A pilot study evaluating interleukin-2-activated hematopoietic stem cell transplantation for hematologic malignancies.

Cytotoxic effector cells are generated when autologous hematopoietic cells (HSC) are cultured with IL-2 for 24 h. Infusion of these cells followed by IL-2 administration may moderate a graft-versus tumor (GvT) effect in vivo. Sixteen patients--7 with non-Hodgkin's lymphoma (NHL), 2 with AML, 4 with multiple myeloma (MM), and 3 with Hodgkin's disease (HD)--received busulfan (4 mg/kg/day for 4 days) and cyclophosphamide (60 mg/kg/day for 2 days) or cyclophosphamide/TBI (1320 cGy). Autologous HSC were activated by culturing with IL-2 for 24 h before reinfusion. Subcutaneous administration of IL-2 began after engraftment at 1.8 x 10(6) IU/m2/day for 1-4 weeks. Neutrophil engraftment occurred on day 13.1 (median) (range 9-45 days), and platelet engraftment occurred on day 19.3 (median) (range 7-54 days) for 15 patients, with delayed engraftment observed in 3 patients. One patient experienced a fatal cardiac arrhythmia. Five patients developed transient skin rashes with histologic evaluation demonstrating findings consistent with GvHD. At 17 months (median) (range 7-23 months), 9 patients are alive, with 6 patients remaining disease free. This pilot trial demonstrates mild to moderate toxicities and a possible delay in platelet engraftment. Further trials will determine the optimal dose and duration of IL-2 therapy and possible impact of this therapy on survival. Laboratory investigations are evaluating the presence of autologous GvHD and a possible GvT effect.