DT‐678 inhibits platelet activation with lower tendency for bleeding compared to existing P2Y(12) antagonists

The novel clopidogrel conjugate, DT‐678, is an effective inhibitor of platelets and thrombosis in preclinical studies. However, a comparison of the bleeding risk with DT‐678 and currently approved P2Y(12) antagonists has yet to be determined. The objective of this study was to evaluate the bleeding tendency of animals treated with clopidogrel, ticagrelor, and DT‐678. Ninety‐one New Zealand white rabbits were randomized to one of 13 treatment groups (n = 7). Platelet activation was assessed by flow cytometry and light transmission aggregometry before and after the administration of various doses of DT‐678, clopidogrel, and ticagrelor. Tongue template bleeding times were also measured before and after drug treatment. Treatment with P2Y(12) receptor antagonists caused a dose‐dependent reduction in markers of platelet activation (P‐selectin and integrin α(IIb)β(3)) and aggregation in response to adenosine diphosphate stimulation. At the same doses required for platelet inhibition, clopidogrel and ticagrelor significantly prolonged bleeding times, while DT‐678 did not. DT‐678 and the FDA‐approved P2Y(12) antagonists clopidogrel and ticagrelor are effective inhibitors of platelet activation and aggregation. However, unlike clopidogrel and ticagrelor, DT‐678 did not prolong bleeding times at equally effective antiplatelet doses. The results suggest a more favorable benefit/risk ratio for DT‐678 and potential utility as part of a dual antiplatelet therapy regimen.