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Leptomeningeal metastases (LMs) are highly invasive which leads to poor prognosis, but the accurate diagnosis of LM is challenging. It is necessary to investigate more advanced diagnostic methods to realize precision medicine. The main purpose of this study was to select a more effective method for the auxiliary diagnosis of LM by comparing various detection methods. The secondary purpose was to explore the value of cerebrospinal fluid (CSF) tumor markers (TMs) and circulating tumor DNA (ctDNA) testing in guiding clinical treatment.TMs in serum and CSF of patients were detected by chemiluminescence. The ctDNA of CSF and plasma were detected by the next-generation sequencing (NGS) technology.In total, 54 tumor patients participated in this study, in which 39 with LM and 15 without LM (8 with parenchymal tumor and 7 without brain metastasis). The results showed that the sensitivity and accuracy of CSF cytology isolated during the first lumbar puncture were 0.31 (95% CI 0.17-0.48) and 0.50 (95% CI 0.36-0.64), respectively. The sensitivity and accuracy of CSF_CEA were 0.71 (95% CI 0.54-0.85) and 0.78 (95% CI 0.64-0.89), which were better than those of CSF_NSE and CSF_CFRA-211. The sensitivity and accuracy of CSF_ctDNA were 0.92 (95% CI 0.79-0.98) and 0.91 (95% CI 0.80-0.97), significantly higher than that of CSF cytology (P 0.01). The sensitivity and accuracy of CSF_CEA combined with CSF_ctDNA were 0.97 (95% CI, 0.87-1.00) and 0.94 (95% CI 0.85-0.99), which were significantly higher than the traditional methods CSF cytology (P 0.01). For LM patients with hydrocephalus, the sensitivity of CSF ctDNA even achieved 100% (14/14).CSF_CEA combined with CSF_ctDNA could be used to accurately distinguish patients with LM from those with no brain metastasis and from those with parenchymal tumors. CSF_ctDNA testing reveals a unique mutation profile for patients with LM. Dynamic detection of CSF TM and ctDNA can better predict the efficacy and reveal the cause of drug resistance to guide subsequent treatment.Clinical trial registration number: NCT03029065.

Tumor metastasis is a series of complicated biological events. Hematogenous metastasis mediated by von Willebrand factor (vWF) is critical in tumor metastasis. However, the source of vWF and its role in tumor metastasis are controversial, and the further mechanism involved in mediating tumor metastasis is still unclear. In this study, we first demonstrated that lung adenocarcinoma cells could express vWF de novo and promotes tumor metastasis. Through the analysis of transcriptome sequencing, the metastasis promotion effect of vWF may be related to phosphorylase kinase subunit G1 (PHKG1), a catalytic subtype of phosphorylase kinase (PhK). PHKG1 was highly expressed in lung adenocarcinoma patients and led to poor prognosis. Further experiments found that lung adenocarcinoma-derived vWF induced the upregulation of PHKG1 through the PI3K/AKT pathway to promote glycogenolysis. Glycogen was funneled into glycolysis, leading to increased metastasis. Tumor metastasis assayed in vitro and in vivo showed that knockdown of PHKG1 or synergistic injection of phosphorylase inhibition based on the overexpression of vWF could inhibit metastasis. In summary, our research proved that lung adenocarcinoma-derived vWF may mediate tumor metastasis by regulating PHKG1 to promote glycogen metabolism and suggested potential targets for inhibition of lung adenocarcinoma metastasis.

The incidence of lung cancer tends to be younger, and adenocarcinoma is the main histological type. Even patients with the same tumor type may have significant differences in clinical features, tumor microenvironment and genomic background at different ages. Immune checkpoint inhibitors (ICIs) have been shown to improve clinical outcomes in patients with lung adenocarcinoma (LUAD). However, differences in ICI efficacy between older and younger patients are unknown. Our study aimed to explore the relationship between age and immunotherapy in LUAD.In our study, 1313 resected LUAD patients in our hospital were divided into young (age ≤ 50) and old groups (age 50), and the clinical characteristic differences between them were analyzed. Of these, next-generation sequencing (NGS) was performed on the 311 cases. In addition, immune-related signatures of 508 LUAD patients were analyzed by TCGA RNA expression data. Then, we validated genomic and clinical information of 270 LUAD samples in the MSKCC cohort.ERBB2 and EGFR gene mutations were significantly different between the two groups, and the gene mutation number in the old group was significantly higher than that in the young group. In addition, immune-related signatures of LUAD patients were analyzed by TCGA RNA expression data, which indicated that the patients in the old group might have a better immune microenvironment. Then, we validated the MSKCC cohort and found that the TMB of the old group was significantly higher than that of the young group, and the OS of immunotherapy was longer in the old group.Our study was the first to analyze the differences in the genomic landscape and immune-related biomarkers between the young and old groups of LUAD patients and found that the old group had a better efficacy of immunotherapy, providing a reference for the study design and treatment of patients with LUAD.

Lung cancer remains the most common malignancies and the leading cause of mortality worldwide, more than 80% of which are Non–Small-Cell Lung Cancer (NSCLC). For approximately one-third of diagnosed NSCLCs with stage I–IIIA disease, surgical resection is recommended as a preferred curative treatment. Nevertheless, many resected NSCLC patients experience recurrence. The adjuvant treatment option of patients with resected Non–Small-Cell Lung Cancer (NSCLC) remains unstandardized. At present, there are many postoperative adjuvant therapy options for resected NSCLC, including chemotherapy, targeted therapy, chemotherapy and immunotherapy. However, which adjuvant therapy is better for which patients is remaining to be explored. With further development of ctDNA-based molecular residual disease (MRD) research, more accurate clinical trials may be needed in the future to refine more comparison of biomarker for more precise treatment in postoperative adjuvant therapy in the future. In our manuscript, we discussed the status of possible markers and possible future clinical trials in combination with MRD. Finer patient stratification and adjuvant treatment options need to be further explored.

