(Business 2.0) – Lung cancer patients could get new hope if the FDA approves Tarceva as expected in late January. The drug, from South San Francisco's Genentech, will initially be used to treat non-small-cell lung cancer when chemotherapy has failed. But Tarceva could eventually be used for other types of cancer, and analysts think annual U.S. sales could top $500 million in three to four years. Genentech's production partner on Tarceva may end up being the biggest winner: Struggling OSI Pharmaceuticals stands to reap a healthy share of the profits.