Donor Lymphocyte Infusion to Enhance the Graft-versus-Myeloma Effect

Donor lymphocyte infusion (DLI) has the potential to significantly deepen the response after allogeneic stem cell transplantation (ASCT) in multiple myeloma (MM). Subsequently, DLI offers the opportunity for long-term progression-free and, most importantly, overall survival for patients with MM. DLI application is a complex procedure, whereby many factors need to be considered (e.g., patient-oriented factors prior to application, disease-specific factors, as well as possible combinations with further therapies during and after DLI). There are two settings in which DLI can be given, they are as follows: as a salvage option in progressive disease or in the prophylactic setting for MM patients with resolved disease to further deepen the response. While the first studies used DLI in the salvage setting, results for prophylactic DLI appear to be associated with better and prolonged outcomes. Furthermore, DLI (both prophylactic and salvage) given earlier after ASCT (3-6 months) appear to be associated with better outcomes. The incorporation of novel agents showed similar responses and survival after DLI. However, updated and larger evaluations are urgently needed to determine the specific role of multiple variables in such a complex treatment environment of ASCT in an ever-evolving field of MM. This review underlines the rationale for DLI after ASCT, results in the salvage and prophylactic settings, patterns of disease progression after DLI, as well as avenues to further enhance the graft-versus-myeloma effect exerted by DLI.