Prime Medicine, Inc.

Previous wording

We are advancing ourin vivo programs to cure two of the largest genetic liver diseases, Wilson Disease and AATD. Both programs are currently in late stages of pre-clinical development and are on track for IND and/or Clinical Trial Application filings in the first half of 2026 for Wilson Disease and the middle of 2026 for AATD. We intend to leverage the modularity of our platform to expeditiously and efficiently develop these programs supported by our universal liver lipid nanoparticle along with potential regulatory, clinical and other synergies from our modular technology.

Current wording

We are advancing ourin vivo programs to cure two of the largest genetic liver diseases, Wilson disease and AATD. In June 2026, we received clearance of the CTA for PM577a, an investigational Prime Editor for Wilson disease, in New Zealand, representing the first clinical authorization for one of ourin vivo Prime Editing therapies and enabling the initiation of our global Phase 1/2 clinical trial. In July 2026, the FDA cleared our IND application for PM577a. The IND clearance opens participation in our global Phase 1/2 clinical trial to patients in the United States, where H1069Q is the single most common pathogenic variant causing Wilson disease. Additionally, we are on track for IND application submission and/or CTA filing in the third quarter of 2026 for PM647 in AATD. We intend to leverage the modularity of our platform to expeditiously and efficiently develop these programs supported by our universal liver lipid nanoparticle along with potential regulatory, clinical and other synergies from our modular technology.

Previous wording

We also continue to advance our in vivo Cystic Fibrosis program with support from Cystic Fibrosis Foundation and our efforts to develop Prime Edited CAR-T products for hematology, immunology, and oncology in partnership with BMS. In addition, we will continue to pursue additional business development opportunities to accelerate innovation, ensure the broadest application of Prime Editing, and further bolster our financial resources.

Current wording

We also continue to advance ourin vivo Cystic Fibrosis program with support from Cystic Fibrosis Foundation and our efforts to develop Prime Edited CAR-T products for hematology, immunology, and oncology in partnership with BMS. In addition, we will continue to pursue additional business development opportunities to accelerate innovation, ensure the broadest application of Prime Editing, and further bolster our financial resources.

Previous wording

In August 2025, we announced additional data from the first patient dosed and initial data from the second patient dosed in our Phase 1/2 trial in CGD. We continue to engage in regulatory dialogue with the FDA toward a potential Biologics License Application filing for PM359.

Current wording

In August 2025, we announced additional data from the first patient dosed and initial data from the second patient dosed in our Phase 1/2 trial in CGD. We continue to engage in regulatory dialogue with the FDA toward a Biologics License Application submission for PM359, which is planned for the first half of 2027. In June 2026, the FDA granted RMAT designation for PM359, which provides opportunities for intensive FDA guidance and potential expedited review during the program’s development.

Previous wording

The $6.5 million decrease in research and development expenses for the three months ended March 31, 2026 as compared to the three months ended March 31, 2025 was primarily driven by:

Current wording

The $8.0 million decrease in research and development expenses for the three months ended June 30, 2026 as compared to the three months ended June 30, 2025 was primarily driven by:

Previous wording

These were offset by a $1.2 million increase in clinical expenses as we advance our Wilson Disease and AATD programs.

Current wording

These were offset by a $1.5 million increase in clinical expenses as we advance our Wilson disease and AATD programs.

Previous wording

The $4.1 million increase in general and administrative expenses for the three months ended March 31, 2026 as compared to the three months ended March 31, 2025 was primarily driven by a $5.7 million increase in professional and consultant fees, a majority of which are arbitration-related legal expenses. This was offset by a $1.6 million decrease in personnel expenses driven primarily by fewer G&A personnel resulting from the workforce reduction announced in May 2025.

Current wording

The $2.0 million increase in general and administrative expenses for the six months ended June 30, 2026 as compared to the six months ended June 30, 2025 was primarily driven by a $4.2 million increase in professional and consultant fees, a majority of which are arbitration-related legal expenses. This was offset by a $3.1 million decrease in personnel expenses driven primarily by fewer personnel-related costs resulting from the workforce reduction announced in May 2025 and a decrease in stock compensation expense of $1.4 million.

Previous wording

The change in fair value of related party short-term investment for the three months ended March 31, 2025 was the result of Beam’s stock price movement.

Current wording

The change in fair value of related party short-term investment for the six months ended June 30, 2025 was the result of Beam’s stock price movement.

Previous wording

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we advance the preclinical development of our current research programs, commence the clinical development of any product candidates we may identify, and continue our platform development and early-stage research activities. We have not yet commercialized any products and we do not expect to generate revenue from sales of products for several years, if at all. To date, we have funded our operations primarily with proceeds from sales of preferred stock and from our public offerings and through payments from our collaboration partners. As of March 31, 2026, we had cash, cash equivalents, and investments of $135.5 million, excluding our restricted cash, or $149.2 million, including restricted cash.

Current wording

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we advance the preclinical development of our current research programs, commence the clinical development of any product candidates we may identify, and continue our platform development and early-stage research activities. We have not yet commercialized any products and we do not expect to generate revenue from sales of products for several years, if at all. To date, we have funded our operations primarily with proceeds from sales of preferred stock and from our public offerings and through payments from our collaboration partners. As of June 30, 2026, we had cash, cash equivalents, and investments of $95.1 million, excluding our restricted cash, or $108.8 million, including restricted cash.

