Abstract 2009: ALX-0081 a Novel Anti-Thrombotic: Results of a Single-Dose Phase 1 Study in Healthy Volunteers and Further Development in Patients with Stable Angina Undergoing PCI

Background : ALX-0081 is a bivalent Nanobody ® based on the variable domain of naturally occurring heavy-chain only antibodies. It binds with high affinity to the A1 domain of von Willebrand Factor (vWF) and thereby blocks the interactions between platelets and vascular collagen. It selectively prevents thrombus formation under high shear stress conditions. Aim : Test ALX-0081 single IV infusions (60 minutes) dosed from 0.5mg to 12mg total in 40 male healthy volunteers in double-blind, randomized, placebo controlled study and assess pharmacokinetic (PK), pharmacodynamic (PD), safety and immunogenicity. Results : ALX-0081 displayed non-linear pharmacokinetic properties, following a 2 compartment model. Ristocetin induced platelet aggregation (RIPA) was analyzed as marker for PD effect with full inhibition (defined as measured levels dropping <10%) observed at ALX-0081 concentrations of ~ 400ng/ml. All subjects dosed ≥ 2mg achieved full RIPA inhibition at 1h post-dosing for maximum of 12h. ALX-0081 treatment was well tolerated and safe, no signs of bleeding were reported and no immunogenic response was detected. Target related mild and transient reductions of vWF and FVIII plasma levels were observed and all events were fully reversible. Phase Ib study design : double-blind, randomized, placebo controlled, multiple ascending dose study. ALX-0081 added to standard anti-thrombotic regimen (ASA, clopidogrel, UFH) in patients with stable angina undergoing elective PCI. Single-dose escalation will be followed by multiple dosing (up to 4 doses in 24h). Dose escalation will be guided by safety and efficacy marker. Endpoints: safety, pharmacological profile, biomarker (RIPA, RICO and ACT) and early clinical outcome (MACE, IMR, molecular marker). Conclusion : ALX-0081 can be administered safely over a wide range of dose-regimen. First results of the phase Ib study in stable angina patients will be presented.