Durable responses after donor lymphocyte infusion for patients with residual multiple myeloma following non-myeloablative allogeneic stem cell transplant

The role of donor lymphocyte infusion (DLI) in mediating the graft-versus-myeloma (GvM) effect after allogeneic hematopoietic stem cell transplant (allo-HCT) is not clearly defined. We evaluated the safety and utility of DLI in patients with either persistent or recurrent multiple myeloma (MM) after allo-HCT. Twenty-three patients with MM received DLI after allo-HCT at the University of Texas M. D. Anderson Cancer Center between July 1996 and June 2008. Eight patients received preemptive DLI for residual disease (RD) while 15 patients received DLI for the treatment of recurrent or progressive disease (PD). We evaluated the response to DLI and the factors that may predict a response. Median DLI dose was 3.3 × 10⁷ CD3 cells (range 0.5-14.8 × 10⁷). Grade II-IV acute graft-versus-host disease (GvHD) was seen in five patients (22%). Median follow-up in surviving patients was 24 months. Five of 23 patients (22%) achieved a complete or a very good partial response (two CR, three VGPR), while eight patients (34%) had stable disease (SD) after the DLI. Patients who received DLI for RD had a higher response rate (≥ VGPR 50% vs. 7%, p = 0.03), a longer overall survival (28.3 vs. 7.6 months, p = 0.03) and a trend toward longer progression-free survival (11.9 vs. 5.2 months, p = 0.1). In this largest single institution study, we conclude that the use of preemptive, non-manipulated DLI for RD after reduced-intensity conditioning allo-HCT is encouraging, and it was associated with a higher response rate and a longer overall survival when given preemptively. The role of DLI needs to be further explored in prospective clinical trials.