clinical trial expense for the six months ended June 30, 2021 compared to the same period in 2020 was partially offset by an increase of $0.5 million in clinical personnel related costs, including non-cash compensation costs related to share-based compensation expense. The increase in clinical personnel cost is related to increased share-based compensation expense due to new grants to clinical employees in 2021 at higher black-scholes valuations resulting from the increase in the Company’s stock price compared to prior periods.
General and Administrative Expenses
General and administrative expenses were relatively stable and decreased by $62 thousand, or 2.1%, for the three months ended June 30, 2021 compared to the three months ended June 30, 2020. Similarly, general and administrative expenses were relatively stable and decreased by $8 thousand, or 0.1%, for the six months ended June 30, 2021 compared to the six months ended June 30, 2020.
Commercial Expenses
Commercial expenses increased by $0.3 million, or 20.7%, for the three months ended June 31, 2021 compared the same period in 2020. During the second quarter of 2020, we reduced commercial costs in order to focus our efforts on an optimized clinical development pathway for etripamil after we issued topline results of the first part of the NODE-301 in March 2020. During the three months ended June 30, 2021, we increased our investment in commercialization activities resulting in higher expenses when compared to the period in 2020.
Commercial expenses decreased by $0.5 million, or 13.5%, for the six months ended June 31, 2020, compared the same period in 2020. This decrease is mostly due to the fact that spending before we issued topline results of the first part of the NODE-301 in March 2020 was significantly higher compared to the same period in 2021.
Interest Income, Net
Interest income, net of bank charges, was $0.1 million for both the three-month periods ended June 30, 2021 and 2020. Interest income, net of bank charges, was $0.1 million and $0.5 million for the six-month periods ended June 30, 2021 and 2020, respectively. The reduction in interest income was due to lower interest rates earned on investments in 2021 when compared to 2020.
Net Income (Loss)
We had net income of $0.8 million and a net loss of $13.0 million for the three months ended June 30, 2021 and 2020, respectively. We had net losses of $11.7 and $29.3 million for the six months ended June 30, 2021 and 2020, respectively. The net income in the second quarter of 2021 and the decrease in net loss for the for the six months ended June 30, 2021 compared to the six months ended June 30, 2020 is due to the upfront payment received from the License Agreement, which was recognized as collaboration revenue.
Liquidity and Capital Resources
Sources of Liquidity
Except for the three months ended June 30, 2021, we have incurred operating losses and experienced negative operating cash flows since our inception, and we anticipate continuing to incur losses for at least the next several years. As of June 30, 2021, we had cash, cash equivalents and short-term investments of $135.8 million and an accumulated deficit of $176.0 million.
Pursuant to the License agreement, we received an upfront cash payment of $15 million (see note 3 of our unaudited interim condensed consolidated financial statement) during the three months ended June 30, 2021, and in the future could receive up to $107.5 million in total development and sales milestone payments. In addition, under the License Agreement, we will receive tiered royalty payments ranging from a percentage in the low double digits to the high double digits of Net Sales (as defined in the License Agreement) of all products sold in the Territory.