Search

Despite the connection of secretory cells to distinct mucus-containing colon cancer histological subtypes and the interaction of secretory cells with immune cells in the pathogenesis of intestinal inflammatory diseases, whether the secretory cell signatures are associated with tumor microenvironment (TME) heterogeneity and can aid in colon cancer patient classification have not been investigated. Here, by performing the principal component analysis and consensus clustering analysis, we identified four distinct expression patterns based on secretory cell signatures which were significantly associated with different clinical behaviors, TME landscape, pathway activation, genomic mutations, and DNA methylation characteristics. Subsequently, a 'SCS score' model was constructed. The high SCS score indicated a pattern of 'secretory cell subtype 2', which was characterized by stromal infiltration and activation, and predicted poor prognosis and low sensitivity to fluorouracil-based chemotherapy and immunotherapy, but high sensitivity to PI3K catalytic subunit inhibitors. In conclusion, our study comprehensively uncovered the tumor heterogeneity related to secretory cell signature expression patterns. Moreover, the SCS score can supplement routine histopathological assessments to guide personalized therapeutic strategies in colon cancer patients.

Hyperactivation of RAS/MAPK signaling is commonly observed in hepatocellular carcinoma (HCC). Gain-of-function mutations of canonical RAS genes, however, are rarely detected and it remains unclear how the activity of this pathway is turned on during hepatocarcinogenesis. We performed a comprehensive analysis of RAS superfamily genetic alterations across ten subfamilies, 152 members in 377 HCC patients from the Cancer Genome Atlas database. RIT1 (Ras-like without CAAX 1) was the most frequently altered RAS member amplified in 13% of the HCC cohort. Both genomic amplification and CREB-mediated transcriptional activation contributed to the elevated RIT1 expression, and its overexpression correlated with RAS/MAPK activation and poor prognosis. Then, we found that RIT1-induced angiogenesis via the MEK/ERK/EIF4E/HIF1-α/VEGFA axis. MAP3K11 and MAP3K12, in addition to CRAF, could mediate this process by binding to RIT1. Moreover, RIT1 increased the phosphorylation of p38 MAPK and AKT to promote cell survival under reactive oxygen species stress. Based on this mechanistic understanding, we treated RIT1-overexpressing HCC with combined regimen sorafenib plus AKT inhibitor, and achieved enhanced antitumor effects in vivo. Our study reveals RAS "orphan" member RIT1 as the most common genetic alteration of RAS family in HCC and combination of sorafenib with AKT inhibitor might be a promising treatment strategy for RIT1-overexpressing HCC.

Medulloblastoma (MB) is a malignant pediatric brain tumor with a poor prognosis. Post-surgical radiation and cisplatin-based chemotherapy have been a mainstay of treatment, which often leads to substantial neurocognitive impairments and morbidity, highlighting the need for a novel therapeutic target to enhance the sensitivity of MB tumors to cytotoxic therapies. We performed a comprehensive study using a cohort of 71 MB patients' samples and pediatric MB cell lines and found that MB tumors have elevated levels of nucleosome remodeling FACT (FAcilitates Chromatin Transcription) complex and DNA repair enzyme AP-endonuclease1 (APE1). FACT interacts with APE1 and facilitates recruitment and acetylation of APE1 to promote repair of radiation and cisplatin-induced DNA damage. Further, levels of FACT and acetylated APE1 both are correlate strongly with MB patients' survival. Targeting FACT complex with CBL0137 inhibits DNA repair and alters expression of a subset of genes, and significantly improves the potency of cisplatin and radiation in vitro and in MB xenograft. Notably, combination of CBL0137 and cisplatin significantly suppressed MB tumor growth in an intracranial orthotopic xenograft model. We conclude that FACT complex promotes chemo-radiation resistance in MB, and FACT inhibitor CBL0137 can be used as a chemo-radiation sensitizer to augment treatment efficacy and reduce therapy-related toxicity in high-risk pediatric patients.

Ting Jiang,1,* Shuang Liu,1,* Xiaojun Wu,2,* Xiaoqing Liu,3 Weizhan Li,4 Shanfei Yang,1 Peiqiang Cai,5 Shaoyan Xi,6 Zhifan Zeng,1 Yuanhong Gao,1 Gong Chen,2 Weiwei Xiao1 1Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, People’s Republic of China; 2Department of Colorectal Surgery, Sun Yat-Sen University Cancer Center, Guangzhou, People’s Republic of China; 3Department of Radiation Oncology, Guangzhou Concord Cancer Center, Guangzhou, People’s Republic of China; 4Department of Radiation Oncology, Panyu Center Hospital, Guangzhou, People’s Republic of China; 5Department of Radiology, Sun Yat-Sen University Cancer Center, Guangzhou, People’s Republic of China; 6Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Gong Chen; Weiwei Xiao Email chengong@sysucc.org.cn; xiaoww@sysucc.org.cnPurpose: This study aimed to predict the risks of distant metastasis (DM) of locally advanced rectal cancer (LARC) patients with pathological complete response (pCR) after neoadjuvant chemoradiotherapy (NACRT) and total mesorectal excision (TME), and to find the association between adjuvant chemotherapy (ACT) and their survival outcomes.Methods and Materials: A total of 242 patients with LARC achieving pCR after NACRT were enrolled in this retrospective study. We developed a nomogram model using logistic regression analyses for predicting risk of DM. The model performance was evaluated by the concordance index and calibration curve. Survival was determined using Kaplan–Meier survival curve.Results: Age, pre-operative CEA, pre-treatment CEA and distance of tumor to anal verge were identified as significantly associated variables that could be enrolled in the model to predict the risk of DM for pCR patients. The nomogram we created had a bootstrapped-concordance index of 0.731 (95% CI = 0.627 to 0.834) and was well calibrated. The high risk group was more likely to develop DM than low risk group (total score) (95% CI = 1.439 to 6.493, P = 0.0036). The 1-year, 3-year, and 5-year distant metastasis-free survival (DMFS) for the low and high risk groups (total score ≤ 90 vs > 90) was 97.8%, 94.2%, 94.2% and 91.3%, 83.4%, 81.8%, respectively (P = 0.0036). DM occurred within 1 and 2 years after TME surgery was 33.3% and 55.6% for the low risk group, and 47.3% and 84.2% for the high risk group. The value of ACT was assessed among the whole cohort, patients with cT3-4, with cN+ or with either DM risk group, but no significant difference was observed concerning DMFS whether ACT was given or not (all P > 0.05). Active treatment after DM was more beneficial than palliative treatment (P < 0.001).Conclusion: The nomogram model, including age, pre-operative CEA, pre-treatment CEA and distance to anal verge, predicted the probability of DM among LARC patients achieving pCR after NACRT. The effects of ACT were not seen in different subgroups, while closer clinical follow-up may have greater contribution to pCR patients in the first 2 years, especially for patients with relatively higher risk to develop DM. It is suggested that timely active treatment can bring survival benefit for pCR patients developing DM after NACRT.Keywords: locally advanced rectal cancer; LARC, pathological complete response; pCR, adjuvant chemotherapy; ACT, distant metastasis; DM

