A New Personalized Cancer Vaccine Could Keep Skin Cancer From Coming Back, Drugmakers Say

A personalized cancer vaccine, used in combination with an existing treatment, helped prevent the return and spread of melanoma in a late-stage clinical trial, Moderna and Merck, the companies developing the drug, announced this week. The results bring the vaccine, called intismeran, one step closer to regulatory approval and potentially wider use. Intismeran is a personalized cancer vaccine, also known as an individualized neoantigen therapy.

The vaccine isn’t designed to stop cancer from occurring in the first place. Rather, it aims to keep the disease from returning in patients who have already had it. It relies on the same mRNA, or messenger RNA, technology as many Covid-19 vaccines and a new mRNA flu shot.

While those vaccines target viruses, intismeran uses a similar approach to fight cancer. MFlusiva, an mRNA flu vaccine developed by Moderna, will be available for this year's flu season for people ages 50 and up. For this trial, a version of intismeran was created exclusively for each patient, a process that took about six weeks.

Researchers made each personalized treatment by sampling the patient’s cancer tumor, then genetically sequencing the cells to identify unique mutations. Because of these mutations, tumor cells produce proteins called neoantigens, which sit on the cells’ surface. Once injected, the personalized vaccine helps train the immune system to recognize and attack cancer cells that carry these neoantigens.

Researchers recruited 1,137 patients whose advanced melanoma had been surgically removed but was considered likely to return. All participants received pembrolizumab, an immunotherapy cancer treatment drug also made by Moderna and Merck and sold under the brand name Keytruda. In addition to pembrolizumab, about half of the patients were also given intismeran; the other half were given a placebo.

Neither the participants nor their doctors knew who received the cancer vaccine. According to Merck and Moderna, participants who were given both intismeran and pembrolizumab lived longer without their cancer coming back than those who only took pembrolizumab. Similarly, patients who took both intismeran and pembrolizumab went longer without developing new lesions outside the original site of the cancer.