CareDx (CDNA) 10-K 29 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	CDNA
Entity Registrant Name	CareDx, Inc.
Entity Central Index Key	1,217,234
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		11,966,899
Entity Public Float			$ 48,622,431

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 29,888	$ 36,431
Accounts receivable	2,367	2,687
Inventory	766	686
Prepaid and other assets	1,341	542
Total current assets	34,362	40,346
Property and equipment, net	2,425	1,968
Intangible assets, net	6,650	6,650
Goodwill	12,005	12,005
Restricted cash	147	147
Other noncurrent assets	49	25
Total assets	55,638	61,141
Current liabilities:
Accounts payable	1,644	1,128
Accrued payroll liabilities	2,366	1,684
Accrued and other liabilities	2,892	1,616
Accrued royalties	242	241
Deferred revenue	142	505
Current portion of long-term debt	2,866	5,961
Total current liabilities	10,152	11,135
Deferred rent, net of current portion	1,426	1,684
Deferred revenue, net of current portion	703	471
Long-term debt, net of current portion	12,887	5,451
Contingent consideration	948	1,074
Other liabilities	28	28
Total liabilities	$ 26,144	$ 19,843
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock: $0.001 par value; 10,000,000 shares authorized at December 31, 2015 and 2014; no shares issued and outstanding at December 31, 2015 and 2014	$ 0	$ 0
Common stock: $0.001 par value; 100,000,000 shares authorized at December 31, 2015 and 2014; 11,902,363 and 11,803,970 shares issued and outstanding at December 31, 2015 and 2014, respectively	12	12
Additional paid-in capital	202,564	200,661
Accumulated deficit	(173,082)	(159,375)
Total stockholders’ equity	29,494	41,298
Total liabilities and stockholders’ equity	$ 55,638	$ 61,141

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	11,902,363	11,803,970
Common stock, shares outstanding	11,902,363	11,803,970

Statements of Operations

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Testing revenue	$ 27,881	$ 25,842	$ 21,672
Collaboration and license revenue	263	1,464	426
Total revenue	28,144	27,306	22,098
Operating expenses:
Cost of testing	10,273	8,541	9,078
Research and development	9,333	3,846	3,176
Sales and marketing	8,349	6,472	5,892
General and administrative	12,247	8,436	4,809
Change in estimated fair value of contingent consideration	(126)	(1,239)	0
Total operating expenses	40,076	26,056	22,955
(Loss) income from operations	(11,932)	1,250	(857)
Interest expense, net	(1,587)	(2,116)	(2,149)
Other (expense) income, net	(188)	147	(536)
Loss before income taxes	(13,707)	(719)	(3,542)
Income tax benefit	0	1,500	0
Net (loss) income	$ (13,707)	$ 781	$ (3,542)
Net (loss) income per share (Note 4):
Basic	$ (1.16)	$ 0.13	$ (3.50)
Diluted	$ (1.16)	$ 0.10	$ (3.50)
Shares used to compute net (loss) income per share:
Basic	11,860,885	5,815,928	1,010,795
Diluted	11,860,885	9,283,001	1,010,795

Statements of Convertible Prefe

Statements of Convertible Preferred Stock and Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2012	$ (147,203)	$ 135,202	$ 1	$ 9,410	$ (156,614)
Beginning Balance, Shares at Dec. 31, 2012		5,155,673	1,010,499
Issuance of common stock for cash upon exercise of stock options, Shares	212		212
Employee and non-employee share-based compensation expense	$ 72			72
Net (loss) income	(3,542)				(3,542)
Ending Balance at Dec. 31, 2013	(150,673)	$ 135,202	$ 1	9,482	(160,156)
Ending Balance, Shares at Dec. 31, 2013		5,155,673	1,010,711
Convertible preferred stock Series G issued for the acquisition of ImmuMetrix, Inc.		$ 14,242
Convertible preferred stock Series G issued for the acquisition of ImmuMetrix, Inc., Shares		888,135
Conversion of convertible preferred stock to common stock upon initial public offering	149,444	$ (149,444)	$ 6	149,438
Conversion of convertible preferred stock to common stock upon initial public offering, Shares		(6,043,808)	6,048,220
Conversion of subordinated convertible note to common stock upon initial public offering	5,108		$ 1	5,107
Conversion of subordinated convertible note to common stock upon initial public offering, Shares			510,777
Conversion of convertible preferred stock warrants to common stock warrants upon initial public offering	539			539
Issuance of common stock upon initial public offering, net of offering costs	35,511		$ 4	35,507
Issuance of common stock upon initial public offering, net of offering costs, Shares			4,220,000
Issuance of common stock for services	34			34
Issuance of common stock for services, Shares			4,899
Issuance of common stock for cash upon exercise of stock options	$ 19			19
Issuance of common stock for cash upon exercise of stock options, Shares	9,363		9,363
Employee and non-employee share-based compensation expense	$ 535			535
Net (loss) income	781				781
Ending Balance at Dec. 31, 2014	41,298		$ 12	200,661	(159,375)
Ending Balance, Shares at Dec. 31, 2014			11,803,970
Issuance of common stock for services	223			223
Issuance of common stock for services, Shares			38,121
Issuance of common stock for cash upon exercise of stock options	$ 46			46
Issuance of common stock for cash upon exercise of stock options, Shares	23,576		23,576
Issuance of common stock under employee stock purchase plan	$ 203			203
Issuance of common stock under employee stock purchase plan, Shares			36,696
Employee and non-employee share-based compensation expense	1,341			1,341
Issuance of warrants to purchase common stock in exchange for debt financing	90			90
Net (loss) income	(13,707)				(13,707)
Ending Balance at Dec. 31, 2015	$ 29,494		$ 12	$ 202,564	$ (173,082)
Ending Balance, Shares at Dec. 31, 2015			11,902,363

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net (loss) income	$ (13,707)	$ 781	$ (3,542)
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Depreciation and amortization	796	512	663
Gain on disposal of property and equipment	(2)	0	0
Stock-based compensation	1,341	535	72
Amortization of deferred revenue	(130)	(727)	(193)
Amortization of debt discount and noncash interest expense	247	799	553
Change in estimated fair value of contingent consideration	(126)	(1,239)	0
Revaluation of warrants and derivatives to estimated fair value	0	(225)	525
Non-cash income tax benefit in connection with business acquisition	0	(1,500)	0
Changes in operating assets and liabilities:
Accounts receivable	320	(417)	(1,318)
Inventory	(80)	(168)	58
Prepaid and other assets	(823)	(310)	(4)
Accounts payable	489	510	(19)
Accrued payroll liabilities	682	298	408
Accrued royalties	1	(2,563)	1,259
Deferred revenue	0	0	1,083
Accrued and other liabilities	1,240	364	(91)
Net cash used in operating activities	(9,752)	(3,350)	(546)
Investing activities:
Purchase of property and equipment	(1,199)	(733)	(98)
Payment for acquisitions, net of cash acquired	0	(600)	0
Net cash used in investing activities	(1,199)	(1,333)	(98)
Financing activities:
Proceeds from initial public offering, net of underwriters’ discount	0	39,246	0
Payments of initial public offering costs	0	(3,733)	0
Proceeds from subordinated convertible debt, net of issuance costs	0	4,982	0
Proceeds from debt, net of issuance costs	15,625	0	0
Proceeds from exercise of stock options	46	19	0
Proceeds from issuances of common stock under employee stock purchase plan	203	0	0
Principal payments on debt and capital lease obligations	(11,466)	(4,528)	(58)
Net cash provided by (used in) financing activities	4,408	35,986	(58)
Net (decrease) increase in cash and cash equivalents	(6,543)	31,303	(702)
Cash and cash equivalents at beginning of period	36,431	5,128	5,830
Cash and cash equivalents at end of period	29,888	36,431	5,128
Supplemental disclosures of cash information
Cash paid for interest	1,364	1,207	1,506
Supplemental disclosures of noncash investing and financing activities
Property and equipment purchased under capital leases	25	193	0
Common stock issued for acquisition	0	14,242	0
Conversion of convertible preferred stock to common stock upon initial public offering	0	149,444	0
Conversion of convertible preferred stock warrants to common stock warrants upon initial public offering	0	539	0
Conversion of convertible preferred stock to common stock upon initial public offering	0	5,108	0
Common stock issued in lieu of services	223	34	0
Common stock warrants issued upon debt financing	$ 90	$ 0	$ 0

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Description of Business	1. ORGANIZATION AND DESCRIPTION OF BUSINESS CareDx, Inc., (“CareDx” or the “Company”) is a molecular diagnostics company focused on the discovery, development and commercialization of clinically differentiated, high-value diagnostic surveillance solutions for transplant patients. The Company’s first commercialized testing solution, the AlloMap heart transplant molecular test (“AlloMap”), an FDA-cleared test, is a gene expression test that helps clinicians monitor and identify heart transplant recipients with stable graft function who have a low probability of moderate/severe acute cellular rejection. The Company is also pursuing the development of additional products for transplant monitoring using a variety of technologies, including AlloSure, its next-generation sequencing-based test to detect donor-derived cell-free DNA (“dd-cfDNA”) after transplantation. The Company was incorporated in Delaware in December 1998, as Hippocratic Engineering, Inc. In April 1999, the Company changed its name to BioCardia, Inc., in June 2002 to Expression Diagnostics, Inc., in July 2007 to XDx, Inc. and in March 2014 to CareDx, Inc. The Company’s operations are based in Brisbane, California and it operates in one segment. Reverse Stock Split, and Increase in Authorized Shares On July 1, 2014, the Company’s Board of Directors approved an amendment to the Company’s Certificate of Incorporation to reflect a 1 for 6.85 reverse stock split (the “Reverse Stock Split”) of the Company’s outstanding common stock and convertible preferred stock and increase the authorized common stock to 10,000,000 shares, after giving effect to the Reverse Stock Split. The Reverse Stock Split became effective July 14, 2014. The par value per share was not adjusted as a result of the Reverse Stock Split. Effective July 22, 2014, the Company’s certificate of incorporation was amended and restated to provide for 100,000,000 authorized shares of common stock with a par value of $0.001 per share, and 10,000,000 authorized shares of preferred stock with a par value of $0.001 per share. All authorized, issued and outstanding shares of common stock, convertible preferred stock, options and warrants to purchase common or preferred stock and related per share amounts contained in the financial statements have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented. Initial Public Offering On July 22, 2014, the Company closed its initial public offering (“IPO”) of 4,000,000 shares of its common stock, and issued an additional 220,000 shares of common stock on August 13, 2014 pursuant to the exercise of the over-allotment option granted to its underwriters. The public offering price of the shares sold in the offering was $10.00 per share. The total proceeds from the offering to the Company, net of underwriting discounts and commissions of $3.0 million, were $39.2 million. After deducting offering expenses payable by the Company of $3.7 million, net proceeds to the Company were $35.5 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 6,048,220 shares of common stock, and a subordinated convertible note previously issued by the Company in the principal amount of $5.0 million converted into 510,777 shares of common stock. In addition, all of the Company’s convertible preferred stock warrants were converted into warrants to purchase common stock. Liquidity and Going Concern The Company has incurred losses and negative cash flows from operations since its inception. As of December 31, 2015, the Company had cash and cash equivalents of approximately $29.9 million, and $15.8 million of debt outstanding under its debt and capital lease obligations, net of debt discount and issuance costs. Even with the Oberland Capital bridge loan, the acquisition will consume a significant portion of the Company’s current cash and cash equivalents. The Company will require additional financing to fund working capital and, within six months following entry into the bridge loan, to refinance the Oberland Capital bridge loan. The Company is pursuing financing opportunities in both the private and public debt and equity markets through sales of equity or debt securities. On August 10, 2015, the Company filed a registration statement on Form S-3 with the Securities and Exchange Commission pursuant to which it is allowed to sell equity and debt securities, subject to limitations on amount. The Company cannot initiate sales under the Form S-3 until mid-2016. Absent additional funding and assuming completion of the acquisition and entry into the bridge loan, the Company will exhaust its cash and cash equivalents in July 2016 unless the Company substantially reduces its costs and operations, including research and development and other operating costs. As a result of the Company’s obligations and lack of current available financial resources, there is uncertainty regarding the Company’s ability to maintain liquidity sufficient to operate its business effectively, which raises substantial doubt about the Company’s ability to continue as a going concern. If the Company is unsuccessful in its efforts to raise outside capital in the near term, the Company will be required to significantly reduce or cease operations. The accompanying financial statements have been prepared assuming that the Company will continue as a going concern for a period of one year December 31, 2015, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
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 accounting principles generally accepted in the United States of America (“U.S. GAAP”). Subsequent to its acquisition in 2014, the financial statements of ImmuMetrix, Inc., which was the Company’s wholly-owned subsidiary and was merged into the Company, were included in the financial statements of the Company. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to (i) revenue recognition, (ii) the differences between amounts billed and estimated receipts from payers, (iii) the determination of the accruals for clinical studies, (iv) the determination of refunds to be requested by third-party payers, (v) the fair value of assets and liabilities, (vi) the valuation of warrants to purchase convertible preferred stock, (vii) the determination of fair value of the Company’s common stock, (viii) the contingent consideration in a business acquisition, (ix) the fair value of the embedded derivative associated with the subordinated convertible note, (x) the determination of the valuation allowance and estimated tax benefit associated with deferred tax assets and net deferred tax liability, (xi) any impairment of long-lived assets including in-process technology and goodwill and (xii) legal contingencies. Actual results could differ from those estimates. Concentrations of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable. The Company’s policy is to invest its cash and cash equivalents in money market funds, obligations of U.S. government agencies and government-sponsored entities, commercial paper, and various bank deposit accounts. These financial instruments were held in Company accounts at two financial institutions. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company is exposed to credit risk in the event of default by the financial institutions to the extent of amounts recorded on the balance sheets which may be in excess of insured limits. The Company is also subject to credit risk from its accounts receivable which are derived from revenue earned from AlloMap tests provided for patients located in the U.S. and billed to various third-party payers. The Company has not experienced any significant credit losses and does not generally require collateral on receivables. For the years ended December 31, 2015, 2014 and 2013, approximately 50%, 51% and 53%, respectively, of testing revenue was paid for by Medicare. No other payers represented more than 10% of testing revenue for these periods. At December 31, 2015 and 2014, approximately 35% and 78%, respectively, of accounts receivable was due from Medicare. At December 31, 2015, approximately 21% of accounts receivable was due from Aetna. No other payer represented more than 10% of accounts receivable at December 31, 2015 or 2014. Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds. Restricted Cash Under lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements, and a surety bond. These agreements are collateralized by cash. The cash which will continue long-term to support these arrangements is classified as restricted cash on the accompanying balance sheets. Inventory Inventory is finished goods and raw materials which consist of AlloMap reagent plates, laboratory supplies and reagents. Inventories are used in connection with tests performed and may also be used for research and product development efforts. Laboratory supplies subsequently designated for research and product development use are expensed. Obsolete or damaged inventories are written off and excluded from the physical inventory. Inventories are stated at the lower of actual purchased cost determined on a first-in, first-out basis, or net realizable value. Property and Equipment, net Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets, generally three years for laboratory, computer, and office equipment, and generally seven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining lease term. Assets held under capital leases are recorded at the lower of the net present value of the minimum lease payments or the fair market value of the leased asset at the inception of the lease. Amortization expense is computed using the straight-line method over the shorter of the estimated useful lives of the assets or the period of the related lease. The Company capitalizes certain costs incurred for software developed or obtained for internal use. These costs include software licenses, consulting services, and direct materials, as well as employee payroll and payroll-related costs. Capitalized internal-use software costs are depreciated over three years. Purchased Intangible Assets Acquired intangible assets with indefinite useful lives are related to purchased in-process research and development, or IPR&D, projects and are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time. The Company tests IPR&D for impairment on an annual basis and in between annual tests if it becomes aware of any events or changes that would indicate that it is more likely than not that the fair value of the assets is below their carrying amounts. The IPR&D annual impairment test is performed as of December 1 of each fiscal year. If the fair value exceeds the carrying value, then there is no impairment. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of the asset to its carrying value, without consideration of any recoverability test. The Company has not identified any such impairment losses to date. Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. The Company has not identified any such impairment losses to date. Goodwill Goodwill represents the excess of the cost of an acquisition over the sum of the amounts assigned to tangible and identifiable intangible assets acquired, less liabilities assumed. Goodwill is not subject to amortization, but is tested for impairment on an annual basis and whenever events or changes in circumstances indicate the carrying amount of these assets may not be recoverable. The Company has determined that it operates in a single segment and has a single reporting unit associated with the development and commercialization of diagnostic products. In the event that the Company determines that it is more likely than not that the carrying value of the reporting unit is higher than its fair value, quantitative testing is performed comparing recorded values to estimated fair values. If impairment is present, it is measured as the excess of recorded goodwill over its implied fair value. The Company performs its annual evaluation of goodwill on December 1 of each fiscal year. There have been no impairments recorded to date. Fair Value of Financial Instruments Fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which the Company would transact, and it takes into consideration the assumptions that market participants would use when pricing the asset or liability. The Company’s assessment of the significance of a particular input to the fair value measurement of an asset or liability requires management to make judgments and to consider specific characteristics of that asset or liability. The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of the convertible preferred stock warrant liability and contingent consideration liability also represents their fair values. Warrants The Company had freestanding warrants enabling counterparties to purchase shares of its convertible preferred stock as of December 31, 2013, which were converted to warrants to purchase common stock on the Company’s IPO date. Freestanding warrants for convertible preferred stock that were contingently redeemable were classified as liabilities on the balance sheet and recorded at their estimated fair value. These warrants were remeasured at each balance sheet date and any change in estimated fair value was recognized in other (expense) income, net on the statements of operations. Upon the completion of the Company’s IPO in July 2014, preferred stock warrants were converted into warrants to purchase common stock, and, accordingly, the liability was reclassified to equity and became no longer subject to remeasurement. In 2015, the Company issued warrants to purchase shares of its common stock in connection with a debt financing (see Note 9). The Company accounts for these warrants as equity based on the estimated fair value of the warrants on the issuance date. The fair value of the outstanding warrants is estimated using the Black-Scholes Model. The Black-Scholes Model requires inputs such as the expected term of the warrants, expected volatility and risk-free interest rate. Certain of these inputs are subjective and require significant analysis and judgment to develop. For the estimate of the expected term, the Company uses the full remaining contractual term of the warrant. Testing Revenue The Company recognizes revenues for tests delivered when the following criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery has occurred or services rendered; (iii) the fee is fixed or determinable; and (iv) collectability is reasonably assured. The first criterion is satisfied when a third-party payer makes a coverage decision or enters into a contractual arrangement with the Company for the test. The second criterion is satisfied when the Company performs the test and delivers the test result to the ordering physician. The third criterion is satisfied if the third-party payer’s coverage decision or reimbursement contract specifies a price for the test. The fourth criterion is satisfied based on management’s judgments regarding the collectability of the fees charged under the arrangement. Such judgments include review of past payment history. AlloMap testing may be considered investigational by some payers and not covered under their reimbursement policies. Others may cover the test, but not pay a set or determinable amount. As a result, in the absence of a reimbursement agreement or sufficient payment history, collectability cannot reasonably be assured so revenue is not recognized at the time the test is delivered. If all criteria set forth above are met, revenue is recognized. When the first, third or fourth criteria are not met but third-party payers make a payment to the Company for tests performed, the Company recognizes revenue on the cash basis in the period in which the payment is received. Revenue is recognized on the accrual basis net of adjustments for differences between amounts billed and the estimated receipts from payers. The amount the Company expects to collect may be lower than the agreed upon amount due to several factors, such as the amount of patient co-payments, the existence of secondary payers and claim denials. Estimated receipts are based upon historical payment practices of payers. Differences between estimated and actual cash receipts are recorded as an adjustment to revenue, which have been immaterial to date. Taxes assessed by governmental authorities on revenue, including sales and value added taxes, are excluded from revenue in the statements of operations. Collaboration and License Revenue The Company generates revenue from collaboration and license agreements. Collaboration and license agreements may include non-refundable upfront payments, partial or complete reimbursement of research and development costs, contingent payments based on the occurrence of specified events under the agreements, license fees and royalties on sales of products or product candidates if they are successfully commercialized. The Company’s performance obligations under the collaborations may include the transfer of intellectual property rights in the form of licenses, obligations to provide research and development services and obligations to participate on certain development committees with the collaboration partners. The Company makes judgments that affect the periods over which it recognizes revenue. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any change in estimated periods of performance on a prospective basis. The Company recognizes contingent consideration received from the achievement of a substantive milestone in its entirety in the period in which the milestone is achieved, which the Company believes is more consistent with the substance of its performance under its various license and collaboration agreements. The Company did not recognize any milestones during the years ended December 31, 2015, 2014 or 2013. Cost of Testing Cost of testing reflects the aggregate costs incurred in delivering the Company’s AlloMap test results to clinicians. The components of cost of testing are materials and service costs, direct labor costs, including stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples and allocated overhead including rent, information technology, equipment depreciation and utilities and royalties. Costs associated with performing tests (except royalties) are recorded as the test is processed regardless of whether and when revenue is recognized with respect to that test. As a result, the Company’s cost of testing as a percentage of revenue may vary significantly from period to period because the Company does not recognize all revenue in the period in which the associated costs are incurred. Royalties for licensed technology, calculated as a percentage of test revenues, are recorded as license fees in cost of testing at the time the test revenues are recognized. Business Combinations The Company determines and allocates the purchase price of an acquired business to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values as of the business combination date, including identifiable intangible assets which either arise from a contractual or legal right or are separable from goodwill. The Company bases the estimated fair value of identifiable intangible assets acquired in a business combination on independent valuations that use information and assumptions provided by management, which consider management’s best estimates of inputs and assumptions that a market participant would use. The Company allocates any excess purchase price over the estimated fair value assigned to the net tangible and identifiable intangible assets acquired and liabilities assumed to goodwill. The use of alternative valuation assumptions, including estimated revenue projections, growth rates, royalty rates, cash flows, discount rates, estimated useful lives and probabilities surrounding the achievement of contingent milestones could result in different purchase price allocations and amortization expense in current and future periods. In those circumstances where an acquisition involves a contingent consideration arrangement that meets the definition of a liability under ASC 480, Distinguishing Liabilities from Equity, the Company recognizes a liability equal to the fair value of the contingent payments the Company expects to make as of the acquisition date. The Company remeasures this liability each reporting period and records changes in the fair value as a component of operating expenses. Transaction costs associated with these acquisitions are expensed as incurred in general and administrative expenses. Results of operations and cash flows of acquired companies are included in the Company’s operating results from the date of acquisition. Research and Development Expenses Research and development expenses represent costs incurred to develop new surveillance solutions as well as continued development of the Company’s AlloMap test. These expenses include payroll and related expenses, consulting expenses, laboratory supplies, and certain allocated expenses as well as amounts incurred under certain collaboration and license agreements. Research and development costs are expensed as incurred. The Company records accruals for estimated study costs comprised of work performed by contract research organizations under contract terms. Advertising Expenses All advertising costs are expensed as incurred. Advertising expenses were insignificant during all of the periods presented. Stock-based Compensation The Company uses the Black-Scholes valuation model, which requires the use of estimates such as stock price volatility and expected option lives, to value employee stock options. The Company estimates the expected option lives using historical data, volatility using data of similar companies in the diagnostics industry, and risk-free rates based on the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected option lives, and dividend yield based on the Company’s historical data. The Company uses the straight-line attribution method for recognizing compensation expense. Compensation expense is recognized on awards ultimately expected to vest and reduced for forfeitures that are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on the Company’s historical experience. Compensation expense for stock options issued to nonemployees is calculated using the Black-Scholes option pricing model and is recorded over the service performance period. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period. Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. The Company’s assessment of an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit may change as new information becomes available. Comprehensive (Loss) Income Net (loss) income and comprehensive (loss) income are the same for all periods presented. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Presentation of Financial Statements―Going Concern (Subtopic 205-40), Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern alleviate that doubt. This guidance is effective for annual periods beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted but the Company has not elected to early adopt this guidance. In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued ASU 2015-05, Intangibles—Goodwill and Other—Internal Use Software (Subtopic 350-40) In November 2015, the FASB issued ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes, In February 2016, the FASB issued ASU 2016-02, Leases,

