ZS Pharma (ZSPH) Inactive 10-K13 Mar 152014 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2014	Mar. 03, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	ZSPH
Entity Registrant Name	ZS Pharma, Inc.
Entity Central Index Key	1459266
Current Fiscal Year End Date	-19
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		20,902,312
Entity Public Float			$65,017,780

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$47,402	$9,170
Short-term investments	54,878
Prepaid expenses	556	71
Other current assets	419	6
Total current assets	103,255	9,247
Property and equipment, net	12,425	4,625
Restricted cash	301	150
Other assets	181	24
Total assets	116,162	14,046
Current liabilities:
Accounts payable	4,565	1,489
Clinical trial accrual	1,244	534
Accrued liabilities	3,025	2,580
Current portion of capital lease obligation	304	73
Total current liabilities	9,138	4,676
Deferred rent	74	67
Lease incentive	92	184
Capital lease obligation	127
Long-term debt, net of discount	9,959
Total liabilities	19,390	7,594
Commitments and contingencies (Note 12)
Shareholders' equity (deficit):
Convertible preferred stock	0	0
Common stock, par $0.001; 250,000,000 and 49,574,865 shares authorized December 31, 2014 and 2013, respectively; 20,898,212 and 1,628,976 shares issued and outstanding at December 31, 2014 and 2013, respectively	21	2
Additional paid-in capital	211,059	3,854
Accumulated deficit	-114,278	-50,234
Accumulated other comprehensive loss	-30
Total shareholders' equity (deficit)	96,772	-45,182
Total liabilities and shareholders' equity (deficit)	116,162	14,046
Series B Preferred Stock [Member]
Current liabilities:
Series B redeemable preferred stock warrant liability		2,667
Shareholders' equity (deficit):
Convertible preferred stock		8,387
Series C Preferred Stock [Member]
Shareholders' equity (deficit):
Convertible preferred stock		43,247
Series A Preferred Stock [Member]
Shareholders' equity (deficit):
Convertible preferred stock		$1,196

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized	5,000,000
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	250,000,000	49,574,865
Common stock, shares issued	20,898,212	1,628,997
Common stock, shares outstanding	20,898,212	1,628,997
Series B Preferred Stock [Member]
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized		6,768,033
Convertible preferred stock, shares issued		2,261,506
Convertible preferred stock, shares outstanding		2,261,506
Convertible preferred stock, liquidation value		$8,409
Series C Preferred Stock [Member]
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized		17,692,308
Convertible preferred stock, shares issued		6,899,281
Convertible preferred stock, shares outstanding		6,899,281
Convertible preferred stock, liquidation value		$46,000
Series A Preferred Stock [Member]
Convertible preferred stock, par value	$0.00	$0.00
Convertible preferred stock, shares authorized		1,494,966
Convertible preferred stock, shares issued		582,976
Convertible preferred stock, shares outstanding		582,976

Statements_of_Operations

Statements of Operations (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Share data, unless otherwise specified	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
Costs and expenses:
Research and development	$14,574	[1]	$12,541	[1]	$11,649	[1]	$6,854	[1]	$6,880	[1]	$7,138	[1]	$6,335	[1]	$4,409	[1]	$45,618	$24,762	$6,989
General and administrative	5,535	[2]	4,081	[2]	2,881	[2]	2,422	[2]	3,521	[2]	2,224	[2]	972	[2]	715	[2]	14,919	7,432	1,148
Total cost and expenses	20,109		16,622		14,530		9,276		10,401		9,362		7,307		5,124		60,537	32,194	8,137
Loss from operations	-20,109		-16,622		-14,530		-9,276		-10,401		-9,362		-7,307		-5,124		-60,537	-32,194	-8,137
Other (income) expense:
Interest income	-43	[3]	-31	[3]	-11	[3]	-9	[3]	-5	[3]	-5	[3]	-8	[3]	-12	[3]	-94	-30	-17
Interest expense	249	[4]	272	[4]	6	[4]	3	[4]	-4	[4]	3	[4]	5	[4]	5	[4]	530	9	2,099
Expense to mark warrants to market					1,774		1,297		1,272		32		11		109		3,071	1,424	62
Net loss	-20,315		-16,863		-16,299		-10,567		-11,664		-9,392		-7,315		-5,226		-64,044	-33,597	-10,281
Preferred stock accretion					-129		-181		-174		-173		-172		-170		-310	-689	-174
Net loss attributable to common shareholders	($20,315)		($16,863)		($16,428)		($10,748)		($11,838)		($9,565)		($7,487)		($5,396)		($64,354)	($34,286)	($10,455)
Net loss per share attributable to common shareholders, basic and diluted	($0.98)		($0.81)		($4.72)		($6.60)		($7.38)		($6.14)		($4.81)		($3.46)		($5.47)	($21.84)	($6.74)
Weighted-average common shares used to compute net loss per share attributable to common shareholders, basic and diluted	20,832,475		20,818,794		3,482,340		1,628,976		1,604,490		1,557,643		1,557,643		1,557,643		11,768,267	1,569,583	1,552,276

[1]	(1) Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.
[2]	(2) Administrative expenses in the quarter ended December 31, 2013 include $650 of additional legal and professional fees, incurred primarily in support of our product development, $219 of additional consulting fees in support of medical communications and $174 of additional non-cash option expense to mark to market certain stock options recorded as liabilities
[3]	(3) Interest income in the quarters ended September 30, 2014 and December 31, 2014 include interest income on invested surplus cash.
[4]	(4) Interest expense in the quarters ended September 30, 2014 and December 31, 2014 include interest expense related to the MidCap Credit Facility initiated in July 2014 ( See note 6 above) .

Statements_of_Comprehensive_Lo

Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net loss	($64,044)	($33,597)	($10,281)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net of tax	-30
Total comprehensive loss	($64,074)	($33,597)	($10,281)

Statements_of_Redeemable_and_C

Statements of Redeemable and Convertible Preferred Stock and Shareholders' Equity (Deficit) (USD $)	Total	IPO [Member]	Equity Option [Member]	Warrant [Member]	Accretion of Series B [Member]	Accretion of Series C [Member]	Accretion of Series D [Member]	Series B Preferred Stock [Member]	Series B Preferred Stock [Member]	Series C Preferred Stock [Member]	Series C Preferred Stock [Member]	Series D Preferred Stock [Member]	Series D Preferred Stock [Member]	Series A Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Deficit [Member]
In Thousands, except Share data	Total	IPO [Member]	Equity Option [Member]	Warrant [Member]	Accretion of Series B [Member]	Accretion of Series C [Member]	Accretion of Series D [Member]	Series B Preferred Stock [Member]	Accretion of Series B [Member]	Series C Preferred Stock [Member]	Accretion of Series C [Member]	Series D Preferred Stock [Member]	Accretion of Series D [Member]	Series A Preferred Stock [Member]	Common Stock [Member]	IPO [Member]	Additional Paid-In Capital [Member]	IPO [Member]	Equity Option [Member]	Warrant [Member]	Accretion of Series B [Member]	Accretion of Series C [Member]	Accretion of Series D [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Deficit [Member]
Temporary equity, Beginning balance at Dec. 31, 2011								$2,931
Beginning balance at Dec. 31, 2011	-3,921													1,196	2		1,237								-6,356
Temporary equity, Beginning balance, shares at Dec. 31, 2011								797,569
Beginning balance, shares at Dec. 31, 2011														582,976	1,534,263
Beneficial conversion feature of convertible notes	261																261
Option exercise	24																24
Option exercise, shares	19,498														23,398
Issuance of shares, value								5,447		27,298
Issuance of shares, shares								1,463,937		4,634,516
Issuance of shares, value								5,447		27,298
Issuance of shares, shares								1,463,937		4,634,516
Warrants issued for banking services	553																553
Share-based compensation			359	33															359	33
Net loss	-10,281																								-10,281
Accretion of preferred stock					-6	-167			6		167										-6	-167
Temporary equity, Ending balance at Dec. 31, 2012								8,384		27,465
Ending balance at Dec. 31, 2012	-13,145													1,196	2		2,294								-16,637
Temporary equity, Ending balance, shares at Dec. 31, 2012								2,261,506		4,634,516
Ending balance, shares at Dec. 31, 2012														582,976	1,557,661
Write off balance of beneficial conversion feature								-3
Issuance of shares, value										15,100
Issuance of shares, shares										2,264,765
Issuance of shares, value										15,100
Issuance of shares, shares										2,264,765
Warrant exercise, value	265																265
Warrant exercise, shares															71,336
Share-based compensation			1,983																1,983
Net loss	-33,597																								-33,597
Accretion of preferred stock					-6	-682			6		682										-6	-682
Temporary equity, Ending balance at Dec. 31, 2013								8,387		43,247
Ending balance at Dec. 31, 2013	-45,182													1,196	2		3,854								-50,234
Temporary equity, Ending balance, shares at Dec. 31, 2013								2,261,506		6,899,281
Ending balance, shares at Dec. 31, 2013														582,976	1,628,997
Option exercise	157																157
Option exercise, shares	79,441														79,441
Issuance of shares, value	-5	112,119								25		24,756				7	-5	112,112
Issuance of shares, shares												1,858,012				6,836,111
Issuance of shares, value	-5	112,119								25		24,756				7	-5	112,112
Issuance of shares, shares												1,858,012				6,836,111
Warrant exercise, value					5,737				1,405								2,374				5,737
Warrant exercise, shares									377,752						374,210
Elimination of fractional shares created by reverse stock split								-27		-6		-4		-11	-26
Conversion of Preferred shares to Common, value	78,130							-9,794		-43,563		-24,773		-1,196	12		79,314
Conversion of Preferred shares to Common, shares								-2,639,231		-6,899,275		-1,858,008		-582,965	11,979,479
Share-based compensation	7,668																7,668
Reclass of Liability options to Equity options	158																158
Net loss	-64,044																								-64,044
Other comprehensive loss	-30																							-30
Accretion of preferred stock					-2	-291	-17		2		291		17								-2	-291	-17
Ending balance at Dec. 31, 2014	$96,772														$21		$211,059							($30)	($114,278)
Ending balance, shares at Dec. 31, 2014															20,898,212

Statements_of_Redeemable_and_C1

Statements of Redeemable and Convertible Preferred Stock and Shareholders' Equity (Deficit) (Parenthetical) (IPO [Member], USD $)	0 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jun. 23, 2014	Dec. 31, 2014
IPO [Member]
Payments of Stock Issuance Costs	$2.30	$10.90

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($64,044)	($33,597)	($10,281)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,340	705	49
Amortization of lease incentive	-92	-18
Stock-based compensation	7,668	2,142	233
Warrant expense			33
Series B warrant mark-to-market expense	3,071	1,424	62
Other	-1
Amortization of deferred debt issuance costs	19	0	1,814
Amortization of debt discount	131
Amortization of premium on marketable securities	107
Interest expense repaid in Series B preferred stock upon conversion of convertible notes			278
Loss on disposal of assets and other noncash income		-2
Changes in operating assets and liabilities:
Prepaid expenses and other assets	-1,083	-84	-6
Accounts payable	2,543	505	488
Clinical trial accrual	839	67
Accrued expenses	474	2,262	142
Deferred rent	7	67
Net cash used in operating activities	-49,021	-26,529	-7,174
Investing activities
Purchases of property and equipment	-7,999	-3,771	-706
Purchase of short-term investments	-54,889
Net cash used in investing activities	-62,888	-3,771	-706
Financing activities
Proceeds from issuance of note payable, net of issuance costs	9,828		925
Payment of debt issuance costs for long-term debt	-115		24
Proceeds from exercise of stock options	157
Proceeds from exercise of warrants	3,780	265
Proceeds from issuance of common stock, net of issuance costs	112,117
Principal payments on capital lease	-251	-146	-73
Restricted cash	-151	-150
Net cash provided by financing activities	150,141	15,069	28,633
Net increase (decrease) in cash and cash equivalents	38,232	-15,231	20,753
Cash and cash equivalents at beginning of period	9,170	24,401	3,648
Cash and cash equivalents at end of period	47,402	9,170	24,401
Supplemental disclosures of cash flow information
Cash paid for interest	318	12	6
Cash paid for taxes	44	7	21
Non-cash investing and financing activities:
Non-cash additions to property and equipment	1,142	363	317
Series C Preferred Stock [Member]
Financing activities
Proceeds from issuance of preferred stock, net of issuance costs	25	15,100	27,757
Series D Preferred Stock [Member]
Financing activities
Proceeds from issuance of preferred stock, net of issuance costs	24,751
Series B Warrant [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Series B warrant mark-to-market expense	$3,071	$1,424	$76

Nature_of_Business_and_Summary

Nature of Business and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Nature of Business and Summary of Significant Accounting Policies

1. Nature of Business and Summary of Significant Accounting Policies

Description of Organization

ZS Pharma, Inc. is a biopharmaceutical company focused on the development and commercialization of highly selective, non-absorbed drugs to treat renal, cardiovascular, liver and metabolic diseases. Our proprietary zirconium silicate technology allows us to create highly selective ion traps that can reduce toxic levels of specific electrolytes without disturbing the balance of other electrolytes. Our lead product candidate, sodium zirconium cyclosilicate, (or ZS-9), recently completed Phase III development for the treatment of hyperkalemia, a life-threatening condition in which elevated levels of potassium increase the risk of muscle dysfunction, including cardiac arrhythmias and sudden cardiac death. We expect to file a New Drug Application (NDA) for ZS-9 for the treatment of hyperkalemia within the first half of 2015.