Genomic alteration can reshape tumor microenvironment to drive tumor malignancy. However, how PTEN deficiency influences microenvironment-mediated cell-cell interactions in glioblastoma (GBM) remains unclear. Here, we show that PTEN deficiency induces a symbiotic glioma-M2 macrophage interaction to support glioma progression. Mechanistically, PTEN -deficient GBM cells secrete high levels of galectin-9 (Gal-9) via the AKT-GSK3β-IRF1 pathway. The secreted Gal-9 drives macrophage M2 polarization by activating its receptor Tim-3 and downstream pathways in macrophages. These macrophages, in turn, secrete VEGFA to stimulate angiogenesis and support glioma growth. Furthermore, enhanced Gal-9/Tim-3 expression predicts poor outcome in glioma patients. In GBM models, blockade of Gal-9/Tim-3 signaling inhibits macrophage M2 polarization and suppresses tumor growth. Moreover, α-lactose attenuates glioma angiogenesis by down-regulating macrophage-derived VEGFA, providing a novel antivascularization strategy. Therefore, our study suggests that blockade of Gal-9/Tim-3 signaling is effective to impair glioma progression by inhibiting macrophage M2 polarization, specifically for PTEN -null GBM.

Background Alterations in histone modifications have been reported to be related to tumorigenicity and tumor progression. However, whether histone modification can aid the classification of patients or influence clinical behavior in patients with colon cancer remains unclear. Therefore, this study aimed to evaluate histone modifier expression patterns using the unsupervised clustering of the transcriptomic expressions of 88 histone acetylation and methylation regulators. Results In this study, by consensus clustering analysis based on the transcriptome data of 88 histone modification regulators, we identified four distinct expression patterns of histone modifiers associated with different prognoses, intrinsic fluorouracil sensitivities, biological pathways, and tumor microenvironment characteristics among 1372 colon cancer samples. In these four clusters, the HMC4 cluster represented a stroma activation phenotype characterized by both the worst prognosis and lowest response rates to fluorouracil treatment. Then, we established a scoring scheme comprising 155 genes designated as “HM_score” by using the Boruta algorithm to distinguish colon cancer patients within the HMC4 cluster. Patients with a high HM_score were considered to have high stromal pathway activation, high stromal fraction, and an unfavorable prognosis. Further analyses indicated that a high HM_score also correlated with reduced therapeutic benefits from fluorouracil chemotherapy. Moreover, through CRISPR library screening, ZEB2 was found to be a critical driver gene that mediates fluorouracil resistance, which is associated with histone modifier expression patterns. Conclusions This study highlights that characterizing histone modifier expression patterns may help better understand the epigenetic mechanisms underlying tumor heterogeneity in patients with colon cancer and provide more personalized therapeutic strategies.

Various scoring systems have been proposed to predict the postoperative prognosis of colorectal liver metastasis (CRLM), including the clinical risk score (CRS), the immunoscore and so on. Recently, histopathological growth patterns (HGPs) have been recognized. However, the correlation between HGPs and the immunoscore, and their prognostic values in patients with CRLM after liver resection remain undetermined. In this study, HGPs were retrospectively evaluated in HE-stained slides from 166 CRLM patients. The immunoscore was calculated according to the densities of immunostained CD3 + and CD8 + cells. A risk score combining HGPs, the immunoscore and the CRS was defined and divided patients into the low-, medium- and high-risk group. Our results showed that the densities of CD3 + and CD8 + cells were higher in the desmoplastic HGP (dHGP) group than in the non-dHGP group, and the proportion of high immunoscores was also higher in the dHGP group (51.9% vs. 33.0%, respectively, P = 0.020). Patients with the dHGP had significantly longer relapse-free survival (RFS) and overall survival (OS) than those with the non-HGP. The low-risk group showed significantly higher 2-year RFS and 5-year OS rates than the other two groups (RFS: 76.2%, 43.7% and 33.1%, respectively; P 0.001; OS: 89.7%, 54.4% and 33.3%, respectively; P 0.001). In conclusion, the dHGP correlates with relatively high immunoscores, predicting a favorable prognosis independent of the immunoscore and CRS. A novel risk score combining HGPs, the immunoscore and the CRS may be used for the stratification of CRLM patients' survival.

ImportanceHigh-grade gliomas (HGGs) constitute the most common and aggressive primary brain tumor, with 5-year survival rates of 30.9% for grade 3 gliomas and 6.6% for grade 4 gliomas. The add-on efficacy of interferon alfa is unclear for the treatment of HGG.ObjectivesTo compare the therapeutic efficacy and toxic effects of the combination of temozolomide and interferon alfa and temozolomide alone in patients with newly diagnosed HGG.Design, Setting, and ParticipantsThis multicenter, randomized, phase 3 clinical trial enrolled 199 patients with newly diagnosed HGG from May 1, 2012, to March 30, 2016, at 15 Chinese medical centers. Follow-up was completed July 31, 2021, and data were analyzed from September 13 to November 24, 2021. Eligible patients were aged 18 to 75 years with newly diagnosed and histologically confirmed HGG and had received no prior chemotherapy, radiotherapy, or immunotherapy for their HGG.InterventionsAll patients received standard radiotherapy concurrent with temozolomide. After a 4-week break, patients in the temozolomide with interferon alfa group received standard temozolomide combined with interferon alfa every 28 days. Patients in the temozolomide group received standard temozolomide.Main Outcomes and MeasuresThe primary end point was 2-year overall survival (OS). Secondary end points were 2-year progression-free survival (PFS) and treatment tolerability.ResultsA total of 199 patients with HGG were enrolled, with a median follow-up time of 66.0 (95% CI, 59.1-72.9) months. Seventy-nine patients (39.7%) were women and 120 (60.3%) were men, with ages ranging from 18 to 75 years and a median age of 46.9 (95% CI, 45.3-48.7) years. The median OS of patients in the temozolomide plus interferon alfa group (26.7 [95% CI, 21.6-31.7] months) was significantly longer than that in the standard group (18.8 [95% CI, 16.9-20.7] months; hazard ratio [HR], 0.64 [95% CI, 0.47-0.88]; P = .005). Temozolomide plus interferon alfa also significantly improved median OS in patients with O6-methylguanine-DNA methyltransferase (MGMT) unmethylation (24.7 [95% CI, 20.5-28.8] months) compared with temozolomide (17.4 [95% CI, 14.1-20.7] months; HR, 0.57 [95% CI, 0.37-0.87]; P = .008). Seizure and influenzalike symptoms were more common in the temozolomide plus interferon alfa group, with 2 of 100 (2.0%) and 5 of 100 (5.0%) patients with grades 1 and 2 toxic effects, respectively (P = .02). Finally, results suggested that methylation level at the IFNAR1/2 promoter was a marker of sensitivity to temozolomide plus interferon alfa.Conclusions and RelevanceCompared with the standard regimen, temozolomide plus interferon alfa treatment could prolong the survival time of patients with HGG, especially the MGMT promoter unmethylation variant, and the toxic effects remained tolerable.Trial RegistrationClinicalTrials.gov Identifier: NCT01765088

