I assume that by "immunotherapy" you mean something like Keytruda. We also call BCG a form of immunotherapy that is used for non-invasive high-grade bladder cancer. If your grandmother is indeed stage 4 it is more likely that Ketruda is being used. This is a relatively new addition to bladder cancer treatment and has shown some real promise.
Several patients have posted here on the Forum about their experiences with this novel new treatment. At the very top of this page, on the upper right, there is a "SEARCH" function. You can use this to access a lot of posts from patients who mention Ketruda (not all are relevant to your questions, of course.)
Questions as to medications to have on hand or side effects should be directed to her doctors.
Sara Anne
Diagnosis 2-08 Small papillary TCC; CIS
BCG; BCG maintenance
Vice-President, American Bladder Cancer Society
Forum Moderator