On June 17, 2014, our registration statement on Form S-1 (File No. 333-195961) relating to our initial public offering (IPO) of our common stock was declared effective by the Securities and Exchange Commission (SEC). Our shares began trading on The NASDAQ Global Select Market on June 18, 2014. The public offering price of the shares sold in the offering was $18.00 per share. The IPO closed on June 23, 2014 and included 6,836,111 shares of common stock, which included 891,667 shares of common stock issued pursuant to the option granted to the underwriters to purchase additional shares. We received total proceeds from the offering to us, net of underwriting discounts and commissions of $8.6 million, of approximately $114.4 million. After deducting offering expenses of approximately $2.3 million, net proceeds were approximately $112.1 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 11,979,479 shares of common stock.

Upon the effectiveness of the Amended and Restated Certificate of Incorporation of the Company on June 23, 2014, the number of shares of capital stock the Company is authorized to issue was increased to 255,000,000 shares, of which 250,000,000 shares are common stock and 5,000,000 shares are preferred stock. Both the common stock and preferred stock have a par value of $0.001 per share. There were no shares of preferred stock outstanding at September 30, 2014.

Basis of Presentation Including Liquidity

The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP), which contemplate continuation of the Company as a going concern. The Company has financed its operations from inception primarily through sales of common and preferred stock, and financing under debt arrangements. The future success of the Company is dependent on its ability to develop its product candidate and ultimately upon its ability to attain profitable operations. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology, and market acceptance of the Company’s products. As a result of the aforementioned factors and the related uncertainties, there can be no assurance of the Company’s future success. As of December 31, 2014, the Company has an accumulated deficit of $114.3 million and may require substantial additional capital for research, product development and commercialization of ZS-9. The Company believes its cash, cash equivalents and short-term investments at December 31, 2014, totaling $102.3 million as well as its ability to draw $10 million on its MidCap Credit Facility (see Note 6) are sufficient to fund operations for a period of at least 12 months from the balance sheet date based on projected 2015 cash needs. The accompanying financial statements do not include any adjustments that might be necessary if the Company is unable to continue as a going concern.

Reverse Stock Split

In June 2014, our board of directors and our stockholders approved an amendment to our amended and restated certificate of incorporation to effect a reverse split of shares of our common stock on a 1-for-2.56437 basis (the Reverse Stock Split). The par values and the authorized shares of the common and convertible preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common stock, convertible preferred stock, options for common stock, warrants for common and preferred stock, and per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The Reverse Stock Split was made effective on June 11, 2014.

Cash, Cash Equivalents and Short-Term Investments

Our cash equivalents consist of highly liquid investments with maturities of 90 days or less at the date of purchase. Our marketable debt and equity securities have been classified and accounted for as available-for-sale. We determine the appropriate classification of our investments at the time of purchase and reevaluate the designations at each balance sheet date. We invest in highly-rated securities, and our investment policy limits the amount of credit exposure to any one issuer, industry group and currency. The policy requires investments to be investment grade, with the primary objective of minimizing the potential risk of principal loss and providing liquidity of investments sufficient to meet our operating and capital spending requirements and debt repayments. No security in our portfolio shall have a maturity date greater than 12 months at the time of purchase.

We classify our marketable securities as either short-term or long-term based on each instrument’s underlying contractual maturity date and as to whether and when we intend to sell a particular security prior to its maturity date. Marketable securities with maturities greater than 90 days at the date of purchase and 12 months or less remaining at the balance sheet date will be classified as short-term. Our marketable securities are carried at fair value, with the unrealized gains and losses, net of taxes, reported in accumulated other comprehensive loss as a component of stockholders’ equity. Fair values are determined for each individual security in the investment portfolio.

Realized gains and losses on the sale of securities are determined by specific identification of each security’s cost basis. We may sell certain of our marketable securities prior to their stated maturities for strategic reasons including, but not limited to, anticipation of credit deterioration and liquidity and duration management.

We continually review our available for sale securities to determine whether a decline in fair value below the carrying value is other than temporary. When evaluating an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, and our intent to sell, or whether it is more likely than not it will be required to sell the investment before recovery of the investment’s cost basis. Once a decline in fair value is determined to be other than temporary, an impairment charge is recorded and a new cost basis in the investment is established. If we do not intend to sell the debt security, but it is probable that we will not collect all amounts due, then only the impairment due to the credit risk would be recognized in earnings and the remaining amount of the impairment would be recognized in accumulated other comprehensive loss within stockholders’ equity.

The Company places its cash with institutions with high credit quality. However, at certain times such cash may be in excess of Federal Deposit Insurance Corporation and Securities Investor Protection Corporation insurance limits.

Restricted Cash

On November 22, 2013, the Company executed an agreement to pledge, assign, transfer, and grant a security interest to J.P. Morgan Bank to secure the payment and performance of the Company’s credit card program. The Company agreed to maintain $150,000 in a restricted cash account, given it is a pre-revenue company. In August 2014, the credit limit of the program was increased from $150,000 to $300,000 and at that time we increased the balance in the restricted cash account by $150,000.

Property and Equipment

Property and equipment are recorded at cost. Equipment under a capital lease is stated at the present value of minimum lease payments at lease inception. Depreciation is computed on a straight-line basis over the estimated useful lives of the respected assets. The useful lives of property and equipment are as follows:

Production equipment

7 years

Office equipment

3–8 years

Lab equipment

3–8 years

Impairment of Long-Lived Assets

The Company reviews long-lived assets, including property and equipment, for impairment when events or changes in business conditions indicate that their carrying value may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. There have been no impairment charges related to long-lived assets from inception through December 31, 2014.

Licenses and Patents

Licenses and patent costs are expensed as incurred. Licenses are classified as research and development expenses, and patents are classified as general and administrative expenses in the statements of operations.

Research and Development Expenses

Research and development expenses are expensed as incurred. Research and development expenses represent costs associated with the ongoing development of ZS-9, the Company’s lead development compound, and include salaries, supplies, stock compensation and expenses for clinical trials and preclinical research.

Redeemable Preferred Stock Warrant Liability

Freestanding warrants for shares that are either puttable or redeemable are classified as liabilities on the balance sheet and are carried at their estimated fair value. As further discussed in Note 7, the Series B Redeemable Preferred Stock, which was able to be purchased with the warrants, was redeemable at a future date in 2017. As such, these warrants were classified as liabilities and at the end of each reporting period, changes in the estimated fair value during the period were recorded in other income (expense). Prior to June 17, 2014, the warrants were all exercised into Series B Redeemable Preferred Stock, which was converted into Common Stock upon the IPO, and the amount of warrant liability was reclassified to shareholders’ equity.

Fair Value Measurements

ASC 820, Fair Value Measurement, provides a comprehensive framework for measuring the fair value of assets and liabilities, which provides for consistency in how fair value determinations are made under various existing accounting standards that permit, or in some cases require, estimates of fair market value. Certain financial assets and liabilities are measured at fair value on a recurring basis in the financial statements. The hierarchy ranks the quality and reliability of inputs, or assumptions, used in the determination of fair value and requires financial assets and liabilities carried at fair value to be classified and disclosed in one of the following three categories:

•

Level 1 – quoted prices in active markets for identical assets and liabilities;

•

Level 2 – inputs other than Level 1 quoted prices that are directly or indirectly observable; and

•

Level 3 – unobservable inputs that are not corroborated by market data.

Financial assets and liabilities that have recurring fair value measurements are shown below as of December 31 (in thousands):

Fair Value Measurements at

December 31, 2014 Using

Quoted Prices in

Significant

Active Markets

Other

Unobservable

for

Observable

Inputs

Identical

Inputs

Assets

Description

Total

Level 1

Level 2

Level 3

Financial Assets:

Corporate Bonds

42,768

—

42,768

—

Commercial Paper

7,699

—

7,699

—

Government Securities

4,411

—

4,411

—

Total financial assets

54,878

—

54,878

—

Fair Value Measurements at

December 31, 2013 Using

Quoted Prices in

Significant

Active Markets

Other

Unobservable

for

Observable

Inputs

Identical

Inputs

Assets

Description

Total

Level 1

Level 2

Level 3

Financial liabilities:

Series B Redeemable Preferred Stock warrants

2,667

—

2,667

Total financial liabilities

2,667

—

2,667

Level 3 liabilities comprise redeemable preferred stock warrant liabilities. These warrants were classified as liabilities because the Series B Redeemable Preferred shares that were able to be purchased by these warrants were redeemable and, therefore, were classified as temporary equity. The following table sets forth a summary of the changes in the estimated fair value of the Company’s redeemable preferred stock warrants, which were measured at fair value on a recurring basis since inception (in thousands):

Balance as of December 31, 2011

968

Issuance of redeemable preferred stock warrants

213

Net increase in fair value included in other (income) expense

Balance as of December 31, 2012

1,243

Net increase in fair value included in other (income) expense

1,424

Balance as of December 31, 2013

2,667

Net increase in fair value

3,071

Amount reclassified to shareholders’ equity upon exercise

(5,738

)

Balance as of December 31, 2014

—

Level 2 available-for-sale securities primarily consisted of: (i) bonds and notes issued by the United States government and its agencies, domestic and foreign corporations and foreign governments; and (ii) preferred securities issued by domestic and foreign corporations. The estimated fair values of these securities are determined using various valuation techniques, including a multi-dimensional relational model that incorporates standard observable inputs and assumptions such as benchmark yields, reported trades, broker/dealer quotes, issuer spreads, benchmark securities, bids/offers and other pertinent reference data.

The fair value of the outstanding Series B Redeemable Preferred Stock warrants was measured using the Black-Scholes option-pricing model. Inputs used to determine estimated fair value included the estimated fair value of the warrant, as determined by the fair value of the underlying stock relative to the warrant exercise price at the valuation measurement date, volatility of the price of the underlying stock, the remaining contractual term of the warrants, risk-free interest rates, and expected dividends.

The Company believes the recorded values of cash and cash equivalents, other current assets, accounts payable, and accrued expenses approximate fair value because of the short maturity of these financial instruments.

Share-Based Compensation

The Company accounts for its equity-based compensation in accordance with ASC 718, Compensation — Stock Compensation, which requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and directors to be recognized in the financial statements, based on their fair value. The value of awards ultimately expected to vest is recognized as expense over the requisite service periods in the Company’s statements of operations.

The Company measures equity-based compensation to non-employees in accordance with ASC 505-50, Equity-Based Payments to Non-Employees, and recognizes the fair value of the award over the period the services are rendered or goods are provided.

The Company has one share-based compensation plan, the 2014 Incentive Plan, as amended from time to time, which is more fully described in Note 8. Share-based compensation expense recognized in the statements of operations was $7.7 million and $2.1 million for the fiscal years ended December 31, 2014 and 2013, respectively. These amounts include $0.2 million of share-based compensation related to options issued to non-employees, which are recorded as liabilities at December 31, 2013.

The Company records the expense attributed to nonemployee services paid with share-based awards based on the estimated fair value of the awards determined using the Black-Scholes option pricing model. The measurement of stock-based compensation for nonemployees is subject to re-measurement as the options vest, and the expense is recognized over the period during which services are received.

In addition to stock options, the Company provided restricted stock to certain employees and consultants in 2008 that vested through 2010, resulting in a cumulative compensation expense of $69,976 that the Company classified as stock compensation expense during these periods.

Income Taxes

The Company accounts for income taxes using the asset and liability approach in accordance with the provision of ASC 740, Income Taxes. Under this approach, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company continues to record a valuation allowance for the full amount of deferred tax assets, which would otherwise be recorded for tax benefits relating to the operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of December 31, 2014, the Company had no uncertain tax positions and no interest or penalties have been charged to the Company from inception through December 31, 2014. If incurred, the Company will classify any interest and penalties as a component of tax expense.

We have determined that we have had several changes of ownership, as defined under Internal Revenue Code Section 382 (Section 382), since the company was founded in 2008, with the most recent Section 382 change of ownership occurring on June 23, 2014. According to the provisions of Section 382, our net operating losses and research credits will be subject to certain annual limitations. As of December 31, 2014, we had federal income tax net operating loss, or NOL, carryforwards of approximately $93.7 million and federal research tax credit carryforwards of approximately $5.2 million, net of limitations pursuant to Section 382 of the Code.

Use of Estimates

The preparation of the financial statements in accordance with U.S. generally accepted accounting principles requires management to make certain estimates and judgments that affect the reported amounts of assets, liabilities, and expenses. Actual results could differ from those estimates.

The Company estimates its clinical trial expense accrual for a given period based on the number of patients enrolled at each site and the length of time each patient has been in the trial, less amounts previously billed.

Prior to its IPO, the Company utilized significant estimates and assumptions in determining the fair value of its Common Stock. Management determined the estimated fair value of the Company’s Common Stock based on a number of objective and subjective factors, including external market conditions affecting the biotechnology industry sector and the prices at which the Company sold shares of convertible preferred stock; the superior rights and preferences of securities senior to the Company’s Common Stock at the time; and the likelihood of achieving a liquidity event, such as an IPO or sale of the Company.

The Company engaged third-party valuation specialists to assist in estimating the fair value of its Common Stock and in performing valuation analyses as of the grant or other valuation dates in 2013 and prior periods. The valuation specialists utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants, or AICPA, Audit and Accounting Practice Aid Series: Valuation of Privately-Held Company Equity Securities Issued as Compensation, or the AICPA Practice Aid. The methodologies included the Option Pricing Method utilizing the Backsolve Method (a form of the market approach defined in the AICPA Practice Aid) and the Probability-Weighted Expected Return Method based upon the probability of occurrence of certain future liquidity events such as an initial public offering or sale of the Company. Each valuation methodology included estimates and assumptions that required the Company’s judgment. Significant changes to the key assumptions used in the valuations could result in different fair values of Common Stock at each valuation date.

