Immunotherapy plus Chemotherapy Extends Survival for Patients with Metastatic Triple-Negative Breast Cancer

Triple-negative breast cancer is a type of cancer that doesn’t involve the 3 most common receptors that contribute to breast cancer growth—estrogen, progesterone, and the HER2 gene. Triple-­negative breast cancer is ag­gressive and has poor outcomes, because it has few targeted therapies that have shown benefits.

But finally, a study reported last year at the European Society of Medical Oncology (ESMO) 2018 Congress showed promising results, indicating a real breakthrough in the treatment of this type of cancer that extends survival for patients.

Peter Schmid, MD, PhD, of the Centre for Experimental Cancer Medicine in Barts Cancer Institute in London, England, presented the results of the phase 3 clinical trial known as the IMpassion130 study.

The type of immunotherapies known as checkpoint inhibitors are now being used for many types of solid cancers, but none so far has been approved for patients with metastatic triple-negative breast cancer.

The results from the IMpassion130 study reported by Dr. Schmid demonstrated that adding the checkpoint inhibitor Tecentriq (atezolizumab) to the chemotherapy drug Abraxane (nab-paclitaxel) significantly prolonged the time of survival for patients with advanced or metastatic triple-negative breast cancer. These results will most likely change the way patients with metastatic triple-negative breast cancer are being treated, Dr. Schmid suggests.

Exciting Results

The results showed that adding the immunotherapy Tecentriq to chemotherapy with Abraxane extended by almost 50% the average time of survival without disease progression from 5.5 months with chemotherapy alone to 7.2 months with the addition of immunotherapy.

Furthermore, the results were even better for the smaller group of patients whose breast cancer expressed PD-L1. Tecentriq, a PD-L1 inhibitor, is among several immunotherapies that specifically target cancer that expresses the PD-1 or PD-L1 protein on human cells, which suppresses the activity of T-cells, leading to cancer-­cells growth.

Among the patients with metastatic triple-negative breast cancer and PD-L1 expression, the average length of survival without cancer progression was 7.5 months with the addition of immunotherapy to chemotherapy versus only 5 months with chemotherapy alone.

However, patients are continuing to benefit from the combination of immunotherapy and chemotherapy, indicating that the average survival will be even longer. Indeed, an interim analysis of survival showed that using this combination significantly increased the average overall survival from 17.6 months with chemotherapy alone to 21.3 months in patients who received immunotherapy plus chemo­therapy.

And in the patients with metastatic triple-negative breast cancer and PD-L1 expression, the average overall survival was 25 months compared with only 15.5 months with chemotherapy alone.

“These results will change the way triple-negative breast cancer is treated. Atezolizumab in combination with nab-paclitaxel is the first targeted treatment to improve survival in metastatic triple-negative breast cancer. It is also the first immune therapy to improve outcomes in this cancer,” Dr. Schmid said.

“This combination should become a new treatment option for patients with metastatic triple-negative breast cancer,” he advised.

Dr. Schmid added that focusing on the average time without disease progression in studies related to immunotherapy can be misleading, because treatment with checkpoint inhibitors can lead to durable responses that are not always apparent in the duration of disease-free survival.

“The reduction in progression-free survival or death by 20% in the overall population and by almost 40% in the PD-L1–positive population is a better way to look at the impact of immunotherapy on progression-free survival,” Dr.Schmid stated.

ESMO Expert

ESMO Expert Marleen Kok, MD, PhD, Medical Oncologist at The Netherlands Cancer Institute in Amsterdam, said, “This is the first randomized phase 3 trial providing evidence that adding immunotherapy to standard chemotherapy increases progression-

free survival in metastatic triple-­negative breast cancer, particularly in patients with PD-L1–positive tumors, and extends survival in the PD-L1–positive subgroup.”

“While the benefit in terms of progression-free survival was relatively small, around 3 months, the gain in overall survival in the PD-L1–positive patients was impressive, with a 10-month benefit. The IMpassion130 data will probably change the treatment landscape for our metastatic triple-negative breast cancer patients,” Dr. Kok added.