Value Of Serum VEGFA In Predicting The Efficacy Of First-line Chemotherapy And Survival Outcome In Patients With HER2 Negative Advanced Gastric Cancer

Objective:To explore the value of serum vascular endothelial growth factor A（VEGFA）in predicting the efficacy of first-line chemotherapy and survival outcome in patients with human epidermal growth factor receptor 2（HER2）negative advanced gastric cancer（AGC）.Methods:Firstly,we assessed the expression of VEGFA in different human tumors by analyzing the RNA sequencing data downloaded from the Cancer Genome Atlas（TCGA）with the Tumor Immune Estimation Resource 2.0（TIMER 2.0）.The expression levels of VEGFA in gastric cancer tissues and the corresponding matched normal tissues were compared with RNA sequencing data in TCGA database.The minimum P-value approach was used to determine the best cut-off value of VEGFA mRNA expression level,and the samples were divided into high and low expression groups.The survival of patients was compared between the high and low VEGFA mRNA expression groups.The Kaplan-Meier Plotter database was used to analyze the correlation between VEGFA mRNA expression level and the progression free survival（PFS）or overall survival（OS）in patients with AGC.Secondly,82 newly diagnosed patients with HER2 negative AGC admitted to our Hospital from September 2019 to September 2021 were prospectively collected,and 92 non-tumor patients were also included as the control group.The fasting blood samples of patients in the morning at baseline and the indicated time points in the study group were collected,and the serum levels of VEGFA,CEA and CA199 were measured by chemiluminescence method.While fasting blood samples of subjects in the control group before diagnosis were collected,the same procedures of VEGFA detection were followed.Levels of serum VEGFA were compared in patients between the study and control group.The receiver operating characteristic（ROC）curve was used and the area under the curve（AUC）was calculated to determine the ability of baseline VEGFA to alert the AGC.Finally,the correlation between baseline level of serum VEGFA and clinicopathological features of patients with HER2 negative AGC was explored.Complete response（CR）,partial response（PR）,stable disease（SD）evaluated by Response Evaluation Criteria in Solid Tumors（RECIST）Version 1.1,were considered as chemotherapy effective,and progressive disease（PD）was considered as chemotherapy ineffective.The difference in baseline serum VEGFA level between the chemotherapy effective group and the ineffective group was compared.The ROC curve was used and AUC values were calculated to determine the ability of the sole VEGFA,CEA,CA199 and the combinations of each indicator in predicting chemotherapy ineffectiveness.The logistic regression analysis was used to select the independent predictors of chemotherapy efficacy.Then the dynamic changes of serum VEGFA before and after treatment were analyzed.The best cut-off value of the serum VEGFA related to patient survival was determined by X-tile software.And patients were divided into high and low expression groups based on the best cut-off value.Kaplan-Meier survival analysis was used to analyze the differences in PFS and OS between the two groups.The differences of PFS and OS were analyzed by Kaplan-Meier survival analysis.The Cox regression analysis was used to determine the independent predictors of PFS and OS.Results:The RNA sequencing data downloaded from TCGA and analyzed by TIMER2.0 revealed that the expression of VEGFA mRNA was significantly higher in gastric cancer（STAD）tissues（n=415）than in normal tissues（n=35）（p<0.001）.Meanwhile,the expression of VEGFA mRNA was also showed to be significantly higher in breast cancer（BRCA）,cholangiocarcinoma（CHOL）,esophageal cancer（ESCA）,colon cancer（COAD）,hepatocellular liver cancer（LIHC）,thyroid cancer（THCA）,rectal 5 adenocarcinoma（READ）,prostate cancer（PRAD）and other tumor tissues than in the corresponding normal tissues.The results indicated that VEGFA was aberrantly overexpressed in a variety of tumors.TCGA data further unraveled that the expression level of VEGFA mRNA in gastric cancer tissues were significantly higher than in their corresponding paired normal gastric tissues（n=27,P=0.0025）.In TCGA database,the OS in patients with higher VEGFA mRNA expression was shorter（n=40）than those with lower expression（n=231）,but the difference was not of statistical significance（P=0.089）.However,in Kaplan-Meier Plotter database,when compared to patients with lower VEGFA expression（n=66）,patients with higher VEGFA expression（n=34）exhibited significantly shorter PFS（HR=2.08,P=0.0018）.In the meantime,patients with higher VEGFA expression（n=36）also showed significantly shorter OS（HR=1.85,P=0.0082）than those with lower expression level（n=66）.Our cohort analyses results showed that the baseline serum level of VEGFA was significantly higher in HER2 negative patients with AGC than in non-tumor patients（Z=-7.004,P<0.001）.When the optimal cut-off value of baseline serum VEGFA was set as 129.63 pg/ml,the AUC of ROC curve for the ability of VEGFA to alert HER2 negative AGC occurrence was 0.808（95%CI:0.742-0.874,P<0.001）.The baseline serum level of VEGFA was found to be associated with either eastern cooperative oncology group performance status（ECOG PS）（Z=-2.357,P=0.018）,or malignant serous cavity effusion status at diagnosis（Z=-3.041,P=0.002）by clinical characteristics analyses.For chemotherapeutic efficacy analyses in HER2 negative AGC patients,the baseline serum level of VEGFA was found to be lower in the effective group than in the ineffective group（Z=-5.162,P<0.001）.The AUC of the ROC curve was 0.856（95%CI:0.777-0.935,P<0.001）,and baseline VEGFA showed stronger power to predict first-line treatment ineffectiveness when compared to either the baseline CEA（AUC:0.575）or the baseline CA199（AUC:0.697）.Furthermore,it is not surprising that detection of combined VEGFA and CEA and CA199 can provide the best ability in predicting first-line treatment ineffectiveness（AUC:0.858）,while the combined detection of VEGFA and CEA（AUC:0.856）,VEGFA and CA199（AUC:0.854）,or CEA and CA199（AUC:0.688）showed predictive values with varying degrees.Univariate and multivariate logistic regression analyses showed that the baseline serum VEGFA level was an independent predictor of first-line chemotherapy efficacy in patients with AGC（OR:26.244,95%CI:5.286-130.302,P<0.001）.In dynamic analyses in patients with HER2 negative AGC,the level of serum VEGFA after 2 cycles of treatment was lower than that at baseline,the difference was statistically significant（n=59,Z=-2.308,P=0.021）.But there was no significant difference in serum VEGFA level between baseline and 2 cycles after treatment,in either the effective group（n=42,Z=-1.626,P=0.104）,or the ineffective group（n=17,Z=-1.655,P=0.098）.With 137.60 pg/ml setting as the best cut-off value for the baseline serum VEGFA,PFS was significantly prolonged in patients with low expression than that with high expression（7.4 months vs.2.5 months,P<0.001）.By the end of follow-up,while the best cut-off value for the baseline serum VEGFA was set as 169.80 pg/ml,the median OS of patients in the high expression group was 9.3 months（95%CI:1.706-16.834）,and patients in the low expression group did not reach the OS endpoint.Univariate and multivariate Cox regression analyses showed that the baseline serum VEGFA level was an independent predictor in HER2 negative AGC patients for PFS（HR:3.152,95%CI:1.657-5.996,P<0.001）,but not yet for OS（HR:2.088,95%CI:0.998-4.371,P=0.051）.Conclusion:Detection of the baseline serum level of VEGFA has the potential to alert the occurrence of HER2 negative AGC.The baseline serum VEGFA level in patients with HER2 negative AGC is associated with patients’ important clinicopathological characteristics.It may serve as an independent predictor for patients with AGC in predicting the efficacy of first-line chemotherapy and the PFS,but not the OS.