9. SEGMENT REPORTING (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Segment Reporting [Abstract]
Contract manufacturing services revenue	$ 6,672,000	$ 5,677,000	$ 25,574,000	$ 17,436,000
Cost of contract manufacturing services	3,896,000	3,113,000	13,245,000	10,835,000
Gross profit	2,776,000	2,564,000	12,329,000	6,601,000
Revenue from products in research and development	37,000	0	329,000	37,000
Research and development expense	(15,156,000)	(11,261,000)	(43,264,000)	(31,465,000)
Selling, general and administrative expense	(4,524,000)	(4,325,000)	(13,839,000)	(13,503,000)
Other income (expense), net	20,000	28,000	677,000	107,000
Net loss	$ (16,847,000)	$ (12,994,000)	$ (43,768,000)	$ (38,223,000)