Net loss attributable to Heat Biologics, Inc. We had a net loss attributable to Heat Biologics, Inc. of $10.7 million, or ($0.15) per basic and diluted share for the six months ended June 30, 2020 compared to a net loss of $10.5 million, or ($0.32) per basic and diluted share for the six months ended June 30, 2019.
LIQUIDITY AND CAPITAL RESOURCES
Sources of Liquidity
Since our inception in June 2008, we have incurred significant losses and we have financed our operations with net proceeds from the private placement of our preferred stock, common stock and debt. Since our initial public offering, we have primarily financed our operations with net proceeds from the public offering of our securities and to a lesser extent, the proceeds from the exercise of warrants. During May 2018, we closed a public offering of shares of our common stock and warrants to purchase shares of our common stock in which we received net proceeds of approximately $18.8 million and after the closing of the offering, an additional $4.8 million from the exercise of 3,054,667 warrants issued in this offering. During November 2018, we closed a public offering of shares of our common stock and warrants to purchase shares of our common stock in which we received net proceeds of approximately $12.7 million. For the year ended December 31, 2018, we received net proceeds of approximately $3.8 million from sales of our common stock in at-the-market offerings. On January 21, 2020, we closed an underwritten public offering of shares of our common stock and warrants to purchase shares of our common stock pursuant to which we received net proceeds of approximately $6.4 million. For the six months ended June 30, 2020, we received net proceeds of $36 million from the sale of 44,864,076 shares of our common stock in at-the-market offerings. As of June 30, 2020, we had an accumulated deficit of $115.3 million. We had net losses of $20.4 million and $16.6 million for the years ended December 31, 2019 and 2018, respectively. We had net losses of $10.9 million and $10.8 million for the six months ended June 30, 2020 and 2019, respectively. Subsequent to the quarter ended June 30, 2020, we have issued an additional 36,111,471 shares of common stock in “at-the-market” offerings and received $58.5 million of net proceeds.
We expect to incur significant expenses and continued losses from operations for the foreseeable future. We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the research and development and advance our clinical trials of, and seek marketing approval for, our product candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing, and distribution. Although we currently have sufficient funds to complete our Phase 2 clinical trials, as currently planned, and expect that we will have sufficient funds to fund our operations into the third quarter 2021, we will need to obtain substantial additional future funding in connection with our future planned clinical trials. While we are currently funding vaccine development and preclinical studies, we do not expect to use significant corporate resources to advance our COVID-19 program. We are applying for several large grants to support clinical development of this program and are engaged in collaboration discussions, which we believe may provide attractive and non-dilutive pathways to help accelerate development of our COVID-19 program; however, there can be no assurance that we will receive such grant funding or if received, the amount of such grant funding. Adequate additional financing may not be available to us on acceptable terms, or at all. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce or eliminate our research and development programs or any future commercialization efforts. To meet our capital needs, we are considering multiple alternatives, including, but not limited to, additional equity financings, which include sales of our common stock under at-the-market offerings, if available, debt financings, partnerships, collaborations and other funding transactions. This is based on our current estimates, and we could use our available capital resources sooner than we currently expect. We may take additional action to reduce our immediate cash expenditures, including revisiting our headcount, offering vendors equity in lieu of the cash due to them and otherwise limiting our other research expenses, in order to focus our resources on our product candidates. We will need to generate significant revenues to achieve profitability, and we may never do so. As of June 30, 2020, we had approximately $47.0 million in cash and cash equivalents and short-term investments.
Cash Flows
Operating activities. Net cash used in operating activities during the six months ended June 30, 2020 was $10.1 million compared to $8.2 million during the same period in 2019. Net cash used in operating activities primarily reflects the net