Reclassifications

During 2014, prior-period amounts for medical affairs expenses previously presented as administrative expenses are now presented as research and development expenses in the consolidated statements of income to conform to the current year’s presentation. Medical Affairs is a subset of clinical development focused on interfacing with key physician researchers to help refine clinical trial design, review and analyze results of our clinical trials, and work with key clinical investigators to help them disseminate trial results to other physicians and patients through publications and presentations. The amount of Medical Affairs expenses reclassified for 2013 and 2012 were $254,000 and $0, respectively.

During 2014, the Company determined that the holding period for restricted cash used to secure the payment and performance of the Company’s credit card program would be longer than 12 months. Accordingly, the Company reclassified restricted cash on its balance sheet from current assets to non-current assets. The amount of restricted cash reclassified for 2013 was $150,000.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions, and other events and circumstances from non-owner sources. For the year ended December 31, 2013, net loss equaled comprehensive loss. In 2014, the Company had short-term investments which included unrealized gains and losses which were reported in other comprehensive loss.

Net Loss per Common Share Attributable to Common Shareholders

Basic net loss per share attributable to common shareholders is calculated by dividing the net loss attributable to common shareholders by the weighted-average number of common shares outstanding during the period without consideration for common stock equivalents. Diluted net loss per share of common stock is the same as basic net loss per share of common stock, since the effects of potentially dilutive securities are antidilutive. The net loss per share of common stock attributable to common shareholders was computed using the two-class method required for participating securities. All series of our convertible preferred stock were considered to be participating securities as they were entitled to participate in undistributed earnings with shares of common stock. Due to our net loss, there was no impact on the earnings per share calculation in applying the two-class method since the participating securities had no legal requirement to share in any losses.

The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common shareholders for the periods presented as the effect of including such securities would be antidilutive:

Year Ended December 30

2014

2013

2012

Convertible preferred stock – as converted to common stock

—

9,743,762

7,478,998

Warrants to purchase convertible preferred stock – as converted to common stock

—

377,752

Warrants to purchase common stock

—

374,210

445,546

Options to purchase common stock

4,732,564

3,286,870

1,522,304

4,732,564

13,782,594

9,824,600

New Accounting Pronouncements

In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers. ASU 2014-09 is effective for annual periods beginning after December 15, 2016 and interim periods within those annual periods. The revenue standard’s core principle is built on the contract between a vendor and a customer for the provision of goods and services. It attempts to depict the exchange of rights and obligations between the parties in the pattern of revenue recognition based on the consideration to which the vendor is entitled. To accomplish this objective, the standard requires five basic steps: (1) identify the contract with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, (5) recognize revenue when (or as) the entity satisfies a performance obligation. Management is currently evaluating the effect the adoption of this standard will have on our financial statements.

In June 2014, FASB issued ASU 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. The amendments in this update require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. A reporting entity should apply existing guidance in ASC 718, Compensation—Stock Compensation, as it relates to awards with performance conditions that affect vesting to account for such awards. The amendments in this update will be effective for the Company as of January 1, 2016. Earlier adoption is permitted. Entities may apply the amendments in this update either: (1) prospectively to all awards granted or modified after the effective date; or (2) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. If a retrospective transition is adopted, the cumulative effect of applying this update as of the beginning of the earliest annual period presented in the financial statements should be recognized as an adjustment to the opening retained earnings balance at that date. In addition, if a retrospective transition is adopted, an entity may use hindsight in measuring and recognizing the compensation cost. Management is currently assessing the impact of this update, and believes that its adoption on January 1, 2016 will not have a material impact on our consolidated financial statements.

In August 2014, FASB issued ASU 2014-15, Presentation of Financial Statements—Going Concern. The amendments in this update require management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. Specifically, the amendments (1) provide a definition of the term substantial doubt, (2) require an evaluation every reporting period, including interim periods, (3) provide principles for considering the mitigating effect of management’s plans, (4) require certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans, (5) require an express statement and other disclosures when substantial doubt is not alleviated, and (6) require an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). The amendments in this update are effective for us as of January 1, 2017. Early application is permitted. Management is currently assessing the impact of this update.

Cash_Cash_Equivalents_and_Shor

Cash, Cash Equivalents and Short-Term Investments	12 Months Ended
Cash, Cash Equivalents and Short-Term Investments	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Short-Term Investments	2. Cash, Cash Equivalents and Short-Term Investments

	The following is a summary of cash, cash equivalents and short-term investments as of December 31, 2014 (in thousands):



		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Cash and cash equivalents:
	Cash and money market funds	$	36,534	$	—	$	—		$	36,534
	Corporate bonds		10,869		—		(1	)		10,868

	Total cash and cash equivalents	$	47,403	$	—	$	(1	)	$	47,402

	Short-term investments:
	Corporate bonds	$	42,810	$	—	$	(42	)	$	42,768
	Commercial paper		7,686		13		—			7,699
	Government securities		4,411		—		—			4,411

	Total short-term investments	$	54,907	$	13	$	(42	)	$	54,878


	For the year ended December 31, 2014, there were no realized gains or losses on the available-for-sale securities. All available-for-sale marketable securities held at December 31, 2014 had maturity dates less than one year. Unrealized losses are recognized when a decline in fair value is determined to be other-than-temporary. As of December 31, 2014, no investment was in a continuous unrealized loss position for more than one year, the unrealized losses were not due to changes in credit risk and we believe that it is more likely than not that the investments will be held to maturity or a forecasted recovery of fair value.

Property_and_Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property and Equipment	3. Property and Equipment

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



		December 31,
		2014			2013
	Production equipment	$	6,082		$	2,148
	Office equipment		620			345
	Lab equipment		1,963			1,601
	Leasehold improvements		4,009			890
	Construction in progress		1,850			400

			14,524			5,384
	Less accumulated depreciation		(2,099	)		(759	)

		$	12,425		$	4,625


	Depreciation and amortization expense for the years ended December 31, 2014 and 2013, was $2.1 million and $0.8 million, respectively.

Accrued_Liabilities

Accrued Liabilities	12 Months Ended
Accrued Liabilities	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued Liabilities	4. Accrued Liabilities

	Accrued Liabilities consisted of the following (in thousands):



		December 31,
		2014		2013
	Accrued compensation and Benefits	$	509	$	1,184
	Accrued accounts payable		967		902
	Accrued payroll tax withholding		1,082		—
	Other accruals		467		494

		$	3,025	$	2,580

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2014
Leases [Abstract]
Leases	5. Leases

	In July 2012, the Company entered into a capital lease agreement with GL Filtration, Ltd. to lease production equipment, which was recorded on the Company’s balance sheet at $293,000. The term of the lease is for 24 months, with equal monthly installments in the amount of $13,185. Expense related to the amortization of this asset is included in depreciation expense.

	In August 2012, the Company entered into a lease agreement with the University of North Texas Health Science Center at Fort Worth for the lease of laboratory space within the Health Science Center in Fort Worth, TX. The term of the lease was for 12 months, commencing on August 1, 2012, with the provision that either party may cancel the lease upon providing 30 days’ advance notice. In August 2013, the Company renewed the lease under substantially the same lease terms for an additional 12 months. In August 2014, the Company renewed the lease under substantially the same lease terms for an additional 6 months. This lease was terminated by the Company, effective December 31, 2014, after the Company provided appropriate notice.

	In February 2013, the Company entered into a lease agreement with PW Commerce Center, LP for the lease of 25,682 square feet of space to house the Company’s corporate offices and production facility in Coppell, TX. The term of the lease is for 125 months, commencing on April 15, 2013, with an option to renew the lease for one five-year period at the then-market rate. Under the terms of the lease, rent was abated for the first five months of the lease term and the rent for the sixth month was paid at the time the lease was executed. Thereafter, rent is due and payable on the first day of each month of the lease term. Monthly rent expense under this lease will approximate $12,758 on a straight-line basis.



	In April 2013, the Company entered into a lease agreement with Renault & Handley Oakmead Solar Joint Venture LP for the lease of 1,172 square feet of office space in Menlo Park, CA, for executive use. The term of the lease is for 24 months, commencing on May 1, 2013, with an option to extend the lease for an additional period of 24 months at a rental rate equal to 95% of the then fair market rental value. Rent is due and payable on the first day of each month of the lease term. In October 2014, the Company vacated this space and with appropriate notice terminated the lease effective as of November 30, 2014.

	In October 2013, the Company entered into a sublease agreement with InB: Hauser Pharmaceutical Services, Inc. to sublease 19,415 square feet of production and office space in Denver, CO, for production and research and development purposes. The term of the sublease is for 38.4 months, commencing on October 18, 2013, with an option to extend the lease for an additional period of 36 months at a rental rate equal to the amounts the sublessor is required to pay its landlord. Rent is due and payable on the first day of each month of the lease term. Monthly rent expense under this lease will approximate $15,399 on a straight-line basis. In addition to the sublet space, the Company also received title to certain production, laboratory, and office equipment and furniture located in the facility. The Company utilized a third-party consultant to appraise the fair value of the equipment at the time of the commencement of the lease, and the Company recorded the fair value of the assets and a corresponding lease incentive amount at the lease commencement date. The lease incentive is being amortized over the life of the sublease and the Company recognized $92,000 and $19,000 of amortization in 2014 and 2013, respectively.

	In June 2014, the Company entered into a capital lease agreement with GL Filtration, Ltd. to lease production equipment, which was recorded on its balance sheet at $0.6 million. The term of the lease is for 24 months, with equal monthly installments in the amount of $27,885. Expense related to the amortization of this asset is included in depreciation expense. As of December 31, 2014, accumulated amortization related to this asset totaled $43,000.

	In July 2014, the Company entered into a lease agreement with Harvard Investment Company for the lease of 6,370 square feet of space in Redwood City, CA for executive use. The term of the lease is for 36 months, commencing on September 1, 2014, with an option to extend the lease for one three-year period at the then market rate. Rent is due and payable on the first day of each month of the lease term. Monthly rent expense under this lease will approximate $25,062 on a straight-line basis.

	In October 2014, the Company entered into a one month lease agreement with Regus Management Group, LLC for 9 individual offices in Grapevine, TX commencing November 1, 2014 and a five month lease agreement for 15 individual offices in Grapevine, TX commencing December 1, 2014. Rent is due and payable on the first day of each month of the lease term.

	Minimum annual lease payments under noncancelable lease arrangements at December 31, 2014, are as follows (in thousands):



		Capital		Operating
		Leases		Leases
	Year ending December 31:
	2015	$	335	$	688
	2016		139		649
	2017		—		365
	2018		—		158
	2019		—		163
	Thereafter				627

	Total minimum lease payments		474	$	2,650

	Less amount representing interest		43

	Present value of future minimum lease payments		431
	Less current installments of obligations under capital leases		304

	Long-term capital lease obligations	$	127




	Total rent expense charged to operations under terms of these operating leases was $0.5 million and $0.2 million for the years ended December 31, 2014 and 2013, respectively.

Borrowings

Borrowings	12 Months Ended
Borrowings	Dec. 31, 2014
Debt Disclosure [Abstract]
Borrowings	6. Borrowings
	Convertible Notes
	In November 2011, the Company issued a $3.0 million mandatorily convertible note payable to Devon Park Bioventures, L.P. (Devon Park), with $2.5 million received at closing and $0.5 million received in December 2011. At the same time, the Company issued identical notes payable to 18 other investors and received an additional $1.3 million. One investor immediately converted its $175,000 note into 47,064 shares of Series B Redeemable Preferred Stock. In July 2012, the Company issued an additional identical $1.0 million note payable to Devon Park. The notes were payable at the earlier of (i) the sale of the Company or (ii) the liquidation of the Company and bore interest at the rate of 8.0% simple interest per annum, to be accrued but not payable unless and until the principal was repaid. The notes also included a requirement for mandatory conversion, upon the closing of a future equity financing of at least $15.0 million from new investors, into either Series B Redeemable Preferred Stock or the new equity security issued in the financing transaction. Upon the conversion of the notes, the noteholders were entitled to receive warrants exercisable for shares of the same security into which the notes were converted, at an amount equal to 25% of the shares received upon conversion. In October 2012, the Company consummated its Series C redeemable preferred equity offering, which triggered the mandatory conversion of the notes payable. The notes, plus accrued interest of $0.3 million, were converted into 1,463,937 shares of Series B Redeemable Preferred Stock. At the same time, the Company issued warrants exercisable for 365,986 shares of Series B Redeemable Preferred Stock.
	The contingent repayment feature of the notes was determined to be an embedded derivative to be accounted for separately from the notes payable and subsequently marked to market. Given the unlikelihood of the events requiring repayment, the value of the repayment feature was determined to be inconsequential. The right to receive the warrants was accounted for as warrants issued at the date the notes were issued. The fair value of these warrants was recorded separately from the value of the notes, and the warrants are classified as a liability and are being marked to market each period (see Note 7). The warrants to be received by the note holders upon conversion of the notes into preferred stock resulted in a beneficial conversion feature associated with the notes payable of $1.0 million on the notes issued in November 2011 and $0.3 million on the additional note issued in 2012.
	In connection with the convertible note transactions, the Company received gross proceeds of $5.3 million, which were offset by issuance costs for legal and banking services of $0.5 million. Warrants were also issued to bankers totaling $0.1 million for services provided relating to the convertible note transactions, which were recorded as deferred debt issuance costs, similar to the other legal and banking services paid for in cash. These costs were amortized over the period the notes were outstanding. The fair value of the warrants issued to the noteholders of $1.1 million and the beneficial conversion feature relating to the notes, including accrued interest, of $1.3 million were recorded as discounts to the notes and accreted through interest expense in 2011 and 2012. Amortization of the deferred financing costs and accretion of the discount on the notes to the date the notes were converted, including the effect of the beneficial conversion feature noted above, resulted in a charge recognized in interest expense of $1.8 million for the year ended December 31, 2012 ($0 for each of the years ended December 31, 2014 and 2013).
	Credit Facility
	In July 2014, we entered into a Credit and Security Agreement (Credit Agreement) with MidCap Financial SBIC, LP (MidCap) for a $20 million credit facility, secured by all of our assets, with a negative pledge against our intellectual property. The credit facility is structured in two $10 million tranches, with the first tranche drawn at closing and the second tranche to be drawn after we provide evidence to MidCap of positive primary endpoint results from our ZS004 clinical study, which has occurred, but before its expiration on October 31, 2014. Notes issued under the terms of the Credit Agreement will bear interest at the rate of 7.5% per annum, payable monthly, have principal payable in 36 monthly installments commencing on January 1, 2016 and are subject to a $50,000 fee payable to MidCap upon closing. On January 1, 2019, the maturity date of the notes, we will owe MidCap an exit fee equal to 6.5% of the amount of notes funded under the Credit Agreement. We issued a note payable to MidCap in the amount of $10 million for the first tranche on July 14, 2014. The 6.5% exit fee is being recognized as additional interest expense over the term of the note.
	In September 2014, we entered into the First Amendment to Credit and Security Agreement, which extended the second tranche commitment termination date from October 31, 2014 to March 31, 2015. Also in September 2014, MidCap assigned $2.5 million of the credit facility to Silicon Valley Bank (SVB).
	The estimated fair value of the MidCap debt is $10.1 million. The fair value was estimated based upon management’s use of an income approach utilizing a present value technique (Level 3 measurement).

