Reinduction of cell differentiation and 131I uptake in a poorly differentiated thyroid tumor in response to the reverse transcriptase (RT) inhibitor nevirapine.

Our recent findings have shown that the reverse transcriptase (RT) inhibitors, nevirapine and efavirenz, used for 10 years in human immunodeficiency virus (HIV) disease, act as cytostatic and differentiating agents by modulating gene expression in several human tumor cell models. In dedifferentiated thyroid cancer, they reestablish thyroid-stimulating hormone (TSH) signaling, Na/I symporter (NIS), thyroglobulin peroxidase (TPO) expression, and even radioiodine uptake (RIU). In this paper, we describe the case of a 76-year-old woman who was affected by thyroid papillary carcinoma and who underwent a total thyroidectomy and a debulking of the right laterocervical region for lymph-node metastases, vessel infiltration, and neoplastic thrombosis of the internal jugular vein, followed by 3 radioiodine treatments. At restaging, a computed tomography scan revealed that distant metastases were mostly not taking up the radioiodine at the 131I whole-body scan (WBS). An analysis of tumor cells obtained by fine-needle aspiration biopsy of a right laterocervical lymph-node revealed cell anisokaryosis, nuclear pleomorphism, and scanty colloid, as well as the undetectable expression of thyroglobulin and NIS proteins. After starting a nevirapine treatment (NT), higher thyroglobulin levels were observed and some metastases exhibited a significant increase in radioiodine uptake, which led us to again treat the patient with 131I. Five (5) months later, the 131I-WBS revealed the disappearance of RIU in some metastases and its significant reduction in other lesions, with a parallel drop in serum thyroglobulin. No new metastatic lesion was revealed by rh-TSH-stimulated 131IWBS and 18F-flourodeoxyglucose positron emission tomography scan. Cells obtained from the right laterocervical lymph-node 2 months after NT exhibited a reduced nuclear pleomorphism, an increase in colloid production, and a significant upregulation of thyroglobulin and NIS protein expression. This first in vivo molecular and morphologic evidence of cell differentiation in human cancer and low toxicity of nevirapine strongly encourage its use in dedifferentiated thyroid cancer treatment.