Moderna cancer vaccine with Merck’s Keytruda delays melanoma recurrence

Results revealed at a medical meeting suggest that adding a personalized cancer vaccine based on mRNA technology to Keytruda, which boosts the immune response, could extend the time patients have without relapse or death, said Dr. Jeffrey Weber of NYU Langone Perlmutter Cancer Center, which presented the results.

“From the point of view of general cancer therapy, this is a potentially major breakthrough,” said Dr. Ryan Sullivan, a melanoma expert at Mass General Cancer who worked on the study.

The results, presented at the meeting of the American Association for Cancer Research in Orlando, Florida, add data details to the partial findings released by the companies in December.

The Merck/Moderna collaboration is one of several combining powerful drugs that unleash the immune system to target cancers with mRNA vaccine technology. BioNTech SE and Gritstone Bio Inc are working on competing cancer vaccines based on mRNA technology.

Moderna’s vaccine is custom-built based on an analysis of a patient’s tumors after surgical removal. Vaccines are designed to train the immune system to recognize and attack specific mutations in cancer cells.

Merck’s Keytruda, which is approved to treat melanoma and many other cancers, belongs to a class of widely used immunotherapies known as checkpoint inhibitors, designed to disable the PD-1 protein, or death 1, which helps cancer evade the immune system.

In the midstage study, men and women at high risk of recurrence of their melanoma were enrolled.

Among the 107 study subjects who received both the experimental vaccine, mRNA-4157/V940, and Keytruda, cancer returned in 24 subjects (22.4%) within two years of follow-up, compared with 20 of 50 ( 40%) who received only Keytruda.

There was little difference between response rates among people whose tumors had many mutations — a typical predictor of response to immunotherapy — and those whose tumors did not.

Severe side effects were similar between the two arms of the study, the scientists reported. Fatigue was the most common side effect reported by patients specifically associated with the vaccine.

Merck said the companies are in discussions with US regulators about designing an advanced-stage study that is likely to be needed to approve the combination regimen.

It could take three or four years before the results of larger studies are known, Eliav Barr, Merck’s head of global clinical development and chief medical officer, said in an interview.

Barr said it took Moderna about eight weeks to design a personalized mRNA vaccine for each patient.

Similar experimental cancer vaccines targeting a single tumor mutation or neoantigen have been developed in the past.

Moderna’s mRNA technology allowed the inclusion of up to 34 neoantigens, which Barr called “amazing.”

Currently, scientists cannot predict which single mutation is important in generating an antitumor response. By using mRNA technology in combination with Keytruda, “we can create this shotgun approach … that can create a stronger immune response,” Barr said.