Table 1.

EGFR-activating and resistance mutations in adenocarcinoma of the lung

Mutation	Frequency in EGFR-mutant lung adenocarcinoma (%)	Clinical properties
		Response rate to EGFR TKIs		Median PFS		Median OS
		%	Reference	Months	Reference	Months	Reference
Exon 19 deletions	45	82.8	13	11.5	13	30.8	171
		84.8	170	9.0	14	34	174
		63	171	11	12	17.7	172
		64	172	14.6	171	33.1	173
		70	173	12	174
				9.3	172
				9.8	173
L858R (exon 21)	40	67.3	13	10.8	13	14.8	171
		60.9	170	9.6	14	8	174
		50a	171	8.4b	12	20.5c	172
		62	172	9.7	171
				5	174
				6.9	172
Exon 20 insertions	2–9	The variable response to EGFR TKIs is thought to be related to the effect of varying insertion length on the drug-binding pocket175. Median OS of 16 months176 in one series and 4 years in another177.
G719X	3	~50	178	8.1	179	16.4	179
L861X	2	60	179	6		15.2
Exon 19 insertions	1	Case series report responsiveness to erlotinib180
T790M	0.5–3 (in some case series)	Associated with lack of response to EGFR TKIs in patients with EGFR-activating mutations41,179

^aP = 0.39 compared to exon 19 deletions in this series.

^bP = 0.075 compared to exon 19 deletions in this series.

^cP = 0.65 compared to exon 19 deletions in this series.

PFS, progression-free survival; OS, overall survival.