Previous wording

In November 2023, we entered into the Sales Agreement with Jefferies under which we may, from time to time, issue and sell shares of our common stock having an aggregate sales proceeds of up to $300.0 million, in a series of one or more at-the-market equity offerings as part of our 2023 ATM Program. Any shares will be sold pursuant to the Registration Statement and the sales agreement prospectus filed therewith, which covers the offer and sale of shares of our common stock under the 2023 ATM Program having an aggregate offering price of up to $200.0 million of the $300.0 million authorized under the Sales Agreement. If we wish to offer and sell additional shares of our common stock under the Sales Agreement in excess of the $200.0 million registered under the Registration Statement, for up to an additional $100.0 million, we must file with the SEC one or more additional prospectus supplements to register under the Securities Act, the offer and sale of any such additional shares of our common stock we wish to offer and sell from time to time under the Sales Agreement. Jefferies is not required to sell any specific share amounts but acts as our sales agent, using commercially reasonable efforts consistent with its normal trading and sales practices. We will pay Jefferies a commission equal to 3.0% of the aggregate gross proceeds we receive from each sale of our shares of common stock. Our common stock will be sold at prevailing market prices at the time of the sale, and as a result, prices may vary. As of March 31, 2026, we have not sold any shares of common stock under the 2023 ATM Program.

Current wording

In November 2023, we entered into the Sales Agreement with Jefferies under which we may, from time to time, issue and sell shares of our common stock having an aggregate sales proceeds of up to $300.0 million, in a series of one or more at-the-market equity offerings as part of our 2023 ATM Program. Any shares will be sold pursuant to the Registration Statement and the sales agreement prospectus filed therewith, which covers the offer and sale of shares of our common stock under the 2023 ATM Program having an aggregate offering price of up to $200.0 million of the $300.0 million authorized under the Sales Agreement. If we wish to offer and sell additional shares of our common stock under the Sales Agreement in excess of the $200.0 million registered under the Registration Statement, for up to an additional $100.0 million, we must file with the SEC one or more additional prospectus supplements to register under the Securities Act, the offer and sale of any such additional shares of our common stock we wish to offer and sell from time to time under the Sales Agreement. Jefferies is not required to sell any specific share amounts but acts as our sales agent, using commercially reasonable efforts consistent with its normal trading and sales practices. We will pay Jefferies a commission equal to 3.0% of the aggregate gross proceeds we receive from each sale of our shares of common stock. Our common stock will be sold at prevailing market prices at the time of the sale, and as a result, prices may vary.

Previous wording

Since our inception, we have incurred substantial losses. As of March 31, 2026, we had an accumulated deficit of $937.5 million and we expect to generate operating losses and negative operating cash flows for the foreseeable future. As stated above, as of March 31, 2026, we maintained cash, cash equivalents, and short-term investments of $135.5 million.

Current wording

Since our inception, we have incurred substantial losses. As of June 30, 2026, we had an accumulated deficit of $979.6 million and we expect to generate operating losses and negative operating cash flows for the foreseeable future. As stated above, as of June 30, 2026, we maintained cash, cash equivalents, and short-term investments of $95.1 million.

Previous wording

In accordance with ASC 205-40, we evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date on which this Quarterly Report on Form 10-Q is filed. Based on the our cash, cash equivalents, and short-term investments as of March 31, 2026, our current and forecasted level of operations and forecasted cash flows, our ability to continue as a going concern is dependent upon our ability to obtain the necessary financing to meet our obligations and repay our liabilities arising from normal business operations when they come due. Management plans to provide for capital requirements through financing or other transactions, and selling shares under our “at the market offering” program. There can be no assurance that we will be able to raise additional capital to fund operations with terms acceptable to us, or at all. Because certain elements of our plans to mitigate the conditions that raised substantial doubt about our ability to continue as a going concern are outside of our control, including the ability to raise capital through an equity or other financing, those elements cannot be considered probable according to ASC 205-40, and therefore cannot be considered in the evaluation of mitigating factors. As a result, we concluded that substantial doubt exists about our ability to continue as a going concern for 12 months from the date these condensed consolidated financial statements are issued.

Current wording

In accordance with ASC 205-40, we evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date on which this Quarterly Report on Form 10-Q is filed. Based on our cash, cash equivalents, and short-term investments as of June 30, 2026, our current and forecasted level of operations and forecasted cash flows, our ability to continue as a going concern is dependent upon our ability to obtain the necessary financing to meet our obligations and repay our liabilities arising from normal business operations when they come due. Management plans to provide for capital requirements through financing or other transactions, and selling shares under our “at the market offering” program. There can be no assurance that we will be able to raise additional capital to fund operations with terms acceptable to us, or at all. Because certain elements of our plans to mitigate the conditions that raised substantial doubt about our ability to continue as a going concern are outside of our control, including the ability to raise capital through an equity or other financing, those elements cannot be considered probable according to ASC 205-40, and therefore cannot be considered in the evaluation of mitigating factors. As a result, we concluded that substantial doubt exists about our ability to continue as a going concern for 12 months from the date these condensed consolidated financial statements are issued.

