Purpose

This is a study of pembrolizumab (MK-3475) for participants with relapsed/refractory classical Hodgkin Lymphoma (RRcHL) who: 1) have failed to achieve a response or progressed after autologous stem cell transplant (auto-SCT) and have relapsed after treatment with or failed to respond to brentuximab vedotin (BV) post auto-SCT or 2) were unable to achieve a Complete Response (CR) or Partial Response (PR) to salvage chemotherapy and did not receive auto-SCT, but have relapsed after treatment with or failed to respond to BV or 3) have failed to achieve a response to or progressed after auto-SCT and have not received BV post auto-SCT. The primary study hypothesis is that treatment with single agent pembrolizumab will result in a clinically meaningful overall response rate.