Atopaxar and its effects on markers of platelet activation and inflammation: results from the LANCELOT CAD program.

Atopaxar is a reversible protease activated receptor (PAR)-1 thrombin receptor antagonist that interferes with platelet signaling. The effects of PAR-1 antagonists on biomarkers remain unknown. The primary objective was to assess the effects of atopaxar on biomarkers of inflammation and platelet activation. The LANCELOT-CAD trial randomized 720 subjects to atopaxar (50, 100, or 200 mg daily) or matching placebo for 24 weeks. Biomarkers were assessed at serial time points. A linear mixed model to account for repeated measures was used to evaluate the change in biomarker concentration from randomization across time to week 24. Least square means were determined from the linear mixed models. The concentration of sCD40L decreased on average over time by -553 (95 % CI -677, -429) ng/L in the combined atopaxar group versus -30.3 (-249 to 189) ng/L fall in the placebo arm (P < 0.001) and a dose-dependent trend was seen across treatment groups (P < 0.001 for trend). In contrast, Lp-PLA(2) mass rose on average over time by 12.6 (95 % CI 10.0, 15.3) ng/ml in the combined atopaxar group as compared with 2.6 (95 % CI -2.1, 7.3) ng/ml in the placebo arm (P < 0.001). Similarly, the concentration of IL-18 rose by 17.5 (95 % CI 12.4, 22.6) pg/ml in the atopaxar group versus a -1.2 (95 % CI -10.2, 7.8) pg/ml fall in the placebo group (P < 0.001). The effects of atopaxar on Lp-PLA(2) and IL-18 appeared to be dose-dependent (P < 0.001 for trend) and were observed in J-LANCELOT. Atopaxar did not have a significant effect on other inflammatory markers. In conclusion, atopaxar appeared to decrease sCD40L, but did not demonstrate an anti-inflammatory effect in patients with stable CAD. Although atopaxar increased the concentration of Lp-PLA(2) and IL-18, the clinical relevance of these findings remains unknown and warrants further investigation and validation.

Safety and tolerability of atopaxar in the treatment of patients with acute coronary syndromes: the lessons from antagonizing the cellular effects of Thrombin­Acute Coronary Syndromes Trial.

BACKGROUND: Atopaxar (E5555) is a reversible protease-activated receptor-1 thrombin receptor antagonist that interferes with platelet signaling. The primary objective of the Lessons From Antagonizing the Cellular Effects of Thrombin-Acute Coronary Syndromes (LANCELOT­ACS) trial was to evaluate the safety and tolerability of atopaxar in patients with ACS. METHODS AND RESULTS: Six hundred and three subjects were randomized within 72 hours of non-ST-elevation ACS to 1 of 3 doses of atopaxar (400-mg loading dose followed by 50, 100, or 200 mg daily) or matching placebo. The incidence of Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) major or minor bleeding did not differ significantly between the combined atopaxar and placebo groups (3.08% versus 2.17%, respectively; P=0.63), and there was no dose-related trend (P=0.80). The incidence of CURE major bleeding was numerically higher in the atopaxar group compared with the placebo group (1.8% versus 0%; P=0.12). The incidence of cardiovascular death, myocardial infarction, stroke, or recurrent ischemia was similar between the atopaxar and placebo arms (8.03% versus 7.75%; P=0.93). The incidence of CV death, MI, or stroke was 5.63% in the placebo group and 3.25% in the combined atopaxar group (P=0.20). Dose-dependent trends for efficacy were not seen. Atopaxar significantly reduced ischemia on continuous ECG monitoring (Holter) at 48 hours compared with placebo (relative risk, 0.67; P=0.02). Transient dose-dependent transaminase elevation and relative QTc prolongation were observed with the highest doses of atopaxar. CONCLUSION: In patients after ACS, atopaxar significantly reduced early ischemia on Holter monitoring without a significant increase in major or minor bleeding. Larger trials are required to fully establish the efficacy and safety of atopaxar. CLINICAL TRIAL REGISTRATION: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00548587.