Despite the introduction of effective novel agents, the outcome of patients with refractory multiple myeloma remains poor, particularly those refractory to both proteasome inhibitors (PIs) and immunomodulatory agents (IMiDs). Limited data is available on the role of autologous hematopoietic stem cell transplantation in this population.
We retrospectively analyzed refractory myeloma patients who underwent first auto-HCT between March 2000 and October 2015. Patients with primary refractory disease and those with relapsed and refractory disease were included. Patients with disease refractory to at least one PI and at least one IMiD were classified as double refractory (DR-MM).
233 patients were identified: 105 (45%) had DR-MM while the remaining 128 (55%) patients were classified as non-double refractory (NDR-MM). With median follow up of 42 months for surviving patients, at least partial response was seen in 188 (81%) patients (DR-MM, 83 [79%]; NDR-MM, 105 [82%]; p=0.77). Near complete remission or better was seen in 52 (22%) patients (DR-MM, 25 [24%]; NDR-MM, 27 [21%]; p=0.77). The median progression-free survival (PFS) was 17.6 months (14.4 months in the DR-MM patients and 18.2 months in the NDR-MM patients) and the 2-year PFS rate was 38% (DR-MM, 35%; NDR-MM, 40%; p=0.40). Median overall survival (OS) was 48.0 months (38.9 months in DR-MM and 56.6 months in NDR-MM) and the 2-year OS rate was 74% (DR-MM, 71%; NDR-MM, 76%; p=0.27).