Science Friday - mRNA Vaccine For Pancreatic Cancer Continues To Show Promise

Episode Date: August 22, 2025

This month, the Department of Health and Human Services terminated almost $500 million in mRNA vaccine development grants and contracts. While HHS has said that these cuts won't affect mRNA cancer research, some researchers have expressed concern about the impact on their ongoing work. In light of these developments, we’re revisiting a conversation from February.A team at Memorial Sloan Kettering is developing an mRNA vaccine for pancreatic cancer, which is notoriously difficult to treat. A few years ago, the team embarked on a small trial to test the vaccine’s safety. Sixteen patients with pancreatic cancer received it, and half of them had a strong immune response. A follow-up study found that in six of those patients, the cancer hadn’t relapsed after three years.Host Flora Lichtman spoke to study author Vinod Balachandran about the work, which has not yet been affected by the cuts, according to Memorial Sloan Kettering.Guest: Dr. Vinod Balachandran is an associate attending surgeon and Director of The Olayan Center for Cancer Vaccines at Memorial Sloan Kettering in New York, New York.Transcripts for each segment will be available after the show airs on sciencefriday.com.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Flora Lichten. Today on the podcast, fighting a hard-to-treat cancer with a vaccine. This is exciting because we can teach the immune system to recognize other deadly cancers. This month, the Department of Health and Human Services terminated almost $500 million in mRNA vaccine development grants and contracts. As you know, MRI vaccines have been used for infectious diseases like COVID, but researchers are also turning to them for certain cancers. Now, HHS has said that these cuts won't affect MRNA cancer research, but some researchers have expressed concern about the impact on their ongoing work. A team at Memorial Sloan Kettering is developing a new MRNA vaccine for pancreatic cancer, which is notoriously difficult to treat. 90 percent of people who are diagnosed with pancreatic

cancer die from the disease, which is what makes a new possible treatment so exciting. A few years ago, the team embarked on a small trial to test the vaccine's safety. Sixteen patients with pancreatic cancer got it. And even though it was a small study, the results were promising. Half the patients saw an immune response. And in a follow-up study, they found that in most of those patients, the cancer hadn't relapsed after three years. We spoke to study author Dr. Vinod Balasandran earlier this year about the work, and we wanted to re-air the conversation in light of the recent cuts to MRNA research.

This work has not yet been affected by the cuts, according to Memorial Sloan Kettering. Vinod, welcome to Science Friday. Thank you for having me, Flora. So why is it so difficult to treat? So this is an interesting question, and you might think it quite simple to answer, but... No, I never think it's simple when I ask a science question. Well, it is deceptively simple, but notoriously still hard for us to answer this. Why is pancreatic cancer, in fact, so challenging to treat when we've made so much progress in many of the other common cancer types, such as breast cancer, prostate cancer, ovarian cancer, etc. And as you may know, pancreatic cancer is now the second leading cause of cancer death in the United States in 2025. and second only to lung cancer.

Now, one of the reasons is because we have made tremendous progress in outcomes for many of the other more common cancer types, newer waves of oncology drugs, and these drugs have had more impact on the other common cancers, but have not impacted outcomes in pancreatic cancer patients. Do we know why? So the prior thinking had been that perhaps the immune system could not recognize pancreatic cancer because it was perhaps too difficult or too challenging to recognize. And because of that, an immune therapy that would boost immune recognition of cancer

would not be effective in pancreatic cancer. So in fact, this is one of the interesting conclusions from some of the work that we have done is that this does not appear to be the case. And you can use vaccination to teach the immune system to recognize pancreatic cancer. So I think this is exciting because hopefully this can lead to novel ways through which we can teach the immune system to recognize other high, unmet need, and deadly cancers. Right. It upends the the assumption that some cancers just can't be treated with immunotherapy. That's correct.

