Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2014	Oct. 31, 2014
Document and Entity Information
Entity Registrant Name	T2 Biosystems, Inc.
Entity Central Index Key	0001492674
Document Type	10-Q
Document Period End Date	Sep. 30, 2014
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		20,041,645
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q3

Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 75,589	$ 30,198
Prepaid expenses and other current assets	1,087	195
Total current assets	76,676	30,393
Property and equipment, net	1,698	1,118
Restricted cash	340	340
Other assets	153	34
Total assets	78,867	31,885
Current liabilities:
Accounts payable	725	943
Accrued expenses	5,580	1,319
Current portion of notes payable	290	1,759
Current portion of deferred rent	67	25
Total current liabilities	6,662	4,046
Notes payable, net of current portion	10,733	3,299
Deferred rent, net of current portion	18	45
Warrants to purchase redeemable securities		1,225
Other liabilities	24
Commitments and contingencies
Redeemable convertible preferred stock - Prior to conversion		112,813
Stockholders' equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued
Common stock, $0.001 par value; 200,000,000 and 28,254,907 shares authorized at September 30, 2014 and December 31, 2013, respectively; 20,040,604 and 1,411,986 shares issued and outstanding at September 30, 2014 and December 31, 2013, respectively	20	1
Additional paid-in capital	155,929
Accumulated deficit	(94,519)	(89,544)
Total stockholders' equity (deficit)	61,430	(89,543)
Total liabilities, redeemable convertible preferred stock and stockholders' equity (deficit)	$ 78,867	$ 31,885

Condensed Balance Sheet (Parentheticals) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Condensed Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	28,254,907
Common stock, shares issued	20,040,604	1,411,986
Common stock, shares outstanding	20,040,604	1,411,986

Condensed Statements of Operations and Comprehensive loss (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Consolidated Statements of Operations and Comprehensive Loss
Research and grant revenue		$ 91		$ 211
Operating expenses:
Research and development	4,803	3,358	14,572	10,646
Selling, general and administrative	2,984	1,275	7,271	3,618
Total operating expenses	7,787	4,633	21,843	14,264
Loss from operations	(7,787)	(4,542)	(21,843)	(14,053)
Interest expense, net	(304)	(100)	(471)	(310)
Other income (expense), net			(1)	125
Net loss	(8,091)	(4,642)	(22,315)	(14,238)
Comprehensive loss	(8,091)	(4,642)	(22,315)	(14,238)
Reconciliation of net loss to net loss applicable to common stockholders:
Net loss	(8,091)	(4,642)	(22,315)	(14,238)
Accretion of redeemable convertible preferred stock to redemption value	(758)	(1,911)	(4,570)	(4,998)
Net loss applicable to common stockholders	$ (8,849)	$ (6,553)	$ (26,885)	$ (19,236)
Net loss per share applicable to common stockholders - basic and diluted	$ (0.71)	$ (4.69)	$ (5.25)	$ (13.82)
Weighted-average number of common shares used in computing net loss per share applicable to common stockholders - basic and diluted	12,379,337	1,398,425	5,120,977	1,392,110

Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities
Net loss	$ (22,315)	$ (14,238)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	459	438
Stock-based compensation expense	1,057	340
Noncash interest expense	102	33
Change in fair value of warrants	1	(110)
Loss on disposal of asset		6
Deferred rent	15	(4)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(901)	(97)
Accounts payable	(227)	(49)
Accrued expenses	2,110	206
Net cash used in operating activities	(19,699)	(13,475)
Investing activities
Purchases of property and equipment	(1,039)	(450)
Decrease in restricted cash		80
Net cash used in investing activities	(1,039)	(370)
Financing activities
Proceeds from issuance of common stock in initial public offering, net of offering costs	60,145
Proceeds from issuance of redeemable convertible preferred stock, net		39,768
Proceeds from issuance of common stock and stock options exercises	150	38
Proceeds from notes payable, net of deferred financing costs	9,800
Repayments of notes payable	(3,966)	(451)
Net cash provided by financing activities	66,129	39,355
Net increase in cash and cash equivalents	45,391	25,510
Cash and cash equivalents at beginning of period	30,198	9,709
Cash and cash equivalents at end of period	75,589	35,219
Supplemental disclosures of cash flow information
Cash paid for interest	294	251
Supplemental disclosures of noncash investing and financing activities
Accretion of Series A-1, A-2, B, C, D and E redeemable convertible preferred stock to redemption value	4,570	4,998
Deferred financing costs incurred but unpaid at period end	80
Initial public offering costs incurred but unpaid at period end	2,104
Conversion of redeemable convertible preferred stock to common stock	117,383
Conversion of preferred stock warrants to common stock	$ 1,226

Nature of Business	9 Months Ended
Nature of Business	Sep. 30, 2014
Nature of Business
Nature of Business	1. Nature of Business T2 Biosystems, Inc. (the “Company”) was incorporated on April 27, 2006 as a Delaware corporation with operations based in Lexington, Massachusetts. The Company is an in vitro diagnostic company that has developed an innovative and proprietary platform that enables rapid, sensitive and simple direct detection of pathogens, biomarkers and other abnormalities across a variety of unpurified patient sample types. The Company is using its T2 Magnetic Resonance platform (“T2MR”) to develop a broad set of applications aimed at reducing mortality rates, improving patient outcomes and reducing the cost of healthcare by helping medical professionals make targeted treatment decisions earlier. The Company’s initial development efforts target sepsis and hemostasis, areas of significant unmet medical need in which existing therapies could be more effective with improved diagnostics. On September 22, 2014, the Company received market authorization from the U.S. Food and Drug Administration (“FDA”) for its first two products, the T2Dx diagnostic instrument (“T2Dx”) and T2Candida panel (“T2Candida”). Since inception, the Company has devoted substantially all of its efforts to research and development, business planning, recruiting management and technical staff, acquiring operating assets, raising capital, and, most recently, commercialization of its products. Liquidity At September 30, 2014 the Company has generated an accumulated deficit of $94.5 million (see Note 6 for additional disclosure of the effects of the initial public offering on accumulated deficit). The future success of the Company is dependent on its ability to successfully commercialize its newly authorized products, obtain regulatory clearance for and successfully launch its future product candidates and ultimately attain profitable operations, and obtain additional capital, if needed. Historically, the Company has funded its operations primarily through private placements of its redeemable convertible preferred stock and through debt financing arrangements. On August 12, 2014, the Company completed its initial public offering (“IPO”) whereby the Company sold 5,980,000 shares of its common stock for net proceeds of approximately $58.0 million (Note 6). As a result of the completion of the IPO and additional liquidity of up to $30.0 million available from the loan and security agreement that closed on July 11, 2014 (Note 5), management believes that its cash resources will be sufficient to allow the Company to fund its current operating plan through at least the next 18 months. The Company is subject to a number of risks similar to other newly commercial life science companies, including, but not limited to commercially launching the Company’s products, development and market acceptance of the Company’s future product candidates, development by its competitors of new technological innovations, protection of proprietary technology, and raising additional capital.

