CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
REVENUES:
Contract manufacturing revenue	$ 44,357,000	$ 26,744,000	$ 22,294,000
License revenue	329,000	37,000	107,000
Total revenues	44,686,000	26,781,000	22,401,000
COSTS AND EXPENSES:
Cost of contract manufacturing	22,966,000	15,593,000	13,110,000
Research and development	59,529,000	42,996,000	27,723,000
Selling, general and administrative	18,551,000	18,691,000	17,274,000
Total costs and expenses	101,046,000	77,280,000	58,107,000
LOSS FROM OPERATIONS	(56,360,000)	(50,499,000)	(35,706,000)
OTHER INCOME (EXPENSE):
Interest and other income	722,000	142,000	349,000
Interest and other expense	(14,000)	(1,000)	(5,000)
NET LOSS	(55,652,000)	(50,358,000)	(35,362,000)
COMPREHENSIVE LOSS	(55,652,000)	(50,358,000)	(35,362,000)
Series E preferred stock accumulated dividends	(4,484,000)	(3,696,000)	(401,000)
NET LOSS ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ (60,136,000)	$ (54,054,000)	$ (35,763,000)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING: Basic and Diluted	216,265,620	182,558,332	161,579,649
BASIC AND DILUTED LOSS PER COMMON SHARE	$ (.28)	$ (0.30)	$ (0.22)