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Breast cancer vaccine developments have reached milestones that researchers once thought were just far-off dreams. Now the prospect of one day eliminating breast cancer entirely is more real than ever. 

Critical Values spoke with Powel Brown, MD, PhD, professor at MD Anderson Cancer Center in the Department of Clinical Cancer Prevention. As a cancer researcher and oncologist, Dr. Brown believes this is one of the most exciting times in the history of breast cancer research. 

Dr. Brown has a PhD in immunology, in addition to his medical degree. Even back in the 1970s and 1980s, he believed the immune system was the key to eliminating cancer. But early efforts weren’t successful. Only now, in the past 10 years, has the dream of eliminating cancer become a real possibility.  

As part of his cancer work, Dr. Brown is involved with the Cancer Vaccine Coalition. In January 2024, the group launched with an ambitious goal: to finalize the development and deployment of a breast cancer vaccine for all. The Cancer Vaccine Coalition involves people from across many industries, from media to science, policy, and more. 

Here, Dr. Brown shares his insights about breast cancer vaccines and how the Cancer Vaccine Coalition is helping the field gather momentum. 

Critical Values (CV): Tell us more about your background and area of specialty. 

Powel Brown (PB): I’m a physician scientist at MD Anderson and a breast medical oncologist. Pretty early on, I took care of a lot of people who had metastatic breast cancer. Even cycling several chemotherapies, people would succumb to metastatic breast cancer. So, 30 years ago, I said, "We need to do it differently." If we could cure some breast cancers by catching it at stage one or two, what happens if we catch it before that? What if we intervene even before people know they have breast cancer? So, for most of my career, I've been focused on developing ways to prevent cancer. 

CV: How do current strategies fall short?  

PB: There are multiple kinds of breast cancer, such as estrogen receptor-positive, hormone-receptor positive (HER2-positive) or triple-negative. Some patients may also have a BRCA1 or BRCA2 mutation. These can all affect medication options. But virtually all our preventative strategies have some degree of toxicity that women are not willing to endure if they don’t have cancer, unless they are at extremely high risk. This makes finding vaccines with few side effects so important. But I’ve never before in my entire career been as optimistic as I am right now. 

CV: Where are we in breast cancer vaccine research right now?  

PB: In the last 10 years, there’s been a lot of movement forward, including efforts to create a vaccine for HER2-positive breast cancer. Beth Mittendorf, MD, PhD, who’s now at Harvard, is testing an anti-HER2 vaccine. Nora Dsis, MD, at University of Washington, has tested several anti-HER2 vaccines. Brian Czerniecki, MD, PhD, at Moffitt Cancer Center, has tested another anti-HER2 vaccine. We have several different formulations of the vaccine that have been tested, and at least one of which is going to be moving forward to phase two.  

Now for triple-negative breast cancer, George Budd, MD, at Cleveland Clinic did an early phase cancer prevention trial using a vaccine against alpha-lactalbumin, which is a protein that lactating breasts produce. Some triple-negative breast cancers also produce it. He tested a vaccine against this and showed that it was safe, tolerable and you could induce an anti-lactalbumin response in individuals who had triple-negative breast cancer.  

Nora Disis is also working very aggressively to develop triple-negative breast cancer vaccines. She’s tested two very promising ones. One she calls STEMVAC. It’s a vaccine targeting cancer stem cells. I think it’s in the earliest phase of clinical trials, but it has great promise.  

There’s another vaccine, a MUC1 (Mucin 1) vaccine, that’s been developed by Olivera Finn, PhD, an investigator at the University of Pittsburgh. This vaccine is being tested for the treatment or prevention of several cancers including breast cancer. 

Virtually all these vaccines are either in phase one or just moved to phase two. While there is great promise for these vaccines, with the exception of the HPV vaccine, there are no vaccines that have yet reached phase three testing for cancer prevention.   

CV: In your own words, tell us about the Cancer Vaccine Coalition and how it’s helping with this effort?  

PB: The Cancer Vaccine Coalition's goal is to develop strategies to both treat and prevent breast cancer through vaccines. Part of the whole idea of this foundation is to raise money philanthropically to accelerate drug development of vaccines for cancer prevention and cancer therapy.  

