P-285: Real-world clinical outcomes and treatment patterns among patients with triple-class exposed multiple myeloma: an analysis using the Connect® Multiple Myeloma Disease Registry

Introduction: Despite clinical advances in multiple myeloma (MM), most patients are refractory to treatment or relapse and eventually become refractory. Patients who have been exposed to the 3 main drug classes used to treat MM (immunomodulatory imide drug [IMiD] agents, proteasome inhibitors [PI] and anti-CD38 monoclonal antibodies [mAbs]) – i.e. triple-class exposed (TCE) – have generally poor clinical outcomes. As novel agents become available, it is important to understand their potential benefit to patients with TCE MM. This study described the treatment patterns and clinical outcomes in patients with TCE MM in real-world clinical practice in the United States.

Methods: We analyzed prospectively collected data from the Connect® MM Disease Registry (NCT01081028). The current study was conducted in multiple myeloma patients enrolled in the Connect MM® registry who became TCE from Nov 16, 2015 to Dec 31, 2020 and who had received an index treatment post-TCE status. The earliest available end date of the third treatment class was considered as the date patients became TCE. If patients received a subsequent line of treatment post-TCE date, that first treatment was defined as the index treatment and treatment initiation date was defined as the index date. Data analyzed included demographics, disease characteristics, prior treatment and class exposure/refractoriness, index treatments and classes, response rates (overall, complete, very good partial, and partial), progression-free survival (PFS), overall survival (OS), and time to progression (TTP).

Results: The Connect MM Disease Registry includes 317 patients with TCE MM, of whom 215 had received an index treatment post-TCE. Median follow-up from the index date was 11.1 months. Median age of index-treated patients was 68 years, 61% were male, 86% were White, 81% were from a community practice setting. Patients received 3 median lines of treatment (range, 1–9) before index treatment; 83% were IMiD agent refractory, 81% were anti-CD38 mAb refractory, 68% were double-class refractory (IMiD agent and PI), 56% were triple-class refractory, and 9% were penta-refractory. Index treatments were varied (101 monotherapy or combination regimens in total) and carfilzomib/dexamethasone (DEX) (7.4%) and daratumumab/pomalidomide/DEX (7.0%) were the most commonly used treatments. Overall response and complete response rates among patients with TCE MM were 31.6% and 5.1%, respectively; median PFS with the index treatment was 4.4 months (95% CI, 3.0–5.6); median OS was 12.5 months (95% CI, 10.2–15.3), and TTP was 6.3 months (95% CI, 4.6–8.6).

Conclusions: In the real-world prospective Connect MM Disease Registry, patients with TCE MM had poor response and survival outcomes, with TCE occurring at a median of 3 prior lines of therapy. This study highlights the need for more efficacious and accessible novel treatments for patients with TCE MM, irrespective of number of lines of prior therapy.