Selective retinoids and rexinoids in cancer therapy and chemoprevention.

Natural and synthetic retinoids are effective inhibitors of tumor cell growth in vitro and in vivo. However, the toxicity of natural derivatives of vitamin A limits their therapeutic use. Recently, synthetic compounds selective for the different retinoid receptor isotypes have been generated that circumvent pan-retinoid toxicity. The tumor-suppressive activity of selective retinoid and/or rexinoid ligands has been established preclinically, and emerging clinical trials are supportive of the chemotherapeutic and chemopreventive potential of these compounds in multiple oncology indications, with reduced toxicity. Moreover, the combination of retinoids and/or rexinoids with chemotherapeutic agents for the synergistic modulation of specific pathways could also be of benefit in cancer therapy.