Table 3

Patient characteristics at start of ICI

	Anti-CTLA-4 (n=596)				Anti-PD-1 (n=239)				All (N=835)
	No preceding RT		Preceding RT		No preceding RT		Preceding RT		No preceding RT		Preceding RT
	n	%	n	%	n	%	n	%	n	%	n	%
Total	446	100	150	100	154	100	85	100	600	100	235	100
Age (years), mean±SD	62.7 (±13.1)		57.8 (±14.6)		59.1 (±14.6)		58.2 (±14.1)		61.8 (±13.6)		57.9 (±14.4)
Sex
Male	265	59.4	93	62.0	88	57.1	51	60.0	353	58.8	144	61.3
Female	181	40.6	57	38.0	66	42.9	34	40.0	247	41.2	91	38.8
Primary site
Skin	332	74.4	109	72.7	112	72.7	63	74.1	444	74.0	172	73.2
Occult (MUP)	43	9.6	28	18.7	21	13.6	10	11.8	64	10.7	38	16.2
Mucosa	37	8.3	6	4.0	17	11.1	8	9.4	54	9.0	14	6.0
Uvea	32	7.2	6	4.0	3	2.0	3	3.5	35	5.8	9	3.8
Missing data	2	0.5	1	0.6	1	0.6	1	1.2	3	0.5	2	0.8
BRAF V600 mutational status
Wild type	267	59.9	75	50.0	108	70.1	52	61.2	375	62.5	127	54.0
Mutation	135	30.3	55	36.7	36	23.4	29	34.1	171	28.5	84	35.7
Missing data	44	9.8	20	13.3	10	6.5	4	4.7	54	9.0	24	10.3
Overall performance status
ECOG=0	167	37.4	38	25.3	74	48.1	27	31.8	241	40.2	65	27.7
ECOG≥1	83	18.6	39	26.0	36	23.4	28	32.9	119	19.8	67	28.5
Missing data	196	43.9	73	48.7	44	28.6	30	35.3	240	40.0	103	43.8
Serum LDH
Normal	173	38.8	55	36.7	64	41.6	27	31.8	237	39.5	82	34.9
Elevated ≤twofold ULN	132	29.6	52	34.7	49	31.8	33	38.8	181	30.2	85	36.2
Elevated >twofold ULN	64	14.3	24	16.0	26	16.9	13	15.3	90	15.0	37	15.7
Missing data	77	17.3	19	12.6	15	9.7	12	14.0	92	15.3	31	13.2
M stage
M1a (skin, lymph node)	71	15.9	5	3.3	16	10.4	4	4.7	87	14.5	9	3.8
M1b (lung)	110	24.7	16	10.7	45	29.2	9	10.6	155	25.8	25	10.6
M1c (other organ)	185	41.5	39	26.0	77	50.0	23	27.1	262	43.7	62	26.4
M1d (brain)	71	16.0	89	59.3	15	9.8	48	56.5	86	14.3	137	58.3
Missing data	9	2.0	1	0.7	1	0.6	1	1.1	10	1.7	2	0.9
Bone metastases
No	377	84.5	103	68.7	140	90.9	56	65.9	517	86.2	159	67.7
Yes	69	15.5	47	31.3	14	9.1	29	34.1	83	13.8	76	32.3
Missing data	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
Number of organ sites involved
≤3	343	76.9	87	58.0	111	72.1	40	47.1	454	75.7	127	54.0
>3	94	20.1	62	41.3	42	27.3	44	51.8	136	22.7	106	45.1
Missing data	9	2.0	1	0.7	1	0.6	1	1.1	10	1.7	2	0.9
Systemic pretreatment in stage IV
No	138	30.9	27	18.0	28	18.2	11	13.0	166	27.7	38	16.2
Yes	291	65.2	123	82.0	123	79.8	72	84.7	414	69.0	195	83.0
Missing data	17	3.9	0	0.0	3	2.0	2	2.3	20	3.3	2	0.8
Duration of stage IV disease at start of ICI (months) Median (p10; p90)	6.0 (0.8; 26.6)		9.8 (2.2; 42.4)		13.7 (1.4; 36.2)		14.2 (2.5; 43.8)		8.2 (1.4; 26.5)		14.7 (4.5; 68.2)

The given patient characteristics refer to the start of the investigated ICI therapy. Percentages are given per column for each individual patient cohort. M stage categories refer to the AJCC v8 classification system; the number of organ sites refer to organs involved with metastasis; systemic pretreatment describes systemic therapies received by the patient for inoperable stage IV disease (not adjuvant) prior to the investigated ICI therapy.
BRAF, v-raf murine sarcoma viral oncogene homolog B1; ECOG, Eastern Cooperative Oncology Group; ICI, immune checkpoint inhibition; LDH, lactate dehydrogenase; MUP, melanoma of unknown primary; p10, 10th percentile; p90, 90th percentile.; RT, radiotherapy; ULN, upper limit of normal.