G&A costs include outside professional fees for legal, business development, audit and accounting services. G&A also includes cash and non-cash compensation, travel and other miscellaneous costs of our internal G&A personnel, two in total, who are wholly dedicated to G&A efforts. G&A also includes a proration of our common infrastructure costs for office space and communications. Our G&A expenses also include costs to maintain our intellectual property portfolio. Historically we have expanded our patent prosecution activities and in some cases, we have filed patent applications for non-critical strategic purposes intended to prevent others from filing similar patent claims. We continue to closely monitor our patent applications in the United States, Europe and other countries with the advice of outside legal counsel to determine if they will continue to provide strategic benefits. In cases where we believe the benefit has been realized or it becomes unnecessary due to the issuance of other patents, or for other reasons that will not affect the strength of our intellectual property portfolio, we have and will continue to abandon these patent applications in order to reduce our costs of continued prosecution or maintenance.
Critical Accounting Policies
In Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” of our Annual Report on Form 10-K for the year ended December 31, 2020, which was filed with the SEC on March 2, 2021, which we refer to as the Annual Report, we included a discussion of the most significant accounting policies and estimates used in the preparation of our financial statements. There has been no material change in the policies and estimates used in the preparation of our financial statements since the filing of our Annual Report.
Results of Operations
Comparison of the three months ended September 30, 2021 and 2020
Revenues. For the three months ended September 30, 2021 and 2020, we recorded revenue in the amount of approximately $19,000 related to the amortization of unearned license fees.
R&D Expenses. For the three months ended September 30, 2021, our R&D expenses increased by approximately $5,000, or 1,075%, to $5,700 from $500 for the same period in 2020. The 2021 increase relates to the retesting of Tß4 active pharmaceutical ingredient (API) by our contract manufacturer.
G&A Expenses. For the three months ended September 30, 2021, our G&A expenses increased by approximately $118,000, or 40%, to $418,000 from $299,000 for the same period in 2020. The changes in the G&A expenses are reflected in several areas. Increases in professional services (increase of $21,000), investor related services (increase of $2,000) and stock option expense (increase of $111,000) are partially offset with decreases in insurance (decrease of $10,000) and in personnel related (decrease of $6,000). The large increase is stock option expense relates to the timing of grants in 2021 versus 2020 when they were granted in the second quarter.
Interest Expense. For the three months ended September 30, 2021, interest expense increased by approximately $29,000 which reflects the additional interest accrual related to the 2020 Notes.
Net Loss. Our Statements of Operations reflects a net loss of $430,000 for the quarter ended September 30, 2021, versus a net loss of $333,000 for the quarter ended September 30, 2020. The variance is driven by the timing of the stock option grants as well as the recognition of a gain on the PPP loan which was forgiven in Q3 of 2021.
Comparison of the nine months ended September 30, 2021 and 2020
Revenues. For the nine months ended September 30, 2021, we recorded revenue in the amount of $58,000 versus $58,000 in the 2020 period. Revenue in both periods relates to the recognition of the license fees received from ReGenTree and GtreeBNT.
R&D Expenses. For the nine months ended September 30, 2021, our R&D expenses increased by approximately $2,000 or 50%, to $6,600 from $4,400 for the same period in 2020. The 2021 increase relates to the retesting of Tß4 API by our contract manufacturer.