I cannot help you with this particular cancer, but I want to let you know that in the worst case scenario there are very promising clinical trials of immunotherapeutic agents. I wrote several times about monoclonal antibodies to cell receptors PD1/PDL1 and others. Check my posts in "Articles of interest" Besides there are trials for CAR T cells. Of course, they take mostly those pts that exhausted all other options. But its good to remember and read about them now. Invasive and metastatic disease is difficult to beat with old drugs, and new exciting drugs are coming. But maybe he will be cured by cystoctomy (removal of bladder). Good luck to your father.