Merck dropped it. That is the short version of what happened to mRNA-5671, a Moderna cancer vaccine candidate also coded V941, and it is worth setting beside the hopeful way the project is often described.
The idea behind it was a fair one. KRAS is one of cancer’s most stubborn targets, and in May 2018 Merck agreed to put $125 million into Moderna and to start human tests of a vaccine aimed at tumours carrying mutant versions of the protein. C&EN described the pair’s hope as getting the immune system to go after those tumours.
What the vaccine was built to do
mRNA-5671 is a tetravalent vaccine, meaning it carries instructions for four targets at once: the KRAS mutations G12D, G12V, G13D and G12C. It is given by intramuscular injection. The cancers in view were non-small cell lung cancer, colorectal cancer and pancreatic adenocarcinoma, all with confirmed KRAS driver mutations.
The study itself, listed as NCT03948763 and run by Merck, was a phase 1, open-label trial. Its job was modest: check safety and tolerability, and settle on a preliminary dose for phase 2. Some participants would receive the vaccine alone, others together with the immunotherapy drug pembrolizumab. Enrolment was limited to people with advanced or metastatic disease who had already received, or could not take, every treatment known to help. Participants also had to carry particular immune-system types, HLA-A11:01 and/or HLA C08:02. For patients with these cancers, the entry bar was high.
Sites included centres in the United States, Australia, Hong Kong, South Korea, New Zealand, Singapore and Taiwan.
Merck steps away
On February 24, 2022, Fierce Biotech reported that Merck had dumped the vaccine, shortly after closing enrolment in the phase 1 trial, and that Moderna was left to consider its next steps. AdisInsight lists the trial as terminated “due to business reasons”, with the program marked discontinued in phase 1. Nothing in the record points to a safety finding or to results, good or bad.
The trial registry shows the study ended on August 25, 2022. As of May 2024, no further progress on the vaccine had been announced.
Sources
- mRNA 5671 – AdisInsight
- V941 and Pembrolizumab in Neoplasms and Carcinoma, Non-Small-Cell Lung and Colorectal Neoplasms – Clinical Trials Registry – ICH GCP
- Merck partners with Moderna to test KRas cancer vaccines in humans
- Merck cuts ties to Moderna's early-phase KRAS vaccine, leaving mRNA specialist to mull next steps (Fierce Biotech, search-engine excerpt only; page itself blocked)
