Thank you, Mel. The financial results from our second quarter ended June 30, 2022, show a strong balance sheet with a solid cash balance, commensurate equity and no debt.
Cash and cash equivalents grew from $25 million on March 31, 2021, to $28 million at quarter end 2022, which represents a positive change of 12%. Predictive Oncology's recognized net sales revenue of $0.4 million for the quarter was an increase of 6% from the comparative 3-month period in 2021.
The company's gross profit margin grew from 59% in 2021 -- June 2021 to 64% for the comparable quarter of 2022. Net cash used in operating activities was $6.4 million and $5.5 million for the 6 months ended June 30, 2022 and June 30, 2021, respectively. Primarily because of the increase in operating costs and the launch of our PeDAL commercial strategy.
General and administrative expenses increased from $2.1 million in the quarter ended June 30, 2021, to $2.4 million for the corresponding quarter in 2022. Operating expense -- operations expenses increased from $0.6 million in the quarter ended June 30, 2021, to $49 million in the quarter ended June 30, 2022, primarily due to higher staffing and EBITDA. This was partially offset by the timing of research and development expenses and lower consulting fees.
Quarterly sales and marketing expenses as the company increased by $0.1 million for the quarter ended June 30, 2022, to $0.3 million as compared to the corresponding period in 2021 due to staff-related expenses and the implementation of advertising and marketing initiatives.
I'd like to discuss the goodwill expense in the current quarter. Current marketing conditions -- market conditions, I'm sorry, coupled with Predictive Oncology's lower quantitative valuation of zPREDICTA resulted in $7.2 million of a noncash goodwill impairment. This was required due to GAAP standards related to the price we originally paid for zPREDICTA, Predictive Oncology's quarter ending stock price and our value differential between our cash position and market cap.
While we cannot yet report on the potential contracts we have, predictive Oncology is anticipating stronger business growth in the second half of the year with current and potential customers of its validated 3D tour model for: multiple myeloma, which is an existing model; breast cancer, an existing new model; and pancreatic cancer, also an existing new model as well as the testing of immuno-oncology therapies.
Also, now that we validated our PeDAL platform at a statistically significant 92% drug response accuracy rate, have begun commercialization efforts and are implementing highly targeted marketing initiatives, we expect to begin seeing results of those efforts in the next 2 quarters.
On a final note, we are looking forward to attending the Investor Summit in New York this November.
I will now pass the conversation along to Dr. Bush, who will share about our progress in sales and marketing. Pamela?