Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2014

Assets and Liabilities Measured at Fair Value on a Recurring Basis

Assets and liabilities measured at fair value on a recurring basis at March 31, 2014 and December 31, 2013 are as follows (in thousands):



	Fair Value Measurements at Reporting Date Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)	Significant Unobservable Inputs (Level 3)	Total
At March 31, 2014
Assets
Cash equivalents⁽¹⁾	$	46,725	—	—	$	46,725
Liabilities
Common stock warrant liabilities⁽²⁾	$	—	—	22,156	$	22,156
Embedded derivative liabilities⁽³⁾	$	—	—	247	$	247
At December 31, 2013
Assets
Cash equivalents⁽¹⁾	$	69,120	—	—	$	69,120
Liabilities
Common stock warrant liabilities⁽²⁾	$	—	—	31,341	$	31,341
Embedded derivative liabilities⁽³⁾	$	—	—	233	$	233


(1)	Cash equivalents are comprised of money market fund shares and are included as a component of cash and cash equivalents on the consolidated balance sheets.

(2)

Common stock warrant liabilities include liabilities associated with warrants issued in connection with the Company's July 2012 public offering of common stock and warrants (see Note 5) and warrants issued in connection with the Healthcare Royalty financing agreement (see Note 4), which are measured at fair value using the Black-Scholes option pricing valuation model. The assumptions used in the Black-Scholes option pricing valuation model for both common stock warrant liabilities were: (a) a risk-free interest rate based on the rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the remaining contractual term of the warrants; (b) an assumed dividend yield of zero based on the Company’s expectation that it will not pay dividends in the foreseeable future; (c) an expected term based on the remaining contractual term of the warrants; and (d) given the Company’s lack of relevant historical data due to the Company’s limited historical experience, an expected volatility based upon the Company's historical volatility, supplemented with historical volatility of comparable companies whose share prices have been publicly available for a sufficient period of time. The significant unobservable input used in measuring the fair value of the common stock warrant liabilities associated with the Healthcare Royalty financing agreement is the expected volatility. Significant increases in volatility would result in a higher fair value measurement. The following additional assumptions were used in the Black-Scholes option pricing valuation model to measure the fair value of the warrants sold in the July 2012 public offering: (a) management's projections regarding the probability of the occurrence of an extraordinary event and the timing of such event; and for the valuation scenario in which an extraordinary event occurs that is not an all cash transaction or an event whereby a public acquirer would assume the warrants, (b) an expected volatility rate using the Company's historical volatility, supplemented with historical volatility of comparable companies, through the projected date of public announcement of an extraordinary transaction, blended with a rate equal to the lesser of 40% and the 180-day volatility rate obtained from the HVT function on Bloomberg as of the trading day immediately following the public announcement of an extraordinary transaction. The significant unobservable inputs used in measuring the fair value of the common stock warrant liabilities associated with the July 2012 public offering are the expected volatility and the probability of the occurrence of an extraordinary event. Significant increases in volatility would result in a higher fair value measurement and significant increases in the probability of an extraordinary event occurring would result in a significantly lower fair value measurement. The decrease in the fair value of the common stock warrant liabilities as of March 31, 2014 was primarily driven by the decrease in the Company's stock price at March 31, 2014 as compared against December 31, 2013 measurement dates.

(3)

Embedded derivatives are measured at fair value using various discounted cash flow valuation models are included as a component of other long-term liabilities on the consolidated balance sheets. The assumptions used in the discounted cash flow valuation models include: (a) management's revenue projections and a revenue sensitivity analysis based on possible future outcomes; (b) probability weighted net cash flows based on the likelihood of Healthcare Royalty receiving interest payments over the term of the Healthcare Royalty financing agreement; (c) probability of bankruptcy; (d) weighted average cost of capital that included the addition of a company specific risk premium to account for uncertainty associated with the Company achieving future cash flows; (e) the probability of a change in control occurring during the term of the Healthcare Royalty financing agreement; and (f) the probability of an exercise of the embedded derivative instruments. The significant unobservable inputs used in measuring the fair value of the embedded derivatives are management’s revenue projections. Significant decreases in these significant inputs would result in a higher fair value measurement of the liability.

Reconciliation of Liabilities Measured at Fair Value Using Significant Observable Inputs (Level 3)

The following table provides a reconciliation of liabilities measured at fair value using significant observable inputs (Level 3) for the three months ended March 31, 2014 (in thousands):



	Common Stock Warrant Liabilities			Embedded Derivative Liabilities
Balance at December 31, 2013	$	31,341		$	233
Changes in fair value	(8,269		)	14
Exercises	$	(916	)	$	—
Balance at March 31, 2014	$	22,156		$	247

Basic and Diluted Net Loss Per Share

The following table presents the computation of basic and diluted net loss per share (in thousands, except per share amounts):



	Three Months Ended March 31,
	2014			2013
Numerator
Net loss for basic EPS	$	(20,932	)	$	(21,055	)

Effect of dilutive securities:
Common stock warrants	$	(8,269	)	$	—
Non-employee stock options and restricted stock units	(132		)	—
	$	(8,401	)	$	—

Net loss for diluted EPS	$	(29,333	)	$	(21,055	)

Denominator
Weighted average common shares outstanding, basic	139,309			100,809

Effect of dilutive securities:
Common stock warrants	5,870			—
Non-employee stock options and restricted stock units	144			—
Dilutive potential shares of common stock	6,014			—

Weighted average common shares outstanding, diluted	145,323			100,809

Basic net loss per share	$	(0.15	)	$	(0.21	)
Diluted net loss per share	$	(0.20	)	$	(0.21	)

Schedule of Calculation of Diluted Net Loss Per Share

The following table presents potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive (in thousands, of common equivalent shares):



	Three Months Ended March 31,
	2014	2013
Common stock options and restricted stock units	11,246	123
Common stock warrants	508	—
	11,754	123

- Definition

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

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