PO108 | DIRECT ORAL ANTICOAGULANTS IN PATIENTS WITH VENOUS THROMBOEMBOLISM RECEIVING LONG-TERM IMMUNOSUPPRESSIVE THERAPY AFTER LIVER AND KIDNEY TRANSPLANTATION: A SINGLE-CENTER EXPERIENCE

U. Mazzarelli¹, L. Agrelli¹, A. Cirillo¹, C. Crescenzo², M. Triggiani¹, A. Guida³ | ¹Dipartimento di Medicina Interna, Università degli studi di Salerno, Italy; ²UOC Nefrologia e Trapianti di rene; ³Centro per le malattie emorragiche congenite e malattie trombotiche, AOU San Giovanni di Dio e Ruggi d'Aragona Salerno, Italy

Background and aims. Managing oral anticoagulation in solid organ transplant (SOT) recipients is challenging due to complex thrombo-hemorrhagic risks and pharmacokinetic drug-drug interactions (DDIs). Most immunosuppressants (calcineurin and mTOR inhibitors) and direct oral anticoagulants (DOACs) share the CYP3A4 and P-gp pathways, risking sub-or-supratherapeutic drug levels. These case reports evaluate the safety and efficacy of DOACs in liver and kidney transplant patients.
Case reports. Case 1. A 62-year-old female, kidney transplant recipient due to IgA nephropathy, was managed with apixaban 2.5 mg BID for previous recurrent femoral deep vein thrombosis (DVT). At the 3-month follow-up, neither thrombotic recurrence nor hemorrhagic events were observed. Both tacrolimus levels and apixaban plasma concentrations remained consistently within the therapeutic range. Case 2. A 70-year-old male, kidney transplant recipient with paroxysmal atrial fibrillation treated with dronedarone, developed an idiopathic popliteal DVT. Due to potential multiple DDIs, a reduced dose of apixaban 2.5 mg BID was started after a short course of low-molecular-weight heparin (LMWH). During a 9-month follow-up, the patient presented with significant anemia without clear blood loss. Endoscopy revealed an ampulloma, necessitating temporary discontinuation of anticoagulant therapy, which was resumed 2-weeks later without further complications. Case 3. A 55-year-old male, renal transplant recipient with a history of recurrent superficial vein thrombosis (SVT) of the lower limbs, treated with rivaroxaban 10 mg. At the three-month follow-up, neither hemorrhagic nor thrombotic events were reported, serum levels of rivaroxaban, tacrolimus, and everolimus remained within the therapeutic range. Case 4. A 63-year-old male liver transplant recipient, originally transplanted for HCV-related cirrhosis, with idiopathic left common iliac vein thrombosis, treated with therapeutic dose of LMWH for two weeks, followed by apixaban 5 mg BID for six months, then apixaban 2.5 mg BID. Over a follow-up period exceeding one year, neither thrombotic recurrence nor hemorrhagic complications have been observed, with plasma levels of apixaban, tacrolimus, and everolimus consistently remaining within the therapeutic range. Case 5. A 56-year-old male kidney transplant recipient, for IgA nephropathy, is currently receiving apixaban 2.5 mg BID for previous right iliofemoral venous thrombosis. Throughout the six-month observation period, serum levels of tacrolimus, everolimus, and apixaban have consistently remained within the therapeutic range.
Conclusions. Our real-world data, although based on a small patient cohort, suggest that DOACs represent an effective and viable therapeutic strategy for managing DVT in transplant recipients. In our population, no thrombotic recurrences were observed, and the safety profile remained favorable with an acceptable risk of bleeding. Monthly monitoring of plasma levels for both immunosuppressants and DOACs proved essential in managing drug-drug interactions in these clinically challenging patients. Close multidisciplinary collaboration with nephrologists and hepatologists allowed for a tailored approach, confirming that an integrated model of care is fundamental to optimizing outcomes in such a fragile clinical setting.