Allosteric and ATP-Pocket BCR::ABL1 Inhibition In Vitro, and Characterising Ex Vivo Thrombo-Inflammatory Biomarkers and Thrombin Generation in Asciminib-Treated CML Patients.

Chronic myeloid leukaemia (CML) is driven by the t(9;22) forming the BCR::ABL1 fusion gene, leading to the development of hyper-myeloid proliferation. This led to development of tyrosine kinase inhibitors (TKIs) such as Imatinib, Nilotinib, and Ponatinib. However, resistance or intolerance to ATP-competitive TKIs remains a challenge for some patients. asciminib (ABL001), a novel TKI, targets the myristoyl pocket of ABL1 instead of the ATP-binding site, reducing resistance to mutations. As asciminib is linked to thrombocytopenia, its effects on platelet activation, endothelial function, and inflammation must be studied to assess its potential to promote thrombosis. The main objective of this study is to determine the potential of asciminib as a monotherapy in inducing pathological responses to platelets and endothelium over time within the vasculature. This study assessed the effects of TKIs including asciminib on platelets and thrombotic biomarkers. Washed platelets were used to measure granule secretion, thrombus formation, surface expression of glycoproteins, apoptosis, and viability. Plasma from chronically Asciminib-treated CML patients was analysed using sandwich ELISA for inflammatory and platelet-endothelial biomarkers, and thrombin generation assays were performed to study coagulation. This approach combined in vitro and ex vivo methods to explore the impact of asciminib on platelet function and thrombotic potential. The study shows that acute treatment with asciminib does not promote platelet activation or thrombus formation. Instead, it exhibits an inhibitory effect on thrombus formation in vitro and is associated with reduced thrombo-inflammatory biomarkers ex vivo in chronically treated CML patients. Asciminib was associated with increased thrombin generation over time, suggesting an effect on secondary haemostasis. Asciminib does not appear to induce a prothrombotic or proinflammatory state under the conditions studied, which may be advantageous for CML patients. However, the observed increase in thrombin generation over time suggests a potential effect on secondary haemostasis that warrants further investigation in controlled studies.