A Phase 3 Study of Ravulizumab (ALXN1210) Versus Eculizumab in Adults with Paroxysmal Nocturnal Hemoglobinuria Naive to Complement Inhibitors: Results of a Subgroup Analysis with Patients Stratified By Baseline Hemolysis Level, Transfusion History, and Demographics
Authors: Weitz Ilene C. , Kulagin Aleksandr , Nakao Shinji , Piatek Caroline I. , Szer Jeffrey , Rottinghaus Scott T. , Volles Lori , Damokosh Andrew I. , Aguzzi Rasha , Larratt Loree , Risitano Antonio M. 
Published: October 2019

Background/Objective: Ravulizumab (ALXN1210) is an innovative C5 inhibitor with high C5 affinity and a half-life approximately 4 times longer than eculizumab. In the largest interventional clinical study of C5 inhibitor-naive patients with paroxysmal nocturnal hemoglobinuria (PNH) to date, ravulizumab administered every 8 weeks (q8w) was shown to be noninferior to eculizumab (every 2 weeks [q2w]) across 2 coprimary endpoints and 4 key secondary endpoints, due to its ability to provide immediate, complete, and sustained inhibition of complement C5 (Lee et al, EHA-2018). Because PNH is a rare disease, prospective evaluation of new agents for the treatment of this disease, with the exception of ravulizumab, has been limited to small populations. As a result, assessing the effect of treatment in patients with unique disease characteristics and gaining a full understanding of the benefit-to-risk profile of new therapies, has been challenging. The objective of this protocol-specified analysis was to evaluate the relative efficacy of ravulizumab and eculizumab in adult patients with PNH based upon baseline hemolysis level, transfusion history, and demographics.

Methods: In this phase 3, randomized, open-label, noninferiority, multicenter study (NCT02946463), patients ≥18 years of age with confirmed diagnosis of PNH, naive to complement inhibitor therapy, with lactate dehydrogenase (LDH) level ≥1.5 times upper limit of normal (xULN), and ≥1 PNH-related sign/symptom at screening received ravulizumab or eculizumab over a 183 day study period. Coprimary efficacy endpoints were transfusion avoidance and LDH normalization. Secondary endpoints were percent change in LDH, change in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue score, proportion of patients with breakthrough hemolysis, and proportion with stabilized hemoglobin levels. Subgroup analyses were performed on each of these endpoints, based on transfusion history (0, 1-14, or >14 units of packed red blood cells [pRBCs] in the year prior to the first dose of study drug), screening LDH levels (1.5-<3 or ≥3 xULN), sex, age, race, and geographical region. Descriptive statistics are provided with no formal hypothesis testing performed.

Results: In total, 246 patients from countries across the Asia-Pacific region (n=124), Europe (n=91), North America (n=9), and South America (n=22) were randomized to ravulizumab (n=125) or eculizumab (n=121). For transfusion avoidance, the point estimates for 15/17 subgroups favored ravulizumab. The treatment effect favored ravulizumab irrespective of prior pRBC transfusion history and baseline LDH levels, as well as nearly all other demographic subgroups assessed (Panel A). With respect to LDH normalization, the point estimates for 11/17 subgroups favored ravulizumab. The treatment effect numerically favored ravulizumab among patients who received 1-14 and >14 pRBCs in the 12 months before randomization, both baseline LDH subgroups, and most of the demographic subgroups (Panel B). No sensitive subgroups were identified for either of the coprimary endpoints. Similarly, point estimates favored ravulizumab in the majority of patient subgroups across each of the key secondary endpoints, including: 8/17 of the subgroups on the assessment of percent change in LDH; 12/17 subgroups on the assessment of change in FACIT-Fatigue score; 13/17 subgroups on the assessment of breakthrough hemolysis; and 13/17 subgroups on the assessment of hemoglobin stabilization.

Conclusions: Results of this prespecified analysis revealed point estimates favoring ravulizumab for the majority of the diverse subgroups of PNH patients analyzed. The consistency of these data across subgroups confirms the robustness of the results of this study. The benefit of ravulizumab in terms of transfusion avoidance and LDH normalization was retained across all subgroups. These results provide evidence supporting the use of ravulizumab for the treatment of complement inhibitor-naive patients with PNH regardless of transfusion history, baseline hemolysis level, sex, age, race, or geographic region.

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Disclosures

Weitz: Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria. Kulagin:Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria. Nakao:Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria; Novartis: Honoraria; Kyowa Hakko Kirin Co., Ltd.: Honoraria. Szer:Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Other: Travel Support , Research Funding. Rottinghaus:Alexion Pharmaceuticals, Inc.: Employment, Equity Ownership. Volles:Alexion Pharmaceuticals, Inc.: Employment, Equity Ownership. Damokosh:Alexion Pharmaceuticals, Inc.: Employment, Equity Ownership. Aguzzi:Alexion Pharmaceuticals, Inc.: Employment, Equity Ownership. Larratt:Alexion Pharmaceuticals, Inc.: Honoraria, Research Funding. Risitano:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Alnylam Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Ra Pharmaceuticals, Inc.: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amyndas Pharmaceuticals: Consultancy.