The prognostic heterogeneity in patients with BRAF V600E metastatic colorectal cancer (mCRC) remains poorly defined. Real-world data of 93 BRAF V600E mCRC patients from Sun Yat-sen University Cancer Center were evaluated using the prognostic factors affecting overall survival (OS). Treatment of metastases served as an independent prognosticator, where curative locoregional interventions (LRIs) were associated with superior clinical outcomes (adjusted hazard ratio (HR): 0.46, 95% confidence interval (CI): 0.22–0.98, p = 0.044). The LRIs group showed an improved median OS of 49.4 months versus 18.3 months for the palliative treatments (PTs) group. The median OS of patients with colorectal liver metastasis (CRLM) was significantly prolonged after undergoing LRIs (42.4 vs. 23.7 months, HR: 0.11, 95% CI: 0.01–1.22, p = 0.030), and patients in the LRIs plus liver-limited or lung-limited metastasis (LLM) group benefited more than those in the LRIs plus non-LLM group when compared to the PTs group (LLM from LRIs vs. PTs, HR: 0.16, 95% CI: 0.04–0.68, p = 0.006. Non-LLM from LRIs vs. PTs, HR: 0.47, 95% CI: 0.21–1.05, p = 0.074). In conclusion, we confirmed the positive prognostic value of LRIs in BRAF V600E mCRC, particularly in patients with CRLM or LLM.

Purpose We aim to investigate the impacts of extent of resection and adjuvant radiotherapy on survival of high-grade meningiomas (WHO grade II–III) according to modern diagnosis and management. Methods Patients with high-grade meningiomas were identified in the Surveillance Epidemiology and End Results (SEER) database between 2000 and 2015 and used for survival analysis. Propensity score matching (PSM) was conducted to reduce selection bias. Another 92 patients from Sun Yat-sen University Cancer Center (SYSUCC) were used for validation. Results 530 patients were enrolled from SEER. Patients with gross total resection (GTR) had no significantly different overall survival (OS) compared with those with subtotal resection (STR), even after performing PSM between these two groups. Multivariable analysis found that age ≥ 65 years (HR 2.22, P 6 cm (HR 1.59, P = 0.004) and grade III tumor (HR 4.31, P

High-grade glioma is the most common malignant primary brain tumor in the central nervous system. Multiple strategies such as surgery, radiotherapy, and chemotherapy have been used, but the prognosis of patients with high-grade glioma remains poor. No standard treatment exists for recurrent gliomas; however, combination therapies of programmed cell death protein 1 blockades with antiangiogenic agents have demonstrated promising effects in different solid tumors. We have initiated a clinical trial designed to evaluate the safety and efficiency of neoadjuvant therapy using camrelizumab and apatinib in patients with recurrent highgrade gliomas. In this prospective, Phase II, singlearm study, patients with recurrent highgrade gliomas will receive singledose intravenous injection of camrelizumab (200 mg) and daily oral administration of apatinib (250 mg/day for 7 days) 14 days before surgery for recurrent tumor. Sequential therapy will begin 2 weeks after surgery with the biweekly injection of camrelizumab and 4 weeks after surgery with the daily administration of apatinib. Treatment of camrelizumab and apatinib will be continued until disease progression or unacceptable toxicity or death. The trial is planned to enroll 30 patients. Up-to date (March 31, 2022), 12 patients had been enrolled, in which, 9 were GBM. Three patients died, while 4 cases on trial more than 6 months, the longest already 1 year. Although an evaluation is still impossible to be conducted yet, some patients have shown a promising outcome. We will present updated results on the meeting. These preliminary data suggest that this study would be worthwhile. This study was approved by the Ethics Committee of Sun Yatsen University Cancer Center (Guangzhou, China; approval No. SLB202014901). This study was registered with ClinicalTrials.gov under identifier NCT04588987.

Background Differential diagnosis of tumour recurrence (TuR) from treatment effects (TrE), mostly induced by radiotherapy and chemotherapy, is still difficult by using conventional computed tomography (CT) or magnetic resonance (MR) imaging. We have investigated the diagnostic performance of PET/CT with 3 tracers, 13N-NH3, 18F-FDOPA, and 18F-FDG, to identify TuR and TrE in glioma patients following treatment. Methods Forty-three patients with MR-suspected recurrent glioma were included. The maximum and mean standardized uptake values (SUVmax and SUVmean) of the lesion and the lesion-to-normal grey-matter cortex uptake (L/G) ratio were obtained from each tracer PET/CT. TuR or TrE was determined by histopathology or clinical MR follow-up for at least 6 months. Results In this cohort, 34 patients were confirmed to have TuR, and 9 patients met the diagnostic standard of TrE. The SUVmax and SUVmean of 13N-NH3 and 18F-FDOPA PET/CT at TuR lesions were significantly higher compared with normal brain tissue (13N-NH3 0.696 ± 0.558, 0.625 ± 0.507 vs 0.486 ± 0.413; 18F-FDOPA 0.455 ± 0.518, 0.415 ± 0.477 vs 0.194 ± 0.203; both P 18F-FDG (6.918 ± 3.190, 6.016 ± 2.807 vs 6.356 ± 3.104, P = 0.290 and 0.493). L/G ratios of 13N-NH3 and 18F-FDOPA were significantly higher in TuR than in TrE group (13N-NH3, 1.573 ± 0.099 vs 1.025 ± 0.128, P = 0.008; 18F-FDOPA, 2.729 ± 0.131 vs 1.514 ± 0.141, P 13N-NH3; 84.6%, 100% and 0.938, for 18F-FDOPA; and 80.8%, 100%, and 0.952, for the combination, respectively. Conclusion Our results suggest that although multiple tracer PET/CT may improve differential diagnosis efficacy, for glioma TuR from TrE, 18F-FDOPA PET-CT is the most reliable. The combination of 18F-FDOPA and 13N-NH3 does not increase the diagnostic efficiency, while 18F-FDG is not worthy for differential diagnosis of glioma TuR and TrE.

