The standard or usual treatment for this disease is pembrolizumab given by needle every three weeks. This study will be done in two stages.~The purpose of stage 1 of the study is to find out if we can use blood tests to see how the cancer is responding to treatment with pembrolizumab. A second stage of the study will take place once stage 1 is completed. In stage 2 blood tests will be used to help determine if patients whose cancer does not seem to be getting better on treatment with pembrolizumab, would do better on a different treatment.
The purpose of stage 1 of the study is to find out if blood tests can be used to see how the cancer is responding to treatment with pembrolizumab.