MM-146: A Real-World Study of Bendamustine Therapy in a Very Heavily Pre-Treated Population of Multiple Myeloma Patients

Abstract

<h3>Context</h3> Bendamustine is an alkylating agent with activity against multiple myeloma (MM), and in UK clinical practice, its use is predominately limited to patients who have no other therapeutic options. <h3>Objective</h3> Assessment of efficacy and toxicity of bendamustine in the real-world setting. <h3>Design</h3> Retrospective case-review study including patients commenced on bendamustine Jan. 2016–Jan. 2021 (follow-up until May 2021). <h3>Setting</h3> A UK tertiary MM center. <h3>Patients</h3> Twenty-nine patients received bendamustine and corticosteroids, 14 in combination with thalidomide, with a median of 5 prior lines of therapy. Cytogenetic data were available in 19; 95% (18/19) had high-risk-disease at their most recent assessment prior to commencing bendamustine. <h3>Interventions</h3> Bendamustine was given at 60 mg/m² D1,2; dexamethasone/methylprednisolone weekly; thalidomide 50–200mg daily (28-day cycle). <h3>Main Outcomes Measures</h3> Overall response rate (ORR, ≥partial response, PR), clinical benefit rate (CBR, ≥minimal response, MR), progression-free survival (PFS), overall survival (OS), and toxicity. <h3>Results</h3> The median PFS of the cohort was 1.8 months (median follow-up 13 months), and the OS was 4.8 months. Of the 29 patients, 23 were assessable for response (4 completed <1 cycle, 2 had a secretory disease). The ORR was 26% (6/23, all PR), and the CBR was 39% (9/23). Achievement of ≥PR was associated with longer PFS and OS (median PFS 5.3 months <i>vs</i> 1.8 months, p=0.10; OS 14 months <i>vs</i> 4.1 months, p=0.15). Toxicity assessment was performed in the whole cohort. Twenty-eight percent (8/29) had received ≥5 cycles at time of data cut-off and 3 remain on treatment. The reason for stopping therapy was progression in 65% (17/26) and death in 23% (6/26). One patient stopped treatment due to significant cytopenias, 1 due to frailty, and 1 because bendamustine had been used as a bridge to alternative therapy. Thirty-four percent (10/29) only completed ≤1 cycle of therapy, 3 died, 6 progressed, and 1 had severe cytopenias. Fifty-five percent (16/29) required transfusion of platelets and/or red blood cells during their treatment. <h3>Conclusions</h3> In this very heavily pre-treated population, bendamustine was associated with an ORR of 26%, and the overall PFS and OS were short at 1.8 and 4.8 months, respectively. However, achieving ≥PR was associated with a longer PFS and OS (5.3 and 14 months, respectively), suggesting bendamustine may provide a therapeutic option for a subgroup of patients when no others are available.