I have just had probably my last infusion after 27 months on Libtayo. The first year and a half it was every 3 weeks then we switched to every 6 weeks. My metastatic Squamous Cell Carcinoma that had appeared in 1 kidney and associated lymph nodes started decreasing immediately and was gone after 12 months of treatment. Because of the complete response and the fact that there is not much available information on what to do after 2 years on this medication, my oncologist at Mayo has encouraged me to stop and rescan in a few months. The side effects have been very easy to live with. Sometimes I would have a bit of dizziness the day after infusion, and the tiredness/exhaustion is very real. I found that taking it very easy for 2 days right after the infusion would make the overall tired feeling better. Just listen to your body and rest. The hardest part has been a subtle change in the taste of food and my decreased appetite. A dry mouth problem complicates that for me also. I haven't been able to gain needed weight during this time, but have not lost any either. I would gladly continue treatment if needed because of a recurrence. Good luck to your mother and I hope she has an excellent response to treatment. I am glad to answer any other questions.