Combined DNA Analysis from Stool and Blood Samples Improves Tumor Tracking and Assessment of Clonal Heterogeneity in Localized Rectal Cancer Patients.

Objectives: In this study, stool samples were evaluated for tumor mutation analysis via a targeted next generation sequencing (NGS) approach in a small patient cohort suffering from localized rectal cancer. Introduction: Colorectal cancer (CRC) causes the second highest cancer-related death rate worldwide. Thus, improvements in disease assessment and monitoring that may facilitate treatment allocation and allow organ-sparing "watch-and-wait" treatment strategies are highly relevant for a significant number of CRC patients. Methods: Stool-based results were compared with mutation profiles derived from liquid biopsies and the gold standard procedure of tumor biopsy from the same patients. A workflow was established that enables the detection of de-novo tumor mutations in stool samples of CRC patients via ultra-sensitive cell-free tumor DNA target enrichment. Results: Notably, only a 19% overall concordance was found in mutational profiles across the compared sample specimens of stool, tumor, and liquid biopsies. Conclusion: Based on these results, the analysis of stool and liquid biopsy samples can provide important additional information on tumor heterogeneity and potentially on the assessment of minimal residual disease and clonal tumor evolution.

A combinatorial MRI sequence-based radiomics model for preoperative prediction of microsatellite instability status in rectal cancer.

This study aimed to develop an optimal radiomics model for preoperatively predicting microsatellite instability (MSI) in patients with rectal cancer (RC) based on multiparametric magnetic resonance imaging. The retrospective study included 308 RC patients who did not receive preoperative antitumor therapy, among whom 51 had MSI. Radiomics features were extracted and dimensionally reduced from T2-weighted imaging (T2WI), T1-weighted imaging (T1WI), diffusion-weighted imaging (DWI), and T1-weighted contrast enhanced (T1CE) images for each patient, and the features of each sequence were combined. Multifactor logistic regression was used to screen the optimal feature set for each combination. Different machine learning methods were applied to construct predictive MSI status models. Relative standard deviation values were determined to evaluate model performance and select the optimal model. Receiver operating characteristic (ROC) curve, calibration curve, and decision curve analyses were performed to evaluate model performance. The model constructed using the k-nearest neighbor (KNN) method combined with T2WI and T1CE images performed best. The area under the curve values for prediction of MSI with this model were 0.849 (0.804-0.887), with a sensitivity of 0.784 and specificity of 0.805. The Delong test showed no significant difference in diagnostic efficacy between the KNN-derived model and the traditional logistic regression model constructed using T1WI + DWI + T1CE and T2WI + T1WI + DWI + T1CE data (P > 0.05) and the diagnostic efficiency of the KNN-derived model was slightly better than that of the traditional model. From ROC curve analysis, the KNN-derived model significantly distinguished patients at low- and high-risk of MSI with the optimal threshold of 0.2, supporting the clinical applicability of the model. The model constructed using the KNN method can be applied to noninvasively predict MSI status in RC patients before surgery based on radiomics features from T2WI and T1CE images. Thus, this method may provide a convenient and practical tool for formulating treatment strategies and optimizing individual clinical decision-making for patients with RC.

Assessing circulating tumour DNA (ctDNA) as a prognostic biomarker in locally advanced rectal cancer: a systematic review and meta-analysis.

INTRODUCTION: Circulating tumour DNA (ctDNA) has emerged as a promising biomarker in various cancer types, including locally advanced rectal cancer (LARC), offering potential insights into disease progression, treatment response and recurrence. This review aims to comprehensively evaluate the utility of ctDNA as a prognostic biomarker in LARC. METHODS: PubMed, EMBASE and Web of Science were searched as part of our review. Studies investigating the utility of ctDNA in locally advanced rectal cancer (LARC) were assessed for eligibility. Quality assessment of included studies was performed using the Newcastle Ottawa Scale (NOS) risk of bias tool. Outcomes extracted included basic participant characteristics, ctDNA details and survival data. A meta-analysis was performed on eligible studies to determine pooled recurrence-free survival (RFS). RESULTS: Twenty-two studies involving 1676 participants were included in our analysis. Methodological quality categorised by the Newcastle Ottawa Scale was generally satisfactory across included studies. ctDNA detected at various time intervals was generally associated with poor outcomes across included studies. Meta-analysis demonstrated a pooled hazard ratio of 8.87 (95% CI 4.91-16.03) and 15.15 (95% CI 8.21-27.95), indicating an increased risk of recurrence with ctDNA positivity in the post-neoadjuvant and post-operative periods respectively. CONCLUSION: Our systematic review provides evidence supporting the prognostic utility of ctDNA in patients with LARC, particularly in identifying patients at higher risk of disease recurrence in the post-neoadjuvant and post-operative periods.

