One-year efficacy and safety of ravulizumab in adults with paroxysmal nocturnal hemoglobinuria naive to complement inhibitor therapy: open-label extension of a randomized study

Background: Ravulizumab, the only long-acting complement C5 inhibitor for adults with paroxysmal nocturnal hemoglobinuria (PNH), demonstrated non-inferiority to eculizumab after 26 weeks of treatment in complement inhibitor-naive patients during a phase III randomized controlled trial. We present open-label extension results with up to 52 weeks of treatment. Methods: Patients assigned to ravulizumab every 8 weeks (q8w) or eculizumab every 2 weeks during the randomized primary evaluation period received ravulizumab q8w during the 26-week extension. Efficacy endpoints were lactate dehydrogenase (LDH) normalization, transfusion avoidance, breakthrough hemolysis (BTH), LDH levels, Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scale, and stabilized hemoglobin. Serum free C5 levels and safety were assessed. Outcomes as of the data cut-off (4 September 2018) were summarized using descriptive statistics. Results: Overall, 124 patients continued ravulizumab, and 119 switched from eculizumab to ravulizumab. During the extension, 43.5% and 40.3% of patients in the ravulizumab-ravulizumab and eculizumab-ravulizumab arms, respectively, achieved LDH normalization; 76.6% and 67.2% avoided transfusion. BTH decreased in the eculizumab-ravulizumab arm; no events were associated with free C5 > 0.5 mu g/mL while receiving ravulizumab. Overall, 73.4% and 65.5% of patients in the ravulizumab-ravulizumab and eculizumab-ravulizumab arms, respectively, achieved stabilized hemoglobin. Similar proportions of patients achieved > 3-point improvement in FACIT-Fatigue at week 52 (ravulizumab-ravulizumab, 64.5%; eculizumab-ravulizumab, 57.1%). All patients maintained free C5 <0.5 mu g/mL during the ravulizumab extension, including those who experienced C5 excursions > 0.5 mu g/mL while receiving eculizumab during the primary evaluation period. Adverse events were comparable between groups and decreased over time. Conclusion: In adult, complement inhibitor-naive patients with PNH, ravulizumab q8w for up to 52 weeks demonstrated durable efficacy and was well tolerated, with complete and sustained free C5 inhibition and a decreased incidence of BTH with no events associated with loss of free C5 control.