Company: PRME
Filing Date: 2025-11-07
Form Type: S-3ASR
Source: 0001628280-25-050428
Chunk: 56

Company: Prime Medicine, Inc.
Filing Date: 2025-11-07
Form: S-3ASR
Chunk 56
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 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.

We also continue to advance our in vivo Cystic Fibrosis program with support from the Cystic Fibrosis Foundation, and our efforts to develop Prime Edited CAR-T products for hematology, immunology and oncology in partnership with Bristol-Myers Squibb Company. 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.

In August 2025, we announced additional data from the first patient dosed and initial data from the second patient dosed in our ongoing Phase 1/2 clinical trial of PM359 in chronic granulomatous disease, or CGD. In the first patient dosed, a single dose of PM359, our candidate for the treatment of CGD, led to 58% dihydrorhodamine positivity by Day 15, 66% by Day 30 and 71% by Day 60, exceeding levels of dihydrohomadine positivity believed to be potentially curative. In the second patient dosed in the trial, a single dose of PM359 led to a 70% dihydrorhodamine positivity by day 15 and 80% by day 30. In both patients, we also observed successful manufacturing from a single mobilization, no serious adverse events related to PM359 and rapid neutrophil and platelet engraftment when compared to other commercially available autologous genetic therapy benchmarks. Based on the data from the two patients, we continue to believe PM359 has the potential to transform the care of p47phox CGD. We plan to have regulatory interactions with the U.S. Food and Drug Administration, or the FDA, based on the current data set.

#### Corporate History
We were incorporated under the laws of the State of Delaware in September 2019 under the name Prime Medicine, Inc. Our principal executive offices are located at 60 First Street, Cambridge, MA 02142 and our telephone number at that address is (617) 465-0013. We maintain an Internet website at the following address: www.primemedicine.com . The information contained in, or that can be accessed through, our website does not constitute a part of this prospectus and is not incorporated by reference in this prospectus or in any other filings we make with the SEC.