Immunotherapy shows promise vs. breast cancer

IMMUNOTHERAPY has potential as a possible treatment option for patients with the difficult-to-treat triple negative breast cancer mutation, says a study from Mayo Clinic, in conjunction with Caris Life Sciences, which was presented this week at the 50th annual meeting of the American Society of Clinical Oncology in Chicago.

Triple negative breast cancer is an aggressive form of breast cancer that evades the immune system because it lacks expression of genes for estrogen receptor, progesterone receptor and HER2.

“This study may change our ability to treat triple negative breast cancer patients,” says Barbara Pockaj, M.D., lead investigator of the study and Mayo Clinic surgeon. “We may have signs that these patients can be treated with immunotherapy. We don’t have a lot of options for these patients and this would really expand our options.”
Dr. Pockaj and her colleagues examined biomarkers involved in immune evasion including the gene PD-L1 and its association with other biological pathways as potential treatment options. In other cancers, such as melanoma, renal cell carcinoma and even lung cancer, patients who have the PD-L1 gene have been treated with immunotherapy – enhancing the body’s immune system – and some of the results have been dramatic, she says.
“This is important because immunotherapy is evolving as an effective treatment for patients with cancer,” she says. “The question is, ‘Can we expand this type of treatment to patients with breast cancer?’”
The study analyzed 511 triple negative breast cancer samples using a multiplatform approach, including whole genome mRNA expression, protein expression, gene copy number changes and gene sequencing. Of the samples, 25 to 30 percent had the PD-L1 gene, which means those patients may be candidates for immunotherapy.

While the results need further investigation, they illustrate how molecular profiling can be used to identify potential treatment targets in triple negative breast cancer and other difficult-to-treat cancers.
“We now want to do validation studies in which we would hope to determine whether those patients who overexpress PD-L1 also have changes in their DNA repair genes,” Dr. Pockaj says. “And if they have both, it suggests the combination immunotherapy and chemotherapy may work.”