Immunotherapy in Hodgkin Lymphoma: The Road Ahead.

An extensive infiltrate of intratumoral immune cells is a hallmark of classic Hodgkin lymphoma (cHL) but these cells do result in an effective antitumor response. Immune checkpoint therapy, which activates 'exhausted' T cells, has been found to be highly effective in cHL, but responding patients commonly relapse. Combination approaches are currently being investigated but the assessment of benefit when adding immunotherapy is challenging. The pitfalls in designing combination studies derive from response endpoints that are difficult to measure, a lack of biomarkers that predict response, and a limited understanding of tumor biology. While progress in treating patients with cHL has been exceptional so far, further progress may require a review of clinical trial endpoints and a greater understanding of cHL biology.