Molecular predictors of venous and arterial thrombotic events in patients with myelofibrosis.

While patients with myelofibrosis (MF) face an elevated risk of thrombosis, no validated scoring system currently exists to effectively assess this specific risk. This study aimed to explore distinct molecular risk factors for arterial (ATE) and venous (VTE) thrombosis in a cohort of 141 MF patients. Mutation analysis was performed by next-generation sequencing for a panel of 30 target myeloid genes as previously described: 137 driver and 164 non-driver mutations were detected. JAK2-V617F was identified in 77 (55%) patients, CALR in 45 (32%) patients, and seven (5%) patients carried an MPL variant. Patients #58 and #60 harbored JAK2-V617F and MPL; and patient #67 was positive for all three driver genes. The JAK2-V617F variant allele frequency (VAF) was assessed in 66/80 patients, revealing a median of 34.0% (range, 5.0-96.0). ASXL1 (n = 34 patients) were the most common non-driver mutations, followed by TET2 (n = 26), U2AF1 (n = 12), and DNMT3A (n = 11). During a median follow up of 4.8 years, 24 (17%) patients experienced VTE, 15 (11%) ATE, and two patients experienced both. Among the 24 patients with VTE, 12 (50%) experienced splanchnic vein thrombosis. The JAK2-V617F mutation was associated with VTE (OR 2.6, 95% CI 1.01-7.16), while the DNMT3A mutation was an independent predictor of ATE (OR 5.40, 95% CI 1.30-22.42). High JAK2-V617F VAF (> 50%) was not related with an increased thrombotic risk. Results of this study demonstrate the significance of DNMT3A mutations as an independent molecular risk factor for ATE, highlighting the potential to include these somatic non-driver mutations in future thrombosis risk scores.