By Ransdell Pierson Jan 27 (Reuters) - Pfizer Inc on Monday said one of its experimental drugs had failed to meet its goals in two late-stage studies among patients who had received prior treatment for advanced non-small cell lung cancer, the most common form of the disease. Although Pfizer continues to test the drug, called dacomitinib, in another Phase III study, hopes for its success have now largely faded, according to ISI Group analyst Mark Schoenebaum. "We believe consensus expectations (for the drug) will be close to zero given today's readout" of unsuccessful trial results, Schoenebaum said in a research note. In one of the failed trials, called ARCHER 1009, patients given Pfizer's once-daily pill did not show improved survival without the cancer worsening, compared with Roche Holding AG's widely used Tarceva (erlotinib). Tarceva is the current standard of care in patients with mutated forms of a protein called Epidermal Growth Factor Receptor (EGFR). The protein plays a role in normal regulation of cell growth, but when mutated is believed to cause cells to proliferate and thereby help spur various types of cancer. Dacomitinib is designed to block several types of Epidermal Growth Factor receptors, while Tarceva and similar treatments for lung cancer target only one type of receptor. Cowen and Co had forecast annual sales of $500 million by 2020 for dacomitinib, if it were approved for lung cancer. That would make it a moderate-sized product for Pfizer, the largest U.S. drugmaker, which has annual revenue of $50 billion. Schoenebaum said there has been little investor interest in the drug and that Wall Street had expected it to generate annual sales of only $300 million by 2018. The second failed trial, named BR.26, involved patients that previously had failed to benefit from chemotherapy as well as from treatment with an EGFR inhibitor. Overall survival of patients taking the Pfizer drug was not prolonged in the study, compared with patients given a placebo. Pfizer said adverse events seen with dacomitinib were consistent with those seen in smaller earlier studies. In the meantime, Pfizer said dacomitinib is also being tested in a third late-stage trial, called ARCHER 1050, among patients with advanced non-small cell lung cancer who have not received prior treatment. The study will compare dacomitinib with Iressa (gefitinib), an EGFR inhibitor sold by AstraZeneca Plc. Results from that study are expected in 2015. Pfizer shares were little changed in morning trading on the New York Stock Exchange.