In a phase 2 clinical trial of the immune checkpoint inhibitor pembrolizumab, investigators found that 42 percent of patients with metastatic brain cancer benefited from the therapy, with seven patients in the trial surviving longer than two years. "There are very few effective treatments for patients with brain metastases. Our overarching objective is to find improved therapies for this patient population," said Priscilla K. Brastianos, MD. "With this trial, we investigated pembrolizumab, which is an immunotherapy for patients with brain metastases. We showed that pembrolizumab was tolerated and showed clinical benefit in the brain in 42 percent of patients, which...