Targretin has indicated chemotherapeutic activity against nonsmall-cell lung cancer and chemoprevention in rat mammary gland. Therefore, targretin was evaluated for the prevention of 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanol (NNK) and vinyl carbamate-induced lung tumors in female strain A mice. Three experiments were performed: (i) a dose-response study with vinyl carbamate-induced tumors; (ii) a limited treatment study also with vinyl carbamate and (iii) prevention of NNK-induced tumors. In the dose-response study, 0, 10, 30, 100 and 300 mg/kg targretin were administered after vinyl carbamate. Dose levels of 30 mg/kg and greater significantly decreased tumor multiplicity by >19%. However, the efficacy of 30 and 300 mg/kg was not significantly different demonstrating a shallow dose-response relationship. In the limited treatment study, 200 mg/kg targretin was administered to the mice from 4-13, 4-19, 4-25 and 23-25 weeks after vinyl carbamate. Administering targretin from weeks 4-19 and 4-25 decreased the multiplicity of tumors from 35.3 +/- 1.43 to 29.1 +/- 1.51 and 25.0 +/- 0.93, respectively, and along with administering it from weeks 23-25 decreased tumor size. In the third study, when targretin (100 and 300 mg/kg) was administered for 3 weeks after NNK followed by a 20 weeks holding period, tumor multiplicity was reduced from 10.6 +/- 1.13 to 6.38 +/- 0.75 and 4.60 +/- 0.70, respectively. Hence, targretin demonstrated both preventive and therapeutic activity with respect to mouse lung tumors supporting its further development as a preventive and therapeutic agent for lung cancer.
2005 Wiley-Liss, Inc.