Single Agent Erlotinib in Chemotherapy-naive Androgen Independent Prostate Cancer

Inclusion Criteria: * Documented prostate cancer regardless of Gleason score * Patients should be considered hormone refractory and androgen independent. They must fail LHRH analogues, and anti-androgen withdrawal trial. * Failure is confirmed by an increase in PSA value of 10% or more than the value immediately before, and confirmed by another assessment 2 weeks later. * Patients have to have measurable disease either biochemically using rising PSA or/and with metastatic disease to the bone or visceral organs. * Performance status of 2 or less using ECOG scale.· Adequate liver function tests with ALT/AST being \< 3x normal, total bilirubin of 1.5 or less, and adequate renal function measured by a creatinine of 2.0 mg/dl or less. Alkaline phosphatase values are never exclusion criteria if it is deemed related to bone metastases. * Patients need to have adequate bone marrow function. ANC of 1000 or above, Hgb of 9.0 g/dl or above, and platelets of 100,000 or above. If other causes are affecting plts counts such as autoimmune disorders, patients are allowed on study. * Patients with inadequate bone marrow function that is deemed related to bone marrow involvement with prostate cancer are allowed at the investigator's discretion. * Patients with other malignancies are allowed as long as there is no evidence of the other malignancy present at entry time, and it has been 3 years or more since the treatment for the other disorder was completed. * Patients with prior exposure to investigational therapies including vaccines are allowed on this study as long as their last exposure was 4 weeks prior to study entry.Patients with known bone metastases are allowed to receive intravenous bisphosphonates such as aredia or zometa. * Patients on oral bisphosphonates are also allowed. * Chemo Naive Exclusion Criteria: * Patients with prior exposure to Tarceva * Patients who have received any prior systemic chemotherapy for prostate cancer. Exposure to chemotherapy for other malignancies is allowed as long as last chemotherapy was completed 3 years prior to study entry. * Patients with prior malignancies are excluded except for those who have non-melanoma skin cancers or other cancers that are in remission with the last therapy given 3 years prior to enrollment. * Prior exposure to any form of steroids is allowed and is not considered exclusion criteria. * Performance status of 3 or above using ECOG scale. * Known HIV positive status Known CNS involvement with prostate cancer