Von Willebrand factor (VWF), a large glycoprotein with hemostatic properties, is mainly synthesized by megakaryocytes and endothelial cells (ECs). In recent years, studies have found that tumor cells also can produce VWF de novo. Tumor growth is usually accompanied by hypoxic environment, and whether hypoxia will influence von Willebrand factor production in tumor cells is still unknown. In this research, we demonstrated that hypoxia could induce the production of VWF in breast cancer cells (MCF-7 and MDA-MB-231 cell lines), and promoted cell migration as well as angiogenesis. Notably, VWF is a key factor for hypoxia to promote breast cancer cell migration and angiogenesis, and knocking down VWF can attenuate the effects of hypoxia. Further study was conducted on the molecular mechanism to clarify why hypoxia can promote VWF synthesis in breast cancer cells. We found that Yin-Yang 1 (YY1, a transcription factor) had a binding site to the promoter region of VWF, and acted as a transcriptional activator of VWF. Meanwhile, hsa-miR-424 inhibited VWF production by associating with the 3'-UTR of VWF mRNA. Here, we proved that hypoxia up-regulated the transcription factor YY1 and down-regulated hsa-miR-424 to increase the expression level of VWF. Additionally, knockdown of transcription factor YY1 and transfection of hsa-miR-424 mimics had a synergistic effect in reducing hypoxia-induced VWF production of breast cancer cells, cell migration and angiogenesis in vitro.

Background: Anaplastic lymphoma kinase (ALK) fusion, an important driven oncogene mutation, occurrs in 3%~7% non-small cell lung cancers (NSCLC), and EML4 is the most common partner gene. With the widespread application of next-generation sequencing (NGS), more gene breakpoint fusions have been discovered, and functional fusion transcripts can bring targeted clinical benefits. Clinical trials have shown that NSCLC patients with ALK fusion can obtain significant survival benefits through ALK tyrosine kinase inhibitor (ALK-TKI) treatment. In our case, a novel CLHC1/RNT4 intergenic region- ALK fusion was identified for the first time in a LUAD patient with BM, and the patient benefited from endostar and crizotinib sequential alectinib. Our case suggested the advantages of NGS for fusion detection and provided promising treatment options for NSCLC patients with BM harboring ALK fusions.

Clear cell meningioma (CCM), an unusual subtype of World Health Organization (WHO) grade II meningioma, represents only 0.2– 0.8% of meningiomas. Spinal CCMs are even rarer with unique clinical features: more common in younger patients; more likely to appear in lumbar spine; high recurrence rate. Although surgery and radiotherapy are the most common treatment for primary tumors and disease recurrence, there are lack of treatment options for recurrent or metastasis disease. It is urgent need to explore new effective treatment method. In our case, we firstly reported a rare spinal CCM patient with PD-L1 positive and multiple metastases benefiting from PD-1 inhibitor plus anti- angiogenesis therapy. This treatment program is effective, safe, and has a strong therapeutic reference value, which provides promising treatment options and the direction of future clinical trials for spinal CCMs.

Malignant gliomas are the most common brain tumors, with generally dismal prognosis, early clinical deterioration and high mortality. Recently, 2-aminoquinoline scaffold derivatives have shown pronounced activity in central nervous system disorders. We herein reported a series of 2-aminoquinoline-3-carboxamides as novel non-alkylator anti-glioblastoma agents. The synthesized compounds showed comparable activity to cisplatin against glioblastoma cell line U87 MG in vitro. Among them, we found that 6a displayed good inhibitory activity against A172 and U118 MG glioblastoma cell lines and induced cell cycle arrest in the G2/M phase and apoptosis in U87 MG by flow cytometry analysis. Additionally, 6a displayed low cytotoxicity to several normal human cell lines. In silico study showed 6a had promising physicochemical properties and was predicted to cross the blood-brain barrier. Moreover, preliminary structure-activity relationships are also investigated, shedding light on further modifications towards more potent agents on this series of compounds. Our results suggest this compound has a promising potential as an anti-glioblastoma agent with a differential effect between tumor and non-malignant cells.

e21011 Background: EGFR exon 20 mutations are associated with acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). EGFR exon 20 mutations are usually not present alone, suggesting a more complex subtype of exon 20 mutations. Methods: In this study, we retrospectively analyzed the different subtypes and compound mutation profiles of EGFR 20 mutations. A total of 1,233 NSCLC patients’ tumors were collected and the mutations were detected by next-generation sequencing (NGS) from May 2020 to June 2021. Results: A total of 415 NSCLC patients' tumors harbored EGFR exon 20 mutations, accounting for 33.66% of the entire EGFR mutation cohort. Among these 415 patients, most of mutations were single-nucleotide variant (SNV) (379; 91.33%), and a few were indel or insertion mutations (39; 9.40%). The insertions were all in the back of exon 20, which were resistant to EGFR-TKIs. In addition, the subtypes of SNV were concentrated in T790M (270; 71.24%), S768I (48; 12.66%) and C797S (33; 8.71%), and all T790M mutations were accompanied by other mutations. Notably, the compound mutations of exon 20 have also been analyzed in this study. EGFR exon 20 combined with other EGFR mutations were detected in 345 patients. The compound mutations of exon 20-18, exon 20-19, exon 20-20 and exon 20-21 were detected in tumors from 52 (15.07%), 163 (47.25%), 43 (12.46%) and 140 (40.58%) patients respectively. Remarkably, the compound mutation subtype of exon 20-20 was T790M/C797X (29; 67.55%) and exon 20-21 was T790M/L858R (124; 88.57%). Conclusions: Diverse patterns of SNV mutations are seen in EGFR exon 20 mutations tumors. EGFR 20 mutations often accompany other mutations, which are associated with resistance to EGFR-TKIs. These data may help avoid the resistance of future adjuvant targeted therapy.

