I've been on it Libtayo, for squamous cells that invaded lymph nodules in my neck. It is working in that its eliminated tumors but is still circulating but at low levels in my system. I'm monitored using a blood test called Signatera that compares the tumor that was removed to how much is still in my system. It shows levels that won't be picked up by scans way before they show. The infusions have been easy for me with minimal side effects.