Share-Based Payments (Tables)

9 Months Ended

Sep. 30, 2012

Share-Based Payments

Schedule of stock-based compensation recognized related to the grant of employee and non-employee stock options, and non-vested stock

	Year Ended December 31,							Nine Months Ended September 30,
	2009		2010		2011			2011			2012
								(unaudited)
	(in thousands)
Research and development	$	28	$	53	$	63		$	44		$	133
Selling, general and administrative		83		244		(145	)		(88	)		139
Total	$	111	$	297	$	(82	)	$	(44	)	$	272

Schedule of assumptions used in estimation of fair value of each award option on the date of grant using Black-Scholes option-pricing model

	Year Ended December 31,			Nine Months Ended September 30,
	2009	2010	2011	2011	2012
				(unaudited)
Fair value of common stock	$1.60 - $7.04	$2.56 - $3.36	$4.24 - $5.88	—	$5.07 - $12.92
Expected volatility	60.3% - 61.5%	59.1% - 74.7%	69.1% - 69.5%	—	68.3% - 71.6%
Expected dividends	0%	0%	0%		0%
Expected term	6.25 years	0.41 - 6.25 years	6.25 years	—	6.25 years
Risk-free rate	1.65% - 2.72%	0.15% - 2.93%	1.16% - 1.49%	—	0.96% - 1.14%
Expected forfeiture rate	5%	0% - 5%	0%	—	0%

Schedule of stock options granted to employees and non-employees

Grant Date	Number of Options Granted		Exercise Price		Estimated Fair Value		Intrinsic Value
01/19/2009		56,250	$	1.60	$	0.93	$	—
12/15/2009		64,300	$	7.04	$	4.13	$	—
02/10/2010		13,125	$	3.36	$	1.96	$	—
04/16/2010		8,186	$	3.36	$	1.95	$	—
07/20/2010		9,625	$	3.36	$	1.93	$	—
10/15/2010		3,750	$	2.56	$	1.48	$	—
11/02/2010		220,000	$	2.56	$	1.64	$	—
11/16/2010		8,750	$	2.56	$	1.65	$	—
10/14/2011		8,750	$	4.24	$	2.68	$	—
12/30/2011		136,000	$	5.88	$	3.68	$	—
1/17/2012 (unaudited)		5,686	$	5.88	$	3.68	$	—
5/2/2012 (unaudited)		24,325	$	5.74	$	3.56	$	—
6/21/2012 (unaudited)		13,250	$	5.07	$	3.24	$	—
8/9/2012 (unaudited)		95,000	$	12.92	$	8.28	$	—

Summary of stock option activity

	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term
Outstanding, December 31, 2010		664,479		$	1.72		7.83
Granted		144,750		$	5.80
Exercised		(69,559	)	$	0.40
Forfeited or expired		(141,561	)	$	2.17
Outstanding, December 31, 2011		598,109		$	2.75		7.71
Granted (unaudited)		138,261		$	10.61
Exercised (unaudited)		(104,480	)	$	1.58
Forfeited or expired (unaudited)		(57,064	)	$	2.45
Outstanding, September 30, 2012 (unaudited)		574,826		$	4.89		7.78
As of December 31, 2011:
Vested and expected to vest		588,586		$	2.76		7.70
Exercisable		262,568		$	1.29		5.96
As of September 30, 2012 (unaudited):
Vested and expected to vest (unaudited)		569,563		$	4.91		7.77
Exercisable (unaudited)		187,657		$	1.24		5.07

Summary of activity related to non-vested shares

	Number of Shares			Weighted- Average Fair Value
Non-vested shares, December 31, 2010		102,941		$	0.40
Granted		—
Vested		—
Forfeited or expired		(102,941	)	$	0.40
Non-vested shares, December 31, 2011		—