THERAPY OF ENDOCRINE DISEASE: Response and toxicity of small-molecule tyrosine kinase inhibitors in patients with thyroid carcinoma: a systematic review and meta-analysis

Context: Many tyrosine kinase inhibitors (TKIs) have been studied in patients with thyroid carcinoma (TC). However, the effect and toxicity of various TKIs in differentiated TC (DTC) and medullary TC (MTC) patients have not been directly compared. The aim of the present systematic review and meta-analysis was to systematically summarize response and toxicity of TKIs in TC patients. Methods: All major databases were systematically searched for publications on TKIs in TC. Primary endpoint was objective response; secondary endpoints were clinical benefit, percentage TKI dose reduction/discontinuation, hand-foot syndrome, diarrhea, and nausea/vomiting. Meta-analysis was performed using an exact likelihood approach and a logistic regression. Pooled percentages and 95% CIs were reported. Results: In total, 22 publications were included. For DTC patients, gefitinib induced no objective responses. Pooled percentage was highest for pazopanib, 49 (95% CI 33-64)%, and was 17 (95% CI 12-24)% for sorafenib. For MTC, gefitinib and imatinib induced no objective responses, whereas sunitinib induced objective response in 43 (95% CI 14-77)%. For vandetanib and cabozantinib, these numbers were 40 (95% CI 34-46)% and 27 (95% CI 22-32)% respectively. Clinical benefit was found in 53 (95% CI 48-59)% of DTC patients on sorafenib, and in 84 (95% CI 79-88)% and 55 (95% CI 49-61)% of MTC patients on vandetanib and cabozantinib respectively. All TKIs were associated with considerable toxicity. Conclusion: The currently studied TKIs show a modest response, while side effects are not negligible. Therefore, we suggest to solely consider TKIs in TC patients with rapid progressive disease, for whom the benefits of treatment outweigh toxicity