So OSI, Roche and Genentech gambled in trying to prove Tarceva extended survival. Earlier trials of both Tarceva and Iressa showed that neither prolonged life when used with chemotherapy as an initial treatment for lung cancer. Suspecting that perhaps the chemotherapy and Tarceva had canceled each other out, OSI and its partners then decided to test the drug alone in patients whose cancer had not responded to chemotherapy. Tarceva is a more direct competitor of Iressa, since both are pills and are aimed at lung cancer. ImClone's drug, requiring an infusion, is approved for colorectal cancer. But all the companies hope to extend use of their drugs to different types of cancer. Tarceva is being tested for pancreatic cancer and a type of brain cancer, and Genentech executives are hopeful that it can be combined with Avastin. Steven Harr, an analyst at Morgan Stanley, which has done investment banking for OSI, estimated that worldwide sales of Tarceva could reach $1.5 billion a year.