upon full exercise of the underwriters’ option to purchase additional shares of common stock resulting in net proceeds of $93.3 million after deducting underwriting discounts and commissions and offering expenses. On July 1, 2020, we entered into an Open Market Sale Agreement (the “ATM Agreement”) with Jefferies LLC (Jefferies”) with respect to an at-the-market offering program under which the we may offer and sell, from time to time at its sole discretion, shares of our common stock, having an aggregate offering price of up to $75,000,000, referred to as Placement Shares, through Jefferies as its sales agent. During the three months ended September 30, 2020, we issued and sold 256,879 shares of common stock for the net proceeds of $6.3 million under the ATM. Refer to Note 8 of the accompanying condensed consolidated financial statements appearing elsewhere in this Quarterly Report on Form 10-Q for details.
Since inception, our operations have focused on organizing and staffing our company, business planning, raising capital, establishing our intellectual property portfolio, and performing research to discover and develop oral small-molecule integrin therapeutics. Revenue generation activities have been limited to the following: in October 2018, pursuant to the AbbVie Agreement, we received an upfront payment of $100.0 million for research and development activities, and in September 2020 we received $20.0 million in connection with AbbVie exercising its option to license the selective αvβ6-specific integrin inhibitors program; in March 2019, pursuant to the Janssen Agreement, we received an upfront payment of $10.0 million and provided Janssen with exclusive license options on product candidates directed at multiple targets; in addition, Janssen will reimburse us for research services at market rates. We do not have any products approved for sale and have not generated any revenue from product sales. Through September 30, 2020 in addition to the foregoing sources of revenue, we have funded our operations primarily through the sale and issuance of our convertible preferred equity securities, borrowings under a loan and security agreement (the “credit facility”) with Silicon Valley Bank (“SVB”), our IPO, and sales of shares of our common stock pursuant to the ATM Agreement. From inception through September 30, 2020 we raised an aggregate of approximately $249.5 million of gross proceeds through the issuance of equity and debt.
Since inception, we have incurred significant operating losses. As of September 30, 2020, we had an accumulated deficit of $124.8 million. We expect to continue to incur significant and increasing expenses and operating losses for the foreseeable future, as we advance our current and future product candidates through preclinical and clinical development, seek regulatory approval for them, maintain and expand our intellectual property portfolio, hire additional research and development and business personnel, and operate as a public company.
We will not generate revenue from product sales unless and until we successfully complete clinical development and obtain regulatory approval for our product candidates. In addition, if we obtain regulatory approval for our product candidates and do not enter into a third-party commercialization partnership, we expect to incur significant expenses related to developing our commercialization capability to support product sales, marketing, manufacturing, and distribution activities.
As a result, we will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until we can generate significant revenue from product sales, if ever, we expect to finance our operations through a combination of public or private equity offerings and debt financings or other sources, such as additional collaboration agreements. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on acceptable terms, or at all. Our failure to raise capital or enter into such agreements as, and when, needed, could have a material adverse effect on our business, results of operations, and financial condition.
As of September 30, 2020, we had cash, cash equivalents, and marketable securities of $213.1 million. We believe that our existing cash and cash equivalents, marketable securities will enable us to fund our operating expenses and capital expenditure requirements through at least the end of 2022.
Impact of the COVID-19 Pandemic
The extent of the impact of the novel strain of coronavirus, SARS-CoV-2 (“COVID-19”) on our operational and financial performance will depend on certain developments, including the duration and spread of the outbreak, impact on our preclinical studies, employee or industry events, and effect on our suppliers and manufacturers, all of which are uncertain and cannot be predicted. The COVID-19 pandemic and its adverse effects have become more prevalent in the locations where we, our collaborators, our contract research organizations (“CROs”), suppliers or third-party business partners conduct business. Although we currently have not experienced much impact on our business, including our