Bendamustine-Based Regimens as Salvage Therapy in Refractory/Relapsed Multiple Myeloma Patients: A Retrospective Real-Life Analysis by the Polish Myeloma Group

Multiple myeloma (MM) is an incurable disease and patients become refractory to the treatment in the course of the disease. Bendamustine-based regimens containing steroids and other agents are among the therapeutic options offered to MM patients. Here, we investigated the safety and the efficacy of bendamustine used in patients with refractory/relapsed MM (RRMM). The patients were treated with bendamustine and steroids (n = 52) or bendamustine, steroids and immunomodulatory agents or proteasome inhibitors (n = 53). Response rates, progression-free survival (PFS), overall survival (OS) and frequency of adverse events were compared between both study groups. Most efficacy measurements were better in patients treated with three-drug regimens: overall response rate (55% versus 37%, p = 0.062), median PFS (9 months versus 4 months, p < 0.001), median OS survival (18 months versus 12 months, p = 0.679). The benefit from combining bendamustine and steroids with an additional agent was found in subgroups previously treated with both lenalidmide and bortezomib, with stem cell transplant and with more than two previous therapy lines. Toxicity was similar in both study groups and bendamustine-based therapies were generally well-tolerated. Our study suggests that bendamustine may be an effective treatment for patients with RRMM. Three-drug regimens containing bendamustine, steroids and novel agents produced better outcomes and had acceptable toxicity. The efficacy of bendamustine combined with steroids was limited.