Compounds which are specific or selective agonists of RAR&agr; receptors in preference over RAR&bgr; and RAR&ggr; receptors, and particularly compounds of the formula where R is a H, lower alkyl of 1 to 6 carbons, or a pharmaceutically acceptable salt, are useful for treating a malignant disease or condition in a mammal. In treatment of solid tumors the compound exhibit synergistic anti-proliferative effect with human recombinant interferon.