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2014
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). Unaudited Interim Financial Information Certain information and footnote disclosures normally included in the Company’s annual financial statement have been condensed or omitted. Accordingly, these interim condensed financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Registration Statement on Form S-1 filed on August 6, 2014, which includes the annual financial statements for the fiscal year ended December 31, 2013. The accompanying interim balance sheet as of September 30, 2014, the statements of operations and comprehensive loss for the three and nine months ended September 30, 2014 and 2013, the statements of cash flows for the nine months ended September 30, 2014 and 2013 and the related financial data and other information disclosed in these notes are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements, and, in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2014, and the results of its operations and its cash flows for the three and nine months ended September 30, 2014 and 2013. The results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014, any other interim periods, or any future year or period. Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company views its operations and manages its business in one operating segment, which is the business of developing and launching commercially its diagnostic products aimed at reducing mortality rates, improving patient outcomes and reducing the cost of healthcare by helping medical professionals make targeted treatment decisions earlier. Inventory Inventory is stated at the lower of cost or market with cost determined under the first-in, first-out basis. The Company capitalizes inventories in preparation for sales of products when the related product candidates are considered to have a high likelihood of regulatory clearance and the related costs are expected to be recoverable through sales of the inventories. In addition, the Company capitalizes inventories related to the manufacture of instruments that have a high likelihood of regulatory clearance and will be retained as the Company’s assets, upon determination that the instrument has alternative future uses. In determining whether or not to capitalize such inventories, the Company evaluates, among other factors, information regarding the product candidate’s status of regulatory submissions and communications with regulatory authorities, the outlook for commercial sales and alternative future uses of the product candidate, including commercial sale. Costs associated with development products prior to satisfying the inventory capitalization criteria are charged to research and development expense as incurred. The Company began capitalizing inventories upon receipt of market authorization from the FDA for its first two products. Inventory meeting the capitalization criteria as of September 30, 2014 is not significant to the financial statements and is recorded as a component of prepaid expenses and other current assets in the Condensed Balance Sheets. Reverse Stock Split The Company effected a 1-for-1.7 reverse stock split of its issued and outstanding common stock on July 25, 2014. All share and per share amounts related to issued and outstanding common stock, outstanding options and warrants exercisable for common stock included in these financial statements and notes to the financial statements and have been retroactively adjusted for all periods presented to reflect the reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The shares authorized, issued and outstanding of the Company’s redeemable convertible preferred stock are not impacted by the reverse stock split and have not been adjusted. However, the conversion ratios of the Company’s redeemable convertible preferred stock for the purpose of determining the common stock issued upon conversion (Note 6) have been adjusted to reflect the reverse stock split. Net Loss Per Share Basic net loss per share is calculated by dividing net loss applicable to common stockholders, which is net loss plus accretion of redeemable convertible preferred stock to redemption value in the period, by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting the weighted-average number of shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method for outstanding stock options and warrants. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock and stock options are considered to be common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect, including the related impact to the numerator of the fair value adjustment of the warrant and the impact to the denominator of the warrant shares, would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. Guarantees From time to time, the Company enters into indemnification agreements in the ordinary course of business, including, but not limited to, indemnification agreements with directors and officers, within its lease agreements for office, laboratory and manufacturing space, and with certain suppliers and business partners. As of September 30, 2014 and December 31, 2013, the Company had not experienced any material losses related to these indemnification obligations, and no material claims with respect thereto were outstanding. The Company does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established. Recently Issued or Adopted Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In June 2014, the FASB issued amended guidance, ASU No 2014-09, Revenue from Contracts with Customers, which is applicable to revenue recognition that will be effective for the Company for the year ended December 31, 2017. The new guidance must be adopted using either a full retrospective approach for all periods presented or a modified retrospective approach. Early adoption is not permitted. The new guidance applies a more principles-based approach to revenue recognition. The Company is evaluating the new guidance and the expected effect on the Company’s condensed financial statements. In June 2014, the FASB issued ASU 2014-10, Development Stage Entities (Topic 915) (“ASU 2014-10”), which removes the definition of a development stage entity from the ASC, thereby removing the financial reporting distinction between development stage entities and other reporting entities. Accordingly, ASU 2014-10 eliminates the requirements for development stage entities to (1) present inception-to-date information in the statements of operations, cash flows and shareholder equity, (2) label financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged, and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. ASU 2014-10 is effective for public business entities for annual periods beginning after December 15, 2014, and interim reporting periods beginning after December 15, 2015, with early adoption permitted. The Company has adopted the provisions of ASU 2014-10 in the June 30, 2014 Quarterly Report on Form 10-Q.