Proposed Business Combination

Proposed Business Combination	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Proposed Business Combination Disclosure	3. PROPOSED BUSINESS COMBINATION On December 16, 2015, the Company entered into Conditional Share Purchase Agreements (“Purchase Agreements”), to acquire, subject to certain conditions approximately 78% of the outstanding shares of Allenex from its three principal shareholders in exchange for a combination of cash and CareDx common stock. On February 8, 2016, the parties entered into amendments to such Purchase Agreements to adjust the shares of CareDx common stock issuable per share of Allenex, and change the timing of distribution of cash consideration. On March 7, 2016, the Company launched a tender offer (the “Offer”), through the issuance of an Offer Document to acquire the remaining 22% of the shares of Allenex. Additionally, if CareDx acquires more than 90%, but less than 100%, of the shares of Allenex, which is necessary to initiate compulsory acquisition proceedings under Swedish laws, CareDx intends to purchase the remaining shares in Allenex for cash, pursuant to such compulsory acquisition proceedings. The Company’s Offer to the shareholders of Allenex permits such shareholders to elect either an all cash payment or a mix of cash consideration and shares of the Company’s common stock. Under the all cash alternative, the shareholders of Allenex may exchange their shares of Allenex for approximately $0.30 per share. Under the mixed consideration alternative, the shareholders of Allenex may exchange their shares of Allenex for a combination of (i) $0.20 per share and (ii) 0.01458 shares of the Company’s common stock per share. The Company anticipates completing the Offer in April 2016. If the Company acquires all Allenex shares, the total purchase price of Allenex will be approximately $35.0 million, payable in a combination of cash and CareDx common stock. If the Allenex minority shareholders accept the all cash alternative, together with the cash component payable to the three principal shareholders, the Company will distribute approximately $27.0 million in cash, excluding financial advisory, legal and accounting fees (which must be paid whether or not the acquisition is completed). If the Allenex minority shareholders elect to receive both shares and a cash payment, the Company will distribute approximately $24.6 million in cash, excluding financial advisory, legal and accounting fees (which must be paid whether or not the acquisition is completed). Allenex is a transplant diagnostics company based in Stockholm, Sweden that develops, manufactures, markets and sells products that match donor organs with potential recipients prior to transplantation. The acquisition of Allenex will create an international transplantation diagnostics company with product offerings along the pre- and post-transplant continuum. The Olerup SSP line, which addresses Human Leukocyte Antigen (“HLA”) testing, and AlloMap are foundational diagnostics which are well recognized by the transplant community. The combined company will have a presence and direct distribution channels in the US and Europe. This transaction will be accounted for as a business combination. The acquisition will require the Company to refinance or amend its existing $16.0 million debt loan with its existing lender, and the Company also expects to incur costs as it integrates Allenex’s business and operations with its own. To fund a portion of the proposed acquisition and to refinance the Company’s existing loan, in connection with the proposed acquisition, on December 15, 2015, the Companywe entered into a commitment letter and fee letter, or Commitment Letter, with Oberland Capital SA Davos LLC, collectively with its affiliates and assignees, Oberland Capital, which Commitment Letter was also amended and restated on February 8, 2016. The Commitment Letter sets forth the binding commitment, subject to the satisfaction of the conditions set forth therein, by Oberland Capital to provide a six-month bridge loan of $18.0 million, to be borrowed in connection with the closing of the acquisition. The bridge loan will mature on the date that is six months from the closing date of the bridge loan. Approximately $16.0 million of the proceeds from the bridge loan will be used to repay the Company’s outstanding loan agreement with East West Bank. Fees incurred with Oberland Capital and third parties in connection with the bridge loan are estimated to be approximately $1 million and $0 million, respectively. The loan wouldwill be secured by substantially all of the Company’s assets. The loan will bear interest at the rate of 20% per annum, and prepayments of the loan will be subject to a prepayment premium of 5% for prepayments during the first month after the closing date for the loan, decreasing by 1% each month thereafter. The loan agreement for the bridge loan wouldwill contain customary affirmative and negative covenants, financial covenants and events of default. If the Company does not perform its obligation to complete the acquisition, it may be subject to fines and penalties under Swedish law. If the Company fails to perform its obligation to close the acquisition, it may also be subject to stockholder claims for damages under the purchase agreements and under the Swedish Takeover Rules. Such penalties, fines and contract damages claims could be material and may also trigger a default under the Company’s current loan agreement, and could have other unforeseen consequences that could negatively affect its business and the price of its common stock.

Net (Loss) Income Per Share

Net (Loss) Income Per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net (Loss) Income Per Share	4. NET (LOSS) INCOME PER SHARE Basic net (loss) income per share has been computed by dividing the net (loss) income by the weighted-average number of common shares outstanding during the period, without consideration for common share equivalents. Diluted net (loss) income per share has been computed by dividing the net (loss) income by the sum of the weighted-average number of common shares and common share equivalents outstanding during the period, to the extent that such common share equivalents are dilutive. For the years ended December 31, 2015 and 2013, all common share equivalents have been excluded from the calculation of diluted net loss per share, as the effect would be antidilutive. For the year ended December 31, 2014, certain common share equivalents have been included in diluted net income per share, as their effect is dilutive. For the year ended December 31, 2014, common share equivalents include: (i) options and warrants to purchase common stock; (ii) options and warrants to purchase convertible preferred stock prior to their conversion into options and warrants to purchase common stock upon the IPO; and (iii) convertible preferred stock and the subordinated convertible note prior to their conversion into common stock upon the IPO. Common share equivalents for convertible preferred stock and the subordinated convertible note are determined using the if-converted method. Common share equivalents for options and warrants are determined using the treasury-stock method. The following tables set forth the computation of the Company’s basic and diluted net (loss) income per share (in thousands, except shares and per share data): Year Ended December 31, 2015 2014 2013 Numerator: Net (loss) income $ (13,707 ) $ 781 $ (3,542 ) Add: interest expense related to subordinated convertible note — 364 — Less: gain on change in fair value of derivative related to subordinated convertible note — (118 ) — Less: gain on extinguishment of derivative related to subordinated convertible note — (120 ) — Net (loss) income attributable to common stockholders $ (13,707 ) $ 907 $ (3,542 ) Denominator: Weighted-average shares used to compute basic net (loss) income per share attributable to common stockholders 11,860,885 5,815,928 1,010,795 Effect of potentially dilutive securities: Convertible preferred stock — 2,972,051 — Subordinated convertible note — 134,341 — Employee stock options — 360,681 — Weighted-average shares used to compute diluted net (loss) income per share attributable to common stockholders 11,860,885 9,283,001 1,010,795 Net (loss) income per share attributable to common stockholders: Basic $ (1.16 ) $ 0.13 $ (3.50 ) Diluted $ (1.16 ) $ 0.10 $ (3.50 ) The following potentially dilutive securities have been excluded from diluted net (loss) income per share, because their effect would be antidilutive: Year Ended December 31, 2015 2014 2013 Shares of common stock subject to outstanding options 1,577,317 539,645 466,965 Shares of common stock subject to outstanding common stock warrants 301,069 213,677 82,190 Shares of common stock subject to conversion from preferred stock — — 5,160,085 Shares of common stock subject to conversion from preferred stock warrants — — 541,613 Restricted stock units 106,200 — — Total common stock equivalents 1,984,586 753,322 6,250,853

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	5. FAIR VALUE MEASUREMENTS The Company records its financial assets and liabilities at fair value except for its debt, which is recorded at amortized cost. The carrying amounts of certain financial instruments of the Company, including cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. The accounting guidance for fair value provides a framework for measuring fair value, clarifies the definition of fair value, and expands disclosures regarding fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: · Level 1: Inputs which include quoted prices in active markets for identical assets and liabilities. · Level 2: Inputs other than Level I that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. · Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis, as of December 31, 2015 and 2014 (in thousands): December 31, 2015 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 28,774 $ — $ — $ 28,774 Liabilities Contingent consideration $ — $ — $ 948 $ 948 December 31, 2014 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 36,779 $ — $ — $ 36,779 Liabilities Contingent consideration $ — $ — $ 1,074 $ 1,074 The following table presents the issuances, changes in fair value and reclassifications of the Company’s Level 3 financial instruments that are measured at fair value on a recurring basis (in thousands): (Level 3) Contingent Consideration Liability Warrants to Purchase Convertible Preferred Stock Derivative Liability Related to Subordinated Convertible Note Total Balance as of December 31, 2013 $ — $ 525 $ — $ 525 Issuance of financial instruments 2,313 — 239 2,552 Change in estimated fair value (1,239 ) 14 (239 ) (1,464 ) Reclassification to stockholders' equity — (539 ) (539 ) Balance as of December 31, 2014 1,074 — — 1,074 Change in estimated fair value (126 ) (126 ) Balance as of December 31, 2015 $ 948 $ — $ — $ 948 The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers between Level 1, Level 2 and Level 3 categories during the periods presented. In determining fair value, the Company uses various valuation approaches within the fair value measurement framework. The valuation methodologies used for the Company’s instruments measured at fair value and their classification in the valuation hierarchy are summarized below: · Money market funds —Investments in money market funds are classified within Level 1. At December 31, 2015 and 2014, money market funds were included on the balance sheets in cash and cash equivalents. · Contingent consideration —As of December 31, 2015, the Company had a contingent obligation to issue 227,845 shares of the Company’s common stock to the former owners of ImmuMetrix, Inc. in conjunction with the Company’s acquisition of ImmuMetrix, Inc. (see Note 14). The issuance will occur if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020. The Company recorded its estimate of the fair value of the contingent consideration based on its evaluation of the probability of the achievement of the contractual conditions that would result in the payment of the contingent consideration. The fair value of the contingent consideration was estimated using the fair value of the shares to be paid if the contingency is met multiplied by management’s 65% estimate at December 31, 2015 and 2014 of the probability of success. The significant input in the Level 3 measurement not supported by market activity is the Company’s probability assessment of the milestone being met. The value of the liability is subsequently remeasured to fair value each reporting date, and the change in estimated fair value is recorded to the operating expense item captioned “change in estimated fair value of contingent consideration” until the milestone contingency is paid, expires or is no longer achievable. Increases (decreases) in the estimation of the probability percentage result in a directionally similar impact to the fair value measurement of the contingent consideration liability. · Warrants to purchase convertible preferred stock —Prior to the Company’s IPO, its warrants to purchase convertible preferred stock were classified as Level 3 because they were valued based on unobservable inputs and management’s judgment due to the absence of quoted market prices, inherent lack of liquidity and the long-term nature of such financial instruments. These assumptions are inherently subjective and involve significant management judgment. The significant unobservable input used in the fair value measurement of the warrant liability was the fair value of the underlying convertible preferred stock at the valuation remeasurement date. Generally, increases (decreases) in the fair value of the underlying stock would result in a directionally similar impact to the fair value measurement of the preferred stock warrants. Any change in estimated fair value is recognized in other expense (income), net on the statements of operations. Upon the Company’s IPO in July 2014, certain warrants to purchase convertible preferred stock were converted into warrants to purchase common stock and were reclassified to equity, while other warrants to purchase preferred stock expired pursuant to their terms. · Derivative liability related to subordinated convertible note —On April 17, 2014, the Company issued a $5.0 million subordinated convertible promissory note to Illumina, Inc. that had some features that constituted embedded derivatives. The Company determined that the optional conversion or repayment upon a change in control is an equity call option with a potentially variable value to be received and meets the definition of a derivative which would be required to be bifurcated. The estimated fair value of this embedded derivative was affected by the estimated probability assigned to the various scenarios for the host instrument. As of April 17, 2014, management estimated repayment upon a change in control within the loan term at a 10% probability. The estimated fair value of the embedded derivative liability of $239,000 as of April 17, 2014 was included in accrued and other liabilities. Upon the Company’s IPO in July 2014, the subordinated convertible note was converted into common stock, and so the embedded conversion option was extinguished. Accordingly, the fair value of the derivative became $0, and a gain of $239,000 was recorded in other (expense) income, net. The significant unobservable input used in the fair value measurement of the derivative liability was the probability assigned to the various scenarios. Generally, increases (decreases) in the probability of the factors primarily impacting the valuation would result in a directionally similar impact to the fair value measurement of the derivative liability. Changes in estimated fair value were recognized in other (expense) income, net on the statements of operations. The Company’s liabilities classified as Level 3 were valued based on unobservable inputs and management’s judgment due to the absence of quoted market prices, inherent lack of liquidity and the long-term nature of the financial instruments. The carrying values of the Company’s debt approximate their fair values at December 31, 2015 and 2014 as the market rates currently available to the Company and other assumptions have not changed significantly.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	6. BALANCE SHEET COMPONENTS Inventory Inventory consisted of the following (in thousands): December 31, 2015 2014 Finished goods $ 237 $ 277 Raw materials 529 409 Total inventory $ 766 $ 686 Property and Equipment, Net Property and equipment consisted of the following (in thousands): December 31, 2015 2014 Laboratory equipment $ 5,022 $ 4,392 Leasehold improvements 4,326 4,040 Furniture and fixtures 825 825 Computer and office equipment 4,125 3,775 Construction-in-process — 28 14,298 13,060 Less: Accumulated depreciation and amortization (11,873 ) (11,092 ) Property and equipment, net $ 2,425 $ 1,968 Depreciation and amortization expense was $0.8 million, $0.5 million and $0.7 million for the years ended December 31, 2015, 2014 and 2013, respectively. Assets purchased under capital leases, included above in laboratory equipment, computer and office equipment, were $1.7 million and $1.6 million at December 31, 2015 and 2014, respectively. Accumulated amortization was $1.5 million at December 31, 2015 and 2014. Related amortization expense, included in depreciation and amortization expense, was $79,000, $59,000 and $26,000 for the years ended December 31, 2015, 2014 and 2013, respectively. Accrued and Other Liabilities Accrued and other liabilities consisted of the following (in thousands): December 31, 2015 2014 Professional fees $ 880 $ 273 Test sample processing fees 426 318 Accrued overpayments and refunds 163 146 Clinical studies 756 144 Deferred rent – current portion 258 202 Capital leases – current portion 71 70 Other accrued expenses 338 463 Total accrued and other liabilities $ 2,892 $ 1,616

