While the PD-1 pathway has garnered most of the attention in the checkpoint inhibition space so far, thanks to last year's approvals of Keytruda (pembrolizumab, Merck & Co. Inc.) and Opdivo (nivolumab, Bristol-Myers Squibb Co.), a 2010 Israeli start-up is advancing what appears to be a first-in-class compound against a new immune checkpoint protein.