@reaton1indracom
My story is very similar to yours. Immunotherapy for metastatic melanoma which was working great until the PMR started. High dose prednisone (20mg per day) which the oncologist wanted to have me wean down to 10mg per day before starting my treatments back up. Basically we worked at getting down to the 10mg, but I couldn't tolerate that low dose. (I have never gone back on the immunotherapy- my oncologist says that my body is telling me that it has had enough). I am now working with a rheumatologist working on a taper again. It's very frustrating.
I will try to think of any hints I could give you. Unfortunetly I had a brain met that bled so my writing skills aren't great. I am thrilled to still be able to read.