Spatial transcriptomic analysis reveals local effects of intratumoral fusobacterial infection on DNA damage and immune signaling in rectal cancer.

Mucinous colorectal cancer (CRC) is a common histological subtype of colorectal adenocarcinoma, associated with a poor response to chemoradiotherapy. The commensal facultative anaerobes fusobacteria, have been associated with poor prognosis specifically in mesenchymal CRC. Interestingly, fusobacterial infection is especially prevalent in mucinous CRC. The objective of this study was therefore to increase our understanding of beneficial and detrimental effects of fusobacterial infection, by contrasting host cell signaling and immune responses in areas of high vs. low infection, using mucinous rectal cancer as a clinically relevant example. We employed spatial transcriptomic profiling of 106 regions of interest from 8 mucinous rectal cancer samples to study gene expression in the epithelial and immune segments across regions of high versus low fusobacterial infection. Fusobacteria high regions were associated with increased oxidative stress, DNA damage, and P53 signaling. Meanwhile regions of low fusobacterial prevalence were characterized by elevated JAK-STAT, Il-17, Il-1, chemokine and TNF signaling. Immune masks within fusobacterial high regions were characterized by elevated proportions of cytotoxic (CD8+) T cells (p = 0.037), natural killer (NK) cells (p < 0.001), B-cells (p < 0.001), and gamma delta T cells (p = 0.003). Meanwhile, fusobacteria low regions were associated with significantly greater M2 macrophage (p < 0.001), fibroblast (p < 0.001), pericyte (p = 0.002), and endothelial (p < 0.001) counts.

Predictive value of FCGBP expression for treatment response and survival in rectal cancer patients undergoing chemoradiotherapy.

Despite neoadjuvant chemoradiotherapy (CRT) being the established standard for treating advanced rectal cancer, clinical outcomes remain suboptimal, necessitating the identification of predictive biomarkers for improved treatment decisions. Previous studies have hinted at the oncogenic properties of the Fc fragment of IgG binding protein (FCGBP) in various cancers; however, its clinical significance in rectal cancer remains unclear. In this study, we first conducted an analysis of a public transcriptome comprising 46 rectal cancer patients. Focusing on cell adhesion during data mining, we identified FCGBP as the most upregulated gene associated with CRT resistance. Subsequently, we assessed FCGBP immunointensity using immunohistochemical staining on 343 rectal cancer tissue blocks. Elevated FCGBP immunointensity correlated with lymph node involvement before treatment (p = 0.001), tumor invasion, and lymph node involvement after treatment (both p < 0.001), vascular invasion (p = 0.001), perineural invasion (p = 0.041), and reduced tumor regression (p < 0.001). Univariate analysis revealed a significant association between high FCGBP immunoexpression and inferior disease-specific survival, local recurrence-free survival, and metastasis-free survival (all p ≤ 0.0002). Furthermore, high FCGBP immunoexpression independently emerged as an unfavorable prognostic factor for all three survival outcomes in the multivariate analysis (all p ≤ 0.025). Enriched pathway analysis substantiated the role of FCGBP in conferring resistance to radiation. In summary, our findings suggest that elevated FCGBP immunoexpression in rectal cancer significantly correlates with a poor response to CRT and diminished patient survival. FCGBP holds promise as a valuable prognostic biomarker for rectal cancer patients undergoing CRT.

New treatment alternatives for primary and metastatic colorectal cancer by an integrated transcriptome and network analyses.

