7. EQUITY COMPENSATION PLANS

6 Months Ended

Oct. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

EQUITY COMPENSATION PLANS

Stock Incentive Plans

As of October 31, 2016, we had an aggregate of 39,525,245 shares of our common stock reserved for issuance under our stock incentive plans, of which 29,674,529 shares were subject to outstanding options and 9,850,716 shares were available for future grants of share-based awards.

The following summarizes our stock option transaction activity for the six months ended October 31, 2016:

Stock Options	Shares			Weighted Average Exercisable Price
Outstanding, May 1, 2016		23,751,261		$	1.48
Granted		6,856,384		$	0.49
Exercised		–			–
Canceled or expired		(933,116	)	$	1.14
Outstanding, October 31, 2016		29,674,529		$	1.26

Employee Stock Purchase Plan

We have reserved a total of 15,000,000 shares of our common stock to be purchased under our ESPP, of which 10,520,626 shares remained available to purchase at October 31, 2016. The ESPP allows eligible employees on a voluntary basis to purchase shares of our common stock directly from us. Under the ESPP, we sell shares to participants at a price equal to the lesser of 85% of the fair market value of our common stock at the (i) beginning of a six-month offering period, or (ii) end of the six-month offering period. The ESPP provides for two six-month offering periods each year; the first offering period begins on the first trading day on or after each November 1; the second offering period begins on the first trading day on or after each May 1. During the six months ended October 31, 2016, 888,033 shares of our common stock were purchased under the ESPP at a purchase price of $0.29 per share.

Share-Based Compensation

Total share-based compensation expense related to share-based awards issued under our equity compensation plans is included in the accompanying unaudited condensed consolidated statements of operations as follows:

	Three Months Ended October 31,				Six Months Ended October 31,
	2016		2015		2016		2015
Cost of contract manufacturing	$	24,000	$	9,000	$	66,000	$	22,000
Research and development		446,000		569,000		816,000		1,040,000
Selling, general and administrative		415,000		696,000		840,000		1,395,000
Total	$	885,000	$	1,274,000	$	1,722,000	$	2,457,000
Share-based compensation from:
Stock options	$	823,000	$	1,223,000	$	1,554,000	$	2,347,000
ESPP		62,000		51,000		168,000		110,000
	$	885,000	$	1,274,000	$	1,722,000	$	2,457,000

As of October 31, 2016, the total estimated unrecognized compensation cost related to non-vested employee stock options was $3,844,000. This cost is expected to be recognized over a weighted average vesting period of 1.68 years based on current assumptions.