Safety and efficacy of pegcetacoplan treatment for cold agglutinin disease and warm antibody autoimmune hemolytic anemia.

Cold agglutinin disease (CAD) and warm antibody autoimmune hemolytic anemia (wAIHA) are rare autoimmune hemolytic anemias characterized by red blood cell destruction, largely attributable to complement activation resulting in intravascular and extravascular hemolysis. Pegcetacoplan is a subcutaneously administered C3-targeted therapy, which may be suitable for treating CAD and wAIHA. In this open-label phase 2 study, analyses were conducted in two cohorts, one for patients with CAD and the other wAIHA. In each cohort, patients were randomly assigned to receive 270 or 360 mg/day pegcetacoplan for up to 48 weeks. Safety endpoints included the incidence and severity of treatment-emergent adverse events (TEAEs) and adverse events of special interest (AESI). Efficacy endpoints included change from baseline in hemoglobin (Hb), lactate dehydrogenase, absolute reticulocyte count, haptoglobin, indirect bilirubin, and Functional Assessment of Chronic Illness Therapy (FACIT)-fatigue scale. Thirteen (100%) and 10 out of 11 (91%) patients with CAD and wAIHA respectively experienced at least 1 TEAE. Ten patients had at least 1 serious adverse event; none were considered related to pegcetacoplan. The only treatment-related AESIs were injection site reactions. Pegcetacoplan increased Hb levels, reduced hemolysis, and increased FACIT-fatigue scale scores in the first weeks; at week 48 the median (interquartile range) change from baseline Hb for the CAD and wAIHA total groups was 2.4 (0.90 to 3.00) and 1.7 g/dL (‑1.40 to 2.90), respectively, and improvements in hemolysis and FACIT-fatigue scale scores were maintained. This study demonstrated that pegcetacoplan is generally well tolerated and suggests it can be effective in patients with CAD and wAIHA. Registered at www.clinicaltrials.gov (NCT03226678).