From Triple- to Penta-Exposed Multiple Myeloma: A Real-World Study in a Medicare Population

Introduction: Treatment of multiple myeloma (MM) has been transformed by novel therapies, including CD38 monoclonal antibodies (mAbs), immunomodulatory drugs (IMiDs), and proteasome inhibitors (PIs), resulting in increasing numbers of patients who are triple-class exposed (TCE; exposed to ≥ 1 drug in each class). Many patients are penta-exposed (PE; ≥ 2 IMiDs, ≥ 2 PIs, and a CD38 mAb), some are triple-class refractory (TCR), and some are PE and TCR (PE-TCR). Data on real-world outcomes in elderly patients with MM across this spectrum of exposure are limited.

Methods: Data from the Medicare Chronic Conditions Warehouse Database from November 2006-December 2020 were used to examine cohorts of TCE, TCR, PE, and PE-TCR patients. Outcomes were assessed from the start of the index line of therapy (LOT), defined as the first LOT after becoming TCE or PE.

Results: A total of 2830 TCE, 1371 TCR, 1121 PE, and 774 PE-TCR patients were identified. Pomalidomide was the most frequently used medication for the index LOT in all cohorts (32.6% [PE-TCR] to 43.3% [TCR]). The most frequently used regimens for the index LOT were pomalidomide plus daratumumab for TCE (17.2%) and PE (7.0%), pomalidomide plus carfilzomib for TCR (10.3%), and pomalidomide plus elotuzumab for PE-TCR (7.4%). Median time to discontinuation (TTD) ranged from 4.2 (PE-TCR) to 6.9 (TCE) months, and overall survival (OS) ranged from 13.0 (TCR) to 15.9 (PE) months. Healthcare resource utilization (HRU) was lowest for TCE and highest for PE-TCR patients. Mean monthly healthcare costs (HCC) ranged from $23,091 (TCE) to $24,412 (PE-TCR). MM medications represented 66.2% (PE-TCR) to 72.8% (TCE) of costs.

Conclusions: In this study across a spectrum of Medicare TCE patients, there was heterogeneity in treatment regimens, suggesting no standard of care. TTD and OS were short, and HRU and HCC were high. These results underscore the potential for new therapies in this population.