The goal of this study is to determine the progression-free survival and objective response rate in subjects with either stage IIIB with pleural effusion NSCLC or stage IV NSCLC who are treated with up to six cycles of paclitaxel plus carboplatin and either tamibarotene or placebo. Subjects will be randomly assigned to receive tamibarotene, 6 mg/m2, divided as twice daily orally, or an equal number of matching placebo tablets, starting 1 week before chemotherapy and continuing through all 6 cycles and beyond. Subjects will be assessed for response on Day 50, Day 113, then every other month using the Response Evaluation Criteria in Solid Tumors (RECIST 1.1).