The Company has authorized 150,000,000 shares of common stock, $0.0001 par value per share, of which 72,490,449 shares, and 64,672,893 shares were issued and outstanding as of March 31, 2020, and 2019, respectively.

On January 30, 2019, the Company consummated an underwritten public offering of shares of its common stock pursuant to which the Company sold an aggregate of 6,198,500 shares of its common stock, including 808,500 shares sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a purchase price of $6.50 per share with gross proceeds to the Company totaling $40,290,250, less issuance costs incurred of approximately $2.6 million.

On February 11, 2020, the Company consummated an underwritten public offering of shares of its common stock pursuant to which the Company sold an aggregate of 7,666,667 shares of its common stock, including 1,000,000 shares sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a purchase price of $6.00 per share with gross proceeds to the Company totaling $46.0 million, less estimated issuance costs incurred of approximately $3.0 million.

During the three months ended March 31, 2020 and 2019, the Company issued 150,889 and 61,771 shares of common stock upon the exercise of stock options to purchase common stock and the Company received proceeds of $15,944 and $204,003 from these exercises, respectively. During the three months ended March 31, 2019, warrants to purchase 1,083,500 shares of common stock were exercised on a cashless basis resulting in the issuance of 947,454 shares of common stock. No warrants were exercised during the three months ended March 31, 2020.