Safety and efficacy of apixaban thrombosis prevention in pediatric patients with obesity and acute lymphoblastic leukemia.

Pediatric patients with acute lymphoblastic leukemia and lymphoma (ALL/LL) and obesity are at increased risk for venous thromboembolism (VTE). The PREVAPIX-ALL trial was an open-label, randomized, controlled trial assessing the safety and efficacy of apixaban for VTE prevention in pediatric patients with ALL/LL. An a priori subgroup analysis of patients with obesity in the PREVAPIX-ALL trial was planned because of increased VTE risk in this group. Patients with obesity, aged ≥2 to <18 years, central venous catheter, and chemotherapy containing asparaginase were randomized to apixaban (prophylactic dose) vs standard of care (SOC; no anticoagulation) during induction chemotherapy. The primary efficacy end point was a composite of nonfatal symptomatic and asymptomatic VTE and VTE-related death. The primary and secondary safety outcomes were major bleeding and a composite of major and clinically relevant nonmajor (CRNM) bleeding, respectively. A total of 82 PREVAPIX-ALL participants presented with obesity, of whom 42 were randomized to apixaban. For the primary efficacy end point, a significant decrease in VTE events was present in the apixaban arm (1/42 [2.4%]) as compared with the SOC arm (10/40 [25%]; relative risk [RR], 0.09; 95% confidence interval [CI], 0.01-0.97; P = .007). There was a statistically significant treatment obesity interaction, P = .03. No statistically significant difference was observed for the primary efficacy end point among the nonobese group (RR, 0.85; 95% CI, 0.53-1.37; P = .50). No statistically significant difference in major or CRNM bleeding was observed. Apixaban prophylaxis in patients with obesity and ALL/LL resulted in a statistically significant VTE risk reduction with no increase bleeding. This trial was registered at www.clinicaltrials.gov as #NCT02369653.