Thrombosis Prophylaxis with Apixaban in Patients Treated with Asparaginase

Background: Acute Lymphoblastic Leukemia (ALL) outcomes have significantly improved over time with multi-agent chemotherapy, and the addition of asparaginase (ASP) has demonstrated the ability to prolong overall survival. ASP has multiple toxicities, and it remains a challenge to manage them safely, particularly coagulopathy and thrombosis (30-40% based on historical studies). The best prophylactic anticoagulation strategy in patients with acute leukemias, particularly ALL with asparaginase use, remains unclear due to severe coexisting thrombocytopenia and coagulopathy. Though the current guidelines recommend using Antithrombin (AT) replacement or low molecular weight heparin (LMWH) for thrombosis prophylaxis, the evidence is weak with concerns of thrombosis (Blood (2020) 136 (3): 328-338) with the use of fibrinogen concentrates(cryoprecipitate) and limited efficacy data with AT replacement and unfractionated heparin (UFH) for thrombosis prophylaxis. Due to potential "resistance" to LMWH and UFH from acquired AT deficiency with ASP use, our institution in 2017 has adopted the use of the direct Xa inhibitor, Apixaban for thrombosis prophyalxis. We report the safety and effectiveness of Apixaban for thrombosis prophylaxis with ASP.

Methods: In this retrospective study, we reviewed the data on 20 patients treated with ASP between 2017-2020. Thrombosis prophylaxis was instituted with Apixaban 2.5 mg PO Q 12 hourly for three weeks along with cryoprecipitate as needed for bleeding or fibrinogen levels <100 mg/dL (normal 160-450 mg/dL) to balance the risk of bleeding. Apixaban was held if platelet count <20,000/µL and for invasive procedures or clinically significant bleeding events. We evaluated demographic data, ALL risk category, type of ASP use, laboratory data (Table 1 & 2) for four weeks following ASP, amount of cryoprecipitate used, major bleeding, clinically relevant non-major bleeding (CRNMB), and thrombosis incidence. The medians of pertinent laboratory data were plotted on a graph. Descriptive statistics with medians, quartiles, frequencies, and percentages are reported.

Results: Among the 20 patients treated during this period, 18 (90%) had ALL, and 2(10%) had NK/T cell lymphoma. Of the patients with ALL, 67% had high risk and 33% with standard-risk ALL. The median age of this cohort was 29.5 years (range: 19-63 years), 80% were males, 70% white, 30% were Latino or Hispanic, median body mass index-BMI of 30.2 kg/m ²(19.4-40.7 kg/m ²) and 65% were non-smokers. The median baseline AT activity was 107% (79-221%), 95% used concurrent corticosteroids (65%- Prednisone, and 30% used Dexamethasone). The most common induction treatment was CALGB 10403 (55%). Of the total, 95% received pegylated ASP, and only one patient received Erwinia ASP due to prior history of anaphylaxis. The major toxicities attributed to ASP included 5% grade II and 15% grade III-IV aspartate aminotransferase (AST) or alanine aminotransferase (ALT) elevation, 20% had bilirubin elevation, 10% developed grade III-IV acute pancreatitis, and 5% developed severe hypertriglyceridemia needing aphaeresis. Two patients (10%) developed thrombosis [catheter associated deep venous thrombosis (DVT) and one patient with lower extremity proximal DVT] within 4 weeks of use of ASP, with one of the two patients (5%) developing (lower extremity proximal DVT) while on being off anticoagulation due to bleeding. Major bleeding or CRNMB developed in 5% (spontaneous splenic rupture from ALL leading to hemorrhagic shock). The median number of cryoprecipitate units used per patient during weeks 1,2,3, and 4 was 5(0-35), 5(0-40), 5(0-15), 7.5(0-15), respectively; No patients received fresh frozen plasma or AT concentrates.

Conclusions: With the use of Apixaban prophylaxis, the incidence of thrombosis was 10% within four weeks from ASP and 5% while on anticoagulation. The incidence of major bleeding or CRNMB was 5%. Hypofibrinogenemia, acquired AT deficiency due to ASP, was seen between days 7-21 after using ASP (figure 1 & 2) and recovered subsequently. This study demonstrates initial evidence of the safety and efficacy of Apixaban for thrombosis prophylaxis and cryoprecipitate infusions in patients treated with ASP.

Figure 1

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Figure 1

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