Innovative therapy for refractory thyroid carcinomas

Abstract

In general, thyroid carcinomas can be classified as well differentiated thyroid carcinomas and undifferentiated thyroid carcinomas. Fortunately, more than 95% of the thyroid carcinomas are well differentiated types showing favorable prognosis, and for these carcinomas, surgery with radioiodine ablation is the most effective therapy. However, only a few therapeutic options are available to treat the patients with undifferentiated thyroid carcinomas, especially with refractory thyroid carcinomas that are not amenable to surgery or radioiodine ablation. Recently, many institutions are under investigation to find a new treatment modality for such carcinomas. For the hope of finding an innovative drug therapy for refractory thyroid carcinomas, we investigated the anticancer effects of 20 drugs on 8 thyroid carcinoma cell lines. We analyzed the effects of 12 well acknowledged chemotherapy drugs each tested at 3 different concentrations, and 8 additional chemotherapy and hormonal therapy drugs at 9 concentrations. In vitro chemosensitivity was tested using the adenosine-triphosphate-based chemotherapy response assay (ATP-CRA). The tumor inhibition rate (TIR; or cell death rate) or half maximal inhibitory concentration (IC50) was analyzed to interpret the results. For 12 well acknowledged chemotherapy drugs, the active drugs showing better chemosensitivity were defined as those resulting in ≥30% TIR. Of the 12 chemotherapy drugs, etoposide and vincristine were the most active drugs showing the highest chemosensitivity and of the 8 additional drugs, trichostatin A showed favorable outcome as an anticancer drug. The study was to find an innovative therapy for the refractory thyroid carcinomas and the results showed that chemotherapy drugs such as etoposide and vincristine showed evidence as active anticancer drugs in thyroid carcinoma cell lines. Also, trichostatin A result came out to be the next promising drug. Further investigation of the above drugs and combination test for their interaction effects should be continued for clinical application in near future.