(3S, 4S)-PF-06459988 is the S enantiomer of PF-06459988 with less active. PF-06459988 is a potent irreversible inhibitor of T790M mutant epidermal growth factor receptor (EGFR). PF-06459988 has excellent selectivity against EGFR wild-type while possessing a minimally reactive electrophile that reduces the propensity of off-target labeling.IC50 & Target:EGFR