- Definition

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

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Fair Value Measurements

9 Months Ended

Sep. 30, 2014

Fair Value Measurements

Fair Value Measurements

3. Fair Value Measurements

The Company measures the following financial assets and liabilities at fair value on a recurring basis. In general, fair values determined by Level 1 inputs utilize observable inputs such as quoted prices in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are either directly or indirectly observable, such as quoted prices, interest rates and yield curves. Fair values determined by Level 3 inputs utilize unobservable data points in which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability. The Company has not changed the manner in which it values the liability for warrants to purchase redeemable securities, which is measured at fair value using Level 3 inputs. There were no transfers between levels of the fair value hierarchy during any of the periods presented. The following tables set forth the Company’s financial assets and liabilities carried at fair value categorized using the lowest level of input applicable to each financial instrument as of September 30, 2014 and December 31, 2013 (in thousands):

	Balance at September 30, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	65,119	$	65,119	$	—	$	—
Money market funds	10,470		10,470		—		—
Restricted cash	340		340		—		—
	$	75,929	$	75,929	$	—	$	—
Liabilities:
Warrants to purchase redeemable securities	$	—	$	—	$	—	$	—
	$	—	$	—	$	—	$	—

	Balance at December 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	2,631	$	2,631	$	—	$	—
Money market funds	27,567		27,567		—		—
Restricted cash	340		340		—		—
	$	30,538	$	30,538	$	—	$	—
Liabilities:
Warrants to purchase redeemable securities	$	1,225	$	—	$	—	$	1,225
	$	1,225	$	—	$	—	$	1,225

The fair value of the Company’s preferred stock warrant liability represents a recurring measurement that is classified within Level 3 of the fair value hierarchy, wherein fair value is estimated using significant unobservable inputs. The Company determined the fair value of the warrants to purchase redeemable convertible preferred stock based on input from management and the board of directors, which utilized an independent valuation of the Company’s enterprise value, determined utilizing an analytical valuation model, which as of August 6, 2014, the date just prior to the net exercise of the warrants into commons stock, was a hybrid approach based on an Option Pricing Model (OPM) and the Probability Weighted Expected Return Method (PWERM). Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions affecting the in vitro diagnostics industry sector, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities at the time and the likelihood of achieving a liquidity event, such as an initial public offering or a sale of the Company. Any changes in the assumptions used in the valuation could materially affect the financial results of the Company. The following table sets forth a summary of changes in the fair value of the Company’s preferred stock warrant liability (in thousands):

	Nine Months Ended September 30,
	2014
Beginning balance	$	1,225
Additional warrants issued	—
Change in fair value, recorded as a component of other income (expense)	1
Net exercise of warrants into common stock	(1,226		)
Ending balance	$	—

For certain financial instruments, including accounts payable and accrued expenses, the carrying amounts approximate their fair values as of September 30, 2014 and December 31, 2013 because of their short-term nature. At September 30, 2014 and December 31, 2013, the carrying value of the Company’s debt approximated fair value, which was determined using Level 3 inputs, including a quoted interest rate.

- Definition

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

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Supplemental Balance Sheet Information

9 Months Ended

Sep. 30, 2014

Supplemental Balance Sheet Information

Supplemental Balance Sheet Information

4. Supplemental Balance Sheet Information

Accrued Expenses

Accrued expenses consist of the following (in thousands):

	September 30,		December 31,
	2014		2013
Accrued professional services	$	3,038	$	101
Accrued payroll and compensation	1,287		496
Accrued research and development expenses	257		422
Other accrued expenses	998		300
Total accrued expenses	$	5,580	$	1,319

Debt	9 Months Ended
Debt	Sep. 30, 2014
Debt
Debt	5. Debt On July 11, 2014, the Company entered into a loan and security agreement (“the Note Agreement”) with two lenders to borrow up to $30.0 million for operations. The Note Agreement allows the Company to borrow amounts in two tranches, up to $20.0 million (drawn in amounts not less than $10.0 million upon closing and the remainder drawn in amounts not less than $5.0 million draws) by December 31, 2014 for tranche A and up to $10.0 million by June 30, 2015 for tranche B. Under the Note Agreement, borrowings under tranche B are only available to the Company if both of the following conditions are met by June 30, 2015: (a) the Company receives Section 510(k) clearance from the FDA on the Company’s T2Dx and T2Candida products and (b) the Company completes a public or private stock offering, equity raise or strategic partner arrangement resulting in the receipt of at least $30.0 million in net proceeds by the Company. As the Company received FDA approval in September 2014 and the Company closed its initial public offering in August 2014, the borrowings under tranche B are now available as both of the required conditions have been met. Through September 30, 2014, the Company received proceeds of $9.8 million under tranche A, net of deferred financing costs. To date, the Company has not drawn the remaining tranche A and tranche B available borrowings. The amounts borrowed under the Note Agreement are collateralized by substantially all of the assets of the Company and bear interest at the one-month LIBOR plus 7.05%, which was 7.21% on September 30, 2014. The Company will pay interest only payments on the amounts borrowed under the Note Agreement through July 31, 2016. After the interest only period, the Company will repay the amounts borrowed in equal monthly installments until the maturity date of July 1, 2019. The Note Agreement requires payment of a final fee of 4.75% of the aggregate original principal of amounts borrowed, which the Company is accruing over the term of the Note Agreement. In addition, amounts borrowed may be prepaid at the option of the Company in denominations of not less than $1,000,000, and any amounts prepaid are subject to a prepayment premium of 1.5% if prepaid prior to the first anniversary of the borrowing date, 1.0% if prepaid prior to the second anniversary of the borrowing date and after the first anniversary of the borrowing date, and 0.5% if prepaid prior to the maturity date and after the second anniversary of the borrowing date. The effective interest rate for the Note Agreement, including final fee interest and non-cash interest, is 9.44%. The Note Agreement does not include any financial covenants, but does contain a subjective acceleration clause whereby upon an event of default, which includes a material adverse change in the business, operations, or conditions (financial or otherwise) of the Company or a material impairment of the prospect of repayment of any portion of the obligations, there can be an immediate acceleration of the borrowings under the Note Agreement. The Company concluded that a material adverse change has not occurred and is unlikely to occur and therefore the debt has been classified as a long-term liability. The Company assessed all terms and features of the Note Agreement in order to identify any potential embedded features that would require bifurcation or any beneficial conversion features. As part of this analysis, the Company assessed the economic characteristics and risks of the Note Agreement, including put and call features. The Company determined that all features of the Note Agreement are clearly and closely associated with a debt host and do not require bifurcation as a derivative liability, or the fair value of the feature is immaterial. The Company will continue to reassess the features to determine if they require separate accounting on a quarterly basis. In connection with the closing of the Note Agreement, the Company repaid all amounts outstanding under previously existing borrowing arrangement with a lender, totaling approximately $2.9 million, as of July 11, 2014.

