Monica Fay, PharmD, Senior Vice President of Global Medical Affairs at Apellis Pharmaceuticals, discusses recent data from the PRINCE study, a phase 3 study of pegcetacoplan in patients with paroxysmal nocturnal hemoglobinuria (PNH).

PNH is a rare, life-threatening blood disorder characterized by hemolysis. Persistently low hemoglobin levels can result in severe fatigue and difficulty breathing. Additionally, individuals with PNH are susceptible to thrombotic events and many have some degree of bone marrow dysfunction. In May 2021, the U.S. Food and Drug Administration (FDA) approved pegcetacoplan to treat PNH.

As Dr. Fay explains, data from the phase 3 PRINCE study (NCT04085601) were recently presented at The American Society of Hematology Meeting & Exposition (ASH 2021). The purpose of the PRINCE study was to evaluate the efficacy and safety of pegcetacoplan compared to standard of care in patients with PNH. The co-primary endpoints were hemoglobin stabilization through Week 26 and reduction in lactate dehydrogenase (LDH) compared to standard of care, which did not include complement inhibitors, at Week 26. 

In the study, hemoglobin stabilization was achieved by 85.7% of pegcetacoplan-treated patients and 0.0% of standard of care patients through Week 26. Pegcetacoplan-treated patients also demonstrated superior reductions in mean LDH levels from baseline to Week 26 compared to standard of care patients. Pegcetacoplan was also superior to standard of care in the secondary endpoints: mean CFB in hemoglobin levels (pegcetacoplan, 2.9 g/dL vs. standard of care, 0.3 g/dL); Week 26 mean hemoglobin: (12.8 g/dL vs 9.8 g/dL); and transfusion avoidance (91.4% vs 5.6%). 

Serious adverse events (AEs) were reported by 8.7% of pegcetacoplan-treated patients and 16.7% of standard of care patients through Week 26. The most common AEs reported during the study were injection site reaction (pegcetacoplan, 30.4% vs standard of care, 0.0%), hypokalemia (13.0% vs 11.1%), and fever (8.7% vs 0.0%). There were no AEs leading to discontinuation of pegcetacoplan.

Dr. Fay notes that all participants of the PRINCE study have gone on to participate in a long-term extension study. She also notes that next steps for Apellis’ pegcetacoplan program include identifying long-term benefits of the drug for PNH patients.

To learn more about PNH and other rare blood disorders, visit