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. COMMITMENTS AND CONTINGENCIES Leases The Company leases its laboratory and office facility in Brisbane, California, under a non-cancelable operating lease agreement expiring in December 2020. The terms of the facility lease provide for rental payments on a graduated scale. The Company recognizes rent expense on a straight-line basis over the lease period and has accrued for rent expense incurred but not paid. In addition, incentives were granted, including allowances to fund leasehold improvements and rent holidays. As such, these allowances have been recorded as deferred rent, and these items are being recognized as reductions to rental expense on a straight-line basis over the term of the lease. During 2013, the Company had leases for blood draw centers under non-cancelable operating leases. Although the Company had subleased some of the blood draw center properties, it remained obligated under the original operating leases. The final lease payment related to the blood draw centers was made in August 2013. Rent expense under the non-cancelable operating leases was $1.0 million in 2015, 2014 and 2013. Future minimum lease commitments under these operating and capital leases at December 31, 2015, are as follows (in thousands): Years ending December 31, Capital Leases Operating leases 2016 $ 75 $ 1,291 2017 55 1,348 2018 16 1,376 2019 5 1,404 2020 and thereafter — 1,432 Total minimum lease payments 151 $ 6,851 Less: amounts representing interest (23 ) Present value of minimum lease payments 128 Less: current portion of obligations under capital leases (71 ) Long-term portion of obligations under capital leases $ 57 The current portion of obligations under capital leases is included in accrued and other liabilities on the balance sheets. The long-term portion is included in long-term debt, net of current portion on the balance sheets. See Note 9 for the aggregate annual payment schedule for the Company’s outstanding venture debt. Royalty Commitments In November 2004, the Company entered into a license agreement with Roche Molecular Systems, Inc., or Roche, that grants the Company the right to use certain Roche technology relating to polymerase chain reaction, or PCR, and quantitative real-time PCR, in clinical laboratory services, including in connection with AlloMap. This is a non-exclusive license agreement in the United States covering claims in multiple Roche patents. The Company had disputed the combination services percentage Roche sought to apply under the agreement. The combination service percentage is a multiplier used to calculate royalties where licensed services are sold in combination with other services. From July 2011 through September 2014, the Company withheld payment of such royalties pending resolution of the matter. On February 11, 2014, Roche filed a demand for arbitration with the American Arbitration Association seeking a declaration that the Company had materially breached the Roche license agreement by failing to report and pay royalties owing to Roche in respect of licensed services performed by the Company after July 1, 2011. Since July 1, 2011, the Company fully accrued the unpaid royalties on the balance sheets, and the amount of the unpaid royalties has been reflected as an expense in the Company’s income statements in the periods to which the royalties relate. In September 2014, the Company entered into a settlement and mutual release agreement with Roche whereby: (i) for the period beginning July 1, 2011 through June 30, 2014, the Company agreed to pay the amount of $2,827,220 in settlement of past royalties due; (ii) for the period beginning July 1, 2014 through September 30, 2014, the Company agreed to pay royalties based on the same combination services percentage used to determine the past royalties due; (iii) for the period beginning October 1, 2014 through September 30, 2017, Roche and the Company agreed to a downward adjustment of the combination services percentage used to determine the portion of the AlloMap testing revenue that is royalty bearing under the terms of the license; (iv) the Company agreed to report and pay quarterly royalties within 45 days of the end of each calendar quarter; (v) Roche agreed that, subject to the Company’s timely payment of all applicable royalties through such date, no further royalties will be payable by the Company for periods after September 30, 2017; (vi) the Company and Roche agreed to mutually release all claims under the license agreement through the settlement date; and (vii) Roche agreed to dismiss the arbitration claims. For all time periods, the contractual royalty rate in the license agreement was or will be applied to the applicable combination services percentage to determine the royalties payable for the AlloMap service. Under the license agreement, the Company incurs royalty expenses as a percentage of combination services revenue and classifies those expenses as a component of cost of testing in the statements of operations. As a result of the Company’s September 2014 settlement and payment to Roche of $2.8 million as payment in full of all royalties under the license agreement from July 1, 2011 through June 30, 2014, the Company recorded a reduction of $0.6 million to cost of testing and $0.1 million to interest expense in the statements of operations for the year ended December 31, 2014. Of the $2.8 million paid by the Company under the terms of the settlement agreement, $0.4 million represented royalties on AlloMap revenue for the six months ended December 31, 2011, $0.9 million represented royalties on AlloMap revenue for the year ended December 31, 2012, $1.0 million represented royalties on AlloMap revenue for the year ended December 31, 2013, and $0.6 million represented royalties on AlloMap revenue for the year ended December 31, 2014. For the years ended December 31, 2015, 2014 and 2013, royalty expenses in connection with the Roche agreement were $1.0 million, $0.7 million and $1.2 million, respectively. Contingencies The Company is subject to claims and assessments from time to time in the ordinary course of business. The Company’s management does not believe that any such matters, individually or in the aggregate, will have a material adverse effect on the Company’s business, financial condition, or results of operations.

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and Licensing Agreements	8. COLLABORATION AND LICENSING AGREEMENTS Laboratory Corporation of America Holdings (“LabCorp”) In April 2012, CareDx and LabCorp entered into a collaboration and license agreement (“2012 Agreement”) to develop a lupus flare predictor test. The agreement provided for CareDx to license technology to LabCorp. Of the total arrangement consideration, the fair value of the license was assessed to be $1.0 million. The license term in the 2012 Agreement was the later of 10 years from the date of the agreement or the expiration of the last-to-expire patents and patent applications included in the CareDx technology licensed to LabCorp, unless the license were terminated by mutual agreement. The agreement provided that CareDx and LabCorp would share equally the costs of developing the lupus flare predictor test; however LabCorp’s share of the development cost was subject to certain limits at each stage of the arrangement. Under the agreement, in 2012 LabCorp paid the Company a nonrefundable and non-creditable upfront license fee payment of $1,000,000, and a nonrefundable and non-creditable payment of $250,000 for certain lupus samples. The Company was to receive royalties in the high single digits from LabCorp on net sales of the commercialized flare predictor test or other tests developed using the samples sold. Phase 1 of the project was completed in the first quarter of 2014. On September 18, 2014, CareDx and LabCorp terminated the 2012 agreement. The termination agreement provides that: · CareDx transfer and assign to LabCorp, 300 “SAGE I” clinical samples and related clinical data and documentation that CareDx obtained from patients during the discovery phase of the collaboration; · CareDx grant a perpetual, non-exclusive worldwide, fully paid, sublicensable, royalty-free license to use any collaboration intellectual property and data for any and all purposes; and · LabCorp pay $500,000 to CareDx within 30 days of CareDx’s delivery of the clinical samples and clinical data and documentation. No further royalties, milestone fees or other fees will be payable by LabCorp after the termination date. During the three months ended December 31, 2014, the Company delivered the clinical samples and the related clinical data and documentation to LabCorp, and accordingly recognized the $500,000 termination fee and the remaining $611,000 previously unrecognized license fee. During the years ended December 31, 2014 and 2013, the Company recognized $1.1 million and $328,000, respectively, in revenue under this arrangement, which consisted of amortization of the upfront license fee of $626,000 and $187,000, respectively, reimbursement of research and development expenses of $16,000 and $141,000, respectively, and a collaboration termination fee of $500,000 and $0, respectively. Such revenues are included in collaboration and license revenue on the statements of operations. No revenues were recognized during the year ended December 31, 2015. Included in research and development expenses were $32,000 and $282,000 for the years ended December 31, 2014 and 2013, respectively, for development costs associated with the 2012 Agreement. No research and development expenses were recorded for the year ended December 31, 2015. Diaxonhit (“DHT”) In June 2013, the Company entered into an exclusive Distribution and Licensing Agreement with DHT, a French public company, whereby DHT will have the AlloMap test performed in a European laboratory and commercialize the test in the European Economic Area (“EEA”). The agreement will expire at the later of the last-to-expire patent in the EEA or ten years from the first commercial sale of the test in the EEA, which occurred in 2014. Consideration under the agreement includes an upfront cash payment of approximately €387,500 ($503,000) that is designated to offset royalties earned by the Company in the first three years following the first commercial sale. The Company is entitled to receive royalties from DHT as a percent of net sales, as defined in the agreement, of AlloMap tests in the mid to high teens. Approximately €250,000 ($344,000) of the upfront payments is refundable under certain circumstances. Upon confirmation that the CE mark was in place, the Company also received an equity payment of DHT common stock with a value of €387,500 ($503,000). The CE mark is a mandatory conformity marking for certain products sold within the EEA. These shares were promptly sold by the Company in July 2013 for total consideration of $467,000. Other consideration that may be earned by the Company includes agreed-upon per unit pricing for the supply of AlloMap products, and additional royalties that are payable upon the achievement of various sales milestones by DHT. In this arrangement, there is one combined unit of accounting. Commercial sales began in the EEA in June 2014. Total revenue recognized from this arrangement for the years ended December 31, 2015 and 2014 was $46,000 and $36,000, respectively. CardioDx, Inc. (“CDX”) In 2005, the Company entered into a services agreement with what at the time was a related party, CDX, whereby the Company provided CDX with biological samples and related data and performed laboratory services on behalf of CDX. Each company granted the other a worldwide license under certain of its intellectual property rights. Pursuant to this agreement, CDX pays royalties to the Company of a low single-digit percentage of the cash collected from sales of CDX licensed products. In 2009, CDX terminated the services portion of this agreement, however, the royalty obligation from CDX continues until the tenth anniversary of the first commercial sale of a CDX licensed product. The first commercial sale of such product by CDX occurred in 2009, therefore the royalty obligation to the Company continues until 2019. Royalty revenues, recorded when earned, were $179,000, $221,000 and $94,000 for the years ended December 31, 2015, 2014 and 2013, respectively, and are included in collaboration and license revenue on the statements of operations. Starting in the fourth quarter of 2015, the Company changed its accounting for royalty revenues from CDX from accrual basis to cash basis. The Company had receivable balances from CDX of $0 and $54,000 at December 31, 2015 and 2014, respectively.

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Transfers And Servicing [Abstract]
Debt	9. DEBT Venture Debt In August 2012, the Company entered into a $15,000,000 loan and security agreement (the “2012 Loan”), and repaid a loan entered into in 2010 (the “2010 Loan”) including principal of $10,333,833, a termination fee of $875,000, and other costs associated with the payoff. Prepayment penalties and write-off of the remaining unamortized costs associated with the 2010 Loan resulted in a charge to interest expense of approximately $628,000 during the year ended December 31, 2012. These transactions generated net cash proceeds to the Company of $3,432,260. In August 2013, the Company amended the 2012 Loan to defer the beginning of repaying principal for six months, to March 1, 2014. To obtain this deferral, there was an additional fee of $150,000 due at the end of the loan term. The 2012 Loan, as amended, provided for interest-only payments for 18 months followed by 30 equal monthly principal and interest payments of $566,822 at an annual interest rate of 9.95%. In addition, a final payment of $1,275,000 was to be due at the end of the loan term. The 2012 Loan also included a facility fee of $75,000. In connection with the 2012 Loan, the Company issued to the lenders warrants to purchase 167,182 shares of Series G convertible preferred stock or Next Round Stock at $21.78 per share. The warrants are exercisable until 2019. The estimated fair value of warrants on the date of issuance was negligible. The estimated fair value of the warrants at December 31, 2013, including the methodology and input assumptions used in the valuation, is discussed in Note 9. On July 22, 2014, upon the completion of the Company’s IPO, the warrants converted into warrants to purchase common stock. The 2012 Loan was collateralized by a security interest in all of the Company’s assets except intellectual property on which there is a negative pledge, and the loan agreement contained covenants, including a revenue covenant, and restrictions on the Company’s ability to pay cash dividends. At December 31, 2014, the Company was in compliance with all loan covenants. In connection with the 2010 Loan, the Company issued to the lenders warrants to purchase 17,215 shares of Series G convertible preferred stock at $21.78 per share. The warrants were exercisable until 2017. The estimated fair value of the warrants on the date of issuance of $8,000 was recorded as a debt discount liability which was being amortized to interest expense over the term of the loan. On July 22, 2014, upon the completion of the Company’s IPO, the warrants converted into warrants to purchase common stock. The $11.3 million outstanding balance of the 2012 Loan was paid off with proceeds from the secured term loan facility that the Company entered into on January 30, 2015. Subordinated Convertible Note On April 17, 2014, the Company issued a $5.0 million Subordinated Convertible Promissory Note to Illumina, Inc. (the “2014 Note”) which provided for interest at an annual rate of 8.0%. The 2014 Note was to mature one year following its issuance with principal and unpaid interest due at that time unless the Note were converted into equity prior to the maturity date. As described below, conversion was mandatory in the event of a Qualified Initial Public Offering. Upon the closing of the IPO on July 22, 2014, the 2014 Note converted into 510,777 shares of common stock in accordance with its terms. The original estimated fair value of a certain embedded derivative was accounted for as a debt discount to the subordinated convertible note payable on the balance sheet. The estimated fair value of the embedded derivative liability was included in accrued and other liabilities on the balance sheets. Amortization of the debt discount was $256,000 for the period from April 17, 2014 to July 22, 2014, when the 2014 Note was converted into common stock. Extinguishment of the embedded derivative liability at July 22, 2014 resulted in other income of $120,000. Secured Term Loan Facility On January 30, 2015, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) which provides a secured term loan facility in an aggregate principal amount of up to $20.0 million. The Company borrowed the first and only advance of $16.0 million (“Draw A”) on January 30, 2015. Draw A was used to pay-off the Company’s existing term debt of $11.3 million. A loss on extinguishment of $0.6 million from the pay-off of the existing term loan was recognized as interest expense for the year ended December 31, 2015. Draw A bears interest at a daily floating rate equal to 2.00%, plus the greater of (i) 3.25% or (ii) the prime rate published by the lender. The maturity date of the loan is December 1, 2018. Principal pay-down of the loan begins on January 1, 2016 with the loan being payable in 36 equal installments. The principal pay-down of the loan may be delayed to July 1, 2016 with the loan being payable in 30 equal monthly installments, if on December 31, 2015, the Company has achieved certain net product revenue milestones as described in the Loan Agreement. As of December 31, 2015, the Company was in compliance with its net product revenue milestones, which allows the Company to pay only the interest incurred on a monthly basis until June 30, 2016 and begin the principal pay-down on July 1, 2016. A fully non-refundable commitment fee of $160,000 was paid on January 30, 2015 when Draw A for $16.0 million was received. The loan has no prepayment penalty. Commitment fees are included in debt issuance costs which are amortized to interest expense using the effective interest method over the term of the loan. Debt discount and issuance costs, current, as of December 31, 2015 and 2014 were $155,000 and $76,000, respectively. Debt discount and issuance costs, non-current, as of December 31, 2015 and 2014 were $149,000 and $11,000, respectively. The debt discount and issuance costs are reported in the balance sheet as a direct reduction from the carrying amount of the debt liability. In connection with the Loan Agreement, the Company agreed to issue to the lender a detachable warrant to purchase shares of the Company’s common stock upon the drawdown of each advance in an amount equal to 1.5% of the amount drawn, divided by the exercise price per share for that tranche. The fair value of the warrant is reflected as a discount to the debt. As a result of Draw A, the Company issued to the lender a warrant to purchase an aggregate of 34,483 shares of the Company’s common stock, at an exercise price of $6.96 per share. The fair value of the warrant was estimated to be approximately $90,000 on January 30, 2015, using the Black-Scholes Model with the following assumptions: expected volatility of 39.83%, a contractual term of 5 years, risk-free interest rate of 1.18%, underlying common stock price of $7.06, and dividend yield of 0%. The warrant is included in stockholders’ equity with the offset to debt discount that is amortized over the term of the loan using the effective interest method. The warrant is not subject to remeasurement. The Loan Agreement requires collateral by a security interest in all of the Company’s assets except intellectual property and contains customary affirmative and negative covenants including financial maintenance covenants, and also includes standard events of default, including payment defaults. Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and the lender may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Loan Agreement. At December 31, 2015, the Company was in compliance with all loan covenants. Aggregate annual payments, net of interest, at December 31, 2015 due on the Loan Agreement are as follows (in thousands): Year ending December 31: Annual Payments 2016 $ 3,021 2017 6,309 2018 6,670 16,000 Less: debt discount and issuance costs (304 ) 15,696 Less: current portion, net of debt discount and issuance costs (2,866 ) Long-term portion, net of debt discount and issuance costs $ 12,830

