Study of CP-675,206 in Bacillus Calmette-Guerin (BCG)-Resistant Bladder Cancer

Inclusion Criteria: * Histologic diagnosis of transitional cell cancer of the bladder must have completed a transurethral resection of all visible bladder tumors, and have completed two previous 6-week courses with intravesical BCG. * Evidence of disease recurrence within 1 year of previous BCG treatment * Tumor tissue must be available from biopsy for study related immunohistochemical analysis * If sexually active must use reliable form of contraception while on study and for 4 weeks after last treatment * ECOG performance status of \<2 * Life expectancy of at least 6 months * Adequate hematologic, renal and liver function * Informed consent Exclusion Criteria: * No evidence of immunosuppression or treated with immunosuppressive therapy within 6 months * No prior radiation to the pelvis * No gross hematuria within 1 week prior to planned week 1 treatment * Cannot have previous intolerance to BCG * Cannot be seropositive for HIV, hepatitis B(HBV) or hepatitis C(HCV) per patient history * No evidence of metastatic disease * No prior treatment with anti-CTLA-4 monoclonal antibody * Can not be pregnant or lactating * No history of autoimmune disorder * No history of thyroid or adrenal insufficiency * No history of inflammatory bowel conditions, including diverticulitis, ulcerative colitis, Crohn's or celiac disease, intractable urinary tract infection