Phase I trial of iodine-131 tositumomab with high-dose chemotherapy and autologous stem-cell transplantation for relapsed non-Hodgkin's lymphoma.

Objective: To determine the maximum outpatient dose of iodine-131 tositumomab (up to 0.75 Gy) combined with high-dose carmustine, etoposide, cytarabine, and melphalan (BEAM) followed by autologous stem-cell transplantation (ASCT) for the treatment of chemotherapy-resistant relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL).

Methods: Twenty-three patients with chemotherapy-refractory or multiply-relapsed B-cell NHL were treated in a phase I trial combining iodine-131 tositumomab (ranging from 0.30 to 0.75 Gy total-body dose [TBD]) with high-dose BEAM followed by ASCT.

Results: The complete response rate after transplantation was 57%, and the overall response rate was 65%. Short-term and long-term toxicities were similar to historical control patients treated with BEAM alone. With a median follow-up of 38 months (range, 27 to 60 months), the overall survival (OS) rate was 55%, and the event-free survival (EFS) rate was 39%.

Conclusions: There were no significant added toxicities apparent with the addition of iodine-131 tositumomab up to a dose of 0.75 Gy TBD to high-dose BEAM chemotherapy followed by ASCT. The EFS and OS were encouraging in this group of chemotherapy-resistant or refractory B-cell NHL patients. A follow-up phase II trial with iodine-131 tositumomab at the dose of 0.75 Gy TBD with BEAM is currently ongoing.