Trends in frontline treatment patterns for multiple myeloma among US veterans, 1999–2025.

Abstract

7576 Background: Frontline treatment for multiple myeloma (MM) has evolved substantially, transitioning from alkylating therapy to newer therapeutic classes, including immunomodulatory drugs, proteasome inhibitors, and monoclonal antibodies. Despite these advances, real-world treatment patterns remain heterogeneous, and MM therapies carry substantial toxicity and costs. Using nationwide Veterans Health Administration (VHA) data, an integrated health system with longitudinal follow-up, we characterized frontline treatment patterns for MM among US Veterans from 1999 to 2025. Methods: We identified Veterans diagnosed with MM in the VHA from 1999 to 2025. Diagnoses were confirmed using a published and validated natural language processing (NLP) algorithm, with the index date defined as the first MM-specific treatment, excluding dexamethasone alone. Patients receiving no MM-specific therapy or dexamethasone alone were excluded. Frontline treatments were defined as treatments initiated within 30 days of the index date. Treatments were captured using VA inpatient and outpatient pharmacy files, inpatient and outpatient procedure records for injectable agents, Fee Basis and Community Care data, and CMS Medicare Part D claims. Because the VHA does not require insurance approval, a 30-day window was used to define frontline treatment. Hematopoietic stem cell transplant was excluded to focus on trends in frontline treatments. MM-specific treatments were defined using a clinician-reviewed list of medications and relevant Current Procedural Terminology (CPT) codes. Results: We identified 4,738 Veterans with MM from 1999 to 2025. Median age was 72.1 years (IQR 65.1-78.1), and 96.7% were men. Non-Hispanic Black accounted for 20.1%, non-Hispanic White 55.6%, Hispanic 3.0%, and other races 1.5%. Median BMI was 27.6 (IQR 24.3-31.8), and 63.3% lived in urban areas. Melphalan predominated in 1999 (85.3%) but steadily declined. Cyclophosphamide use increased from 10.5% in 1999 to a peak of 29.2% in 2015, followed by a decline to 10.4% in 2024. Thalidomide use peaked in 2005 (61.8%) and declined to near zero by 2017. Lenalidomide use increased after 2006, reaching 78.1% in 2024. Bortezomib increased from 1.2% in 2004, peaking at 49.4% in 2015 and remaining common, whereas carfilzomib and ixazomib were infrequently used ( < 6%). Monoclonal antibody use expanded after 2019 with daratumumab, reaching 45.5% in 2024. Conclusions: Using national VHA data from 1999 to 2025, we describe real-world frontline MM treatment patterns among US Veterans, illustrating temporal shifts in therapeutic class use, including increasing adoption of monoclonal antibodies within an integrated, longitudinal health system.