Allogeneic hematopoietic cell transplantation from unrelated donors in multiple myeloma: study from the Italian Bone Marrow Donor Registry.

To evaluate trends in allografting from unrelated donors, we conducted a study on 196 consecutive myeloma patients transplanted between 2000 and 2009 in Italy. Twenty-eight percent, 37%, and 35%, respectively, received myeloablative, reduced-intensity, and nonmyeloablative conditioning. In these 3 cohorts, 1-year and 5-year transplantation-related mortalities were 28.8% and 37.0%, 20.3% and 31.3%, and 25.0% and 30.3%, respectively (P = .745). Median overall survival (OS) and event-free survival from transplantation for the 3 cohorts were 29 and 10 months, 11 and 6 months, and 32 and 13 months, respectively (P = .039 and P = .049). Overall cumulative incidences of acute and chronic graft-versus-host-disease (GVHD) were 46.1% and 51.1%. By Cox multivariate analyses, chronic GVHD was significantly associated with longer OS (hazard ratio [HR], .51; P = .009), whereas the use of peripheral blood stem cells was borderline significant (HR, .55; P = .051). Better response posttransplantation was associated with longer event-free survival (HR, 2.13 to 4.25; P < .001). Acute GVHD was associated with poorer OS (HR, 2.53; P = .001). This analysis showed a strong association of acute and chronic GVHD and depth of response posttransplantation with clinical outcomes. Long-term disease control remains challenging regardless of the conditioning. In the light of these results, prospective trials may be designed to better define the role of allografting from unrelated donors in myeloma.