Shareholders_Equity_and_Redeem

Shareholders' Equity and Redeemable Preferred Stock	12 Months Ended
Shareholders' Equity and Redeemable Preferred Stock	Dec. 31, 2014
Equity [Abstract]
Shareholders' Equity and Redeemable Preferred Stock	7. Shareholders’ Equity and Redeemable Preferred Stock

	Preferred Stock

	Prior to its IPO, the Company had issued four classes of preferred stock: Series A, Series B, Series C and Series D (collectively, Pre-IPO Preferred Stock), each with a par value of $0.001. The shares of Series A Preferred Stock were issued from February 2009 through July 2010 at an Original Issue Price of $2.05 per share. The shares of Series B Redeemable Preferred Stock were issued from November 2010 through October 2012 at an Original Issue Price of $3.72 per share. The shares of Series C Redeemable Preferred Stock were issued from October 2012 through August 2013 at an Original Issue Price of $6.67 per share. On February 28, 2014 the Company issued 1,858,012 shares of Series D Redeemable Preferred Stock with an Original Issue Price of $13.455 per share, and total proceeds, net of offering costs, of $24.8 million.

	As of December 31, 2013, the Company’s total outstanding convertible Pre-IPO Preferred Stock was as follows (in thousands, except for share and price per share amounts):



	Pre-IPO Preferred Stock	Shares				Shares				Price		Total Proceeds
		Authorized				Issued				Per Share		(Net of Offering
												Costs)
	Series A		1,494,966				582,976			$	2.05	$	1,196
	Series B		6,768,033				2,261,506				3.72		8,371
	Series C		17,692,308				6,899,281				6.67		42,398

												$	51,965


	On June 23, 2014, upon the closing of the IPO and the filing of our Seventh Amended and Restated Certificate of Incorporation, each one of the outstanding shares of Preferred Stock and Redeemable Preferred Stock was converted to a share of common stock, with a total of 11,979,479 shares converted to common stock. In addition, 5,000,000 shares of new Preferred Stock, par value $0.001 per share, were authorized. The voting powers, preferences and other rights of these Preferred Shares will be determined by our Board of Directors prior to their issuance.

	Warrants

	During 2011 and 2012 the Company issued warrants to directors, bankers, and investors that were exercisable into Common Stock or Series B Redeemable Preferred Stock. The Company issued 57,889 warrants to Salem Partners (Salem) for banking services related to the convertible notes transaction entered into in November 2011 (see Note 6). In July 2012, the Company issued 13,447 warrants to Salem for the final tranche of the convertible debt transaction. In October 2012, the Company granted Salem Capital Partners, LLC (Salem Capital) the rights to receive 344,964 warrants for banking services related to the Series C Redeemable Preferred Stock issuance. These warrants were issued to Salem Capital in August 2013. All of the warrants issued to Salem and Salem Capital were exercisable for Common Stock and were recorded at fair value as equity on the Company’s balance sheet. For those warrants issued in connection with the notes payable transaction, the fair value of the warrants was recognized as a debt issuance cost and amortized over the period the notes payable was outstanding. For those warrants issued in connection with the Series C Redeemable Preferred Stock, the warrants were recorded as a reduction of the proceeds received as an equity issuance cost. On November 1, 2013, Salem, exercised all 71,336 of its warrants, which resulted in proceeds of $0.3 million. On May 13, 2014, Salem Capital exercised all 344,964 of its warrants, which resulted in proceeds of $2.3 million.

	In January 2012, the Company issued 29,247 warrants to three non-executive members of its Board of Directors as compensation for their service to the Company as board members. These warrants are exercisable for Common Stock and were recognized as compensation expense in the Company’s statements of operations.

	In November 2011, the Company issued 11,766 warrants to Chigwell Consulting, Inc. (Chigwell) as part of a Series B subscription by Chigwell. These warrants are exercisable for Series B Redeemable Preferred Stock. In October 2012, the Company issued 365,986 warrants to investors in the convertible debt transaction upon the conversion of the notes into Series B Redeemable Preferred Stock. These warrants are exercisable for Series B Redeemable Preferred Stock. Warrants exercisable for Series Redeemable B Preferred Stock are recorded as liabilities, based on the classification of Series B Redeemable Preferred Stock as temporary equity, and as such are marked to market through the income statement. The Company recorded $3.1 million and $1.4 million of other expense for mark-to-market adjustments related to these warrants for the years ended December 31, 2014 and 2013, respectively.

	Below is a summary of the warrants exercisable for Common Stock that were outstanding as of December 31, 2013 and 2014:



	Date	Number of				Exercise Price
	Date	Shares				per Share
	Outstanding as of January 1, 2013		445,546
	Exercised November 1, 2013		(71,336	)		$	3.72

	Outstanding as of December 31, 2013		374,210
	Exercised May 6, 2014		(9,749	)			2.56
	Exercised May 13, 2014		(344,964	)			6.67
	Exercised May 31, 2014		(19,497	)			2.56

	Outstanding as of December 31, 2014		—


	Below is a summary of the warrants exercisable for Series B Redeemable Preferred Stock that were outstanding as of December 31, 2013 and 2014:



	Date	Expiration		Number of				Exercise Price
	Date	Date		Shares				per Share
	Outstanding as of January 1, 2013 and 2014				377,752
	Exercised May 31, 2014				(340,772	)		$	3.72
	Exercised June 5, 2014				(36,980	)			3.72

					—


	Common Stock

	At inception, the Company entered into an agreement with the founders to issue shares of restricted Common Stock, which had a two-year vesting period for services that would be provided to the Company. Under the terms of the agreement, the Company has the right, but not the obligation, to repurchase the shares of Common Stock at the original purchase price, $0.03 per share, if the holders of the restricted common shares do not meet certain service conditions. In November 2008, the Company issued 779,919 shares of restricted Common Stock to the founders. In November 2009, the Company exercised its right to repurchase 103,663 shares of unvested restricted stock from certain non-employee founders who were no longer providing services to the Company. The Company repurchased these shares at $0.03 per share.

In November 2008, the Company also issued 779,919 shares of Common Stock to HemoCleanse, Inc. in exchange for a sublicense of certain intellectual property rights held by HemoCleanse, Inc., valued at $20,000, or $0.03 per share (see Note 9 below).

As of December 31, 2014, the Company has authorized the issuance of 250,000,000 shares of Common Stock.

Voting Rights

On any matter presented to the shareholders of the Company for their action at any duly authorized meeting of shareholders of the Company, each holder of outstanding shares of Common Stock will be entitled to case the number of votes equal to the number of whole shares of Common Stock held of record by such holder. Except as provided by law or by the other provisions of the Certificate of Incorporation, holders of Common Stock shall vote together as a single class on all matters.

ShareBased_Compensation

Share-Based Compensation	12 Months Ended
Share-Based Compensation	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	8. Share-Based Compensation

	The Company has an employee stock option plan (the Plan), which authorizes the granting of 3,841,099 shares of Common Stock to employees and directors of the Company, as well as non-employees, and allows the holder of the option to purchase Common Stock at a stated exercise price. The number of shares authorized by the plan may be increased each January 1st following the effective date of the plan by the lesser of: a) 4% of the total number of shares outstanding (on an as-converted basis) on December 31st of the preceding year, less the aggregate number of shares available under the plan as of that date (if the result is negative, then this clause equals zero); b) a number of shares determined by the Board of Directors, or c) 1,169,878 (subject to adjustment for any subdivision or consolidation of outstanding shares of Common Stock, declaration of the dividend payable in shares of Common Stock or other stock split). Options vest according to the terms of the grant, which may be immediate or based on the passage of time or the achievement of specified milestones (which had been achieved by December 31, 2014) and have a term of up to 10 years. Unexercised stock options terminate on the expiration date of the grant. The Company recognizes the stock-based compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period.



	The valuation of the share-based compensation awards is a significant accounting estimate that requires the use of judgment and assumptions that are likely to have a material impact on the financial statements. The fair value of option grants is determined using the Black-Scholes option-pricing model. Expected volatilities utilized in the model are based on implied volatilities from traded stocks of peer companies. Similarly, the dividend yield is based on historical experience and the estimate of future dividend yields. The risk-free interest rate is derived from the U.S. Treasury yield curve in effect at the time of grant. The expected lives of the grants are based on the average period the stock options are expected to remain outstanding. As the Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior, the expected term is calculated as the midpoint between the weighted-average vesting term and the contractual expiration periods also known as the simplified method. The Company assumed no awards would be forfeited during the vesting period, as actual forfeitures have been minimal through December 31, 2014, and the remaining weighted-average vesting term for nonvested options is for a relatively brief time (less than two years). The fair value of the option grants have been estimated, with the following weighted-average assumptions:



		Stock Options
		Year Ended				Year Ended			Year Ended
		December 31,				December 31,			December 31,
		2014				2013			2012
	Expected dividend yield		—	%			—	%		—	%
	Risk-free interest rate		2.13	%			1.87	%		1.84	%
	Volatility		96.9	%			102.2	%		95.9	%
	Expected life		6.45 years				7 years			5 years

	The Company’s stock option activity and related information are summarized as follows:



		Outstanding Options
		Number of				Weighted-			Weighted-
		Shares				Average			Average
						Exercise Price			Remaining
									Contractual Life
									in Years
	Options outstanding at December 31, 2011		183,281			$	1.03			7.75
	Options granted		1,358,520				2.08			9.39
	Options exercised		(19,498	)			1.03			7.97

	Options outstanding at December 31, 2012		1,522,304				1.95			9.1
	Options granted		1,764,566				2.13			9.34

	Options outstanding at December 31, 2013		3,286,870				2.05			8.77
	Options granted		1,525,135				19			9.41
	Options exercised		(79,441	)			1.98			7.16

	Options outstanding at December 31, 2014		4,732,564			$	7.52			8.31

	Exercisable at December 31, 2014		1,668,413			$	2.07			7.47


	The aggregate intrinsic value of options exercised in the twelve months ended December 31, 2014 was $2.4 million. The aggregate intrinsic value of options exercisable as of December 31, 2014, was $65.9 million. The Company will issue new shares of Common Stock upon the exercise of vested options.



	The following is a rollforward of the Company’s nonvested stock options for 2014:



		Options				Weighted-
						Average Grant
						Date Fair Value
	Nonvested stock options at December 31, 2011		26,517			$	0.56
	Granted during the year		1,358,520				1.62
	Vested during the year		(183,962	)			1.36
	Exercised or forfeited during the year		—				—

	Nonvested stock options at December 31, 2012		1,201,075				1.64
	Granted during the year		1,764,566				2.05
	Vested during the year		(393,144	)			1.62
Forfeited during the year		—				—

Nonvested stock options at December 31, 2013		2,572,497				1.92
Granted during the year		1,525,135				15.31
Vested during the year		(1,033,481	)			2.07
Forfeited during the year		—				—

Nonvested stock options at December 31, 2014		3,064,151			$	7.45


The weighted-average grant date fair value of options granted in the year ended December 31, 2014, is $15.31. Vesting terms for certain employee grant agreements did not initially match the terms approved by the Company’s Board of Directors for 2,017,650 of the options reflected as granted in 2012 and 2013 in the tables above. Accordingly, these options were not considered granted for accounting purposes until a mutual understanding of the terms was obtained through amendment of the grant agreements on January 10, 2014. Certain of these options were considered to have service inception dates in 2013, which resulted in the vested portion of these options being remeasured throughout 2013. Share-based compensation expense of $1.9 million was recorded for the vested portion of these options for the year ended December 31, 2013.

At December 31, 2014, total compensation cost related to nonvested awards not yet recognized was $25.4 million, and the weighted-average period over which this amount is expected to be recognized was 2.74 years. This amount includes the fair value of the unvested portion of those awards that did not have an accounting grant date until January 10, 2014 based on fair value of those options at December 31, 2013.

