5. STOCKHOLDERS’ EQUITY (Tables)

6 Months Ended

Jun. 30, 2018

Equity [Abstract]

Schedule of assumptions

	Six Months Ended June 30,
	2018		2017
Expected term		5.8 - 6.3 years		5.8 - 6.3 years
Volatility		54-57%		51-64%
Dividend yield		0.0		0.0
Risk-free interest rate		2.40-2.59%		1.77-2.29%

Schedule of stock option activity

	Six Months Ended
	June 30, 2018
	Shares			Weighted Average Exercise Price
Outstanding at beginning of period		3,276,043		$	5.52
Forfeited		(23,185	)	$	4.24
Expired		(2,334	)	$	2.68
Granted		1,002,900		$	3.87
Exercised		(1,959	)	$	2.68
Outstanding at end of period and expected to vest		4,251,465		$	5.14
Options exercisable		1,842,738		$	6.76

Stock-based compensation expense

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2018		2017		2018		2017
Research and development	$	83,339	$	68,434	$	161,644	$	121,417
Plasma centers		7,760		13,196		14,846		25,947
Selling, general and administrative		406,193		223,973		801,050		394,116
Cost of product revenue		38,099		5,760		72,635		5,760
Total stock-based compensation expense	$	535,391	$	311,363	$	1,050,175	$	547,240