Warrants

Warrants	12 Months Ended
	Dec. 31, 2015
Warrants [Abstract]
Warrants	10. WARRANTS At December 31, 2015, outstanding common stock warrants consisted of: Original Term Exercise Price Number of Shares Underlying Warrants Original issue date: July 2006 10 years $ 31.72 17,656 November 2006 10 years $ 31.72 1,576 February 2008 10 years $ 35.07 22,792 August 2009 10 years $ 21.78 33,472 July 2010 9 years $ 21.78 6,694 January 2015 5 years $ 6.96 34,483 116,673

Stock Incentive Plans

Stock Incentive Plans	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	11. STOCK INCENTIVE PLANS Stock Option Plans Prior to its IPO in July 2014, the Company had one active stock option plan, the 2008 Equity Incentive Plan (“2008 Plan”), one assumed stock option plan (the ImmuMetrix 2013 Equity Incentive Plan) and one terminated stock option plan, the 1998 Stock Plan. Upon its IPO, the Company reserved 838,695 shares of common stock for issuance under a new 2014 Equity Incentive Plan (“2014 Plan”). The shares reserved for issuance under the 2014 Plan also include shares returned to the 2008 Plan as the result of expiration or termination of options, provided that the maximum number of shares that may be added to the 2014 Plan thereby is limited to a maximum of 865,252 shares. The number of shares available for issuance under the 2014 Plan will also include an annual increase on the first day of each year beginning in 2014, equal to the least of: · 357,075 shares; · 4.0% of the outstanding shares of common stock as of the last day of the immediately preceding year; or · such other number of shares as the Company’s board of directors may determine. Stock Options The following table summarizes option activity under the plans, and related information: Shares Available for Grant Stock Options Outstanding Weighted- average Exercise Price Balance—December 31, 2012 180,266 619,906 $ 2.67 Granted (4,081 ) 4,081 0.48 Exercised — (212 ) 0.55 Forfeited 7,247 (7,247 ) 2.33 Expired 149,563 (149,563 ) 4.73 Balance—December 31, 2013 332,995 466,965 1.99 Additional options authorized 940,884 — — Granted (585,345 ) 585,345 11.76 Assumed in business combination — 23,229 2.06 Exercised — (9,363 ) 2.14 Forfeited 20,591 (20,591 ) 10.36 Expired 13,781 (13,781 ) 2.74 Balance—December 31, 2014 722,906 1,031,804 7.36 Additional options authorized 357,075 — — Granted (652,078 ) 652,078 6.09 Exercised — (23,576 ) 1.94 Forfeited 77,660 (77,660 ) 8.13 Expired 5,329 (5,329 ) 10.36 Balance—December 31, 2015 510,892 1,577,317 6.87 The total intrinsic value of options exercised was approximately $89,000 during 2015. Outstanding, exercisable and vested stock options as of December 31, 2015 are summarized as follows: Option s Options Vested at December 31, 2015 Range of Exercise Prices Number of Options Outstanding Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Number of Options Weighted Average Exercise Price $0.27 - 0.56 193,581 6.80 $ 0.55 166,699 $ 0.55 $2.05 - 3.06 135,656 5.88 2.83 135,656 2.83 $3.36 - 6.98 716,157 8.28 5.68 127,859 3.84 $7.03 - 12.44 531,923 8.38 11.80 249,779 11.79 1,577,317 7.92 6.87 679,993 5.75 Options outstanding that have vested and are expected to vest at December 31, 2015 are as follows: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual (Years) Aggregate Intrinsic Value (In Vested 679,993 $ 5.75 6.58 $ 1,788 Expected to Vest 897,324 7.71 8.95 $ 435 Total 1,577,317 6.87 7.92 $ 2,223 The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company’s common stock at December 31, 2015 for stock options that were in-the-money. The fair market value of the Company’s common stock as of December 31, 2015 was $6.40 per share. The weighted average grant-date fair value of options to purchase common stock granted for the years ended December 31, 2015, 2014 and 2013 using the Black-Sholes valuation model was $2.53, $4.81 and $0.21, respectively. The Company uses the grant date fair value of its common stock to value both employee and non-employee options when granted. The Company revalues non-employee options each reporting period using the fair market value of the Company’s common stock as of the last day of each reporting period. The total fair value of options that vested during 2015 was $1.1 million. As of December 31, 2015, there was approximately $10.2 million of unrecognized stock-based compensation, net of estimated forfeitures, related to non-vested stock options that will be recognized on a straight-line basis over the remaining average vesting period of 2.8 years. 2014 Employee Stock Purchase Plan The Company’s board of directors adopted its 2014 Employee Stock Purchase Plan (the “ESPP”) in March 2014 and its stock holders approved the ESPP in July 2014. However, the Company’s ESPP was not made available to its employees until January 1, 2015. The first offering period of the ESPP began on January 1, 2015 and ended June 30, 2015. Under the first offering period, 36,696 shares were purchased. The second offering period began July 1, 2015 and ended December 31, 2015. Under the second offering period, 32,232 shares were purchased. At December 31, 2015, the proceeds from the issuance of shares were $0.4 million and a total of 186,473 shares of the Company’s common stock is available for sale under the ESPP. The option price per share of common stock to be paid by a participant upon exercise of the participant’s option on the applicable exercise date for an offering period shall be equal to 85% of the lesser of the fair market value of a share of common stock on (a) the applicable grant date or (b) the applicable exercise date. Valuation Assumptions The Company’s board of directors determines the estimated fair value of the Company’s common stock based on assistance from an independent third party valuation firm. The fair value of employee stock options and ESPP was estimated using the Black-Scholes option-pricing model using the following weighted-average assumptions. Year Ended December 31, 2015 2014 2013 Employee Stock Options Expected term (in years) 6.0 5.1 6.0 Expected volatility 41.17 % 42.18 % 45.25 % Risk-free interest rate 1.84 % 1.69 % 1.21 % Expected dividend yield — % — % — % Employee Stock Purchase Plan Expected term (in years) 0.5 — — Expected volatility 39.10 – — — Risk-free interest rate 0.11 % — — Expected dividend yield — % — % — % Risk-free Interest Rate: The Company based the risk-free interest rate over the expected term of the award based on the constant maturity rate of U. S. Treasury securities with similar maturities as of the date of grant. Volatility: The Company used an average historical stock price volatility of comparable public companies that were deemed to be representative of future stock price trends as the Company does not have sufficient trading history for its common stock. Expected Term: The expected term represents the period for which the Company’s stock-based awards are expected to be outstanding and is based on analyzing the vesting and contractual terms of the awards and the holders’ historical exercise patterns and termination behavior. Expected Dividends: The Company has not paid and does not anticipate paying any dividends in the near future. Restricted Stock Units The Company’s 2014 Plan allows restricted stock units (“RSUs”) to be granted in addition to stock options. The RSUs vest annually over four years in equal increments. RSUs were granted by the Company for the first time in March 2015. Unvested RSU activity for the year ended December 31, 2015 is summarized below: Number of Shares Weighted- Average Grant Date Fair Value Unvested balance at December 31, 2014 — $ — Granted 114,400 6.49 Vested — — Forfeited (8,200 ) 6.49 Unvested balance at December 31, 2015 106,200 6.49 As of December 31, 2015, there was approximately $2.4 million of unrecognized stock-based compensation, net of estimated forfeitures, related to non-vested RSUs that will be recognized on a straight-line basis over the remaining average vesting period of 3.0 years. The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs, and ESPP for the years ended December 31, 2015, 2014 and 2013, included in the statements of operations as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of testing $ 109 $ 28 $ 3 Research and development 247 88 7 Sales and marketing 173 29 3 General and administrative 812 390 59 $ 1,341 $ 535 $ 72 No tax benefit was recognized related to share-based compensation expense since the Company has never reported taxable income and has established a full valuation allowance to offset all of the potential tax benefits associated with its deferred tax assets. In addition, no amounts of share-based compensation costs were capitalized for the periods presented. Non-Employee Director Equity-based Compensation For the years ended December 31, 2015 and 2014, the Company paid a portion of its non-employee directors’ compensation through the award of common shares. The stock awards are classified as equity, and compensation expense was recognized upon the issuance of the shares. As of December 31, 2015, there was a total of 57,543 shares issued to non-employee directors, for a total fair value of $349,000. Expense associated with the awards was $255,000 and $94,000 for the years ended December 31, 2015 and 2014, respectively, which was included in general and administrative expense in the statements of operations.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	12. INCOME TAXES The Company generated pretax net losses of $13.7 million, $0.7 million and $3.5 million for the years ended December 31, 2015, 2014 and 2013, respectively. The Company recorded no benefit for income taxes for 2015. For 2014, the Company recorded a federal and state deferred tax benefit of $1.5 million and $0, respectively, and no benefit for income taxes was recorded for 2013. A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows: Year Ended December, 31, 2015 2014 2013 Federal tax at statutory rate 34.0 % 34.0 % 34.0 % Stock-based compensation -1.9 % -9.5 % -11.4 % Change in valuation allowance -31.1 % 190.6 % -8.6 % Change in unrecognized tax benefits 0.0 % 0.0 % -8.4 % Preferred stock warrant revaluation 0.0 % -0.7 % -5.0 % Interest expense 0.0 % -5.8 % 0.0 % Contingent liability for IMX acquisition 0.0 % 38.2 % 0.0 % Acquisition costs -3.2 % -36.7 % 0.0 % Other 2.2 % -1.3 % -0.6 % Effective income tax rate 0.0 % 208.8 % 0.0 % In connection with the Company’s June 2014 acquisition of ImmuMetrix, Inc. (“IMX”), a tax benefit of $1.5 million was recognized during the year ended December 31, 2014. This benefit resulted from the expectation that amortization of the in-process technology acquired, when completed and placed in service, is not expected to be deductible for tax purposes, as the transaction was structured as a tax-free reorganization. Accordingly, a deferred tax liability was recorded at the acquisition date for the difference between the financial reporting and tax basis of the acquired in-process technology. While the in-process technology is considered an indefinite lived intangible asset, this asset is expected to be amortized or impaired prior to the expiration of net operating loss carryforwards available to the Company. As a result of recording this deferred tax liability the company’s valuation allowance was reduced by an equal amount. The tax effects of temporary differences and carryforwards that give rise to significant deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 65,957 $ 63,116 Tax credit carryforwards 4,533 4,065 Accruals 1,125 942 Other 698 551 Gross deferred tax assets 72,313 68,674 Deferred tax liabilities: Property and equipment 95 (8 ) Purchased intangibles (2,355 ) (2,349 ) Total deferred tax liabilities (2,260 ) (2,357 ) Valuation allowance (70,053 ) (66,317 ) Net deferred tax assets $ — $ — The Company has recorded pretax net losses from operations since its inception. The Company believes that based on the history of such losses and other factors, the weight of available evidence indicates that it is more likely than not that it will not be able to realize its net deferred tax assets. Accordingly, the net deferred tax assets have been offset by a full valuation allowance. The valuation allowance increased by $3.7 million and decreased by $1.9 million during the years ended December 31, 2015 and 2014, respectively. As of December 31, 2015, the Company had net operating loss carryforwards of approximately $174.3 million and $115.9 million available to reduce future taxable income, if any, for federal and state income tax purposes, respectively. The U.S. federal net operating loss carryforwards will begin to expire in 2018 while for state purposes, the net operating losses will begin to expire in 2016. As of December 31, 2015, the Company had credit carryforwards of approximately $3.6 million and $4.4 million available to reduce future taxable income, if any, for federal and California state income tax purposes, respectively. The Federal credit carryforwards begin to expire in 2021. California credits have no expiration date. Utilization of the Company’s net operating loss carryforwards and credits may be subject to a substantial annual limitation due to the ownership change limitations provided by the Tax Reform Act of 1986, as amended and similar state provisions. The annual limitation may result in the expiration of net operating losses and credits before utilization. Based on a preliminary review of the Company’s equity transactions since inception, the Company believes a portion of its net operating loss carryforwards may be limited due to equity financings which occurred in 2000, 2004, 2007 and 2014. A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance at beginning of year $ 2,054 $ 2,196 $ 1,159 Additions based on tax positions related to current year 372 83 177 Additions (reductions) based on tax positions related to prior years 5 (225 ) 860 Balance at end of year $ 2,431 $ 2,054 $ 2,196 The unrecognized tax benefits, if recognized and in the absence of a full valuation allowance, would impact the income tax provision by $2.0 million and $1.6 million as of December 31, 2015 and 2014, respectively. Given the Company’s valuation allowance, the uncertain tax positions would not impact the effective tax rate. The Company has elected to include interest and penalties as a component of tax expense. During the years ended December 31, 2015, 2014 and 2013, the Company did not recognize accrued interest and penalties related to unrecognized tax benefits. The Company does not anticipate a significant change in the unrecognized tax benefits over the next twelve months. Because the Company has not utilized any of its net operating loss carryforwards, its federal and state income tax returns are subject to tax authority examination from inception.

401(K) Plan

401(K) Plan	12 Months Ended
	Dec. 31, 2015
Compensation And Retirement Disclosure [Abstract]
401(K) Plan	13. 401(K) PLAN The Company sponsors a 401(k) defined contribution plan covering all employees. To date, there have been no employer contributions to the plan.

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Business Combination	14. BUSINESS COMBINATION On June 10, 2014, in accordance with an agreement and plan of merger, the Company acquired ImmuMetrix, Inc. (“IMX”), a privately held development stage company working in new technologies using donor derived cell-free donor DNA (“dd-cfDNA”) technology for the diagnosis, treatment and management of transplant rejection, immune disorders and diseases, including the development of a new, non-invasive test designed to detect the early stages of solid organ transplant rejection. The Company acquired all ImmunMetrix, Inc. assets associated with transplant diagnostics, including related immune repertoire and infectious diseases. An ImmunMetrix, Inc. successor company retained the limited assets not associated with transplant diagnostics. The acquisition was structured as a tax-free reorganization. The Company acquired all of the issued and outstanding capital stock of ImmuMetrix, Inc. for the total estimated purchase price of $17.2 million consisting of $600,000 in cash; 911,364 shares of the Company’s Series G convertible preferred stock with an estimated fair value of $14.2 million, including 23,229 shares of the Company’s Series G convertible preferred stock with an estimated fair value of $369,000 as a result of the Company’s assumption of ImmuMextrix, Inc. outstanding stock options; and an additional payment of 227,845 shares of CareDx Series G convertible preferred stock if a future milestone is achieved. The Agreement provides that the milestone will be achieved if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States no later than six years after the closing date of the acquisition. All shares of Series G Preferred Stock and options to acquire Series G Preferred Stock converted into common stock and options to acquire common stock immediately prior to the closing of the Company’s initial public offering. The additional shares to be paid for the achievement of the milestone will also be issued in common stock. The fair value of this contingent consideration was $2.3 million at the acquisition date and subjected to remeasurement at the end of each reporting period. As of December 31, 2015 and 2014, the contingent consideration fair value was $0.9 million and $1.1 million, respectively. The intellectual property acquired includes an exclusive license from Stanford University to a patent relating to the diagnosis of rejection in organ transplant recipients using dd-cfDNA. The license provides for the Company to pay royalties to Stanford University on sales of the Company’s dd-cfDNA tests. Assets acquired in the business combination consist of In-Process Technology, for which the estimated fair value was $6.7 million at the date of acquisition, and goodwill, for which the estimated fair value was $12.0 million at the date of acquisition. The in-process technology is recorded as an indefinite-life intangible asset until it reaches technological feasibility and will be tested for impairment in accordance with ASC 350, Intangibles-Goodwill and Other. Amortization into earnings will begin once the research and development activities are complete and the technology is proven to work, at which time technological feasibility will have been achieved. The Company expects that will occur at approximately the time when revenue is first generated in the marketplace, currently estimated to be during 2017. Amortization will be based on the estimated remaining useful life of the patent when the product is proven feasible, estimated to be 15 years. Amortization will be recorded using the straight line method. Accordingly, at December 31, 2014 and 2015, accumulated amortization of the in-process technology intangible asset was $0. Given that amortization has not yet begun and technological feasibility has not yet occurred, we cannot currently estimate amortization of the in-process technology asset during each of the next five years. The goodwill recorded from the acquisition of ImmuMetrix, Inc. is primarily related to expected synergies. Substantially all of the goodwill recognized is not deductible for tax purposes. ImmuMetrix, Inc.’s post-acquisition results of operations for the period from June 11, 2014 through December 31, 2014 and for 2015 are included in the Company’s statements of operations. Pro Forma Impact of the Acquisition of IMX The following table presents pro forma results of operations and gives effect to the IMX transaction as if the transaction had been consummated on January 1, 2013. The unaudited pro forma results of operations have been prepared for comparative purposes only and are not necessarily indicative of what would have occurred had the business combination been completed at the beginning of the period or of the results that may occur in the future. Furthermore, the pro forma financial information does not reflect the impact of any reorganization or operating efficiencies resulting from combining the two companies. Year Ended December 31, (in thousands, except per share data). 2014 2013 Net revenue $ 27,306 $ 22,098 Net loss $ (1,080 ) $ (3,768 ) Net loss per common share - basic $ (0.19 ) $ (3.73 ) Net loss per common share - diluted $ (0.19 ) $ (3.73 ) The unaudited pro forma consolidated financial information was prepared using the acquisition method of accounting and is based on the historical financial information of the Company and ImmuMetrix, Inc., reflecting the Company’s and ImmuMextrix, Inc.’s results of operations for the years ended December 31, 2014 and 2013. The historical financial information has been adjusted to give effect to the pro forma events that are: (i) directly attributable to the acquisition, (ii) factually supportable and (iii) expected to have a continuing impact on the combined results. The unaudited pro forma consolidated financial information reflects: (a) the removal of acquisition-related costs of $1.7 million incurred by both CareDx and ImmuMetrix, Inc. for the year ended December 31, 2014 including the removal of $0.2 million of ImmuMetrix, Inc. stock-based compensation expense that resulted from modifications to options in anticipation of the acquisition; (b) the removal of a $1.5 million tax benefit for the year ended December 31, 2014 that resulted from the acquisition; (c) the addition of salaries, benefits and fees for ImmuMetrix, Inc. employees and consultants retained after the acquisition; and (d) the addition of the $1.5 million acquisition-related tax benefit for the year ended December 31, 2013, as if the acquisition had occurred on January 1, 2013 and the benefit had been recognized during the year ended December 31, 2013. Acquisition related expenses are primarily included in general and administrative expenses.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data	15. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) The following table presents selected unaudited consolidated financial data for each of the eight quarters in the two-year period ended December 31, 2015. The Company believes this information reflects all recurring adjustments necessary to fairly present this information when read in conjunction with the Company’s financial statements and the related notes. Net (loss) income per share, basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period. Quarter Ended: March 31 June 30 September 30 December 31 (In thousands, except share and per share data) 2015 Total revenue $ 7,216 $ 7,129 $ 7,151 $ 6,648 Net loss $ (2,272 ) $ (3,185 ) $ (3,489 ) $ (4,761 ) Net loss per common share, basic $ (0.19 ) $ (0.27 ) $ (0.29 ) $ (0.40 ) Net loss per common share, diluted $ (0.19 ) $ (0.27 ) $ (0.29 ) $ (0.40 ) Shares used in calculation of net loss per share, basic 11,814,467 11,835,405 11,890,057 11,902,325 Shares used in calculation of net income loss per share, diluted 11,814,467 11,835,405 11,890,057 11,902,325 2014 Total revenue $ 5,924 $ 6,776 $ 6,654 $ 7,952 Net (loss) income $ (1,304 ) $ 877 $ 1,213 $ (5 ) Net (loss) income per common share, basic $ (1.29 ) $ 0.87 $ 0.13 $ — Net (loss) income per common share, diluted $ (1.29 ) $ 0.13 $ 0.12 $ — Shares used in calculation of net (loss) income per share, basic 1,011,980 1,013,128 9,279,649 11,802,241 Shares used in calculation of net (loss) income per share, diluted 1,011,980 6,939,568 11,219,377 11,802,241

