The primary purpose of this research study is to test the safety and possible harms of
cemiplimab/peg-interferon-alpha, when it is given to participants at different dose levels.
The researchers want to find out what effects (good and bad) cemiplimab/Peg-Interferon has on
participants with advanced cutaneous squamous cell carcinoma (aCSCC) so that they can find
the best dose to treat aCSCC and reduce side effects as much as possible.