P12: TREATMENTS IN PATIENTS WITH RELAPSED/REFRACTORY MULTIPLE MYELOMA: RETROSPECTIVE CHART REVIEW OF REAL-WORLD OUTCOMES FOR STANDARD OF CARE
Authors: M-C Vekemans, M Delforge, S Anguille, J Depaus, N Meuleman, A Van de Velde, I Vande Broek, D Strens, S Van Hoorenbeeck, EJ Moorkens, J Diels, F Ghilotti, S Dalhuisen, S Vandervennet
Journal: HemaSphere (2022)

Introduction: The prognosis of patients with multiple myeloma has improved considerably with the introduction of immunomodulatory agents (IMiDs), proteasome inhibitors (PIs), and anti-CD38 monoclonal antibodies (mAbs). However, most patients relapse and require further therapy, with no clear standard of care (SOC). Data on how patients with relapsed/refractory multiple myeloma (RRMM) are treated in clinical practice and outcomes to these treatments in the real-world setting are lacking. This study aimed to evaluate the outcomes of patients with triple-class (IMiD, PI, and anti-CD38 mAb) and triple-line exposed RRMM using real-world data from patients in Belgium. Methods: This multicenter (7 non-academic and academic Belgian centers), observational study was conducted based on a retrospective chart review of adult patients with RRMM who had received ≥3 lines (IMiD, PI, anti-CD38-directed) of therapies (tri-exposed) and started subsequent treatment from March 2017 through May 2021. In patients meeting eligibility criteria, all treatment lines utilized were considered for analysis (as separate observations for patients who met the eligibility criteria more than once during the follow-up), with date of treatment initiation as specific baseline for each treatment line. Prognostic value with overall survival (OS), progression-free survival (PFS), and time-to-next therapy (TTNT) was evaluated using Cox proportional hazards models. Results: A total of 112 patients with 237 eligible treatment-lines were included; median follow-up was 16.6 months. In 45% of initiated treatment lines, patients were refractory to 4 or 5 therapies, 62% had ≥5 prior lines, 22% had extramedullary disease; in 48% of observations, time-to-progression (TTP) in prior line was <4 months. After patients were tri-exposed, >50 unique regimens were initiated, with the most common being carfilzomib + dexamethasone (14%), pomalidomide + dexamethasone + chemotherapy (8%), and ixazomib + lenalidomide + dexamethasone (6%). Among included observations, 4% were exposed to anti-BCMA agents. The most frequently initiated therapies were: PI only (19%), PI + IMiD combinations (17%), and regimens that included anti-CD38 antibodies (15%). Median OS was 9.79 months (95% CI: 7.79, 12.22), median PFS was 3.42 months (95% CI: 2.79, 4.27), and median TTNT was 3.61 months (95% CI: 3.09, 4.57). The following factors were prognostic for worse outcomes for OS (Figure) and PFS: higher refractory status (p<0.001), being male (p=0.001), older age (p<0.001), shorter duration of prior lines (p<0.001), shorter TTP in prior line (p=0.025), and higher lactate dehydrogenase levels (p<0.002). Conclusions: Real-world outcomes (OS, PFS, and TTNT) were poor in tri-exposed patients with RRMM. The wide variety of treatment regimens used in clinical practice confirms the absence of a clear SOC for these patients. These real-world data from patients in Belgium are consistent with those from other countries, underscoring the high unmet medical need for new and effective treatments for patients with RRMM.