Primary resistance to immunotherapy in patients with a dMMR/MSI metastatic gastrointestinal cancer: who is at risk? An AGEO real-world study.

BACKGROUND: The outstanding efficacy of immunotherapy in metastatic dMMR/MSI gastro-intestinal (GI) cancers has led to a rapid increase in the number of patients treated. However, 20-30% of patients experience primary resistance to immune checkpoint inhibitors (ICIPR) and need better characterization. METHODS: This AGEO real-world study retrospectively analyzed the efficacy and safety of ICIs and identified clinical variables associated with ICIPR in patients with metastatic dMMR/MSI GI cancers treated with immunotherapy between 2015 and 2022. RESULTS: 399 patients were included, 284 with colorectal cancer (CRC) and 115 with non-CRC, mostly treated by an anti-PD(L)1 (88.0%). PFS at 24 months was 55.8% (95CI [50.8-61.2]) and OS at 48 months was 59.1% (95CI [53.0-65.9]). ORR was 51.0%, and 25.1% of patients were ICIPR. There was no statistical difference in ORR, DCR, PFS, or OS between CRC and non-CRC groups. In multivariable analysis, ICIPR was associated with ECOG-PS ≥ 2 (OR = 3.36), liver metastases (OR = 2.19), peritoneal metastases (OR = 2.00), ≥1 previous line of treatment (OR = 1.83), and age≤50 years old (OR = 1.76). CONCLUSION: These five clinical factors associated with primary resistance to ICIs should be considered by physicians to guide treatment choice in GI dMMR/MSI metastatic cancer patients.

Wnt, glucocorticoid and cellular prion protein cooperate to drive a mesenchymal phenotype with poor prognosis in colon cancer.

BACKGROUND: The mesenchymal subtype of colorectal cancer (CRC), associated with poor prognosis, is characterized by abundant expression of the cellular prion protein PrPC, which represents a candidate therapeutic target. How PrPC is induced in CRC remains elusive. This study aims to elucidate the signaling pathways governing PrPC expression and to shed light on the gene regulatory networks linked to PrPC. METHODS: We performed in silico analyses on diverse datasets of in vitro, ex vivo and in vivo models of mouse CRC and patient cohorts. We mined ChIPseq studies and performed promoter analysis. CRC cell lines were manipulated through genetic and pharmacological approaches. We created mice combining conditional inactivation of Apc in intestinal epithelial cells and overexpression of the human prion protein gene PRNP. Bio-informatic analyses were carried out in two randomized control trials totalizing over 3000 CRC patients. RESULTS: In silico analyses combined with cell-based assays identified the Wnt-ß-catenin and glucocorticoid pathways as upstream regulators of PRNP expression, with subtle differences between mouse and human. We uncover multiple feedback loops between PrPC and these two pathways, which translate into an aggravation of CRC pathogenesis in mouse. In stage III CRC patients, the signature defined by PRNP-CTNNB1-NR3C1, encoding PrPC, ß-catenin and the glucocorticoid receptor respectively, is overrepresented in the poor-prognosis, mesenchymal subtype and associates with reduced time to recurrence. CONCLUSIONS: An unleashed PrPC-dependent vicious circle is pathognomonic of poor prognosis, mesenchymal CRC. Patients from this aggressive subtype of CRC may benefit from therapies targeting the PRNP-CTNNB1-NR3C1 axis.

Clinical value of sequential circulating tumor DNA analysis using next-generation sequencing and epigenetic modifications for guiding thermal ablation for colorectal cancer metastases: a prospective study.

INTRODUCTION: While thermal ablation is now a standard treatment option for oligometastatic colorectal cancer patients, selecting those who will benefit most from locoregional therapies remains challenging. This proof-of-concept study is the first to assess the feasibility of routine testing of ctDNA before and after thermal ablation with curative intent, analyzed by next-generation sequencing (NGS) and methylation specific digital droplet PCR (ddPCR). Our prospective study primary objective was to assess the prognostic value of ctDNA before thermal ablation. METHODS: This single-center prospective study from November 2021 to June 2022 included colorectal cancer patients referred for curative-intent thermal ablation. Cell-free DNA was tested at different time points by next-generation sequencing and detection of WIF1 and NPY genes hypermethylation using ddPCR. The ctDNA was considered positive if either a tumor mutation or hypermethylation was detected; recurrence-free survival was used as the primary endpoint. RESULTS: The study enrolled 15 patients, and a total of 60 samples were analyzed. The median follow-up after ablation was 316 days, and median recurrence-free survival was 250 days. CtDNA was positive for 33% of the samples collected during the first 24 h. The hazard ratio for progression according to the presence of baseline circulating tumor DNA was estimated at 0.14 (CI 95%: 0.03-0.65, p = 0.019). The dynamics are provided, and patients with no recurrence were all negative at H24 for ctDNA. DISCUSSION: This study shows the feasibility of routine testing of ctDNA before and after thermal ablation with curative intent. We report that circulating tumor DNA is detectable in patients with low tumor burden using 2 techniques. This study emphasizes the potential of ctDNA for discerning patients who are likely to benefit from thermal ablation from those who may not, which could shape future referrals. The dynamics of ctDNA before and after ablation shed light on the need for further research and larger studies.

