Outcome of autologous hematopoietic stem cell transplantation in refractory multiple myeloma

Background Despite the introduction of effective, novel agents, the outcome of patients with refractory multiple myeloma remains poor, particularly those who are refractory to both proteasome inhibitors (PIs) and immunomodulatory agents (IMiDs). Limited data are available on the role of autologous hematopoietic stem cell transplantation in this population. Methods Patients with refractory myeloma who underwent first autologous hematopoietic stem cell transplantation (auto-HCT) between March 2000 and October 2015 were retrospectively analyzed. Those who had primary refractory disease and those with relapsed and refractory disease were included. Disease that was refractory to at least 1 PI and at least 1 IMiD was classified as double-refractory multiple myeloma (DR-MM). Results In total, 233 patients were identified, including 105 (45%) classified with DR-MM and 128 (55%) classified with nondouble-refractory myeloma (NDR-MM). At a median follow-up of 42 months for surviving patients, at least a partial response was observed in 188 patients (81%; 83 patients in the DR-MM group [79%] and 105 patients in the NDR-MM [82%]; P = .77). A near complete response or better was observed in 52 patients (22%; 25 patients in the DR-MM group [24%] and 27 patients in the NDR-MM group [21%]; P = .77). The median progression-free survival was 17.6 months (14.4 months in the DR-MM group and 18.2 months in the NDR-MM group), and the 2-year progression-free survival rate was 38% (35% in the DR-MM group and 40% in the NDR-MM group; P = .40). The median overall survival was 48 months (38.9 months in the DR-MM group and 56.6 months in the NDR-MM group), and the 2-year overall survival rate was 74% (71% in the DR-MM group and 76% in the NDR-MM group; P = .27). Conclusions The current findings indicate that auto-HCT is an effective and safe therapy in patients with refractory multiple myeloma, including those who are refractory to IMiDs and PIs. Cancer 2017;123:3568-75. © 2017 American Cancer Society.