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Moderna–Merck Melanoma Vaccine Leak: What the Phase 3 Data Showed
Moderna and Merck confirmed that intismeran autogene plus Keytruda cut the risk of melanoma recurrence or death by 42% versus Keytruda alone; overall survival data are not yet mature. The results appeared on Oncology Central around 12:30 p.m.
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Key takeaways
- Moderna and Merck confirmed that intismeran autogene plus Keytruda cut the risk of melanoma recurrence or death by 42% versus Keytruda alone; overall survival data are not yet mature.
- The results appeared on Oncology Central around 12:30 p.m. ET on October 22, 2026, and were removed shortly afterward, two days before the planned conference presentation.
- Moderna’s shares fell as much as 25% despite the positive trial: Reuters described the reaction as “sell the news” after a months long rally.
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openai.comCreate a landscape editorial hero image for this Studio Global article: How did the premature online disclosure of Moderna and Merck’s personalized melanoma vaccine intismeran autogene results unfold—including th. Article summary: The disclosure prompted a sharp “sell-the-news” reaction, not evidence that the trial had failed: Moderna and Merck subsequently confirmed a statistically significant 42% reduction in recurrence or death with intismeran . Topic tags: general, news, general web. Style: premium digital editorial illustration, source-backed research mood, clean composition, high detail, modern web publication hero. Use reference image context only for broad subject, composition, and topical grounding; do not copy the exact image. Avoid: logos, brand marks, copyrighted characters, real person likenesses, fake screenshots, UI text, readable text, watermarks, charts with fake numbers
Moderna and Merck’s Phase 3 melanoma-vaccine results surfaced online before their planned conference presentation, then were confirmed by the companies later that day. The trial showed a statistically significant benefit from adding intismeran autogene to Keytruda—but the disclosure was followed by a sharp drop in Moderna’s shares, a reminder that investor expectations and clinical results are different measures of success. 4
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How the results appeared early
On Thursday, October 22, 2026, results appeared on the medical news site Oncology Central at about 12:30 p.m. ET and were taken down shortly afterward. They had been scheduled for presentation at the European Society for Medical Oncology (ESMO) Congress on Saturday. 5
Bloomberg reporting said details also circulated through unverified accounts on X. The available reports do not establish who first posted the results or how the early disclosure happened. 23
Later on Thursday, Moderna and Merck announced detailed positive results from INTerpath-001 and said the findings would be presented at the ESMO Presidential Symposium. 4
What INTerpath-001 found
The Phase 3 trial tested intismeran autogene, an investigational individualized mRNA neoantigen therapy, plus pembrolizumab (Keytruda) against Keytruda alone after surgery for stage IIB–IV melanoma. A trial summary reported that 1,137 patients were enrolled. 4
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At a prespecified analysis after a median follow-up of 24.6 months, the combination reduced the risk of recurrence or death by 42% compared with Keytruda alone. The hazard ratio was 0.58 (95% confidence interval, 0.45–0.75; p<0.001). The combination also reduced the risk of distant metastasis or death by 38%. 4
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The trial met its primary recurrence-free survival endpoint and its key secondary distant-metastasis-free survival endpoint. Overall-survival data were not yet mature, so the results do not establish a definitive overall-survival benefit. 30
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Why positive results coincided with a stock drop
Moderna shares fell as much as 25% on the day the results surfaced; Merck shares also declined. 5 Reuters characterized Moderna’s move as a “sell-the-news” reaction after a months-long rally, when investors had already bid up expectations around the study.
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The reported benefit also landed close to analyst expectations, while leaving questions about whether the approach would work in cancers beyond melanoma. 2 That helps explain how the trial could meet its endpoints and still disappoint some investors: the market was reacting not just to whether the results were positive, but to how they compared with expectations already reflected in the share price.
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How to read the Phase 2 and Phase 3 percentages
Some coverage compared Phase 3’s 42% reduction with a reported 49% reduction in recurrence or death in the earlier Phase 2 study. 44 The difference between those figures does not, by itself, show that the treatment became less effective: they are estimates from separate trials, not a direct randomized comparison between the two results.
The Phase 3 finding is important on its own because it showed a recurrence-free and distant-metastasis-free survival benefit for the combination in a larger, late-stage trial. Reuters described the result as a potential step toward more personalized cancer treatment. 1
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What happens next—and what remains unknown
The companies said the detailed INTerpath-001 results would be presented at the ESMO Presidential Symposium. Moderna’s published schedule listed the session for October 24, 2026, at 10:30 a.m. EDT, with Georgina V. Long as presenter. 4
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The key clinical caveat remains overall survival: those data were not mature at the reported analysis. The trial results support a benefit in the studied melanoma setting, but do not yet answer whether the combination improves overall survival or whether the approach will benefit patients with other cancer types. 2
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What is the short answer to "Moderna–Merck Melanoma Vaccine Leak: What the Phase 3 Data Showed"?
Moderna and Merck confirmed that intismeran autogene plus Keytruda cut the risk of melanoma recurrence or death by 42% versus Keytruda alone; overall survival data are not yet mature.
What are the key points to validate first?
Moderna and Merck confirmed that intismeran autogene plus Keytruda cut the risk of melanoma recurrence or death by 42% versus Keytruda alone; overall survival data are not yet mature. The results appeared on Oncology Central around 12:30 p.m. ET on October 22, 2026, and were removed shortly afterward, two days before the planned conference presentation.
What should I do next in practice?
Moderna’s shares fell as much as 25% despite the positive trial: Reuters described the reaction as “sell the news” after a months long rally.
Sources
merck.comMerck and Moderna Will Present Results From Landmark Phase 3 INTerpath-001 Trial for Intismeran Autogene Plus KEYTRUDA® (pembrolizumab) at ESMO 2026 Presidential Symposium - Merck.com
investing.comModerna shares plunge on apparent cancer vaccine data ...
reuters.comModerna sheds about $24 billion as cancer vaccine data triggers 'sell-the-news' retreat