Pembrolizumab as a bridge to autologous stem cell transplantation in refractory gray zone lymphoma

Abstract

Gray zone lymphoma (GZL), a rare type of B-cell lymphoma (BCL), has features between diffuse large BCL and classical Hodgkin lymphoma (cHL) and an unfavorable outcome. The expression of PD-L1, encoded by chromosome 9p24.1, has been positively correlated with the copy number alteration of 9p24.1, and it has been associated with a high response rate to anti-PD-1 treatment in cHL and primary mediastinal large BCL (PMBCL). GZL shares similar genomic alterations with cHL and PMBCL, and thus, it may also respond well to anti-PD-1 treatment. However, little is known about the efficacy of anti-PD-1 treatment and the predictive role of PD-L1 expression in GZL. Here, we present a case of GZL refractory to first-line chemotherapy. The patient had a high expression of PD-L1 and was successfully treated with pembrolizumab as a salvage treatment, followed by autologous stem cell transplantation (ASCT) in January 2018. The patient still had a complete metabolic response 42 months after ASCT.