Additional Biomarkers beyond RAS That Impact the Efficacy of Cetuximab plus Chemotherapy in mCRC: A Retrospective Biomarker Analysis

Table 2

Efficacy outcomes according to RAS status and predictive model in training cohort.

	RAS assessable; (n=106)		RAS wild-type; (n=93)		RAS wild-type/; Model-defined responsive group; (n=66)		RAS wild-type/; Model-defined refractory group; (n=27)
	Cetuximab plus chemotherapy; (n=50)	Chemotherapy alone; (n=56)	Cetuximab plus chemotherapy; (n=45)	Chemotherapy alone; (n=48)	Cetuximab plus chemotherapy; (n=29)	Chemotherapy alone; (n=37)	Cetuximab plus chemotherapy; (n=16)	Chemotherapy alone; (n=11)
Overall response
CR	1 (2.0%)	0 (0%)	1 (2.2%)	0 (0%)	1 (3.4%)	0 (0%)	0 (0%)	0 (0%)
PR	28 (56.0%)	17 (30.4%)	27 (60.0%)	14 (29.2%)	23 (79.3%)	11 (29.7%)	4 (25.0%)	3 (27.3%)
SD	14 (28.0%)	21 (37.5%)	12 (26.7%)	19 (39.6%)	3 (10.3%)	14 (37.8%)	9 (56.3%)	5 (45.5%)
PD	7 (14.0%)	15 (26.8%)	5 (11.1%)	13 (27.1%)	2 (6.9%)	10 (27.0%)	3 (18.8%)	3 (27.3%)
Not assessable	0 (0%)	3 (5.4%)	0 (0%)	2 (4.2%)	0 (0%)	2 (5.4%)	0 (0%)	0 (0%)
ORR, %	58.0	30.4	62.2	29.2	82.8	29.7	25.0	27.3
OR	3.17		4.00		11.35		0.889
95% CI	1.42-7.05		1.68-9.51		3.44-37.44		0.155-5.084
p (Chi-square or Fisher’s)	0.004		0.001		<0.001		1.000
p for interaction test					0.006
Radical resection rate of LM, %	28.0	8.9	28.8	8.3	37.9	8.1	12.5	9.1
OR	3.97		4.47		6.93		1.43
95% CI	1.31-12.0		1.33-14.98		1.71-28.05		0.11-18.04
p (Chi-square or Fisher’s)	0.011		0.010		0.003		1.000
PFS, months
Median	9.5	5.6	9.8	5.3	11.8	4.8	7.8	8.2
95%CI	8.7-11.3	3.8-6.2	9.1-10.8	3.9-6.1	8.1-13.9	3.9-6.1	5.2-8.8	3.8-8.3
HR	0.60		0.52		0.25		1.25
95%CI	0.39-0.91		0.33-0.81		0.13-0.48		0.52-2.99
p (log-rank)	0.010		0.002		<0.001		0.588
p for interaction test					0.001
OS, months
Median	30.0	22.1	35.1	21.7	39.6	20.0	25.6	33.8
95%CI	15.3-42.6	17.0-25.0	21.4-44.6	17.5-24.5	25.6-48.4	12.9-27.1	18.1-29.9	11.2-48.8
HR	0.54		0.44		0.19		2.30
95%CI	0.30-0.97		0.23-0.83		0.08-0.47		0.61-8.77
p (log-rank)	0.034		0.009		<0.001		0.200
p for interaction test					0.002

2 early deaths (less than 3 months) and 1 lost to follow-up before the first time evaluation by MDT.
CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease; ORR, objective response rate; LM, liver metastases; PFS, progression free survival; OS, overall survival; HR, hazard ratio; OR, odds ratio; 95% CI, 95% confidence interval. MDT, multidisciplinary team; NE, not evaluable.