire 10 years from the date of grant. Certain options provide for accelerated vesting if there is a change in control, as defined in the 2007 Plan. Effective with the IPO, no additional grants will be issued from the 2007 Plan and all shares available for grant under the 2007 Plan were transferred to the 2014 Plan. Accordingly, at December 31, 2014, there were no shares available for future grant under the 2007 Plan. At December 31, 2013, there were 139,076 shares available for future grant under the 2007 Plan.

Prior to the IPO, in determining the exercise prices for options granted, the Company’s board of directors considered the fair value of the common stock as of the measurement date. The fair value of the common stock was determined by the board of directors at each award grant date based upon a variety of factors, including the results obtained from a common stock valuation, the Company’s financial position and historical financial performance, the status of technological developments within the Company’s products, the composition and ability of the current research and management team, an evaluation or benchmark of the Company’s competition, the current business climate in the marketplace, the illiquid nature of the common stock, arm’s-length sales of the Company’s capital stock (including redeemable convertible preferred stock), the effect of the rights and preferences of the preferred shareholders, and the prospects of a liquidity event, among others.

2014 Stock Incentive Plan – In March 2014, the Company’s board of directors adopted and its stockholders approved the 2014 Stock Incentive Plan, or the 2014 Plan, which became effective upon the closing of the IPO. The 2014 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards. As of December 31, 2014, there were 1,434,928 shares available for future grant under the 2014 Plan.

A summary of stock option activity for employee and nonemployee awards under the 2007 Plan and the 2014 Plan during the year ended December 31, 2014 is presented below:

	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding — January 1, 2014		1,062,694		$	3.98		7.2	$	7,028
Granted		1,138,170			5.99
Exercised		(41,566	)		3.36
Forfeited		(33,122	)		4.85
Outstanding — December 31, 2014		2,126,176		$	4.97		6.7	$	2,701
Options expected to vest — December 31, 2014		859,690		$	5.46		9.2	$	1,105
Options exercisable — December 31, 2014		786,623		$	4.41		3.9	$	1,541

The total intrinsic value of stock options exercised in the years ended December 31, 2014, 2013 and 2012 was $161,000, $15,000, and $0, respectively.

The weighted-average per share grant date fair value of options granted during 2014, 2013 and 2012 was $3.33, $2.90, and $2.61, respectively.

The Company has recorded stock-based compensation expense of $885,000, $622,000 and $529,000 during the years ended December 31, 2014, 2013 and 2012, respectively, which is based on the number of awards ultimately expected to vest. As of December 31, 2014, there was $2.2 million of unrecognized compensation cost related to unvested stock-based compensation arrangements granted under the 2007 Plan and the 2014 Plan. The compensation is expected to be recognized over a weighted-average period of 3.02 years at December 31, 2014.

Stock-based compensation expense recorded as research and development and general and administrative expenses is as follows (in thousands):

	As of December 31,
	2014		2013		2012
Research and development	$	317	$	284	$	187
General and administrative		568		338		342
Total	$	885	$	622	$	529

The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model based on the assumptions noted in the table below. Expected volatility for the Company’s common stock was determined based on an average of the historical volatility of a peer-group of similar public companies. The Company has limited option exercise information, as such, the expected term of the options granted was calculated using the simplified method that represents the average of the contractual term of the option and the weighted-average vesting period of the option. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. The risk-free rate for periods within the contractual life of the option is based upon the U.S. Treasury yield curve in effect at the time of grant.

The assumptions used in the Black-Scholes option-pricing model for stock options granted to employees during the years ended December 31, 2014, 2013 and 2012 are as follows:

	December 31,
	2014	2013	2012
Expected life	6 years	6 years	6 years
Risk-free interest rate	1.71%-2.00%	1.09%-1.92%	0.83%-1.12%
Expected volatility	54%-60%	59%-79%	77%-79%
Expected dividend rate	—%	—%	—%

The Company recorded stock-based compensation expense related to nonemployee awards of $56,000, $85,000 and $39,000 for the years ended December 31, 2014, 2013 and 2012, respectively. The compensation expense related to the nonemployee awards is included in the total stock-based compensation each year and is subject to re-measurement until the options vest. The Black-Scholes assumptions used to estimate the fair value of these awards for the years ended December 31, 2014, 2013 and 2012 were as follows:

	December 31,
	2014	2013	2012
Expected life	8 years	7 years	6 years
Risk-free interest rate	1.86%-2.53%	1.11%-2.86%	0.99%-2.05%
Expected volatility	56%-62%	56%-79%	76%-79%
Expected dividend rate	—%	—%	—%

The Company did not grant any nonemployee stock option grants in 2014 or in 2013, except for a performance award grant in 2013 to the Company’s board chairman for non-board related services. During the year ended December 31, 2014, the board of directors changed the vesting conditions of this award from performance-based vesting to time-based vesting and reduced the total number of shares subject to the stock option. As a result, the 16,000 shares subject to this stock option now vest over three years, with the first third vesting on March 26, 2014. The change in vesting condition was accounted for as a modification of this stock option, which had an immaterial impact on the Company’s financial statements.

In 2013 and 2012, the Company granted to the Company’s Chief Executive Officer (“CEO”) options to purchase up to 53,489 and 56,053 shares of common stock, respectively. The vesting of these awards was contingent upon either (i) a change of control at a minimum price per share or (ii) the registration of the Company’s common stock under the Securities Exchange Act of 1934 and the stock being quoted, listed or traded on an over-the-counter market or national securities exchange at a certain price per share. The CEO resigned in October 2014 and although the Company completed its IPO in April 2014, the minimum price per share required was never achieved therefore these awards will not vest. Also in 2012, the Company granted options to purchase 60,934 common shares to a second Company officer that will vest upon the achievement of business milestones as defined within the stock option agreement. These awards have not vested as of December 31, 2014. Compensation expense for the awards will be recorded if and when the awards are determined to be probable.

2014 Employee Stock Purchase Plan – In March 2014, the Company’s board of directors adopted and its stockholders approved the 2014 Employee Stock Purchase Plan (the “2014 ESPP”), which became effective upon the closing of the IPO. The 2014 ESPP will be administered by the Company’s board of directors or by a committee appointed by the Company’s boa