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Update: A breast cancer vaccine for people with an inherited BRCA1, BRCA2 or PALB2 mutation

A breast cancer vaccine is showing promise in early clinical trials. Initially, the vaccine was tested in people with triple-negative breast cancer (TNBC) who were at high risk for recurrence. Now the vaccine is being tested to lower breast cancer risk among people with an inherited mutation in BRCA1, BRCA2  or PALB2. It is also being tested in people with triple-negative breast cancer who are at high risk for recurrence and are taking the immunotherapy drug Keytruda (pembrolizumab) after completing chemotherapy. (Posted 1/31/24)

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RELEVANCE

Most relevant for: People at increased risk for breast cancer undergoing prophylactic bilateral mastectomy due to an inherited mutation in BRCA1, BRCA2 or PALB2. People with TNBC who still have breast cancer after chemotherapy..

It may also be relevant for:

  • people with triple negative breast cancer
  • previvors
  • people with a genetic mutation linked to cancer risk

Relevance: Medium

Research Timeline: Human Research

Relevance rating details

What is this update about?

Researchers are studying a new vaccine to see if it lowers the chance of developing breast cancer in people who have a high risk due to an . The study will also determine whether the vaccine reduces the risk for recurrence in people diagnosed with triple-negative breast cancer who are at high risk for recurrence.

In this study update from the 2023 San Antonio Breast Cancer Symposium, researchers found that the vaccine triggers the immune system to recognize a protein found on some breast cancer cells. However, the research is in its early phases and scientists do not yet know how well the vaccine lowers the risk for breast cancer in high-risk people or prevents recurrence in people who have already been diagnosed.

This is the latest update on this vaccine. In May 2021, we originally published an XRAY review of a press release announcing the opening of the initial research study for people diagnosed with . In January 2023, we published an update highlighting how the research study was being expanded to include people at high risk for breast cancer.

Why is this new update important?

Researchers want to know if the vaccine can prevent breast cancer or breast cancer recurrence, but it is not yet known if the vaccine works. Early results show that this new breast cancer vaccine is safe and well tolerated.

The trial was initially open to people with non-metastatic triple-negative breast cancer ().

Two new groups of people can now enroll in the trial:

  • People at high risk of developing breast cancer due to an inherited mutation in , or and are planning risk-reducing mastectomies.
  • People with breast cancer who are taking an drug called Keytruda (pembrolizumab) and still have breast cancer after chemotherapy. 

How does the vaccine work?

Your immune system can defend against cancer. A cancer vaccine can help your immune system find and fight cancer.

Researchers are studying a vaccine that trains the immune system to kill cells that make a protein called alpha-lactalbumin. This protein is found on breast cells during late pregnancy and lactation. Once a person is no longer pregnant or lactating, the protein is no longer made. However, breast cancer cells, particularly TNBC cells, also produce alpha-lactalbumin.

Study findings

Study participants with TNBC received a total of three vaccinations, one every two weeks. Over 10 weeks, researchers looked at how well participants tolerated the vaccine and how well it triggered an immune response.

Early results show that:

  • Researchers were able to identify the dose that triggers the best immune response.
    • All participants had an immune response. regardless of the dose they were given.
      • A strong immune response was seen in 12 of 16 (75%) participants. 
  • The vaccine is safe and well tolerated.
    • No significant side effects were seen at this dose level, other than irritation at the site of injection.