License_Agreement

License Agreement	12 Months Ended
License Agreement	Dec. 31, 2014
Text Block [Abstract]
License Agreement	9. License Agreement
License Agreement	In July 2008, the Company entered into a sublicense agreement with HemoCleanse, Inc. (HemoCleanse) for an exclusive worldwide license under certain patent rights held by HemoCleanse for the zirconium silicate compound that HemoCleanse had licensed from UOP, LLC (UOP). In exchange for the sublicense rights, the Company issued 779,919 shares of Common Stock to HemoCleanse, Inc. (see Note 7). The sublicense allowed the Company to research, develop, and commercialize the zirconium silicate compound within specified therapeutic fields and to practice certain licensed processes with those therapeutic fields. In December 2011, the Company entered into a license restructuring agreement with HemoCleanse and UOP that terminated the license and sublicense agreements between the parties and created a license agreement between the Company and UOP, whereby the Company received the same exclusive worldwide rights directly from UOP, and a sublicense agreement between the Company and HemoCleanse, whereby HemoCleanse received an exclusive sublicense from the Company for a specified subfield of the UOP rights. The license agreement with UOP expires when the UOP patent rights expire. Under the terms of the license agreement, the Company will pay to UOP a 5% royalty on the Company’s net sales subject to a minimum annual royalty. Total royalty expense charged to operations under terms of these licensing agreements was $100,000 for each of the years ended December 31, 2014 and 2013. As of December 31, 2014, there was an outstanding balance payable to UOP of $100,000 related to these agreements. The Company has received no royalty income under the sublicensing agreement with HemoCleanse since the inception of the sublicense agreement with HemoCleanse.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes
	The Company did not recognize tax expense during 2014, 2013 or 2012. The reconciliation between U.S. federal income taxes at the statutory rate and the Company’s income tax expense for the year is as follows (in thousands):


		Year Ended			Year Ended			Year Ended
		December 31, 2014			December 31, 2013			December 31, 2012
	U.S. tax benefit at statutory rate	$	(21,785	)	$	(11,423	)	$	(3,495	)
	U.S. state income tax		(303	)		(383	)		(105	)
	State effective rate changes		333			—			—
	Permanent differences		1,044			541			748
	Deferred tax valuation allowances		22,097			12,758			2,848
	Research and development credit		(1,885	)		(1,073	)		—
	Other		499			(420	)		4

	Income tax expense	$	—		$	—		$	—

	Net deferred tax assets and liabilities consisted of the following at December 31 (in thousands):


		2014			2013			2012
	Deferred income tax assets:
	Net operating loss carryforwards	$	31,224		$	14,325		$	4,519
	Research and development credit carryforwards		5,196			2,403			114
	Stock compensation		3,425			860			160
	Other		190			52			—

	Total deferred tax assets		40,035			17,640			4,793
	Valuation allowance		(39,554	)		(17,457	)		(4,718	)

	Total deferred tax assets, net		481			183			75
	Deferred income tax liabilities:
	Depreciation and amortization		(481	)		(183	)		(75	)

	Total deferred tax assets, net	$	—			—			—

	Income taxes are computed using the asset and liability method and current income taxes are recorded based on amounts refundable or payable in the current year. Deferred income taxes are recorded based on the estimated future tax effects of loss carryforwards and temporary differences between financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates that are expected to apply to taxable income in the years in which we expect those carryforwards and temporary differences to be recovered or settled. Management regularly evaluates the future realization of deferred tax assets and provides a valuation allowance, if considered necessary, based on such evaluation. As part of the evaluation, management has evaluated taxable income in carryback years, future reversals of taxable temporary differences, feasible tax planning strategies, and future expectations of income. Based upon this evaluation, as of December 31, 2014, the company has recorded a valuation allowance of $39.6 million to reduce the Company’s net deferred tax assets to the amount that is more likely than not to be realized. In 2014, the total valuation allowance increased by $22.1 million primarily due to the increase in net operating loss and federal credit carryforwards which the Company does not believe are more likely than not to be utilized.
	As of December 31, 2014, the Company has federal and state income tax net operating loss (NOL) carryforwards, net of the 382 limitation discussed below, of approximately $93.7 million and $0.5 million, respectively, and federal research tax credit carryforwards, net of the 382 limitation discussed below, of approximately $5.2 million. Additionally, the Company has a Federal NOL carryforward of $3.3 million related to the excess tax benefits associated with stock-based compensation and stock option exercises. The benefit of this NOL will be recognized as an increase to the additional paid-in capital at the point when such NOL provides cash benefit to the Company.

	The NOL carryforwards and research tax credit carryforwards begin to expire in 2029. The Company has experienced multiple changes in ownership as defined under Internal Revenue Code Section 382, prior to the year ending December 31, 2014. The ownership changes have subjected our net operating loss carryforwards and federal research tax credit carryforwards to an annual limitation. In general, the annual use limitation equals the aggregate value of our stock at the time of the ownership change multiplied by a specified tax-exempt interest rate. We estimate the ownership changes will result in $1.5 million of net operating loss carryforwards expiring unused and $0.1 million of federal research tax credit carryforwards expiring unused. Such unusable net operating loss carryforwards and federal tax credit carryforwards are therefore not included in the amount disclosed in the paragraph above.
	The Company had no accrued income taxes payable at December 31, 2014. The federal and state income tax returns of the Company for 2014 are subject to examination by the taxing authority, generally for a period of three years for federal and four years for states from the date the tax returns were filed.
	The Company recognizes uncertain tax positions when it is more-likely-than-not, based on the technical merits, that the position will not be sustained upon examination. At December 31, 2014 and 2013, the Company had no uncertain tax positions.

Defined_Contribution_Plan

Defined Contribution Plan	12 Months Ended
Defined Contribution Plan	Dec. 31, 2014
Postemployment Benefits [Abstract]
Defined Contribution Plan	11. Defined Contribution Plan

	In March, 2014, we began to sponsor a 401(k) retirement plan, in which substantially all of our full-time employees are eligible to participate. Eligible participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. Irrespective of the amount of any participant contributions in a plan year, we will contribute an amount equal to 3% of each participant’s annual salary into their account in the plan each plan year, subject to federal limits per employee for safe harbor plans such as the plan we have offered. For the year ended December 31, 2014, we made safe harbor contributions into the plan totaling $0.2 million.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies

	Commitments

	We have various manufacturing, clinical, research and other contracts with vendors in the conduct of the normal course of business. As of December 31, 2014, we had purchase commitments for approximately $1.5 million with contract manufacturers to produce clinical materials and $1.3 million with equipment vendors for the manufacture of equipment to produce our product. All other significant contracts as of December 31, 2014 were terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, we would only be obligated for the product or services that we had received at the time the termination became effective.

	Contingencies

	While there are no legal proceedings we are aware of, we may become party to various claims and complaints arising from the ordinary course of business. We do not believe that any ultimate liability resulting from any such claims will have a material adverse effect on our results of operations, financial position or liquidity.

Subsequent_Events

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events

	Management has evaluated subsequent events through March 13, 2015, the date that the financial statements were available to be issued.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (unaudited)	12 Months Ended
Selected Quarterly Financial Data (unaudited)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	14. Selected Quarterly Financial Data (unaudited)
	The following table contains quarterly financial information for 2014 and 2013. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period.


			Quarter Ended
			(In Thousands, Except Share and per Share amounts)
			December 31,			September 30,			June 30,			March 31,			December 31,			September 30,			June 30,			March 31,
			2014			2014			2014			2014			2013			2013			2013			2013
	Costs and expenses:
	Research and development(1)		$	14,574		$	12,541		$	11,649		$	6,854		$	6,880		$	7,138		$	6,335		$	4,409
	General and administrative(2)			5,535			4,081			2,881			2,422			3,521			2,224			972			715

	Total costs and expenses			20,109			16,622			14,530			9,276			10,401			9,362			7,307			5,124

	Loss from operations			(20,109	)		(16,622	)		(14,530	)		(9,276	)		(10,401	)		(9,362	)		(7,307	)		(5,124	)
	Other (income) expense:
	Interest/other income(3)			(43	)		(31	)		(11	)		(9	)		(5	)		(5	)		(8	)		(12	)
	Interest expense(4)			249			272			6			3			(4	)		3			5			5
	Expense to mark warrants to market			—			—			1,774			1,297			1,272			32			11			109

	Net loss		$	(20,315	)	$	(16,863	)	$	(16,299	)	$	(10,567	)	$	(11,664	)	$	(9,392	)	$	(7,315	)	$	(5,226	)

	Preferred Stock Accretion			—			—			(129	)		(181	)		(174	)		(173	)		(172	)		(170	)
	Net loss attributable to common shareholders		$	(20,315	)	$	(16,863	)	$	(16,428	)	$	(10,748	)	$	(11,838	)	$	(9,565	)	$	(7,487	)	$	(5,396	)

	Net loss per share attributable to common shareholders, basic and diluted		$	(0.98	)	$	(0.81	)	$	(4.72	)	$	(6.60	)	$	(7.38	)	$	(6.14	)	$	(4.81	)	$	(3.46	)

	Weighted-average common shares used to compute net loss per share attributable to common shareholders, basic and diluted			20,832,475			20,818,794			3,482,340			1,628,976			1,604,490			1,557,643			1,557,643			1,557,643


	-1	Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.
	-2	Administrative expenses in the quarter ended December 31, 2013 include $650 of additional legal and professional fees, incurred primarily in support of our product development, $219 of additional consulting fees in support of medical communications and $174 of additional non-cash option expense to mark to market certain stock options recorded as liabilities.
	-3	Interest income in the quarters ended September 30, 2014 and December 31, 2014 include interest income on invested surplus cash.
	-4	Interest expense in the quarters ended September 30, 2014 and December 31, 2014 include interest expense related to the MidCap Credit Facility initiated in July 2014 (see note 6 above).

Nature_of_Business_and_Summary1

Nature of Business and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Description of Organization

Basis of Presentation Including Liquidity

Reverse Stock Split

Cash, Cash Equivalents and Short-Term Investments

Restricted Cash

Property and Equipment

Production equipment

7 years

Office equipment

3–8 years

Lab equipment

3–8 years

Impairment of Long-Lived Assets

Licenses and Patents

Research and Development Expenses

Redeemable Preferred Stock Warrant Liability

Fair Value Measurements

•

Level 1 – quoted prices in active markets for identical assets and liabilities;

•

Level 2 – inputs other than Level 1 quoted prices that are directly or indirectly observable; and

•

Level 3 – unobservable inputs that are not corroborated by market data.

Financial assets and liabilities that have recurring fair value measurements are shown below as of December 31 (in thousands):

Fair Value Measurements at

December 31, 2014 Using

Quoted Prices in

Significant

Active Markets

Other

Unobservable

for

Observable

Inputs

Identical

Inputs

Assets

Description

Total

Level 1

Level 2

Level 3

Financial Assets:

Corporate Bonds

42,768

—

42,768

—

Commercial Paper

7,699

—

7,699

—

Government Securities

4,411

—

4,411

—

Total financial assets

54,878

—

54,878

—

Fair Value Measurements at

December 31, 2013 Using

Quoted Prices in

Significant

Active Markets

Other

Unobservable

for

Observable

Inputs

Identical

Inputs

Assets

Description

Total

Level 1

Level 2

Level 3

Financial liabilities:

Series B Redeemable Preferred Stock warrants

2,667

—

2,667

Total financial liabilities

2,667

—

2,667

Balance as of December 31, 2011

968

Issuance of redeemable preferred stock warrants

213

Net increase in fair value included in other (income) expense

Balance as of December 31, 2012

1,243

Net increase in fair value included in other (income) expense

1,424

Balance as of December 31, 2013

2,667

Net increase in fair value

3,071

Amount reclassified to shareholders’ equity upon exercise

(5,738

)

Balance as of December 31, 2014

—

Share-Based Compensation

Income Taxes

Use of Estimates

Reclassifications

Comprehensive Loss

Net Loss per Common Share Attributable to Common Shareholders

Year Ended December 30

2014

2013

2012

Convertible preferred stock – as converted to common stock

—

9,743,762

7,478,998

Warrants to purchase convertible preferred stock – as converted to common stock

—

377,752

Warrants to purchase common stock

—

374,210

445,546

Options to purchase common stock

4,732,564

3,286,870

1,522,304

4,732,564

13,782,594

9,824,600

New Accounting Pronouncements

Nature_of_Business_and_Summary2

Nature of Business and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Property and Equipment Useful Life	The useful lives of property and equipment are as follows:


	Production equipment		7 years
	Office equipment		3–8 years
	Lab equipment		3–8 years
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	Financial assets and liabilities that have recurring fair value measurements are shown below as of December 31 (in thousands):



					Fair Value Measurements at
					December 31, 2014 Using
					Quoted Prices in		Significant		Significant
					Active Markets		Other		Unobservable
					for		Observable		Inputs
					Identical		Inputs
					Assets
	Description	Total			Level 1		Level 2		Level 3
	Financial Assets:
	Corporate Bonds	$	42,768		$	—	$	42,768	$	—
	Commercial Paper		7,699			—		7,699		—
	Government Securities		4,411			—		4,411		—

	Total financial assets	$	54,878		$	—	$	54,878	$	—




					Fair Value Measurements at
					December 31, 2013 Using
					Quoted Prices in		Significant		Significant
					Active Markets		Other		Unobservable
					for		Observable		Inputs
					Identical		Inputs
					Assets
	Description	Total			Level 1		Level 2		Level 3
	Financial liabilities:
	Series B Redeemable Preferred Stock warrants	$	2,667		$	—	$	—	$	2,667

	Total financial liabilities	$	2,667		$	—	$	—	$	2,667

Summary of Changes in Estimated Fair Value of Redeemable Preferred Stock Warrants	The following table sets forth a summary of the changes in the estimated fair value of the Company’s redeemable preferred stock warrants, which were measured at fair value on a recurring basis since inception (in thousands):



	Balance as of December 31, 2011	$	968
	Issuance of redeemable preferred stock warrants		213
	Net increase in fair value included in other (income) expense		62

