Three non-small cell lung cancer patients who developed pulmonary thromboses during osimertinib treatment and could safely resume concomitant anticoagulation treatment: a report of three cases.

Background: Previous phase III study has demonstrated that osimertinib, a third-generation epidermal growth factor receptor (EGFR)-tyrosine-kinase inhibitor (TKI), exhibits superior antitumor effects compared to first-generation EGFR-TKIs and successfully prolonged overall survival (OS) in patients with EGFR-mutated non-small cell lung cancer (NSCLC). Although first- and second-generation EGFR-TKIs are risk factors for venous thromboembolism (VTE), whether osimertinib increases the VTE risk remains unclear. In addition, no treatment strategy exists for patients with VTE during osimertinib. Here we present the clinical course of three patients with suspected osimertinib-induced VTE who were successfully treated with direct oral anticoagulation without recurrence VTE during osimertinib therapy. Case Description: Three male patients, aged 66-74 years, with NSCLC harboring EGFR mutations had been treated with osimertinib as the first- and second-line treatments, and developed VTE. All patients responded to osimertinib, and none showed disease progression at VTE onset. All patients were treated with direct oral anticoagulation and could resume osimertinib treatment. The progression-free survival (PFS) from VTE onset in each of the three cases was 11.4+, 7.7, and 6.1 months, respectively. The OS from VTE onset was 11.4+, 26.0, and 25.9+ months, respectively. Conclusions: We report the cases of three NSCLC patients who developed VTE during osimertinib. Osimertinib may cause VTE and should be used cautiously. In such cases, osimertinib treatment may be continued with direct oral anticoagulation therapy.