Urinary Bladder Neoplasm

This clinical trial is looking at a combination of drugs called trastuzumab and pertuzumab. This combination of drugs is approved together as standard of care treatment for adult patients with breast cancer (often with other anti-cancer drugs). This means it has gone through clinical trials and been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK. Trastuzumab and pertuzumab work in patients with these types of cancers which have a molecular alteration called HER2 amplification or HER2 activating mutation. Investigators now wish to find out if it will be useful in treating patients with other cancer types which are also HER2 amplified or HER2 mutated. If the results are positive, the study team will work with the NHS and the Cancer Drugs Fund to see if these drugs can be routinely accessed for patients in the future. This trial is part of a trial programme called DETERMINE. The programme will also look at other anti-cancer drugs in the same way, through matching the drug to rare cancer types or ones with specific mutations.