Outcomes of maintenance therapy with lenalidomide or bortezomib in multiple myeloma in the setting of early autologous stem cell transplantation.

Post-transplant maintenance is widely used in multiple myeloma (MM); however, there is a lack of data on real-world outcomes. We have analyzed 577 patients with newly diagnosed MM undergoing early auto-transplantation between 2010 and 2015. A total of 341, 132 and 104 patients received no, lenalidomide (Len) or bortezomib (Bort) maintenance, respectively. Patients receiving Len or Bort maintenance had a higher incidence of high-risk cytogenetics by fluorescence in situ hybridization (31% (Len) vs 58% (Bort) vs 8% (No); P<0.001). Len maintenance led to a superior progression-free survival (PFS) compared with no maintenance (median, 37 vs 28 months, respectively; P=0.002; adjusted hazard ratio 0.48 (95% CI, 0.35-0.66)), including in subgroups with ISS stage III disease (median, 40 vs 24 months; P=0.008) and high-risk cytogenetics (median, 27 vs 16 months; P=0.032). Bort maintenance did not confer PFS benefit for the entire cohort, but improved PFS in the high-risk cytogenetic subgroup (median, 28 vs 16 months; P=0.035). Discontinuation due to toxicity was seen in 17 and 7% of patients receiving Len or Bort maintenance, respectively. Our results indicate that post-transplant maintenance with Len or Bort is well tolerated in clinical practice and improves PFS in high-risk subgroups of MM patients.