4025 Background: B7-H6, also known as NCR3LG1, is a promising molecule in B7 family and a ligand of natural killer (NK) -cell-activating receptor NKp30. B7-H6 can bind NKp30 and induce NK activation and cytokine secretion to exert anti-tumor effects. Studies have reported that the B7-H6 expression is significantly correlated with post-operative prognosis and distant metastasis status in patients with cancer. In patients with gastric cancer, B7-H6 high expression is significantly associated with longer OS. However, the effects of B7-H6 on immunotherapy and immune microenvironment are unknown. Herein, we used the data from TCGA database of gastric cancer to analyze the influence of B7-H6 expression on immune microenvironment. Methods: The gene expression profile and clinical data in gastric cancer were extracted from TCGA database ( http://cancergenome.nih.gov ). According to the previous reported article, 15 was chosen as the cutoff value for the expression of B7-H6, and the expression of B7-H6 is divided into two groups, high group (B7-H6 expression＞15) and low group (B7-H6 expression≤15). Kaplan-Meier analysis was used to verify the influence of B7-H6 expression on OS prognosis. “Cell Type Identification by Estimating Relative Subsets of RNA Transcripts” (CIBERSORT) algorithm was used to analyze the proportion of immune-related cells in the two groups. “Estimation of STromal and Immune cells in Malignant Tumours using Expression data” (ESTIMATE) algorithm was used to analyze stromal and immune scores in the two groups. The differences of immune-related signatures between the two groups were calculated according to previous reports. Results: Kaplan-Meier survival analysis showed that high group was significantly associated with longer overall survival (p value = 0.016), which was consistent with previous reports. The result of CIBERSORT algorithm showed that the proportion of activation immune correlation CD8(+) T cells and NK active cells was significantly higher in low group than in high group (p＜0.05). Meanwhile, the proportion of immune suppressive correlation CD4 resting memory T cell was significantly lower in low group than in high group (p＜0.05). The result of ESTIMATE algorithm showed that the stromal score, immune score, and ESTIMATE score in low group were significantly higher than in high group (p＜0.01). The immune-related signatures, including immune signature, expanded immune signature, TLS signature, myeloid cell chemotaxis, tertiary lymphoid structure, were significantly higher in low group than in high group (p＜0.05). Conclusions: The low B7-H6 expression was correlated with better immune microenvironment. The effect of B7-H6 expression on immunotherapy needs to be further explored.

e20544 Background: Lung adenocarcinomas (LUAD) is the most common histological subtype of lung cancers. Immunotherapies (ICIs) have been confirmed to improve the clinical outcomes of LUAD patients. Efficacies of ICIs are considered strongly associated with tumor immune microenvironments (TIME). Age-related immune dysfunction might induce difference on the efficacy of ICIs between younger and older patients. However, the potential effect of age on TIME remains little known and controversial. Herein, we aimed to analysis the association between age and TIME based on The Cancer Genome Atlas (TCGA) database. Methods: We screened out 582 LUAD patients with complete information, whose tumors underwent next-generation sequencing (NGS) detection in TCGA. All patients were divided into two groups according to age, the younger group (age < 50-year old) and the older group (age≥50-year old). The differences of immune-related signatures between the two groups were calculated according to previous reports. We also analyzed the differences in immune-related signature between different clinical stages. P-values were calculated via the T.Test. Results: In total 582 patients with LUAD in our study, 115 (19.76%) patients in younger group and 467 (80.24%) patients in older group were found. Many immune-related signatures were found significantly higher in older group than in younger group, including cytolytic activity (CYT) (p = 0.0352), expanded immune signature (p = 0.0065), T cell inflamed gene expression profile (GEP) (p = 0.0048), IFN-γ-related response genes (p = 0.0346), immune signature (p = 0.0022), immunosuppression (p = 0.0065), major histocompatibility complex class I (MHC class I) (p = 0.0319), T-cell survival (p = 0.0235), tertiary lymphoid structures (TLS) signature (p = 0.0001) and total_TILs_scores (p = 0.0020). In addition, tertiary lymphoid structure (p = 0.0355) and TLS_signature (p = 0.0243) were found significantly difference in different clinical staging, which decreased as the staging get later. On the contrary, cell cycle score (p = 0.0001) increased as the staging get later. Conclusions: Our study evaluated the impact of age and clinical stage on the TIME in patients with LUAD using a threshold of 50 years old for the first time. We founded that LUAD patients in older group had better TIME than in younger group and some immune-related signatures were significantly related with clinical staging.

e22527 Background: Li-Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome, mainly caused by the lack of tumor suppressor gene TP53. The LFS related tumors include breast cancer, brain tumors, malignant sarcoma, bone cancer and central nervous system tumors. In addition to TP53 germline mutations, studies have shown that CHEK2 is also a susceptibility gene for LFS, and CHEK2 germline mutations is related to a series of cancer types. However, the correlation between tumor mutation burden (TMB), age, gender, PD-L1 expression and TP53 or CHEK2 germline mutations in malignant tumors remains unknown. Methods: In this study, we retrospectively analyzed the mutation characteristics of TP53 or CHEK2 germline mutations in patients with solid tumors without selecting age or family history. We identified 631 patients harboring TP53 or CHEK2 mutations from 9337 patients with malignant solid tumors. According to the ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity, the 631 patients in the retrospective cohort were divided into three groups, including P/LP group (with pathogenic or likely-pathogenic mutations), VUS group (with uncertain significance mutations) and B/LB group (with benign or likely-benign mutations). We also analyzed the differences in TMB, age, gender and PD-L1 expression among the three groups. Statistical significance was defined as P-value less than 0.05. Results: The 631 (631/9337) patients carried TP53 or CHEK2 germline mutations were identified, in which 33 patients with pathogenic mutations and 15 patients with likely-pathogenic mutations. These pathogenic or likely-pathogenic mutations mainly occurred in lung cancer, brain tumors, colorectal cancer and liver cancer, accounting for about 35.4%, 20.8%, 16.7% and 12.5%, respectively. Among the three groups, TMB was significantly different between P/LP group and B/LB group (P = 0.037), and the B/LB group was higher. In addition, we found that the three groups had no significant differences in age, gender and PD-L1 expression. Conclusions: Our data showed that 0.823% (48/8535) malignant solid tumor patients carried TP53 (28/48) or CHEK2 (20/48) germline pathogenic or likely_ pathogenic mutations. In addition, the TMB value in B/LB group was significantly higher than that in P/LP group. The other characteristics of LFS will be studied in the future.

