Merck has dumped Moderna’s mutant KRAS vaccine mRNA-5671. The action, which comes shortly after Merck closed enrollment in a phase 1 trial, leaves Moderna pondering the next steps for the program.
In 2018, Moderna granted Merck the chance to opt in to the co-development of mRNA-5671 after the completion of human proof-of-concept studies. Yet, while Merck had until after the delivery of phase 2 data to make a decision, it has opted to walk away before wrapping up a first-in-human study in patients with non-small cell lung cancer, colorectal cancer and pancreatic adenocarcinoma.
Merck began the phase 1 trial in 2019 to assess the safety and tolerability of mRNA-5671 and find the recommended dose, both as a monotherapy and in combination with Keytruda. The terms of the 2018 deal saw Merck foot the bill for clinical development while Moderna supplied the product.
Moderna embarked on the KRAS project in the belief that delivering multiple neoantigens in one mRNA molecule offers a better way of treating cancers. As mRNA-5671 is designed to present neoantigens for the four most common KRAS mutations, it could turn the immune system against a range of solid tumors. It remains to be seen whether Moderna sees putting that idea to the test as a good use for its money.
While Merck is walking away from mRNA-5671, the 2018 deal has nonetheless generated a return for the company. Merck invested $125 million in Moderna as part of the deal, adding to a $50 million stake it acquired three years earlier. Late in 2020, Merck divested its stake, resulting in $886 million in income on its balance sheet that was “largely related to Moderna.” The sale came after Moderna’s stock soared.
Merck also still retains a stake in another Moderna cancer vaccine, mRNA-4157. The personalized cancer vaccine, which encodes up to 34 neoantigens, missed the mark in colorectal cancer but fared better in head and neck cancer in a small phase 1 study. A clearer picture of the efficacy of mRNA-4157 is on the horizon, with ClinicalTrials.gov putting the primary completion date of a phase 2 melanoma trial as June.