Warrants

In connection with certain of the Company’s collaboration agreements and consulting arrangements, the Company has issued warrants to purchase shares of common stock as payment for services. As of each of March 31, 2020 and December 31, 2019, collaboration warrants to purchase 32,412 shares of common stock were outstanding. These warrants have an average weighted exercise price of $136.45 and expiration dates ranging from May 2020 through May 2021. No collaboration warrants were granted or exercised in connection with collaboration or consulting services during the three months ended March 31, 2020 and 2019, respectively.

In addition, the Company has outstanding warrants to purchase an aggregate of 439,083 and 658,557 shares of common stock in connection with debt and equity financing arrangements as of March 31, 2020 and December 31, 2019, respectively. These warrants have an average weighted exercise price of $40.24 and $31.16 as of March 31, 2020 and December 31, 2019, respectively, and expiration dates ranging from July 2020 through September 2026. There were no debt and equity financing warrants granted during the three months ended March 31, 2020, and warrants to purchase 129,084 shares of common stock were granted during the three months ended March 31, 2019. During the three months ended March 31, 2020, debt and equity financing warrants to purchase approximately 219,000 shares of common stock were exercised on a cashless one-for-one basis. No debt or equity financing warrants were exercised during the three months ended March 31, 2019.