Study of Erlotinib in Patients With Non-Metastatic Prostate Cancer With a Rising Prostate Specific Antigen (PSA) on Hormone Therapy

Inclusion Criteria:

* Patients must have documented adenocarcinoma of the prostate, treated with androgen suppression, and now present with a rising PSA .
* Prior therapy with hydrocortisone is allowed (must have discontinued \> 4 weeks prior to study treatment). Prior use of ketoconazole for prostate cancer treatment is allowed (must have discontinued \> 4 weeks prior to study treatment).
* Prior therapy with chemotherapy is allowed if it was administered as neoadjuvant or adjuvant therapy related to primary treatment and was completed \> 6 months prior to starting study treatment.
* Testosterone level \< 50 ng/dl within 4 weeks prior to study treatment. Patients who have not undergone surgical castration must continue primary androgen suppression therapy (luteinizing hormone-releasing hormone \[LHRH\] agonist) while on protocol therapy.
* Patients may be receiving oral bisphosphonate therapy prior to study treatment and continue while receiving treatment, but must not begin treatment with bisphosphonate while receiving study treatment. Patients on oral bisphosphonates must have completed at least 4 weeks of bisphosphonate therapy prior to study treatment.
* Patients must have adequate major organ function. All values must be obtained within 4 weeks prior to study treatment.

  * Creatinine \< 1.7 mg/dL or a creatinine clearance \> 50 mL/min,
  * SGOT (AST), SGPT (ALT) \< 2X the institution's upper limit of normal,
  * Bilirubin \< 1.5 mg/dL,
  * ANC \> 1500/mm3,
  * Platelet (PLT) \> 100,000/mm3
* Patients must have Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1.
* Patients must be \> 18.
* Patients taking warfarin are eligible.
* Patients taking CYP3A4 inducers or inhibitors are eligible.
* Patients with a history of prior malignancy are eligible provided they were treated with curative intent and have been free of disease for the time period considered appropriate for the specific cancer.

Exclusion Criteria:

* No previous palliative radiation. Prior radiation to the primary site is allowed.
* HIV positive patients receiving combination anti-retroviral therapy are excluded from the study because of possible pharmacokinetic interactions with erlotinib.
* Patients with gastrointestinal tract disease resulting in an inability to take oral medication are ineligible.
* Patients must not have ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, symptomatic cardiac arrhythmia, or psychiatric illness that would limit compliance with study requirements.
* Patients must not have received prior targeted therapy, including no prior EGFR inhibitor.
* Patients must not have evidence of metastatic disease.