Risk Factors for Lenvatinib-Induced High-Grade Hypothyroidism in Patients with Hepatocellular Carcinoma: A Retrospective Study

Introduction: Lenvatinib mesylate (LEN) is an orally administered tyrosine kinase inhibitor used for the treatment of various cancers, including hepatocellular carcinoma (HCC). HCC treatment with LEN is associated with a very high incidence of adverse events, especially hypothyroidism. This study investigated the incidence of hypothyroidism due to LEN and the relationships between hypothyroidism incidence and patient demographics by analyzing clinical laboratory data from HCC patients treated with LEN. Methods: This was a single-center, retrospective study of HCC patients who received LEN between April 19, 2018, and September 30, 2020. The observation period was from 1 week before the start of LEN administration to 1 month after the end of administration. Results: In total, 61 patients with HCC were enrolled. High-grade hypothyroidism (CTCAE Grade 2-3) was found in 36.1% (22/61 patients). In high-grade hypothyroidism, eosinophil (EOSINO) count was significantly low (p = 0.029). The cutoff value of EOSINO count was estimated to be approximately 150/mu L. The adjusted odds ratios of high-grade hypothyroidism for current smoking and EOSINO count <150/mu L were 0.237 (95% confidence interval: 0.063-0.893) and 4.219 (95% confidence interval: 1.119-15.92), respectively. Conclusion: The results showed that noncurrent smoking and EOSINO count <150/mu L are risk factors for LEN-induced high-grade hypothyroidism.