A Phase 1b/2 trial of mapatumumab in patients with relapsed/refractory non-Hodgkin's lymphoma

BACKGROUND: We conducted a multicentre Phase 1b/2 trial to evaluate the safety and efficacy of mapatumumab, a fully human agonistic monoclonal antibody to the tumour necrosis factor-related apoptosis-inducing ligand receptor 1 (TRAIL-R1) in patients with relapsed non-Hodgkin's lymphoma (NHL). METHODS: Forty patients with relapsed or refractory NHL were treated with either 3 or 10 mg kg(−1) mapatumumab every 21 days. In the absence of disease progression or prohibitive toxicity, patients received a maximum of six doses. RESULTS: Mapatumumab was well tolerated, with no patients experiencing drug-related hepatic or other dose-limiting toxicity. Three patients with follicular lymphoma (FL) experienced clinical responses, including two with a complete response and one with a partial response. Immunohistochemistry staining of the TRAIL-R1 suggested that strong staining in tumour specimens did not appear to be a requirement for mapatumumab activity in FL. CONCLUSIONS: Mapatumumab is safe and has promising clinical activity in patients with FL.