e14028 Background: Epidermal growth factor receptor (EGFR), a trans-membrane receptor tyrosine kinase, consists of an extracellular ligand-binding domain (ECD), a single transmembrane domain (STMD) and an intracellular kinase domain (ICD). Glioma is the most common primary brain tumor, and variations of EGFR are frequently reported in glioma patients. This study aimed to analysis the landscape of EGFR mutation subtype in Chinese patients with glioma. Methods: We retrospectively collected 1779 patients with glioma. In all patients enrolled, the comprehensive genomic profiling containing EGFR gene was detected using tumor tissue, including WES, 539 tumor related-gene panel or 131+4 gene panel (Simceredx). And the somatic mutations including SNV, INDEL, CNV, fusion were analyzed correspondingly. Results: Among 1779 patients with glioma, EGFR mutations were identified in 392 (22.03%) patients. The age was significantly higher in patients with EGFR-mutant group than in patients without EGFR-mutant group, with median age 54 vs. 45 (p = 4.81e-19). The sex didn’t reach statistical significance in two group. The incidence rate of different EGFR mutation types among all patients with EGFR-mutant were amplification (314,80.10%), SNV(198,50.51%), Indel(24,6.12%) and fusion(44,11.22%) respectively. 162 (46.69%) had two or more mutation types simultaneously. The main partner gene of EGFR fusion was LOC100996654, followed by ELDR and SEC61G, and the main EGFR breakpoints were in intron24, intron7, exon7. Within 347 SNV and Indel mutations, exon7, 15, 20, 6 and 8 were detected in 103(29.68%), 50(14.41%), 28 (8.07%), 25(7.20%) and 18 (5.19%) respectively. The top three mutaton subtypes within exon7 were account for 19.31%, which included p.A289V,p.A289T,p.T263P. Meanwhile, the mutation frequency within ICD encoded by exons 18-24 was 17.00%, in which exon20 mostly distributed (8%). In exon20, the most common mutation subtypes were p.V774M,p.H773dup,p.T790M, while in the second proportion exon18 (3.46%), the main subtype were p.G719A/D. Conclusions: EGFR amplification was the most common mutation type. There were 122 SNV and Indel subtypes altogether and occurred throughout almost the entire exon region, in which exon7 contained maximum 21 different subtypes and the p.A289V was the main type. The distribution of subtypes in ECD were much more than in ICD. The relationship between subtypes occurrence and cancer will be further studied in the future.

The metastasis and angiogenesis of breast cancer has always been a difficult problem for treatment. It has recently been discovered that Von Willebrand Factor (vWF), in addition to hemostasis, also plays a role in tumor metastasis and angiogenesis. We noticed that besides endothelial cells, breast cancer cells (MDA-MB-231 and MCF-7) could also express vWF. In vitro experiments showed that knocking down vWF inhibited breast cancer cell metastasis. And we found that overexpression of vWF significantly promoted VEGF-A-dependent vascular proliferation in vitro by activating the PI3K/Akt signaling pathway. Further studies indicated that inhibition of PI3K/Akt signaling pathway up-regulated the expression of miR-205-5p, and miR-205-5p could bind to the 3'UTR region of VEGF-A to hinder the production of VEGF-A. Furthermore, when a spontaneous lung metastasis model was established in Balb/c female mice, knockdown of vWF in 4 T1 cells resulted in a decrease in tumor blood vessel density and effectively inhibited lung metastasis, accompanied by a decrease in the expression level of VEGF-A and an increase in the expression level of miR-205-5p. In summary, our findings provide experimental evidence that overexpression of vWF in breast cancer cells down-regulates the expression of miR-205-5p and up-regulates the expression of VEGF-A through the PI3K/Akt signaling pathway, thereby promoting tumor angiogenesis and metastasis.

Peritoneal metastasis of colorectal cancer is one of the most incident and fateful diseases among relapse cases. It shows a certain resistance to systemic chemotherapy. The perfusion system in clinic is complex and hard to be used in fundamental researches. This study aims at evaluating the effect of an improved hyperthermic intraperitoneal chemotherapy with Raltitrexed used in tumor-bearing mice with peritoneal metastatic colorectal carcinoma. The results showed that no severe adverse effect was observed. All control animals developed extensive peritoneal and mesenteric metastatic nodes. Tumor sites in the treatment groups were reduced significantly. The administration dose of Raltitrexed influenced concentration in systemic blood and peritoneal tissues. Temperature promoted the intracellular absorption of Raltitrexed significantly. Our findings reveal that hyperthermic intraperitoneal chemotherapy is an efficient therapy in treating peritoneal metastatic carcinoma in nude mice. It can effectively reduce the extension of carcinoma cells from macro and micro examination. The combination of hyperthermia and Raltitrexed resulted in an improved therapeutic effect on animal models.