- Definition

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

+ References+ Details

Stockholders' Equity (Deficit)

9 Months Ended

Sep. 30, 2014

Stockholders' Equity Note [Abstract]

Stockholders' Equity (Deficit)

6. Stockholders’ Equity (Deficit)

Initial Public Offering

On August 12, 2014, the Company completed its IPO, whereby the Company sold 5,980,000 shares of its common stock (inclusive of 780,000 shares of common stock sold by the Company pursuant to the full exercise of an overallotment option granted to the underwriters in connection with the offering) at a price of $11.00 per share. The shares began trading on the Nasdaq Global Market on August 7, 2014. The net proceeds received by the Company from the offering were approximately $58.0 million, after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. At September 30, 2014, offering expenses related to the IPO totaling $2.1 million were incurred, but unpaid. Upon the closing of the IPO, all outstanding shares of redeemable convertible preferred stock converted into 12,516,298 shares of common stock and warrants exercisable for redeemable convertible preferred stock net exercised into 68,700 shares of common stock, resulting in a reclassification of the related liability for warrants to purchase redeemable convertible preferred stock to common stock (par value) and additional paid-in capital. On the conversion date, the redeemable convertible preferred stock had a balance of $117.4 million, which was recorded in temporary equity. Upon conversion into common stock, this balance was reclassified as stockholders’ equity, reducing accumulated deficit by $21.0 million, with the residual amount of $96.4 million recorded as common stock (par value) and additional paid-in capital. The amount recorded as a reduction in accumulated deficit reflects the value of redeemable convertible preferred stock dividends and issuance costs accreted through the conversion date. In addition, the following other items became effective with the closing of the IPO:

(i)

On July 25, 2014, the Company filed an amendment to the Certificate of Incorporation to effect the aforementioned stock split, increase the authorized number of shares of common stock from 29,880,899 to 60,000,000, eliminate anti-dilution protection for the preferred stock in the connection with the issuance of common stock as part of the IPO and amend the mandatory conversion provision to remove the minimum price per share and minimum gross proceeds conditions in connection with the IPO. Upon closing of the IPO, the number of authorized shares of common stock of the Company increased to 200,000,000 and the Company is authorized to issue up to 10,000,000 shares of preferred stock.

(ii)

On July 19, 2014, the Company’s board of directors adopted and, on July 21, 2014, the Company’s stockholders approved, the 2014 Incentive Award Plan (“2014 Plan”), which became effective on August 6, 2014. The 2014 Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors are eligible to receive awards under the 2014 Plan.

(iii)

On July 19, 2014, the Company’s board of directors adopted and, on July 21, 2014, the Company’s stockholders approved, the 2014 Employee Stock Purchase Plan (“2014 ESPP”), which became effective on August 6, 2014. The 2014 ESPP will enable eligible employees to purchase shares of the Company’s common stock at a discount.

Stock-Based Compensation

2006 Stock Incentive Plan

The Company’s 2006 Stock Option Plan (“the 2006 Plan”) was established for granting stock incentive awards to directors, officers, employees and consultants to the Company. Upon closing of the Company’s IPO in August 2014, the Company ceased granting stock incentive awards under the 2006 Plan. The 2006 Plan provided for the grant of incentive and non-qualified stock options and restricted stock grants as determined by the Board of Directors. Under the 2006 Plan, stock options were generally granted with exercise prices equal to or greater than the fair value of the common stock as determined by the board of directors, expired no later than 10 years from the date of grant, and vest over various periods not exceeding 4 years.

2014 Stock Incentive Plan

The Company’s 2014 Plan provides for the issuance of shares of common stock in the form of stock options, awards of restricted stock, awards of restricted stock unit awards, performance awards, dividend equivalent awards, stock payment awards and stock appreciation rights to directors, officers, employees and consultants of the Company. Since the establishment of the 2014 Plan, the Company has only granted stock options. Generally, stock options are granted with exercise prices equal to or greater than the fair value of the common stock on the date of grant, expire no later than 10 years from the date of grant, and vest over various periods not exceeding 4 years.

The number of shares reserved for future issuance under the 2014 Plan is the sum of (1) 823,529, (2) any shares that were granted under the 2006 Plan which are forfeited, lapse unexercised or are settled in cash subsequent to the effective date of the 2014 Plan and (3) an annual increase on the first day of each calendar year beginning January 1, 2015 and ending on January 1, 2024, equal to the lesser of (A) 823,529 shares, (B) 4% of the shares outstanding (on an as-converted basis) on the final day of the immediately preceding calendar year and (C) such smaller number of shares determined by the Board of Directors. As of September 30, 2014 there were 667,717 shares available for future grant under the Plan.

Stock Options

During the nine months ended September 30, 2014, the Company granted options with an aggregate fair value of $3,843,000, which are being amortized into compensation expense over the vesting period of the options as the services are being provided. The following is a summary of option activity under the Plans:

	Number of Shares		Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2013	2,265,973		$	2.53	8.23	11,510
Granted	672,972		11.98
Exercised	(63,602	)	2.35
Cancelled	(84,026	)	2.44
Outstanding at September 30, 2014	2,791,317		4.82		8.04	37,039
Exercisable at September 30, 2014	1,281,272		2.24		6.65	20,303
Vested or expected to vest at September 30, 2014	2,433,313		4.59		7.89	32,850

The total fair values of stock options that vested during the nine months ended September 30, 2014 was $812,000.

