Cancer researchers are seeing promising signs for mRNA vaccines as a treatment for cancer, but the work has been buffeted by political backlash, funding disruptions, and the usual top-down gatekeeping that decides which lives get backed and which get left waiting. For Vita Sara Blechner, a middle school librarian from Oceanside, New York, the stakes were immediate: on March 7, 2020, she went to the emergency room after feeling shooting pains in her back that an acid reflux pill did not relieve, and doctors found a tumor on her pancreas after a sonogram and CT scan.
Pancreatic cancer is notoriously unforgiving: just 1 in 4 patients lives a year after diagnosis, and just 1 in 10 makes it two years. Blechner spent two anxious days in the hospital before going home and weighing her options with her husband and their three adult sons. That search led her into cancer research involving messenger RNA, or mRNA, a single-stranded molecule that delivers genetic information from DNA to direct the formation of proteins.
Who Gets to Decide What Gets Funded
mRNA is known to most people from high school science classes or for its use in Covid vaccines, but long before Covid it was generating intense excitement in the cancer research community. BioNTech, the German company that designed the Covid vaccine for Pfizer, adapted that vaccine from a platform it had been using to develop cancer treatments for nearly a decade. The same platform that helped blunt the impact of the pandemic also sparked political backlash that, in the past year, has threatened to slow or derail dozens of potential cancer treatments.
Researchers say there are signs the mRNA effort is still on track. Elizabeth Jaffee, deputy director of the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, said, “It’s exciting,” and added, “There’s been a number of successes in early-stage, positive trials.” Catherine Wu, a professor of medicine at Dana Farber Cancer Institute and Harvard Medical School, said recent positive real-world results helped drive the National Cancer Institute’s announcement that it would help raise $200 million specifically for novel cancer vaccines. Wu said, “We’re getting a lot of support from NCI in terms of developing and promoting cancer vaccines, and mRNA vaccines are a major part of that portfolio.”
Blechner turned to doctors at Memorial Sloan Kettering Cancer Center, including Dr. Vinod Balachandran, director of MSK’s Olayan Center for Cancer Vaccines. Balachandran said it is more challenging to make a vaccine against cancer than against a virus or bacteria because the immune system is already hard-wired to recognize viruses and pathogens as foreign, while cancer is derived from the body’s own tissues. He said much of his work over the past two decades has focused on pancreatic tumors because “It’s a cancer where nothing had really worked.”
The Trial, the Lab, the Long Wait
When Blechner arrived at MSK, Balachandran was launching a trial of an experimental mRNA-based vaccine against pancreatic cancer, combined with standard immunotherapy and chemotherapy. He said a successful vaccine could have wider application and that if researchers could crack the toughest cancer, “it could unlock how to crack the other [types of cancer], because it would provide a blueprint.” To develop the vaccine, he studied “super-survivors,” the fewer than 10% of pancreatic cancer patients who live more than five years from diagnosis. He found their immune systems were especially good at spontaneously recognizing cancer cells as foreign.
Balachandran said these patients had about 12 times as many T-cells inside their tumors as average patients, and the same T cells were circulating for more than a decade in some cases. He also said these T cells were recognizing mutations and that each person’s immune system was recognizing its cancer in a very specific way. He said, “To replicate this would require us to teach each individual person’s immune system how to recognize their individual cancer. It would be an individualized vaccine. And we felt the best technology for rapid custom cancer vaccination was to use RNA.”
After Blechner signed on for the trial, she underwent a Whipple procedure to remove the tumor in the head of her pancreas. In a lab at MSK, the tumor was preserved and sliced into fine pieces, each thinner than a human hair. In less than 72 hours, the package was sent to Germany, where BioNTech technicians processed the material into a clear liquid personalized vaccine custom-made for Blechner.