Background: Human polypyrimidine tract binding protein 3 (PTBP3) was first discovered in 1999 and has been well characterised as a differentiation regulator. However, its role in human cancer has rarely been reported. Our previous study revealed increased PTBP3 protein level in gastric cancer tissues. Downregulation of PTBP3 suppressed the proliferation and differentiation of gastric cancer cells in vivo. Methods: PTBP3 mRNA levels in human gastric cancer and adjuvant non-tumour tissues were detected. Apoptosis and 5-FU effect were determined in PTBP3-silenced gastric cancer cells. Underlying molecular mechanisms were investigated. Results: MRNA expression of PTBP3 was upregulated in gastric cancer tissues, especially in those at an advanced stage. PTBP3 silencing led to apoptosis, under which modulation of PTB and thereby switch of Bcl-x pre-mRNA splicing pattern might be an important mechanism. Further research found that inhibition of PTBP3 expression enhanced the chemosensitivity of gastric cancer cells towards 5-FU treatment. This was mediated by reduced expression of histone deacetylase 6 (HDAC6), which further inhibited the phosphorylation of Akt and the expression of thymidylate synthase (TYMS), the critical determinant of 5-FU cytotoxicity. Conclusions: PTBP3 might serve as a biomarker of gastric cancer or potential target for anti-cancer therapy.

e21059 Background: Anaplastic lymphoma kinase ( ALK), c-ros oncogene 1 receptor tyrosine kinase ( ROS1), ret proto-oncogene ( RET) and neurotrophic receptor kinase ( NTRK) are important driver genes in lung cancer. Each of these four genes fusions as therapeutic targets have been recommended by the national comprehensive cancer network (NCCN) guidelines for non-small cell lung cancer (NSCLC). Malignant pleural effusion (MPE) is observed in multy types of malignancies, especially in lung cancer. Studies have indicated that next generation sequencing (NGS) detection of somatic mutations by MPE is reliable. Nevertheless, the distribution and comparison of fusions in lung cancer between malignant pleural effusion and tumor tissue specimen have not been well characterized yet. Methods: In this study, 9-gene, 69-gene and 539-gene panel NGS profiling were performed by MPE and tumor tissue in 640 and 10013 patients with lung cancer respectively. The variation analysis between patients with or without gene fusion in different sample groups were calculated by fisher exact test via SPSS v26.0. Results: In lung cancer patients using MPE detection, 59 of 640 (9.22%) were found harboring at least one of the four gene fusions, and the ratio of ALK, ROS1, RET and NTRK fusion was 6.25% (40/640), 1.41% (9/640), 0.63% (4/640) and 0.47% (3/640) respectively. Meanwhile, we found gene fusions in 6.25% (626/10013) lung cancer patients using tumor tissue detection, including 3.66% (366/10013) ALK fusion, 1.07% (107/10013) ROS1 fusion, 1.09% (108/10013) RET fusion and 0.22% (626/10013) NTRK fusion. Significant differences of gene fusion frequency between different sample groups were found via fisher exact test ( p = 0.005), especially ALK fusion ( p = 0.001). Conclusions: The frequency of fusion in MPE was significantly higher than in tumor tissue, especially ALK fusion. However, as a retrospective study, the conclusions and the specific mechanisms are needed to be verified.

10522 Background: Lung cancer is one of the most common types of cancer, ranking the first in the incidence and mortality of malignant tumors in the world and China. Although studies have been reported that genetic susceptibility to lung cancer is associated with certain germline mutations, the relationship between lung cancer risk and inherited genetic factors remains relatively elusive. However, the effect of germline mutation on TMB in lung cancer has not been explored. Herein, DNA genomic profiling was performed through NGS with a 539-gene panel to explore the germline mutations and the relationship with TMB in Chinese patients with lung cancer. Methods: We retrospectively analyzed the germline mutations through a comprehensive 539-gene profiling of 3541 Chinese patients with lung cancer. 539-gene panel contained germline mutations in 90 hereditary tumor-associated genes. We screened out the pathogenic and likely pathogenic germline mutations according to the standards and guidelines for the interpretation of sequence variants of The American College of Medical Genetics and Genomics (ACMG), and picked out there is no records in Clinvar database and no literature report. TMB of tissue or blood ctDNA in 3541 patients were further analyzed in with pathogenic mutations (P group), with likely pathogenic mutations (LP group), and no germline mutations group (Non-P group). The difference in TMB was analyzed via the Wilcoxon sign test. Results: In 3541 patients with lung cancer, 177 (4.999%) patients were identified harboring pathogenic or likely pathogenic germline mutations, in which 78 P group and 99 LP group, the rest 3364 were Non-P group. The highest prevalence of germline mutation was found in BRCA2 (0.565%), ATM (0.339%), MUTYH (0.282%), and BRCA1 (0.254%). In 177 patients with pathogenic or likely pathogenic germline mutations, 67 mutations were recorded as UNK (unknow) in Clinvar database and no literature report. The media TMB of tissue in P group, LP group and Non-P group were 5.149, 5.535 and 5.547 respectively. The media TMB of blood ctDNA in P group, LP group and Non-P group were 4.257, 3.945 and 4.483 respectively. There was no statistical difference in TMB between P and Non-P groups (tissue p = 0.98; ctDNA p = 0.5). Conclusions: In our study, we firstly identified 67 novel germline mutations and studied on the relationship between germline mutations and TMB in lung cancer, which expanded the understanding of germline mutations.

