of increased legal expenses and intellectual property filing primarily attributed to DIAMOND and other technologies currently in development; (vi) a $18,000 increase in laboratory equipment and maintenance, driven entirely by new non-capitalizable equipment purchases not directly attributed to an ALEXIS product candidate.
These increases were offset by a $246,000 decrease in outsourced research and development costs, which primarily included reduced stock compensation expenses of $281,000 attributable to non-employees. The offsetting difference of $35,000 was primarily attributed to increased clinical consulting fees.
These cost increases were primarily incurred to support in-vitro testing and validation of our product candidates.
1.
Augmented our research and development team: As of March 31, 2021 compared to March 31, 2020, our average headcount increased to 16 employees from 5.5 employees allocable to research and development and clinical trials preparation.
2.
ALEXIS-ISO-1 Manufacturing and Experimentation: $470,000 increase in spending during the three months ended March 31, 2021 from manufacturing expanded Gamma Delta T-Cells in the recently completed GMP facilities. In addition, in-vivo experimentation costs in the recently completed vivarium facilities contributed to the increase.
General and administrative expenses. Our general and administrative expenses increased by $1,246,400, or 151.15%, to $2,071,000 for the three months ended March 31, 2021 from $824,600 for the three months ended March 31, 2020.
During the three months ended March 31, 2021, the increase primarily resulted from an increase in stock compensation expenses of $627,500, professional services of $511,500, and wages and salaries of $158,600.
Employee related expenses were impacted by increases to headcount, employee salary rates, and equity grant modifications. As of March 31, 2021 compared to March 31, 2020, the headcount for employees allocated to general and administrative purposes increased to 6.5 employees from 3.5 employees, respectively. In addition, the Chief Executive Officer’s salary increased to an annual rate of $504,000 from $280,000 as of March 31, 2021 and 2020, respectively.
As of March 31, 2021 compared to March 31, 2020, the increase in stock compensation expense was primarily driven by stock option grant modification allocated to general and administrative expense which increased stock compensation expense by $577,500.
The increase in professional services expenses was driven by an increase of $341,800 from accounting and audit fees and an increase of $169,700 of other consulting and corporate development fees incurred during the three months ended March 31, 2021 compared to the same period in the prior year.
Gain on loan extinguishment. Gain on loan extinguishment was $105,800 and $0 for the three months ended March 31, 2021 and 2020, respectively. During the year ended December 31, 2020, we applied for forgiveness of the SBA Loan in accordance with the terms of the CARES Act. On February 16, 2021 the SBA granted forgiveness of the SBA Loan and all applicable interest. On the date of forgiveness, the principal and accrued interest totaled $105,800.
Interest expense. Interest expense was $3,700 and $0 for the three months ended March 31, 2021 and 2020, respectively. The increase is entirely driven by cash paid for interest attributed to the financing arrangement for our Director and Officer Insurance policy. The total amount financed was $540,500 with an annual interest rate of 4.59%, to be paid over a period of nine months. As of March 31, 2021, the remaining payable balance on the financed amount was $227,800.
Net loss. As a result of the cumulative effect of the factors described above, our net loss increased to $3,854,500 during the three months ended March 31, 2021 compared to $1,852,700 during the three months ended March 31, 2020.
Comparison of the Years Ended December 31, 2020 and 2019
The following table sets forth key components of our results of operations for the years ended December 31, 2020 and 2019.