Neuroendocrine Tumours

Hi there, I am new to this Forum and would like to start off by saying that my brother was diagnosed with neuroendocrine tumors in his lung and lymph nodes in July 2019. To cut a very long story short he has hormone injections on a monthly basis and has been on Chemo, tablet form, for 9 months, which was working but isn't now because he now has tumours in his chest and his liver and also been diagnosed with skin cancer, this is all within the last 6 months. The Chemo tablets have been stopped,  there is nothing can be done to cure my brother, therefore he's terminal but he has just been started on a drug, Everolimus, which apparently targets the tumours in the hope they will shrink and also as long as he can tolerate the drug, of course. I am trying to read up on this drug and to be honest am a bit confused. If he can tolerate the side effects can the drug shrink the tumours, how long could someone be on this drug and if it does its job can it double your survival rate. Any information would be very very grateful, with many thanks.