Moderna mRNA Melanoma Vaccine Plus Keytruda Shows Phase 3 Benefit
On Wednesday, Aug. 19, 2026, Moderna said its personalized mRNA melanoma vaccine intismeran plus Merck's Keytruda helped patients live longer without cancer returning in a Phase 3 trial.[1] After the announcement, Moderna shares more than doubled, rising over 120% to $140.12, while Merck shares rose about 11%.[1]
The Phase 3 trial enrolled more than 1,100 people with advanced-stage melanoma whose tumors had invaded deeply or reached lymph nodes.[2] All patients had their tumors surgically removed and received standard Keytruda; those additionally given intismeran remained cancer-free longer than those on Keytruda alone.[2] Moderna sequences each patient's tumor, uses artificial intelligence to pick mutations to target, and encodes those targets in synthetic mRNA to create a personalized vaccine.[2] Both companies said they will present detailed results at an upcoming international medical meeting and did not disclose exact relapse-free or overall survival durations.[1]
Intismeran is designed as an individualized mRNA cancer vaccine tailored to each patient's tumor mutations and, if approved, would be the first treatment of its kind.[1] Melanoma is the fifth most commonly diagnosed cancer in the United States, with about 112,000 new cases and an estimated 8,500 deaths projected this year.[2]
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📌 Key Facts
- The Phase 3 trial enrolled more than 1,100 people with advanced-stage melanoma whose tumors had invaded deeply or reached lymph nodes, according to CBS's coverage of the study Phase 3 trial.
- Moderna's melanoma vaccine is personalized by sequencing a patient's tumor, using artificial intelligence to select which mutations to target, and encoding those targets in synthetic mRNA personalized mRNA vaccine.
- CBS describes the mechanism as Merck's Keytruda lifting an “invisibility cloak” from cancer cells while the mRNA vaccine trains the immune system (likened to giving a “scent” to a bloodhound), and reports that patients who received the vaccine plus Keytruda remained cancer-free longer than those on Keytruda alone Keytruda.
- Moderna said on August 19, 2026 that initial study results show patients receiving its personalized vaccine intismeran plus Merck's Keytruda lived longer without cancer returning or metastasizing than those who received Keytruda alone, and the companies said they will present detailed results at an upcoming international medical meeting but did not disclose exact durations intismeran.
- Following the announcement, Moderna's shares more than doubled—rising over 120% to $140.12—while Merck shares rose about 11% on August 19, 2026 Moderna's share price.
- Intismeran is designed as an individualized mRNA cancer vaccine tailored to each patient's tumor mutations and, if approved, would be the first treatment of its kind intismeran.
- Melanoma is the fifth most commonly diagnosed cancer in the United States, with about 112,000 new cases and an estimated 8,500 deaths projected this year melanoma.
📰 Source Timeline (3)
Follow how coverage of this story developed over time
- On Wednesday, August 19, 2026, Moderna said initial study results show melanoma patients receiving its personalized mRNA vaccine intismeran plus Merck's Keytruda lived longer without cancer returning or metastasizing than those who received Keytruda alone.
- The companies did not disclose the exact duration of relapse-free or overall survival, saying they plan to present detailed results at an upcoming international medical meeting.
- Following the announcement, Moderna's share price more than doubled, rising over 120% to $140.12, while Merck shares rose about 11% on August 19, 2026.
- The article reiterates that intismeran is designed as an individualized mRNA cancer vaccine tailored to each patient's tumor mutations and, if approved, would be the first treatment of its kind.
- On Wednesday, August 19, 2026, CBS detailed that the Phase 3 trial enrolled more than 1,100 people with advanced-stage melanoma whose tumors had invaded deeply or reached lymph nodes.
- The article explains that each dose of Moderna's melanoma vaccine is personalized by sequencing a patient's tumor, using artificial intelligence to select which mutations to target, and encoding those targets in synthetic mRNA.
- CBS describes the mechanism of action as a combination of Merck's Keytruda lifting an "invisibility cloak" from cancer cells and the mRNA vaccine training the immune system, likened to giving a "scent" to a bloodhound.
- The report reiterates that all patients in the trial had their tumors surgically removed and received standard Keytruda; those additionally given the mRNA vaccine remained cancer-free longer than those on Keytruda alone.
- CBS notes melanoma is the fifth most commonly diagnosed cancer in the United States, with about 112,000 new cases and an estimated 8,500 deaths projected this year.