A little more than two months after her diagnosis, the vaccine arrived back in New York. By then, she had received a dose of an immune checkpoint inhibitor, an immunotherapy drug designed to make immune cells more effective in fighting cancer. For weekly infusions of the vaccine, her husband, Simon, drove her from Oceanside to the MSK hospital on Manhattan’s East Side. During the height of the Covid pandemic, he would drive through empty streets and wait back home on Long Island while Blechner lay in a hospital bed for eight hours during each infusion.
After nine weeks, she finished the vaccine phase and moved to chemotherapy, but the chemo was a fiasco. Blechner said she suffered severe side effects, was hospitalized three or four times, lost weight until she was down to 90 pounds, had no appetite, was constantly nauseous and had liver damage. She said, “I got very sick,” and, “My doctor said to me she never thought she’d see me again.” She had only three chemotherapy sessions before treatment was halted. By the time she felt strong enough to try again, doctors said it would be unsafe to resume.
What the Results Say, and Who Controls the Pipeline
More than six years later, Blechner is still doing well and shows no sign of cancer. Of 16 patients in Balachandran’s trial, eight showed a dramatic immune response to the mRNA-based vaccine, and seven of those eight are alive and well six years after the trial began. Those findings were to be presented Monday at the American Association of Cancer Research meeting in San Diego. Balachandran said, “It’s exciting,” and added, “The implication is that you can make a very strong immune response against the toughest of cancers, and it can last for this long. So if you could do it here, you could potentially do it in many other cancers.” He said a larger multisite trial has been underway for a year.
The announcement came after other encouraging news for pancreatic cancer patients. Earlier this month, the New York Times published an interview with former US Sen. Ben Sasse of Nebraska, who has advanced pancreatic cancer and said he had been taking an experimental drug that caused his tumors to shrink, though with painful side effects. Last week, Revolution Medicines, the California-based biotech company running the phase 3 trial that Sasse is part of, said in a news release that for patients whose cancer had spread, the drug nearly doubled survival time to 13.2 months, compared with 6.7 months among participants who did not get the drug. Revolution said it would seek approval from the US Food and Drug Administration for the drug, daraxonrasib.
The field has also faced backlash since the pandemic. In March 2025, scientists reported that the acting director of the National Institutes of Health, Dr. Matthew Memoli, had sent a letter asking that all grants, collaborations or contracts involving mRNA be flagged. In May, the White House proposed a cut of more than 40% to funding for the National Cancer Institute. Twenty-six days later, the US Department of Health and Human Services canceled a $590 million deal with Moderna to develop an mRNA-based vaccine against emerging pandemic influenza. In August, HHS said it would no longer fund mRNA research through the Biomedical Advanced Research and Development Authority, a move involving the cancellation of 22 separate contracts.
More recently, the FDA canceled its review of Moderna’s mRNA-based flu vaccine, criticized the design of the company’s clinical trial, and then reversed its decision a week later after criticism. FDA Commissioner Dr. Marty Makary said the agency bears no animus toward mRNA and terminated contracts last year solely to save taxpayer money, saying at a news conference in February, “The companies that made mRNA vaccines made over $50 billion. They can fund their own research.”
Researchers said the external threats have been real. Wu said, “The external threats are real,” and, “It forced us to really step back and think. I wouldn’t be genuine if I said we weren’t all concerned.” Dr. Ryan Sullivan, director of the Center for Melanoma at Mass General Brigham Cancer Institute, said mistrust of mRNA vaccines since the pandemic has at times made it harder to recruit people into clinical trials. Sullivan said, “Most people don’t have significant concerns, but some are reluctant,” and, “The skepticism over vaccines in general is a little bit lessened around cancer vaccines, but not totally, and some people are resistant to the concept, even when they’re fighting cancer.”
Sullivan is an investigator on multiple studies with mRNA vaccines, including a large-scale trial run by Moderna and Merck testing an mRNA-based therapy with Keytruda for melanoma. In January, the companies announced that the combination cut the death rate for participants in their study by 49% over five years. A larger phase 3 trial is underway, and the companies are also testing the therapy against non-small cell lung cancer, bladder cancer and renal cell carcinoma. Like the vaccine that helped Blechner, the melanoma treatment is personalized, using an individual patient’s tumor cells to engineer a highly specific immune response.
