PO005 | EXTENDED ANTICOAGULATION WITH DOACS IN PATIENTS AFFECTED BY HEMATOLOGIC MALIGNANCIES AND VENOUS THROMBOEMBOLISM: DOES LOW DOSE FIT ALL?

M. Biglietto, S. Sorella, L.V. Cappelli, B. Mandelli, D. Kasmi, E. Baldacci, A. Chistolini | Sapienza University of Roma, Italy

Background and Aims. Data on the extended treatment of venous thromboembolism (VTE) in the oncohematologic patients is lacking. The aim of our monocentric retrospective analysis was to evaluate the efficacy and safety in secondary prophylaxis of two different Direct Oral Anticoagulants (DOACs) treatment strategies (full-dose/low-dose) in onco-hematologic patients, based on the persistence of complete venous occlusion.
Methods. We included adult oncohematologic patients with objectively confirmed VTE and at least 12 months of follow-up from the start of DOAC treatment. During the acute-phase of VTE treatment (first 3-6 months), the patients were treated with therapeutic dose of anticoagulants. In the extended therapy, the patients were treated with full-dose DOAC in case of persistent complete thrombosis and with low-dose DOAC in case of partial or complete vein recanalization and active cancer. Follow-up visits were scheduled every three months and included monitoring for bleeding (B-AEs) and thrombotic adverse events (T-AEs). Imaging with doppler ultrasound or computed tomography was performed every six months as per institutional policy, or earlier if recurrence was suspected. B-AEs were classified according to the ISTH criteria.
Results. Patients’ characteristics and AEs are summarized in Table 1. Fourteen bleeding events (87.5%) occurred during full-dose treatment (1 major [severe metrorrhagia] and 13 CRNM) and 2 (12.5%) during low-dose treatment (1 major [cerebral hemorrhage], 1 CRNM). The 13 CRNM events during full-dose included 10 gastrointestinal bleedings, 1 epistaxis, 1 mild metrorrhagia and 1 hematuria associated with bladder catheter placement. The CRNM event during low-dose was a conjunctival bleeding. During extended phase, the incidence rates of B-AEs were 9.9 per 100 patient-years for full-dose therapy and 0.8 per 100 patient-years for low-dose therapy. Nine patients (6.1%) experienced recurrent thrombosis during extended therapy with DOACs, including 6 (66.7%) on full-dose and 3 (33.3%) on low-dose. During extended phase, the incidence rates of T-AEs were 4.3 versus 1.3 per 100 patient-years, respectively. During follow-up, five patients experienced a platelet count reduction between 50×10⁹/L and 100×10⁹/L, while none had counts below 50×10⁹/L.
Conclusions. Despite the indication bias inherent in this retrospective design, our findings suggest that in onco-hematologic patients, full-dose therapy may be appropriate for those with persistent complete venous occlusion due to a higher baseline risk of recurrence, which appears to remain significant over time: the higher incidence rate of T-AEs during full dose DOAC in the extended treatment could be accounted to a higher thrombotic risk associated with no vein recanalization. De-escalation to reduced-dose DOACs after vein recanalization appeared to reduce the incidence of bleeding events, particularly CRNM B-AEs.