Metastatic colorectal cancer (CRC) is still in need of effective treatments. This study applies a holistic approach to propose new targets for treatment of primary and liver metastatic CRC and investigates their therapeutic potential in-vitro. An integrative analysis of primary and metastatic CRC samples was implemented for alternative target and treatment proposals. Integrated microarray samples were grouped based on a co-expression network analysis. Significant gene modules correlated with primary CRC and metastatic phenotypes were identified. Network clustering and pathway enrichments were applied to gene modules to prioritize potential targets, which were shortlisted by independent validation. Finally, drug-target interaction search led to three agents for primary and liver metastatic CRC phenotypes. Hesperadin and BAY-1217389 suppress colony formation over a 14-day period, with Hesperadin showing additional efficacy in reducing cell viability within 48 h. As both candidates target the G2/M phase proteins NEK2 or TTK, we confirmed their anti-proliferative properties by Ki-67 staining. Hesperadinin particular arrested the cell cycle at the G2/M phase. IL-29A treatment reduced migration and invasion capacities of TGF-ß induced metastatic cell lines. In addition, this anti-metastatic treatment attenuated TGF-ß dependent mesenchymal transition. Network analysis suggests IL-29A induces the JAK/STAT pathway in a preventive manner.

Novel MIR143HG::PLAG1 gene fusion identified in a rectal myxoid leiomyosarcoma.

Myxoid leiomyosarcoma (MLS) is a rare but well-documented tumor that often portends a poor prognosis compared to the conventional leiomyosarcoma. This rare sarcoma has been reported in the uterus, external female genitalia, soft tissue, and other locations. However, a definite rectal MLS has not been reported. Recently five cases of MLS were reported to harbor PLAG1 fusions (TRPS1::PLAG1, RAD51B::PLAG1, and TRIM13::PLAG1). In this report, we present a case of rectal MLS with a novel MIR143HG::PLAG1 fusion detected by RNA next-generation sequencing.

PDCD4-induced oxidative stress through FGR/NF-κB axis in rectal cancer radiotherapy-induced AKI.

This study aimed to investigate the molecular mechanism of the effect of PDCD4 on radiotherapy-induced acute kidney injury (AKI) in rectal cancer through the regulation of FGR/NF-κB signaling. Differentially expressed genes were identified using Gene Expression Omnibus (GEO) datasets (GSE90627 for rectal cancer and GSE145085 for AKI) and R software. The human renal tubular epithelial cell line, HK-2, was used to establish an in vitro model of radiotherapy-induced AKI. RT-qPCR and western blotting were used to detect gene and protein expression levels, respectively. Cell proliferation and apoptosis were assessed using the CCK-8 assay and flow cytometry, respectively. The malondialdehyde and superoxide dismutase levels in the cell culture supernatants were determined. Additionally, an in vivo AKI model was established using BALB/c mice, and kidney tissue morphology, expression of the renal injury molecule KIM-1, apoptosis of renal tubular cells, and TAS and TOS in serum were evaluated. Bioinformatics analysis revealed the upregulated expression of PDCD4 in AKI. In vitro experiments demonstrated that PDCD4 induced apoptosis in renal tubular cells by promoting FGR expression, which activated the NF-κB signaling pathway and triggered an oxidative stress response. In vivo animal experiments confirmed that PDCD4 promoted oxidative stress response and radiotherapy-induced AKI through the activation of the FGR/NF-κB signaling pathway. Silencing PDCD4 attenuated radiotherapy-induced AKI. Our findings suggest that PDCD4 may induce radiotherapy-induced AKI in rectal cancer by promoting FGR expression, activating the NF-κB signaling pathway, and triggering an oxidative stress response.

LncRNAs: Emerging biomarkers and therapeutic targets in rectal cancer.

According to findings, long non-coding RNAs (lncRNAs) have an important function in the onset and growth of various cancers, including rectal cancer (RC). RC offers unique issues in terms of diagnosis, treatment, and results, needing a full understanding of the cellular mechanisms that cause it to develop. This thorough study digs into the various functions that lncRNAs perform in RC, giving views into their multiple roles as well as possible therapeutic consequences. The function of lncRNAs in RC cell proliferation, apoptosis, migratory and infiltrating capacities, epithelial-mesenchymal shift, and therapy tolerance are discussed. Various lncRNA regulatory roles are investigated in depth, yielding information on their effect on essential cell functions such as angiogenesis, death, immunity, and growth. Systemic lncRNAs are currently acknowledged as potential indications for the initial stages of identification of cancer, with the ability to diagnose as well as forecast. Besides adding to their diagnostic utility, lncRNAs offer therapeutic opportunities as actors, contributing to the expanding landscape of cancer research. Moreover, the investigation looks into the assessment and predictive utility of lncRNAs as RC markers. The article also offers insight into lncRNAs as chemoresistance and drug resistance facilitators in the setting of RC.

