I hesitate to tell you this, but it's my story about Keytruda and you asked.
Keytruda + Chemo worked well and the 2 tumors went away. (NED).
BUT ... I didn't stop the Keytruda by itself when I was "CR" (Complete Response) and it went too far. It attacked my autoimmune system & I got COP - Cryptogenic Organizing Pneumonia.
I didn't have side effects with keytruda either.
I was warned by my oncologist before I started. I remember clearly and I had written it down even. She said it attacks immune system but it can go too far and that's exactly what happened. Honestly this is not something you can find in writing but it did happen to me and I know someone else in one of my healing circles who had something similar and blamed it on Keytruda.
Getting rid of COP has taken me 2 years And I am still tapering off of Prednisone which has a lot of awful side effects.
There's more to this story but I will stop here for now.
I only want to help you with your decision.