Real-world comparison of adherence to branded 20 mg dexamethasone tablets and generic 4 mg dexamethasone tablets among patients with multiple myeloma.

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e19518 Background: Branded 20 mg dexamethasone tablets (BDex) is the first and only FDA-approved dexamethasone specifically indicated for the treatment of adult patients with multiple myeloma (MM) in combination with other anti-myeloma products. Generic oral dexamethasone is only available at lower dosages (e.g., 4 mg) despite the standard dexamethasone dosage for MM being 20 or 40 mg. The availability of 20 mg tablets would, therefore, reduce pill burden and assumably improve adherence in MM patients. The objective of this analysis was to quantify and compare adherence of BDex and generic 4 mg dexamethasone (GDex) among MM patients using real-world evidence. Methods: Using an open claims database, which included professional, hospital, and pharmacy claims for over 295 million individuals across the United States from 2015 to 2023, BDex and GDex users aged ≥18 years with MM were identified. Baseline summary statistics were generated and chi-squared and t-tests were performed comparing continuous and categorical variables respectively between the treatment cohorts. Treatment adherence was determined using a medication possession ratio for flexible time period (MPRF) given variable numbers of cycles across patients. MPRF was reported as both a continuous and binary measure (≥80%). Differences in MPRF were determined utilizing t-tests. Results: Between September 1, 2020 and June 30, 2023, 43 BDex and 3,775 GDex users meeting all study criteria, including ≥2 prescription claims, were identified. Overall, 30.8% were aged 18-64 years, 54.6% were male, 71.2% were insured through Medicare, and 20.3% were insured commercially. Bortezomib monotherapy, immunomodulatory agent monotherapy, and daratumumab and bortezomib were the most common treatment regimens (17.5%, 11.1%, 7.2%, respectively). Mean MPRF was significantly higher in BDex users compared to GDex overall (97.1% vs 89.5%, p <0.001), among those 18-64 (98.7% vs 89.1%, p <0.001), those with commercial insurance (99.9% vs 90.4%, p<0.001), and those with Medicare (96.1% vs 89.6%, p=0.048). A significantly greater proportion of BDex users were considered adherent compared to GDex patients (95.3% vs 78.4%, p=0.007). This trend was seen across age and payer sub-cohorts, with significant differences seen in those with Medicare (96.0% vs 78.7%, p= 0.035). Conclusions: Adherence to BDex was greater than to GDex in this MM study population overall, and for age group and payer sub-cohorts. Given these findings, physicians may want to consider overall pill burden and regimen complexity when prescribing MM treatment for their patients.