Upfront progression under pembrolizumab followed by a complete response after encorafenib and cetuximab treatment in BRAF V600E-mutated and microsatellite unstable metastatic colorectal cancer patient: A case report.

Two new treatments have recently become standard care for patients with metastatic colorectal cancer (mCRC): encorafenib (BRAF inhibitor) associated with cetuximab (anti-EGFR) in the second or third line of chemotherapy for BRAF V600E tumors, and pembrolizumab (an anti PD-1 immune checkpoint inhibitor) for tumors harboring microsatellite instability (MSI)-high and/or deficient mismatch repair (dMMR). Furthermore, 30% of BRAF V600E mutated mCRC are MSI/dMMR through a sporadic hypermethylation of the promoter of hMLH1. We report here, for the first time, the case of a patient with BRAF V600E, PIK3CA, and SMAD4 mutated and dMMR/MSI mCRC, in whom we observed an atypical response pattern under the sequence of pembrolizumab followed by the doublet encorafenib and cetuximab treatment. The patient was progressive after a single cycle of pembrolizumab followed by a rapid complete response after only 2 months of treatment with encorafenib and cetuximab, discovered during R0 cytoreduction surgery for peritoneal carcinomatosis.

Does neoadjuvant FOLFOX chemotherapy improve the prognosis of high-risk Stage II and III colon cancers? Three years' follow-up results of the PRODIGE 22 phase II randomized multicentre trial.

AIM: Neoadjuvant chemotherapy has proven valuable in locally advanced resectable colon cancer (CC) but its effect on oncological outcomes is uncertain. The aim of the present paper was to report 3-year oncological outcomes, representing the secondary endpoints of the PRODIGE 22 trial. METHOD: PRODIGE 22 was a randomized multicentre phase II trial in high-risk T3, T4 and/or N2 CC patients on CT scan. Patients were randomized between 6 months of adjuvant FOLFOX (upfront surgery) or perioperative FOLFOX (four cycles before surgery and eight cycles after; FOLFOX perioperative). In wild-type RAS patients, a third arm testing perioperative FOLFOX-cetuximab was added. The primary endpoint was the tumour regression grade. Secondary endpoints were 3-year overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS) and time to recurrence (TTR). RESULTS: Overall, 120 patients were enrolled. At interim analysis, the FOLFOX-cetuximab arm was stopped for futility. The remaining 104 patients represented our intention-to-treat population. In the perioperative group, 96% received the scheduled four neoadjuvant cycles and all but one had adjuvant FOLFOX for eight cycles. In the control arm, 38 (73%) patients received adjuvant FOLFOX. The median follow-up was 54.3 months. Three-year OS was 90.4% in both arms [hazard ratio (HR) = 0.85], 3-year DFS, RFS and TTR were, respectively, 76.8% and 69.2% (HR=0.94), 73% and 69.2% (HR = 0.86) and 82% and 72% (HR = 0.67) in the perioperative and control arms, respectively. Forest plots did not show any subgroup with significant difference for survival outcomes. No benefit from adding cetuximab was observed. CONCLUSION: Perioperative FOLFOX has no detrimental effect on long-term oncological outcomes and may be an option for some patients with locally advanced CC.

What is the Best Therapeutic Strategy for Metachronous Resectable Colorectal Liver Metastases After Adjuvant Oxaliplatin-Based Chemotherapy? A Multidisciplinary Inter-Group Survey.

