Thyroid dysfunction in patients treated with tyrosine kinase inhibitors, sunitinib, sorafenib and axitinib, for metastatic renal cell carcinoma.

OBJECTIVE: Targeted drugs are generally associated with a lower toxicity than conventional systemic cytotoxic drugs and, thus, are administered for long periods. As a result, unusual adverse effects, including thyroid dysfunction, have become important clinical issues.

METHODS: We retrospectively collected the data and compared the incidence and the time of onset of thyroid dysfunction in 33 patients (M/F: 26/7, age: 34-77) with metastatic renal cell carcinoma treated with the small-molecule tyrosine kinase inhibitors (TKIs) sunitinib, sorafenib and axitinib in Yamagata University Hospital, Japan, from 2005 to 2010.

RESULTS: The incidence of thyroid dysfunction tended to be higher in patients treated with axitinib (6 of 6: 100%) than in those treated with sunitinib (9 of 15: 60%) or sorafenib (6 of 12: 50%) (P= 0.1113). The median thyroid dysfunction-free survival evaluated using the Kaplan-Meier product-limit method with the log-rank test was significantly shorter in patients treated with axitinib than in those treated with sunitinib/sorafenib (3 vs. 16 weeks, P=0.0198). A multivariate Cox regression model for thyroid dysfunction-free survival with several probable confounding factors as co-variables showed that patients treated with axitinib were more likely to have thyroid dysfunction than the others (hazard ratio: 4.53, 95% confidence interval: 1.40-14.63, P=0.0116).

CONCLUSIONS: Patients treated with the tyrosine kinase inhibitors developed thyroid dysfunction frequently. Furthermore, those treated with axitinib developed thyroid dysfunction significantly more and at a faster rate than the others. Therefore, when the tyrosine kinase inhibitors, especially axitinib, are used, close monitoring of thyroid function is recommended, at least for the initial 1-2 months, to avoid clinical symptoms derived from thyroid dysfunction.