3119 Background: Li-Fraumeni syndrome (LFS, OMIM #151623) is an autosomal dominant cancer predisposition syndrome. Typical LFS tumors comprise adrenocortical carcinomas, sarcoma, breast cancer and central nervous system tumors. LFS is also associated with an increased risk of a multitude of other common types of cancer, such as prostate cancer, lung cancer, gastric cancer, colorectal cancer, ovarian cancer, melanoma, etc. TP53 germline mutations are the most common gene with LFS. Germline mutations of CHEK2 have been identified as another predisposing gene and associated with a range of cancer types. However, the pattern of TP53 and CHEK2 germline mutations in malignant tumors remains unknown. Methods: We identified 8535 malignant solid tumors patients without selecting age or family history in a retrospective cohort. Germline mutations were categorized based on ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity. The patients were divided into three groups, P group (with pathogenic mutations), LP group (with likely-pathogenic mutations) and Non_P group (neither pathogenic nor likely-pathogenic mutation). Statistical significance was defined as P-value less than 0.05. Results: A total of 461 (461/8535) patients carried TP53 or CHEK2 germline mutations were identified, in which 15 patients with pathogenic mutations and 17 patients with likely-pathogenic mutations. One patient with lung cancer in LP group carried TP53 homozygous mutation ( p. Ser215Ile), and the remaining 31 patients all carried heterozygous mutations. Among these 31 carriers, 16 (51.6%) carried nonsense or missense mutations (10 for nonsense and 6 for missense mutations). 3 patients in the P group carried CHEK2 p. Y139* (one liver cancer patient and two lung cancer patients) were identified. The median age of group P, LP and Non_P was 55 (39 for TP53, 61 for CHEK2), 63 (52 for TP53, 66 for CHEK2) and 59, respectively. Somatic mutation analysis found no significant difference in tumor mutation burden (TMB) among three groups. The SNV/INDEL mutation frequency of LRP1B in the P or LP group was significantly lower than the Non_P group. Conclusions: Our data showed that 0.375% (32/8535) malignant solid tumor patients carried TP53 (16/8535) or CHEK2 (16/8535) germline pathogenic or likely-pathogenic mutations. The relationship between germline mutations and cancer susceptibility will be studied in the future.[Table: see text]

2638 Background: Immune checkpoint inhibitors (ICIs), such as programmed death(ligand)1 (PD-(L)1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, have dramatic effects on treatment in patients with various malignancies. High tumor mutation burden (TMB) is predictive of clinical response to ICI in multiple cancer types. Although age-related immune dysfunction might induce difference on the efficacy of ICIs between younger and older patients, the potential effect of age on the efficacy of ICIs remains little known and controversial. Herein, we aimed to analysis the association between age and the efficacy of ICIs based on MSKCC cohort. Methods: We screened out 1661 patients having complete information with advanced cancer, whose tumors underwent next-generation sequencing (NGS) detection and who were treated with at least one dose of ICI in MSKCC cohort. All patients were divided into two groups according to age, the younger group (age ≤50-year old) and the older group (age > 50-year old). We further analyzed the differences in overall survival (OS) and TMB between the two groups. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated via Cox regression model for OS and P-values were calculated via the Wilcoxon sign test for TMB. We analyzed the effect of age on ICI in lung cancer using the same way. Results: In 1661 patients with cancer in our study, 312 (19%) younger and 1349 (81%) older patients were found. The pooled HRs for OS was 1.28 (95% CI: 1.09-1.52) in younger group compared with older group. In 1661 patients with cancer, there was 350 (21%) patients with lung cancer, including 30 (9%) younger and 320 (91%) older patients. The pooled HRs for OS was 1.45 (95% CI: 0.95-2.23) in younger group compared with older group in lung cancer. In addition, TMB in older group was higher than in younger group and significant difference of TMB was found via the Wilcoxon sign test (p = 2.6e-10) between the two groups, especially in lung cancer (p = 1e-4). Conclusions: Our study assessed the impact of age on the efficacy of ICIs using the threshold of 50 years old for the first time and we founded that patients in older group had higher TMB and longer OS than younger group.

e15001 Background: Overall survival (OS) is an important endpoint, with the advantage that there is minimal ambiguity in defining an OS event; the patient is either alive or dead. Some single gene mutations, such as TP53, were identified as important predictors of shorter OS in malignant tumors. However, the relationship between gene co-mutation and OS of malignant tumors is poorly defined. Methods: Genomic and OS data were derived from The Cancer Genome Atlas (TCGA) databases. We defined the double-mutant gene pair as “hit pair” in the specific cancer type if statistically significant OS difference was observed in at least one of three comparison (double-mutant samples vs gene A-only-mutant samples; double-mutant samples vs gene B-only-mutant samples; gene A-only-mutant samples vs gene B-only-mutant samples). Results: PIK3CA-TP53 co-mutation was evaluated as “hit pair” in seven cancer types: GBM (Glioblastoma multiforme), HNSC (Head and neck squamous cell carcinoma), LUSC (Lung squamous cell carcinoma), SARC (Sarcoma), SKCM (Skin cutaneous melanoma), UCEC (Uterine corpus endometrial carcinoma), and UCS (Uterine carcinosarcoma). In SARC and SKCM, the expected hazard ratio was higher in both-mutant group than TP53-only-mutant group, and neither genes were correlated with OS. Especially in SKCM, after we took “neither” group (both genes were wild-type) into comparison, hazard ratio of both-mutant group was significantly higher than neither group. Single-gene mutation didn’t make difference on hazard ratio, which indicated that the both-mutant interaction made the leading contribution. In GBM, LUSC, and UCS, the significant difference of hazard ratio between TP53-only-mutant group and PIK3CA-only-mutant group was neutralized in the both-mutant group, to some extent equivalent to “average effect (OS curve of double-mutant group was between that of only single gene mutant groups)". For PIK3CA-TP53 in HNSC, both-mutant group and TP53-only-mutant group carried with a higher hazard ratio than PIK3CA-only-mutant group. It suggested that the increasing hazard ratio in both-mutant group might be resulted from TP53 mutation. For the circumstance in UCEC, TP53 and PIK3CA were testified to be correlated with higher and lower hazard ratio, respectively and both-mutant group and TP53-only-mutant group both with significantly higher hazard ratio than PIK3CA-only-mutant group, which further verified the greater strength of TP53 than PIK3CA in both-mutant group. Conclusions: In summary, our study identified PIK3CA-TP53 co-mutation as a predictor of OS in seven cancer types: GBM, HNSC, LUSC, SARC, SKCM, UCEC, and UCS, especially in SARC and SKCM.