The weighted-average fair values of options granted in the nine-month periods ended September 30, 2014 and 2013 were $5.71 per share and $1.85 per share, respectively, and were calculated using the following estimated assumptions:

	Nine Months Ended September 30,
	2014	2013
Weighted-average risk-free interest rate	1.85% - 2.04%	1.02% - 1.78%
Expected dividend yield	0.00%	0.00%
Expected volatility	60% - 62%	63% - 64%
Expected terms	5.75 - 6.08 years	5.77 - 6.08 years

Employee Stock Purchase Plan

The 2014 ESPP provides initially for the granting of up to 220,588 shares of the Company’s common stock to eligible employees. The 2014 ESPP plan period is semi-annual and allows participants to purchase the Company’s common stock at 85% of the lower of (i) the market value per share of common stock on the first day of the offering period or (ii) the market value per share of the common stock on the purchase date. Each participant can purchase up to a maximum of $25,000 per year in fair market value, as determined by the market value per share of common stock at the beginning of the offering period. The first plan period began on August 7, 2014. Stock-based compensation expense from the 2014 ESPP for the three- and nine-months ended September 30, 2014 was $39,000.

Stock-Based Compensation Expense

The following table summarizes the stock-based compensation expense for stock options granted to employees and the and nonemployees, as well as stock-compensation expense for the 2014 ESPP that was recorded in the Company’s results of operations for the three and nine months ended September 30, 2014 and 2013 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2014		2013		2014		2013
Research and development	$	127	$	37	$	250	$	117
Selling, general and administrative	425		76		807		223
Total stock-based compensation expense	$	552	$	113	$	1,057	$	340

As of September 30, 2014, there was $3,889,000 of total unrecognized compensation cost related to non-vested stock options granted under the 2006 and 2014 Plans. Total unrecognized compensation cost will be adjusted for future changes in the estimated forfeiture rate. The Company expects to recognize that cost over a remaining weighted-average period of 3.2 years as of September 30, 2014.

- Definition

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

+ References

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-Glossary Preferred Stock

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+ Details

Net Loss Per Share

9 Months Ended

Sep. 30, 2014

Net Loss Per Share

Net Loss Per Share

7. Net Loss Per Share

The following shares were excluded from the calculation of diluted net loss per share applicable to common stockholders, prior to the application of the treasury stock method, because their effect would have been anti-dilutive for the periods presented:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2014	2013	2014	2013
Redeemable convertible preferred stock	—	12,516,298	—	12,516,298
Options to purchase common shares	2,791,317	2,033,450	2,791,317	2,033,450
Warrants to purchase redeemable convertible preferred stock	—	147,484	—	147,484
Total	2,791,317	14,697,232	2,791,317	14,697,232

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	8. Commitments and Contingencies Lease Amendment On July 11, 2014, the Company entered into a lease amendment to expand facilities at the Company’s headquarters in Lexington, MA. The term of the lease amendment ends concurrently with the original lease entered into in August 2010 and will increase the monthly base rent by approximately $39,000 per month through December 2015. The Company retains the option to extend the lease for one additional term of two years.

- Definition

The entire disclosure for commitments and contingencies.

+ References+ Details

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2014
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The Company’s financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Unaudited Interim Financial Information	Unaudited Interim Financial Information Certain information and footnote disclosures normally included in the Company’s annual financial statement have been condensed or omitted. Accordingly, these interim condensed financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Registration Statement on Form S-1 filed on August 6, 2014, which includes the annual financial statements for the fiscal year ended December 31, 2013. The accompanying interim balance sheet as of September 30, 2014, the statements of operations and comprehensive loss for the three and nine months ended September 30, 2014 and 2013, the statements of cash flows for the nine months ended September 30, 2014 and 2013 and the related financial data and other information disclosed in these notes are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements, and, in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2014, and the results of its operations and its cash flows for the three and nine months ended September 30, 2014 and 2013. The results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014, any other interim periods, or any future year or period.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the Chief Executive Officer. The Company views its operations and manages its business in one operating segment, which is the business of developing and launching commercially its diagnostic products aimed at reducing mortality rates, improving patient outcomes and reducing the cost of healthcare by helping medical professionals make targeted treatment decisions earlier.
Inventory	Inventory Inventory is stated at the lower of cost or market with cost determined under the first-in, first-out basis. The Company capitalizes inventories in preparation for sales of products when the related product candidates are considered to have a high likelihood of regulatory clearance and the related costs are expected to be recoverable through sales of the inventories. In addition, the Company capitalizes inventories related to the manufacture of instruments that have a high likelihood of regulatory clearance and will be retained as the Company’s assets, upon determination that the instrument has alternative future uses. In determining whether or not to capitalize such inventories, the Company evaluates, among other factors, information regarding the product candidate’s status of regulatory submissions and communications with regulatory authorities, the outlook for commercial sales and alternative future uses of the product candidate, including commercial sale. Costs associated with development products prior to satisfying the inventory capitalization criteria are charged to research and development expense as incurred. The Company began capitalizing inventories upon receipt of market authorization from the FDA for its first two products. Inventory meeting the capitalization criteria as of September 30, 2014 is not significant to the financial statements and is recorded as a component of prepaid expenses and other current assets in the Condensed Balance Sheets.
Reverse Stock Split	Reverse Stock Split The Company effected a 1-for-1.7 reverse stock split of its issued and outstanding common stock on July 25, 2014. All share and per share amounts related to issued and outstanding common stock, outstanding options and warrants exercisable for common stock included in these financial statements and notes to the financial statements and have been retroactively adjusted for all periods presented to reflect the reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. The shares authorized, issued and outstanding of the Company’s redeemable convertible preferred stock are not impacted by the reverse stock split and have not been adjusted. However, the conversion ratios of the Company’s redeemable convertible preferred stock for the purpose of determining the common stock issued upon conversion (Note 6) have been adjusted to reflect the reverse stock split.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss applicable to common stockholders, which is net loss plus accretion of redeemable convertible preferred stock to redemption value in the period, by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting the weighted-average number of shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method for outstanding stock options and warrants. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock and stock options are considered to be common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect, including the related impact to the numerator of the fair value adjustment of the warrant and the impact to the denominator of the warrant shares, would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented.
Guarantees	Guarantees From time to time, the Company enters into indemnification agreements in the ordinary course of business, including, but not limited to, indemnification agreements with directors and officers, within its lease agreements for office, laboratory and manufacturing space, and with certain suppliers and business partners. As of September 30, 2014 and December 31, 2013, the Company had not experienced any material losses related to these indemnification obligations, and no material claims with respect thereto were outstanding. The Company does not expect significant claims related to these indemnification obligations and, consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established.
Recently Adopted Accounting Pronouncements	Recently Issued or Adopted Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In June 2014, the FASB issued amended guidance, ASU No 2014-09, Revenue from Contracts with Customers, which is applicable to revenue recognition that will be effective for the Company for the year ended December 31, 2017. The new guidance must be adopted using either a full retrospective approach for all periods presented or a modified retrospective approach. Early adoption is not permitted. The new guidance applies a more principles-based approach to revenue recognition. The Company is evaluating the new guidance and the expected effect on the Company’s condensed financial statements. In June 2014, the FASB issued ASU 2014-10, Development Stage Entities (Topic 915) (“ASU 2014-10”), which removes the definition of a development stage entity from the ASC, thereby removing the financial reporting distinction between development stage entities and other reporting entities. Accordingly, ASU 2014-10 eliminates the requirements for development stage entities to (1) present inception-to-date information in the statements of operations, cash flows and shareholder equity, (2) label financial statements as those of a development stage entity, (3) disclose a description of the development stage activities in which the entity is engaged, and (4) disclose in the first year in which the entity is no longer a development stage entity that in prior years it had been in the development stage. ASU 2014-10 is effective for public business entities for annual periods beginning after December 15, 2014, and interim reporting periods beginning after December 15, 2015, with early adoption permitted. The Company has adopted the provisions of ASU 2014-10 in the June 30, 2014 Quarterly Report on Form 10-Q.

