Meta-analysis of fecal viromes demonstrates high diagnostic potential of the gut viral signatures for colorectal cancer and adenoma risk assessment.

INTRODUCTION: Viruses have been reported as inducers of tumorigenesis. Little studies have explored the impact of the gut virome on the progression of colorectal cancer. However, there is still a problem with the repeatability of viral signatures across multiple cohorts. OBJECTIVES: The present study aimed to reveal the repeatable gut vial signatures of colorectal cancer and adenoma patients and decipher the potential of viral markers in disease risk assessment for diagnosis. METHODS: 1,282 available fecal metagenomes from 9 published studies for colorectal cancer and adenoma were collected. A gut viral catalog was constructed via a reference-independent approach. Viral signatures were identified by cross-cohort meta-analysis and used to build predictive models based on machine learning algorithms. New fecal samples were collected to validate the generalization of predictive models. RESULTS: The gut viral composition of colorectal cancer patients was drastically altered compared with healthy, as evidenced by changes in some Siphoviridae and Myoviridae viruses and enrichment of Microviridae, whereas the virome variation in adenoma patients was relatively low. Cross-cohort meta-analysis identified 405 differential viruses for colorectal cancer, including several phages of Porphyromonas, Fusobacterium, and Hungatella that were enriched in patients and some control-enriched Ruminococcaceae phages. In 9 discovery cohorts, the optimal risk assessment model obtained an average cross-cohort area under the curve of 0.830 for discriminating colorectal cancer patients from controls. This model also showed consistently high accuracy in 2 independent validation cohorts (optimal area under the curve, 0.906). Gut virome analysis of adenoma patients identified 88 differential viruses and achieved an optimal area under the curve of 0.772 for discriminating patients from controls. CONCLUSION: Our findings demonstrate the gut virome characteristics in colorectal cancer and adenoma and highlight gut virus-bacterial synergy in the progression of colorectal cancer. The gut viral signatures may be new targets for colorectal cancer treatment. In addition, high repeatability and predictive power of the prediction models suggest the potential of gut viral biomarkers in non-invasive diagnostic tests of colorectal cancer and adenoma.

PD-1/PD-L1 Inhibitor Plus Chemotherapy Versus PD-1/PD-L1 Inhibitor in Microsatellite Instability Gastrointestinal Cancers: A Multicenter Retrospective Study.

PURPOSE: To investigate the efficacy of PD-1/PD-L1 inhibitors plus chemotherapy versus anti-PD-1/PD-L1 monotherapy in advanced microsatellite instability (MSI)/mismatch repair-deficient (dMMR) gastrointestinal cancers. METHODS: We retrospectively recruited patients with MSI/dMMR gastrointestinal cancer who received anti-PD-1/PD-L1 with or without chemotherapy and compared objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) of PD-1/PD-L1 inhibitor plus chemotherapy (chemo-anti-PD-1/PD-L1 group) and PD-1/PD-L1 inhibitor alone (anti-PD-1/PD-L1 group). Propensity score-based overlap weighting analysis was conducted to adjust the baseline covariable imbalance. Sensitivity analysis was performed to confirm the stability of the results by propensity score matching and multivariable Cox and logistic regression models. RESULTS: A total of 256 patients were eligible, with 68 and 188 receiving chemo-anti-PD-1/PD-L1 and anti-PD-1/PD-L1, respectively. The chemo-anti-PD-1/PD-L1 group showed significant improvements versus the anti-PD-1/PD-L1 group in ORR (61.8% v 38.8%; P = .001), DCR (92.6% v 74.5%; P = .002), PFS (median PFS [mPFS], not reached [NR] v 27.9 months; P = .004), and OS (median OS [mOS], NR v NR; P = .014). After overlap weighting, the improvements tended to be more significant with chemo-anti-PD-1/PD-L1 versus anti-PD-1/PD-L1 in ORR (62.5% v. 38.3%; P < .001), DCR (93.8% v 74.2%; P < .001), PFS (mPFS, NR v 26.0 months; P = .004), and OS (mOS, NR v NR; P = .010). These results were solidified through sensitivity analysis. CONCLUSION: Chemo-anti-PD-1/PD-L1 is superior to anti-PD-1/PD-L1 in MSI/dMMR gastrointestinal cancers with improved efficacy.

The Optimal Therapy after Progression on Immune Checkpoint Inhibitors in MSI Metastatic Gastrointestinal Cancer Patients: A Multicenter Retrospective Cohort Study.

BACKGROUND: In microsatellite instability (MSI)/mismatch repair-deficient (dMMR) gastrointestinal cancers, the optimum therapy after the progression of immune checkpoint inhibitors (ICIs) is yet unknown. Here, we compared the efficacy of programmed death 1 (PD1)/programmed death ligand-1 (PD-L1) inhibitors plus other therapy and chemotherapy with or without targeted therapy in MSI/dMMR gastrointestinal cancer patients after progression on anti-PD1/PD-L1 monotherapy. METHODS: We retrospectively recruited MSI/dMMR gastrointestinal cancer patients who had progressed on anti-PD1/PD-L1 monotherapy. Objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and PFS ratio (PFSr) were compared between patients who received anti-PD1/PD-L1 plus other therapy (ICI-plus group) and patients who received chemotherapy with or without targeted therapy (chemo-targeted group). RESULTS: In total, 26 and 25 patients were recruited in the ICI-plus group and chemo-targeted group, respectively. Significantly better DCR (80.8% vs. 44.0%, p = 0.007), PFS (median PFS 6.9 months vs. 3.0 months, p = 0.001), OS (median OS NR vs. 14.1 months, p = 0.043), and PFSr (2.4 vs. 0.9, p = 0.021), along with a numerically higher ORR (23.1% vs. 12.0%, p = 0.503) were observed in the ICI-plus group compared with the chemo-targeted group. Multivariate analyses identified the therapy regimen as an important prognostic factor in gastrointestinal cancers. CONCLUSIONS: Compared to conventional chemotherapy with or without targeted therapy, continuing anti-PD1/PD-L1 in combination with other treatments showed better clinical outcomes in MSI/dMMR gastrointestinal cancer patients who progressed on PD1/PD-L1 blockade, which should be validated prospectively in clinical trials.

Drosophila Caliban mediates G1-S transition and ionizing radiation induced S phase checkpoint.

Cell cycle progression is precisely regulated by diverse extrinsic and intrinsic cellular factors. Understanding the underlying mechanisms of cell cycle regulation is essential to address how normal development and tissue homeostasis are achieved. Here, we present a novel cell cycle regulator Caliban (Clbn), the Drosophila ortholog of human Serologically defined colon cancer antigen 1 (SDCCAG1) gene. We show that ionizing radiation induces expression of clbn, and over-expression of clbn blocks G1-to-S cell cycle transition in Drosophila, while flies loss of clbn have defective S phase checkpoint in response to irradiation. Mechanistically, induced expression of clbn suppressed E2F1 activity and down-regulates the DNA replication and expression of its downstream target cyclin E, a key regulator of G1-to-S transition. Meanwhile, clbn over-expression leads to upregulation of the CDK inhibitor Dacapo (Dap), and upregulated Dap is decreased when e2f1 is over-expressed. Furthermore, expression of clbn is down-regulated in cells with e2f1 over-expression or rbf1 knockdown, indicating that Clbn and E2F1 act antagonistically in mediating G1-to-S transition. Thus we provide genetic evidence that Clbn works together with E2F1 in regulating cell cycle progression, and Clbn is required for S phase cell cycle checkpoint in response to DNA damage.