Adding the immunotherapy medicine Tecentriq (chemical name: atezolizumab) to chemotherapy before surgery for early-stage triple-negative breast cancer offered higher pathologic complete response (pCR) rates than chemotherapy alone, no matter the PD-L1 status of the cancer, according to results from the IMpassion031 study.
The research was presented on Sept. 20, 2020, at the European Society for Medical Oncology (ESMO) Virtual Congress 2020 and published on the same day by The Lancet.
- Read the ESMO 2020 abstract of “IMpassion031: Results from a phase III study of neoadjuvant (neoadj) atezolizumab + chemotherapy in early triple-negative breast cancer (TNBC).”
- Read The Lancet abstract of “Neoadjuvant atezolizumab in combination with sequential nab-paclitaxel and anthracycline-based chemotherapy versus placebo and chemotherapy in patients with early-stage triple-negative breast cancer (IMpassion031): a randomised, double-blind, phase 3 trial.”
Triple-negative breast cancer is cancer that has no receptors for the hormones estrogen and progesterone, as well as no receptors for the HER2 protein. This limits the medicines that can be used to treat the cancer.
Doctors call treatments given before surgery neoadjuvant treatments.
What is pCR?
One way 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 disease-free survival, as well as better overall survival.
Disease-free survival is how long a person lives without the breast cancer coming back. Overall survival is how long a person lives, with or without the breast cancer coming back.
Tecentriq is an immune checkpoint inhibitor.
To start an immune system 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) vs. “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 these 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 a shield 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.
Immune checkpoint inhibitors target 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.
PD-1 is a type of checkpoint protein found 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 surface, which stops T cells from killing these cancer cells. An immune checkpoint inhibitor medicine that stops PD-1 from binding to PD-L1 allows T cells to attack the cancer cells.
Tecentriq is a PD-L1 inhibitor approved by the U.S. Food and Drug Administration to be used in combination with the chemotherapy medicine Abraxane (chemical name: albumin-bound or nab-paclitaxel) to treat unresectable locally advanced or metastatic triple-negative, PD-L1-positive breast cancer.
Tecentriq is given intravenously, which means the medicine is delivered directly into your bloodstream through an IV or a port.
The IMpassion031 study
The IMpassion031 study included 333 women diagnosed with stage II or stage III triple-negative breast cancer. None of the women had been treated for breast cancer yet.
Selected characteristics of the women in the study:
- their ages ranged from 22 to 78
- about 46% were diagnosed with PD-L1-positive triple-negative disease
- about 63% were white, 26% were Asian, and 7% were Black
- about 77% had been diagnosed with stage II disease
The women were assigned to one of two treatments before breast cancer surgery:
- Tecentriq plus Abraxane, followed by Adriamycin (chemical name: doxorubicin) and Cytoxan (chemical name: cyclophosphamide) (165 women)
- placebo (an infusion that looked just like Tecentriq, but contained no medicine) plus Abraxane, followed by Adriamycin and Cytoxan (168 women)
Researchers followed the women for 20 months.
After chemotherapy was completed, all the women had surgery and the researchers measured pCR rates.
Overall, pCR rates were:
- 57.6% for women treated with Tecentriq plus chemotherapy
- 41.1% for women treated with chemotherapy alone
This difference was statistically significant, which means that it was likely due to the difference in treatment and not just because of chance.
For women diagnosed with PD-L1-positive triple-negative breast cancer, pCR rates were:
- 68.8% for women treated with Tecentriq plus chemotherapy
- 49.3% for women treated with chemotherapy alone
This difference was not statistically significant.
“The combination of atezolizumab with neoadjuvant chemotherapy for stage II to III triple-negative breast cancer provides clinically meaningful pCR benefit with an acceptable safety profile independent of PD-L1 status,” said senior study author Nadia Harbeck, M.D., Ph.D., head of the Breast Center at the University of Munich, during her presentation. “This new combination therapy may offer an improved curative treatment option for this patient population with a high unmet medical need.”
Tecentriq side effects
Like almost all cancer medicines, Tecentriq can cause side effects, some of them severe.
In the IMpassion031 study, the most common side effects seen in women treated with Tecentriq were:
- hair loss
- low red blood cell counts
More women treated with Tecentriq had severe side effects compared to women treated with chemotherapy alone:
- 22.6% of women treated with Tecentriq and chemotherapy had a severe side effect
- 15.6% of women treated with chemotherapy alone had a severe side effect
The most common severe side effects were:
- infection caused by low white blood cell counts
About 23% of the women treated with Tecentriq plus chemotherapy and about 20% of the women treated with chemotherapy alone stopped treatment because of side effects.
What this means for you
If you’ve been diagnosed with early-stage triple-negative breast cancer, the results of the IMpassion031 study are very promising.
Still, it’s important to know that these are early results. The study is ongoing and will look to see if the higher pCR rates in women treated with Tecentriq will lead to better progression-free survival, as well as better overall survival.
Right now, Tecentriq is not approved to treat early-stage breast cancer. If you’re interested in exploring Tecentriq treatment options, you may want to talk to your doctor about enrolling in a clinical trial using Tecentriq to treat early-stage triple-negative disease.
For more information on immunotherapy medicines, how they work, and their possible side effects, visit the Breastcancer.org Immunotherapy section.
To discuss immunotherapy options with others, join the Breastcancer.org Discussion Board forum Immunotherapy – Before, During, and After.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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