Source: EurekAlert!, April 2017
PHILADELPHIA — Despite the success of immunotherapies based on blocking the programmed cell death 1 (PD-1) receptor protein in metastatic melanoma patients, more than half do not experience a lasting benefit by seeing their tumors shrink. One possible reason the drug doesn’t work well for all patients is that these PD-1 blocking drugs lack a biological effect in many patients. However, new studies now indicate that 80 percent of these patients do, in fact, have an increase in the number of responding T cells to these types of treatments. The PD-1-targeting antibody pembrolizumab is a checkpoint inhibitor drug that takes the brake off the PD-1 receptor to allow T cells to replicate and react more strongly to cancer cells.
But why the considerable disconnect between shrinking tumors and ballooning T cell numbers in this patient population? A new study published in Nature provides clues that could enhance physicians’ ability to pinpoint, in real-time, which patients are not responding to therapy – and intervene with additional drugs to boost the chances of shrinking tumors. The paper is the first major publication to come out of the Parker Institute for Cancer Immunotherapy research collaborative.read the original full article