Cell-Penetrating Pepducin Therapy Targeting PAR1 in Subjects With Coronary Artery Disease

Abstract

Objective Pepducins are membrane-tethered, cell-penetrating lipopeptides that target the cytoplasmic surface of their cognate receptor. Here, we report the first human use of a protease-activated receptor-1–based pepducin, which is intended as an antiplatelet agent to prevent ischemic complications of percutaneous coronary interventions. Approach and Results PZ-128 was administered by 1 to 2 hours continuous intravenous infusion (0.01–2 mg/kg) to 31 subjects with coronary artery disease or multiple coronary artery disease risk factors. Safety, antiplatelet efficacy, and pharmacokinetics were assessed at baseline and 0.5, 1, 2, 6, 24 hours, and 7 to 10 days postdosing. The inhibitory effects of PZ-128 on platelet aggregation stimulated by the protease-activated receptor-1 agonist SFLLRN (8 μmol/L) at 30 minutes to 6 hours were dose dependent with 20% to 40% inhibition at 0.3 mg/kg, 40% to 60% at 0.5 mg/kg, and ≥80% to 100% at 1 to 2 mg/kg. The subgroup receiving aspirin in the 0.5 and 1-mg/kg dose cohorts had 65% to 100% inhibition of final aggregation to SFLLRN at 30 minutes to 2 hours and 95% to 100% inhibition by 6 hours. The inhibitory effects of 0.5 mg/kg PZ-128 were reversible with 50% recovery of aggregation to SFLLRN by 24 hours. There were no significant effects of PZ-128 on aggregation induced by AYPGKF, ADP, or collagen, indicating that the observed effects were specific to protease-activated receptor-1. The plasma half-life was 1.3 to 1.8 hours, and PZ-128 was nondetectable in urine. There were no effects on bleeding, coagulation, clinical chemistry, or ECG parameters. Conclusions PZ-128 is a promising antiplatelet agent that provides rapid, specific, dose dependent, and reversible inhibition of platelet protease-activated receptor-1 through a novel intracellular mechanism. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01806077.

Effects of genetic variation in protease activated receptor 4 after an acute coronary syndrome: Analysis from the TRACER trial

“…The most important finding from our work was that the rs773902 AA genotype conferred a significant reduction in GUSTO moderate or severe bleeding. Our findings may have implications for the future development of PAR inhibitors generally, and for PAR4 inhibitors specifically [28, 29]. …”

“…Our study should serve as basis for future studies that include sufficient numbers of African Americans or patients with other cardiovascular conditions, such as those with chronic stable disease. It will also be important to consider PAR4 functional variants in those on-going trials of PAR4 antagonists in platelet-mediated cardiovascular diseases [28, 29] or other conditions where PAR4 or race may play a pathophysiologic role.…”

Proteinase-activated receptors (PARs) as targets for antiplatelet therapy

“…The mixed success of PAR1 competitive antagonists in the clinic has fuelled development into alternative strategies to target PAR activity. Although the approaches that offer allosteric regulation of PAR activity seem like an attractive therapeutic option, their success will not be known until the outcome of ongoing clinical trials [49]. …”

“…Unlike vorapaxar, no adverse bleeding was reported when PZ-128 was tested in nonhuman primates [48]. Recent studies testing the clinical efficacy of PZ-128 in patients with vascular disease have now shown faster elimination rates with plasma levels of PZ-128 undetectable after 24 h [49]. Whether this improves the bleeding severity and safety profile remains to be determined.…”

Challenges and Opportunities in Protease-Activated Receptor Drug Development

“…This mechanism of action implies the controversial contention that individual GPCRs couple to G proteins via unique determinants of interaction. However, despite concerns regarding specificity (44)(45)(46), the anti-PAR1 pepducin PZ-128 (previously P1pal-7) (47) was evaluated recently in a limited Phase I study in patients with coronary artery disease ( Table 2) (48). PZ-128 targets the intracellular PAR1-G protein interface by mimicking ICL3 of PAR1 and has been shown to inhibit PAR1-mediated human platelet activation selectively ( Figure 2) (49).…”