Another approach involves generalized or off-the-shelf vaccines that are not tailored to each patient. BioNTech and the Moderna/Merck collaboration are both working on approaches that use mRNA to encode and deliver a predefined set of antigens, immune targets typically shared across patients with a given tumor type, in hopes of stimulating a more aggressive immune response. Dr. Elias Sayour, a pediatric oncologist and researcher at the University of Florida, has gone further in the generic direction, testing mRNA vaccines that do not code for any specific antigen at all. In a study published last year in Nature Biomedical Engineering, Sayour treated mice with a generalized vaccine using mRNA to stimulate production of a protein called PD-L1, making tumors more susceptible to immunotherapy.
Sayour said, “We’ve discovered that mRNA doesn’t need to be specific, to reprogram the immune response,” and, “We’re trying to create a new paradigm,” adding, “It takes weeks to create a personalized vaccine. The idea of universalization is to wake up the immune system more rapidly.” Sayour said the two approaches could complement each other, with a newly diagnosed patient potentially receiving an off-the-shelf vaccine first and a personalized vaccine later.
A recent illustration of the universal vaccine approach came in a study led by Drs. Adam Grippin and Steven Lin of MD Anderson Cancer Center. They reviewed records of more than a thousand cancer patients treated with immune checkpoint inhibitors and found that getting an mRNA-based Covid vaccine was linked to a significantly better response to cancer drugs. Patients with small cell lung cancer who had gotten a Covid shot within 100 days of starting treatment lived nearly twice as long as those who had not. For melanoma, researchers could not calculate the difference in survival time because so many vaccinated patients were still alive. Grippin said, “Most people think about vaccines as a laser-guided missile,” and, “That may be true, but our research suggests that mRNA also acts as a siren call to the overall immune system.” Grippin is now collaborating with Sayour to plan a trial in which patients will be intentionally given a Covid vaccine before starting cancer treatment.
Dr. Robert Vonderheide, director of the Abramson Cancer Center at the University of Pennsylvania and president-elect of the American Association for Cancer Research, said the field took hits last year but public pressure turned the tide. He said, “The entire country has been asking, ‘How valuable is cancer research to our society?’ And what we heard from the public and our patients is, it’s super-important.” Federal research grants have started to flow again after major interruptions over the past several months. Last week, NCI Director Anthony Letai told the Cancer Letter podcast that 22 competitive grants were awarded March 17 and another 167 were awarded over the next three-plus weeks.
Still, there are scars. One of Sayour’s proposals, to test an mRNA-based vaccine against a rare form of childhood brain tumor, was approved by the NCI last year, but after the agency reduced by nearly half its total number of awards, Sayour said the money never arrived. He said he expects the work to go forward eventually, but it will take time to find funding. Sayour said, “As you can imagine, I’ve shifted my approach to finances,” and, “The reality is, there’s a lot of dependency on the federal government, and if you put all your faith in one stock, you could go under pretty quickly.”
While federal funding remains tight, the most prominent mRNA cancer vaccines have attracted industry support and are not reliant on grants. Moderna says it expects to release data from the phase 3 melanoma trial this year. Genentech and BioNTech are sponsoring the global multisite test of the vaccine Blechner received, with Balachandran leading efforts at MSK. Balachandran said, “You need a platform that is fast and potent, flexible and scalable,” and, “There are other ways to generate immune responses, but the RNA platform at the moment seems to be superior.” Jaffee said, “We’ve seen two-billion-plus injections, and there’s no data to show that mRNA vaccines cause any serious problems.”
Blechner said that once she hit her fifth year cancer-free, it really sank in that she was doing well. She said, “I beat the odds.” She added, “Now I’m grateful every day,” and said she is looking forward to her sons getting married, to the holidays, and to having the strength to do the work and have everyone over. She said, “We just had a family event a week ago, and we danced and ate and had a great time. Every day is wonderful.”