Association between microsatellite status and characteristics and outcomes of early-onset compared to late-onset rectal cancer.

BACKGROUND: Microsatellite instability (MSI) is an important prognosticator for colorectal cancer (CRC). The present study aimed to assess the impact of MSI status on the characteristics and outcomes of early-onset compared to late-onset rectal cancer. METHODS: This retrospective cohort study used data from the US National Cancer Database (2004-2019) to assess the baseline characteristics, treatment patterns, short-term outcomes, and overall survival (OS) of early-onset rectal adenocarcinoma affecting patients < 50 years compared to late-onset rectal adenocarcinoma according to the MSI status. RESULTS: The present study included 48,407 patients (59.9% male) with rectal cancer, 17.3% of patients were < 50 years and 6.3% had MSI-H tumors. In the early-onset group, patients with MSI-H tumors had a lower mean age (41.5 vs 43 years, p < 0.001) and presented less often with stage IV disease (22.1% vs 17.7%, p = 0.03) and liver metastasis (9.1% vs 13.5%, p = 0.011) than patients with MSS tumors. In the late-onset group, patients with MSI-H and MSS tumors had similar demographics, disease stage, and metastatic pattern, yet MSI-H patients more often received neoadjuvant radiation therapy (58.9% vs 55.1%, p = 0.009) and neoadjuvant systemic therapy (40% vs 36.2%, p = 0.005). In both age groups, MSI-H tumors were associated with more pathologic T3-4 stage and were more likely mucinous and poorly differentiated carcinomas than MSS tumors. The median OS of MSI-H tumors was similar to MSS tumors (108.09 vs 102.31 months, p = 0.1), whether in the early-onset (139.5 vs 134.2 months, p = 0.821) or late-onset groups (106.1 vs 104.3 months, p = 0.236). CONCLUSIONS: In both age groups, MSI-H rectal cancers were more often mucinous and poorly differentiated carcinomas and had pT3-4 stage more often than MSS cancers. MSI-H rectal cancers tend to present less often with distant metastases and nodal involvement than MSS cancers only in early-onset, but not in late-onset rectal cancers. The association between MSI status and survival was not notable in this study, whether in the early-onset or late-onset groups.

Negative prognostic impact of Co-mutations in TGFß and TP53 pathways in surgically resected rectal tumors following neoadjuvant chemoradiotherapy.

BACKGROUND: Preoperative neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME) is a common approach for treating patients with locally advanced rectal cancer. Nevertheless, the mutational profile and its prognostic impact in surgically resected tumor specimens after nCRT remains to be clarified. METHODS: The comprehensive analysis of mutational landscape was retrospectively conducted by target regions sequencing approach that covered 150 tumor-related genes. Univariate and multivariate logistic regression and Cox regression was used to examine the association of mutation status in genes and pathways with pathological response and prognosis. Data from Memorial Sloan Kettering Cancer Center (MSK) cohort was used for comparison with our results. RESULTS: The top five commonly mutated genes in resected rectal tumor tissue samples following nCRT were TP53 (42%), APC (31%), KRAS (27%), PIK3CA (14%) and FBXW7 (11%). Mutations in the WNT pathway, which was mainly represented by APC mutation, were found to be significantly associated with tumor regression grade (TRG) 3. In our cohort, co-mutations in the receptor tyrosine kinase (RTK)/RAS and WNT pathways were found to be independently associated with reduced risk of recurrent and significantly associated with longer disease-free survival (DFS). In both our cohort and the MSK cohort, co-mutations in the TGF-ß and TP53 pathways were significantly associated with worse DFS. CONCLUSIONS: Resected rectal tumor samples from patients without complete pathological response can be appropriately used to detect mutations. Co-mutations in the TGF-ß and TP53 pathways may provide more prognostic information beyond commonly used clinical factors.

ST6GAL1 is associated with poor response to chemoradiation in rectal cancer.

