Table 4.

ATF4 expression may predict response to tyrosine kinase inhibitor (TKI) therapy. ATF4 protein level and response rate to TKI according to serum calcitonin levels and RECIST criteria are shown

Variable	Total (n=11)	Response according to calcitonin levels				Response according to RECIST criteria
		PR (n=5)	SD (n=2)	PD (n=4)	p-value	PR (n=2)	SD (n=5)	PD (n=4)	p-value
ATF4 protein, N (%)					0.018				0.05
High	4 (37)	4 (80)	0	0		2 (100)	2 (40)	0 (0)
Low	7 (63)	1 (20)	2 (100)	4 (100)		0 (0)	3 (60)	4 (100)
RET mutation, N (%)
M918T negative	9 (82)	5 (100)	2 (100)	2 (50)	0.127	2 (100)	5 (100)	2 (50)	0.117
M918T positive	2 (18)	0	0	2 (50)		0 (0)	0 (0)	2 (50)

N: total number per variable, PR: partial response, SD: stable disease, PD: progressive disease.