Emerging role of novel therapies in Hodgkin lymphoma: proceed with caution.

Based on very high response rates in the relapsed and refractory setting, brentuximab vedotin and the programmed cell death protein 1 (PD-1) inhibitors, nivolumab and pembrolizumab, have quickly been incorporated into clinical trials for first- and second-line therapy of Hodgkin lymphoma. Preliminary data show that brentuximab vedotin alone is not adequate therapy for newly diagnosed Hodgkin lymphoma in older patients, but modestly decreases the risk of relapse when combined with adriamycin, vinblastine, and dacarbazine in patients with previously untreated advanced-stage disease. In second-line therapy, combining brentuximab vedotin with conventional chemotherapy or with PD-1 inhibitors as pretransplant salvage is associated with high overall and complete response rates, although further follow up is needed to assess whether posttransplant outcomes are improved. Although these new drugs are well tolerated when given as single agents, unexpected toxicities have been encountered with combination regimens, specifically severe pulmonary toxicity with the bleomycin and brentuximab vedotin combination and frequent infusion-related reactions. There is concern with the use of PD-1 inhibitors as first-line therapy due to the theoretical potential for more frequent or severe immune-mediated toxicities in patients who have not received prior chemotherapy. Aside from these concerns, these new agents have the potential to improve outcomes for patients even further, bringing us closer to eradicating recurrent Hodgkin lymphoma.