sirolimus + all-trans retinoic acid

Sirolimus + all-trans retinoic acid is an experimental combination therapy consisting of two small molecule drugs with immunomodulatory and antineoplastic properties. Sirolimus (also known as rapamycin) is a macrolide compound that acts as a potent inhibitor of the mammalian target of rapamycin (mTOR), thereby suppressing T-lymphocyte activation and proliferation, inhibiting cytokine-driven cell cycle progression, and reducing antibody production[3][5]. All-trans retinoic acid (ATRA; also known as tretinoin) is a derivative of vitamin A that functions primarily by binding to nuclear retinoic acid receptors (RARs), modulating gene expression involved in cell differentiation, proliferation, and immune regulation[7]. Preclinical studies have shown that the combination can influence regulatory T cell (Treg) induction, stability, homing marker expression, and suppressive function. Specifically, culturing naive human T cells with both agents can enhance the yield and functional activity of FOXP3+ regulatory T cells compared to either agent alone[2][4][10]. This suggests potential utility in autoimmune diseases or transplant rejection settings where immune tolerance is desired. The combination has been investigated in vitro for its effects on Treg biology but does not currently have established clinical indications.

Other names

rapamycin + ATRAsirolimus + tretinoin