BACKGROUND: To report the current clinical practice of French physicians for metachronous resectable liver metastasis (LM) occurring after a FOLFOX adjuvant chemotherapy for primary cancer. METHODS: Twenty four clinical situations were proposed to a panel of experts via 4 learned societies. Clinical situations varied according time of recurrence (early between 6 and 12 month or > 12 month), extension of LM (limited ≤ 2 or extended > 2 lesions), presence of a neuropathy or not, and of a RAS or BRAF mutation. RESULTS: A total of 157 physicians participated in this study. A consensus was reached in 17 (71%) clinical situations. For an early limited recurrence, whatever presence of neuropathy, the preferred therapeutic approach (45%) was upfront surgery. For an early extended recurrence, whatever presence of neuropathy, there was a consensus (64%) for a preoperative chemotherapy by FOLFIRI + biologic agent. For a late recurrence without neuropathy, there was a consensus (50%) for a preoperative FOLFOX chemotherapy, whatever the extension of LM. For a late recurrence with neuropathy, upfront surgery was chosen (52%) for limited LM, and preoperative chemotherapy by FOLFIRI + biologic agent (73%) for extended LM. No response was influenced by the RAS mutation status. There was a strong consensus for intensified preoperative chemotherapy in all clinical situations for BRAF-mutated LM. CONCLUSIONS: This national survey provides an overview of the practice patterns in the treatment of LM occurring after adjuvant FOLFOX for primary. It could be a basis to establish expert's recommendations for the clinical practice.

Clinical Challenges of Consensus Molecular Subtype CMS4 Colon Cancer in the Era of Precision Medicine.

Over the past decade, our understanding of the diversity of colorectal cancer has expanded significantly, raising hopes of tailoring treatments more precisely for individual patients. A key achievement in this direction was the establishment of the consensus molecular classification, particularly identifying the challenging consensus molecular subtype (CMS) CMS4 associated with poor prognosis. Because of its aggressive nature, extensive research is dedicated to the CMS4 subgroup. Recent years have unveiled molecular and microenvironmental features at the tissue level specific to CMS4 colorectal cancer. This has paved the way for mechanistic studies and the development of preclinical models. Simultaneously, efforts have been made to easily identify patients with CMS4 colorectal cancer. Reassessing clinical trial results through the CMS classification lens has improved our understanding of the therapeutic challenges linked to this subtype. Exploration of the biology of CMS4 colorectal cancer is yielding potential biomarkers and novel treatment approaches. This overview aims to provide insights into the clinico-biological characteristics of the CMS4 subgroup, the molecular pathways driving this subtype, and available diagnostic options. We also emphasize the therapeutic challenges associated with this subtype, offering potential explanations. Finally, we summarize the current tailored treatments for CMS4 colorectal cancer emerging from fundamental and preclinical studies.

Early-Onset colorectal Cancer: From the laboratory to the clinic.

Colorectal cancer that occurs before age of 50 is defined as Early-Onset Colorectal Cancer (EOCRC). Its incidence has worryingly increased since the late 90 s and is expected to keep rising in the next future, despite Late-Onset CRC (LOCRC) is decreasing worldwide. Because of this, there is an urgent need to better understand this subset of patients in order to give them the best treatment possible. However, most of the literature is retrospective and often discordant. In this review, we aim to provide a general overview of the issue, endeavoring to highlight the current available knowledge. We decided to move from the beginning, investigating risk factors and inheritance, passing through diagnosis and clinical aspects, and to conclude with the translational part, focusing on the biology of the tumor. However, lot of questions remain open, including screening age and prognosis. Indeed, young patients tend to be treated more aggressively, even if a survival benefit has not been proven yet. Every clinician should be aware of the best practice for young people, and more translational studies are awaited in order to clarify is EOCRC represents a distinct biological entity.

Diagnosis and treatment of bacterial peritonitis in patients with gastrointestinal cancer: an observational multicenter study.

Background: Bacterial peritonitis (BP) in patients with gastrointestinal (GI) cancer has been poorly described, and its prevalence is unknown. Objectives: This study aimed to evaluate in patients with both GI cancer and ascites the prevalence of BP, associated features, mechanisms, prognosis, and the diagnostic performance of neutrophil count in ascites. Design: A retrospective, multicenter, observational study. Methods: All patients with GI cancer and ascites who underwent at least one paracentesis sample analyzed for bacteriology over a 1-year period were included. BP was defined by a positive ascites culture combined with clinical and/or biological signs compatible with infection. Secondary BP was defined as BP related to a direct intra-abdominal infectious source. Results: Five hundred fifty-seven ascites from 208 patients included were analyzed. Twenty-eight patients had at least one episode of BP and the annual prevalence rate of BP was 14%. Among the 28 patients with BP, 19 (65%) patients had proven secondary BP and 17 (59%) patients had multi-microbial BP, mainly due to Enterobacterales. A neutrophil count greater than 110/mm3 in ascites had negative and positive predictive values of 96% and 39%, respectively, for the diagnosis of BP. The median survival of patients with BP was 10 days (interquartile range 6-40) after the diagnosis. Conclusion: BP is not rare in patients with GI cancer and is associated with a poor short-term prognosis. When a patient with GI cancer is diagnosed with BP, a secondary cause should be sought. Further studies are needed to better define the best management of these patients.