Rechallenge with Lenvatinib after Refractoriness to Initial Lenvatinib Followed by Sorafenib in a Patient with Metastatic Papillary Thyroid Carcinoma

Two tyrosine kinase inhibitors, lenvatinib and sorafenib, are available systemic therapies for patients with metastatic differentiated thyroid carcinoma. However, the treatment options for carcinoma refractory to both lenvatinib and sorafenib are limited. Here, we present a case of metastatic papillary thyroid carcinoma that showed resensitization to rechallenge with lenvatinib. A 72-year-old woman who had been diagnosed with papillary thyroid carcinoma with multiple lymph node and lung metastases progressed with the emergence of subcutaneous metastasis after 3 years of response to initial lenvatinib. Five months after switching to sorafenib, the tumor was enlarged with increased contrast enhancement on computed tomography, suggesting progressive disease. Three months after the reintroduction of lenvatinib, marked tumor shrinkage and a decrease in its contrast enhancement were seen. Rechallenge with lenvatinib showed tumor resensitization. Therefore, rechallenge with lenvatinib may be a treatment option in patients who have experienced progressive disease after initial response to lenvatinib and subsequent sorafenib.