- Definition

Disclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.

+ References+ Details

- Definition

Disclosure of accounting policy for major classes of inventories, bases of stating inventories (for example, lower of cost or market), methods by which amounts are added and removed from inventory classes (for example, FIFO, LIFO, or average cost), loss recognition on impairment of inventories, and situations in which inventories are stated above cost. If inventory is carried at cost, this disclosure includes the nature of the cost elements included in inventory.

+ References+ Details

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Measurements

Schedule of financial assets and liabilities at fair value on a recurring basis

The following tables set forth the Company’s financial assets and liabilities carried at fair value categorized using the lowest level of input applicable to each financial instrument as of September 30, 2014 and December 31, 2013 (in thousands):

	Balance at September 30, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	65,119	$	65,119	$	—	$	—
Money market funds	10,470		10,470		—		—
Restricted cash	340		340		—		—
	$	75,929	$	75,929	$	—	$	—
Liabilities:
Warrants to purchase redeemable securities	$	—	$	—	$	—	$	—
	$	—	$	—	$	—	$	—

	Balance at December 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash	$	2,631	$	2,631	$	—	$	—
Money market funds	27,567		27,567		—		—
Restricted cash	340		340		—		—
	$	30,538	$	30,538	$	—	$	—
Liabilities:
Warrants to purchase redeemable securities	$	1,225	$	—	$	—	$	1,225
	$	1,225	$	—	$	—	$	1,225

Summary of changes in the fair value of the Company's preferred stock warrant liability

The following table sets forth a summary of changes in the fair value of the Company’s preferred stock warrant liability (in thousands):

	Nine Months Ended September 30,
	2014
Beginning balance	$	1,225
Additional warrants issued	—
Change in fair value, recorded as a component of other income (expense)	1
Net exercise of warrants into common stock	(1,226		)
Ending balance	$	—

- Definition

Tabular disclosure of the fair value measurement of liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and gains or losses recognized in other comprehensive income (loss) and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs) by class of liability.

+ References+ Details

Supplemental Balance Sheet Information (Tables)

9 Months Ended

Sep. 30, 2014

Supplemental Balance Sheet Information

Components of Accrued expenses

Accrued expenses consist of the following (in thousands):

	September 30,		December 31,
	2014		2013
Accrued professional services	$	3,038	$	101
Accrued payroll and compensation	1,287		496
Accrued research and development expenses	257		422
Other accrued expenses	998		300
Total accrued expenses	$	5,580	$	1,319

Stockholders' Equity Deficit (Tables)

9 Months Ended

Sep. 30, 2014

Stockholders' Equity Note [Abstract]

Summary of stock option activity

	Number of Shares		Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (In years)	Aggregate Intrinsic Value (In thousands)
Outstanding at December 31, 2013	2,265,973		$	2.53	8.23	11,510
Granted	672,972		11.98
Exercised	(63,602	)	2.35
Cancelled	(84,026	)	2.44
Outstanding at September 30, 2014	2,791,317		4.82		8.04	37,039
Exercisable at September 30, 2014	1,281,272		2.24		6.65	20,303
Vested or expected to vest at September 30, 2014	2,433,313		4.59		7.89	32,850

Schedule of estimated assumptions used to calculate weighted-average fair value of options granted

	Nine Months Ended September 30,
	2014	2013
Weighted-average risk-free interest rate	1.85% - 2.04%	1.02% - 1.78%
Expected dividend yield	0.00%	0.00%
Expected volatility	60% - 62%	63% - 64%

Summary of stock-based compensation expense for stock options granted that was recorded in the Company's results of operations

	Three Months Ended September 30,				Nine Months Ended September 30,
	2014		2013		2014		2013
Research and development	$	127	$	37	$	250	$	117
Selling, general and administrative	425		76		807		223
Total stock-based compensation expense	$	552	$	113	$	1,057	$	340

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2014

Net Loss Per Share

Schedule of shares excluded from the calculation where the inclusion would be anti-dilutive

