Preliminary report of the effects of complement suppression with pexelizumab on neurocognitive decline after coronary artery bypass graft surgery

Background and Purpose - Pharmacological modulation of complement activation recently has been postulated as a therapeutic target in the treatment of neurological injury. We hypothesized that pexelizumab, a humanized scFv monoclonal antibody directed against the C5 complement component, would limit deficits in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass. Methods - The Phase II Pexelizumab study was a 914-patient, double-blind, placebo- controlled, 65-center study of patients undergoing coronary artery bypass graft surgery. Patients were randomized to pexelizumab bolus, bolus plus infusion, or placebo. Neurological and neurocognitive functions were assessed as secondary endpoints at baseline and on postoperative days ( POD) 4 and 30. Cognitive deficits were assessed with multivariable tests accounting for baseline cognition, age, diabetes, years of education, sex, elevated creatinine, history of myocardial infarction, neurological disorder or congestive heart failure, and cardiopulmonary bypass time. Results - Pexelizumab had no statistically significant effect on the primary composite endpoint or on overall cognition. When domain specific effects were examined, a decline of at least 10% in the visuo-spatial domain was observed on POD 4 in 56% of patients receiving placebo compared with 40% receiving pexelizumab by bolus and infusion ( P = 0.003). Similarly, on POD 30, a 10% decline was present in 21% of patients in the placebo group versus only 12% of the drug bolus plus infusion group ( P = 0.016). No differences were seen between treatment groups in any of the other domains. Conclusions - Pexelizumab administration for 24 hours perioperatively had no effect on global measures of cognition but may reduce dysfunction in the visuo-spatial domain.