	Balance as of December 31, 2012		1,243
	Net increase in fair value included in other (income) expense		1,424

	Balance as of December 31, 2013	$	2,667
	Net increase in fair value		3,071
	Amount reclassified to shareholders’ equity upon exercise		(5,738	)

	Balance as of December 31, 2014	$	—

Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Common Share	The following outstanding shares of common stock equivalents were excluded from the computations of diluted net loss per common share attributable to common shareholders for the periods presented as the effect of including such securities would be antidilutive:



		Year Ended December 30
		2014			2013		2012
	Convertible preferred stock – as converted to common stock		—			9,743,762		7,478,998
	Warrants to purchase convertible preferred stock – as converted to common stock		—			377,752		377,752
	Warrants to purchase common stock		—			374,210		445,546
	Options to purchase common stock		4,732,564			3,286,870		1,522,304

			4,732,564			13,782,594		9,824,600

Cash_Cash_Equivalents_and_Shor1

Cash, Cash Equivalents and Short-Term Investments (Tables)	12 Months Ended
Cash, Cash Equivalents and Short-Term Investments (Tables)	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Summary of Cash, Cash Equivalents and Short-Term Investments	The following is a summary of cash, cash equivalents and short-term investments as of December 31, 2014 (in thousands):



		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Cash and cash equivalents:
	Cash and money market funds	$	36,534	$	—	$	—		$	36,534
	Corporate bonds		10,869		—		(1	)		10,868

	Total cash and cash equivalents	$	47,403	$	—	$	(1	)	$	47,402

	Short-term investments:
	Corporate bonds	$	42,810	$	—	$	(42	)	$	42,768
	Commercial paper		7,686		13		—			7,699
	Government securities		4,411		—		—			4,411

	Total short-term investments	$	54,907	$	13	$	(42	)	$	54,878

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consisted of the following (in thousands):



		December 31,
		2014			2013
	Production equipment	$	6,082		$	2,148
	Office equipment		620			345
	Lab equipment		1,963			1,601
	Leasehold improvements		4,009			890
	Construction in progress		1,850			400

			14,524			5,384
	Less accumulated depreciation		(2,099	)		(759	)

		$	12,425		$	4,625

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	12 Months Ended
Accrued Liabilities (Tables)	Dec. 31, 2014
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued Liabilities consisted of the following (in thousands):



		December 31,
		2014		2013
	Accrued compensation and Benefits	$	509	$	1,184
	Accrued accounts payable		967		902
	Accrued payroll tax withholding		1,082		—
	Other accruals		467		494

		$	3,025	$	2,580

Leases_Tables

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2014
Leases [Abstract]
Minimum Annual Lease Payments Under Noncancelable Lease Arrangements	Minimum annual lease payments under noncancelable lease arrangements at December 31, 2014, are as follows (in thousands):



		Capital		Operating
		Leases		Leases
	Year ending December 31:
	2015	$	335	$	688
	2016		139		649
	2017		—		365
	2018		—		158
	2019		—		163
	Thereafter				627

	Total minimum lease payments		474	$	2,650

	Less amount representing interest		43

	Present value of future minimum lease payments		431
	Less current installments of obligations under capital leases		304

	Long-term capital lease obligations	$	127

Shareholders_Equity_and_Redeem1

Shareholders' Equity and Redeemable Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Total Outstanding Convertible Preferred Stock	As of December 31, 2013, the Company’s total outstanding convertible Pre-IPO Preferred Stock was as follows (in thousands, except for share and price per share amounts):



	Pre-IPO Preferred Stock	Shares				Shares				Price		Total Proceeds
		Authorized				Issued				Per Share		(Net of Offering
												Costs)
	Series A		1,494,966				582,976			$	2.05	$	1,196
	Series B		6,768,033				2,261,506				3.72		8,371
	Series C		17,692,308				6,899,281				6.67		42,398

												$	51,965

Common Stock [Member]
Summary of Warrants Exercisable	Below is a summary of the warrants exercisable for Common Stock that were outstanding as of December 31, 2013 and 2014:



	Date	Number of				Exercise Price
	Date	Shares				per Share
	Outstanding as of January 1, 2013		445,546
	Exercised November 1, 2013		(71,336	)		$	3.72

	Outstanding as of December 31, 2013		374,210
	Exercised May 6, 2014		(9,749	)			2.56
	Exercised May 13, 2014		(344,964	)			6.67
	Exercised May 31, 2014		(19,497	)			2.56

	Outstanding as of December 31, 2014		—

Series B Preferred Stock [Member]
Summary of Warrants Exercisable	Below is a summary of the warrants exercisable for Series B Redeemable Preferred Stock that were outstanding as of December 31, 2013 and 2014:



	Date	Expiration		Number of				Exercise Price
	Date	Date		Shares				per Share
	Outstanding as of January 1, 2013 and 2014				377,752
	Exercised May 31, 2014				(340,772	)		$	3.72
	Exercised June 5, 2014				(36,980	)			3.72

					—

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	12 Months Ended
Share-Based Compensation (Tables)	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted Average Assumptions Used to Fair Value of Options Granted	The fair value of the option grants have been estimated, with the following weighted-average assumptions:



		Stock Options
		Year Ended			Year Ended			Year Ended
		December 31,			December 31,			December 31,
		2014			2013			2012
	Expected dividend yield		—	%		—	%		—	%
	Risk-free interest rate		2.13	%		1.87	%		1.84	%
	Volatility		96.9	%		102.2	%		95.9	%
	Expected life		6.45 years			7 years			5 years
Summary of Stock Option Activity	The Company’s stock option activity and related information are summarized as follows:



		Outstanding Options
		Number of			Weighted-			Weighted-
		Shares			Average			Average
					Exercise Price			Remaining
								Contractual Life
								in Years
	Options outstanding at December 31, 2011		183,281		$	1.03			7.75
	Options granted		1,358,520			2.08			9.39
	Options exercised		(19,498	)		1.03			7.97

	Options outstanding at December 31, 2012		1,522,304			1.95			9.1
	Options granted		1,764,566			2.13			9.34

	Options outstanding at December 31, 2013		3,286,870			2.05			8.77
	Options granted		1,525,135			19			9.41
	Options exercised		(79,441	)		1.98			7.16

	Options outstanding at December 31, 2014		4,732,564		$	7.52			8.31

	Exercisable at December 31, 2014		1,668,413		$	2.07			7.47

Nonvested Stock Options	The following is a rollforward of the Company’s nonvested stock options for 2014:


		Options			Weighted-
					Average Grant
					Date Fair Value
	Nonvested stock options at December 31, 2011		26,517		$	0.56
	Granted during the year		1,358,520			1.62
	Vested during the year		(183,962	)		1.36
	Exercised or forfeited during the year		—			—

	Nonvested stock options at December 31, 2012		1,201,075			1.64
	Granted during the year		1,764,566			2.05
	Vested during the year		(393,144	)		1.62
	Forfeited during the year		—			—

	Nonvested stock options at December 31, 2013		2,572,497			1.92
	Granted during the year		1,525,135			15.31
	Vested during the year		(1,033,481	)		2.07
	Forfeited during the year		—			—

	Nonvested stock options at December 31, 2014		3,064,151		$	7.45

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense Reconciliation	The reconciliation between U.S. federal income taxes at the statutory rate and the Company’s income tax expense for the year is as follows (in thousands):



		Year Ended			Year Ended			Year Ended
		December 31, 2014			December 31, 2013			December 31, 2012
	U.S. tax benefit at statutory rate	$	(21,785	)	$	(11,423	)	$	(3,495	)
	U.S. state income tax		(303	)		(383	)		(105	)
	State effective rate changes		333			—			—
	Permanent differences		1,044			541			748
	Deferred tax valuation allowances		22,097			12,758			2,848
	Research and development credit		(1,885	)		(1,073	)		—
	Other		499			(420	)		4

	Income tax expense	$	—		$	—		$	—

Net Deferred Tax Assets and Liabilities	Net deferred tax assets and liabilities consisted of the following at December 31 (in thousands):



		2014			2013			2012
	Deferred income tax assets:
	Net operating loss carryforwards	$	31,224		$	14,325		$	4,519
	Research and development credit carryforwards		5,196			2,403			114
	Stock compensation		3,425			860			160
	Other		190			52			—

	Total deferred tax assets		40,035			17,640			4,793
	Valuation allowance		(39,554	)		(17,457	)		(4,718	)

	Total deferred tax assets, net		481			183			75
	Deferred income tax liabilities:
	Depreciation and amortization		(481	)		(183	)		(75	)

	Total deferred tax assets, net	$	—			—			—

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
Selected Quarterly Financial Data (unaudited) (Tables)	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Data	The following table contains quarterly financial information for 2014 and 2013. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period.


			Quarter Ended
			(In Thousands, Except Share and per Share amounts)
			December 31,			September 30,			June 30,			March 31,			December 31,			September 30,			June 30,			March 31,
			2014			2014			2014			2014			2013			2013			2013			2013
	Costs and expenses:
	Research and development(1)		$	14,574		$	12,541		$	11,649		$	6,854		$	6,880		$	7,138		$	6,335		$	4,409
	General and administrative(2)			5,535			4,081			2,881			2,422			3,521			2,224			972			715

	Total costs and expenses			20,109			16,622			14,530			9,276			10,401			9,362			7,307			5,124

	Loss from operations			(20,109	)		(16,622	)		(14,530	)		(9,276	)		(10,401	)		(9,362	)		(7,307	)		(5,124	)
	Other (income) expense:
	Interest/other income(3)			(43	)		(31	)		(11	)		(9	)		(5	)		(5	)		(8	)		(12	)
	Interest expense(4)			249			272			6			3			(4	)		3			5			5
	Expense to mark warrants to market			—			—			1,774			1,297			1,272			32			11			109

	Net loss		$	(20,315	)	$	(16,863	)	$	(16,299	)	$	(10,567	)	$	(11,664	)	$	(9,392	)	$	(7,315	)	$	(5,226	)

	Preferred Stock Accretion			—			—			(129	)		(181	)		(174	)		(173	)		(172	)		(170	)
	Net loss attributable to common shareholders		$	(20,315	)	$	(16,863	)	$	(16,428	)	$	(10,748	)	$	(11,838	)	$	(9,565	)	$	(7,487	)	$	(5,396	)

	Net loss per share attributable to common shareholders, basic and diluted		$	(0.98	)	$	(0.81	)	$	(4.72	)	$	(6.60	)	$	(7.38	)	$	(6.14	)	$	(4.81	)	$	(3.46	)

	Weighted-average common shares used to compute net loss per share attributable to common shareholders, basic and diluted			20,832,475			20,818,794			3,482,340			1,628,976			1,604,490			1,557,643			1,557,643			1,557,643


	-1	Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.
	-2	Administrative expenses in the quarter ended December 31, 2013 include $650 of additional legal and professional fees, incurred primarily in support of our product development, $219 of additional consulting fees in support of medical communications and $174 of additional non-cash option expense to mark to market certain stock options recorded as liabilities.
	-3	Interest income in the quarters ended September 30, 2014 and December 31, 2014 include interest income on invested surplus cash.
	-4	Interest expense in the quarters ended September 30, 2014 and December 31, 2014 include interest expense related to the MidCap Credit Facility initiated in July 2014 (see note 6 above).

Nature_of_Business_and_Summary3

Nature of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended		3 Months Ended																12 Months Ended			36 Months Ended
	Jun. 23, 2014	Aug. 31, 2014	Jun. 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	Dec. 31, 2010	Nov. 30, 2008	Jul. 31, 2014
Restricted Cash and Investments [Line Items]
Common stock price per share																								$0.03
Common stock, shares outstanding				20,898,212								1,628,997								20,898,212	1,628,997
Common stock, shares issued				20,898,212								1,628,997								20,898,212	1,628,997
Proceeds from issue of common stock																				$112,117,000
Payments for underwriting discounts and commissions	8,600,000
Net Proceeds from public offering	112,100,000
Convertible preferred stock outstanding				0		0						0								0	0
Common stock, shares authorized	250,000,000			250,000,000								49,574,865								250,000,000	49,574,865
Preferred stock, shares authorized	5,000,000			5,000,000																5,000,000
Common stock, par value	$0.00			$0.00								$0.00								$0.00	$0.00
Preferred stock, par value	$0.00			$0.00								$0.00								$0.00	$0.00
Cash, cash equivalents and short term investments				102,300,000																102,300,000
Accumulated deficit				-114,278,000								-50,234,000								-114,278,000	-50,234,000
Reverse Stock Split, Ratio			2.56437
Maturity date of marketable securities																				Marketable securities with maturities greater than 90 days at the date of purchase and 12 months or less remaining at the balance sheet date will be classified as short-term
Restricted cash to support credit limit				301,000								150,000								301,000	150,000
Increase in restricted cash		150,000																		-151,000	-150,000
Impairment charges																				0
Share-based compensation expenses																				7,668,000	2,142,000	233,000
Cumulative restricted stock compensation expense																							69,976
Reclassification of medical affairs expenses				14,574,000	[1]	12,541,000	[1]	11,649,000	[1]	6,854,000	[1]	6,880,000	[1]	7,138,000	[1]	6,335,000	[1]	4,409,000	[1]	45,618,000	24,762,000	6,989,000
Amount of restricted cash reclassified												150,000									150,000
Non Employee Stock Option [Member]
Restricted Cash and Investments [Line Items]
Share-based compensation expenses																					200,000
Federal [Member]
Restricted Cash and Investments [Line Items]
Net operating loss carryforwards				93,700,000																93,700,000
Federal [Member] \| Research Tax Credit Carryforward [Member]
Restricted Cash and Investments [Line Items]
Tax credit carryforwards				5,200,000																5,200,000
MidCap Financial SBIC, LP [Member]
Restricted Cash and Investments [Line Items]
Amount of credit facility				10,000,000																10,000,000					10,000,000
Medical Affairs [Member]
Restricted Cash and Investments [Line Items]
Reclassification of medical affairs expenses						1,618,000		1,673,000		595,000		254,000									254,000	0
Maximum [Member]
Restricted Cash and Investments [Line Items]
Common stock, shares authorized	255,000,000
Restricted cash to support credit limit		300,000
Minimum [Member]
Restricted Cash and Investments [Line Items]
Restricted cash to support credit limit		150,000
IPO [Member]
Restricted Cash and Investments [Line Items]
Common stock price per share	$18
Common stock, shares outstanding	6,836,111
Proceeds from issue of common stock	114,400,000
Public offering expenses	$2,300,000																			$10,900,000
IPO [Member] \| Convertible Preferred Stock [Member]
Restricted Cash and Investments [Line Items]
Convertible preferred stock outstanding	11,979,479
Underwriter [Member]
Restricted Cash and Investments [Line Items]
Common stock, shares issued	891,667

[1]	(1) Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.