The assumption had been that the primary way we think the immune system recognizes a cancer as foreign. As you know, the immune system is hardwired to recognize pathogens such as viruses and bacteria as foreign, and these pathogens are non-self, if you will. cancers are however self they are derived from our own tissues and the immune system is in fact programmed to not recognize ourselves as foreign so for the immune system to recognize cancer you have to teach it exquisitely to recognize the portions of the cancer that are foreign and what we have learned over the past few decades is one of the primary ways through which the immune system recognizes a cancer is

for and is by identifying and recognizing mutated proteins that are found on the surface of cancer cells. So a mutation or a break in the DNA is in fact how a normal cell becomes a cancer cell. The break in the DNA or a mutation causes this normal cell to start dividing abnormally and become cancerous. But through that process, as the cancer cell continues to divide and grow, it accumulates many more of these mutations. So genetic errors. And some of these genetic errors produce new proteins and they serve as red flags, alerting the immune system that this cell is not behaving properly and needs to be eliminated. So the immune system can spot them.

Exactly. Yeah. So I want to talk about the vaccine that you and your collaborators developed. It's an MRNA vaccine. And I think many people are familiar with mRNA vaccines, you know, from COVID. How is yours different? Right. So a MRNA vaccine for COVID-19, you know the virus. It is the same virus that affects the entire population. Therefore, you can make one vaccine and administer it to the whole population to protect it. But in cancer, since these red flags are individual to each person's cancer, these vaccines for cancer have to be individualized for each patient. So this is a key difference. So the flags are different. You could have the same cancer, but the flags that appear on cancerous cells would be different.

person to person. That's correct. So because the flags are different for each individual and potentially each individual cancer, vaccines have to be individualized for each patient. And that's what you did, right? And that is what we did for pancreatic cancer. That's correct. In this clinical trial, patients had surgery for pancreatic cancer here in New York City. And within 72 hours, we shipped the tumors to colleagues in Germany where they did genetic analysis of the tumors and then individually made a bespoke vaccine for each patient and then shipped them back to us. And then we began administering their vaccines nine weeks after their surgery. And a feature that allows individualization in a rapid manner is the RNA vaccine technology.

So you made a vaccine. for each individual based on samples of cancerous cells. Does that mean this vaccine only works after you've had cancer? So at the current time, we do need to know what the flags are because we then incorporate those flags in an individual vaccine for each patient. So at the moment, we are able to only create a vaccine after we genetically analyze and identify the flags. I hear you saying at the moment, and I'm intrigued. Yes. So you could envision perhaps over time as we accumulate more and more information on the flags. Could you then create a library of flags, which could then serve as a basis for a preventative vaccine in the future for an

individual cancer? So this remains a hypothesis and something that would be an interesting area of exploration in the future. But for us to learn how to do that, we believe these current vaccines, which are preventing cancers from coming back after they have been removed with surgery, will be a key component to understanding the hows of an effective vaccine for cancer. If you could make the vaccine quick enough, could the vaccine also be used as a treatment to wipe out tumors that are, that currently exist? This is also an important. question. Currently, it looks like the vaccines would work best when they are administered to prevent something from occurring or reoccurring. That's what makes them a vaccine not a drug.

Exactly. Yeah. Could there be ways we might be able to use it for therapy in the future? It's possible. But as of now, I think this still remains an area of active investigation. After the break, what's the future of this approach? Could we ever get to vaccines to be able to? to prevent cancers before they occur. We hope to get there. Let's talk about this latest study. You followed these same patients who were in the previous study, who were in this very small trial. What are you reporting this week? Right. So in this clinical trial, we vaccinated 16 pancreatic cancer patients with custom vaccines made with RNA. And the goal here in this trial was to teach patients' immune systems to recognize their own individual cancers. And from a broader sense,

what do you need for an effective vaccine against cancer? Well, what you need is a vaccine that makes lots of T cells. T cells are specialized immune cells in the body that protect us from infections in cancer. And you need these T cells to stick around in the body for long periods of time and continue to function. So this was a key question that we wanted. wanted to examine in these patients, namely, could our vaccination strategy, in fact, not only make many T cells, which we had reported earlier in 2023, but do these T cells, in fact, last in these patients, and do they continue to work? Did they?

