Lapatinib Ditosylate in Treating Patients With a Rising PSA Indicating Recurrent Prostate Cancer

This phase II trial studies how well lapatinib ditosylate works in treating patients with a rising prostate-specific antigen (PSA), a protein made by the prostate gland, indicating that prostate cancer has come back after previous treatment. Lapatinib ditosylate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth and may delay or prevent the progression of prostate cancer.