Real world outcomes of lenalidomide or bortezomib maintenance in patients with multiple myeloma not undergoing stem cell transplantation

Maintenance is one form of long-term therapies in multiple myeloma (MM). Lenalidomide and bortezomib are two commonly used options. The role of maintenance in patients not undergoing transplant remains unclear. A total of 248 newly diagnosed MM patients who received over 180 days of any standard-of-care induction therapy and did not receive autologous stem cell transplantation were included. Patients either receive lenalidomide, bortezomib or no maintenance. Patterns of usage, survival benefit, discontinuation status were analyzed. 93, 99 and 56 patients received no, lenalidomide (Len) and bortezomib (Bor) maintenance respectively. Patients receiving Bor had a higher incidence of traditional high-risk cytogenetics (14.0% (No) vs 14.1% (Len) vs 41.1% (Bor), P < 0.001). Len maintenance conferred a superior progression-free survival (PFS) and overall survival (OS) compared to no maintenance (median PFS, 60.1 vs 26.9 months, P = 0.003; median OS, NR vs 56.7 months, P = 0.046), with a near independent impact on PFS (adjusted HR 0.580, P = 0.058). The PFS and OS benefit of Len maintenance was seen in subgroups of ISS stage I/II, traditional standard-risk cytogenetics, and pre-maintenance < CR. Bor maintenance did not confer PFS or OS benefit for the entire cohort, but improved OS in patients with pre-maintenance < CR. Discontinuation due to toxicity was recorded in 11.1% and 8.9% of patients receiving Len or Bor maintenance respectively. Our study supports lenalidomide maintenance as the standard-of-care in MM patients not undergoing transplant. Further studies are warranted for bortezomib maintenance in the non-transplant setting, and better maintenance strategy is needed for patients with adverse prognostic factors.