Donor lymphocyte infusions for relapsed multiple myeloma after allogeneic stem-cell transplantation: predictive factors for response and long-term outcome.

PURPOSE: To determine the efficacy, toxicity, and long-term outcome and prognostic factors of donor lymphocyte infusions (DLI) in patients with relapsed multiple myeloma (MM) after allogeneic stem-cell transplantation (AlloSCT).

MATERIALS AND METHODS: Twenty-seven patients received 52 DLI courses at a median of 30 months after the previous AlloSCT. Reinduction therapy was administered to 13 patients before DLI.

RESULTS: Reinduction therapy was successful in eight of 13 patients. Fourteen patients (52%) responded to DLI, including six patients (22%) who achieved a complete remission (CR). Five patients responded after T-cell dose escalation in subsequent DLIs. Four patients experienced relapse or disease progression (three from partial response and one from CR). Five patients remain in remission more than 30 months after DLI. Major toxicity was acute and chronic graft-versus-host disease (GVHD), which was present in 55% and 26% of patients, respectively. Two patients died from bone marrow aplasia. Median overall survival of all patients was 18 months. Overall survival was 11 months for DLI-resistant patients and has not been reached for the responding patients. In two patients, sustained molecular remission was observed. The factors that were correlated with response to DLI were a T-cell dose of more than 1.10(8) cells/kg, response to reinduction therapy, and chemotherapy-sensitive disease before AlloSCT.

CONCLUSION: These data confirm the potential and durable graft-versus-myeloma effect of DLI in patients with relapsed MM after AlloSCT. Future studies should be aimed at increasing response rates, especially in patients with chemoresistant disease, and reducing toxicity by limiting GVHD. Adjuvant DLI seems an attractive and promising approach for patients who do not achieve a molecular remission after AlloSCT.