Nature_of_Business_and_Summary4

Nature of Business and Summary of Significant Accounting Policies - Property and Equipment Useful Life (Detail)	12 Months Ended
	Dec. 31, 2014
Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	7 years
Minimum [Member] \| Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Minimum [Member] \| Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Maximum [Member] \| Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	8 years
Maximum [Member] \| Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	8 years

Nature_of_Business_and_Summary5

Nature of Business and Summary of Significant Accounting Policies - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (Recurring Fair Value Measurements [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial Assets:
Total financial assets	$54,878
Financial liabilities:
Total financial liabilities		2,667
Significant Other Observable Inputs, Level 2 [Member]
Financial Assets:
Total financial assets	54,878
Significant Unobservable Inputs, Level 3 [Member]
Financial liabilities:
Total financial liabilities		2,667
Series B Preferred Stock [Member]
Financial liabilities:
Series B Redeemable Preferred Stock warrants		2,667
Series B Preferred Stock [Member] \| Significant Unobservable Inputs, Level 3 [Member]
Financial liabilities:
Series B Redeemable Preferred Stock warrants		2,667
Corporate Bonds [Member]
Financial Assets:
Total financial assets	42,768
Corporate Bonds [Member] \| Significant Other Observable Inputs, Level 2 [Member]
Financial Assets:
Total financial assets	42,768
Commercial Paper [Member]
Financial Assets:
Total financial assets	7,699
Commercial Paper [Member] \| Significant Other Observable Inputs, Level 2 [Member]
Financial Assets:
Total financial assets	7,699
Government Securities [Member]
Financial Assets:
Total financial assets	4,411
Government Securities [Member] \| Significant Other Observable Inputs, Level 2 [Member]
Financial Assets:
Total financial assets	$4,411

Nature_of_Business_and_Summary6

Nature of Business and Summary of Significant Accounting Policies - Summary of Changes in Estimated Fair Value of Redeemable Preferred Stock Warrants (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Changes In Fair Value Of Warrant Liability [Abstract]
Beginning balance	$2,667	$1,243	$968
Issuance of redeemable preferred stock warrants			213
Net increase in fair value	3,071	1,424	62
Amount reclassified to shareholders' equity upon exercise	-5,738
Ending balance		$2,667	$1,243

Nature_of_Business_and_Summary7

Nature of Business and Summary of Significant Accounting Policies - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Common Share (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share	4,732,564	13,782,594	9,824,600
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share		9,743,762	7,478,998
Warrants to Purchase Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share		377,752	377,752
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share		374,210	445,546
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share	4,732,564	3,286,870	1,522,304

Cash_Cash_Equivalents_and_Shor2

Cash, Cash Equivalents and Short-Term Investments - Summary of Cash, Cash Equivalents and Short-Term Investments (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified	Dec. 31, 2014
Cash and Cash Equivalents [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	$47,403
Gross Unrealized Losses	-1
Estimated Fair Value	47,402
Cash and Cash Equivalents [Member] \| Cash and Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	36,534
Estimated Fair Value	36,534
Cash and Cash Equivalents [Member] \| Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	10,869
Gross Unrealized Losses	-1
Estimated Fair Value	10,868
Short-term Investments [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	54,907
Gross Unrealized Gains	13
Gross Unrealized Losses	-42
Estimated Fair Value	54,878
Short-term Investments [Member] \| Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	42,810
Gross Unrealized Losses	-42
Estimated Fair Value	42,768
Short-term Investments [Member] \| Commercial Paper [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	7,686
Gross Unrealized Gains	13
Estimated Fair Value	7,699
Short-term Investments [Member] \| Government Securities [Member]
Cash and Cash Equivalents [Line Items]
Amortized Cost	4,411
Estimated Fair Value	$4,411

Cash_Cash_Equivalents_and_Shor3

Cash, Cash Equivalents and Short-Term Investments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Cash and Cash Equivalents [Line Items]
Realized gains or losses on the available-for-sale securities	$0
Continuous unrealized loss position,Amount	$0
Maximum [Member]
Cash and Cash Equivalents [Line Items]
Available-for-sale marketable securities held maturity dates	1 year

Property_and_Equipment_Summary

Property and Equipment - Summary of Property and Equipment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$14,524	$5,384
Less accumulated depreciation	-2,099	-759
Total property and equipment, net	12,425	4,625
Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,082	2,148
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	620	345
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,963	1,601
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,009	890
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$1,850	$400

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property Plant and Equipment Useful Life and Values [Abstract]
Depreciation and amortization expense	$1,340	$705	$49

Accrued_Liabilities_Schedule_o

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Payables and Accruals [Abstract]
Accrued compensation and Benefits	$509	$1,184
Accrued Accounts Payable	967	902
Accrued payroll tax withholding	1,082
Other accruals	467	494
Total Accrued Liabilities	$3,025	$2,580

Leases_Additional_Information_

Leases - Additional Information (Detail) (USD $)

1 Months Ended

12 Months Ended

1 Months Ended

Apr. 30, 2013

Feb. 28, 2013

Jul. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Jul. 31, 2014

Oct. 31, 2014

Aug. 31, 2014

Aug. 31, 2013

Aug. 31, 2012

Oct. 31, 2013

Jun. 30, 2014

sqft

Office

sqft

Lease Rental Expenses [Line Items]

Leased production equipment

$293,000

Capital lease term

24 months

Capital lease monthly payment

13,185

Lease agreement period

24 months

125 months

Lease extension period

24 months

5 years

Rental space

1,172

25,682

Lease rental expense

12,758

500,000

200,000

Rent description

Rent is due and payable on the first day of each month of the lease term.

Amortization of lease incentives

-92,000

-18,000

Accumulated amortization of asset

43,000

Harvard Investment Company [Member]

Lease Rental Expenses [Line Items]

Lease agreement period

36 months

Lease extension period

3 years

Rental space

6,370

Lease rental expense

25,062

Regus Management Group [Member]

Lease Rental Expenses [Line Items]

Lease agreement period

1 month

Number of offices

Grapevine TX [Member]

Lease Rental Expenses [Line Items]

Lease agreement period

5 months

Number of offices

University of North Texas Health Science Center [Member]

Lease Rental Expenses [Line Items]

Lease agreement period

12 months

Lease notice period

30 months

Lease extension period

6 months

12 months

Lease, expiration date

31-Dec-14

Renault & Handley Oakmead Solar Joint Venture [Member]

Lease Rental Expenses [Line Items]

Rent description

Rent is due and payable on the first day of each month of the lease term.

Rental rate

95.00%

Sublease [Member]

Lease Rental Expenses [Line Items]

Lease agreement period

38 years 4 months 24 days

Lease extension period

36 months

Rental space

19,415

Lease rental expense

15,399

Rent description

Rent is due and payable on the first day of each month of the lease term.

Amortization of lease incentives

92,000

19,000

GL Filtration Ltd [Member]

Lease Rental Expenses [Line Items]

Leased production equipment

600,000

Capital lease term

24 months

Capital lease monthly payment

$27,885

Leases_Minimum_Annual_Lease_Pa

Leases - Minimum Annual Lease Payments Under Noncancelable Lease Arrangements (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
2015	$335
2016	139
2017	0
2018	0
2019	0
Thereafter	0
Total minimum lease payments	474
Less amount representing interest	43
Present value of future minimum lease payments	431
Less current installments of obligations under capital leases	304	73
Long-term capital lease obligations	127
Present value of future minimum lease payments	431
2015	688
2016	649
2017	365
2018	158
2019	163
Thereafter	627
Total minimum lease payments	$2,650

Borrowings_Additional_Informat

Borrowings - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended	12 Months Ended			1 Months Ended
Borrowings - Additional Information (Detail) (USD $)	Oct. 31, 2012	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014	Nov. 30, 2011	Dec. 31, 2011	Jul. 31, 2012	Jul. 14, 2014
Debt Instrument [Line Items]
Issuance of convertible note									$1,000,000
Convertible notes, gross proceeds					5,300,000
Number of investors							18,000,000
Convertible notes description			The notes were payable at the earlier of (i) the sale of the Company or (ii) the liquidation of the Company and bore interest at the rate of 8.0% simple interest per annum, to be accrued but not payable unless and until the principal was repaid.
Convertible notes, interest rate			8.00%
Convertible notes conversion terms			The notes also included a requirement for mandatory conversion, upon the closing of a future equity financing of at least $15.0 million from new investors, into either Series B Redeemable Preferred Stock or the new equity security issued in the financing transaction.
Percentage of warrants to be received by note holders			25.00%
Convertible debt, amount of converted note	300,000
Debt issuance costs for legal and banking services			115,000		-24,000
Fair value of warrants issued					1,100,000			1,100,000
Fair value of beneficial conversion of note plus interest					1,300,000			1,300,000
Convertible notes, amortization of deferred financing costs and accretion of discounts			19,000	0	1,814,000
Credit facility expiration date		31-Oct-14
First Amendment [Member]
Debt Instrument [Line Items]
Credit facility expiration date		31-Mar-15
MidCap Financial SBIC, LP [Member]
Debt Instrument [Line Items]
Convertible notes, interest rate						7.50%
Line of credit facility maximum amount						20,000,000
Credit facility amount			10,000,000			10,000,000
Credit facility expiration date			31-Oct-14
Number of installments for principal payments			36 months
Debt instrument fee amount						50,000
Debt instrument maturity date			1-Jan-19
Debt instrument redemption percentage						6.50%
Notes payable issue for first tranche										10,000,000
Credit facility assigned to Silicon Valley Bank		2,500,000
MidCap Financial SBIC, LP [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Number of tranches						2
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Line of credit facility maximum amount		2,500,000
Warrant [Member]
Debt Instrument [Line Items]
Debt issuance costs, warrants issued for banking services					100,000
Legal and Banking Services [Member]
Debt Instrument [Line Items]
Debt issuance costs for legal and banking services					500,000
Accretion of Series B [Member]
Debt Instrument [Line Items]
Converted notes, amount							175,000
Converted notes, shares							47,064
Series B Preferred Stock [Member]
Debt Instrument [Line Items]
Convertible notes conversion, shares issued	1,463,937
Convertible notes conversion, warrants issued	365,986
Notes Issued in November 2011 [Member]
Debt Instrument [Line Items]
Beneficial conversion feature associated with notes payable	1,000,000
Additional Notes Issued in 2012 [Member]
Debt Instrument [Line Items]
Beneficial conversion feature associated with notes payable	300,000
Mid Cap [Member]
Debt Instrument [Line Items]
Estimated fair value of the debt			10,100,000
Devon Park Bioventures [Member]
Debt Instrument [Line Items]
Issuance of convertible note							3,000,000
Convertible notes, gross proceeds							2,500,000	500,000
Other Investors [Member]
Debt Instrument [Line Items]
Convertible notes, gross proceeds							$1,300,000

Shareholders_Equity_and_Redeem2

Shareholders' Equity and Redeemable Preferred Stock - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended						12 Months Ended			0 Months Ended		1 Months Ended				0 Months Ended		1 Months Ended
	Nov. 30, 2011	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	13-May-14	Nov. 01, 2013	Jul. 31, 2012	Nov. 30, 2011	Nov. 30, 2009	Nov. 30, 2008	Oct. 31, 2012	Jan. 31, 2012	Oct. 30, 2012	Jun. 23, 2014
Capital Unit [Line Items]
Preferred stock, par value				$0.00				$0.00	$0.00											$0.00
Preferred stock shares authorized								5,000,000												5,000,000
Conversion of preferred shares into common shares																				11,979,479
Rights to receive warrants granted	11,766
Proceeds from warrants exercised								$3,780,000	$265,000
Expense to mark warrants to market		1,774,000	1,297,000	1,272,000	32,000	11,000	109,000	3,071,000	1,424,000	62,000
Common stock issued during period, per share																0.03
Common stock, shares authorized				49,574,865				250,000,000	49,574,865											250,000,000
Salem [Member] \| Convertible Notes Payable [Member]
Capital Unit [Line Items]
Rights to receive warrants granted													13,447	57,889
Warrants exercised											344,964	71,336
Proceeds from warrants exercised											2,300,000	300,000
Restricted Stock [Member]
Capital Unit [Line Items]
Vesting period								2 years
Stock repurchase price per share								$0.03							$0.03
Shares of restricted common stock granted																779,919
Restricted stock repurchased, shares															103,663
HemoCleanseLlcMember [Member]
Capital Unit [Line Items]
Common stock issued in exchange for sublicense rights (in shares)																779,919
Common stock issued for sublicense rights																20,000
Investor [Member]
Capital Unit [Line Items]
Rights to receive warrants granted																	365,986
Non Executive [Member]
Capital Unit [Line Items]
Rights to receive warrants granted																		29,247
Series A Preferred Stock [Member]
Capital Unit [Line Items]
Preferred stock, par value				$0.00				$0.00	$0.00
Preferred stock, original issue price								$2.05
Preferred stock shares authorized				1,494,966					1,494,966
Series B Preferred Stock [Member]
Capital Unit [Line Items]
Preferred stock, original issue price								$3.72
Convertible preferred stock, shares issued				2,261,506					2,261,506
Series C Preferred Stock [Member]
Capital Unit [Line Items]
Preferred stock, original issue price								$6.67
Convertible preferred stock, shares issued				6,899,281					6,899,281
Series C Preferred Stock [Member] \| Salem [Member] \| Convertible Notes Payable [Member]
Capital Unit [Line Items]
Rights to receive warrants granted																			344,964
Warrants issued date																			2013-08
Series D Preferred Stock [Member]
Capital Unit [Line Items]
Convertible preferred stock, shares issued								1,858,012
Original issue price								$13.46
Proceeds from issuance of redeemable preferred stock								$24,800,000

