Table 1 Patient characteristics. Categorical variables are presented as number (percentage). Continuous variables are presented as mean ± standard deviation. Differences between recruitment centres were assessed using Fisher’s exact test, for categorical variables, and one-way ANOVA, for continuous variables. Follow-up samples were collected 2–12 weeks after ICI initiation

N (pre-treatment)

88

14

40

34

-

N (follow-up)

66

11

28

27

-

Sex

 Male

57 (64.8%)

9 (64.3%)

23 (57.5%)

25 (73.5%)

0.35

 Female

31 (35.2%)

5 (35.7%)

17 (42.5%)

9 (26.5%)

Age (years)

60.5 ± 15.0

57.4 ± 14.6

59.4 ± 12.7

66.0 ± 16.8

0.08

BMI (kg/m ² )

28.0 ± 5.4

27.6 ± 5.2

27.6 ± 5.5

28.5 ± 5.4

0.72

BRAF mutant

40 (45.5%)

8 (61.5%)

23 (57.5%)

9 (26.5%)

0.01

LDH (≤ULN)

58 (65.9%)

5 (35.7%)

30 (75.0%)

23 (67.6%)

0.03

Metastatic stage

 Stage III unresectable

2 (2.3%)

1 (7.1%)

1 (2.5%)

0 (0.0%)

2.2 × 10^− 4

 M1a

14 (15.9%)

2 (14.3%)

2 (5.0%)

10 (29.4%)

 M1b

17 (19.3%)

3 (21.4%)

4 (10.0%)

10 (29.4%)

 M1c

32 (36.4%)

6 (42.9%)

14 (35.0%)

12 (35.3%)

 M1d

23 (26.1%)

2 (14.3%)

19 (47.5%)

2 (5.9%)

ECOG performance status

 0

47 (53.4%)

12 (85.7%)

25 (62.5%)

10 (29.4%)

5.9 × 10^− 3

 1

31 (35.2%)

2 (14.3%)

10 (25.0%)

19 (55.9%)

 2

8 (9.1%)

0 (0.0%)

4 (10.0%)

4 (11.8%)

 3

2 (2.3%)

0 (0.0%)

1 (2.5%)

1 (2.9%)

ICI therapy

 Ipilimumab

1 (1.1%)

0 (0.0%)

1 (2.5%)

0 (0.0%)

0.02

 Pembrolizumab

20 (22.7%)

2 (14.3%)

7 (17.5%)

11 (32.4%)

 Nivolumab

30 (34.1%)

5 (37.5%)

20 (50.0%)

5 (14.7%)

 Ipilimumab + Nivolumab

37 (42.0%)

7 (50.0%)

12 (30.0%)

18 (52.9%)

 ORR

49 (55.7%)

9 (64.3%)

21 (52.5%)

19 (55.9%)

0.77

 PFS (months)

5.6 ± 5.3

7.0 ± 9.3

5.3 ± 4.3

5.7 ± 5.0

0.74

 OS (months)

9.0 ± 6.6

3.8 ± 1.4

11.0 ± 7.1

7.8 ± 5.7

0.08