Today at the annual meeting of the European Society for Medical Oncology, an international team of breast cancer experts reported findings from a large clinical trial. They had tested a combination of immunotherapy and chemotherapy in people with advanced triple-negative breast cancer. The investigators found that many people in the study who had the immunotherapy combination therapy lived longer compared with chemotherapy alone.
Memorial Sloan Kettering medical oncologists Elizabeth Comen and Christopher Klebanoff, both experts in breast cancer immunotherapy, offer their perspective about these findings and the potential impact on the field. Neither Dr. Comen nor Dr. Klebanoff were part of the study, which is being published in the New England Journal of Medicine.
“Immunotherapy works best on solid tumors that have large numbers of mutations because mutations put up flags that make the tumors visible to the immune system,” explained Dr. Comen. “It’s long been thought that triple-negative breast cancers might be susceptible to immunotherapy because they tend to have a lot more mutations that the immune system can recognize.”
The trial included 902 people who were treated at 246 hospitals in 41 countries. All of them had locally advanced or metastatic triple-negative breast cancer. The people in this study were given either a standard chemotherapy drug for this type of breast cancer called nab-paclitaxel (Abraxane®); an immunotherapy drug already approved for other cancers called atezolizumab (Tecentriq®), which works against the protein PD-L1; or a combination of the two.
The researchers reported that people with tumors that expressed the PD-L1 protein who received the combination therapy lived 9.5 months longer. About 41% of people in the trial had this protein on their tumors. “This is not a cure, and at every step of the way we’re always looking for that,” Dr. Comen says. “But any incremental benefit to patients’ lives can be significant, and this is a significant benefit.”
“There is a tremendous unmet medical need in this breast cancer subtype,” Dr. Klebanoff says. “We’ve made great progress in recent years in treating other types of breast cancer, but triple-negative breast cancer has not benefitted from many advances. This study dispels the myth that immunotherapy cannot work for breast cancer. As we learn more about this approach, we expect to see more and better treatment options for many breast cancer patients.”