Effect of an aromatic retinoic acid analog (Ro 10-9359) on growth of virus-induced papilloma (Shope) and related neoplasia of rabbits

An aromatic analog of retinoic acid (Ro 10-9359), a synthetic compound known to arrest development and growth of chemically-induced skin papillomas and carcinomas of mice, exerts a marked inhibitory effect on induction and development of virus-induced papilloma (Shope) of rabbit skin. The intramuscular administration of 12.5, 50 and 200 mg/kg given twice weekly during the induction phase of the neoplasia substantially inhibited the growth of the papilloma, this inhibition being dose-dependent. When the animals bearing well-established tumors were given a relatively large dose (200 mg/kg) of the compound, there was remarkable inhibition of the papillomatous growths and complete regression occurred in about 60%. The transplantable carcinomas Vx2 and Vx7, both of which originated from the Shope virus-induced papilloma, were less sensitive than their original papillomas to this treatment.