A personalized cancer vaccine, used alongside pembrolizumab, helped delay the return and spread of melanoma in a late-stage clinical trial, the drugmakers announced this week. The findings move the investigational shot, intismeran, closer to possible regulatory review and broader use.
Moderna chief executive Stéphane Bancel called the results “a new chapter in cancer care,” in televised remarks.
How the personalized cancer vaccine works
Intismeran is an individualized neoantigen therapy that does not prevent cancer from occurring. Instead, it is designed to reduce the risk of the disease returning in patients who have already been treated.
The approach uses mRNA technology similar to that used in Covid-19 vaccines and a new mRNA flu shot, but it targets cancer rather than viruses.
For the study, a bespoke version of intismeran was produced for each participant over roughly six weeks. Researchers sampled each patient’s tumor, then sequenced it to pinpoint unique mutations.
These mutations lead tumor cells to display proteins known as neoantigens on their surface. The personalized vaccine is intended to train the immune system to recognize and attack cells carrying those neoantigens.
Trial design and topline results
The trial enrolled 1,137 people whose advanced melanoma had been surgically removed but remained at high risk of recurrence. All participants received pembrolizumab, an immunotherapy marketed as Keytruda.
About half also received intismeran, while the remainder received a placebo. The study was blinded to patients and physicians.
According to the companies, those treated with both intismeran and pembrolizumab went longer without their cancer returning compared with those who received pembrolizumab alone. They also experienced longer periods without new lesions developing outside the original tumor site.
The firms did not release detailed data, describing the outcomes as clinically meaningful. They plan to present the full results at an upcoming international medical meeting and submit them to regulators.
Context from earlier studies
Earlier this year, the partners reported midstage data indicating that combining intismeran with pembrolizumab reduced the risk of melanoma recurrence or spread by 49 percent over five years versus pembrolizumab alone.
Melanoma burden and expert reaction
Melanoma is the deadliest skin cancer, accounting for an estimated 8,510 deaths annually in the United States. When detected early it is often treatable, but advanced disease can be challenging because it may spread deeper in the skin or to other organs.
Outside specialists are awaiting the full dataset, though they say the topline findings appear encouraging and consistent with recent smaller studies. Jedd Wolchok, director of the Meyer Cancer Center at Weill Cornell Medicine, who was not involved in the trial, said the results suggest that a personalized vaccine built from tumor sequencing could delay melanoma progression and mark a new addition to standard therapy.
Potential beyond melanoma and personalized cancer vaccine implications
While the study focused on melanoma, experts say the same strategy could extend to other cancers and some rare conditions linked to genetic mutations. Personalized mRNA vaccines are also in development for pancreatic, stomach, kidney, bladder, colon, and lung cancers.
Robert Vonderheide, director of Penn Medicine’s Abramson Cancer Center and president-elect of the American Association for Cancer Research, said multiple trial readouts are expected in the coming years and that this week’s news offers reason for optimism.
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