PD-L1 expression in non-small cell lung cancer: Correlations with genetic alterations

Figures & data

Figure 1. PD-L1 IHC-staining patterns: expression was noticed in the tumor cells (A), in tumor-associated immune cells (B) or in both cell types (C; white arrow head: PD-L1-positive tumor cells, black arrow heads: PD-L1-positive immune cells). The proportion of positive cells varied with some cases showing few positive cells (A1–C1) while others showed mostly positive cells (A2–C2) (IHC PD-L1, Ab 5H1, 560x).

Figure 2. Tumor-associated PD-L1-positive immune cells stain positive for macrophage marker proteins. PD-L1-positive immune cells (black arrow heads) were encountered in combination with PD-L1-positive tumor cells (A1) or as the only PD-L1-positive cell population (B1). In all cases, PD-L1 was positive in immune cells that were also positive for macrophage marker proteins CD163 (A2, B2) and CD68 (Figs. S1, 2).

Figure 3. PD-L1 IHC positive (+) and negative (–) tumor cells (TC) and immune cells (IC) in pulmonary adenocarcinoma and squamous cells carcinoma. For each subgroup, absolute numbers and relative proportions are indicated. PD-L1-positive ICs are frequent and may occur isolated or in combination with positive TCs.

Table 1. Clinical data of the 436 NSCLC patients.

	Adeno (n = 256)		Squamous (n = 180)
Variables	No. of patients	(%)	No. of patients	(%)
Age
median (range)	65 (38–86)		68 (47–87)
≤ 70	186	72.7	112	62.2
>70	70	27.3	68	37.8
Sex
male	137	53.5	141	78.3
female	119	46.5	39	21.7
Smoking status
ever	227	88.7	178	98.9
never	26	10.2	1	0.6
unknown	3	1.2	1	0.6
UICC stage
I	121	47.3	74	41.1
II	34	13.3	59	32.8
III	84	32.8	42	23.3
IV	17	6.6	5	2.8

Table 2. Summary of PD-L1 protein expression, (A) in the tumor cells (TC) and (B) in tumor-associated immune cells (IC). Cases were classified PD-L1 IHC “positive” if ≥ 1% of the TCs or ICs were stained.

		Adenocarcinomas (n = 256)		Squamous cell carcinomas (n = 180)
		No. of patients	(%)	No. of patients	(%)
A	PD-L1 IHC in tumor cells
	Positive (TCs ≥ 1%)	88	34.4% (88/256)	61	33.9% (61/180)
	Negative (TCs < 1%)	168	65.6% (168/256)	119	66.1% (119/180)
	PD-L1 in tumor cells, proportion of stained cells
	0	168		117
	2 (1–10%)	3	3.4% (3/88)	2	3.3% (2/61)
	3 (10–33%)	8	9.1% (8/88)	4	6.6% (4/61)
	4 (33–66%)	18	20.5% (18/88)	9	14.8% (9/61)
	5 (66–100%)	59	67.0% (59/88)	46	75.4% (46/61)
	PD-L1 in tumor cells, intensity of stained cells
	negative	168		117
	weak	28	31.8% (28/88)	23	34.4% (21/61)
	moderate	42	47.7% (42/88)	31	50.8% (31/61)
	strong	18	20.5% (18/88)	9	14.8% (9/61)
B	PD-L1 IHC in immune cells
	Positive (ICs ≥ 1%)	121	47.3% (121/256)	92	51.1% (92/180)
	Negative (ICs <1%)	135	52.7% (135/256)	88	48.9% (88/180)
	PD-L1 in immune cells proportion of stained cells
	0	112		77
	1 (0–1%)	23		11
	2 (1–10%)	86	71.1% (86/121)	70	76.1% (70/92)
	3 (10–33%)	30	24.8% (30/121)	22	23.9% (22/92)
	4 (33–66%)	5	4.1% (5/121)	0	0.0% (0/92)
	5 (66–100%)	0	0.0% (0/121)	0	0.0% (0/92)

Table 3. In adenocarcinoma PD-L1 expression in TC was found in both early NSCLC (UICC stage I/II) and advanced NSCLC (UICC stage III/IV). Significant associations were found for KRAS, TP53 and STK11 mutations in univariate regression analysis (depicted) and in multivariate analysis (Fig. 4). All other investigated parameters did not show significant associations (Tables S1, 2).

		PD-L1 expression (Tumor cells)
No. of patients (NSCLC-Adeno)		positive	negative	Odds ratio	95% CI	p-value
Patient number	256	88	168
UICC Stage
I / II	155	50	105
III / IV	101	38	63			0.377
KRAS status
wild-type	68	15	53
mutated	55	23	32	2.5	1.2–5.6	0.018
TP53 status
wild-type	66	15	51
mutated	56	23	33	2.4	1.1–5.2	0.029
STK11 status
wild-type	97	34	63
mutated	23	2	21	0.2	0.0–0.8	0.013

Figure 4. Percentage of PD-L1 expression in adenocarcinomas and mutational status of significantly associated genes. The combination of TP53 mutation, KRAS mutation and STK11 wildtype is associated with the highest percentage of PD-L1 expression in adenocarcinoma tumor cells. Conversely, STK11 mutations in the absence of TP53 and KRAS mutations are associated with the lowest percentage.