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Molecular differentiation between complete and incomplete responders to neoadjuvant therapy in rectal cancer

ABSTRACT: Neoadjuvant chemoradiotherapy (nCRT) is the standard treatment for locally advanced rectal cancer, but less than half of patients have a clinical complete response to this treatment. To define the molecular features that are associated with response to neoadjuvant therapy, we generated and collected genomic and transcriptomic data from 712 cancers prior to treatment from our own data and from publicly available data. We found that patients with a complete response have decreased risk of local recurrence and future metastasis. We identified multiple differences in DNA mutations and transcripts between complete and incomplete responders. Complete responder tumors have a higher tumor mutation burden and many more significant co-occurring mutations than the incomplete responder tumors. In addition, mutations in DNA repair genes (across multiple mechanisms of repair) were enriched in complete responders and they also had lower expression of these genes indicating that defective DNA repair is associated with complete response to nCRT. Using logistic regression, we identified three significant predictors of complete response: tumor size, mutations within specific network genes, and the existence of three or more concurrent mutations. In tumors that do not completely respond to nCRT, abnormal cell-cell interaction and increased cancer associated fibroblasts were associated with recurrence. Additionally,gene expression analysis identified a subset of immune hot tumors with worse outcomes and upregulation of immune checkpoint proteins. Overall, our study provides a comprehensive understanding of the molecular features associated with response to nCRT and the molecular differences in non-responder tumors that later reoccur. This knowledge may provide critical insight into the development of precision therapy for rectal cancer.

ORGANISM(S): Homo sapiens

PROVIDER: GSE242786 | GEO | 2024/08/09

REPOSITORIES: GEO

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Project description:Background: Neoadjuvant chemoradiotherapy (NCRT) is the treatment of choice in advanced rectal cancer, even though there are many patients who will not benefit from it. There are still no effective methods for predicting which patients will respond or not. The present study aimed to define the genomic profile of rectal tumors and to identify alterations that are predictive of response in order to optimize therapeutic strategies. Methods: Forty-eight candidates for NCRT were recruited and their pretherapy biopsies analyzed by array Comparative Genomic Hybridization (aCGH). Pathologic response was evaluated by tumor regression grade (TRG).Results: Both Smoothing and Hidden Markov Model (HMM) approaches identified similar alterations, with a prevalence of DNA gains. Non responsive patients had a different alteration profile from responsive ones, with a higher number of genome changes mainly located on 2q21, 7q21, 7q36, 13q12, 13q32-34, 16p13, 17p12 chromosomal regions. Conclusion: This exploratory study suggests that an in depth characterization of chromosomal alterations by aCGH would provide useful predictive information about response to NCRT and help to optimize therapy in rectal cancer patients. 48 samples included in the study were analyzed on whole genome BAC arrays with the aim to characterize genomic alterations and correlate them with the tumor response to therapy. The case series was composed by 15%,81% and 4% of uT2, uT3 and uT4 tumors, respectively. At the diagnosis 56% of patients had uN0 tumors and 44% uN+. 30%,13%, 23% and 34% of patients reached/mantained respectively ypT0, ypT1, ypT2 and ypT3. With regard to response to NCRT, according to TRG criteria proposed by Dworak, two group were defined: non responders (TRG0-2= 56%) and responders (TRG3-4=44%). Clinical and pathological parameters: uT: pre-therapy stage determined by ultrasounds techniques uN: pre-therapy lymph node status determined by ultrasounds techniques ypT: pathologic stage after a neoadjuvant treatment ypN: pathologic lymph node status after a neoadjuvant treatment

Project description:Purpose: Neoadjuvant chemoradiotherapy (nCRT) is the standard treatment forpatients with locally advanced rectal cancer. However, little is known about the effect of nCRT in the mutational landscape and intratumoral genetic heterogeneity (ITGH) of rectal tumors. Moreover, response to nCRT vary substantially among patients and the genetic determinants of treatment response are not fully understood. Here, we sought to determine the impact of nCRT in the mutational landscape and ITGH of rectal tumors and to identify putative drivers of therapeutic resistance. Patients and Methods: We analyzed whole-exome sequencing (WES) and clinical data from 79 primary non-treated rectal cancers obtained from The Cancer Genome Atlas (TCGA). We also compared the mutational landscape of a matched set of peripheral blood cells, irradiated tumor-adjacent colonic mucosa and pre and post-treatment tumor samples to determine the iatrogenic effects of nCRT and its impact in tissue genetic heterogeneity. Finally, we performed WES of 7 matched pre and post-treatment tumor samples to examine how nCRT affects the clonal architecture of rectal tumors. Results: We show that rectal tumors exhibit remarkable ITGH, which increases with disease progression. We also show that nCRT, per se, does not introduce novel somatic mutations, nor alters the clonal architecture of the irradiated colonic mucosa. Instead, we show that it acts as a potent selective pressure, favoring the expansion of tumor cell subpopulations more prone to resist therapy and increasing ITGH in the residual tumor. Conclusion: Our results reveal the highly heterogeneous and dynamic clonal architecture of rectal tumors undergoing nCRT. Our results also uncover putative genetic determinants of response to nCRT and a possible role for ITGH in predicting treatment outcome.

