Real-World Eculizumab Dosing Patterns Among Patients with Paroxysmal Nocturnal Hemoglobinuria in a US Population

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INTRODUCTION Current pharmacologic management of patients who are diagnosed with paroxysmal nocturnal hemoglobinuria (PNH) includes C5 complement inhibitors, such as eculizumab. The standard dosage of eculizumab, administered via intravenous infusion, is 600 mg/week for the first 4 weeks (induction phase), 900 mg for the fifth dose 1 week later, and 900 mg biweekly thereafter (maintenance phase). There is limited information describing dosing patterns of eculizumab in clinical practice. The purpose of this study was to conduct a comprehensive assessment of the real-world dosing patterns of patients with PNH treated with eculizumab in a large US population. METHODS A retrospective longitudinal cohort study using provider-based claims data from the Symphony Health Integrated Dataverse® was conducted. Patients were ≥12 years of age and received ≥2 infusions of eculizumab between October 1, 2014, and September 30, 2019. The index date was defined as the first medical claim for eculizumab infusion with ≥3 months of prior continuous clinical activity, defined as ≥1 claim of any type per quarter (ie, the baseline period). Patients with ≥1 diagnosis of another indication for eculizumab, including atypical hemolytic uremic syndrome, generalized myasthenia gravis, and neuromyelitis optica spectrum disorder, during the baseline period or on the index date were excluded to identify patients with PNH. Patient baseline demographic and clinical characteristics, including PNH-related comorbidities and PNH-symptoms, were described. Mean starting dose and the proportion with high (>600 mg), label-recommended (600 mg), and low (<600 mg) starting dose during the induction phase were calculated. In addition, the mean and mode dose during the induction and maintenance phases, as well as the proportion of patients with high, label-recommended, and low mean dose during the induction and maintenance phases, were described. RESULTS A total of 707 patients with PNH who had ≥2 infusions of eculizumab during the study period were included in this analysis; mean observation period was 23.9 months. Mean age was 45.4 years, 55.7% were female, and 35.9% were from the South. The majority of patients (77.1%) were insured through a commercial insurance plan. Respectively, 32.5% and 6.8% of patients had a diagnosis for aplastic anemia and myelodysplastic syndrome during baseline. The most frequent comorbidities in this sample included hypertension (26.6%), coagulopathy (26.6%), and renal failure (20.5%). In addition, 85.1% of patients experienced anemia (other than aplastic anemia) at baseline. The mean (standard deviation) starting dose during the induction phase was 862 (412) mg; the proportion of patients with high, label-recommended, and low starting dose was 64.1%, 30.6%, and 5.4%, respectively. The mean (standard deviation) and mode dose was 859 (391) mg and 900 mg during the induction phase, and 1011 (333) mg and 900 mg during the maintenance phase. Respectively, 67.9%, 25.9%, and 6.2% of patients had a high, label-recommended, and low mean dose during the induction phase, and 45.9%, 41.6%, and 12.5% had a high, label-recommended, and low mean dose during the maintenance phase. CONCLUSIONS This study demonstrates that the majority of patients with PNH treated with eculizumab were started on a dose in the induction phase that was higher than the label-recommended dose of 600 mg, and the mean dose received during the maintenance phase was higher than the label-recommended dose of 900 mg in approximately half of all patients. Future analyses that investigate budget impact of eculizumab in patients with PNH should account for real-world dosing patterns in order to comprehensively assess costs and benefits. Disclosures Cheng: Apellis: Research Funding. Sarda:Apellis: Current Employment, Current equity holder in publicly-traded company. Mody-Patel:Apellis: Current Employment, Current equity holder in publicly-traded company. Krishnan:Apellis: Current Employment, Current equity holder in publicly-traded company. Yenikomshian:Apellis: Research Funding. Scoble:Apellis: Current Employment, Current equity holder in publicly-traded company. Kunzweiler:Apellis: Research Funding. Vu:Apellis: Research Funding. Cheung:Apellis: Research Funding. Duh:Merck: Research Funding; Pharmacyclics: Research Funding; Takeda Oncology: Research Funding; GlaxoSmithKline: Research Funding; AstraZeneca: Research Funding; Blueprint Medicine: Research Funding; Novartis: Research Funding; Shire: Research Funding; Apellis: Research Funding.