Hyperactivation of RAS/MAPK signaling is commonly observed in hepatocellular carcinoma (HCC). Gain-of-function mutations of canonical RAS genes, however, are rarely detected and it remains unclear how the activity of this pathway is turned on during hepatocarcinogenesis. We performed a comprehensive analysis of RAS superfamily genetic alterations across ten subfamilies, 152 members in 377 HCC patients from the Cancer Genome Atlas database. RIT1 (Ras-like without CAAX 1) was the most frequently altered RAS member amplified in 13% of the HCC cohort. Both genomic amplification and CREB-mediated transcriptional activation contributed to the elevated RIT1 expression, and its overexpression correlated with RAS/MAPK activation and poor prognosis. Then, we found that RIT1-induced angiogenesis via the MEK/ERK/EIF4E/HIF1-α/VEGFA axis. MAP3K11 and MAP3K12, in addition to CRAF, could mediate this process by binding to RIT1. Moreover, RIT1 increased the phosphorylation of p38 MAPK and AKT to promote cell survival under reactive oxygen species stress. Based on this mechanistic understanding, we treated RIT1-overexpressing HCC with combined regimen sorafenib plus AKT inhibitor, and achieved enhanced antitumor effects in vivo. Our study reveals RAS "orphan" member RIT1 as the most common genetic alteration of RAS family in HCC and combination of sorafenib with AKT inhibitor might be a promising treatment strategy for RIT1-overexpressing HCC.

Hepatocellular carcinoma (HCC) is one of the most common human malignancies worldwide with very poor prognosis. Resistance to targeted therapeutic drugs such as sorafenib remains one of the major challenges in clinical treatment. In the present study, PARP1 was found to be highly expressed in human embryonic stem cells, but progressively decreased upon specified hepatic differentiation. Reactivation of PARP1 expression was also detected in HCC residual tumors after sorafenib treatment in xenograft mouse model, indicating the potential important roles of PARP1 in stem cell pluripotency and HCC sorafenib treatment resistance. Overexpression of PARP1 was frequently observed in HCC patients, and closely associated with poor clinical outcome. Treatment of Sorafenib induced activation of DNA damage repair signaling, which is highly active and essential for maintenance of stem cell pluripotency in HCC residual tumors. PARP inhibitor Olaparib extensively suppressed the DNA damage repair signaling, and significantly inhibited the global pluripotent transcriptional network. The repression of key pluripotent transcriptional factors and DNA damage repair signaling by Olaparib was mainly through CHD1L-mediated condensation of the chromatin structure at their promotor regions. The global reshaping of the pluripotent transcriptome by Olaparib might reinforce Sorafenib in eliminating HCC residual tumors and enhance therapeutic efficiency. Supplementary Information The online version contains supplementary material available at 10.1186/s12943-021-01315-9.

Research over the past decade has suggested important roles for pseudogenes in glioma. This study aimed to show that pseudogene PRELI domain-containing 1 pseudogene 6 (PRELID1P6) promotes glioma progression. Aberrant expression of genes was screened using The Cancer Genome Atlas database. We found that mRNA level of PRELID1P6 was highly upregulated in glioma and was associated with a shorter survival time. Functional studies showed that the knockdown of PRELID1P6 decreased cell proliferation, sphere formation, and clone formation ability and blocked the cell cycle transition at G0/G1, while overexpression of PRELID1P6 had the opposite effects. Mechanistically, knockdown of PRELID1P6 changed the cellular localization of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) from nucleus to cytoplasm, which promoted ubiquitin-mediated degradation of hnRNPH1. RNA-sequence and gene set enrichment analysis suggested that knockdown of PRELID1P6 regulates the apoptosis signaling pathway. Western blotting showed that PRELID1P6 increased TRF2 expression by hnRNPH1-mediated alternative splicing effect and activated the Akt/mTOR pathway. Furthermore, Akt inhibitor MK2206 treatment reversed the oncogenic function of PRELID1P6. PRELID1P6 was also found to be negatively regulated by miR-1825. Our result showed that PRELID1P6 promotes glioma progression through the hnHNPH1-Akt/mTOR pathway. These findings shed new light on the important role of PRELID1P6 as a novel oncogene for glioma.

Long noncoding RNAs (lncRNAs), once considered to be nonfunctional relics of evolution, are emerging as essential genes in tumor progression. However, the function and underlying mechanisms of lncRNAs in glioma remain unclear. This study aimed to investigate the role of LINC00998 in glioma progression. Through screening using TCGA database, we found that LINC00998 was downregulated in glioblastoma tissues and that low expression of LINC00998 was associated with poor prognosis. Overexpression of LINC00998 inhibited glioma cell proliferation in vitro and in vivo and blocked the G1/S cell cycle transition, which exerted a tumor-suppressive effect on glioma progression. Mechanistically, RNA pull-down and mass spectrometry results showed an interaction between LINC00998 and CBX3. IP assays demonstrated that LINC00998 could stabilize CBX3 and prevent its ubiquitination degradation. GSEA indicated that LINC00998 could regulate the c-Met/Akt/mTOR signaling pathway, which was further confirmed by a rescue assay using siRNA-mediated knockdown of CBX3 and the Akt inhibitor MK2206. In addition, dual-luciferase assays showed that miR-34c-5p could directly bind to LINC00998 and downregulate its expression. Our results identified LINC00998 as a novel tumor suppressor in glioma, and LINC00998 could be a novel prognostic biomarker, providing a strategy for precision therapy in glioma patients.

Eukaryotic initiation factor 4A-II (eIF4A2) is an ATP-dependent RNA helicase involved in mRNA translation. Abnormal expression of eIF4A2 has been reported as a prognostic factor in different types of cancer. However, little is known regarding the function of eIF4A2 in esophageal squamous cell carcinoma (ESCC). In the present study, 253 samples were collected from patients diagnosed with ESCC, and the expression of eIF4A2 was detected by immunohistochemical staining. The clinicopathological and prognostic significance of eIF4A2 expression in ESCC were then statistically analyzed. The results demonstrated that eIF4A2 was specifically localized to the cytoplasm. Kaplan-Meier analysis also revealed that eIF4A2 expression was associated with the clinical prognosis of patients with ESCC. The median disease-free and overall survival times were 40 and 48 months for patients with low eIF4A2 expression, compared with 16 and 25 months in the high eIF4A2 expression group, respectively. In conclusion, high expression levels of eIF4A2 are associated with a poor prognosis and may be used as a potential prognostic indicator in patients with ESCC.