So what we found here is that, surprisingly, not only do they stick around, they appeared to have the potential to stick around for many, many years. So the average lifespan that we estimated for these T cells was approximately seven years. And in many patients, this number was even higher. So I think the take home from that was that, yes, they do stick around. And yes, they still work. So these are all, we think, have been key barriers for developing effective cancer vaccine. So this was exciting to see that perhaps this particular vaccination strategy that we had

used is a blueprint to make T cells that last and work and could do so even in the most challenging of cancers. I know that this was a phase one trial. You're looking at it's small. You're looking at safety. But did you see any direct evidence that these immune cells were actually attacking cancer cells? That they were doing the job you wanted them to do. So this is a important. question that you're bringing up, namely, are the T cells that are made by the vaccine doing anything? Because in this scenario, we're vaccinating patients when they do not, in fact, have visible cancer. So I think the closest evidence we have for this was that in the patients in whom the vaccines made T cells, three years after surgery, only two of eight of these responders have seen their cancers return.

and in contrast, in the other eight patients who received the vaccines, but the vaccines did not make T-cells, seven of eight of these patients have seen their cancers return after surgery. So these are all correlative pieces of information that are all pointing to the vaccines, perhaps doing something. But this requires more extensive, larger testing and larger clinical trials. And we have a larger phase two clinical trial that is currently ongoing to test the exact question. So you had to, you partnered up with pharmaceutical companies. You mentioned Bayntec to work with you. Was that a difficult cell? I mean, how did you convince them to take this

risk, given that pancreatic cancer has been so difficult to treat? Right. So pancreatic cancer, as I had mentioned to you, historically has been thought of perhaps as vaccine unsuited because of the fact that it has very few of these flags. So if you have very few of them, perhaps, why would you pick pancreatic cancer as a cancer to vaccinate against? And we had done some work going back now 2017, where we had examined rare survivors of pancreatic cancer. So these are the rare 10% of pancreatic cancer patients that receive treatments

that other pancreatic cancer patients do, but have exceptional long-term survival And our question really there had been, well, what makes these patients different compared to the other patients? And what we had found in them is that they appear to generate natural immune responses against their pancreatic cancers. So they have T cells that can recognize their red flags in their cancer spontaneously. And this might be impacting their long-term survival. So this was really the motivation for the clinical trial because it raised the question. question, well, if this is happening in the best case scenario in the survivors, could you then

replicate this with a vaccine? And this is when we approached our colleagues, both at Genentech and Bioentec, with this idea to vaccinate pancreatic cancer patients with RNA vaccines. And yes, this perhaps was not a very popular idea because pancreatic cancer has a track record of drugs not succeeding, but our work was indicating otherwise. And to their credit, they followed the science and this led to this phase one, the first phase one clinical trial of RNA vaccines for pancreatic cancer. So kudos to that. Do you see patients? Yes, I do. Were any of your patients among the trial participants who had, you know, this good outcome? Yes, some of my patients were also on this phase one clinical trial, and this has been a real joy for me to potentially provide them with

new options. So I think this has been something that really serves as a primary motivation for me to keep trying to make progress in pancreatic cancer patients. I mean, it must be very moving for you. This is such a devastating diagnosis for people to have even a potential new avenue for treatment must feel really profound. Well, I think watching patients and their families really battle this disease on daily basis really, I think, is the greatest inspiration for all of us to really push forth, forge ahead and really try to make progress. And we're really privileged to be able to take part in these types of clinical trials

with their support and participation. With a personalized vaccine, is cost? going to be a barrier to getting it to patients who need it? So I think the hope will be that if we can develop effective vaccines for cancer, personalized or not, this will lead to widespread application across a variety of different cancer types, which would bring down the cost. Where do you think we're headed? Do you think we're going to see a preventative vaccine?

for pancreatic cancer or a sort of more universal cancer vaccine in your lifetime? I think these are very intriguing and forward-looking hopes of the community. Could we ever get to vaccines to be able to prevent cancers before they occur? We hope to get there, but I think to get there, we have to focus on the science and really understand how these vaccines might be working in a sense. secondary prevention, namely preventing cancers from coming back after surgery. This will hopefully provide us with important clues on how we might be able to use these vaccines for primary prevention for pancreatic cancer or even for other cancer types. So I think it's really quite an exciting

global vaccine moment that we are in. And I think we have many more exciting advances to come in upcoming years. Come back and tell us about the results of your phase two trial, please. We would love to do that. Thank you for taking the time today. Thank you so much. Dr. Vinod Balasandran is Associate Attending Surgeon and Director of the Olayan Center for Cancer Vaccines at Memorial Sloan Kettering, based in New York City. And that is about all we have time for.

Lots of folks helped make the show happen, including... George Harper. John Denkoski. Annie Niro. Jason Rosenberg. I'm Flora Lichtman. Thanks for listening.