INTRODUCTION: Colorectal cancer is the third most common cause of cancer death. Rectal cancer makes up a third of all colorectal cases. Treatment for locally advanced rectal cancer includes chemoradiation followed by surgery. We have previously identified ST6GAL1 as a cause of resistance to chemoradiation in vitro and hypothesized that it would be correlated with poor response in human derived models and human tissues. METHODS: Five organoid models were created from primary human rectal cancers and ST6GAL1 was knocked down via lentivirus transduction in one model. ST6GAL1 and Cleaved Caspase-3 (CC3) were assessed after chemoradiation via immunostaining. A tissue microarray (TMA) was created from twenty-six patients who underwent chemoradiation and had pre- and post-treatment specimens of rectal adenocarcinoma available at our institution. Immunohistochemistry was performed for ST6GAL1 and percent positive cancer cell staining was assessed and correlation with pathological grade of response was measured. RESULTS: Organoid models were treated with chemoradiation and both ST6GAL1 mRNA and protein significantly increased after treatment. The organoid model targeted with ST6GAL1 knockdown was found to have increased CC3 after treatment. In the tissue microarray, 42 percent of patient samples had an increase in percent tumor cell staining for ST6GAL1 after treatment. Post-treatment percent staining was associated with a worse grade of treatment response (p = 0.01) and increased staining post-treatment compared to pre-treatment was also associated with a worse response (p = 0.01). CONCLUSION: ST6GAL1 is associated with resistance to treatment in human rectal cancer and knockdown in an organoid model abrogated resistance to apoptosis caused by chemoradiation.

Identification of unique rectal cancer-specific subtypes.

BACKGROUND: Existing colorectal cancer subtyping methods were generated without much consideration of potential differences in expression profiles between colon and rectal tissues. Moreover, locally advanced rectal cancers at resection often have received neoadjuvant chemoradiotherapy which likely has a significant impact on gene expression. METHODS: We collected mRNA expression profiles for rectal and colon cancer samples (n = 2121). We observed that (i) Consensus Molecular Subtyping (CMS) had a different prognosis in treatment-naïve rectal vs. colon cancers, and (ii) that neoadjuvant chemoradiotherapy exposure produced a strong shift in CMS subtypes in rectal cancers. We therefore clustered 182 untreated rectal cancers to find rectal cancer-specific subtypes (RSSs). RESULTS: We identified three robust subtypes. We observed that RSS1 had better, and RSS2 had worse disease-free survival. RSS1 showed high expression of MYC target genes and low activity of angiogenesis genes. RSS2 exhibited low regulatory T cell abundance, strong EMT and angiogenesis signalling, and high activation of TGF-ß, NF-κB, and TNF-α signalling. RSS3 was characterised by the deactivation of EGFR, MAPK and WNT pathways. CONCLUSIONS: We conclude that RSS subtyping allows for more accurate prognosis predictions in rectal cancers than CMS subtyping and provides new insight into targetable disease pathways within these subtypes.

Long-Term Outcomes of dMMR/MSI-H Rectal Cancer Treated With Anti-PD-1-Based Immunotherapy as Curative-Intent Treatment.

BACKGROUND: Neoadjuvant anti-PD-1 therapy has shown encouraging efficacy in patients with deficient DNA mismatch repair (dMMR)/microsatellite instability-high (MSI-H) locally advanced rectal cancer (LARC), which suggests its potential as a curative-intent therapy and a promising treatment option for organ preservation. We aimed to investigate the long-term outcomes of patients with dMMR/MSI-H LARC who experienced clinical complete response (cCR) after anti-PD-1 therapy. METHODS: We retrospectively analyzed patients with dMMR/MSI-H LARC who achieved cCR and received nonoperative management following neoadjuvant anti-PD-1-based treatment from 4 Chinese medical centers. Patients were followed up for at least 1 year after they achieved cCR, their clinical data were collected, and survival outcomes were analyzed using the Kaplan-Meier method. RESULTS: A total of 24 patients who achieved cCR and received nonoperative management from March 2018 to May 2022 were included, with a median age of 51.0 years (range, 19.0-77.0 years). The median treatment course to reach cCR was 6.0 (range, 1.0-12.0). Fifteen patients (62.5%) continued their treatments after experiencing cCR, and the median treatment course was 17.0 (range, 3.0-36.0). No local regrowth or distant metastasis was observed in a median follow-up time of 29.1 months (range, 12.6-48.5 months) after cCR. The 3-year disease-free and overall survivals were both 100%. CONCLUSIONS: Patients with dMMR/MSI-H locally advanced or low-lying rectal cancer who achieved cCR following anti-PD-1-based therapy had promising long-term outcomes. A prospective clinical trial with a larger sample size is required to further validate these findings.

