PB0309 - Safety and Efficacy of Apixaban Therapy in an Obese Adolescent with Pulmonary Embolism

Background: There is growing evidence about the safety and efficacy of apixaban in obese adults with venous thromboembolism (VTE). Adult AMPLIFY trial showed no increase in relative risk for recurrent VTE or VTE-related deaths and reported decreased bleeding for apixaban in obese adults. Apixaban use in children is reported rarely as off-label and is currently being investigated in clinical trials. There is no published data regarding apixaban use in children/adolescents with obesity.

Aims: To report safety/efficacy of apixaban in an obese adolescent with pulmonary embolism (PE).

Methods: Case report, retrospective EMR review with IRB exemption.

Results: A 16-years-old obese female (weight=123.3 kg, BMI ≥ 99th%) with uncontrolled Type II Diabetes Mellitus, presented with an episode of syncope after prolonged inactivity associated with worsening fatigue, cough, and shortness of breath. Patient was tachycardiac, tachypneic, hypoxic, and tested COVID-19 IgG positive. CT angiogram (CTA) chest revealed large saddle PE with right ventricular (RV) strain (Fig.1) and bilateral ground-glass opacities. She underwent emergent pulmonary artery embolectomy and received IV unfractionated heparin for 4 days, transitioned to PO apixaban 10 mg bid for 7 days, then 5 mg bid for total of 6 months. Apixaban peak/trough levels were within adult therapeutic ranges (Table 1). Two months later, patient was readmitted for pericardial effusion requiring pericardiocentesis, with no recurrent VTE or bleeding. Chest CTA at therapy conclusion showed completely resolved PE.

In our patient, apixaban was administered at the fixed dose based on body weight-tiered regimen derived from pediatric population pharmacokinetic modeling reported in the pediatric SAXOPHONE study. Apixaban levels were within adult therapeutic ranges with complete PE resolution and without bleeding complications.

Conclusion(s): Our case report indicates that weight-based apixaban dosing may be appropriate for VTE therapy in obese adolescents. Ongoing studies (PREVAPIX-ALL, SAXOPHONE, CANINES), we hope, will verify our observation regarding apixaban use in obese children/adolescents.