CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
REVENUES:
Contract manufacturing revenue	$ 21,333,000	$ 14,783,000	$ 8,502,000
Government contract revenue	0	0	4,640,000
License revenue	350,000	450,000	350,000
Total revenues	21,683,000	15,233,000	13,492,000
COSTS AND EXPENSES:
Cost of contract manufacturing	12,595,000	10,153,000	7,296,000
Research and development	24,306,000	35,688,000	29,462,000
Selling, general and administrative	13,134,000	11,462,000	11,421,000
Total costs and expenses	50,035,000	57,303,000	48,179,000
LOSS FROM OPERATIONS	(28,352,000)	(42,070,000)	(34,687,000)
OTHER INCOME (EXPENSE):
Interest and other income	322,000	41,000	1,052,000
Interest and other expense	(54,000)	(90,000)	(516,000)
Loss on early extinguishment of debt	(1,696,000)	0	0
NET LOSS	(29,780,000)	(42,119,000)	(34,151,000)
COMPREHENSIVE LOSS	$ (29,780,000)	$ (42,119,000)	$ (34,151,000)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING	120,370,333	83,572,761	60,886,392
BASIC AND DILUTED LOSS PER COMMON SHARE	$ (0.25)	$ (0.50)	$ (0.56)