Merck & Company, Inc. (MRK) shares rose 12.12% to $151.56 on Wednesday after the pharmaceutical company announced successful Phase 3 melanoma clinical trial results. The stock moved up sharply from intraday trading levels near $135.17. The update supported Merck’s oncology business as its collaboration with Moderna delivered an important clinical milestone.

Merck & Co., Inc., MRK

Merck Advances After Melanoma Trial Success

Merck and Moderna announced topline results from the Phase 3 INTerpath-001 study. The trial evaluated intismeran autogene in combination with Merck’s KEYTRUDA immunotherapy in patients with melanoma after surgical resection. The study met its primary endpoint of improving recurrence-free survival.

The combination therapy also met a key secondary endpoint measuring distant metastasis-free survival. The companies said the data showed statistically significant improvements compared with KEYTRUDA monotherapy. They also said the treatment produced clinically meaningful benefits in patients with fully resected stage IIB through IV melanoma.

Participants in the study had not received prior systemic melanoma therapy before enrollment. Melanoma is the most serious form of skin cancer, with the American Cancer Society estimating roughly 100,000 new diagnoses in the United States each year. Recurrence-free survival is an established endpoint in adjuvant melanoma research and has previously supported regulatory approvals in the post-surgery setting, including KEYTRUDA’s own approval as an adjuvant melanoma treatment. Merck and Moderna will continue following the trial and evaluating additional secondary endpoints, including overall survival, which is an important long-term measure of treatment effectiveness.

Combination Therapy Reaches a Major Milestone

Intismeran is a personalized mRNA-based neoantigen immunotherapy co-developed by Merck and Moderna. The therapy is designed to identify unique genetic mutations in each patient’s tumor and stimulate an immune response against cancer cells carrying those mutations.

Merck and Moderna said the Phase 3 results mark a significant step for personalized neoantigen cancer therapies. The study produced the first positive Phase 3 data for an individualized neoantigen immunotherapy and the first successful Phase 3 result for an mRNA-based oncology treatment.

For Moderna, the readout represents the first Phase 3 success for its mRNA technology in cancer, a pipeline area the company has emphasized as revenue from its COVID-19 vaccine has declined.

The companies also said the combination did not reveal unexpected safety concerns during the trial. Its safety profile was consistent with earlier studies of intismeran combined with KEYTRUDA. Merck and Moderna plan to present full results at a future international medical conference.

INTerpath Program Expands Across Multiple Cancer Types

Merck and Moderna have expanded their INTerpath clinical development program across several cancer indications and treatment stages. The program now includes nine Phase 2 and Phase 3 studies examining intismeran with KEYTRUDA, with other cancer therapies, and as a monotherapy.

The partnership is studying the approach in melanoma, bladder carcinoma, renal cell carcinoma, and non-small cell lung cancer. The broader research portfolio also includes a prior Phase 2b melanoma study. Another trial covers pancreatic, gastric, and non-small cell lung cancers in different treatment settings.

Merck’s oncology franchise is anchored by KEYTRUDA, making continued innovation a key focus for the company. KEYTRUDA generated $29.5 billion in sales in 2024, close to half of Merck’s total revenue, and the drug’s key patent protection is set to expire later this decade. The latest data could expand Merck’s melanoma treatment options if the combination regimen later receives regulatory approval. Merck and Moderna said they intend to submit the Phase 3 data to regulatory agencies for review.