Purpose To construct and validate a predicting genotype signature for pathologic complete response (pCR) in locally advanced rectal cancer (PGS-LARC) after neoadjuvant chemoradiation. Methods and Materials Whole exome sequencing was performed in 15 LARC tissues. Mutation sites were selected according to the whole exome sequencing data and literature. Target sequencing was performed in a training cohort (n = 202) to build the PGS-LARC model using regression analysis, and internal (n = 76) and external validation cohorts (n = 69) were used for validating the results. Predictive performance of the PGS-LARC model was compared with clinical factors and between subgroups. The PGS-LARC model comprised 15 genes. Results The area under the curve (AUC) of the PGS model in the training, internal, and external validation cohorts was 0.776 (0.697-0.849), 0.760 (0.644-0.867), and 0.812 (0.690-0.915), respectively, and demonstrated higher AUC, accuracy, sensitivity, and specificity than cT stage, cN stage, carcinoembryonic antigen level, and CA19-9 level for pCR prediction. The predictive performance of the model was superior to clinical factors in all subgroups. For patients with clinical complete response (cCR), the positive prediction value was 94.7%. Conclusions The PGS-LARC is a reliable predictive tool for pCR in patients with LARC and might be helpful to enable nonoperative management strategy in those patients who refuse surgery. It has the potential to guide treatment decisions for patients with different probability of tumor regression after neoadjuvant therapy, especially when combining cCR criteria and PGS-LARC.

Twist is a transcription factor involved in the process of epithelial to mesenchymal transition (EMT) of carcinoma cells, and the promotion of invasion of gliomas through the mesenchymal adjusting process. However, its clinical significance in human glioma has not yet to be understood. To delineate the clinical-pathological significance and prognostic value of Twist, the expression of Twist was evaluated by Immunohistochemistry for 187 glioma samples. We found that Twist demonstrated frequent nuclear expression in the glioma samples and its expression levels were associated with tumor grade (P0.001). Furthermore, high Twist expression was correlated with a poor outcome in patients with glioma (P=0.001), particularly with high grade glioma (P=0.026). Interestingly, Twist expression showed positive correlation with microvascular density (MVD) (r=0.145, P=0.048) as well as vasculogenic mimicry (VM) (r=0.273, P0.001) in the tumors. These results suggest that Twist could be a predictor for poor prognosis in glioma patients. Additionally, Twist expression was associated with two major microcirculation patterns: endothelial-dependent vessels and VM in glioma, indicating that Twist could be a potential molecular target for anti-glioma therapy.

Twist is a transcription factor involved in the process of epithelial to mesenchymal transition (EMT) of carcinoma cells, and the promotion of invasion of gliomas through the mesenchymal adjusting process. However, its clinical significance in human glioma has not yet to be understood. To delineate the clinical-pathological significance and prognostic value of Twist, the expression of Twist was evaluated by Immunohistochemistry for 187 glioma samples. We found that Twist demonstrated frequent nuclear expression in the glioma samples and its expression levels were associated with tumor grade (P

The latest WHO guideline of CNS tumor defined a RELA fusion-positive ependymoma type with extremely poor prognosis, and the expression of L1CAM was correlated well with the presence of RELA fusion. However, the L1CAM protein expression in large sample gliomas other than ependymoma, its relationship with the RELA gene and its prognostic significance remained unknown. We examined the expression of L1CAM in 565 glioma cases (WHO grade I-IV). The L1CAM IHC-positive cases were selected to test RELA fusion with FISH break-apart probes. L1CAM was positive in 109 cases (19.29%) of all 565 glioma cases, with 18.27% in low-grade gliomas and 19.84% in high-grade gliomas, respectively. Unlike ependymoma, L1CAM protein expression was not correlated with the C11orf95-RELA fusion gene in other gliomas, but it had correction with the patient age (older than 45-year-old, p=0.006), ATRX mutation (p=0.003) and Ki67 (p=0.007). High expression of L1CAM was an independent prognostic factor in our cohort. Further analysis demonstrated that L1CAM strong positive expression was significantly associated with poor prognosis in gliomas, both in our cohort (p<0.001) and TCGA (p<0.009) dataset. Although uncorrelated with C11orf95-RELA fusion, L1CAM was a significant poor prognostic marker in glioma patients. More aggressive treatment should be taken for these patients and L1CAM might be a promising therapeutic target in glioma.

TPS210 Background: Neoadjuvant chemoradiotherapy (NACRT) could bring tumor downstaging and pathological response (pCR), and also survival benefit for locally advanced rectal cancer (LARC) patients. Several single arm prospective clinical trials have investigated combination effect of immunotherapy (PD-1 or PD-L1 antibody) and NACRT in LARC patients, such as the VOLTAGE clinical trial. A randomized trial is needed to confirm the benefit of immunotherapy in this setting and explore predictive biomarkers. This is a clinical trial with two cohorts according the MMR/MSI status (clinicalTrials.gov, NCT04304209). Methods: In this study, LARC patients with pMMR/MSS/MSI-L tumor will enter cohort B and be randomized into two arms. Main inclusion criteria include: cT3-4N0M0 or cTxN+M0 rectal adenocarcinoma, pMMR/MSS/MSI-L confirmed by immunohistochemistry or gene test, aged 18-75y; ECOG performance 0-1; no previous anti-tumor treatment for rectal adenocarcinoma. Main exclusion criteria include: active autoimmune diseases or a history of autoimmune diseases, and inadequate main organ functions. Patients in the experimental arm will receive four cycles of neoadjuvant PD1 antibody Sintilimab, Capeox chemotherapy and concurrent radiotherapy, followed by curative surgery or watch and wait, then four cycles of adjuvant Capeox chemotherapy. Patients in the control arm will receive four cycles of neoadjuvant Capeox chemotherapy and concurrent radiotherapy, followed by curative surgery or watch and wait, then four cycles of adjuvant Capeox chemotherapy Primary outcome measure is pCR rate. Secondary outcome measures include acute toxicity, tumor regression grade, R0 resection rate, local recurrence, distant metastasis. Sample size for this cohort is 134. Whole exome sequencing, RNA sequencing and immunohistochemistry of the rectal primary tumor are planned for biomarker searching and synergy effect mechanism investigation. The first patient has been enrolled in June, 2020. Clinical trial information: NCT04304209.