	Three Months Ended September 30,		Nine Months Ended September 30,
	2014	2013	2014	2013
Redeemable convertible preferred stock	—	12,516,298	—	12,516,298
Options to purchase common shares	2,791,317	2,033,450	2,791,317	2,033,450
Warrants to purchase redeemable convertible preferred stock	—	147,484	—	147,484
Total	2,791,317	14,697,232	2,791,317	14,697,232

Nature of Business (Details) (USD $)	9 Months Ended			0 Months Ended
Nature of Business (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Jul. 11, 2014 Loan and Security Agreement [Member]	Aug. 12, 2014 IPO [Member]	Jul. 11, 2014 IPO [Member] Loan and Security Agreement [Member]
Debt instrument
Deficit accumulated in the development stage	$ 94,519,000	$ 89,544,000
Shares issued upon completion of IPO				5,980,000
Proceeds from issuance of common stock in initial public offering, net of offering costs	60,145,000			58,000,000
Maximum borrowings available			$ 30,000,000		$ 30,000,000
Period over which cash resources will be sufficient to allow Company to fund current operating plan				18 months

Summary of Significant Accounting Policies (Details)	0 Months Ended	9 Months Ended
Summary of Significant Accounting Policies (Details)	Jul. 25, 2014	Sep. 30, 2014 segment
Segment Information
Number of Operating Segments		1
Reverse stock split
Stock split conversion ratio	0.588

Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair value measurements
Transfers of assets from level 1 to 2	$ 0	$ 0
Transfers of assets from level 2 to 1	0	0
Transfer of liabilities from level 1 to 2	0	0
Transfer of liabilities from level 2 to 1	0	0
Transfer of liabilities to or from level 3	0	0
Recurring \| Fair value
Assets:
Restricted cash	340	340
Total assets	75,929	30,538
Liabilities:
Warrants to purchase redeemable securities		1,225
Total liabilities		1,225
Recurring \| Fair value \| Cash
Assets:
Cash and cash equivalents	65,119	2,631
Recurring \| Fair value \| Money market funds
Assets:
Cash and cash equivalents	10,470	27,567
Recurring \| Level 1 \| Fair value
Assets:
Restricted cash	340	340
Total assets	75,929	30,538
Recurring \| Level 1 \| Fair value \| Cash
Assets:
Cash and cash equivalents	65,119	2,631
Recurring \| Level 1 \| Fair value \| Money market funds
Assets:
Cash and cash equivalents	10,470	27,567
Recurring \| Level 3 \| Fair value
Liabilities:
Warrants to purchase redeemable securities		1,225
Total liabilities		$ 1,225

Fair Value Measurements (Details 2) (Warrants to purchase redeemable convertible preferred stock, USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Warrants to purchase redeemable convertible preferred stock
Changes in fair value of preferred stock warrant liability
Beginning balance	$ 1,225
Change in fair value, recorded as a component of other income (expense)	1
Net exercise of warrants into common stock	$ (1,226)

Supplemental Balance Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accrued expenses
Accrued professional services	$ 3,038	$ 101
Accrued payroll and compensation	1,287	496
Accrued research and development expenses	257	422
Other accrued expenses	998	300
Total accrued expenses	$ 5,580	$ 1,319

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

Debt (Details) (USD $)	0 Months Ended	9 Months Ended		0 Months Ended						0 Months Ended				0 Months Ended
Debt (Details) (USD $)	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Jul. 11, 2014 Loan and Security Agreement [Member] tranche Lender	Sep. 30, 2014 Loan and Security Agreement [Member]	Jul. 11, 2014 Loan and Security Agreement [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] Prior To First Anniversary Of Borrowing Date [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] Prior to Second Anniversary And After First Anniversary Of Borrowing Date Member	Jul. 11, 2014 Loan and Security Agreement [Member] Prior To Maturity Date And After Second Anniversary Of Borrowing Date [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] London Interbank Offered Rate (LIBOR) [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] Tranche A [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] Tranche A [Member]	Jul. 11, 2014 Loan and Security Agreement [Member] Tranche B [Member]	Jul. 11, 2014 Previously Existing Note Agreement [Member]
Debt Instrument [Line Items]
Number of lenders				2
Maximum borrowings available						$ 30,000,000						$ 20,000,000	$ 10,000,000
Number of tranches				2
Minimum amount of draw upon closing												10,000,000
Minimum amount of draw after closing												5,000,000
Minimum net proceeds to be received from stock offering, equity raise, or strategic partner arrangement to allow for borrowing													30,000,000
Proceeds received on borrowing, net of deferred financing costs											9,800,000
Variable Interest Rate										one-month LIBOR
Basis spread (as a percent)										7.05%
Interest rate including both the variable rate and the basis spread (as a percent)					7.21%
Final fee as a percentage of original principal amount of amounts borrowed						4.75%
Minimum amount of denomination for prepayment of borrowings						1,000,000
Prepayment premium (as a percent)							1.50%	1.00%	0.50%
Effective interest rate including final fee interest and non-cash interest (as a percent)	9.44%
Repayment of notes payable		$ 3,966,000	$ 451,000											$ 2,900,000

Stockholders' Equity (Details) (USD $)	9 Months Ended		0 Months Ended
Stockholders' Equity (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Aug. 12, 2014 Over Allotment Option [Member]	Aug. 12, 2014 IPO [Member]	Aug. 12, 2014 IPO [Member]	Aug. 11, 2014 IPO [Member]	Jul. 25, 2014 IPO [Member]	Jul. 24, 2014 IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Shares issued upon completion of IPO			780,000	5,980,000
Sale price of stock (in dollars per share)					$ 11.00
Proceeds from issuance of common stock in initial public offering, net of offering costs	$ 60,145,000			$ 58,000,000
Initial public offering costs incurred but unpaid at period end	2,104,000			2,100,000
Conversion of redeemable convertible preferred stock into common stock (in shares)				12,516,298
Redeemable convertible preferred stock - Prior to conversion		112,813,000				117,400,000
Conversion of preferred stock warrants - reduction of accumulated deficit				21,000,000
Conversion of preferred stock warrants into common stock and additional paid-in capital				$ 96,400,000
Issuance of common stock upon net exercise of and reclassification of warrants to purchase redeemable convertible preferred stock (in shares)				68,700
Common stock, shares authorized	200,000,000	28,254,907			200,000,000		60,000,000	29,880,899
Preferred stock, shares authorized	10,000,000	10,000,000			10,000,000

