“Scientists are stepping up the hunt for better diagnostic tests to predict if cancer patients will benefit from costly modern immunotherapy drugs, which are transforming cancer care but remain a hit-and-miss affair.
“Research presented at Europe’s biggest oncology congress in Madrid adds to evidence that patients with an above average number of genetic mutations in their tumors have a better chance of responding to the new treatments, and drugmakers are racing to confirm the idea.”
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.