OP25 – Possibility of lenvatinib as a new treatment for anaplastic thyroid cancer

      Hiroyuki, Iwasaki1; Haruhiko, Yamazaki1; Nobuyasu, Suganuma1; Daiji, Nemoto1; Hirotaka, Nakayama2; Katsuhiko, Masudo3 1 Department of Breast and Endocrine Surgery, Kanagawa Cancer Center, Yokohama, Kanagawa, Japan 2 Department of Surgical Treatment, Yokohama City University Hospital, Yokohama, Kanagawa, Japan 3 Department of Breast and Thyroid Surgery, Yokohama City University Medical Center, Yokohama, Kanagawa, Japan   Background: Anaplastic thyroid cancer (ATC) is associated with an extremely poor prognosis and is resistant to most chemotherapies. In 2015, only in Japan, lenvatinib was approved for both differentiated thyroid carcinoma (DTC) and ATC. In this study, we evaluated the overall survival of 15 patients treated with lenvatinib for ATC. We further investigated the potential of lenvatinib as a breakthrough in the treatment of ATC. Methods: Fifteen patients with a definite histological diagnosis of ATC were treated at our hospital. Surgical treatment was possible in seven patients, including debulking operation, and postoperatively, lenvatinib treatment was started while we waited for wound healing. The remaining eight patients could not undergo debulking operation, so lenvatinib was promptly approved as life-saving treatment. Results: Our patients had a lenvatinib response rate of 26.7% and a disease control rate of 33.3%. However, lenvatinib was associated with a 100% incidence of treatment-related AEs, and the most common AE observed was hypertension (86.7%). Additionally, dose interruptions and reductions were required for the development of tumor fistulae or other tumor-related AEs, and 7 patients (46.7%) discontinued treatment because of grade 3 or higher AEs. Regarding overall survival, 130.0 days was observed as the median. Conclusions: Our study demonstrated the effectiveness of lenvatinib against this often chemotherapy-resistant disease. However, lenvatinib is associated with a very high incidence of AEs, and this must be weighed against the benefits of treatment. Going forward, physicians should seek to prolong the prognosis, consider the treatment outcome and administration method, including neoadjuvant chemotherapy.


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