The toxicity and efficacy of donor lymphocyte infusions given after reduced-intensity conditioning allogeneic stem cell transplantation.

We describe the toxicity and efficacy of donor lymphocyte infusions (DLIs) given to 81 patients (median age, 50 years) after reduced-intensity conditioning (RIC) transplantations performed at 16 centers in the United Kingdom. The diseases treated included non-Hodgkin lymphoma (NHL; n = 29), chronic myeloid leukemia (CML; n = 12), myeloma (n = 11), acute myeloid leukemia (AML; n = 10), and chronic lymphocytic leukemia (CLL; n = 9). Eighty-eight percent received stem cells from sibling donors. The patients received 130 infusions (median, 1; range, 1-4). Indications for DLI were unsatisfactory response/disease progression in 51 patients, mixed chimerism in 18, preemptive in 10, and other in 2. Graft hypoplasia was uncommon (11%). Grade II to IV graft-versus-host disease (GVHD) occurred in 23 of 81 patients (28%) and limited and extensive chronic GVHD in 5 of 69 and 18 of 69 evaluable patients (total incidence 33%). Conversion from mixed to full donor chimerism occurred in 19 of 55 evaluable patients (35%) at a median of 48 days after the DLI; partial responses occurred in 6 patients (total response rate 45%). Eighteen of 51 (35%) patients with measurable disease after stem cell transplantation had a complete response (2 molecular), and 5 a partial response (total response rate 45%). Eleven of 17 evaluable complete responders had full donor chimerism. Eight of 13 patients with follicular NHL had complete responses as did 4 of 12 patients with CML. Clinical and chimeric responses correlated strongly with acute and chronic GVHD. Forty-seven patients (58%) survive at a median of 508 days after transplantation (range, 155-1171 days) with a median Karnofsky score of 90. Thirty-four patients (42%) died at a median of 211 days after transplantation with the major causes being progressive disease (26%) and GVHD (9%). Further systematic studies are required to determine the efficacy and optimum use of DLI for patients with each disease treated by nonmyeloablative stem cell transplantation.