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Five years ago, a small group of cancer scientists, gathered in a restaurant at a deconsecrated church hospital in Mainz, Germany, hatched a bold plan: They would test their new cancer vaccine against one of the deadliest forms of the disease, cancer. It is reputed to work backwards even in patients who have had their tumors removed.
Some scientists have discovered that the vaccine may not stop these relapses. But the patients were desperate. And the speed with which the disease, pancreatic cancer, recurs can benefit scientists: for better or worse, they will soon find out if the vaccine has helped.
On Wednesday scholars reported results that defied long odds. The vaccine triggered an immune response in half of the patients treated, and these people did not show any cancer relapse during the study period, a result that outside experts described as very promising.
The study, published in the journal Nature, was a milestone in the years-long movement to make cancer vaccines tailored to individual patients’ tumors.
Researchers at Memorial Sloan Kettering Cancer Center in New York, led by Dr. Vinod Balachandran, extracted the patients’ tumors and shipped samples to Germany. There, scientists at BioNTech, the company that made a highly successful Covid vaccine using Pfizer, analyzed the genetic makeup of specific proteins on the surface of cancer cells.
Using this genetic data, BioNTech scientists have produced personalized vaccines designed to teach each patient’s immune system to attack tumors. Like BioNTech’s Covid shots, cancer vaccines have relied on messenger RNA. In this case, the vaccines instructed the patients’ cells to make some of the same proteins found in the excised tumors, potentially triggering an immune response that could be beneficial against the actual cancer cells.
“This is the first demonstrable success — and I would call it a success, despite the preliminary nature of the study — of an mRNA vaccine in pancreatic cancer,” said University of Texas disease specialist Dr. Anirban Mitra. Anderson Cancer Center, which was not involved in the study. “By that standard, it’s a milestone.”
The study was small: Just 16 patients, all white, received the vaccine, which is part of a treatment regimen that also includes chemotherapy and a drug aimed at preventing tumors from evading people’s immune responses. The study could not rule out factors other than the vaccine, which contributed to better outcomes in some patients.
“It’s relatively early days,” said Dr. Patrick Ott of the Dana-Farber Cancer Institute.
Moreover, “cost is a major barrier to wider use of these types of vaccines,” said Dr. Neeh Zaidi, a pancreatic cancer specialist at Johns Hopkins University School of Medicine. This can lead to access discrepancies.
But the simple fact that scientists could create, test and deliver personalized cancer vaccines so quickly — patients began receiving the shots intravenously about nine weeks after tumors were removed — was a promising sign, experts said.
Since the study’s inception, in December 2019, BioNTech has shortened the process to less than six weeks, said Dr. Ugur Sahin, one of the company’s founders, who worked on the study. Ultimately, the company intends to be able to make cancer vaccines within four weeks.
Since I first started testing vaccines about a decade ago, Dr. Shaheen said, I have brought the cost down from $350,000 per dose to less than $100,000 by automating parts of production.
And the two companies announced last month that a personalized mRNA cancer vaccine developed by Moderna and Merck reduced the risk of relapse in patients who had surgery for melanoma, a type of skin cancer. But the latest study set the bar even higher by targeting pancreatic cancer, which is thought to have fewer genetic changes that make it ripe for vaccine therapy.
In patients who did not seem to respond to the vaccine, the cancer tended to return about 13 months after surgery. Despite this, patients who responded showed no signs of relapse during the approximately 18 months they were tracked.
Interestingly, one patient showed evidence of a vaccine-activated immune response in the liver after an abnormal growth there. The growth later disappeared on imaging tests.
“It’s anecdotal, but it’s good confirmatory data that the vaccine can reach these other tumor areas,” said Dr. Neena Bhardwaj, who studies cancer vaccines at the Icahn School of Medicine at Mount Sinai.
Scientists have struggled for decades to create cancer vaccines, in part because they have trained the immune system on proteins found in tumors and normal cells alike.
Tailoring vaccines to mutated proteins found only in cancer cells could potentially help trigger stronger immune responses and open up new avenues for treating any cancer patient, said Ira Millman, vice president of cancer immunology at Genentech, which developed the pancreatic cancer vaccine using BioNTech technology.
“Just a proof of concept that vaccines in cancer can do something after, I don’t know, thirty years of failure maybe it’s not such a bad thing,” said Dr. Millman. “We’ll start with that.”
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