For years, experts have looked for ways to improve treatment options for people with breast cancer, which remains one of the most common types of cancer in the United States and beyond. But what about preventing the disease?
Cleveland Clinic has begun clinical testing of a novel vaccine designed ultimately to prevent triple-negative breast cancer (TNBC). Oncologist G. Thomas Budd, MD, the trial’s principal investigator, explains what’s happening and how the future of breast cancer prevention may look.
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What is the breast cancer vaccine trial?
This clinical trial is based on two decades of research and laboratory studies by Cleveland Clinic Lerner Research Institute immunologist Vincent Tuohy, PhD, who showed that activating the immune system against a protein called α-lactalbumin prevented breast cancer in mice at risk for the disease. The research, originally published in Nature Medicine, was funded in part by philanthropic gifts from more than 20,000 people over the last 12 years.
Now, a human trial will advance this research into people, focusing on individuals who have completed treatment for TNBC and are at risk of their cancer returning. The goal of the phase-one trial is to determine proper dosage in patients with early-stage TNBC and to optimize the body’s immune response to the vaccine.
“The trial is the first study in a long road that we hope will lead to a vaccine that can prevent at least some breast cancer,” Dr. Budd says. “Our long-term goal is to determine if this vaccine can prevent breast cancer — especially the more aggressive forms of the disease — before it occurs.”
Dr. Tuohy is the primary inventor of the vaccine technology, which Cleveland Clinic has licensed to Anixa Biosciences, Inc. He will receive a portion of commercialization revenues received by Cleveland Clinic for this technology and also holds personal equity in the company.
The U.S. Food and Drug Administration recently approved an investigational new drug application for the vaccine, allowing the clinical trial to move forward. The study is funded by the U.S. Department of Defense.
What will the breast cancer vaccine do?
The vaccine targets the milk protein α-lactalbumin, which is typically expressed only when a woman is lactating. It’s no longer present after lactation in normal, aging breast tissue. But tumors can make this “retired” protein when they’re not supposed to. Studies have found that 70% to 80% of TNBCs produce too much α-lactalbumin.
“The general idea behind the vaccine is that α-lactalbumin could be a so-called immunologic target — where we can stimulate the immune system to attack cells that make that protein,” Dr. Budd says.
The vaccine also includes another drug, an immunologic adjuvant, which essentially calls your immune system’s attention to α-lactalbumin and flags it for an immune response to prevent an emerging tumor from growing.
Why target triple-negative breast cancer?
Triple-negative breast cancer is so named because patients’ cancer cells test negative for estrogen and progesterone receptors and the human epidermal growth factor receptor 2 (HER2) protein.
Hormone therapy and other targeted drugs are ineffective against TNBC. Right now, the only effective prevention method available to those at high risk for TNBC is a mastectomy.
TNBC accounts for 12% to 15% of all breast cancers and is the most aggressive and deadly subtype, with nearly one-quarter of all patients dying within five years of diagnosis. TNBC also disproportionately affects Black women and women with BRCA1 gene mutations.
What will be the next phase of the clinical trials?
The initial stage of the trial is focused on people who have already had TNBC, but eventually, research will expand to study people who are at risk for developing breast cancer.
“This is just the starting point,” Dr. Budd says. “We’re beginning with patients who already have breast cancer and have something to gain from this. Once we figure out the side effects and dosage, we want to study patients who have a genetic risk to develop triple-negative breast cancer.”
Who is participating in the breast cancer vaccine trial?
Participants will have met the following criteria:
- Generally healthy.
- Completed treatment for triple-negative breast cancer but are at risk for the cancer to return.
- Not taking medications whose side effects include lactation or milk production.
And although the trial is open to all genders, Dr. Budd says he doesn’t expect many people assigned male at birth to enter the trial. “Triple-negative breast cancer disproportionally impacts people assigned female at birth,” he says, “though we are open to anyone who meets the eligibility criteria.”
How many participants will there be?
The phase one trial will enroll 18 to 24 people who were diagnosed with TNBC within the past three years and are currently tumor-free but have a high risk of recurrence.
“In phase one, we’ll start out at a low dose of the vaccine, treating one to three patients and monitoring them to make sure they do all right,” Dr. Budd explains. “If those patients have no problems, we go to the next dose; if they do have a problem, we may enter more patients at that dose level, just to make sure it’s safe, and then move from there to subsequently higher dose levels.”
In other words, the number of participants and their dosage levels will ultimately depend on whether doctors observe any side effects in the first few patients.
“Once we’ve figured out how much of the vaccine we can give, we’ll look at its effects on the immune system,” Dr. Budd continues. “That will help us know whether the vaccine is doing what we want it to do, and then we’ll expand each dose level.”
The study is estimated to be completed in September 2022.
Researchers hope future stages will involve healthy, cancer-free individuals who are at high risk for developing breast cancer and have decided to undergo voluntary bilateral mastectomy to lower their risk. These individuals usually have a mutation in the BRCA1 or BRCA2 gene, which puts them at increased risk for developing TNBC. They may also have a high family risk for any form of breast cancer.
What are the potential side effects of the breast cancer vaccine?
The vaccine is still experimental, so there is a potential for as-yet-unknown side effects. And, of course, there’s the possibility that it may not prevent participants’ cancer from returning.
“We don’t know whether it will have a significant effect on the chance of their cancer coming back,” Dr. Budd says.
How will trial participants be monitored?
Participants will be given three doses of the vaccine — one every two weeks — and will be monitored at each visit. They’ll undergo blood tests and physical exams to make sure there are no undue side effects and to monitor their immune response to the vaccine.
“They’ll be monitored thereafter for a total of 84 days, assuming all side effects have resolved,” Dr. Budd says. “If there are significant side effects that haven’t resolved, we’ll continue to follow those participants as needed.”
When will a breast cancer vaccine be available to the public?
On the cusp of opening the first phase of the trial, it’s still far too soon to tell when or if a breast cancer vaccine may be made broadly available. This vaccine strategy also has the potential to be applied to other types of tumors, including ovarian and endometrial cancers.
“It will take years to develop and test something like this,” Dr. Budd says, “because it takes years to see whether you’re preventing a cancer that may occur over a person’s lifetime. But we have to start somewhere — and we’re really excited to take our first step.”
This clinical trial is limited to a very small number of patients. Information about this study, including a description of the study and eligibility criteria, can be found on the ClinicalTrials.gov website. If you have additional questions, you can contact Cleveland Clinic Cancer Answer Line at 216.444.7923 Monday through Friday 8 a.m. to 4:30 p.m. EST or by email at CancerAnswer@ccf.org.
To hear more on this topic from Dr. Budd, listen to the Health Essentials podcast episode “Breast Cancer Vaccine Trial: What You Need to Know.” New episodes of the Health Essentials podcast publish every Wednesday.