The race to develop new immunotherapy treatments against cancer has sparked an unprecedented explosion in the oncology drug pipeline, with checkpoint inhibitors being of particular interest.

Earlier today, Sanofi and Regeneron demonstrated some promising data for cemiplimab in advanced cutaneous squamous cell carcinoma or CSCC, the second deadliest skin cancer after melanoma. The PD-1 targeting antibody demonstrated a 46.3% ORR, which will form the basis for a regulatory submission. The duration of the response remains to be confirmed, with Sanofi saying that 32 of 38 responses among the 82 patients enrolled are continuing.

If approved by the regulator, cemiplimab will be the 6th PD-1/PD-L1 to hit the market. It will be interesting to see how  the drug will stand out of the growing checkpoint inhibitor crowd. In fact, only this year there were 469 new PD-1/PD-L1 cancer checkpoint studies launched according to a global analysis conducted by Cancer Research Institute.

There is no denying that cemiplimab is going to be a late entrant to the market. However, none of the currently available PD-1/PD-L1 drugs have been approved to treat CSCC. In addition, some say that the anti-PD-1 mAb approach is superior to PD-L1 in some cancers. If that is proven to be the case, Sanofi and Regeneron could enter a more fragmented market with potentially greater opportunity to make its mark versus its rivals, especially the anti-PD-1 blockbusters Keytruda and Opdivo.