Organization and Description 22

Organization and Description of Business (Policies)	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Reverse Stock Split, and Increase in Authorized Shares	Reverse Stock Split, and Increase in Authorized Shares On July 1, 2014, the Company’s Board of Directors approved an amendment to the Company’s Certificate of Incorporation to reflect a 1 for 6.85 reverse stock split (the “Reverse Stock Split”) of the Company’s outstanding common stock and convertible preferred stock and increase the authorized common stock to 10,000,000 shares, after giving effect to the Reverse Stock Split. The Reverse Stock Split became effective July 14, 2014. The par value per share was not adjusted as a result of the Reverse Stock Split. Effective July 22, 2014, the Company’s certificate of incorporation was amended and restated to provide for 100,000,000 authorized shares of common stock with a par value of $0.001 per share, and 10,000,000 authorized shares of preferred stock with a par value of $0.001 per share. All authorized, issued and outstanding shares of common stock, convertible preferred stock, options and warrants to purchase common or preferred stock and related per share amounts contained in the financial statements have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented.
Initial Public Offering	Initial Public Offering On July 22, 2014, the Company closed its initial public offering (“IPO”) of 4,000,000 shares of its common stock, and issued an additional 220,000 shares of common stock on August 13, 2014 pursuant to the exercise of the over-allotment option granted to its underwriters. The public offering price of the shares sold in the offering was $10.00 per share. The total proceeds from the offering to the Company, net of underwriting discounts and commissions of $3.0 million, were $39.2 million. After deducting offering expenses payable by the Company of $3.7 million, net proceeds to the Company were $35.5 million. Upon the closing of the IPO, all shares of convertible preferred stock then outstanding converted into 6,048,220 shares of common stock, and a subordinated convertible note previously issued by the Company in the principal amount of $5.0 million converted into 510,777 shares of common stock. In addition, all of the Company’s convertible preferred stock warrants were converted into warrants to purchase common stock.
Liquidity and Going Concern	Liquidity and Going Concern The Company has incurred losses and negative cash flows from operations since its inception. As of December 31, 2015, the Company had cash and cash equivalents of approximately $29.9 million, and $15.8 million of debt outstanding under its debt and capital lease obligations, net of debt discount and issuance costs. Even with the Oberland Capital bridge loan, the acquisition will consume a significant portion of the Company’s current cash and cash equivalents. The Company will require additional financing to fund working capital and, within six months following entry into the bridge loan, to refinance the Oberland Capital bridge loan. The Company is pursuing financing opportunities in both the private and public debt and equity markets through sales of equity or debt securities. On August 10, 2015, the Company filed a registration statement on Form S-3 with the Securities and Exchange Commission pursuant to which it is allowed to sell equity and debt securities, subject to limitations on amount. The Company cannot initiate sales under the Form S-3 until mid-2016. Absent additional funding and assuming completion of the acquisition and entry into the bridge loan, the Company will exhaust its cash and cash equivalents in July 2016 unless the Company substantially reduces its costs and operations, including research and development and other operating costs. As a result of the Company’s obligations and lack of current available financial resources, there is uncertainty regarding the Company’s ability to maintain liquidity sufficient to operate its business effectively, which raises substantial doubt about the Company’s ability to continue as a going concern. If the Company is unsuccessful in its efforts to raise outside capital in the near term, the Company will be required to significantly reduce or cease operations. The accompanying financial statements have been prepared assuming that the Company will continue as a going concern for a period of one year December 31, 2015, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern.
Basis of Presentation	Basis of Presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Subsequent to its acquisition in 2014, the financial statements of ImmuMetrix, Inc., which was the Company’s wholly-owned subsidiary and was merged into the Company, were included in the financial statements of the Company.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities and the reported amounts of revenues and expenses in the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to (i) revenue recognition, (ii) the differences between amounts billed and estimated receipts from payers, (iii) the determination of the accruals for clinical studies, (iv) the determination of refunds to be requested by third-party payers, (v) the fair value of assets and liabilities, (vi) the valuation of warrants to purchase convertible preferred stock, (vii) the determination of fair value of the Company’s common stock, (viii) the contingent consideration in a business acquisition, (ix) the fair value of the embedded derivative associated with the subordinated convertible note, (x) the determination of the valuation allowance and estimated tax benefit associated with deferred tax assets and net deferred tax liability, (xi) any impairment of long-lived assets including in-process technology and goodwill and (xii) legal contingencies. Actual results could differ from those estimates.
Concentrations of Credit Risk and Other Risks and Uncertainties	Concentrations of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable. The Company’s policy is to invest its cash and cash equivalents in money market funds, obligations of U.S. government agencies and government-sponsored entities, commercial paper, and various bank deposit accounts. These financial instruments were held in Company accounts at two financial institutions. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. The Company is exposed to credit risk in the event of default by the financial institutions to the extent of amounts recorded on the balance sheets which may be in excess of insured limits. The Company is also subject to credit risk from its accounts receivable which are derived from revenue earned from AlloMap tests provided for patients located in the U.S. and billed to various third-party payers. The Company has not experienced any significant credit losses and does not generally require collateral on receivables. For the years ended December 31, 2015, 2014 and 2013, approximately 50%, 51% and 53%, respectively, of testing revenue was paid for by Medicare. No other payers represented more than 10% of testing revenue for these periods. At December 31, 2015 and 2014, approximately 35% and 78%, respectively, of accounts receivable was due from Medicare. At December 31, 2015, approximately 21% of accounts receivable was due from Aetna. No other payer represented more than 10% of accounts receivable at December 31, 2015 or 2014.
Cash Equivalents	Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds.
Restricted Cash	Restricted Cash Under lease agreements for certain facilities and an agreement with the State of Florida Medicaid, the Company must maintain letters of credit, minimum collateral requirements, and a surety bond. These agreements are collateralized by cash. The cash which will continue long-term to support these arrangements is classified as restricted cash on the accompanying balance sheets.
Inventory	Inventory Inventory is finished goods and raw materials which consist of AlloMap reagent plates, laboratory supplies and reagents. Inventories are used in connection with tests performed and may also be used for research and product development efforts. Laboratory supplies subsequently designated for research and product development use are expensed. Obsolete or damaged inventories are written off and excluded from the physical inventory. Inventories are stated at the lower of actual purchased cost determined on a first-in, first-out basis, or net realizable value.
Property and Equipment, net	Property and Equipment, net Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets, generally three years for laboratory, computer, and office equipment, and generally seven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of their estimated useful lives or the remaining lease term. Assets held under capital leases are recorded at the lower of the net present value of the minimum lease payments or the fair market value of the leased asset at the inception of the lease. Amortization expense is computed using the straight-line method over the shorter of the estimated useful lives of the assets or the period of the related lease. The Company capitalizes certain costs incurred for software developed or obtained for internal use. These costs include software licenses, consulting services, and direct materials, as well as employee payroll and payroll-related costs. Capitalized internal-use software costs are depreciated over three years.
Purchased Intangible Assets	Purchased Intangible Assets Acquired intangible assets with indefinite useful lives are related to purchased in-process research and development, or IPR&D, projects and are measured at their respective fair values as of the acquisition date. The Company does not amortize goodwill and intangible assets with indefinite useful lives. Intangible assets related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated R&D efforts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time. The Company tests IPR&D for impairment on an annual basis and in between annual tests if it becomes aware of any events or changes that would indicate that it is more likely than not that the fair value of the assets is below their carrying amounts. The IPR&D annual impairment test is performed as of December 1 of each fiscal year. If the fair value exceeds the carrying value, then there is no impairment. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of the asset to its carrying value, without consideration of any recoverability test. The Company has not identified any such impairment losses to date.
Impairment of Long-lived Assets	Impairment of Long-lived Assets The Company evaluates its long-lived assets for indicators of possible impairment when events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. The Company then compares the carrying amounts of the assets with the future net undiscounted cash flows expected to be generated by such asset. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value determined using discounted estimates of future cash flows. The Company has not identified any such impairment losses to date.
Goodwill	Goodwill Goodwill represents the excess of the cost of an acquisition over the sum of the amounts assigned to tangible and identifiable intangible assets acquired, less liabilities assumed. Goodwill is not subject to amortization, but is tested for impairment on an annual basis and whenever events or changes in circumstances indicate the carrying amount of these assets may not be recoverable. The Company has determined that it operates in a single segment and has a single reporting unit associated with the development and commercialization of diagnostic products. In the event that the Company determines that it is more likely than not that the carrying value of the reporting unit is higher than its fair value, quantitative testing is performed comparing recorded values to estimated fair values. If impairment is present, it is measured as the excess of recorded goodwill over its implied fair value. The Company performs its annual evaluation of goodwill on December 1 of each fiscal year. There have been no impairments recorded to date.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which the Company would transact, and it takes into consideration the assumptions that market participants would use when pricing the asset or liability. The Company’s assessment of the significance of a particular input to the fair value measurement of an asset or liability requires management to make judgments and to consider specific characteristics of that asset or liability. The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, accounts payable, and accrued liabilities, approximate fair value due to their short maturities. The carrying amounts of the convertible preferred stock warrant liability and contingent consideration liability also represents their fair values.
Warrants	Warrants The Company had freestanding warrants enabling counterparties to purchase shares of its convertible preferred stock as of December 31, 2013, which were converted to warrants to purchase common stock on the Company’s IPO date. Freestanding warrants for convertible preferred stock that were contingently redeemable were classified as liabilities on the balance sheet and recorded at their estimated fair value. These warrants were remeasured at each balance sheet date and any change in estimated fair value was recognized in other (expense) income, net on the statements of operations. Upon the completion of the Company’s IPO in July 2014, preferred stock warrants were converted into warrants to purchase common stock, and, accordingly, the liability was reclassified to equity and became no longer subject to remeasurement. In 2015, the Company issued warrants to purchase shares of its common stock in connection with a debt financing (see Note 9). The Company accounts for these warrants as equity based on the estimated fair value of the warrants on the issuance date. The fair value of the outstanding warrants is estimated using the Black-Scholes Model. The Black-Scholes Model requires inputs such as the expected term of the warrants, expected volatility and risk-free interest rate. Certain of these inputs are subjective and require significant analysis and judgment to develop. For the estimate of the expected term, the Company uses the full remaining contractual term of the warrant.
Testing Revenue	Testing Revenue The Company recognizes revenues for tests delivered when the following criteria are met: (i) persuasive evidence that an arrangement exists; (ii) delivery has occurred or services rendered; (iii) the fee is fixed or determinable; and (iv) collectability is reasonably assured. The first criterion is satisfied when a third-party payer makes a coverage decision or enters into a contractual arrangement with the Company for the test. The second criterion is satisfied when the Company performs the test and delivers the test result to the ordering physician. The third criterion is satisfied if the third-party payer’s coverage decision or reimbursement contract specifies a price for the test. The fourth criterion is satisfied based on management’s judgments regarding the collectability of the fees charged under the arrangement. Such judgments include review of past payment history. AlloMap testing may be considered investigational by some payers and not covered under their reimbursement policies. Others may cover the test, but not pay a set or determinable amount. As a result, in the absence of a reimbursement agreement or sufficient payment history, collectability cannot reasonably be assured so revenue is not recognized at the time the test is delivered. If all criteria set forth above are met, revenue is recognized. When the first, third or fourth criteria are not met but third-party payers make a payment to the Company for tests performed, the Company recognizes revenue on the cash basis in the period in which the payment is received. Revenue is recognized on the accrual basis net of adjustments for differences between amounts billed and the estimated receipts from payers. The amount the Company expects to collect may be lower than the agreed upon amount due to several factors, such as the amount of patient co-payments, the existence of secondary payers and claim denials. Estimated receipts are based upon historical payment practices of payers. Differences between estimated and actual cash receipts are recorded as an adjustment to revenue, which have been immaterial to date. Taxes assessed by governmental authorities on revenue, including sales and value added taxes, are excluded from revenue in the statements of operations.
Collaboration and License Revenue	Collaboration and License Revenue The Company generates revenue from collaboration and license agreements. Collaboration and license agreements may include non-refundable upfront payments, partial or complete reimbursement of research and development costs, contingent payments based on the occurrence of specified events under the agreements, license fees and royalties on sales of products or product candidates if they are successfully commercialized. The Company’s performance obligations under the collaborations may include the transfer of intellectual property rights in the form of licenses, obligations to provide research and development services and obligations to participate on certain development committees with the collaboration partners. The Company makes judgments that affect the periods over which it recognizes revenue. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any change in estimated periods of performance on a prospective basis. The Company recognizes contingent consideration received from the achievement of a substantive milestone in its entirety in the period in which the milestone is achieved, which the Company believes is more consistent with the substance of its performance under its various license and collaboration agreements. The Company did not recognize any milestones during the years ended December 31, 2015, 2014 or 2013.
Cost of Testing	Cost of Testing Cost of testing reflects the aggregate costs incurred in delivering the Company’s AlloMap test results to clinicians. The components of cost of testing are materials and service costs, direct labor costs, including stock-based compensation, equipment and infrastructure expenses associated with testing samples, shipping, logistics and specimen processing charges to collect and transport samples and allocated overhead including rent, information technology, equipment depreciation and utilities and royalties. Costs associated with performing tests (except royalties) are recorded as the test is processed regardless of whether and when revenue is recognized with respect to that test. As a result, the Company’s cost of testing as a percentage of revenue may vary significantly from period to period because the Company does not recognize all revenue in the period in which the associated costs are incurred. Royalties for licensed technology, calculated as a percentage of test revenues, are recorded as license fees in cost of testing at the time the test revenues are recognized.
Business Combinations	Business Combinations The Company determines and allocates the purchase price of an acquired business to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values as of the business combination date, including identifiable intangible assets which either arise from a contractual or legal right or are separable from goodwill. The Company bases the estimated fair value of identifiable intangible assets acquired in a business combination on independent valuations that use information and assumptions provided by management, which consider management’s best estimates of inputs and assumptions that a market participant would use. The Company allocates any excess purchase price over the estimated fair value assigned to the net tangible and identifiable intangible assets acquired and liabilities assumed to goodwill. The use of alternative valuation assumptions, including estimated revenue projections, growth rates, royalty rates, cash flows, discount rates, estimated useful lives and probabilities surrounding the achievement of contingent milestones could result in different purchase price allocations and amortization expense in current and future periods. In those circumstances where an acquisition involves a contingent consideration arrangement that meets the definition of a liability under ASC 480, Distinguishing Liabilities from Equity, the Company recognizes a liability equal to the fair value of the contingent payments the Company expects to make as of the acquisition date. The Company remeasures this liability each reporting period and records changes in the fair value as a component of operating expenses. Transaction costs associated with these acquisitions are expensed as incurred in general and administrative expenses. Results of operations and cash flows of acquired companies are included in the Company’s operating results from the date of acquisition.
Research and Development Expenses	Research and Development Expenses Research and development expenses represent costs incurred to develop new surveillance solutions as well as continued development of the Company’s AlloMap test. These expenses include payroll and related expenses, consulting expenses, laboratory supplies, and certain allocated expenses as well as amounts incurred under certain collaboration and license agreements. Research and development costs are expensed as incurred. The Company records accruals for estimated study costs comprised of work performed by contract research organizations under contract terms.
Advertising Expenses	Advertising Expenses All advertising costs are expensed as incurred. Advertising expenses were insignificant during all of the periods presented.
Stock-based Compensation	Stock-based Compensation The Company uses the Black-Scholes valuation model, which requires the use of estimates such as stock price volatility and expected option lives, to value employee stock options. The Company estimates the expected option lives using historical data, volatility using data of similar companies in the diagnostics industry, and risk-free rates based on the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected option lives, and dividend yield based on the Company’s historical data. The Company uses the straight-line attribution method for recognizing compensation expense. Compensation expense is recognized on awards ultimately expected to vest and reduced for forfeitures that are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures are estimated based on the Company’s historical experience. Compensation expense for stock options issued to nonemployees is calculated using the Black-Scholes option pricing model and is recorded over the service performance period. Options subject to vesting are required to be periodically remeasured over their service performance period, which is generally the same as the vesting period.
Income Taxes	Income Taxes The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. The Company’s assessment of an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit may change as new information becomes available.
Comprehensive (Loss) Income	Comprehensive (Loss) Income Net (loss) income and comprehensive (loss) income are the same for all periods presented.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Presentation of Financial Statements―Going Concern (Subtopic 205-40), Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern alleviate that doubt. This guidance is effective for annual periods beginning after December 15, 2016, and interim periods within those fiscal years. Early adoption is permitted but the Company has not elected to early adopt this guidance. In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued ASU 2015-05, Intangibles—Goodwill and Other—Internal Use Software (Subtopic 350-40) In November 2015, the FASB issued ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes, In February 2016, the FASB issued ASU 2016-02, Leases,