Stockholders' Equity (Details 2) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended	9 Months Ended
Stockholders' Equity (Details 2) (USD $)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Employee Stock Purchase Plan	Sep. 30, 2014 Employee Stock Purchase Plan	Sep. 30, 2014 2006 Stock Option Plan	Dec. 31, 2013 2006 Stock Option Plan	Sep. 30, 2014 2006 Stock Option Plan Maximum [Member] Options to purchase common shares	Sep. 30, 2014 2014 Stock Option Plan Options to purchase common shares	Sep. 30, 2014 2014 Stock Option Plan Maximum [Member] Options to purchase common shares	Sep. 30, 2014 2006 and 2014 Stock Option Plans	Sep. 30, 2013 2006 and 2014 Stock Option Plans	Sep. 30, 2014 2006 and 2014 Stock Option Plans Options to purchase common shares	Sep. 30, 2013 2006 and 2014 Stock Option Plans Options to purchase common shares	Sep. 30, 2014 2006 and 2014 Stock Option Plans Minimum [Member] Options to purchase common shares	Sep. 30, 2013 2006 and 2014 Stock Option Plans Minimum [Member] Options to purchase common shares	Sep. 30, 2014 2006 and 2014 Stock Option Plans Maximum [Member] Options to purchase common shares	Sep. 30, 2013 2006 and 2014 Stock Option Plans Maximum [Member] Options to purchase common shares
Share-Based Compensation
Expiration Period									10 years		10 years
Vesting period									4 years		4 years
Shares reserved for future issuance										823,529
Shares available for grant					220,588	220,588				667,717
Percentage of common shares outstanding										4.00%
Aggregate fair value of options granted														$ 3,843,000
Percentage of full share price paid in purchase of common stock					85.00	85.00
Maximum amount of annual employee common stock purchases						25,000
Stock-based compensation expense	552,000	113,000	1,057,000	340,000	39,000	39,000
Number of Shares
Outstanding, beginning of the period (in shares)							2,265,973
Granted (in shares)												672,972
Exercised (in shares)							(63,602)
Cancelled (in shares)							(84,026)
Outstanding, end of the period (in shares)								2,265,973				2,791,317
Exercisable (in shares)							1,281,272
Vested or expected to vest (in shares)												2,433,313
Weighted Average Exercise Price Per Share
Outstanding, beginning of the period (in dollars per share)							$ 2.53
Granted (in dollars per share)												$ 11.98
Exercised (in dollars per share)							$ 2.35
Cancelled (in dollars per share							$ 2.44
Outstanding, end of the period (in dollars per share)								$ 2.53				$ 4.82
Exercisable (in dollars per share)							$ 2.24
Vested or expected to vest (in dollars per share)												$ 4.59
Weighted-Average Remaining Contractual Term (in years)
Outstanding, beginning of the period (in years)								8 years 2 months 23 days				8 years 15 days
Outstanding, end of the period (in years)								8 years 2 months 23 days				8 years 15 days
Exercisable (in years)							6 years 7 months 24 days
Vested or expected to vest (in years)												7 years 10 months 21 days
Aggregate Intrinsic Value
Outstanding, beginning of the period							11,510,000
Outstanding, end of the period								11,510,000				37,039,000
Exercisable							20,303,000
Vested or expected to vest												32,850,000
Fair value assumptions
Weighted average fair value of options granted (in dollars per share)												$ 5.71	$ 1.85
Weighted-average risk-free interest rate, minimum														1.85%	1.02%
Weighted-average risk-free interest rate, maximum														2.04%	1.78%
Expected dividend yield														0.00%	0.00%
Expected volatility, minimum														60.00%	63.00%
Expected volatility, maximum														62.00%	64.00%
Expected terms																5 years 9 months	5 years 9 months 7 days	6 years 29 days	6 years 29 days
Fair value of stock options vested							$ 812,000

Stockholders' Equity (Details 3) (USD $)	3 Months Ended		9 Months Ended
Stockholders' Equity (Details 3) (USD $)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock-based compensation expense
Stock-based compensation expense	$ 552,000	$ 113,000	$ 1,057,000	$ 340,000
Total unrecognized compensation costs related to non-vested stock options	3,889,000		3,889,000
Remaining weighted-average period that unrecognized compensation costs are expected to be recognized			3 years 2 months 12 days
Research and Development
Stock-based compensation expense
Stock-based compensation expense	127,000	37,000	250,000	117,000
Selling, General and Administrative
Stock-based compensation expense
Stock-based compensation expense	$ 425,000	$ 76,000	$ 807,000	$ 223,000

Net Loss Per Share (Details)	3 Months Ended		9 Months Ended
Net Loss Per Share (Details)	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Anti-dilutive securities
Anti-dilutive securities excluded from the computation of diluted net loss per share (in shares)	2,791,317	14,697,232	2,791,317	14,697,232
Redeemable Convertible Preferred Stock [Member]
Anti-dilutive securities
Anti-dilutive securities excluded from the computation of diluted net loss per share (in shares)		12,516,298		12,516,298
Options to purchase common shares
Anti-dilutive securities
Anti-dilutive securities excluded from the computation of diluted net loss per share (in shares)	2,791,317	2,033,450	2,791,317	2,033,450
Warrants to purchase redeemable convertible preferred stock
Anti-dilutive securities
Anti-dilutive securities excluded from the computation of diluted net loss per share (in shares)		147,484		147,484

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References+ Details

Commitments and Contingencies (Details) (Facility Expansion Lease [Member], Building [Member], USD $)	0 Months Ended
	Jul. 11, 2014 item	Jul. 11, 2014
Facility Expansion Lease [Member] \| Building [Member]
Operating Leased Assets [Line Items]
Increase in monthly base rent		$ 39,000
Number of additional terms available for extension under option	1
Renewal term	2 years