Blood Assay Predicts Response to Pembrolizumab.

Researchers found that the magnitude of reinvigoration of CD8+ T cells-the peak level of Ki67 after treatment-compared with tumor burden prior to treatment with the PD-1 inhibitor pembrolizumab correlated with clinical response in patients with advanced melanoma. If this finding is confirmed in a larger cohort of patients, the ratio of these two factors could be used to determine whether a patient should continue with pembrolizumab therapy or switch to a different treatment or combination of treatments.