Table 2. Association Between Broad-Spectrum Antibiotic Use Prior to vs During ICI Therapy and Key Clinicopathologic Features Reflective of Disease Burden and Response.

Characteristic	pATB			cATB
	No	Yes	P Value	No	Yes	P Value
Tumor type			.97			.38
NSCLC	101	6		78	11
Malignant melanoma	32	17		27	40
Other	33	6		22	17
ECOG PS			.09			.84
0-1	138	21		109	55
2-3	22	8		19	11
Stage			.58			.30
Locoregional	28	3		23	8
Metastatic	136	26		103	59
Tumor burden			.07			.73
<2 metastases	124	17		93	48
>2 metastases	40	22		33	19
Age, y			.31			.54
<65	69	15		57	27
>65	97	14		70	41
Response to ICIs			<.001a			.87
Primary progression	66	21		54	33
Objective response	85	5		57	33
ICI course			<.001a			.27
Ongoing	75	4		52	27
Discontinued due to progression	71	24		58	37
Discontinued due to other causes	19	1		16	4
Death while on ICIs			.03a			.61
Yes	12	6		113	63
No	153	23		13	5

Abbreviations: cATB, concurrent antibiotic therapy; ECOG PS, Eastern Cooperative Oncology Group performance status; ICIs, immune checkpoint inhibitors; NSCLC, non–small cell lung cancer; pATB, prior antibiotic therapy.

^aStatistically significant (P < .05).