Sorry to learn about the sufferings of your wife.
The fact is your wife has very poor prognosis as she is in stage 4 f breast cancer
along with brain metastasis
I understand your keenness to get the best possible treatment for your wife but the fact is nothing can be done now.
It will be better if you give more of psychological support to her and keep her cheerful.
Your whole family should spend quality time with her.
There is no point running after different treatments as no treatment can offer her any cure at this stage.
Keep life comfortable and easy for her as well as for your whole family.