Kevetrin is not a "checkpoint inhibitor" in any way. That term specifically describes inhibiting the blocking of the binding of immune system cells to pathogens. Kevetrin's MOA is completely different, having nothing to do with the immune system. Kevetrin removes, if you will, the inhibition of programmed cell death. Hope that is helpful.
(PS there are cell life cycle "checkpoints", so you can think about Kevetrin as a cell life cycle checkpoint enabler.)