e15002 Background: Kinase fusions have been proved as driver factors and drug targets for lung cancer. DNA-based next-generation sequencing (NGS) has been widely used for gene fusion detection in patients with lung cancer and intergenic-breakpoint fusions can be detected, in which breakpoints localize to intergenic regions. Theoretically, intergenic-breakpoint fusions are unlikely to be functional, but recent studies have found that intergenic-breakpoint fusions are potentially activated. However, the proportion of intergene-breakpoint fusion occurrence in lung cancer is still unclear. Hereby, next generation sequencing was performed to describe lung intergenic-breakpoint fusions for further research. Methods: Tumor tissue, pleural effusion, or blood samples of 6798 patients with lung cancer from Simceredx were collected for targeted NGS panel sequencing from June 2020 to January 2021. Gene rearrangements of ALK, ROS1, RET, NTRK(1-3) were assessed. Results: We found gene fusions in 4.43% (301/6798) patients with lung cancer totally, of which 59.1% (178/301) ALK fusions, 18.9% (57/301) RET fusions, 15.9% (48/301) ROS1 fusions and 6.64% (20/301) NTRK(1-3) fusions. The intergenic-breakpoint fusions accounted for all fusions of ALK, RET and ROS1 genes were 24.2% (43/178), 22.8% (13 /57) and 18.8% (9/48), respectively. In patients with NTRK intergenic fusions (50.0%, 10/20), NTRK1, NTRK2 and NTRK3 was involved in 2, 1, 7, respectively. Co-occurrence of different fusions was rare. Conclusions: Our data firstly revealed the specific intergenic-breakpoint fusions ( ALK, RET, ROS1, NTRK1-3) in lung cancer. The functional consequences identifying by RNA or protein assay and clinical validation need to be carried out in the future.

e22500 Background: Breast cancer susceptibility genes BRCA1 and 2 are tumor suppressor genes and they play an important role in DNA damage response and repair during homologous recombination. Hereditary breast and ovarian cancer (HBOC) syndrome is an autosomal dominant disease due to BRCA1 and 2 germline mutation. Germline mutations of BRCA1 and 2 genes significantly increase the risk of developing breast cancer, ovarian cancer, prostate cancer and a broad range of cancers. PARP inhibitor (PARPi) monotherapy and combinations have shown promising efficacy against a variety of cancer types with BRCA mutations. Nevertheless, the knowledge of incidence of BRCA1 and 2 germline mutations in solid tumor remains poorly understood. Herein, next generation sequencing of 539-gene profiling was performed to explore the incidence of BRCA1 and 2 germline mutations in Chinese solid tumors. Methods: We retrospectively analyzed the BRCA1 and BRCA2 germline mutations from a comprehensive 539-gene profiling of 8535 Chinese patients with pan-cancer. 539-gene profiling contains the somatic mutations in tumor tissue or blood ctDNA and the germline mutations in blood leukocyte. We screened out the pathogenic and likely pathogenic mutations in BRCA germline mutations, and calculated the mutation frequency and the median age in every cancer type. Results: In 8535 patients with pan-cancer, 110 patients were found pathogenic or likely pathogenic germline mutations in BRCA gene and the mutation frequency was 1.29%, of which 40 BRCA1 mutations and 70 BRCA2 mutations were found in patients, respectively. The total median age was 58.15. Eliminated a few types of cancers that had a smaller number (less than 50), the higher frequency of mutations contained ovarian cancer (14.78%, media age 58), prostatic cancer (6%, media age 58.33), breast cancer (5.2% media age 57.33). The details of the top 8 cancer types with mutation frequency and media age were shown in Table. Conclusions: This was the first report of the incidence of BRCA1 and 2 germline mutations in Chinese solid tumors, which expanded the understanding of BRCA1/2 and provided a direction for clinical trial design of PARPi monotherapy and combinations.[Table: see text]

Disintegrin and metalloproteinase 28 (ADAM28) is a member of the disintegrin and metalloprotease domain (ADAM) family. It is associated with the growth and metastasis of various malignancies in vivo, but its role in gastric cancer remains unclear. The purpose of this study was to investigate the effect of ADAM28 derived from gastric cancer and endothelium on gastric cancer cells and its related mechanisms. In this study, Western blot analysis and q-PCR results showed that ADAM28 was up-regulated in gastric cancer cell lines. The TCGA database showed that patients with high ADAM28 expression had significantly shorter overall survival than those with low ADAM28 expression. By MTT analysis, wound healing assay, and flow cytometry, we found that overexpression/knockdown of ADAM28 expression in gastric cancer cells can regulate cell proliferation, apoptosis and migration in vitro. In addition, overexpression/knockdown of ADAM28 in human umbilical vein endothelial cells (HUVECs) in the upper ventricle can regulate the apoptosis of lower ventricular gastric cancer cells in the co-culture system. Furthermore, ELISA demonstrated that knockdown of ADAM28 from endothelial cells increased the expression of von Willebrand Factor (vWF) in the supernatant. We found that ADAM28 both from gastric cancer cells and HUVECs eliminated vWF-induced apoptosis of gastric cancer cells by cleaving vWF, and the addition of the vWF knockdown plasmid eliminated the increase of integrin β3, p-TP53 and c-Casp3 caused by ADAM28 knockdown. In conclusion, ADAM28 from endothelium and gastric cancer may cleave vWF to eliminate vWF-induced apoptosis of gastric cancer cells and play an pro-metastasis effect.