Previous wording

The condensed consolidated financial statements as of March 31, 2026 have been prepared under the assumption that we will continue as a going concern for the next 12 months and that contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. Our ability to continue as a going concern is dependent upon our uncertain ability to obtain additional capital, reduce expenditures and/or execute on its business plan. These condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Current wording

The condensed consolidated financial statements as of June 30, 2026 have been prepared under the assumption that we will continue as a going concern for the next 12 months and that contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. Our ability to continue as a going concern is dependent upon our uncertain ability to obtain additional capital, reduce expenditures and/or execute on our business plan. These condensed consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Previous wording

Net cash used in operating activities for the three months ended March 31, 2026 was driven primarily by the following uses of cash:

Current wording

Net cash used in operating activities for the six months ended June 30, 2026 was driven primarily by the following uses of cash:

Previous wording

•$1.9 million change in lease liabilities.

Current wording

•$3.9 million change in lease liabilities;

Previous wording

•$6.7 million change in accrued expenses and other current liabilities; and

Current wording

•$3.6 million change in accrued expenses and other current liabilities;

Previous wording

•$3.6 million change in accounts payable; and

Current wording

•$3.0 million change in accounts payable; and

Previous wording

•$1.4 million change in deferred revenue from consideration received from BMS in September 2024.

Current wording

•$2.0 million change in deferred revenue — related party.

Previous wording

•$8.9 million of non-cash amounts included in net loss, which primarily consisted of stock-based compensation expense, non-cash lease expense, and depreciation expense;

Current wording

•$18.1 million of non-cash amounts included in net loss, which primarily consisted of stock-based compensation expense, non-cash lease expense, and depreciation expense; and

Previous wording

•$1.2 million change in prepaid expenses and other current assets.

Current wording

•$1.9 million change in prepaid expenses and other current assets.

Previous wording

Net cash used in operating activities for the three months ended March 31, 2025 was driven primarily by the following uses of cash:

Current wording

Net cash used in operating activities for the six months ended June 30, 2025 was driven primarily by the following uses of cash:

Previous wording

•$4.5 million change in accrued expenses and other current liabilities; and

Current wording

•$1.7 million change in accrued expenses and other current liabilities; and

Previous wording

•$1.9 million change in accounts payable.

Current wording

•$1.5 million change in accounts payable.

Previous wording

•$10.7 million of non-cash amounts included in net loss, which primarily consisted of stock-based compensation expense, non-cash lease expense, depreciation and amortization expense, and change in fair value of short-term investment — related party; and

Current wording

These were offset by $21.3 million of non-cash amounts included in net loss, which primarily consisted of stock-based compensation expense, non-cash lease expense, depreciation expense, and change in fair value of short-term investment — related party.

Previous wording

Net cash provided by investing activities for the three months ended March 31, 2026 was driven primarily by $43.6 million of maturities of marketable securities, net of purchases.

Current wording

Net cash provided by investing activities for the six months ended June 30, 2026 was driven primarily by $67.7 million of maturities of investments, net of purchases.

Previous wording

Net cash used in investing activities for the three months ended March 31, 2025 was driven primarily by the following:

Current wording

Net cash used in investing activities for the six months ended June 30, 2025 was driven primarily by the following:

Previous wording

•$45.3 million of purchases of marketable securities, net of maturities; and

Current wording

•$41.0 million of purchases of investments, net of maturities; and

Previous wording

•$2.4 million of purchases of property and equipment.

Current wording

•$4.0 million of purchases of property and equipment.

Previous wording

Net cash provided by financing activities for the three months ended March 31, 2025 was driven by $6.0 million of proceeds received under our agreement with Cystic Fibrosis Foundation.

Current wording

Net cash provided by financing activities for the six months ended June 30, 2025 was driven by $6.0 million of proceeds received under our agreement with Cystic Fibrosis Foundation.

Previous wording

During the three months ended March 31, 2026, except for the minimum lease commitments disclosed in Note 6, Leases, to the unaudited condensed consolidated financial statements in this Quarterly Report on Form 10-Q, there were no significant changes to our contractual obligations and commitments described under Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2025.

Current wording

During the six months ended June 30, 2026, except for the minimum lease commitments disclosed in Note 6, Leases, to the unaudited condensed consolidated financial statements in this Quarterly Report on Form 10-Q, there were no significant changes to our contractual obligations and commitments described under Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2025.

Previous wording

During the three months ended March 31, 2026, there were no material changes to our critical accounting policies and significant judgments described under Management’s Discussion and Analysis of Critical Accounting Policies and Significant Judgments and Estimates which are included in our Annual Report on Form 10-K for the year ended December 31, 2025.

Current wording

During the six months ended June 30, 2026, there were no material changes to our critical accounting policies and significant judgments described under Management’s Discussion and Analysis of Critical Accounting Policies and Significant Judgments and Estimates which are included in our Annual Report on Form 10-K for the year ended December 31, 2025.