Merck and Moderna Report First Positive Phase 3 Individualized mRNA Cancer Trial

In August 2026, Merck & Co., Inc. (MRK) and Moderna, Inc. reported that their Phase 3 INTerpath-001 trial met its primary and key secondary endpoints. The trial tested individualized mRNA therapy intismeran autogene combined with KEYTRUDA in patients with completely resected stage IIB–IV melanoma.

According to the companies, the combination improved recurrence-free and distant metastasis-free survival versus KEYTRUDA alone, with no new safety issues identified. They described the result as the first positive Phase 3 outcome for both an individualized neoantigen therapy and an mRNA-based cancer therapy, potentially opening a new treatment class across multiple tumor types within the broader INTerpath program.

The readout adds to recent company updates, including Merck's raised 2026 sales guidance of US$66.3 billion to US$67.3 billion, which reflects expected growth from multiple new products before factoring in this melanoma result. A central issue for investors remains Merck's concentration in KEYTRUDA and whether new launches can offset its eventual loss of exclusivity.

Some of the more cautious analysts had assumed only about 3% annual revenue growth to roughly US$71.9 billion by 2029, with earnings of US$22.0 billion. A positive Phase 3 result of this kind is among the developments that could challenge those more conservative assumptions.