113 Background: Preoperative chemoradiotherapy followed by total mesorectal excision (TME) surgery has been widely adopted as the standard treatment for stage II-III rectal cancers. However, the role of adjuvant chemotherapy in pathological T3N0M0 (pT3N0M0) patients remains controversial. A reliable prognostic model is needed to discriminate the high-risk patients from the low-risk patients, and optimize adjuvant chemotherapy treatment decisions by predicting the likelihood of adjuvant chemotherapy benefit for the target population. Methods: We gathered and analyzed 276 patients in Sun Yat-Sen University Cancer Center from March 2005 to December 2011. All patients underwent total mesorectal excision, without preoperative therapy, and were pathologically proven pT3N0M0 rectal cancer. LASSO regression model was used for variable selection and risk factor prediction. Multivariable cox regression was used to develop the predicting model. Optimum cut-off values were determined using X-Tile plot analysis. The 10-fold cross validation was adopted to validate the model. The performance of the nomogram was evaluated with its calibration, discrimination and clinical usefulness. Results: A total of 188 patients (68.1%) had adjuvant chemotherapy and no patients had adjuvant radiotherapy. Age, carbohydrate antigen 19-9 [CA199], monocyte percentage [MONO%], lymph node dissection numbers [LNDs] and nerve invasion were identified as significantly associated variables that could be combined for an accurate prediction risk of CSS for pT3N0M0 patients. The model adjusted for CSS showed good discrimination with a C-index of 0.723 (95% CI = 0.652 to 0.794). The calibration curves showed that the nomogram adjusted for CSS was able to predict 3-, 5-, and 10-year CSS accurately. The corresponding predicted probability was used to stratify high and low-risk patients. Adjuvant chemotherapy improved survival rate in the low-risk patients (HR = 0.338, 95% CI: 0.135 to 0.848, P = 0.021), while it did not exhibit a significant benefit in the high-risk patients. Conclusions: The nomogram effectively predicts CSS in patients with pT3N0M0 rectal cancer, which can be conveniently used in clinical practice. Adjuvant chemotherapy may improve overall survival in the low-risk patients. But the benefit of adjuvant chemotherapy was not seen in the high-risk patients.

Jiawang Wei,1–3,* Rong Huang,3,* Suping Guo,1,2,* Xuhui Zhang,1,2 Shaoyan Xi,1,4 Qiaoxuan Wang,1,2 Hui Chang,1,2 Xiaohao Wang,1,2 Weiwei Xiao,1,2 Zhifan Zeng,1,2 Yuanhong Gao1,2 1State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, People’s Republic of China; 2Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People’s Republic of China; 3Department of Oncology, Ganzhou People’s Hospital, Ganzhou, Jiangxi, People’s Republic of China; 4Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People’s Republic of China *These authors contributed equally to this work Background: The purpose of this study was to investigate the value of the postsurgical pathological T and N (ypTN) category combined with the American Joint Committee on Cancer-tumor regression grade (AJCC-TRG) in evaluating the prognosis of neoadjuvant chemoradiation therapy (NeoCRT) for locally advanced rectal cancer (LARC) to screen for a subgroup of patients with the worst prognosis. Patients and methods: In total, 265 patients with LARC were enrolled in the trial. All patients received NeoCRT. Total mesorectal excision was performed 6–8 weeks after the completion of radiotherapy. The surgical specimens were re-evaluated based on the AJCC-TRG (seventh edition) and the AJCC-tumor-node-metastasis (TNM; seventh edition) systems. We followed up these patients and calculated their overall survival (OS), disease-free survival (DFS), local recurrence-free survival (RFS), and distant metastasis (DM)-free survival (MFS) rates through the Kaplan–Meier analysis. The logrank test was further applied to evaluate the predictive value of the ypTN stage combined with AJCC-TRG for several survival indexes. Results: The median follow-up period was 65.1 months. The 5-year OS, DFS, RFS, and MFS rates were 79.4%, 68.8%, 94.4%, and 76.5%, respectively. There were significant differences in OS, DFS, and MFS rates among different ypT+AJCC-TRG and ypN+AJCC-TRG subgroups. The 5-year OS, DFS, and MFS rates for ypT3–4+TRG 1 and ypT3–4+TRG2–3 subgroups were 73.9% vs 65.3%, 61.2% vs 52.9%, and 65.0% vs 61.5%, respectively. The 5-year OS, DFS, and MFS rates for ypN1–2+TRG 0–1 and ypN1–2+TRG2–3 subgroups were 64.8% vs 54.1%, 44.9% vs 41.7%, and 61.4% vs 46.3%, respectively. Conclusion: The ypTNM category combined with the AJCC-TRG can more accurately evaluate the prognosis of patients with LARC and identify the subgroup of patients with the worst prognosis and high risk of developing DM, thereby demonstrating clinical significance in guiding individualized postoperative adjuvant therapy and follow-up for LARC. Keywords: ypTNM, NeoCRT, rectal cancer, locally advanced rectal cancer, LARC, AJCC

Background Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is associated with poor prognosis, and its treatment strategy is still controversial, especially regarding chemotherapy regimens. Case report We present the case of a 49-year-old Chinese male with primary pulmonary LCNEC treated with neoadjuvant and adjuvant chemotherapy with cisplatin plus pemetrexed. A suspected quasi-circular mass in the left lower pulmonary lobe and an enlarged mediastinal lymph node were found. The patient was diagnosed with adenocarcinoma with neuroendocrine differentiation based on computerized tomography-guided percutaneous lung biopsy. An EGFR gene mutation test showed negative results. Cisplatin and pemetrexed were administered as the neoadjuvant chemotherapy regimen. The primary lesion had reduced markedly, and the enlarged mediastinal lymph node had disappeared after two cycles of neoadjuvant chemotherapy. A left lower lobectomy and mediastinal lymph node dissection were performed. The lesion was confirmed as LCNEC based on postoperative histopathological analysis and immunohistochemical results. The patient underwent four cycles of adjuvant chemotherapy with cisplatin and pemetrexed for a month postoperatively, followed by postoperative adjuvant radiotherapy. The patient was still alive after a follow-up of 24 months, with no evidence of tumor recurrence. Conclusion Cisplatin combined with pemetrexed is effective and safe for patients with pulmonary LCNEC.

Ependymomas are glial brain tumors accounting for approximately 2~3% of all primary tumors of the central nervous system (CNS), and 12% of all pediatric intracranial tumors. To better understand the evolution process of ependymomas, we studied the clinical, pathological and genetic development of a rare girl case with repeatedly recurrent ependymoma. This girl was diagnosed as ependymoma at age of 9 years old, and experienced 7 times tumor relapse and received 9 times surgeries but finally ceased at 19 years old with multiregional recurrences. The pathological characteristics, radiographic images and therapeutic strategies of the patient were all retrieved. Molecular markers confirmed the diagnosis of anaplastic ependymoma based on the updated WHO guideline for CNS tumors. Whole-genome sequencing (WGS) was performed to elucidate the landscape of mutation signatures and to identify potential driver mutations along the tumor progression. The seven tumor specimens showed a highly branched evolutionary pattern. There were six gene mutations found in 5 of the 7 specimens (PCDHA4, PCDHA8, SEC14L6, SETD2, RIOK2, and SLCO2A1) and three in 6 of 7 the samples (RYR1, SNX25, DSC2). Strikingly, there was one gene, ADGRL3, which was found to be consistently mutated in the entire disease progression process. Our findings therefore suggest that ADGRL3 might play roles in the disease progression of ependymoma patient.