Clinical and genetic factors associated with tumor response to neoadjuvant (chemo)radiotherapy, survival and recurrence risk in rectal cancer.

Rectal cancer poses challenges in preoperative treatment response, with up to 30% achieving a complete response (CR). Personalized treatment relies on accurate identification of responders at diagnosis. This study aimed to unravel CR determinants, overall survival (OS), and time to recurrence (TTR) using clinical and targeted sequencing data. Analyzing 402 patients undergoing preoperative treatment, tumor stage, size, and treatment emerged as robust response predictors. CR rates were higher in smaller, early-stage, and intensively treated tumors. Targeted sequencing analyzed 216 cases, while 120 patients provided hotspot mutation data. KRAS mutation dramatically reduced CR odds by over 50% (odds ratio [OR] = 0.3 in the targeted sequencing and OR = 0.4 hotspot cohorts, respectively). In contrast, SMAD4 and SYNE1 mutations were associated with higher CR rates (OR = 6.0 and 6.8, respectively). Favorable OS was linked to younger age, CR, and low baseline carcinoembryonic antigen levels. Notably, CR and an APC mutation increased TTR, while a BRAF mutation negatively affected TTR. Beyond tumor burden, SMAD4 and SYNE1 mutations significantly influenced CR. KRAS mutations independently correlated with radiotherapy resistance, and BRAF mutations heightened recurrence risk. Intriguingly, non-responding tumors with initially small sizes carried a higher risk of recurrence. The findings, even if limited in addition to the imperfect clinical factors, offer insights into rectal cancer treatment response, guiding personalized therapeutic strategies. By uncovering factors impacting CR, OS, and TTR, this study underscores the importance of tailored approaches for rectal cancer patients. These findings, based on extensive analysis and mutation data, pave the way for personalized interventions, optimizing outcomes in the challenges of rectal cancer preoperative treatment.

Total Neoadjuvant Therapy With PD-1 Blockade for High-Risk Proficient Mismatch Repair Rectal Cancer.

Importance: Total neoadjuvant therapy (TNT) is the standard treatment for locally advanced rectal cancer, especially for patients with high-risk factors. However, the efficacy of TNT combined with immunotherapy for patients with proficient mismatch repair (pMMR) rectal cancer is unknown. Objectives: To evaluate the safety and efficacy of TNT with induction chemoimmunotherapy followed by long-course chemoradiation in patients with high-risk, pMMR rectal cancer and to identify potential molecular biomarkers associated with treatment efficacy. Design, Setting, and Participants: This cohort study was a single-arm phase 2 trial conducted at Gastrointestinal Cancer Center, Peking University Cancer Hospital & Institute, from June 2020 to October 2021. Biopsies and plasma were collected before treatment for whole-exome sequencing and cell-free DNA sequencing, respectively. Data were analyzed from May 2022 to September 2022. Interventions: Participants received 3 cycles of induction oxaliplatin and capecitabine combined with camrelizumab and radiotherapy (50.6 Gy in 22 fractions) with concurrent capecitabine. Patients without disease progression received 2 cycles of consolidation oxaliplatin/capecitabine. Main Outcomes and Measures: The primary end point was pathologic complete response rate. Results: Of 25 patients enrolled (19 men [76%]; 6 women [24%]; median [IQR] age, 58 [48-64] years), 22 patients (88%) completed the TNT schedule. The pathologic complete response rate was 33.3% (7/21). Twelve patients (48%) achieved clinical complete response, and 4 patients (16%) chose to watch and wait. R0 resection was achieved in 21 of 21 patients, and the major pathologic response rate was 38.1% (8/21). The most common adverse event was nausea (80%, 20/25); grade 3 toxic effects occurred in 9 of 25 patients (36%). Patients with tumor shrinkage of 50% or greater after induction oxaliplatin/capecitabine and camrelizumab or clinical complete response had higher percentages of LRP1B mutation. Mutation of LRP1B was associated with high tumor mutation burden and tumor neoantigen burden. Patients with high tumor mutation burden all benefited from therapy. Conclusions and Relevance: This study found that TNT with induction chemoimmunotherapy followed by long-course chemoradiation was safe and effective for patients with high-risk rectal cancer with pMMR status. Longer follow-up and larger clinical studies are needed to validate this innovative regimen. There is also an urgent need to further validate the predictive value of LRP1B and discover other novel biomarkers with potential predictive value for rectal cancer.

