Common Stock	9 Months Ended
Jan. 31, 2021
Equity [Abstract]
Common Stock	(12) Common Stock At the Market Offering Agreements On January 7, 2019, the Company entered into the 2019 ATM Facility with AGP, under which the Company may issue and sell to or through A.G.P./Alliance Global Partners, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $25.0 million. From inception of the program through its termination on December 8, 2020, under the 2019 ATM Facility the Company had sold and issued an aggregate of 17,595,472 shares of its common stock with an aggregate market value of $23.4 million at an average price of $1.33 per share, including 12,342,506 shares in fiscal year 2021 with an aggregate market value of $18.7 million at an average price of $1.51 per share and paid AGP a sales commission of approximately $0.8 million related to those shares. The agreement was fully utilized and terminated on December 8, 2020. On November 20, 2020, the Company entered into a new At the Market Offering Agreement with AGP (the “2020 ATM Facility”). The Company on December 4, 2020 filed a prospectus with Securities and Exchange Commission whereby, the Company may issue and sell to or through AGP, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $50.0 million. From inception of the 2020 ATM Facility through January 31, 2021, the Company had sold and issued an aggregate of 17,179,883 shares of its common stock with an aggregate market value of $50.0 million at an average price of $2.91 per share and paid AGP a sales commission of approximately $1.6 million related to those shares. The dollar amount reported in the prospectus filing is fully utilized. Equity Line Common Stock Purchase Agreements On October 24, 2019, the Company entered into a common stock purchase agreement with Aspire Capital which provided that, subject to certain terms, conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over a 30-month period. Through September 18, 2020, the Company has sold an aggregate of 6,424,205 shares of common stock with an aggregate market value of $4.0 million at an average price of $0.63 per share pursuant to this common stock purchase agreement, including 5,025,000 shares in fiscal year 2021 with an aggregate market value of $2.9 million at an average price of $0.57 per share. The agreement was fully utilized and terminated on September 18, 2020. On September 18, 2020, the Company entered into a new common stock purchase agreement with Aspire Capital which provided that, subject to certain terms, conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $12.5 million of shares of the Company’s common stock over a 30-month period that does not exceed 19.99% of the outstanding common stock on the date of the agreement. The number of shares the Company could issue within the 19.99% limit is 3,722,251 shares without shareholder approval. Shareholder approval was received at the Company’s annual meeting of stockholders on December 23, 2020 for the sale of 9,864,706 additional shares of common stock which is over the 19.99% limit of the outstanding common stock on the date of the agreement. Through January 31, 2021, the Company has sold an aggregate of 2,250,000 shares of common stock with an aggregate market value of $7.4 million at an average price of $3.28 per share pursuant to this common stock purchase agreement.

Common Stock

9 Months Ended

Jan. 31, 2021

(12) Common Stock

At the Market Offering Agreements

On January 7, 2019, the Company entered into the 2019 ATM Facility with AGP, under which the Company may issue and sell to or through A.G.P./Alliance Global Partners, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $25.0 million. From inception of the program through its termination on December 8, 2020, under the 2019 ATM Facility the Company had sold and issued an aggregate of 17,595,472 shares of its common stock with an aggregate market value of $23.4 million at an average price of $1.33 per share, including 12,342,506 shares in fiscal year 2021 with an aggregate market value of $18.7 million at an average price of $1.51 per share and paid AGP a sales commission of approximately $0.8 million related to those shares. The agreement was fully utilized and terminated on December 8, 2020.

On November 20, 2020, the Company entered into a new At the Market Offering Agreement with AGP (the “2020 ATM Facility”). The Company on December 4, 2020 filed a prospectus with Securities and Exchange Commission whereby, the Company may issue and sell to or through AGP, acting as agent and/or principal, shares of the Company’s common stock having an aggregate offering price of up to $50.0 million. From inception of the 2020 ATM Facility through January 31, 2021, the Company had sold and issued an aggregate of 17,179,883 shares of its common stock with an aggregate market value of $50.0 million at an average price of $2.91 per share and paid AGP a sales commission of approximately $1.6 million related to those shares. The dollar amount reported in the prospectus filing is fully utilized.

Equity Line Common Stock Purchase Agreements

On October 24, 2019, the Company entered into a common stock purchase agreement with Aspire Capital which provided that, subject to certain terms, conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $10.0 million of shares of the Company’s common stock over a 30-month period. Through September 18, 2020, the Company has sold an aggregate of 6,424,205 shares of common stock with an aggregate market value of $4.0 million at an average price of $0.63 per share pursuant to this common stock purchase agreement, including 5,025,000 shares in fiscal year 2021 with an aggregate market value of $2.9 million at an average price of $0.57 per share. The agreement was fully utilized and terminated on September 18, 2020.

On September 18, 2020, the Company entered into a new common stock purchase agreement with Aspire Capital which provided that, subject to certain terms, conditions and limitations, Aspire Capital is committed to purchase up to an aggregate of $12.5 million of shares of the Company’s common stock over a 30-month period that does not exceed 19.99% of the outstanding common stock on the date of the agreement. The number of shares the Company could issue within the 19.99% limit is 3,722,251 shares without shareholder approval. Shareholder approval was received at the Company’s annual meeting of stockholders on December 23, 2020 for the sale of 9,864,706 additional shares of common stock which is over the 19.99% limit of the outstanding common stock on the date of the agreement. Through January 31, 2021, the Company has sold an aggregate of 2,250,000 shares of common stock with an aggregate market value of $7.4 million at an average price of $3.28 per share pursuant to this common stock purchase agreement.