Safety and tolerability of the protein C activator AB002 in end-stage renal disease patients on hemodialysis: a randomized phase 2 trial.

Background: The protein C system regulates blood coagulation, inflammation, and vascular integrity. AB002 is an injectable protein C activating enzyme under investigation to safely prevent and treat thrombosis. In preclinical models, AB002 is antithrombotic, cytoprotective, and anti-inflammatory. Since prophylactic use of heparin is contraindicated during hemodialysis in some end-stage renal disease (ESRD) patients, we propose using AB002 as a short-acting alternative to safely limit blood loss due to clotting in the dialysis circuit.

Methods: This phase 2, randomized, double-blind, placebo-controlled, single-dose study evaluates the safety and tolerability of AB002 administered into the hemodialysis line of ESRD patients during hemodialysis at one study center in the United States (ClinicalTrials.gov: NCT03963895). In this study, 36 patients were sequentially enrolled into two cohorts and randomized to AB002 or placebo in a 2:1 ratio. In cohort 1, patients received 1.5 µg/kg AB002 (n = 12) or placebo (n = 6); in cohort 2, patients received 3 µg/kg AB002 (n = 12) or placebo (n = 6). Patients underwent five heparin-free hemodialysis sessions over 10 days and were dosed with AB002 or placebo during session four.

Results: Here we show that AB002 is safe and well-tolerated in ESRD patients, with no treatment-related adverse events. Clinically relevant bleeding did not occur in any patient, and the time to hemostasis at the vascular access sites is not affected by AB002.

Conclusions: As far as we are aware, this proof-of-concept study is the first clinical trial assessing the therapeutic potential of protein C activation. The results herein support additional investigation of AB002 to safely prevent and treat thrombosis in at-risk populations.