Safety, Efficacy, and Patient-Reported Outcomes From a Phase 2 Randomized Trial of Pozelimab and Cemdisiran Combination in Patients With Paroxysmal Nocturnal Hemoglobinuria.

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is an ultra-rare, life-threatening disease associated with chronic intravascular hemolysis due to uncontrolled complement activation. PNH results in anemia with an increased risk of thrombosis, and often causes severe fatigue, and decreased physical function and health-related quality of life (QoL). We investigated the efficacy, safety, and patient-reported outcomes data of the combination of pozelimab (a fully human monoclonal antibody) and cemdisiran (an -acetylgalactosamine-conjugated small interfering ribonucleic acid) from a Phase 2 trial (NCT04811716) in patients with PNH who transitioned from pozelimab monotherapy.

Methods: In this randomized, open-label, Phase 2 study, patients were randomized (1:1) to one of two treatment arms; both arms received subcutaneous cemdisiran 200 mg every 4 weeks (Q4W) plus subcutaneous pozelimab 400 mg either Q4W (Arm 1) or every 2 weeks (Arm 2).

Results: Twenty-four patients were treated with combination dosing. During the 28-week open-label treatment period (OLTP), 20 patients (83.3%) maintained control of lactate dehydrogenase (≤ 1.5 × upper limit of normal) at all timepoints. The majority of patients (92%) did not require a blood transfusion. While most patients (66.7%) experienced treatment-emergent adverse events, the majority of these events were mild to moderate in severity. No meningococcal infections, thrombotic events, or deaths were reported. The combination therapy maintained improvements in patient-reported fatigue, physical functioning, and QoL throughout the OLTP.

Conclusion: Combination treatment maintained adequate hemolysis control and was generally well tolerated. Administration of pozelimab Q2W did not improve disease control as compared to pozelimab Q4W.

Trial Registration: ClinicalTrials.gov/NCT04811716.