Early Adherence to Immunomodulators in Multiple Myeloma: Retrospective Observations from a Safety-Net Hospital

Background/Objectives: Multiple myeloma (MM) disproportionately affects older adults and racial/ethnic minorities, many of whom face socioeconomic barriers to care. Immunomodulators (IMiDs) are central to MM therapy, but their benefit relies on timely initiation and sustained adherence. In safety-net settings, barriers such as insurance approvals, Patient Medication Assistance Program (PMAP) enrollment, and Risk Evaluation and Mitigation Strategy (REMS) requirements may influence adherence. This study evaluated IMiD adherence during the first two years of therapy among socioeconomically vulnerable MM patients in a large safety-net hospital, with attention to PMAP enrollment and treatment delays. Methods: We conducted a retrospective cohort study of adults (≥18 years) with newly diagnosed MM between October 2010 and January 2022 who initiated lenalidomide or pomalidomide at a safety-net hospital. Adherence was measured using the proportion of days covered (PDC). Delays in initiation were defined as ≥1 month from diagnosis to first IMiD prescription fill. This threshold was selected a priori based on the REMS-mandated 28-day prescription supply limit for lenalidomide and pomalidomide, which establishes a natural monthly treatment cycle; a delay exceeding one full 28-day cycle before therapy initiation is operationally meaningful within the REMS framework. Results: Eighty patients met criteria (mean age 55.1 years; 56.3% Hispanic/Latino; 31.3% African American). Most were unemployed (63.8%), 42.5% uninsured, and 57.5% enrolled in PMAP. Only 12.5% achieved PDC ≥ 80%. Median PDC was higher among PMAP enrollees (0.40 vs. 0.31; p = 0.0293) and transplant-ineligible patients (0.46 vs. 0.27; p = 0.0218). Delays ≥ 1 month occurred in 65% of patients. Conclusions: Adherence to IMiDs was suboptimal in this younger safety-net cohort. Although PMAP improved adherence, program delays may reduce early treatment benefits, underscoring the need for streamlined access and targeted interventions to address both patient- and system-level barriers.