Endocrine side-effects of anti-cancer drugs: the impact of retinoids on the thyroid axis.

Bexarotene (Targretin), approved since 1999 as a second-line treatment for late stage cutaneous T-cell lymphomas, has been shown to induce significant hypothyroidism through TSH suppression. This review revisits, through a case report, mechanisms by which rexinoids repress the expression of TSHB gene as well as αTSH and TRH genes. It appears that rexinoids suppress TSH independently from tri-iodothyronine. Bexarotene also differently affects the gene expression of deiodinases 1 and 2 as well as the peripheral clearance of thyroxine. These data might open new ways of research on the potential interaction between thyroid axis and endogenous rexinoids.