“The combination of immunotherapy and chemotherapy is showing promising response rates in certain patients with triple-negative breast cancer (TNBC), said ESO Umberto Veronesi Memorial Award Winner Giuseppe Curigliano, MD, PhD, who addressed genetic determinants of breast cancer immunogenicity in his award lecture at the 15th St. Gallen International Breast Cancer Conference.
“Curigliano emphasized the importance of patient selection in optimizing immunotherapy in breast cancer. In a study done by Curigliano, in collaboration with the Sidra Medical Center in Qatar, a subgroup of patients with TNBC who would derive benefit from checkpoint inhibitors were identified. This group, he stated, should be selected based on individual assessment of tumor-infiltrating lymphocytes.”
“Despite breast tumors’ lower mutational loads than lung cancers and melanoma—cancers in which immunotherapy have shown particular promise—breast cancers are nevertheless immunogenic, Elizabeth A. Mittendorf, MD, PhD, of the University of Texas MD Anderson Cancer Center in Houston, reported at the 34th Annual Miami Breast Cancer Conference, held March 9–12 in Miami Beach, Florida.
“Multiple clinical trials are now underway to evaluate immunotherapy strategies in breast cancer, Mittendorf noted.
“Combination immunotherapy regimens are ‘likely the way forward’ and appropriate combinatorial strategies will hinge importantly on disease stage, she said.”
TNBC has long been considered to be more amenable to immune system-based treatments than other types of breast cancer because it is more immunogenic; that is, relatively high levels of immune cells accumulate within or adjacent to TNBC tumors. These immune cells could be triggered to attack tumors if properly activated. TNBC tumors are also likely to have a higher mutational burden (number of genetic mutations). This is one of the predictors of sensitivity to a type of treatment called immune checkpoint blockade. Drugs known as checkpoint inhibitors block the proteins PD-1 or PD-L1. In cancer, PD-L1 proteins on tumor cells bind to PD-1 proteins on immune T cells and inhibit their tumor-killing activity. Immune checkpoint drugs disable this interaction and enable activation of T cells. These drugs are actively being explored in TNBC in clinical trials.