accounting impact on our business, please read Note C, “Significant Collaborative Agreements,” to our consolidated financial statements included in this report and in our Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on March 11, 2020.
To date, we have not generated revenues from commercial sales of internal products, and we expect to continue to incur significant operating losses for the foreseeable future. As of September 30, 2020, we had $188.2 million in cash and cash equivalents compared to $176.2 million as of December 31, 2019.
In January 2020, we announced the closing of a public offering of 24.5 million shares of common stock at a price of $4.25 per share. We received net proceeds from the offering of $97.7 million after deducting underwriting discounts and offering expenses. In addition, on September 25, 2020, we entered into an Open Market Sale AgreementSM, or Sale Agreement, with Jefferies, LLC, or Jefferies, as sales agent, pursuant to which we may offer and sell, from time to time, through Jefferies, shares of our common stock having an aggregate offering price of up to $100.0 million. Through the date of filing this report, we have sold approximately 12.9 million shares of our common stock under the Sale Agreement, generating net proceeds of approximately $54.0 million after deducting offering commissions and estimated expenses. None of these sales occurred during the three months ended September 30, 2020.
Critical Accounting Policies
We prepare our consolidated financial statements in accordance with accounting principles generally accepted in the U.S. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues, and expenses and related disclosure of contingent assets and liabilities. On an on-going basis, we evaluate our estimates, including those related to our collaborative agreements, clinical trial accruals, and stock-based compensation. We base our estimates on historical experience and various other assumptions that we believe to be reasonable under the circumstances. Actual results may differ from these estimates.
RESULTS OF OPERATIONS
Comparison of Three Months ended September 30, 2020 and 2019
Revenues
Our total revenues for the three months ended September 30, 2020 and 2019 were $18.2 million and $13.3 million, respectively. The $4.9 million increase in revenues in the three months ended September 30, 2020 from the same period in the prior year is primarily attributable to an increase in non-cash royalty revenue, which is discussed further below.
License and Milestone Fees
The amount of license and milestone fees we earn is directly related to the number of our collaborators, the advancement of product candidates covered by the agreements with our collaborators, and the overall success in the clinical trials of these product candidates. As such, the amount of license and milestone fees may vary significantly from quarter to quarter and year to year. License and milestone fee revenue was $0.1 million for each of the three months ended September 30, 2020 and 2019.
Deferred revenue of $130.5 million as of September 30, 2020 includes $60.5 million remaining from an upfront payment related to the license options granted to Jazz in August 2017 and $65.2 million related to the sale of our residual rights to receive royalty payments on commercial sales of Kadcyla, with the remainder of the balance primarily representing consideration received from our collaborators pursuant to our license agreements which we have yet to earn pursuant to our revenue recognition policy.
Non-cash Royalty Revenue Related to the Sale of Future Royalties
Kadcyla is an ADC marketed product resulting from one of our development and commercialization licenses with Roche, through its Genentech unit. We receive royalty reports and payments related to sales of Kadcyla from Roche one quarter in arrears. In accordance with our revenue recognition policy we recorded $18.1 million and $13.2 million of non-cash royalties on net sales of Kadcyla for the three-month periods ended September 30, 2020 and 2019, respectively. The increase in 2020 compared to 2019 is a result of an increase in royalty payments driven by an increase in net sales of Kadcyla, due to market expansion of Kadcyla and approval of Kadcyla for a second indication in 2019. Kadcyla sales occurring after January 1, 2015 are covered by a royalty purchase agreement, whereby the associated cash was initially remitted to IRH, subject to a residual cap. In January 2019, we sold our residual rights to receive royalty payments on