BDNF expression in GISTs predicts poor prognosis when associated with PD-L1 positive tumor-infiltrating lymphocytes

Figures & data

Table 1. Patient and tumor characteristics

Clinicopathological factors		n (%)
Age	≤ 59	132 (53.01)
	> 59	117 (46.99)
Gender	Male	131 (52.61)
	Female	118 (47.39)
Modified NIH criteria	Very low risk	10 (4.02)
	Low risk	83 (33.33)
	Intermediate risk	41 (16.47)
	High risk	115 (46.18)
Tumor size	≤ 5 cm	12 (4.82)
	2–5 cm	93 (37.35)
	5–10 cm	96 (38.55)
	> 10 cm	48 (19.28)
Mitotic figures	≤5	173 (69.48)
	5–10	42(16.87)
	> 10	34 (13.65)
Tumor bleeding	yes	45 (18.07)
	no	204 (81.93)
Ki67 classification	I	180 (72.29)
	II	31 (12.45)
	III	38 (15.26)
R Recurrence	no	199 (79.92)
	yes	50 (20.08)
Serosal invasion	yes	43 (17.27)
	no	206 (82.73)

Figure 1. IHC scores for BDNF expression in tumor tissues from 249 GIST patient

(A) Representative IHC score for BDNF expression in GIST tissues (original magnification: 4× and 20×, round panel and orthogonal panel, respectively. Scale bars, 200 μ m). (B) IHC scoring distribution of BDNF in 249 cases. (C) Statistical analysis of the IHC scoring distribution in patients with different degrees of risk. (D) The concentration of BDNF in the plasma of patients with different NIH degrees of risk was detected by ELISA (43 cases of high risk, 20 cases of intermediate risk and 25 cases of low risk). * p < .05; ** p < .001

Table 2. Correlations between BDNF expression and clinicopathologic features in GIST patients

		Expression of BDNF		p value (χ^2 test)
Clinicopathological feature		Low (n = 140, 56.22%)	High (n = 109, 43.78%)
Age	≤ 59	78	54	0.609
	> 59	65	52
Gender	Male	75	56	0.952
	Female	68	50
Modified NIH criteria	Very low risk	9	1	0.033
	Low risk	53	30
	Intermediate risk	24	17
	High risk	57	58
Tumor size	≤ 5 cm	10	2	0.076
	2–5 cm	59	34
	5–10 cm	49	47
	> 10 cm	25	23
Mitotic figures	≤5	110	63	0.005
	5–10	21	21
	> 10	12	22
Tumor bleeding	yes	22	23	0.200
	no	121	83
Ki67 classification	I	110	70	0.020
	II	19	12
	III	14	24
Recurrence	yes	17	33	< 0.001
	no	126	73
Serosal invasion	yes	23	20	0.566
	no	120	86

Table 3. Univariate analyses of prognostic parameters for survival in patients with gastrointestinal stromal tumor (GIST)

	Univariate analysis
Prognostic parameter	HR	95% CI	p value
Expression of BDNF (High vs Low)	5.455	1.843–16.145	0.002
Age (> 59 vs. ≤ 59)	1.829	0.780–4.287	0.165
Gender (Male vs. Female)	0.516	0.210–1.266	0.148
Modified NIH criteria (High risk vs. Intermediate risk & Low risk & Very low risk)	6.323	1.882–21.242	0.003
Tumor size (> 10 cm vs. ≤ 10 cm)	9.917	4.042–24.335	< 0.001
Mitotic figures (> 5 vs. ≤ 5)	24.800	5.795–106.130	< 0.001
Tumor bleeding (yes vs. no)	0.342	0.080–1.471	0.150
Serosal invasion (yes vs. no)	6.782	2.927–15.716	< 0.001
Recurrence (yes vs. no)	88.361	11.882–657.121	< 0.001
Ki67 classification (III vs. II & I)	2.363	1.493–3.738	< 0.001

Figure 2. Prognostic value of BDNF in GIST patients

(A) Kaplan–Meier curve of overall survival of GIST patients with higher and lower BDNF expression levels (log-rank test, P = .0004). (B) Kaplan–Meier curve of disease-free survival of GIST patients with higher and lower BDNF expression levels (log-rank test, P < .0001). (C) Multivariate Cox regression analysis performed in GIST patients

Figure 3. The sensitivity and specificity of BDNF for GIST prognosis

The ROC curve compares the prognostic accuracy of BDNF with clinicopathological features in all 249 GIST patients by logistic regression. ROC = receiver operating characteristic, AUC = area under the curve. Combined clinical prognostic factors include modified NIH criteria, Ki67 classification, serosal invasion, recurrence, tumor size and mitotic figures

Figure 4. The relationship between BDNF expression and immune checkpoint proteins

(A) Correlation between BDNF and PD-1 expression in 249 patients, (Pearson correlation: r = −0.099, p = .118). (B) Correlation between BDNF and PD-L1 expression in 249 patients, (Pearson correlation: r = 0.254, p < .001). (C) Correlation between BDNF and TIM3 expression in 249 patients, (Pearson correlation: r = −0.103, p = .105). (D) Correlation between BDNF and Galectin 9 expression in 249 patients, (Pearson correlation: r = −0.068, p = .283). (E) Correlation between BDNF and CD3 cell density in 249 patients, (Pearson correlation: r = 0.219, p = .001). (F) Correlation between PD-L1 expression and CD3 cell density in 249 patients, (Pearson correlation: r = 0333, p < .001)

Table 4. Correlations between PD-L1⁺ TIL density and clinicopathologic features in GIST patients

Clinicopathological feature		Expression of BDNF		p value (χ^2 test)
		Low (n = 99, 39.76%)	High (n = 150, 60.24%)
Age	≤ 59	53	79	0.893
	> 59	46	71
Gender	Male	57	74	0.202
	Female	42	76
Modified NIH criteria	Very low risk	7	3	0.040
	Low risk	38	45
	Intermediate risk	11	30
	High risk	43	72
Tumor size	≤ 5 cm	7	5	0.028
	2–5 cm	46	47
	5–10 cm	31	65
	> 10 cm	15	33
Mitotic figures	≤5	67	106	0.872
	5–10	18	24
	> 10	14	20
Tumor bleeding	yes	18	27	0.971
	no	81	123
Ki67 classification	I	74	106	0.775
	II	11	20
	III	14	24
Recurrence	yes	17	33	0.352
	no	82	117
Serosal invasion	yes	21	22	0.181
	no	78	128

Figure 5. Prognostic value of PD-L1⁺ TIL in GIST patients

(A) Kaplan-Meier curve of overall survival of GIST patients with higher and lower PD-L1⁺ expression on TILs (log-rank test, p = .0177). (B) Kaplan-Meier curve of disease-free survival of GIST patients with higher and lower PD-L1⁺ expression on TILs (log-rank test, p = .0129). (C) Multivariate Cox regression analysis performed in GIST patients

Figure 6. Relationship of BDNF expression and PD-L1⁺ expression on TILs with patient survival

(A) High levels of BDNF expression and PD-L1+ expression on TILs predicted worse overall survival than other combinations (log-rank test, p = .0022). (B) High levels of BDNF expression and PD-L1+ expression on TILs predicted worse disease-free survival than other combinations (log-rank test, p = .0004). (C) Combined high BDNF expression and PD-L1+ expression on TILs implied a higher probability of recurrence. (D) Multivariate Cox regression analysis performed in GIST patients. (E) ROC curve comparing the prognostic accuracy of PD-L1 in all 249 GIST patients by logistic regression, as well as BDNF combined with other clinicopathological features