Retinoids in the treatment of acute promyelocytic leukemia. Review of the literature.

Retinoids are derivates of vitamin A. They play an important role in embryogenesis and differentiation of normal cells. All-trans retinoic acid (ATRA, Tretinoin) and 13-cis retinoid acid (cRA, Isotretinoin) are the most important isomers. The first treatment with retinoids in a patient with an acute promyelocytic leukemia (APL) is reported in 1983. Since 1988 studies are done investigating the effect of retinoids in APL. These studies demonstrate, that retinoids can achieve a high remission rate in patients with APL but without curing patients. A combination with chemotherapy is always necessary. The main advantage of using retinoids in this disease is a rapid improvement of the hemostatic disorder and the absence of an aplastic phase. Side effects of retinoids are those of the hypervitaminosis A syndrome and have to be considered in every patient treated with this drug. The addition of alpha-Tocopherol seems to ameliorate the toxicity of retinoic acid (RA). The theoretical background of the treatment with retinoids in APL as well as the clinical studies done so far are explained in detail.