Shareholders_Equity_and_Redeem3

Shareholders' Equity and Redeemable Preferred Stock - Total Outstanding Convertible Preferred Stock (Detail) (USD $)	Dec. 31, 2014	Jun. 23, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Jun. 23, 2014	Dec. 31, 2013
Convertible Preferred Stock [Line Items]
Shares Authorized	5,000,000	5,000,000
Shares Issued	0		0
Total Proceeds (Net of Offering Costs)			$51,965
Series A Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Shares Authorized			1,494,966
Shares Issued			582,976
Price Per Share			$2.05
Total Proceeds (Net of Offering Costs)			1,196
Series B Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Shares Authorized			6,768,033
Shares Issued			2,261,506
Price Per Share			$3.72
Total Proceeds (Net of Offering Costs)			8,371
Series C Preferred Stock [Member]
Convertible Preferred Stock [Line Items]
Shares Authorized			17,692,308
Shares Issued			6,899,281
Price Per Share			$6.67
Total Proceeds (Net of Offering Costs)			$42,398

Shareholders_Equity_and_Redeem4

Shareholders' Equity and Redeemable Preferred Stock - Summary of Warrants Exercisable (Detail) (USD $)	0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended	0 Months Ended
	Nov. 01, 2013	Dec. 31, 2013	6-May-14	Dec. 31, 2014	13-May-14	31-May-14	Jun. 05, 2014
Common Stock [Member]
Class of Warrant or Right [Line Items]
Beginning Balance		445,546
Warrant exercised		-71,336
Ending Balance		374,210
Warrant exercised price per unit	$3.72
Common Stock [Member] \| May 6,2014 [Member]
Class of Warrant or Right [Line Items]
Warrant exercised				-9,749
Warrant exercised price per unit			$2.56
Common Stock [Member] \| May 13 ,2014 [Member]
Class of Warrant or Right [Line Items]
Warrant exercised				-344,964
Warrant exercised price per unit					$6.67
Common Stock [Member] \| May 31,2014 [Member]
Class of Warrant or Right [Line Items]
Warrant exercised				-19,497
Warrant exercised price per unit						$2.56
Series B Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Warrant exercised						-340,772	-36,980
Ending Balance		377,752
Warrant exercised price per unit						$3.72	$3.72

ShareBased_Compensation_Additi

Share-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for granting under employee stock option plan	3,841,099
Additional shares of common stock available for granting under employee stock option plan subject to adjustment	1,169,878
Increase in authorized share, description	The number of shares authorized by the plan may be increased each January 1st following the effective date of the plan by the lesser of: a) 4% of the total number of shares outstanding (on an as-converted basis) on December 31st of the preceding year, less the aggregate number of shares available under the plan as of that date (if the result is negative, then this clause equals zero); b) a number of shares determined by the Board of Directors, or c) 1,169,878 (subject to adjustment for any subdivision or consolidation of outstanding shares of Common Stock, declaration of the dividend payable in shares of Common Stock or other stock split).
Weighted-Average Remaining Contractual Life in Years, Exercisable	7 years 5 months 19 days
Stock awards forfeited in vesting period	0
Aggregate intrinsic value of options exercisable	$65.90
Aggregate intrinsic value of options exercised	2.4
Weighted-average grant-date fair value of options granted	$15.31	$2.05	$1.62
Number of options	1,525,135	1,764,566	1,358,520
Share based compensation expense		1.9
Total compensation cost related to nonvested awards not yet recognized	$25.40
Weighted-average period of nonvested awards expected to be recognized	2 years 8 months 27 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting period	10 years
Weighted-Average Remaining Contractual Life in Years, Exercisable	2 years
Certain Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options		2,017,650	2,017,650

ShareBased_Compensation_Weight

Share-Based Compensation - Weighted Average Assumptions Used to Fair Value of Options Granted (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	2.13%	1.87%	1.84%
Volatility	96.90%	102.20%	95.90%
Expected life	6 years 5 months 12 days	7 years	5 years

ShareBased_Compensation_Summar

Share-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Options outstanding, beginning balance	3,286,870	1,522,304	183,281
Weighted-Average Exercise Price Options outstanding, beginning balance	$2.05	$1.95	$1.03
Number of Shares, Options granted	1,525,135	1,764,566	1,358,520
Number of Shares, Options exercised	-79,441		-19,498
Number of Shares, Options outstanding, ending balance	4,732,564	3,286,870	1,522,304	183,281
Number of Shares, Exercisable, ending balance	1,668,413
Weighted-Average Exercise Price, Options granted	$19	$2.13	$2.08
Weighted-Average Exercise Price, Options exercised	$1.98		$1.03
Weighted-Average Exercise Price, Options outstanding, ending balance	$7.52	$2.05	$1.95	$1.03
Weighted-Average Exercise Price, Exercisable, ending balance	$2.07
Weighted-Average Remaining Contractual Life in Years, Options granted	9 years 4 months 28 days	9 years 4 months 2 days	9 years 4 months 21 days
Weighted-Average Remaining Contractual Life in Years, Options exercised	7 years 1 month 28 days		7 years 11 months 19 days
Weighted-Average Remaining Contractual Life in Years, Options outstanding	8 years 3 months 22 days	8 years 9 months 7 days	9 years 1 month 6 days	7 years 9 months
Weighted-Average Remaining Contractual Life in Years, Exercisable	7 years 5 months 19 days

ShareBased_Compensation_Nonves

Share-Based Compensation - Nonvested Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Shares, Nonvested stock options
Number of Shares, Nonvested stock options outstanding, beginning balance	2,572,497	1,201,075	26,517
Granted during the year	1,525,135	1,764,566	1,358,520
Vested during the year	-1,033,481	-393,144	-183,962
Exercised or forfeited during the year	0
Number of Shares, Nonvested stock options outstanding, Ending balance	3,064,151	2,572,497	1,201,075
Weighted- Average Grant Date Fair Value
Nonvested stock options weighted- average grant date fair value, beginning balance	$1.92	$1.64	$0.56
Granted during the year	$15.31	$2.05	$1.62
Vested during the year	$2.07	$1.62	$1.36
Exercised or forfeited during the year	$0	$0	$0
Nonvested stock options weighted- average grant date fair value, ending balance	$7.45	$1.92	$1.64

License_Agreement_Additional_I

License Agreement - Additional Information (Detail) (USD $)	12 Months Ended		1 Months Ended
License Agreement - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Nov. 30, 2008
License Agreement [Line Items]
Royalty rate, net sales of licensed products	5.00%
Royalty expense	$100,000	$100,000
Outstanding royalty expense balance payable	100,000
HemoCleanseLlcMember [Member]
License Agreement [Line Items]
Common stock issued in exchange for sublicense rights			779,919
Royalty income	$0

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Income tax expense	$0	$0	$0
Valuation allowance	39,554,000	17,457,000	4,718,000
Valuation allowance increased amount	22,100,000
Federal NOL carryforward related to the excess tax benefits associated with stock	3,300,000
Net Operating Loss carryforwards, expirations	Begin to expire in 2029
Research tax credit carryforwards, expirations	Begin to expire in 2029
Net operating loss carryforwards expiring unused	1,500,000
Federal research tax credit carryforwards expiring unused	5,196,000	2,403,000	114,000
Accrued income tax payable	0
Income tax examination year	2014
Unceratin tax positions	0	0
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	93,700,000
Federal research tax credit carryforwards expiring unused	100,000
Tax examination period	3 years
Federal [Member] \| Research Tax Credit Carryforward [Member]
Income Taxes [Line Items]
Tax credit carryforwards	5,200,000
State [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$500,000
Tax examination period	4 years

Income_Taxes_Income_Tax_Expens

Income Taxes - Income Tax Expense Reconciliation (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. tax benefit at statutory rate	($21,785)	($11,423)	($3,495)
U.S. state income tax	-303	-383	-105
State effective rate changes	333
Permanent differences	1,044	541	748
Deferred tax valuation allowances	22,097	12,758	2,848
Research and development credit	-1,885	-1,073
Other	499	-420	4
Income tax expense	$0	$0	$0

Income_Taxes_Net_Deferred_Tax_

Income Taxes - Net Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets:
Net operating loss carryforwards	$31,224	$14,325	$4,519
Research and development credit carryforwards	5,196	2,403	114
Stock compensation	3,425	860	160
Other	190	52
Total deferred tax assets	40,035	17,640	4,793
Valuation allowance	-39,554	-17,457	-4,718
Total deferred tax assets, net	481	183	75
Deferred income tax liabilities:
Depreciation and amortization	-481	-183	-75
Total deferred tax assets, net	$0	$0	$0

Defined_Contribution_Plan_Addi

Defined Contribution Plan - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Contribution, percent of employees	3.00%
Safe harbour contributions into 401(k) retirement plan		$0.20

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified	Dec. 31, 2014
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Purchase commitment amount	$1.30
Clinical Materials [Member]
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Purchase commitment amount	$1.50

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Detail) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Share data, unless otherwise specified	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
Costs and expenses:
Research and development	$14,574	[1]	$12,541	[1]	$11,649	[1]	$6,854	[1]	$6,880	[1]	$7,138	[1]	$6,335	[1]	$4,409	[1]	$45,618	$24,762	$6,989
General and administrative	5,535	[2]	4,081	[2]	2,881	[2]	2,422	[2]	3,521	[2]	2,224	[2]	972	[2]	715	[2]	14,919	7,432	1,148
Total costs and expenses	20,109		16,622		14,530		9,276		10,401		9,362		7,307		5,124		60,537	32,194	8,137
Loss from operations	-20,109		-16,622		-14,530		-9,276		-10,401		-9,362		-7,307		-5,124		-60,537	-32,194	-8,137
Other (income) expense:
Interest/other income	-43	[3]	-31	[3]	-11	[3]	-9	[3]	-5	[3]	-5	[3]	-8	[3]	-12	[3]	-94	-30	-17
Interest expense	249	[4]	272	[4]	6	[4]	3	[4]	-4	[4]	3	[4]	5	[4]	5	[4]	530	9	2,099
Expense to mark warrants to market					1,774		1,297		1,272		32		11		109		3,071	1,424	62
Net loss	-20,315		-16,863		-16,299		-10,567		-11,664		-9,392		-7,315		-5,226		-64,044	-33,597	-10,281
Preferred stock accretion					-129		-181		-174		-173		-172		-170		-310	-689	-174
Net loss attributable to common shareholders	($20,315)		($16,863)		($16,428)		($10,748)		($11,838)		($9,565)		($7,487)		($5,396)		($64,354)	($34,286)	($10,455)
Net loss per share attributable to common shareholders, basic and diluted	($0.98)		($0.81)		($4.72)		($6.60)		($7.38)		($6.14)		($4.81)		($3.46)		($5.47)	($21.84)	($6.74)
Weighted-average common shares used to compute net loss per share attributable to common shareholders, basic and diluted	20,832,475		20,818,794		3,482,340		1,628,976		1,604,490		1,557,643		1,557,643		1,557,643		11,768,267	1,569,583	1,552,276

[1]	(1) Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.
[2]	(2) Administrative expenses in the quarter ended December 31, 2013 include $650 of additional legal and professional fees, incurred primarily in support of our product development, $219 of additional consulting fees in support of medical communications and $174 of additional non-cash option expense to mark to market certain stock options recorded as liabilities
[3]	(3) Interest income in the quarters ended September 30, 2014 and December 31, 2014 include interest income on invested surplus cash.
[4]	(4) Interest expense in the quarters ended September 30, 2014 and December 31, 2014 include interest expense related to the MidCap Credit Facility initiated in July 2014 ( See note 6 above) .

Selected_Quarterly_Financial_D3

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Parenthetical) (Detail) (USD $)

3 Months Ended

12 Months Ended

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

Selected Quarterly Financial Data [Line Items]

Research and development expenses

$14,574,000

[1]

$12,541,000

[1]

$11,649,000

[1]

$6,854,000

[1]

$6,880,000

[1]

$7,138,000

[1]

$6,335,000

[1]

$4,409,000

[1]

$45,618,000

$24,762,000

$6,989,000

Additional legal and professional fees

650,000

Additional consulting fees

219,000

Additional non-cash option expense

174,000

Medical Affairs [Member]

Selected Quarterly Financial Data [Line Items]

Research and development expenses

$1,618,000

$1,673,000

$595,000

$254,000

[1]

(1) Research and development expenses in the quarters ending December 31, 2013, March 31, 2014, June 30, 2014 and September 30, 2014 include medicalaffairs expenses previously reported as administrative expenses in the amounts of $254, $1,595, $1,673 and $1,618, respectively.