Table 2.

RCB class distribution by antibiotic use and associations of antibiotics use during immunotherapy with RCB index and pCR, unadjusted and adjusted, Pembrolizumab-4 arm of the I-SPY2 trial, N = 66, 2015–2017

RCB class distribution by antibiotics use
Antibiotics use during IO		RCB class 0	RCB class I	RCB class II	RCB class III	Pb
		N (%)	N (%)	N (%)	N (%)
No		24 (52.2)	8 (17.4)	8 (17.4)	6 (13.0)	0.03
Yes		5 (27.8)	2 (11.1)	10 (55.6)	1 (5.6)
Means; linear regression, outcome = RCB Index
Antibiotics use during IO		N	Mean (std)	Coefficient		P
				(95% CI)a
No		47	1.08 (1.41)	0 (Ref.)
Yes		18	1.80 (1.43)	0.86 (0.20–1.53)		0.01
Antibiotics use during IO	Outcome	N	%	OR (95% CI)		P
				(Outcome = PCR not achieved, unadjusted)
No	No PCR achieved	23	47.9	1 (Ref.)		0.08
	PCR achieved	25	52.1
Yes	No PCR achieved	13	72.2	2.83 (0.87–9.17)
	PCR achieved	5	27.8

^aAdjusted for age at screening for trial, HR status, and stage (II versus III).

^bFisher test.