Background Platelet glycoprotein Ibα (GPIbα) extracellular domain, which is part of the receptor complex GPIb-IX-V, plays an important role in tumor metastasis. However, the mechanism through which GPIbα participates in the metastatic process remains unclear. In addition, potential bleeding complication remains an obstacle for the clinical use of anti-platelet agents in cancer therapy. Methods We established a series of screening models and obtained rat anti-mouse GPIbα monoclonal antibodies (mAb) 1D12 and 2B4 that demonstrated potential value in suppressing cancer metastasis. To validate our findings, we further obtained mouse anti-human GPIbα monoclonal antibody YQ3 through the same approach. Results 1D12 and 2B4 affected the von Willebrand factor (vWF)-GPIbα interaction via binding to GPIbα aa 41-50 and aa 277-290 respectively, which markedly inhibited the interaction among platelets, tumor cells, and endothelial cells in vitro, and reduced the mean number of surface nodules in the experimental and spontaneous metastasis models in vivo. As expected, YQ3 inhibited lung cancer adhesion and demonstrated similar value in metastasis. More importantly, for all three mAbs in our study, none of their Fabs induced thrombocytopenia. Conclusion Our results therefore supported the hypothesis that GPIbα contributes to tumor metastasis and suggested potential value of using anti-GPIbα mAb to suppress cancer metastasis.

Nitric oxide (NO) is a versatile endogenous molecule, involved in various physiological processes and implicated in the progression of many pathological conditions. Therefore, NO donors are valuable tools in NO related basic and applied applications. The traditional spontaneous NO donors are limited in scenarios where flux, localization, and dose of NO could be monitored. This has promoted the development of novel NO donors, whose NO release is not only under control, but also self-calibrated. Herein, we reported a phototriggered and photocalibrated NO donor (NOD565) with an N-nitroso group on a rhodamine dye. NOD565 is nonfluorescent and could release NO efficiently upon irradiation by green light. A bright rhodamine dye is generated as a side-product and its fluorescence can be used to monitor the NO release. The potentials of NOD565 in practical applications are showcased in in vitro studies, e.g., platelet aggregation inhibition and fungi growth suppression.

Polypyrimidine tract-binding protein 3 (PTBP3) is an essential RNA-binding protein with roles in RNA splicing, 3′ end processing and translation. Although increasing evidence implicates PTBP3 in several cancers, its role in gastric cancer metastasis remains poorly explored. In this study, we found that PTBP3 was upregulated in the gastric cancer tissues of patients with lymph node metastasis. Patients with high PTBP3 expression levels had significantly shorter survival than those with low PTBP3 expression. Overexpression/knockdown of PTBP3 expression had no effect on proliferation, whereas it regulated migration and invasion in vitro. In addition, when a mouse xenotransplant model of MKN45 was established, knockdown of PTBP3 in MKN45 cells caused the formation of tumours that were smaller in size than their counterparts, with suppression of tumour lymphangiogenesis and metastasis to regional lymph nodes. Furthermore, we identified caveolin 1 (CAV1) as a downstream target of PTBP3. RNA immunoprecipitation (RIP) assays and dual-luciferase reporter gene assays indicated that PTBP3 interacted with the CU-rich region of the CAV1 gene to downregulate CAV1α expression. Knockdown of CAV1α abrogated the reduction of FAK and Src induced by PTBP3 knockdown. In summary, our findings provide experimental evidence that PTBP3 may function as a metastatic gene in gastric cancer by regulating CAV1 through alternative splicing.

The aerial parts of Salvia miltiorrhiza Bunge, as the non-medicinal parts, are always discarded during harvesting, resulting in a huge waste of resources and environmental pressure. Due to the high flavonoid content and their antioxidant activities characteristics, the aerial parts of S. miltiorrhiza can be developed into natural antioxidants and used in foods. A high-speed counter-current chromatography (HSCCC) method, using a two-phase solvent system composed of tert-butyl methyl ether/n-butanol/acetonitrile/water (3:1:1:20, v/v), was the first to successfully isolate five flavonoids from the aerial parts of S. miltiorrhiza in one attempt, and separately categorized as rutin (1), isoquercitrin (2), kaempferol-3-O-&alpha, l-rhamnopyranosyl-(1&rarr, 6)-&beta, d-glucopyranoside (3), kaempferol-3-O-&beta, d-glucopyranoside (4) and apigenin-7-O-&beta, d-glucopyranoside (5) after identification. The purities of these plant isolates were 97.3%, 99.5%, 92.8%, 98.1% and 98.7%, respectively. All the flavonoids were identified by HR-ESI-MS, 1D and 2D NMR. Compounds 3 and 5 were firstly isolated from the plant of S. miltiorrhiza. Results from antioxidant assays showed that rutin (1) and isoquercitrin (2) had higher antioxidant capacities compared to L-ascorbic acid as the positive control.

Hypericin is an endoplasmic reticulum (ER)-located photosensitizer, which causes oxidative damage to ER during photodynamic therapy (PDT). Hypericin-mediated PDT (HY-PDT) has been confirmed to enhance chemo-sensitivity of oxaliplatin (L-OHP) in colon cancer cells. The present study reveals that autophagy plays a key role in chemosensitization during HY-PDT. We proved pro-death autophagy was required for sensitization and HY-PDT/L-OHP antitumor synergism. High dosage of HY-PDT induced autophagic cell death; while low dose of HY-PDT predominantly triggered protective autophagy and promoted cell proliferation. Low dose of HY-PDT reduced the cytotoxicity of L-OHP in oxaliplatin-resistant colon cancer cells. Different level of autophagy therefore contributed to the opposite effect of HY-PDT on cell fate and chemo-sensitivity. Furthermore, we revealed the role of CHOP as a regulator connecting pro-survival and pro-death autophagy under ER damage. High dose of HY-PDT induced massive ROS generation and severe ER stress, which then led to induction of CHOP. CHOP thereby activated CHOP/TRIB3/Akt/mTOR cascade and triggered autophagic cell death. Additionally, when apoptotic pathway was blocked, cells treated with high dose of HY-PDT preferentially underwent death through autophagic pathway. On the other hand, suppression of autophagy made cells more vulnerable to apoptosis under low dose of HY-PDT. These results provided new evidences for the clinical application of ER-targeting PDT in modifying chemosensitivity of colorectal cancer therapy.