Background Mature T-cell and natural killer (NK)-cell lymphomas compose a heterogeneous group of non-Hodgkin lymphomas, and extranodal NK/T-cell lymphoma, nasal type (ENKTL) is an aggressive subtype with sporadic CD30 expression. However, the significance of CD30 expression in ENKTL is controversial. We aimed to classify a large cohort of patients with mature T-cell and NK-cell lymphomas according to the 2016 World Health Organization (WHO) classification guidelines and to study the association between CD30 expression and prognosis of patients with ENKTL. Methods We selected consecutive patients with mature T-cell and NK-cell lymphomas who attended our institution between September 1, 2009 and August 31, 2013. We classified the lymphomas according to the 2016 revision of the WHO classification of lymphoid neoplasms, analyzed the associations between CD30 expression and clinicopathologic features of ENKTL patients, and evaluated the prognostic implications of CD30 expression. Results We identified 622 consecutive patients with mature T-cell and NK-cell lymphomas, including 317 (51.0%) patients with ENKTL. In addition, CD30 expression was detected in 43 (47.3%) of a subset of 91 patients with ENKTL. No clinicopathologic features were associated with CD30 expression, and CD30 positivity showed no prognostic significance in patients with ENKTL. Conclusions ENKTL is the most common type of mature T-cell and NK-cell lymphoma diagnosed at our institution. CD30 is frequently expressed in ENKTL and represents a therapeutic target; however, it may not be a prognostic marker.

LAMC1 encodes an extracellular matrix protein, laminin γ1 chain, which is involved in several biological and pathological processes including tissue development, tumor cell invasion and metastasis. In present study, we demonstrated that both LAMC1 protein and mRNA levels were elevated in HCC tissue samples compared with non-cancerous tissue samples according to western blot analyses, immunohistochemistry (IHC) and microarray. Moreover, high LAMC1 expression was positively correlated with incomplete encapsulation (p=0.014), poor overall (OS, p=0.02) and disease-free survival (DFS, p=0.014). Using cell lines, we demonstrated that the levels of LAMC1 mRNA and protein were significantly higher in HCC cell lines than that in LO2 cell line. After the expression of LAMC1 was depressed by siRNA technique, the cell proliferation, migration and invasion were depressed significantly. Taken together, these data suggest that LAMC1 is enriched in HCC; overexpression of LAMC1 predicts poor prognosis, and enhances tumor cell invasion and migration. LAMC1 might be a new biomarker predictive of HCC prognosis and might also be a useful treatment target.

BACKGROUND Glioma often recurs and the imaging evaluation whether the tumor has returned after glioma treatment is still challenging. PET/CT is one of the most important techniques to assess the post-treatment of glioma. However, differentiating tumor recurrence (TuR) from treatment effects (TrE) remains difficult. In this study, we aim to retrospectively compare the diagnostic performance of three PET tracers 13N-NH3, 18F-DOPA, and 18F-FDG on PET/CT in differentiating between TuR and TrE in post-treatment glioma patients. METHODS Forty-three patients with MRI-suspected recurrent glioma were included. The maximum and mean standardized uptake value (SUVmax and SUVmean) of the lesion and the lesion-to-normal Gray-matter cortex uptake (L/G) ratio were recorded and the reference standard was verified by surgical histopathology or more than 6 months of follow-up with clinical/radiological. The diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. RESULTS 34 patients were confirmed as glioma TuR and 9 patients met the standard of TrE. The median time interval from primary diagnosis surgery to PET/CT was 14.83 months (range, 4.10-62.77 months). The SUVmax of 13N-NH3 and 18F-DOPA PET/CT at the lesions was significantly higher than normal brain tissue (13N-NH3 0.696±0.095 vs 0.486±0.071, 18F-DOPA 0.455±0.079 vs 0.194±0.031, both P< 0.001), while 18F-FDG was not (6.918±0.525 vs 6.356±0.510, P=0.290). TuR showed significantly higher L/G ratios than TrE both in 13N-NH3 and 18F-DOPA PET/CT (13N-NH3, 1.573±0.099 vs 1.025±0.128, P=0.008; 18F-DOPA, 2.729±0.131 vs 1.514±0.141, P< 0.001). The sensitivity, specificity and the area under the curve (AUC) by ROC analysis were 57.7, 100% and 0.803 for 13N-NH3, and 84.6, 100% and 0.938 for 18F-DOPA respectively. CONCLUSIONS PET/CT is a powerful tool to distinguish glioma TuR from TrE, and 18F-DOPA PET/CT has remarkably better differential diagnosis efficacy than 13N-NH3 and 18F-FDG.

Background Vessels with different microcirculation patterns are required for glioblastoma (GBM) growth. However, details of the microcirculation patterns in GBM remain unclear. Here, we examined the microcirculation patterns of GBM and analyzed their roles in patient prognosis together with two well‐known GMB prognosis factors (O6‐methylguanine DNA methyltransferase [MGMT] promoter methylation status and isocitrate dehydrogenase [IDH] mutations). Methods Eighty GBM clinical specimens were collected from patients diagnosed between January 2000 and December 2012. The microcirculation patterns, including endothelium‐dependent vessels (EDVs), extracellular matrix‐dependent vessels (ECMDVs), GBM cell‐derived vessels (GDVs), and mosaic vessels (MVs), were evaluated by immunohistochemistry (IHC) and immunofluorescence (IF) staining in both GBM clinical specimens and xenograft tissues. Vascular density assessments and three‐dimensional reconstruction were performed. MGMT promoter methylation status was determined by methylation‐specific PCR, and IDH1/2 mutations were detected by Sanger sequencing. The relationship between the microcirculation patterns and patient prognosis was analyzed by Kaplan‐Meier method. Results All 4 microcirculation patterns were observed in both GBM clinical specimens and xenograft tissues. EDVs were detected in all tissue samples, while the other three patterns were observed in a small number of tissue samples (ECMDVs in 27.5%, GDVs in 43.8%, and MVs in 52.5% tissue samples). GDV‐positive patients had a median survival of 9.56 months versus 13.60 months for GDV‐negative patients (P = 0.015). In MGMT promoter‐methylated cohort, GDV‐positive patients had a median survival of 6.76 months versus 14.23 months for GDV‐negative patients (P = 0.022). Conclusion GDVs might be a negative predictor for the survival of GBM patients, even in those with MGMT promoter methylation.

Although the positivity of human epidermal growth factor receptor 2 (HER2) is low in colorectal cancer (CRC), anti-HER2 is becoming a new target therapy in metastatic colorectal cancer (mCRC). However, assessment of the HER2 scoring system was still not established in CRC. The purpose of our study was to evaluate HER2 status and its correlation with clinicopathological characteristics and survival according to the HER2 diagnostic criteria for gastroesophageal adenocarcinoma (GEA criteria) and the HERACLES diagnostic criteria (HERACLES criteria) in a large cohort of Chinese CRC patients. The HER2 positivity was 2.9% (43/1490) and 2.6% (39/1490) in CRCs based on the GEA criteria and the HERACLES criteria, and 3.7% (9/243) in mCRC according to both criteria. HER2 status was associated with primary tumor location (P = 0.037), regional lymph node metastasis (P = 0.035), and TNM stage (P = 0.022) in CRCs based on the HERACLES criteria. No such association was found based on the GEA criteria. Furthermore, HER2 positive only presented in patients with RAS gene wild type (P = 0.001). Significant difference was only observed between the HER2-positive and HER2-negative groups in terms of disease-free survival for stage II-III CRCs (P = 0.048) according to the HERACLES criteria, but not based on the GEA criteria. Our findings suggest that the frequency of HER2 overexpression or amplification was low in Chinese CRC patients, and provide a rationale for further evaluation of HER2 in CRC based on the HERACLES criteria and the HER2 diagnostic criteria for gastroesophageal adenocarcinoma.

