Lapatinib, Cisplatin, Gemcitabine as First-Line Therapy in Treating Patients With Locally Advanced or Metastatic Urothelial Cancer

DISEASE CHARACTERISTICS: * Histologically proven transitional cell carcinoma of the urothelial tract * Metastatic or locally advanced disease * Measurable disease according to RECIST * Involvement of at least one target not in previously irradiated fields * Overexpressing HER1 and/or HER2 receptors (HER2 3+ by IHC OR HER2 FISH or CISH positive) * No clinical signs of CNS involvement PATIENT CHARACTERISTICS: * WHO performance status 0-1 * ANC ≥ 1,500/mm³ * Thrombocytes \> 100,000/mm³ * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * AST/ALT ≤ 3 times ULN * Creatinine clearance ≥ 60 mL/min * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective double-barrier contraception during and for 3 months after completion of study treatment * Cardiac ejection fraction normal * Normal 12 lead ECG * No serious cardiac illness or medical condition within the past 6 months including, but not limited to, any of the following: * Documented congestive heart failure * High-risk uncontrolled arrhythmias * Angina pectoris requiring antianginal medication * Clinically significant valvular heart disease * Evidence of transmural infarction on ECG * Poorly controlled hypertension (e.g., systolic blood pressure \[BP\] \> 180 mm Hg or diastolic BP \> 100 mm Hg) * No peripheral neuropathy \> grade 1 * Able to swallow and retain oral medication * No other malignancy within the past 3 years except basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix * No active or uncontrolled infections, serious illnesses, malabsorption syndrome or medical conditions, hepatitis, HIV, and/or cirrhosis * No psychological, familial, sociological, or geographical condition potentially hampering study protocol compliance or follow-up schedule * No current active hepatic or biliary disease (with the exception of Gilbert's syndrome, asymptomatic gallstones, liver metastases or stable chronic liver metastases or stable chronic liver disease) PRIOR CONCURRENT THERAPY: * Recovered from any effects of surgery * Intravesicle therapy for superficial disease allowed * Prior neoadjuvant or adjuvant chemotherapy allowed * Must have a minimum interval of six months between the completion of neoadjuvant or adjuvant chemotherapy and the diagnosis of metastatic disease * No prior chemotherapy for metastatic disease * No radiotherapy within the past 4 weeks * No drugs and herbal inducers or inhibitors of CYP3A4 (e.g., bergamottin or glabridin) within 10 days prior to study treatment and while receiving lapatinib ditosylate therapy * No other concurrent anticancer therapy or investigational agents * No other concurrent anticancer agents * No concurrent treatment with other investigational therapy for other diseases or conditions * No concurrent prophylactic antibiotics * No concurrent prophylactic filgrastim (G-CSF) * At least 14 days since prior and no concurrent herbal or dietary supplements * No concurrent consumption of grapefruit juice