Net (Loss) Income Per Share (Ta

Net (Loss) Income Per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net (Loss) Income Per Share	The following tables set forth the computation of the Company’s basic and diluted net (loss) income per share (in thousands, except shares and per share data): Year Ended December 31, 2015 2014 2013 Numerator: Net (loss) income $ (13,707 ) $ 781 $ (3,542 ) Add: interest expense related to subordinated convertible note — 364 — Less: gain on change in fair value of derivative related to subordinated convertible note — (118 ) — Less: gain on extinguishment of derivative related to subordinated convertible note — (120 ) — Net (loss) income attributable to common stockholders $ (13,707 ) $ 907 $ (3,542 ) Denominator: Weighted-average shares used to compute basic net (loss) income per share attributable to common stockholders 11,860,885 5,815,928 1,010,795 Effect of potentially dilutive securities: Convertible preferred stock — 2,972,051 — Subordinated convertible note — 134,341 — Employee stock options — 360,681 — Weighted-average shares used to compute diluted net (loss) income per share attributable to common stockholders 11,860,885 9,283,001 1,010,795 Net (loss) income per share attributable to common stockholders: Basic $ (1.16 ) $ 0.13 $ (3.50 ) Diluted $ (1.16 ) $ 0.10 $ (3.50 )
Potentially Dilutive Securities Excluded from Diluted Net (Loss) Income Per Share	The following potentially dilutive securities have been excluded from diluted net (loss) income per share, because their effect would be antidilutive: Year Ended December 31, 2015 2014 2013 Shares of common stock subject to outstanding options 1,577,317 539,645 466,965 Shares of common stock subject to outstanding common stock warrants 301,069 213,677 82,190 Shares of common stock subject to conversion from preferred stock — — 5,160,085 Shares of common stock subject to conversion from preferred stock warrants — — 541,613 Restricted stock units 106,200 — — Total common stock equivalents 1,984,586 753,322 6,250,853

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table sets forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis, as of December 31, 2015 and 2014 (in thousands): December 31, 2015 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 28,774 $ — $ — $ 28,774 Liabilities Contingent consideration $ — $ — $ 948 $ 948 December 31, 2014 Fair Value Measured Using (Level 1) (Level 2) (Level 3) Total Balance Assets Money market funds $ 36,779 $ — $ — $ 36,779 Liabilities Contingent consideration $ — $ — $ 1,074 $ 1,074
Summary of Issuances, Changes in Fair Value and Reclassifications of Level 3 Financial Instruments	The following table presents the issuances, changes in fair value and reclassifications of the Company’s Level 3 financial instruments that are measured at fair value on a recurring basis (in thousands): (Level 3) Contingent Consideration Liability Warrants to Purchase Convertible Preferred Stock Derivative Liability Related to Subordinated Convertible Note Total Balance as of December 31, 2013 $ — $ 525 $ — $ 525 Issuance of financial instruments 2,313 — 239 2,552 Change in estimated fair value (1,239 ) 14 (239 ) (1,464 ) Reclassification to stockholders' equity — (539 ) (539 ) Balance as of December 31, 2014 1,074 — — 1,074 Change in estimated fair value (126 ) (126 ) Balance as of December 31, 2015 $ 948 $ — $ — $ 948

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Inventory	Inventory consisted of the following (in thousands): December 31, 2015 2014 Finished goods $ 237 $ 277 Raw materials 529 409 Total inventory $ 766 $ 686
Components of Property and Equipment	Property and equipment consisted of the following (in thousands): December 31, 2015 2014 Laboratory equipment $ 5,022 $ 4,392 Leasehold improvements 4,326 4,040 Furniture and fixtures 825 825 Computer and office equipment 4,125 3,775 Construction-in-process — 28 14,298 13,060 Less: Accumulated depreciation and amortization (11,873 ) (11,092 ) Property and equipment, net $ 2,425 $ 1,968
Components of Accrued and Other Liabilities	Accrued and other liabilities consisted of the following (in thousands): December 31, 2015 2014 Professional fees $ 880 $ 273 Test sample processing fees 426 318 Accrued overpayments and refunds 163 146 Clinical studies 756 144 Deferred rent – current portion 258 202 Capital leases – current portion 71 70 Other accrued expenses 338 463 Total accrued and other liabilities $ 2,892 $ 1,616

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Lease Commitments under Operating and Capital Leases	Future minimum lease commitments under these operating and capital leases at December 31, 2015, are as follows (in thousands): Years ending December 31, Capital Leases Operating leases 2016 $ 75 $ 1,291 2017 55 1,348 2018 16 1,376 2019 5 1,404 2020 and thereafter — 1,432 Total minimum lease payments 151 $ 6,851 Less: amounts representing interest (23 ) Present value of minimum lease payments 128 Less: current portion of obligations under capital leases (71 ) Long-term portion of obligations under capital leases $ 57

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Transfers And Servicing [Abstract]
Summary of Aggregate Annual Payments Net of Interest Due	Aggregate annual payments, net of interest, at December 31, 2015 due on the Loan Agreement are as follows (in thousands): Year ending December 31: Annual Payments 2016 $ 3,021 2017 6,309 2018 6,670 16,000 Less: debt discount and issuance costs (304 ) 15,696 Less: current portion, net of debt discount and issuance costs (2,866 ) Long-term portion, net of debt discount and issuance costs $ 12,830

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2015
Common Stock [Member]
Class Of Warrant Or Right [Line Items]
Components of Warrants Outstanding	At December 31, 2015, outstanding common stock warrants consisted of: Original Term Exercise Price Number of Shares Underlying Warrants Original issue date: July 2006 10 years $ 31.72 17,656 November 2006 10 years $ 31.72 1,576 February 2008 10 years $ 35.07 22,792 August 2009 10 years $ 21.78 33,472 July 2010 9 years $ 21.78 6,694 January 2015 5 years $ 6.96 34,483 116,673

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Option Activity and Related Information	The following table summarizes option activity under the plans, and related information: Shares Available for Grant Stock Options Outstanding Weighted- average Exercise Price Balance—December 31, 2012 180,266 619,906 $ 2.67 Granted (4,081 ) 4,081 0.48 Exercised — (212 ) 0.55 Forfeited 7,247 (7,247 ) 2.33 Expired 149,563 (149,563 ) 4.73 Balance—December 31, 2013 332,995 466,965 1.99 Additional options authorized 940,884 — — Granted (585,345 ) 585,345 11.76 Assumed in business combination — 23,229 2.06 Exercised — (9,363 ) 2.14 Forfeited 20,591 (20,591 ) 10.36 Expired 13,781 (13,781 ) 2.74 Balance—December 31, 2014 722,906 1,031,804 7.36 Additional options authorized 357,075 — — Granted (652,078 ) 652,078 6.09 Exercised — (23,576 ) 1.94 Forfeited 77,660 (77,660 ) 8.13 Expired 5,329 (5,329 ) 10.36 Balance—December 31, 2015 510,892 1,577,317 6.87
Schedule of Outstanding, Exercisable and Vested Stock Options	Outstanding, exercisable and vested stock options as of December 31, 2015 are summarized as follows: Option s Options Vested at December 31, 2015 Range of Exercise Prices Number of Options Outstanding Weighted Average Remaining Contractual Life (Years) Weighted Average Exercise Price Number of Options Weighted Average Exercise Price $0.27 - 0.56 193,581 6.80 $ 0.55 166,699 $ 0.55 $2.05 - 3.06 135,656 5.88 2.83 135,656 2.83 $3.36 - 6.98 716,157 8.28 5.68 127,859 3.84 $7.03 - 12.44 531,923 8.38 11.80 249,779 11.79 1,577,317 7.92 6.87 679,993 5.75
Summary of Options Outstanding and Exercisable Vested or Expected to Vest	Options outstanding that have vested and are expected to vest at December 31, 2015 are as follows: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual (Years) Aggregate Intrinsic Value (In Vested 679,993 $ 5.75 6.58 $ 1,788 Expected to Vest 897,324 7.71 8.95 $ 435 Total 1,577,317 6.87 7.92 $ 2,223
Weighted-Average Assumptions Used to Fair Value of Share-Based Awards	The fair value of employee stock options and ESPP was estimated using the Black-Scholes option-pricing model using the following weighted-average assumptions. Year Ended December 31, 2015 2014 2013 Employee Stock Options Expected term (in years) 6.0 5.1 6.0 Expected volatility 41.17 % 42.18 % 45.25 % Risk-free interest rate 1.84 % 1.69 % 1.21 % Expected dividend yield — % — % — % Employee Stock Purchase Plan Expected term (in years) 0.5 — — Expected volatility 39.10 – — — Risk-free interest rate 0.11 % — — Expected dividend yield — % — % — %
Summary of Unvested RSU Activity	Unvested RSU activity for the year ended December 31, 2015 is summarized below: Number of Shares Weighted- Average Grant Date Fair Value Unvested balance at December 31, 2014 — $ — Granted 114,400 6.49 Vested — — Forfeited (8,200 ) 6.49 Unvested balance at December 31, 2015 106,200 6.49
Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs	The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs, and ESPP for the years ended December 31, 2015, 2014 and 2013, included in the statements of operations as follows (in thousands): Year Ended December 31, 2015 2014 2013 Cost of testing $ 109 $ 28 $ 3 Research and development 247 88 7 Sales and marketing 173 29 3 General and administrative 812 390 59 $ 1,341 $ 535 $ 72

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Difference between Benefit for Income Taxes and Income Taxes at Statutory U.S. Federal Income Tax Rate	A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows: Year Ended December, 31, 2015 2014 2013 Federal tax at statutory rate 34.0 % 34.0 % 34.0 % Stock-based compensation -1.9 % -9.5 % -11.4 % Change in valuation allowance -31.1 % 190.6 % -8.6 % Change in unrecognized tax benefits 0.0 % 0.0 % -8.4 % Preferred stock warrant revaluation 0.0 % -0.7 % -5.0 % Interest expense 0.0 % -5.8 % 0.0 % Contingent liability for IMX acquisition 0.0 % 38.2 % 0.0 % Acquisition costs -3.2 % -36.7 % 0.0 % Other 2.2 % -1.3 % -0.6 % Effective income tax rate 0.0 % 208.8 % 0.0 %
Schedule of Tax Effects of Temporary Differences and Carryforwards that Rise to Significant Deferred Tax Assets and Liabilities	The tax effects of temporary differences and carryforwards that give rise to significant deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 65,957 $ 63,116 Tax credit carryforwards 4,533 4,065 Accruals 1,125 942 Other 698 551 Gross deferred tax assets 72,313 68,674 Deferred tax liabilities: Property and equipment 95 (8 ) Purchased intangibles (2,355 ) (2,349 ) Total deferred tax liabilities (2,260 ) (2,357 ) Valuation allowance (70,053 ) (66,317 ) Net deferred tax assets $ — $ —
Schedule of Reconciliation of Unrecognized Tax Benefits	A reconciliation of the Company’s unrecognized tax benefits is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Balance at beginning of year $ 2,054 $ 2,196 $ 1,159 Additions based on tax positions related to current year 372 83 177 Additions (reductions) based on tax positions related to prior years 5 (225 ) 860 Balance at end of year $ 2,431 $ 2,054 $ 2,196

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of Pro Forma Results of Operations	The following table presents pro forma results of operations and gives effect to the IMX transaction as if the transaction had been consummated on January 1, 2013. The unaudited pro forma results of operations have been prepared for comparative purposes only and are not necessarily indicative of what would have occurred had the business combination been completed at the beginning of the period or of the results that may occur in the future. Furthermore, the pro forma financial information does not reflect the impact of any reorganization or operating efficiencies resulting from combining the two companies. Year Ended December 31, (in thousands, except per share data). 2014 2013 Net revenue $ 27,306 $ 22,098 Net loss $ (1,080 ) $ (3,768 ) Net loss per common share - basic $ (0.19 ) $ (3.73 ) Net loss per common share - diluted $ (0.19 ) $ (3.73 )

Selected Quarterly Financial 32

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summary of Selected Quarterly Financial Data	The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period. Quarter Ended: March 31 June 30 September 30 December 31 (In thousands, except share and per share data) 2015 Total revenue $ 7,216 $ 7,129 $ 7,151 $ 6,648 Net loss $ (2,272 ) $ (3,185 ) $ (3,489 ) $ (4,761 ) Net loss per common share, basic $ (0.19 ) $ (0.27 ) $ (0.29 ) $ (0.40 ) Net loss per common share, diluted $ (0.19 ) $ (0.27 ) $ (0.29 ) $ (0.40 ) Shares used in calculation of net loss per share, basic 11,814,467 11,835,405 11,890,057 11,902,325 Shares used in calculation of net income loss per share, diluted 11,814,467 11,835,405 11,890,057 11,902,325 2014 Total revenue $ 5,924 $ 6,776 $ 6,654 $ 7,952 Net (loss) income $ (1,304 ) $ 877 $ 1,213 $ (5 ) Net (loss) income per common share, basic $ (1.29 ) $ 0.87 $ 0.13 $ — Net (loss) income per common share, diluted $ (1.29 ) $ 0.13 $ 0.12 $ — Shares used in calculation of net (loss) income per share, basic 1,011,980 1,013,128 9,279,649 11,802,241 Shares used in calculation of net (loss) income per share, diluted 1,011,980 6,939,568 11,219,377 11,802,241

Organization and Description 33

Organization and Description of Business - Additional Information (Detail) $ / shares in Units, $ in Thousands		Dec. 16, 2015USD ($)	Aug. 13, 2014shares	Jul. 22, 2014USD ($)$ / sharesshares	Dec. 31, 2015USD ($)Segment$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)	Jul. 01, 2014shares	Dec. 31, 2012USD ($)
Schedule of Capitalization, Equity [Line Items]
Number of operating segment | Segment					1
Reverse stock split					1 for 6.85
Reverse stock split, ratio					0.145985401
Reverse Stock Split effective date					Jul. 14, 2014
Common stock, shares authorized | shares				100,000,000	100,000,000	100,000,000		10,000,000
Common stock, par value | $ / shares				$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized | shares				10,000,000	10,000,000	10,000,000
Preferred stock, par value | $ / shares				$ 0.001	$ 0.001	$ 0.001
Underwriting discounts and commissions					$ 0	$ 3,733	$ 0
Proceeds from initial public offering net of underwriting discounts and commissions					0	39,246	0
Shares issued upon conversion | shares				510,777
Cash and cash equivalents					29,888	$ 36,431	$ 5,128		$ 5,830
Debt outstanding under debt and capital lease obligations					$ 15,800
Loan interest rate, per annum					9.95%
Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Percentage of share acquired		78.00%
Total purchase price combination of cash and common stock	[1]	$ 35,000
Business Combination Debt Refinancing		$ 16,000
Borrowed loan, maturity period		6 months
Bridge Loan		$ 18,000			$ 18,000
Prepayment premium percentage on prepayments of loan for first month		5.00%
Decrease in interest rate for prepayment premium after first month		1.00%
Bridge Loan [Member] | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Borrowed loan, maturity period					6 months
Fees incurred		$ 1,000
Loan interest rate, per annum	[2]				20.00%
Prepayment premium percentage on prepayments of loan for first month					5.00%
Decrease in interest rate for prepayment premium after first month					1.00%
Cash Alternative [Member] | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Cash distribution to acquire business, gross		27,000
Mixed Consideration Alternative [Member] | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Cash distribution to acquire business, gross	[3]	$ 24,600
Minimum | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Business acquisition, estimate percentage		90.00%
Maximum | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Business acquisition, estimate percentage		100.00%
Oberland Capital [Member] | Bridge Loan [Member] | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Fees incurred					$ 1,600
Third Parties In Connection With the Bridge Loan [Member] | Bridge Loan [Member] | Allenex [Member]
Schedule of Capitalization, Equity [Line Items]
Fees incurred		$ 0			$ 400
Convertible Subordinated Debt [Member]
Schedule of Capitalization, Equity [Line Items]
Shares issued upon conversion | shares				510,777
Convertible note principal amount				$ 5,000
Common Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Common stock shares issued from IPO | shares						510,777
Shares issued upon conversion | shares				6,048,220
IPO [Member]
Schedule of Capitalization, Equity [Line Items]
Common stock shares issued from IPO | shares				4,000,000
Public offering price per share | $ / shares				$ 10
Underwriting discounts and commissions				$ 3,000
Proceeds from initial public offering net of underwriting discounts and commissions				39,200
Offering expenses				3,700
Net proceeds from issuance of initial public offering				$ 35,500
Over Allotment Option
Schedule of Capitalization, Equity [Line Items]
Common stock shares issued from IPO | shares			220,000
[1]	35
[2]	20
[3]	24.6

