Table 1. Time-Dependent Inhibition Kinetic Parameters for Lazertinib, Osimertinib, and LN2057^a.

	WT EGFR			EGFR(L858R/T790M)			WT HER2
Compound	kinact (min–1)	KI (μM)	kinact/KI (M–1 s–1)	kinact (min–1)	KI (μM–1)	kinact/KI (M–1 s–1)	kinact (min–1)	KI (μM–1)	kinact/KI (M–1 s–1)
Lazertinib	0.648 ± 0.036	0.271 ± 0.015	35,800 ± 400	0.235 ± 0.0042	0.0340 ± 0.0011	115,000 ± 2,000	0.166 ± 0.0130	0.437 ± 0.059	6,310 ± 440
Osimertinib	0.690 ± 0.042	0.434 ± 0.032	26,400 ± 400	0.648 ± 0.036	0.256 ± 0.016	42,400 ± 600	n.d.b	n.d.b	14,000 ± 600
LN2057	0.335 ± 0.011	0.0989 ± 0.0039	56,500 ± 600	0.561 ± 0.041	0.224 ± 0.019	41,800 ± 700	0.924 ± 0.30	0.142 ± 0.013	42,000 ± 2,000

^aAll values were measured from a single experiment in duplicate. The ATP concentration was 1000 μM, and the Sox-based substrate sensor was 15 μM. Errors are reported as ± the standard error from the fit. n.d. – not determined.

^bA sufficient two-step fit was not possible due to the inability to reach the maximal inactivation rate at high osimertinib concentration (k_inact).