A Study to Determine Best Tumor Response With Trastuzumab Emtansine in Human Epidermal Growth Factor Receptor 2 (HER2) Overexpressing Solid Tumors

This multicenter, non-randomized, Phase II study will assess the efficacy, safety, and pharmacokinetics of trastuzumab emtansine in participants with HER2 overexpressing locally advanced (unresectable and not treatable with curative intent) or metastatic urothelial bladder cancer (UBC), locally advanced (unresectable and not treatable with curative intent) or metastatic pancreatic cancer/cholangiocarcinoma with advanced disease where cure is no longer possible and where no other treatment options are available anymore. Participants will receive intravenous (IV) infusion of trastuzumab emtansine as Regimen A (2.4 milligrams per kilogram \[mg/kg\], weekly \[qw\]) or Regimen B (3.6 mg/kg, every 3 weeks \[q3w\]) until unacceptable toxicity, withdrawal of consent, disease progression (PD), or death, whichever occurs first. Based on tolerability and safety aspects, steering committee and Independent Data Monitoring Committee (iDMC) will decide on expansion of the study to include more participants with other carcinoma types.