7. STOCKHOLDERS' EQUITY

6 Months Ended

Oct. 31, 2013

Equity [Abstract]

7. STOCKHOLDERS' EQUITY

Sales of Common Stock

Our ability to continue our clinical trials and development efforts is highly dependent on the amount of cash and cash equivalents on hand combined with our ability to raise additional capital to support our future operations through one or more methods, including but not limited to, issuing additional equity.

With respect to financing our operations through the issuance of equity, on December 27, 2012, we entered into an At Market Sales Issuance Agreement (“December 2012 AMI Agreement”) with MLV & Co. LLC (“MLV”), pursuant to which we may sell shares of our common stock through MLV, as agent, for aggregate gross proceeds of up to $75,000,000, in registered transactions from our shelf registration statement on Form S-3 (File No. 333-180028). During the six months ended October 31, 2013, we sold 15,938,269 shares of common stock at market prices under the December 2012 AMI Agreement for aggregate gross proceeds of $24,277,000 before deducting commissions and other issuance costs of $722,000. As of October 31, 2013, aggregate gross proceeds of up to $37,351,000 remained available under the December 2012 AMI Agreement.

Shares of Common Stock Authorized and Reserved for Future Issuance

As of October 31, 2013, we had reserved 29,858,569 additional shares of our common stock, which may be issued under our equity compensation plans and outstanding warrant agreements, excluding shares of common stock that could potentially be issued under our current effective shelf registration statement, as further described in the following table:

	Number of Shares Reserved
Common shares reserved for issuance under outstanding option grants and common shares available for issuance under our stock incentive plans		26,306,989
Common shares reserved for and available for issuance under our Employee Stock Purchase Plan		3,176,777
Common shares issuable upon exercise of outstanding warrants		374,803
Total shares of common stock reserved for issuance		29,858,569