Prime Medicine, Inc. (PRME) published the results of its Phase 1/2 study of PM359 in the New England Journal of Medicine on December 7, 2025. The paper, titled “Prime Editing for p47‑phox Chronic Granulomatous Disease,” reports that two patients treated with the autologous hematopoietic stem cell product achieved rapid neutrophil and platelet engraftment, durable restoration of NADPH oxidase activity, and early clinical benefit, all without safety concerns.
The study’s key metrics underscore the platform’s precision: by Day 30, patients reached 69 % and 83 % DHR⁺ neutrophils, surpassing the 20 % clinical threshold for functional recovery. Toxicities were limited to those expected from busulfan‑based conditioning, and no off‑target edits or insertional mutagenesis were detected. The data also show high recovery of viable corrected cells after a single mobilization cycle, indicating that the therapy can be manufactured and delivered at clinical scale.
These results validate Prime Medicine’s Prime Editing technology, which avoids double‑strand breaks and is therefore expected to be better tolerated in hematopoietic stem cells. The success of PM359 positions the company to expand the platform to other genetic diseases and strengthens its competitive stance against CRISPR‑based and viral vector approaches. Prime Medicine’s diversified pipeline—spanning liver, lung, and immunology/oncology—benefits from this proof of concept, as the company can now demonstrate that its editing platform works in a complex, clinically relevant setting.
Chief Medical Officer Mohammed Asmal said, “Publication of these first‑human data highlights Prime Editing’s promise as a next‑generation therapeutic platform, capable of delivering meaningful benefits to patients and scalable manufacturing.” He added that the safety profile and lack of double‑strand breaks suggest a lower risk of insertional mutagenesis compared with other gene‑editing modalities, reinforcing the company’s long‑term vision for one‑time curative therapies.
On December 8, 2025, PRME’s shares rose 10.29 % to close at $4.13, reflecting investor enthusiasm for the data. Analysts noted that the positive safety and efficacy profile, combined with the platform’s scalability, were key drivers of the market reaction, and the stock’s performance underscored confidence in Prime Medicine’s ability to translate its technology into a broader therapeutic portfolio.
Prime Medicine’s achievement is particularly significant given the rarity of p47‑phox CGD, a disease that currently relies on lifelong antibiotics and high‑risk bone‑marrow transplantation. The orphan drug designation and FDA rare pediatric status give the company a regulatory advantage, while the NEJM publication provides a high‑impact validation that can accelerate future clinical development and potential reimbursement discussions. The data also set a benchmark for the gene‑editing field, suggesting that Prime Editing can achieve durable, safe corrections in human patients without the genomic scars associated with older technologies.
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