Purpose: Donor leukocyte infusion (DLI) effectively treats relapse after allogeneic stem-cell transplantation (alloSCT), but the response may require several months and may be associated with significant toxicity. Filgrastim has also been observed to effectively treat leukemic relapse after alloSCT. A retrospective analysis was performed to determine the effectiveness of filgrastim in treating relapses after alloSCT.
Patients and methods: Fourteen patients with hematologic malignancies were treated with filgrastim at relapse after alloSCT. Filgrastim was given at 5 mcg/kg/d subcutaneously for 21 consecutive days. Response was evaluated at 7 days after completion of filgrastim. Immunosuppressants, if present, were rapidly tapered to complete discontinuation at the time of relapse.
Results: Three patients were not assessable for response because additional therapy was necessary before completion of filgrastim. Six patients (43%) achieved a complete response on an intent-to-treat basis. When response was evaluated based on relapse type, three of four cytogenetic relapses, two of three morphologic relapses, and one of four hematologic relapses achieved a complete remission. Two responses were observed in patients who were completely off of any immunosuppression at the time of relapse. Six patients developed chronic graft-versus-host disease. The event-free and overall survival rates for all 14 patients are 43% and 73%, respectively.
Conclusion: The use of filgrastim with rapid discontinuation of immunosuppression results in response rates that are similar to results using DLI. Filgrastim could be considered as an alternative or an adjunct to DLI for relapses after alloSCT.