Dabrafenib and Trametinib prolong coagulation through the inhibition of tissue factor in BRAF(v600e) mutated melanoma cells in vitro

BACKGROUND: Neoplastic cells promote a hypercoagulable state by the expression of cell surface proteins, such as tissue factor. In BRAF(v600) mutated melanoma patients upon BRAF inhibitors, a hypercoagulable state correlates with prognosis, while a down-regulation of the hemostatic parameters is observed in patients responders as compared to non responders. The present study was intended to better clarify the strict relationship between coagulation mediators and target therapy in melanoma. METHODS: The expression of tissue factor was investigated after the treatment with the BRAF inhibitor Dabrafenib and the MEK inhibitor Trametinib in the BRAF(v600e) mutated melanoma cell lines A-375 and SK-MEL-28, together with its ability to activate the coagulation cascade. RESULTS: Dabrafenib and Trametinib caused the down-regulation of TF in both cell lines A-375 and SK-MEL-28. For the cell line A-375 the effect was evident both at RNA and procoagulant activity; for the cell line SK-MEL-28 only at RNA level without any variation of the protein. Interestingly, when in contact with plasma deficient of factor VII, both cell lines were not able to activate the coagulation cascade. CONCLUSIONS: The present study provides the first in vitro observation that tissue factor expressed in melanoma cells may contribute to the modulation of the coagulation state of patients in the treatment with BRAF inhibitors.