Moderna shares surge after mRNA cancer vaccine clears Phase 3 trial

Moderna ↗ 147.98% shares soared as much as 100% on Wednesday after the company and partner Merck ↗ 12.71% announced that their personalized mRNA cancer vaccine met both primary goals in a pivotal late-stage melanoma trial — the first positive Phase 3 result ever reported for an mRNA-based cancer therapy.

The Phase 3 INTerpath-001 trial evaluated intismeran autogene, a personalized mRNA vaccine manufactured from mutations in each patient's tumor, combined with Merck's immunotherapy Keytruda in 1,137 patients with surgically removed stage IIB-IV melanoma. The combination demonstrated statistically significant improvements in both recurrence-free survival and distant metastasis-free survival compared with Keytruda alone.reuters+1

A Historic Readout

"These Phase 3 results represent a crucial moment for cancer research," Moderna CEO Stéphane Bancel said in the companies' joint announcement. "For many years, the idea of creating an mRNA treatment designed specifically for each patient's cancer was aspirational. We are now helping turn that vision into a reality."stocktitan+1

The trial was stopped early at its first interim analysis after the positive results became apparent, and no new safety signals emerged. The companies plan to present detailed data at an upcoming international medical meeting and engage with regulators on filing submissions.ibtimes+1

The results build on Phase 2b data reported in January showing the combination reduced the risk of recurrence or death by 49% and distant metastasis or death by 59% at five years of follow-up. However, specific hazard ratios and overall survival data from the Phase 3 study have not yet been disclosed.ts2+1

Market Reaction and Analyst Response

Moderna's stock approached a doubling at its premarket peak before settling in a wide trading range, while Merck climbed roughly 7–10%. The disparity reflects the companies' vastly different sizes: Moderna entered the day with a market capitalization of approximately $25 billion versus Merck's $333 billion.news.sky+2

William Blair upgraded Moderna from Neutral to Outperform following the announcement. RBC Capital Markets analyst Trung Huynh said the "strength of the underlying data must have been compelling to trigger significance at the interim analysis, meaningfully exceeding investor expectations."seekingalpha+1

Leerink Partners analyst Mani Foroohar had characterized the Phase 3 readout as a "make-or-break event" for Moderna's stock ahead of the results. Barclays analysts have estimated the treatment could generate roughly $3 billion in melanoma revenue by 2035.ibtimes+1

Key Uncertainties Remain

Despite the euphoric reaction, analysts cautioned that critical details are outstanding. Citi analyst Geoffrey Meacham noted that detailed hazard ratios, confidence intervals, stage-specific analyses, and manufacturing data "will determine the readout's clinical and commercial quality."reuters

Merck and Moderna are also studying the vaccine in non-small cell lung cancer, bladder cancer, and renal cell carcinoma. Lale Akoner, global market strategist for eToro, said investors "should keep expectations measured" given that overall survival results remain pending and manufacturing personalized vaccines at scale "could be expensive and complex."nai500+1