Background: The latest WHO classification of CNS tumors using the integrated phenotypic and molecular parameters (IDH, ATRX, 1p19q, TERT etc.) have reestablished the CNS tumors classification in addition to traditional histology. The establishment of glioma molecular typing can more accurately predict prognosis, better guide individualized treatment to improve survival. Methods: The expression of IDH1, ATRX, PHH3, P53 and Ki67 was detected by IHC. Molecular status of IDH1/2 and TERT were analyzed using Sanger sequencing. MGMT was explored using methylation-specific PCR. 1p/19q codeletion status was firstly detected by FISH, then further confirmed by multiplex PCR-based next generation sequencing. Results: The mutation frequency of IDH1 was 68.7% (79/115) in WHO II astrocytoma, and 82 cases (82/344, 23.8%) were "triple-negative glioma" in our cohort. Multivariate COX analysis revealed that only IDH, 1p/19q, TERT and MGMT were independent prognostic factors. Noteworthily, we found 7 cases of the new molecular phenotype presented as "IDH wildtype and 1p/19q codeletion", not mentioned in the latest WHO guideline. Conclusion: We detected the newly recommended markers in a large cohort of Chinese glioma patients. Our data demonstrated a relatively lower frequency of IDH mutations and a higher prevalence of triple-negative glioma in Chinese compared with American and European, indicating ethnic and geographical difference in some markers. In addition, the new molecular phenotype "IDH wildtype and 1p/19q codeletion" glioma deserved special focus. These findings suggest that further stratification of infiltrating gliomas is needed for different treatment strategy and precision medicine.

Background Ependymal tumors are pathologically defined intrinsic neoplasms originating in the intracranial compartments or the spinal cord that affect both children and adults. The recently integrated classification of ependymomas based on both histological and molecular characteristics is capable of subgrouping patients with various prognoses. However, the application of histological and molecular markers in Chinese patients with ependymomas has rarely been reported. We aimed to demonstrate the significance of histological characteristics, the v-relavian reticuloendotheliosis viral oncogene homolog A (RELA) fusions and other molecular features in ependymal tumors. Methods We reviewed the histological characteristics of ependymal tumors using conventional pathological slides and investigate the RELA fusions and Cylclin D1 (CCND1) amplification by Fluorescence in situ hybridization (FISH) and trimethylation of histone 3 lysine 27 (H3K27me3) expression by immunohistochemistry (IHC) methods. SPSS software was used to analyze the data. Results We demonstrated that hypercellularity, atypia, microvascular proliferation, necrosis, mitosis, and an elevated Ki-67 index, were tightly associated with an advanced tumor grade. Tumor location, necrosis, mitosis and the Ki-67 index were related to the survival of the ependymomas, but Ki67 was the only independent prognostic factor. Additionally, RELA fusions, mostly presented in pediatric grade III intracranial ependymomas, indicated decreased survival times of patients, and closely related to the patients’ age, tumor grade, cellularity, cellular atypia, necrosis and Ki67 index in the intracranial ependymal tumors, whereas reduction of H3K27me3 predicted the worse prognosis in ependymal tumors. Conclusions Histological and molecular features facilitate tumor grading and prognostic predictions for ependymal tumors in Chinese patients.

e15602 Background: Immunotherapy has shown satisfactory effect for dMMR/MSI-H colorectal cancer patients. Whether Pd-1 antibody would bring benefit for dMMR/MSI-H locally advanced rectal cancer (LARC) patients in neoadjuvant setting is worthy of investigation. This is a clinical trial with two cohorts according the MMR/MSI status(clinicalTrials.gov, NCT04304209). Methods: LARC patients with dMMR or MSI-H tumor will enter Cohort A and receive neoadjuvant Pd1 antibody sintilimab for four cycles and subsequent surgery or watch and wait, followed by adjuvant four cycles of Pd1 antibody sintilimab with or without chemotherapy. Main inclusion criteria include: cT3-4N0M0 or cTxN+M0 rectal adenocarcinoma, dMMR/MSI-H confirmed by immunohistochemistry (IHC) or gene test, aged 18-75y; ECOG performance 0-1; no previous anti-tumor treatment for rectal adenocarcinoma. Primary outcome is pathologic complete response (pCR) rate. We use a Simon two-stage optimum design to test the null hypothesis of a 15% pCR rate, the historical response rate to standard neoadjuvant chemoradiotherapy (NACRT), against the desired alternative of 30% pCR rate. This had a one-sided type I error of 5% and a power of 80%. In the first stage of this design, 19 patients will be accrued. If 3 or fewer pCR was observed, the study was to be terminated and declared negative. If the trial goes on to the second stage, a total of 55 patients will be studied. The study was deemed to have met its primary endpoint if confirmed pCR were observed in 13 or more patients. Considering 10% dropout rate, a total of 61 patients will be enrolled. Whole exome sequencing, bulk RNA sequencing, single cell RNA sequencing and IHC of the rectal primary tumor are planned. The study started in October, 2019. Results: Eight patients have been enrolled and six have response evaluation results. Four patients achieved clinical complete response (cCR) after 4 cycles of neoadjuvant Pd1 antibody sintilimab treatment and three of them enter watch and wait strategy and finished the adjuvant 4 cycles of Pd1 antibody sintilimab treatment. The 4th patient was diagnosed as lynch syndrome, but molecular test was not feasible for the tumors located at the sigmoid and hepatic flexure because of ileus. He received subtotal colectomy and tumors at the sigmoid and hepatic flexure also achieved pCR. The 5th patient has partial response after 4 and 8 cycles of sintilimab treatment, and then received Dixon surgery and pathology showed major reponse (5% cancer cell left only in the mucosal layer, ypTis). The 6th patient has partial response after 4 and 8 cycles of sintilimab treatment, and sintilimab was still continued concerning intact bladder conservation. No grade 3 toxicity was noted yet. Conclusions: Pd1 antibody sintilimab achieved 4CR (pCR+cCR) in 6 dMMR/MSI-H LARC patients with limited toxicities. Pd1 antibody is quite effective and may be an alternative for these patients. Clinical trial information: NCT04304209.