We report here on a patient with metastatic melanoma who had extensive brain metastases. After being treated with the sequential combination of whole brain radiation therapy (WBRT) followed by the PD-1 inhibitory antibody, pembrolizumab, the patient had a durable complete response. Retrospective laboratory studies of T cells revealed that, after treatment with anti-PD-1 commenced, effector CD8+ T cells in the blood expanded and the ratio of CD8+:Treg T cells increased. A CD8+ T-cell clone present in the initial brain metastases was expanded in the blood after anti-PD-1 treatment, which suggested an antitumor role for this clone. Immunohistochemistry analysis confirmed the presence of CD8+ T cells and low PD-L1 expression in the brain metastases before immunotherapy initiation. This sequence of therapy may provide an option for melanoma patients with unresponsive brain metastases.
- Received August 31, 2016.
- Revision received November 29, 2016.
- Accepted December 9, 2016.
- Copyright ©2017, American Association for Cancer Research.