Background: Relapse of non-Hodgkin's lymphoma (NHL) remains a problem after autologous stem cell transplantation (ASCT). Soon after ASCT, the immune system is not very active, and this immune incompetence could thus result in decreased ability for immune-mediated tumor eradication. The early addition of immunotherapy after ASCT might decrease the incidence of relapse and prolong survival. In an initial phase I/II trial at our center, the immune modulator interleukin-2 (IL-2) increased over baseline natural killer and lymphokine-activated killer activity in vitro. Because rituximab can lyse CD20-bearing cells by antibody-dependent cellular cytotoxicity, adding IL-2 to rituximab might boost its effectiveness. It thus seemed reasonable to study this combination after ASCT. The results of our phase II study are reported herein.
Patients and methods: Twenty patients with CD20+ NHL who had ASCT were treated. The median time to starting therapy was 79 days (range, 49-100 days) after transplantation.
Results: The majority of patients reported grade <or= 2 erythema, induration and pain at IL-2 injection sites, flu-like symptoms, and worsening fatigue. Neutropenia that responded to granulocyte colony-stimulating factor was the most common grade 3/4 toxicity, seen in 45% of patients. There were no treatment-related deaths. Eighteen of 20 patients remain alive in complete remission, with a median follow-up of 55.5 months (range, 17-64 months).
Conclusion: Interleukin-2/rituximab can be administered after ASCT with manageable toxicity. A randomized trial is under way to address whether this combination therapy is beneficial to patients with NHL who have had ASCT.