Viral Post Distorts Cancer Vaccine Trial Data

The post in question was published on X on August 19, 2026, by William Makis, quoting a separate post from The Kobeissi Letter announcing that Moderna stock had surged more than 110% after the company reported the first positive Phase 3 results for a personalized cancer vaccine. Makis's commentary frames the same vaccine as ineffective, but the underlying clinical evidence tells a different story.

The efficacy claim is contradicted by peer-reviewed and company-reported data. The Lancet publication of the Phase 2b KEYNOTE-942 study reported that adding mRNA-4157 to pembrolizumab prolonged recurrence-free survival versus pembrolizumab alone in patients with resected high-risk melanoma, with an 18-month recurrence-free survival of 79% versus 62% and a hazard ratio of 0.561 for recurrence or death. A January 2026 Merck press release confirmed that at a median five-year follow-up, the combination reduced the risk of recurrence or death by 49% (HR=0.510) compared with Keytruda alone. STAT News reported on August 19, 2026 that Merck and Moderna announced the vaccine "slowed the return of melanoma and its spread to other parts of the body" in a late-stage trial — described as the first randomized Phase 3 study aimed at definitively proving benefit for a neoantigen vaccine. None of these sources describe the benefit as "minimal."

The post's specific numbers are a mix of accurate protocol details and a distorted safety figure. The Lancet paper confirms that mRNA-4157 was administered at a maximum of nine doses and pembrolizumab at a maximum of 18 doses, matching the "27 injections (18 Keytruda, 9 mRNA)" claim. However, the "36% Grade 3+ side effects" figure is not what the trial reported. Grade 3 or higher treatment-related adverse events occurred in 25% of patients receiving the combination, not 36%. The 36% figure corresponds to immune-mediated adverse events of any grade, which is a broader and less severe category. Conflating the two inflates the apparent toxicity of the regimen.

The remaining claims — a $500,000 estimated cost and the assertion that ivermectin, mebendazole, and fenbendazole outperform the vaccine at a fraction of the price — are unsupported by the provided sources. No clinical trial data in the materials shows these antiparasitic drugs producing superior recurrence-free or overall survival outcomes in melanoma, and no source confirms the specific $500,000 price tag. The post also does not engage with the Phase 3 announcement it is quoting, which directly undercuts its central thesis. Readers should treat the post's characterization of the vaccine as ineffective as inconsistent with the published trial evidence.