Introduction: High relapse rates and infections remain primary causes of failure in nonmyeloablative transplantation. Interleukin-2 (IL-2) may stimulate the immune system and improve outcomes. The primary objective of this pilot study was to evaluate the feasibility of administering IL-2 following a T-cell-depleted nonmyeloablative hematopoietic stem cell transplant.
Methods: Patients received T-cell-depleted nonmyeloablative transplant from a matched or mismatched related donor. Those with allogeneic engraftment, <grade 2 acute GVHD at time of study entry, and no severe end organ damage were eligible and received IL-2 starting 6 weeks after the first day of stem cell infusion. Patients received 1 mu/m2 daily for 5 days each week for 4 weeks followed by a 2-week rest period for a 6-week cycle to continue for up to 1 year.
Results: Eight patients aged 28-69 years were treated. Significant toxicities were limited to GVHD of the skin ≤grade 2 in 3 patients and severe fatigue in 4 patients, limiting the duration of therapy. Two of the 8 patients died of relapsed disease and 1 from CMV. With a median overall duration of follow-up of survivors of 48 months, 5 patients (63%) remain alive and in continuous complete remission.