Now that we have the technology to do this with RNA-based vaccines, a better understanding of the immune system, and all this new early-phase clinical trial data, if we had the resources, we could supercharge the whole field to develop clinical useful and tolerable vaccines. And that’s what the Cancer Vaccine Coalition is all about. Getting people together who are experts and really passionate about vaccine development, to prevent this disease.  

CV: Has bringing a breast cancer vaccine to the market ever been tried before? And if so, why didn’t it work?  

PB: There's been a desire to develop cancer-preventative vaccines for 40 or 50 years. Early studies targeting the immune system back in the 1980s and 1990s targeted things called cytokines, and they were very toxic. Then they sometimes used the cancer cells themselves as a vaccine, but that didn't work out too well either.  

It really has taken the understanding of immune checkpoint therapy that Jim Allison, PhD, won the Nobel Prize for. That’s the therapy that works for melanoma. In a nutshell: our immune system is capable of reacting against cancer cells. But it also has cells that suppress the anti-cancer immune system. And so all these efforts didn't work because our body had a suppressive mechanism in place. 

Once they learned which cells those immune suppressive cells were, they had to develop ways to stop the suppression. And they successfully did that. 

Prior to that understanding, which has only been in the last 10 or 15 years, we were failing. Now, anti-cancer immunity interventions can work. In the vaccine setting, we might need to suppress that immune suppressive system too. We're testing in the laboratory combinations of vaccine plus checkpoint inhibitor therapy to see if that would work even better. 

But one other problem is the checkpoint inhibitor therapy that we currently have is kind of toxic. And so most people without cancer aren't going to want to take that one. But that's just drug development, right? We now know what to do and how to do it. We just need to have drugs that are a little safer. 

CV: Bringing a breast cancer vaccine to the market is ambitious. Do you foresee a scenario where women are just given an overall breast cancer vaccine, kind of like the HPV vaccine? 

There are two ways to go. One is like the HPV vaccine. In that case, we would give all women the breast cancer vaccine and be done with it. It really depends on the side effects of the vaccines. And since these vaccines are being developed now, we don't really know their side effects yet.  

So, the answer to your question is maybe. Maybe there will be a vaccine that's given to everybody at an early age, and we don't need to worry about breast cancer. That's a possibility.   However, since there are some many different forms of breast cancer, I don’t think a “general breast cancer vaccine” is likely to be effective. 

It may be more effective and safer to identify those people that are at high risk of specific forms of breast cancer and give them a vaccine specific for the breast cancer they are likely to develop. So instead, this would be more like the pneumonia vaccine that we use now. Not everybody's getting the Pneumovax vaccine. It’s given to people of a particular age. So maybe you get the breast cancer vaccine if you are found to have some predisposition, such as an alteration in the BRCA1 or 2 gene. 

But could the vaccines potentially be used in people that never had cancer? The answer is yes. They might also be used as therapeutic vaccines. All of it is possible.  

CV: How long do you think it will be before we see a breast cancer vaccine on the market?  

The therapeutic vaccines will be available quicker because their clinical trials go faster than preventative vaccines. With true prevention trials, you have to wait until people get cancer, so it can take 10 or 15 years to do sometimes.  

I think some therapeutic vaccines will be available in three to five years. Preventative ones may take longer; this is my personal opinion, but I think within 10 to certainly 20 years, we’re going to have a preventative vaccine for breast cancer that’s used routinely. They’re already well on their way. 

CV: How is the Cancer Vaccine Coalition helping speed up that timeline?  

PB: We have the perfect storm right now. The scientific community has discovered that modulating the immune system can have profound effects on cancer. It can cure some cancer patients, and we truly believe it can prevent breast cancers as well.  

And because of COVID, we have a great acceleration of vaccine development and a new technology with RNA-based vaccines… And we have a community of extremely passionate people, coupled with industry and philanthropic donors, and passionate advocates who have the same vision.  

The Cancer Vaccine Coalition is about generating enthusiasm, money and collaboration across these groups. With the support the Cancer Vaccine Coalition can develop, it can hyperdrive the whole drug development field and clinical testing field.  

I’ve never been more optimistic about developing a vaccine and eliminating breast cancer as a major problem. I have three daughters who are at risk of all this, and two granddaughters also at risk. I think within their lifetimes, they're not going to have to worry about breast cancer. I believe through the efforts of the Cancer Vaccine Coalition and other research programs, we are going to see breast cancer virtually eliminated.