How Close Are We to a Breast Cancer Vaccine?

Breast Cancer Vaccine Trials Set to Begin in 2021

Clinical trials for a “potentially paradigm-shifting” vaccine to prevent breast cancer are expected to begin this spring. The U.S. Food and Drug Administration (FDA) recently approved the investigational new drug application for the vaccine, which permits the Cleveland Clinic and Anixa Biosciences to proceed with human trials. Anixa Biosciences, a biotechnology company that focuses on the treatment and prevention of cancer and other infectious diseases, has exclusive worldwide rights to the vaccine.

“This approval triggers a cascade of events and activities, that will eventually lead to recruitment of patients and initiation of the trial,” said Dr. Amit Kumar, president and CEO of Anixa, in a December 20 press release announcing the approval. The breast cancer vaccine was invented and developed by Cleveland Clinic immunologist Dr. Vincent Tuohy and his research team. Dr. Thomas Budd, an oncologist at the Cleveland Clinic, will lead the clinical trial.

The initial focus will be triple-negative breast cancer (TNBC), but the technology is expected to potentially prevent other types of breast cancer, too. TNBC accounts for about 10-15% of all breast cancers, according to the American Cancer Society. Women with TNBC have fewer treatment options and a worse prognosis than those with other types of breast cancer. The vaccine works by immunizing against a protein called the alpha-lactalbumin protein, which is expressed in women's mammary glands later in pregnancy and during lactation. The protein is also expressed when a woman develops breast cancer.  

“Our vaccine immunizes women, teaching the immune system to attack and destroy the cells producing this protein only,” Dr. Kumar said in a recent interview with Drug Discovery and Development. “Thus, the immune system destroys the aberrant cells before they can reproduce and eventually gain critical mass and become a tumor.” Pre-clinical trials conducted on animals showed that 100% of the mice that were not vaccinated and instead received the placebo developed breast cancer and died.

Existing Cancer Vaccines

Medical researchers and pharmaceutical companies have been working to develop a vaccine to prevent breast cancer for years. However, the FDA has not yet approved any. In fact, the agency has only approved two types of preventive cancer vaccines: the HPV vaccine to prevent vaginal and vulvar cancers, anal cancer and genital warts; and the hepatitis B vaccine, which protects against the hepatitis B virus (HBV), which can cause liver cancer.

Most breast cancer vaccines being studied focus on treating the disease after it has occurred rather than preventing it. These treatments are known as immunotherapies because they harness the patient's immune system to fight cancer. For example, Sellas Life Sciences’ NeuVax contains small pieces derived from the HER2 protein. Once injected into the patient, the vaccine “teaches” the immune system to recognize and mount a response against HER2, ultimately killing cancer cells. In clinical trials, the vaccine appeared to delay disease recurrence in TNBC patients with low HER2 expression when added to standard maintenance therapy.

Mayo Clinic immunologists have developed two immunotherapy vaccines against TNBC and HER2 positive breast cancer, respectively, and are working on a third against ductal carcinoma in situ (DCIS) considered the earliest form of breast cancer.

“We know that they have had a positive impact on ovarian and breast cancer,” said Dr. Keith L. Knutson, a professor of immunology at the Mayo Clinic, in an October 2019 interview with Forbes. “We haven’t seen any adverse events that are causing problems other than irritation in the area similar to a flu vaccination. Now we have to convince the FDA, through solid, rigorous clinical trials that we’re seeing what we’re seeing.”

The Challenge of Cancer Vaccines Today

Many more cancer vaccine studies are underway — ClinicalTrials.gov lists more than 300 — but most are for therapeutic vaccines.

It’s unlikely that a single vaccine will be able to prevent all forms of cancer. “Cancer is not a single disease, which means there is a not a universal target,” said Dr. Seth M. Pollack, an oncologist and researcher at the Fred Hutchinson Cancer Research Center in Seattle, in a 2018 interview with U.S. News and World Report. “The vaccine has to tell the immune system to go find something specific, but there's nothing specific that the immune system can look for that is common to all cancers," Dr. Pollack said.

However, there are some targets common to several cancers, such as the MUC1 gene, which is overexpressed in breast, pancreatic and colorectal cancers. The best candidates for a preventive breast cancer vaccine may be women who have mutations in the BRCA1 or BRCA2 genes, according to Dr. Esteban Celis, co-leader of the cancer immunology, inflammation and tolerance program at the Georgia Cancer Center at Augusta University in Augusta, Georgia. 

Those women may undergo mastectomies or have their ovaries removed to drastically lower their risk of breast cancer. (Think: actress Angelina Jolie’s preventative double mastectomy.) Perhaps they could be vaccinated instead. “I would say that the chances of developing a prophylactic vaccine for those instances would be far greater than vaccinating the whole population against cancers," Dr. Celis also told U.S. News and World Report. But he said more work needs to be done before that becomes an option.