Net Cash Used in Operating Activities
The use of cash in all periods resulted primarily from our net losses adjusted for non-cash charges and changes in components of working capital.
Net cash used in operating activities was approximately $49.5 million for the three months ended March 31, 2021, which primarily consisted of operating expenses that relate to our on-going preclinical and clinical activities, patent costs and license fees, and increased costs as a result of staffing needs due to our expanding operations. These expenses were partially offset by cash inflows from license fees received in the period.
Net cash used in operating activities was approximately $54.1 million for the three months ended March 31, 2020, which primarily consisted of operating expenses that relate to our on-going preclinical and clinical activities, patent costs and license fees, and increased costs as a result of staffing needs due to our expanding operations. These expenses were partially offset by unrealized gains associated with our corporate equity securities.
Net Cash Used in Investing Activities
Net cash provided by investing activities was approximately $3.2 million for the three months ended March 31, 2021, primarily related to proceeds from maturities of marketable securities of $130.8 million partially offset by costs used to acquire marketable securities of $127.4 million.
Net cash provided by investing activities was approximately $46.5 million for the three months ended March 31, 2020, primarily related to proceeds from maturities of marketable securities of $115.0 million, partially offset by costs to acquire marketable securities of $66.4 million and costs to acquire property and equipment of $2.2 million.
Net Cash Provided by Financing Activities
Net cash provided by financing activities was approximately $261.5 million for the three months ended March 31, 2021 and consisted of $249.5 million in net proceeds received from the offering of our common stock and $12.0 million in proceeds received from exercises of options for our common stock.
Net cash provided by financing activities was approximately $3.0 million for the three months ended March 31, 2020 and consisted of $3.0 million in proceeds received from exercises of options for our common stock.
Funding Requirements
We expect our expenses to increase in connection with our ongoing activities, particularly as we progress the clinical development of EDIT-101 and EDIT-301; further advance our current research programs and our preclinical development activities; seek to identify product candidates and additional research programs; initiate preclinical testing and clinical trials for other product candidates we identify and develop; maintain, expand, and protect our intellectual property portfolio, including reimbursing our licensors for expenses related to the intellectual property that we in-license from such licensors; hire additional clinical, quality control, and scientific personnel; and incur costs associated with operating as a public company. In addition, if we obtain marketing approval for any product candidate that we identify and develop, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing, and distribution to the extent that such sales, marketing, and distribution are not the responsibility of a collaborator. We do not expect to generate significant recurring revenue unless and until we obtain regulatory approval for and commercialize a product candidate. Furthermore, since 2016 we have incurred, and in future years we expect to continue to incur, significant costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, reduce, or eliminate our research and development programs or future commercialization efforts.