Cemiplimab (LIBTAYO®; cemiplimab-rwlc), a human programmed death receptor-1 
(PD-1) monoclonal antibody that binds to PD-1 and blocks its interaction with 
programmed death ligands 1 (PD-L1) and 2 (PD-L2), is being developed by 
Regeneron Pharmaceuticals and Sanofi Genzyme. The drug is being investigated as 
a treatment for various cancers and in September 2018 received approval in the 
USA for the treatment of patients with metastatic cutaneous squamous cell 
carcinoma or locally advanced cutaneous squamous cell carcinoma who are not 
candidates for curative surgery or curative radiation. This article summarizes 
the milestones in the development of cemiplimab leading to this first global 
approval for the treatment of advanced cutaneous squamous cell carcinoma.