Successful treatment switch from lenvatinib to sorafenib in a patient with radioactive iodine-refractory differentiated thyroid cancer intolerant to lenvatinib due to severe proteinuria.

Sorafenib and lenvatinib showed efficacy for patients with radioactive iodine (RAI)-refractory differentiated thyroid cancer (DTC) in pivotal phase 3 clinical trials. Although the efficacy of lenvatinib in patients who received previous treatment with multi-target kinase inhibitors (m-TKIs), including sorafenib, was reported, the efficacy of sorafenib in patients who previously received lenvatinib remains unknown. A 75-year-old woman diagnosed as RAI-refractory poorly differentiated carcinoma with multiple lung metastases and started treatment with lenvatinib. She continued to receive lenvatinib but with repeated dose interruptions and reductions due to continuous proteinuria. Because of severe and persistent proteinuria as well as newly developed renal impairment, lenvatinib was suspended after two years of treatment. After the 7-month suspension, her proteinuria and renal impairment were partially improved, but her lung metastases progressed. Because she was unable to tolerate previous treatment with lenvatinib, sorafenib was started. At 7 months of treatment with sorafenib, her lung metastases shrank and she could continue sorafenib without exacerbation of proteinuria or renal impairment. This case may suggest that sorafenib does not exacerbate the proteinuria or renal impairment induced by lenvatinib, and may be an effective treatment option for RAI-refractory DTC patients who are unable to tolerate lenvatinib.