Table 1 –

Patient baseline characteristics

Characteristics	All Patients N=66	Pembrolizumab Monotherapy N=31	Pembrolizumab + Chemotherapy N= 35	pTMB evaluable N= 52	Median pTMB 16.76	Association with pTMB P-valuea
Age
Median	67	68	66	66.5	NA	0.830
Range	47–89	54–89	47–85	47–83	NA
Sex
Male	33	15	18	28	17.24	0.762
Female	33	16	17	24	15.67
Race
White	48	20	28	36	15.67	0.679
Black or African American	15	9	6	13	21.07
Pacific Islander	1	0	1	1	11.34
Other	2	2	0	2	14.85
Smoking Status
Active	14	6	8	10	19.76	0.122
Former	47	23	24	40	15.67
Never	5	2	3	2	6.63
Histology
Adenocarcinoma	54	22	32	42	17.36	0.069
Squamous	7	7	0	6	10.06
Poorly Differentiated	4	1	3	3	25.80
Spindle Cell Neoplasm	1	1	0	1	4.79
ECOG Performance Status at therapy start
0	19	7	12	15	17.24	0.739
1	34	15	19	26	17.85
2	9	8	1	7	17.24
≥ 3	1	1	0	1	9.58
Unknownb	3	0	3	3	13.24
Tissue PD-L1%
<1%	19	0	19	16	21.07	0.325
1–49%	12	0	12	7	11.34
≥ 50%	34	31	3	28	15.67
Unknownb	1	0	1	1	4.49
Number of Metastatic Sites at blood draw
1	6	3	3	3	16.13	0.283
2	29	11	18	19	20.11
3	19	11	8	18	13.67
4	7	3	4	7	13.24
≥ 5	5	3	2	5	17.24
TNM Classification
M1a	12	6	6	8	15.38	0.238
M1b/c	54	25	29	44	17.24

Abbreviations: pTMB, plasma tumor mutation burden.

^aFootnote: Spearman’s rho rank correlation for continuous variables, Wilcoxon rank sum test or Kruskal-Wallis test for categorical variables.

^bPatients for whom this characteristic is unknown were excluded from analysis of the association with pTMB in right-most column.