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Information - Concentration of Credit Risk (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Services Revenue [Member] | Customer Concentration Risk [Member] | Minimum
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%	10.00%
Services Revenue [Member] | Customer Concentration Risk [Member] | Medicare [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	50.00%	51.00%	53.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Minimum
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Medicare [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	35.00%	78.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Aetna [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	21.00%

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents maturity, description	Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase.
Impairment of Long-lived Assets	$ 0
Impairment of goodwill	0	$ 0
Revenue recognition under milestone method	0	0	$ 0
Debt discount and issuance liability component, current	155,000	76,000
Debt discount and issuance liability component, non-current	$ 149,000	$ 11,000
Laboratory, Computer, and Office Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years
Furniture and Fixtures [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	7 years
Capitalized Internal-use Software Costs [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years

Proposed Business Combination -

Proposed Business Combination - Additional Information (Detail) $ / shares in Units, $ in Millions		Dec. 16, 2015USD ($)Unitholder	Dec. 31, 2015USD ($)$ / shares	Mar. 07, 2016
Business Acquisition [Line Items]
Loan interest rate, per annum			9.95%
Allenex [Member]
Business Acquisition [Line Items]
Percentage of share acquired		78.00%
Number of principal shareholders | Unitholder		3
Total purchase price combination of cash and common stock	[1]	$ 35
Business Combination Debt Refinancing		16
Bridge Loan		$ 18	$ 18
Borrowed loan, maturity period		6 months
Prepayment premium percentage on prepayments of loan for first month		5.00%
Decrease in interest rate for prepayment premium after first month		1.00%
Allenex [Member] | Bridge Loan [Member]
Business Acquisition [Line Items]
Borrowed loan, maturity period			6 months
Fees incurred		$ 1
Loan interest rate, per annum	[2]		20.00%
Prepayment premium percentage on prepayments of loan for first month			5.00%
Decrease in interest rate for prepayment premium after first month			1.00%
Allenex [Member] | Third Parties In Connection With the Bridge Loan [Member] | Bridge Loan [Member]
Business Acquisition [Line Items]
Fees incurred		0	$ 0.4
Allenex [Member] | Cash Alternative [Member]
Business Acquisition [Line Items]
Business acquisition, share price | $ / shares			$ 0.30
Cash distribution to acquire business, gross		27
Allenex [Member] | Mixed Consideration Alternative [Member]
Business Acquisition [Line Items]
Business acquisition, share price | $ / shares			0.20
Cash distribution to acquire business, gross	[3]	$ 24.6
Allenex [Member] | Common Stock [Member] | Mixed Consideration Alternative [Member]
Business Acquisition [Line Items]
Business acquisition, share price | $ / shares			$ 0.01458
Subsequent Event | Allenex [Member]
Business Acquisition [Line Items]
Percentage of outstanding share for tender				22.00%
Minimum | Allenex [Member]
Business Acquisition [Line Items]
Business acquisition, estimate percentage		90.00%
Maximum | Allenex [Member]
Business Acquisition [Line Items]
Business acquisition, estimate percentage		100.00%
[1]	35
[2]	20
[3]	24.6

Net (Loss) Income Per Share - C

Net (Loss) Income Per Share - Computation of Basic and Diluted Net (Loss) Income Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net (loss) income	$ (4,761)	$ (3,489)	$ (3,185)	$ (2,272)	$ (5)	$ 1,213	$ 877	$ (1,304)	$ (13,707)	$ 781	$ (3,542)
Add: interest expense related to subordinated convertible note									0	364	0
Less: gain on change in fair value of derivative related to subordinated convertible note									0	(118)	0
Less: gain on extinguishment of derivative related to subordinated convertible note									0	(120)	0
Net (loss) income attributable to common stockholders									$ (13,707)	$ 907	$ (3,542)
Denominator:
Weighted-average shares used to compute basic net (loss) income per share attributable to common stockholders	11,902,325	11,890,057	11,835,405	11,814,467	11,802,241	9,279,649	1,013,128	1,011,980	11,860,885	5,815,928	1,010,795
Effect of potentially dilutive securities:
Convertible preferred stock									0	2,972,051	0
Subordinated convertible note									0	134,341	0
Employee stock options									0	360,681	0
Weighted-average shares used to compute diluted net (loss) income per share attributable to common stockholders	11,902,325	11,890,057	11,835,405	11,814,467	11,802,241	11,219,377	6,939,568	1,011,980	11,860,885	9,283,001	1,010,795
Basic	$ (0.40)	$ (0.29)	$ (0.27)	$ (0.19)	$ 0	$ 0.13	$ 0.87	$ (1.29)	$ (1.16)	$ 0.13	$ (3.50)
Diluted	$ (0.40)	$ (0.29)	$ (0.27)	$ (0.19)	$ 0	$ 0.12	$ 0.13	$ (1.29)	$ (1.16)	$ 0.10	$ (3.50)

Net (Loss) Income Per Share - P

Net (Loss) Income Per Share - Potentially Dilutive Securities Excluded from Diluted Net (Loss) Income Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	1,984,586	753,322	6,250,853
Shares of common stock subject to outstanding options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	1,577,317	539,645	466,965
Shares of common stock subject to outstanding common stock warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	301,069	213,677	82,190
Shares of common stock subject to conversion from preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	0	0	5,160,085
Shares of common stock subject to conversion from preferred stock warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	0	0	541,613
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net income (loss) per share attributable to common stockholders, Total	106,200	0	0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Money market funds	$ 28,774	$ 36,779
Liabilities
Contingent consideration	948	1,074
Fair Value Measured Using - (Level 1) [Member]
Assets
Money market funds	28,774	36,779
Liabilities
Contingent consideration	0	0
Fair Value Measured Using - (Level 2) [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration	0	0
Fair Value Measured Using - (Level 3) [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration	$ 948	$ 1,074

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Issuances, Changes in Fair Value and Reclassifications of Level 3 Financial Instruments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	$ 1,074	$ 525
Issuance of financial instruments		2,552
Change in estimated fair value	(126)	(1,464)
Reclassification to stockholders' equity		(539)
Ending Balance	948	1,074
Significant Unobservable Inputs (Level 3), Warrants to Purchase Convertible Preferred Stock [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	0	525
Issuance of financial instruments		0
Change in estimated fair value	0	14
Reclassification to stockholders' equity		(539)
Ending Balance	0	0
Significant Unobservable Inputs (Level 3), Derivative Liability Related to Subordinated Convertible Note [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	0	0
Issuance of financial instruments		239
Change in estimated fair value	0	(239)
Reclassification to stockholders' equity		0
Ending Balance	0	0
Significant Unobservable Inputs (Level 3), Contingent Consideration Liability [Member]
Significant Unobservable Inputs (Level 3) [Line Items]
Beginning Balance	1,074	0
Issuance of financial instruments		2,313
Change in estimated fair value	(126)	(1,239)
Reclassification to stockholders' equity		0
Ending Balance	$ 948	$ 1,074

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	Apr. 17, 2014USD ($)	Jul. 31, 2014USD ($)	Dec. 31, 2015USD ($)CommercialTestshares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers between Level 1, Level 2 and Level 3 categories during the periods			$ 0
Illumina, Inc. [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Subordinated convertible promissory note issued	$ 5,000,000
Change in control for repayment	10.00%
Estimated fair value of embedded derivative liabilities	$ 239,000
Illumina, Inc. [Member] | IPO [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of embedded derivative liabilities		$ 0
Gain on derivative		$ 239,000
ImmuMetrix, Inc. [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Milestone description			the milestone will be achieved if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States no later than six years after the closing date of the acquisition.
ImmuMetrix, Inc. [Member] | Contingent consideration [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent obligation to issue common stock | shares			227,845
Number of commercial tests involving the measurement of cfDNA to be completed | CommercialTest			2,500
Milestone description			The issuance will occur if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020.
Probability of the achievement			65.00%

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods	$ 237	$ 277
Raw materials	529	409
Total inventory	$ 766	$ 686

Balance Sheet Components - Comp

Balance Sheet Components - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 14,298	$ 13,060
Less: Accumulated depreciation and amortization	(11,873)	(11,092)
Property and equipment, net	2,425	1,968
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	5,022	4,392
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	4,326	4,040
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	825	825
Computer and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	4,125	3,775
Construction-in-process [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 0	$ 28

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Balance Sheet Components [Line Items]
Depreciation and amortization expense	$ 796,000	$ 512,000	$ 663,000
Accumulated amortization	11,873,000	11,092,000
Amortization expense, included in depreciation and amortization expense	79,000	59,000	$ 26,000
Laboratory, Computer, and Office Equipment [Member]
Balance Sheet Components [Line Items]
Assets purchased under capital leases	1,700,000	1,600,000
Accumulated amortization	$ 1,500,000	$ 1,500,000

Balance Sheet Components - Co45

Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Professional fees	$ 880	$ 273
Test sample processing fees	426	318
Accrued overpayments and refunds	163	146
Clinical studies	756	144
Deferred rent - current portion	258	202
Capital leases - current portion	71	70
Other accrued expenses	338	463
Total accrued and other liabilities	$ 2,892	$ 1,616

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Loss Contingencies [Line Items]
Operating lease agreement expiry date		2020-12
Rent expense under non-cancelable operating leases		$ 1,000,000	$ 1,000,000	$ 1,000,000
Royalty revenues		$ 179,000	221,000	94,000
Unpaid Royalties [Member]
Loss Contingencies [Line Items]
Settlement and mutual release agreement, counter party name		Roche
Settlement and mutual release agreement, date		September 2,014
Past due royalties						$ 2,827,220
Maximum number of days from end of calendar quarter for royalty payment		45 days
Settlement and mutual release agreement, terms of agreement		In September 2014, the Company entered into a settlement and mutual release agreement with Roche whereby: (i) for the period beginning July 1, 2011 through June 30, 2014, the Company agreed to pay the amount of $2,827,220 in settlement of past royalties due; (ii) for the period beginning July 1, 2014 through September 30, 2014, the Company agreed to pay royalties based on the same combination services percentage used to determine the past royalties due; (iii) for the period beginning October 1, 2014 through September 30, 2017, Roche and the Company agreed to a downward adjustment of the combination services percentage used to determine the portion of the AlloMap testing revenue that is royalty bearing under the terms of the license; (iv) the Company agreed to report and pay quarterly royalties within 45 days of the end of each calendar quarter; (v) Roche agreed that, subject to the Company’s timely payment of all applicable royalties through such date, no further royalties will be payable by the Company for periods after September 30, 2017.
Royalty expenses		$ 1,000,000	700,000	1,200,000
Allo Map
Loss Contingencies [Line Items]
Settlement and payment		2,800,000
Decrease in cost of testing		600,000
Decrease in interest expense		$ 100,000
Royalty revenues	$ 400,000		$ 600,000	$ 1,000,000	$ 900,000

Commitments and Contingencies47

Commitments and Contingencies - Future Minimum Lease Commitments under Operating and Capital Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Capital Leases, 2016	$ 75
Capital Leases, 2017	55
Capital Leases, 2018	16
Capital Leases, 2019	5
Capital Leases, 2020 and thereafter	0
Total minimum lease payments under capital leases	151
Less: amounts representing interest of capital leases	(23)
Capital Leases, Present value of minimum lease payments	128
Less: current portion of obligations under capital leases	(71)	$ (70)
Long-term portion of obligations under capital leases	57
Operating leases, 2016	1,291
Operating leases, 2017	1,348
Operating leases, 2018	1,376
Operating leases, 2019	1,404
Operating leases, 2020 and thereafter	1,432
Total minimum lease payments under operating leases	$ 6,851

Collaboration and Licensing A48

Collaboration and Licensing Agreements - Additional Information (Detail)	Sep. 18, 2014USD ($)	Jul. 31, 2013USD ($)	Jun. 30, 2013USD ($)	Jun. 30, 2013EUR (€)	Apr. 30, 2012USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Jun. 30, 2013EUR (€)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Description of agreement expire term														The agreement will expire at the later of the last-to-expire patent in the EEA or ten years from the first commercial sale of the test in the EEA, which occurred in 2014.
Upfront license fee payment																	$ 1,000,000
Non-refundable and non creditable payment received																	$ 250,000
Research and development expenses														$ 9,333,000	$ 3,846,000	$ 3,176,000
Termination agreement fee															500,000	0
Deferred revenue						$ 142,000				$ 505,000				142,000	505,000
Revenue recognized under collaboration and licensing agreements															1,100,000	328,000
Amortization of upfront license fee															626,000	187,000
Reimbursement of research and development expenses															16,000	141,000
Revenues						6,648,000	$ 7,151,000	$ 7,129,000	$ 7,216,000	7,952,000	$ 6,654,000	$ 6,776,000	$ 5,924,000	28,144,000	27,306,000	22,098,000
Common stock value						12,000				12,000				12,000	12,000
Refundable upfront payments			$ 344,000	€ 250,000
Upfront cash payment			503,000	€ 387,500
Shares sold for consideration		$ 467,000
Revenues recognized from the arrangement														46,000	36,000
Royalty revenues														179,000	221,000	94,000
Royalty revenues receivable balance						$ 0				54,000				$ 0	54,000
Up-front Payment Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue										611,000					611,000
Laboratory Corp of America Holdings [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Consideration of arrangement of license					$ 1,000,000
Description of agreement expire term														The license term in the 2012 Agreement was the later of 10 years from the date of the agreement or the expiration of the last-to-expire patents and patent applications included in the CareDx technology licensed to LabCorp, unless the license were terminated by mutual agreement.
Termination of collaboration agreement date														Sep. 18, 2014
Research and development expenses	$ 500,000													$ 0	$ 32,000	$ 282,000
Termination agreement fee										$ 500,000
Revenues														$ 0
Diaxonhit (DHT) [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Common stock value			$ 503,000															€ 387,500

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)	Jan. 30, 2015	Jul. 22, 2014	Aug. 31, 2012	Jul. 22, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 17, 2014	Aug. 31, 2013
Debt Instrument [Line Items]
Loan and security agreement cost			$ 15,000,000
Total repayment of principal			10,333,833
Termination fee paid			875,000
Interest expense								$ 628,000
Net cash proceeds from loan			$ 3,432,260
Loan deferral additional fee					$ 150,000
Principal pay-down of loan begins date					Mar. 1, 2014
Interest payment					$ 566,822
Loan interest rate, per annum					9.95%
Final payment due at the end of the term					$ 1,275,000
Non-refundable commitment fee					$ 75,000
Deferred principal amortization description					Interest-only payments for 18 months followed by 30 equal monthly principal and interest payments
Estimated fair value of warrants					$ 0	$ (225,000)	$ 525,000
Initial Public offering, closing date					Jul. 22, 2014
Shares issued upon conversion		510,777
Amortization of debt discount				$ 256,000
Extinguishment of embedded derivative					$ 120,000
Aggregate principal amount	$ 20,000,000
Interest rate, description					Draw A bears interest at a daily floating rate equal to 2.00%, plus the greater of (i) 3.25% or (ii) the prime rate published by the lender
Interest rate basis spread	2.00%
Loan agreement initiation date					Jan. 30, 2015
Maturity date of term loan facility					Dec. 1, 2018
Debt discount and issuance liability component, current					$ 155,000	76,000
Debt discount and issuance liability component, non-current					$ 149,000	$ 11,000
Prepayment penalty on loan					0.00%
Loan agreement description					The Company agreed to issue to the lender detachable warrants to purchase shares of the Company’s common stock upon the drawdown of each advance in an amount equal to 1.5% of the amount drawn, divided by the exercise price per share for that tranche.
Estimated fair value of warrants	$ 90,000
Default interest rate description					Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and the lender may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Loan Agreement.
Default interest rate percentage					5.00%
Common Stock [Member]
Debt Instrument [Line Items]
Warrant to purchase stock, shares	34,483
Warrant to purchase of stock, per share	$ 6.96
Shares issued upon conversion		6,048,220
Warrants To Purchase Common Stock [Member]
Debt Instrument [Line Items]
Expected volatility rate	39.83%
Contractual term of years	5 years
Risk-free interest rate	1.18%
Underlying common stock price	$ 7.06
Dividend yield	0.00%
Interest Expense [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt					$ 600,000
Draw A [Member]
Debt Instrument [Line Items]
Non-refundable commitment fee	$ 160,000
Loan agreement, amount borrowed	16,000,000
Pay-off of term debt	11,300,000
Secured Term Loan Facility
Debt Instrument [Line Items]
Principal pay-down of loan begins date					Jan. 1, 2016
Deferred principal amortization description					Principal pay-down of the loan begins on January 1, 2016 with the loan being payable in 36 equal installments. The principal pay-down of the loan may be delayed to July 1, 2016 with the loan being payable in 30 equal monthly installments, if on December 31, 2015, the Company has achieved certain net product revenue milestones as described in the Loan Agreement
Illumina, Inc. [Member]
Debt Instrument [Line Items]
Loan interest rate, per annum									8.00%
Subordinated convertible promissory note issued									$ 5,000,000
Subordinated convertible promissory note maturity term					1 year
2012 Loan [Member]
Debt Instrument [Line Items]
Proceeds from the secured term loan	$ 11,300,000
2012 Loan [Member] | Series G Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Warrant to purchase stock, shares										167,182
Warrant to purchase of stock, per share										$ 21.78
Warrants exercisable period					2,019
2010 Loan [Member] | Series G Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Warrant to purchase stock, shares					17,215
Warrant to purchase of stock, per share					$ 21.78
Warrants exercisable period					2,017
Estimated fair value of warrants					$ 8,000

