Challenges and Incidence of Apixaban Failure in Secondary Prevention of Deep Vein Thrombosis in Chronic Myelomonocytic Leukemia

This is the case of a 44-year-old female with a past medical history of pulmonary embolism 5 months prior to admission on apixaban therapy, morbid obesity, seizure disorder, and type 2 diabetes mellitus who presented with progressive dyspnea with onset occurring over the course of a few hours. The patient also endorsed chest pain, palpitations, and dizziness. She reported compliance with all medications including apixaban. However, she had been unable to follow up with her hematologist due to difficulty arranging transportation to clinic. She denied recent history of travel and was up to date on age-appropriate cancer screenings. CTA chest with contrast revealed bilateral pulmonary emboli (left greater than right) with evidence of right heart strain. Labs demonstrated a hemoglobin of 9.3, and troponin of 1.93. A review of labs from prior admissions were notable for a prior bone marrow biopsy and next-generation sequencing (NGS) with findings of chronic myelomonocytic leukemia, hypoproliferative subtype. The patient underwent mechanical thrombectomy and was discharged on warfarin due to treatment failure on apixaban. Chronic myelomonocytic leukemia (CMML) is a rare hematologic malignancy characterized by features of both myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). CMML accounts for less than 5% of all adult leukemia cases, with an annual incidence of approximately 4 cases per 1,000,000 individuals. The condition typically affects older adults, with a median age at diagnosis of 70 years. Due to its rarity, CMML is under-researched compared to other hematologic disorders, leading to challenges in diagnosis and management. The incidence of treatment failure for deep vein thrombosis (DVT) in patients with malignancy receiving apixaban is a critical area of study given the unique challenges posed by cancer-associated thrombosis. Apixaban is a direct oral anticoagulant (DOAC) that is commonly used for the prevention and treatment of DVT and pulmonary embolism (PE). In the context of malignancy, patients are at a higher risk for both thrombosis and bleeding, complicating anticoagulation therapy. Studies have indicated that while DOACs, including apixaban, are effective in the general population, the treatment failure rate in cancer patients can be higher due to the hypercoagulable state induced by malignancy and its treatments. In clinical trials, apixaban has shown a lower recurrence rate of venous thromboembolism (VTE) compared to low molecular weight heparin (LMWH) in cancer patients. However, real-world data suggests that the incidence of treatment failure, defined as recurrent DVT or PE, while on apixaban can still be notable in this population. This failure rate is influenced by factors such as the type and stage of cancer, patient comorbidities, and concurrent cancer therapies. Studies have reported recurrence rates ranging from 3% to 7% in cancer patients on apixaban, which underscores the need for careful patient selection and monitoring. In summary, while apixaban is a promising anticoagulant for treating DVT in patients with malignancy, treatment failure is a concern due to the complex interplay between cancer and coagulation. Continuous research and tailored therapeutic strategies are essential to optimize outcomes in this high-risk group