Patient characteristics, ICI treatment history, symptomatology, and endoscopy findings

Patient	Age	Sex	Malignancy	History of other ICI exposure	ICI type and dose	Days (doses) to onset of symptoms post ICI	Diarrhea grade	Other symptoms	Colitis grade	Endoscopic features	Histopathologic features
1	75	M	Meningioma	None	PembrolizumabDose: 3 mg/kgFrequency: every 3 weeks	39 days (2)	1	None	2	Colonoscopy:Sigmoid colon: localized moderate inflammation characterized by altered vascularity, congestion (edema), friability and granularity	Colonoscopy:- Ileum: mucosa with hyperplastic Peyer’s patches and no diagnostic abnormality- Ascending colon: mucosa with lymphoid aggregate and no diagnostic abnormality- Sigmoid colon: moderately active colitis with neutrophilic cryptitis and crypt abscesses
2	58	F	Colon	- Pembrolizumab (stopped 2 years prior to current ICI): no adverse effects but disease progression	Ipilimumab/NivolumabDose:Ipilimumab-1 mg/kg, Nivolumab- 240 mg (3 mg/kg)Frequency: combined every 6 weeks (4 doses total) followed by nivolumab alone every 2 weeks	8 days (1)	2	Abdominal pain	2	Upper endoscopy:- Gastric antrum: diffuse moderately erythematous mucosa without bleeding- Duodenum: an acquired benign-appearing, intrinsic moderate stenosis in the first portion of the duodenum	Upper endoscopy:- Gastric antrum/fundus/body:active chronic gastritis- Duodenum: mucosa with ulceration, crypt dropout, marked expansion of lamina propria with prominent eosinophils and acute inflammation- Duodenal stricture: mucosa with mild expansion of the lamina propria
3	70	F	Melanoma	- PD-L1 inhibitor (as a part of a clinical trial): for a total of 1 year (stopped 3 years prior to current ICI). No adverse events but disease recurrence- Pembrolizumab: 200 mg 3 (mg/kg) every 3 weeks for total of 8 doses (stopped 1 year prior to current ICI): no adverse events but disease progression	IpilimumabDose: 3 mg/kgFrequency: every 3 weeks	35 days (2)	2	Nausea, vomiting	2	Upper Endoscopy:- Stomach: normal- Duodenum: diffuse moderately scalloped mucosaFlexible Sigmoidoscopy:- Colon: examined portion was normal	Upper Endoscopy:- Duodenum: diffuse active duodenitis with villous blunting, expansion of the lamina propria with mixed inflammation, and reactive epithelial changes- Stomach: antral mucosa with edema and mild patchy inflammationFlexible Sigmoidoscopy:- Colon: normal
4	73	M	Melanoma	Atezolizumab (in combination with cobimetinib): total of 13 cycles (stopped 2 weeks prior to current ICI)	Ipilimumab/NivolumabDose:Ipilimumab-3 mg/kg, Nivolumab-1 mg/kgFrequency: combined every 3 weeks	11 days (1)	2	Nausea, vomiting, abdominal pain	2	Upper Endoscopy:- Stomach: non-bleeding erosive gastropathy- Duodenum: diffuse mildly congested mucosa without active bleedingColonoscopy:- Sigmoid and descending colon: discontinuous areas of nonbleeding ulcerated mucosa with no stigmata of recent bleeding	Upper Endoscopy:- Stomach: active gastritis with small stromal granuloma in antrum. Active gastritis with stromal histiocytes in the body- Duodenum: active duodenitis with villous injuryColonoscopy:- Descending colon: focal active colitis with stromal histiocytes- Colon and sigmoid ulcers: severely active colitis with ulceration
5	79	F	SCC	None	CemiplimabDose: 350 mgFrequency: every 3 weeks	14 (1 dose)	1	Nausea, vomiting	2	Upper Endoscopy:- Stomach: Non-bleeding erosive gastropathy- Duodenum: normalFlexible Sigmoidoscopy:- Colon: Inflammation characterized by congestion (edema), erythema and granularity	Upper Endoscopy:- Stomach: reactive gastropathy and intestinal metaplasia- Duodenum: normalFlexible Sigmoidoscopy:- Colon: mucosa with mildly increased cellularity of the lamina propria and epithelial injury. Focal acute inflammation is also noted, but there is no increase in apoptosis.