WASHINGTON — A first-of-its-kind cancer vaccine significantly reduces the chances of melanoma patients’ tumors coming back, according to the results of a major study released Thursday by drugmakers Moderna and Merck.
The vaccine was tailor-made for each patient to match their tumor. Adding it to standard postoperative treatment reduces the risk of melanoma recurrence by 42% two years after surgery, according to the most advanced study to date on this new strategy in the fight against cancer.
“The field has been looking for a win and I think this is an important one,” said Dr. Hussein Tawbi of the MD Anderson Cancer Center in Houston, one of the researchers in the international study.
The vaccine, called intismeran, is made with the same Nobel Prize-winning mRNA technology that was behind COVID-19 vaccines. Personalized experimental cancer vaccines mRNA-based and other approaches are also being tested against other types of cancer, including lung, kidney, and pancreatic cancer.
Experts not involved in the new study say its success strengthens the field.
“This is a new frontier,” said Karen Knudsen, CEO of the Parker Institute, which helps fund cancer immunotherapy research.
“This is a big step forward for science and for oncology because this vaccine will be applicable to many different cancers,” said Dr. Michael Atkins, deputy director of the Lombardi Comprehensive Cancer Center at Georgetown University.
Moderna and Merck announced in August that the late-stage trial of intismeran had been successful, but detailed results were expected to be released Saturday at a meeting of the European Society of Medical Oncology in Madrid. Some data was publicly released Thursday evening, resulting in a full release ahead of the weekend’s scientific presentation.
Most people think that vaccines prevent infection, such as measles or whooping cough. There are already two vaccines against cancer, HPV And hepatitis B vaccines which block infection by these tumor-causing viruses. And research is underway to prevent certain types of hereditary cancer, such as colorectal cancer caused by Lynch syndrome.
But a personalized vaccine designed to prevent surgically removed cancer from coming back is very different. For the intismeran study, scientists looked for genetic mutations unique to each patient’s tumor, mutations that create proteins that should not be present in the body unless those cancer cells start growing again. The personalized vaccine – nine doses given three weeks apart – teaches the patient’s immune system to monitor and attack these so-called neoantigens.
How did it work? The study included more than 1,100 people with high-risk melanoma that was surgically removed. Everyone received the standard follow-up treatment: Merck’s immunotherapy called Keytruda. Participants were randomly assigned to also receive custom-prepared vaccine doses or a placebo.
Two years later, 82% of people in the vaccinated group were still living without a recurrence of their cancer, compared to 70% who had received standard Keytruda alone. The trial continues to track participants’ long-term outcomes.
In 2024, Tony Hout joined the vaccine trial at MD Anderson after seeking care for a spot on his ear that bled intermittently and did not heal completely. Doctors recognized melanoma and discovered during surgery that it had started to spread.
“I want to make sure I’m doing everything I can to be here for my family,” said Hout, 62, who has since moved to Cayuga, Indiana, and returns to Houston every few months for a college checkup. Scans this week showed he was still cancer-free.
Side effects from the vaccine were mainly arm pain, fatigue and other reactions typical of the mRNA coronavirus vaccination, said Tawbi of MD Anderson.
Moderna and Merck are discussing next steps with regulators to gain approval for the vaccine.
Personalized medicines are generally very expensive. Drugmakers do not discuss the cost of such a cancer vaccine.
But Moderna President Stephen Hoge said the company’s special cancer vaccine manufacturing facility in Massachusetts was providing doses to thousands of people enrolled in several ongoing studies internationally.
Hoge said it takes a few days to prepare the vaccine, but the entire process, starting with analyzing the tumor’s genetics to coming up with what is essentially a recipe for each patient, can take about six weeks, sometimes longer. Meanwhile, the melanoma patients had already started their standard Keytruda, a different type of immunotherapy.
Moderna shares fell 18% Thursday after the study’s full results were released, but remained more than 200% higher than before. end of August before investors are first informed of the initial results.
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