Debt - Summary of Aggregate Ann

Debt - Summary of Aggregate Annual Payments Net of Interest Due (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Less: current portion, net of debt discount and issuance costs	$ (2,866)	$ (5,961)
Long-term portion, net of debt discount and issuance costs	12,887	$ 5,451
Loan Agreement [Member]
Debt Instrument [Line Items]
Year ending December 31, 2016	3,021
Year ending December 31, 2017	6,309
Year ending December 31, 2018	6,670
Total remaining debt payments	16,000
Less: debt discount and issuance costs	(304)
Equals: debt principal balance as of December 31, 2015	15,696
Less: current portion, net of debt discount and issuance costs	(2,866)
Long-term portion, net of debt discount and issuance costs	$ 12,830

Warrants - Components of Common

Warrants - Components of Common Stock Warrants Outstanding (Detail) - Common Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Jan. 30, 2015
Class Of Warrant Or Right [Line Items]
Exercise Price		$ 6.96
Number of Shares Underlying Warrants	116,673
Class Of Warrant Or Right Issued on July 2006 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2006-07
Original Term	10 years
Exercise Price	$ 31.72
Number of Shares Underlying Warrants	17,656
Class Of Warrant Or Right Issued on November 2006 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2006-11
Original Term	10 years
Exercise Price	$ 31.72
Number of Shares Underlying Warrants	1,576
Class Of Warrant Or Right Issued on February 2008 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2008-02
Original Term	10 years
Exercise Price	$ 35.07
Number of Shares Underlying Warrants	22,792
Class Of Warrant Or Right Issued on August 2009 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2009-08
Original Term	10 years
Exercise Price	$ 21.78
Number of Shares Underlying Warrants	33,472
Class Of Warrant Or Right Issued on July 2010 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2010-07
Original Term	9 years
Exercise Price	$ 21.78
Number of Shares Underlying Warrants	6,694
Class Of Warrant Or Right Issued on January 2015 [Member]
Class Of Warrant Or Right [Line Items]
Issue Date	2015-01
Original Term	5 years
Exercise Price	$ 6.96
Number of Shares Underlying Warrants	34,483

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Detail) - USD ($)	Jan. 02, 2014	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 01, 2014	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised				$ 89,000
Fair market value of Company's common stock		$ 6.40		$ 6.40
Weighted average fair value of options to purchase common stock granted				$ 2.53	$ 4.81	$ 0.21
Total unrecognized stock-based compensation expense related to stock options and RSUs		$ 10,200,000		$ 10,200,000
Non-vested stock options and RSUs weighted average remaining period of recognition				2 years 9 months 18 days
Total fair value of options vested during period				$ 1,100,000
Shares available for grant		510,892		510,892	722,906	332,995		180,266
Share-based compensation expense, tax benefit recognized				$ 0	$ 0	$ 0
Share-based compensation costs, capitalized				0	0	0
Share based compensation, Total expensed				1,341,000	535,000	72,000
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, Total expensed				$ 812,000	390,000	$ 59,000
Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued				57,543
Fair value of shares issued				$ 349,000
Non Employee Director [Member] | General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, Total expensed				255,000	$ 94,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense related to stock options and RSUs		$ 2,400,000		$ 2,400,000
Non-vested stock options and RSUs weighted average remaining period of recognition				3 years
RSUs vest annual equal increments (in years)				4 years
RSUs granted period				2015-03
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance of common stock		838,695		838,695			357,075
Outstanding shares of common stock, in percentage	4.00%
2014 Equity Incentive Plan [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares may be added to the plan hereunder				865,252
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under ESPP		32,232	36,696
Proceeds from the issuance of shares				$ 400,000
Shares available for grant		186,473		186,473
Applicable exercise date an offering period shall be equal to percentage of the lesser of fair market value of common stock				85.00%

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Option Activity and Related Information (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Beginning Balance	722,906	332,995	180,266
Shares Available for Grant, Granted	(652,078)	(585,345)	(4,081)
Shares Available for Grant, Forfeited	77,660	20,591	7,247
Shares Available for Grant, Expired	5,329	13,781	149,563
Shares Available for Grant, Ending Balance	510,892	722,906	332,995
Shares Available for Grant, Additional options authorized	357,075	940,884
Shares Available for Grant, Assumed in business combination		0
Number of Shares, Beginning Balance	1,031,804	466,965	619,906
Number of Shares, Granted	652,078	585,345	4,081
Issuance of common stock for cash upon exercise of stock options, Shares	23,576	9,363	212
Number of Shares, Forfeited	(77,660)	(20,591)	(7,247)
Number of Shares, Expired	(5,329)	(13,781)	(149,563)
Number of Shares, Ending Balance	1,577,317	1,031,804	466,965
Number of Shares, Additional options authorized	0	0
Number of Shares, Assumed in business combination		23,229
Weighted-average Exercise Price, Beginning Balance	$ 7.36	$ 1.99	$ 2.67
Weighted-average Exercise Price, Granted	6.09	11.76	0.48
Weighted-average Exercise Price, Exercised	1.94	2.14	0.55
Weighted-average Exercise Price, Forfeited	8.13	10.36	2.33
Weighted-average Exercise Price, Expired	10.36	2.74	4.73
Weighted-average Exercise Price, Ending Balance	6.87	7.36	$ 1.99
Weighted-average Exercise Price, Additional options authorized	$ 0	0
Weighted-average Exercise Price, Assumed in business combination		$ 2.06

Stock Incentive Plans - Schedul

Stock Incentive Plans - Schedule of Outstanding, Exercisable and Vested Stock Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	$ 6.87	$ 7.36	$ 1.99	$ 2.67
Options Outstanding & Exercisable, Number of Options Outstanding	1,577,317
Options Outstanding & Exercisable, Weighted Average Remaining Contractual Life (Years)	7 years 11 months 1 day
Options Outstanding & Exercisable, Weighted Average Exercise Price	$ 6.87
Options Vested, Number of Options	679,993
Number of Options vested, Weighted Average Exercise Price	$ 5.75
$0.27-0.56 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding & Exercisable, Number of Options Outstanding	193,581
Options Outstanding & Exercisable, Weighted Average Remaining Contractual Life (Years)	6 years 9 months 18 days
Options Outstanding & Exercisable, Weighted Average Exercise Price	$ 0.55
Options Vested, Number of Options	166,699
Number of Options vested, Weighted Average Exercise Price	$ 0.55
$0.27-0.56 [Member] | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	0.27
$0.27-0.56 [Member] | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	$ 0.56
$2.05-3.06 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding & Exercisable, Number of Options Outstanding	135,656
Options Outstanding & Exercisable, Weighted Average Remaining Contractual Life (Years)	5 years 10 months 17 days
Options Outstanding & Exercisable, Weighted Average Exercise Price	$ 2.83
Options Vested, Number of Options	135,656
Number of Options vested, Weighted Average Exercise Price	$ 2.83
$2.05-3.06 [Member] | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	2.05
$2.05-3.06 [Member] | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	$ 3.06
$3.36-6.98 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding & Exercisable, Number of Options Outstanding	716,157
Options Outstanding & Exercisable, Weighted Average Remaining Contractual Life (Years)	8 years 3 months 11 days
Options Outstanding & Exercisable, Weighted Average Exercise Price	$ 5.68
Options Vested, Number of Options	127,859
Number of Options vested, Weighted Average Exercise Price	$ 3.84
$3.36-6.98 [Member] | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	3.36
$3.36-6.98 [Member] | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	$ 6.98
$7.03-12.44 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding & Exercisable, Number of Options Outstanding	531,923
Options Outstanding & Exercisable, Weighted Average Remaining Contractual Life (Years)	8 years 4 months 17 days
Options Outstanding & Exercisable, Weighted Average Exercise Price	$ 11.80
Options Vested, Number of Options	249,779
Number of Options vested, Weighted Average Exercise Price	$ 11.79
$7.03-12.44 [Member] | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	7.03
$7.03-12.44 [Member] | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Range of Exercise Prices	$ 12.44

Stock Incentive Plans - Summa55

Stock Incentive Plans - Summary of Options Outstanding Vested and Expected to Vest (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Vested | shares	679,993
Number of Shares, Expected to vest | shares	897,324
Number of Shares, Total | shares	1,577,317
Weighted-average Exercise Price, Vested | $ / shares	$ 5.75
Weighted-average Exercise Price, Expected to vest | $ / shares	7.71
Weighted-average Exercise Price, Total | $ / shares	$ 6.87
Weighted-average Remaining Contractual Life (Years), Vested	6 years 6 months 29 days
Weighted-average Remaining Contractual Life (Years), Expected to vest	8 years 11 months 12 days
Weighted-average Remaining Contractual Life (Years), Total	7 years 11 months 1 day
Aggregate Intrinsic Value, Vested | $	$ 1,788
Aggregate Intrinsic Value, Expected to vest | $	435
Aggregate Intrinsic Value, Total | $	$ 2,223

Stock Incentive Plans - Weighte

Stock Incentive Plans - Weighted-Average Assumptions Used to Fair Value of Share-Based Awards (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares of common stock subject to outstanding options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years	5 years 1 month 6 days	6 years
Expected volatility	41.17%	42.18%	45.25%
Risk-free interest rate	1.84%	1.69%	1.21%
Expected dividend yield	0.00%	0.00%	0.00%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months	0 years	0 years
Risk-free interest rate	0.11%	0.00%	0.00%
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility		0.00%	0.00%
Employee Stock Purchase Plan [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	39.10%
Employee Stock Purchase Plan [Member] | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	44.15%

Stock Incentive Plans - Summa57

Stock Incentive Plans - Summary of Unvested RSU Activity (Detail) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested beginning balance | shares	0
Number of Shares, Granted | shares	114,400
Number of Shares, Vested | shares	0
Number of Shares, Forfeited | shares	(8,200)
Number of Shares, Unvested ending balance | shares	106,200
Weighted Average Grant- Date Fair Value, Unvested beginning balance | $ / shares	$ 0
Weighted Average Grant- Date Fair Value, Granted | $ / shares	6.49
Weighted Average Grant- Date Fair Value, Vested | $ / shares	0
Weighted Average Grant- Date Fair Value, Forfeited | $ / shares	6.49
Weighted Average Grant- Date Fair Value, Unvested ending balance | $ / shares	$ 6.49

Stock Incentive Plans - Summa58

Stock Incentive Plans - Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	$ 1,341	$ 535	$ 72
Cost of testing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	109	28	3
Research and Development Expense [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	247	88	7
Sales and marketing [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	173	29	3
General and administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share based compensation, Total expensed	$ 812	$ 390	$ 59

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes Disclosure [Line Items]
Pretax net losses	$ (13,707,000)	$ (719,000)	$ (3,542,000)
Benefit for income taxes	0	(1,500,000)	0
Increase (decrease) in valuation allowance	3,700,000	(1,900,000)
Unrecognized tax benefits would impact the income tax provision	2,000,000	1,600,000
Accrued interest and penalties related to unrecognized tax benefits	0	0	$ 0
Federal [Member]
Income Taxes Disclosure [Line Items]
Deferred tax benefit		1,500,000
Net operating loss carryforwards	$ 174,300,000
Operating loss carryforwards, expiration year	2,018
Tax credit carryforwards	$ 3,600,000
Tax credit carryforwards, expiration year	2,021
State [Member]
Income Taxes Disclosure [Line Items]
Deferred tax benefit		$ 0
Net operating loss carryforwards	$ 115,900,000
Operating loss carryforwards, expiration year	2,016
State [Member] | California [Member]
Income Taxes Disclosure [Line Items]
Tax credit carryforwards	$ 4,400,000

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Difference between Benefit for Income Taxes and Income Taxes at Statutory U.S. Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation Nondeductible Expense Depreciation And Amortization [Abstract]
Federal tax at statutory rate	34.00%	34.00%	34.00%
Stock-based compensation	(1.90%)	(9.50%)	(11.40%)
Change in valuation allowance	(31.10%)	190.60%	(8.60%)
Change in unrecognized tax benefits	0.00%	0.00%	(8.40%)
Preferred stock warrant revaluation	(0.00%)	(0.70%)	(5.00%)
Interest expense	(0.00%)	(5.80%)	(0.00%)
Contingent liability for IMX acquisition	0.00%	38.20%	0.00%
Acquisition costs	(3.20%)	(36.70%)	(0.00%)
Other	2.20%	(1.30%)	(0.60%)
Effective income tax rate	0.00%	208.80%	0.00%

Income Taxes - Schedule of Tax

Income Taxes - Schedule of Tax Effects of Temporary Differences and Carryforwards that Rise to Significant Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 65,957	$ 63,116
Tax credit carryforwards	4,533	4,065
Accruals	1,125	942
Other	698	551
Gross deferred tax assets	72,313	68,674
Deferred tax liabilities:
Property and equipment	95	(8)
Purchased intangibles	(2,355)	(2,349)
Total deferred tax liabilities	(2,260)	(2,357)
Valuation allowance	(70,053)	(66,317)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Re62

Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Balance at beginning of year	$ 2,054	$ 2,196	$ 1,159
Additions based on tax positions related to current year	372	83	177
Additions (reductions) based on tax positions related to prior years	5	(225)	860
Balance at end of year	$ 2,431	$ 2,054	$ 2,196

401(K) Plan - Additional Inform

401(K) Plan - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Defined contribution plan, employer contribution	$ 0

Business Combination - Addition

Business Combination - Additional Information (Detail) - USD ($)	Jun. 10, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill acquired in business combination, estimated fair value		$ 12,005,000	$ 12,005,000
Stock-based compensation		$ 1,341,000	535,000	$ 72,000
ImmuMetrix, Inc. [Member]
Business Acquisition [Line Items]
Acquisition date		Jun. 10, 2014
Milestone description		the milestone will be achieved if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States no later than six years after the closing date of the acquisition.
Estimated purchase price	$ 17,200,000
Business acquisition purchase price, cash	600,000
Milestone measurement period		6 years
Goodwill acquired in business combination, estimated fair value	12,000,000
Estimated remaining useful life of patent		15 years
Business combination pro forma removal (addition) in income tax benefit			1,500,000	$ 1,500,000
ImmuMetrix, Inc. [Member] | CareDx, Inc [Member]
Business Acquisition [Line Items]
Acquisition-related costs			1,700,000
Stock-based compensation			200,000
ImmuMetrix, Inc. [Member] | In-process technology [Member]
Business Acquisition [Line Items]
Assets acquired in business combination, estimated fair value	6,700,000
Accumulated amortization of intangible asset		$ 0	0
ImmuMetrix, Inc. [Member] | Contingent consideration [Member]
Business Acquisition [Line Items]
Milestone description		The issuance will occur if the Company completes 2,500 commercial tests involving the measurement of dd-cfDNA in organ transplant recipients in the United States by June 10, 2020.
Shares issued, shares issuable upon achievement of future milestone, and options assumed		227,845
ImmuMetrix, Inc. [Member] | Series G Preferred Stock [Member]
Business Acquisition [Line Items]
Estimated fair value	$ 14,200,000
Shares issued, shares issuable upon achievement of future milestone, and options assumed	911,364
ImmuMetrix, Inc. [Member] | Series G Preferred Stock [Member] | Shares of common stock subject to outstanding options [Member]
Business Acquisition [Line Items]
Estimated fair value	$ 369,000
Shares issued, shares issuable upon achievement of future milestone, and options assumed	23,229
ImmuMetrix, Inc. [Member] | Series G Preferred Stock [Member] | Contingent consideration [Member]
Business Acquisition [Line Items]
Estimated fair value	$ 2,300,000	$ 900,000	$ 1,100,000
Shares issued, shares issuable upon achievement of future milestone, and options assumed	227,845

Business Combination - Schedule

Business Combination - Schedule of Pro Forma Results of Operations (Detail) - ImmuMetrix, Inc. [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Net revenue	$ 27,306	$ 22,098
Net loss	$ (1,080)	$ (3,768)
Net loss per common share - basic	$ (0.19)	$ (3.73)
Net loss per common share - diluted	$ (0.19)	$ (3.73)

Selected Quarterly Financial 66

Selected Quarterly Financial Data - Summary of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 6,648	$ 7,151	$ 7,129	$ 7,216	$ 7,952	$ 6,654	$ 6,776	$ 5,924	$ 28,144	$ 27,306	$ 22,098
Net (loss) income	$ (4,761)	$ (3,489)	$ (3,185)	$ (2,272)	$ (5)	$ 1,213	$ 877	$ (1,304)	$ (13,707)	$ 781	$ (3,542)
Net (loss) income per common share, basic	$ (0.40)	$ (0.29)	$ (0.27)	$ (0.19)	$ 0	$ 0.13	$ 0.87	$ (1.29)	$ (1.16)	$ 0.13	$ (3.50)
Net (loss) income per common share, diluted	$ (0.40)	$ (0.29)	$ (0.27)	$ (0.19)	$ 0	$ 0.12	$ 0.13	$ (1.29)	$ (1.16)	$ 0.10	$ (3.50)
Shares used in calculation of net (loss) income per share, basic	11,902,325	11,890,057	11,835,405	11,814,467	11,802,241	9,279,649	1,013,128	1,011,980	11,860,885	5,815,928	1,010,795
Shares used in calculation of net (loss) income per share, diluted	11,902,325	11,890,057	11,835,405	11,814,467	11,802,241	11,219,377	6,939,568	1,011,980	11,860,885	9,283,001	1,010,795