Hi @benice268, you might wish to contact a coordinator at Mayo Clinic Clinical Trials. Here's more information:
CANCER-RELATED CLINICAL STUDIES QUESTIONS
Phone: 855-776-0015 (toll-free)
https://www.mayo.edu/research/clinical-trials
The research coordinator can help find clinical trials that might be right for your father.

I agree with @hbp that a clinical trial is something to consider. Princess Margaret Cancer Centre in Toronto is a great cancer care facility.