Experimental Immunotherapy Medicine Works Similarly in Black and White Women With Triple-Negative Breast Cancer
When more Black women diagnosed with early-stage, triple-negative breast cancer joined a study on Imfinzi (chemical name: durvalumab), the results showed the immunotherapy was as effective in Black women as it was in women of other races and ethnicities.
The research was published online on July 29, 2022, by the journal Clinical Cancer Research. Read the abstract of “Clinical Outcomes and Immune Markers by Race in a Phase I/II Clinical Trial of Durvalumab Concomitant with Neoadjuvant Chemotherapy Therapy in Early-Stage TNBC.”
Doctors call treatments given before surgery neoadjuvant treatments.
Black women and breast cancer clinical trials
According to a 2020 study, only about 8% of eligible people choose to participate in clinical trials for new medicines and other treatments. But this statistic is even worse for Black people. According to the American Cancer Society and the U.S. Centers for Disease Control and Prevention (CDC), Black people made up 12% of new breast cancer cases in 2020 but only 3% of the participants in breast cancer clinical trials that led to U.S. Food and Drug Administration (FDA) approvals between 2008 and 2018.
We also know that Black women are more likely to be diagnosed with triple-negative breast cancer.
About triple-negative breast cancer
Triple-negative breast cancer is breast cancer that is:
Triple-negative breast cancers don’t respond to hormonal therapy medicines or medicines that target the HER2 protein.
Until recently, chemotherapy was the main treatment for triple-negative breast cancer. But in 2021, the FDA approved a new treatment to treat early-stage, triple-negative breast cancer with a high risk of recurrence (the cancer coming back):
the immunotherapy Keytruda (chemical name: pembrolizumab) plus chemotherapy before surgery
Keytruda alone after surgery
Like Keytruda, Imfinzi is a type of immunotherapy medicine known as an immune checkpoint inhibitor. To start an immune response to a foreign invader, the immune system has to be able to tell the difference between cells or substances that are “self” (part of you) and “non-self” (not part of you and possibly harmful). Your body’s cells have proteins on their surfaces or inside them that help the immune system recognize them as “self.”
Some of the proteins that help your immune system recognize “self” cells are called immune checkpoints. Cancer cells sometimes find ways to use these immune checkpoint proteins as shields to avoid being identified and attacked by the immune system.
Immune system cells called T cells roam throughout the body looking for signs of disease or infection. When T cells meet another cell, they analyze certain proteins on the cell’s surface, which helps the T cell identify the cell. If the surface proteins signal that the cell is normal and healthy, the T cell leaves it alone. If the surface proteins suggest the cell is cancerous or unhealthy in another way, the T cell starts an attack against it. Once T cells start an attack, the immune system begins to make more specialized proteins that prevent this attack from damaging normal cells and tissues in the body. These specialized proteins that keep healthy cells and tissues safe are called immune checkpoints.
Immune checkpoint inhibitors target these immune checkpoint proteins and help the immune system recognize and attack cancer cells. Immune checkpoint inhibitors essentially take the brakes off the immune system by blocking checkpoint inhibitor proteins on cancer cells or on the T cells that respond to them.
For example, PD-1 is a checkpoint protein on T cells. PD-L1 is another checkpoint protein found on many healthy cells in the body. When PD-1 binds to PD-L1, it stops T cells from killing a cell. Some cancer cells have a lot of PD-L1 on their surfaces, which stops T cells from killing these cells. Imfinzi stops PD-1 from binding to PD-L1 and allows T cells to attack the cancer cells.
Imfinzi is currently approved to treat certain types of non-small cell lung cancer and small cell lung cancer.
Imfinzi is not currently approved to treat breast cancer. But because Keytruda has been effective against triple-negative breast cancer, researchers want to know if Imfinzi could be another possible treatment.
About the study
Earlier results from the study suggested that adding Imfinzi to neoadjuvant chemotherapy could improve outcomes for women diagnosed with early-stage, triple-negative breast cancer. But the women in the study didn’t reflect the racial or ethnic makeup of women diagnosed with triple-negative breast cancer. In this small study, the researchers wanted to see if the effectiveness of Imfinzi was different between Black women and women of other races and ethnicities. So, even though the study was already underway, the researchers recruited more Black women to join.
This analysis included 67 women diagnosed with early-stage, triple-negative breast cancer:
21 women were Black
40 were white
three were Hispanic or Latina
three were Asian
The women ranged in age from 27 to 79.
To see how effective Imfinzi was, the researchers measured:
pathologic complete response (pCR)
three-year overall survival
One way that doctors judge the effectiveness of neoadjuvant treatments is to look at the tissue removed during surgery to see if any actively growing cancer cells are present. If no active cancer cells are present, doctors call it a pathologic complete response, or pCR. Several studies have shown an association between pCR after neoadjuvant chemotherapy for breast cancer and better overall survival.
Overall survival is how long someone lives, whether or not the cancer recurs. Event-free survival is how long someone lives without the cancer growing or recurring.
pCR rates were:
43% for Black women
48% for the other women
Estimated three-year overall survival rates were:
81% for Black women
87% for the other women
Three-year event-free survival rates were:
71.4% for Black women
78.3% for the other women
The differences in pCR, overall survival, and event-free survival rates were not statistically significant, which means they could have happened by chance and weren’t because the women were of different races or ethnicities.
No matter their race or ethnicity, women who had a pCR had longer event-free survival and better overall survival than women who didn’t have a pCR.
Overall rates of side effects were also similar in Black women and women of other races:
38% of Black women had a side effect of any grade
39% of the other women had a side effect of any grade
Rates of serious side effects — grade 3 or higher — that led some of the women to stop treatment for a time or receive steroids, also were similar for everyone in the study:
24% of Black women had a serious side effect
20% of the other women had a serious side effect
“The low accrual of ethnic minorities, particularly Black Americans, in clinical trials is problematic for several reasons,” senior author Lajos Pusztai, MD, DPhil, professor of medicine and co-director of the Center for Breast Cancer in the Yale Cancer Center at the Yale School of Medicine, said in a statement. “For one, it means Black patients are not given equitable access to potentially lifesaving new treatments very early on. Secondly, it limits our ability to study potential differences in drug metabolism, toxicity, and efficacy between populations with different ancestries.
“Our study demonstrates that if patients are given similar treatment and similar follow-up, the differences in outcomes between Black and non-Black patients are reduced,” Dr. Pusztai continued. “By improving healthcare access and delivery, we could mitigate some of the healthcare disparities that exist in our society.”
What this means for you
If you’re a Black woman who’s been diagnosed with early-stage, triple-negative breast cancer, the results of this study are reassuring. Although the study is small, about a third of the women in the study were Black. And the results showed that:
Imfinzi was just as effective in Black women as it was in women of other races and ethnicities
the rates of side effects also were similar for Black women and women of other races and ethnicities
It’s important to know that you can help bring about change in breast cancer research. By being your own advocate and asking your doctor to recommend clinical trials that are a good fit for your situation, you can start to transform clinical trial participation.
Nadine Barrett, PhD, founding director of the Office of Health Equity and Disparities at the Duke Cancer Institute, joined the Breastcancer.org Podcast to discuss how the Just Ask program is increasing diversity in clinical trials.
Learn more about Clinical Trials.
Written by: Jamie DePolo, senior editor
— Last updated on September 20, 2022, 9:34 PM