Bioinformatics analysis of markers based on m6A related to prognosis combined with immune invasion of rectal adenocarcinoma.

BACKGROUND: Colorectal cancer (CRC) is a common form of cancer, with rectal cancer accounting for approximately one-third of all cases. Among rectal cancers, 95% are classified as rectal adenocarcinoma (READ). Emerging evidence suggests that long noncoding RNAs (lncRNAs) play a significant role in the development and progression of various cancers. In our study, we aimed to identify differentially expressed lncRNAs potentially associated with m6A and establish a risk assessment model to predict clinical outcomes for READ patients. METHODS: The READ dataset from the TCGA database was utilized in this study to synergistically and logically integrate m6A and lncRNA, while employing bioinformatics technology for the identification of suitable biomarkers. A risk prediction model comprising m6A-associated lncRNAs was constructed to investigate the prognostic, diagnostic, and biological functional relevance of these m6A-related lncRNAs. RESULTS: Our research builds a composed of three related to m6A lncRNA rectal gland cancer prognosis model, and the model has been proved in the multi-dimensional can serve as the potential of the prognosis of rectal gland cancer biomarkers. Our study constructed a prognostic model of rectal adenocarcinoma consisting of three related m6A lncRNAs: linc00702, ac106900.1 and al583785.1. CONCLUSION: The model has been validated as a potential prognostic biomarker for rectal cancer in multiple dimensions, aiming to provide clinicians with an indicator to assess the duration of straight adenocarcinoma. This enables early detection of rectal cancer and offers a promising target for immunotherapy.

Tumor location matters, next generation sequencing mutation profiling of left-sided, rectal, and right-sided colorectal tumors in 552 patients.

Despite the introduction of new molecular classifications, advanced colorectal cancer (CRC) is treated with chemotherapy supplemented with anti-EGFR and anti-VEGF targeted therapy. In this study, 552 CRC cases with different primary tumor locations (250 left side, 190 rectum, and 112 right side) were retrospectively analyzed by next generation sequencing for mutations in 50 genes. The most frequently mutated genes were TP53 in left-sided tumors compared to right-sided tumors and BRAF in right-sided tumors compared to left-sided tumors. Mutations in KRAS, NRAS, and BRAF were not detected in 45% of patients with left-sided tumors and in 28.6% of patients with right-sided tumors. Liver metastases were more common in patients with left-sided tumors. Tumors on the right side were larger at diagnosis and had a higher grade (G3) than tumors on the left. Rectal tumors exhibit distinctive biological characteristics when compared to left-sided tumors, including a higher absence rate of KRAS, NRAS, and BRAF mutations (47.4% in rectal versus 42.8% in left-sided tumors). These rectal tumors are also unique in their primary metastasis site, which is predominantly the lungs, and they have varying mutation rates, particularly in genes such as BRAF, FBXW7, and TP53, that distinguish them from tumors found in other locations. Primary tumor location has implications for the potential treatment of CRC with anti-EGFR therapy.

Pre-existing subclones determine radioresistance in rectal cancer organoids.

More than half of all patients with cancer receive radiation therapy, but resistance is commonly observed. Currently, it is unknown whether resistance to radiation therapy is acquired or inherently present. Here, we employed organoids derived from rectal cancer and single-cell whole-genome sequencing to investigate the long-term evolution of subclones in response to radiation. Comparing single-cell whole-genome karyotypes between in-vitro-unirradiated and -irradiated organoids revealed three patterns of subclonal evolution: (1) subclonal persistence, (2) subclonal extinction, and (3) subclonal expansion. Organoids in which subclonal shifts occurred (i.e., expansion or extinction) became more resistant to radiation. Although radioresistant subclones did not share recurrent copy-number alterations that could explain their radioresistance, resistance was associated with reduced chromosomal instability, an association that was also observed in 529 human cancer cell lines. These data suggest that resistance to radiation is inherently present and associated with reduced chromosomal instability.