Project description:The incorporation of chemoradiation prior to resection of the tumour has revolutionized the management of locally advanced rectal cancer. However, a large proportion of these patients are resistant to preoperative treatment schedule. We recently reported that c-Myc gene expression correlates negatively with this resistance in patients with rectal cancer. In this study, we carried out integrated analysis of miRNA and mRNA expression profiling in 45 pre-treatment rectal tumour. Further, expression of miRNAs and c-Myc, and their relationship with clinicopathological factors and patient survival was analysed. As a result, we found that 12 miRNAs were differentially expressed between responder and non-responder rectal cancer patients. Functional classification revealed an association between differentially expressed miRNAs and c-Myc. Subsequent quantitative real-time PCR results showed that both, miRNA-148 and miRNA-375 levels were significantly lower in responder compared to non-responder patients. Notably, the higher level of miRNA-375 was significantly negatively correlated with c-Myc. These results suggest that miRNA-375 and its targeted c-Myc play an important role as predictive biomarker of response to neoadjuvant treatment in patients with locally advanced rectal cancer, but still not suitable for prognosis. Pre-treatment biopsies of 22 patients with LARC were prospectively collected and freshly frozen according to an institutional board-approved protocol. Tumour response was assessed in surgical specimens by pathological examination based on the semi-quantitative tumour regression grading (TRG) system described by Mandard in 1994[36]: TRG1 and TRG2 scores were considered responders, whereas TRG3, TRG4, and TRG5 were classified as non-responders. The inclusion criteria were: histologically proven rectal tumour at a clinical stage UICC II-III (cT3-4/and or N positive), following endorectal ultrasound and/or MRI scan. Patients were excluded if they had the tumour located above 13 cm from the anal verge by rigid rectoscopy, synchronic colonic cancer assessed by colonoscopy, distant metastases by 18FDG PET-CT scan, and suspicion of hereditary colorectal cancer. All patients subsequently received a total dose of 50.4Gy of radiation (28 fractions of 1.8Gy) associated with capecitabine (oral form of 5-FU) with or without oxaliplatine, according to our Hospital Clinical Practice Guidelines. Standardized Surgery was performed, including total mesorectal excision, following an interval of 8-10 weeks after completion of CT/RT.

Project description:Importance: Neoadjuvant chemoradiotherapy (CRT) is the standard of care for advanced rectal cancer. Yet, predicting response to CRT remains an unmet clinical challenge. Objective: To investigate the transcriptomic determinants to predict response to neoadjuvant CRT and survival in patients with advanced rectal cancer. Design: A single-center, retrospective, cohort study. Setting: A comprehensive cancer center. Participants: Pre-treatment biopsies from 298 patients with rectal cancer, who were later treated with neoadjuvant CRT between 2004 and 2020, were analyzed by RNA sequencing. Main measures and outcomes: Transcriptional subtyping was performed by consensus molecular subtype (CMS) classification. Immune cell infiltration was assessed using MCP-counter scores and single-sample gene set enrichment analysis (ssGSEA). Patients with surgical specimens of tumor regression grade (TRG) 3-4 or who were managed by the watch-and-wait approach for more than 3 years were defined as good responders. Results: Patients classified as CMS1 (6.4%) had a significantly higher rate of good responders; albeit survival was comparable among the four subtypes. Good responders exhibited an enrichment in various immune-related pathways (IFNg and a responses, allograft rejection, IL6 STAT3 signaling during acute phase response, and inflammation), as determined by ssGSEA. MCP-counter scores for cytotoxic lymphocytes were significantly higher for good responders than non-responders (p = 0.0003), and significantly higher for responders than non-responders in GSE109057 (p = 0.0137), GSE87211 (p = 0.0092), and GSE45404 (p = 0.0327) datasets. Cytotoxic lymphocyte MCP-counter score was thus considered an independent predictor of response to CRT, as determined in the multivariable Cox analysis (OR 3.810 [95% CI 1.820-7.970]; p = 0.0004). Multivariable Cox analysis, including post-operative pathological factors, revealed cytotoxic lymphocyte MCP-counter score to be independently associated with recurrence-free survival (HR 0.382 [95% CI 0.158-0.923]; p = 0.0325) and overall survival (HR 0.157 [95% CI 0.030-0.827]; p = 0.0290). ssGSEA showed significantly higher levels of four subpopulations of cytotoxic cells (effector memory CD8 T, natural killer T, natural killer, and activated CD8 T cells) among good responders than non-responders. Conclusions and Relevance: Cytotoxic lymphocyte score, as computed by RNA sequencing, could be a useful marker for predicting response to CRT and survival among patients with rectal cancer.

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Molecular differentiation between complete and incomplete responders to neoadjuvant therapy in rectal cancer

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