Inflammation is a common medical complication in colorectal cancer (CRC) patients, which plays significant roles in tumor progression and immunosuppression. However, the influence of inflammatory conditions on the tumor response to immune checkpoint inhibitors (ICI) is incompletely understood. Here we show that in a patient with high microsatellite instability (MSI-H) CRC and a local inflammatory condition, the primary tumor progresses but its liver metastasis regresses upon Pembrolizumab treatment. In silico investigation prompted by this observation confirms correlation between inflammatory conditions and poor tumor response to PD-1 blockade in MSI-H CRCs, which is further validated in a cohort of 62 patients retrospectively enrolled to our study. Inhibition of local but not systemic immune response is verified in cultures of paired T cells and organoid cells from patients. Single-cell RNA sequencing suggests involvement of neutrophil leukocytes via CD80/CD86-CTLA4 signaling in the suppressive immune microenvironment. In concordance with this finding, elevated neutrophil-to-lymphocyte ratio indicates inhibited immune status and poor tumor response to ICIs. Receiver operating characteristic curve further demonstrates that both inflammatory conditions and a high NLR could predict a poor response to ICIs in MSI- CRCs, and the predictive value could be further increased when these two predictors are combined. Our study thus suggests that inflammatory conditions in MSI-H CRCs correlate with resistance to ICIs through neutrophil leukocyte associated immunosuppression and proposes both inflammatory conditions and high neutrophil-to-lymphocyte ratio as clinical features for poor ICI response.

Resistance to chemotherapy remains the major cause of treatment failure in patients with colorectal cancer (CRC). Here, we identified TRIM25 as an epigenetic regulator of oxaliplatin (OXA) resistance in CRC. The level of TRIM25 in OXA-resistant patients who experienced recurrence during the follow-up period was significantly higher than in those who had no recurrence. Patients with high expression of TRIM25 had a significantly higher recurrence rate and worse disease-free survival than those with low TRIM25 expression. Downregulation of TRIM25 dramatically inhibited, while overexpression of TRIM25 increased, CRC cell survival after OXA treatment. In addition, TRIM25 promoted the stem cell properties of CRC cells both in vitro and in vivo. Importantly, we demonstrated that TRIM25 inhibited the binding of E3 ubiquitin ligase TRAF6 to EZH2, thus stabilizing and upregulating EZH2, and promoting OXA resistance. Our study contributes to a better understanding of OXA resistance and indicates that inhibitors against TRIM25 might be an excellent strategy for CRC management in clinical practice.

β2-microglobulin (B2M) and Janus kinases 1 and 2 (JAK1/2) mutations have been suggested as genetic mechanisms of immune evasion for anti–programmed cell death protein 1 (PD-1) therapy. Whether B2M and JAK1/2 lose-of-function mutation can cause primary resistance to anti-PD-1 therapy in colorectal carcinoma (CRC) patients remains controversial. Here, we sought to compare the efficacy of anti-PD-1 therapy in DNA mismatch repair deficient/microsatellite instability–high CRC patients with or without B2M or JAK1/2 mutations. Thirty-Five CRC patients who received anti-PD-1 therapy were enrolled in this study. All tumor samples underwent next-generation sequencing. The clinical and molecular data from 110 CRC patients sequenced with the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) assay and accessed through cBioportal were also analyzed in this study. Of the 35 CRC patients from our center, 10 (28.6%) had a B2M loss-of-function mutation, and 8 (22.9%) had a JAK1/2 loss-of-function mutation. Compared with B2M wild-type CRCs, B2M-mutated CRCs did not show a higher frequency of resistance to anti-PD-1 therapy (P=0.71). There was even better response to anti-PD-1 therapy in patients with JAK1/2 mutation than in those without (P=0.015). Of the 110 CRC patients in the MSK-IMPACT datasets, 13 (11.8%) had a B2M mutation, and 15 (13.6%) had a JAK1/2 mutation. After analyzing the response to anti-PD-1 therapy in these 110 patients, we found similar results (P=0.438 and 0.071, respectively). Moreover, patients with B2M or JAK1/2 mutation had a lower tumor mutational burden score compared with those without. B2M and JAK1/2 loss-of-function mutations occur frequently in microsatellite instability–high CRC. Our study demonstrated that patients with CRC harboring B2M or JAK1/2 mutations should not be excluded from anti-PD-1 therapy.

Background: The number of colorectal cancer liver metastases (CRLMs) is usually considered a contradictory indicator to surgical resection. However, some patients with initially unresectable CRLMs can receive radical local treatment after conversion therapy. This study aimed to evaluate the effect of radical local treatment after conversion therapy and the prognosis of patients with more than 10 initially unresectable CRLMs.Methods: Data for a total of 229 patients with initially unresectable CRLMs were retrospectively reviewed between December 2012 and January 2020. Among these patients, 107 had ≥10 CRLMs, and 122 had <10 CRLMs. Overall survival (OS) and progression‐free survival (PFS) were used to reflect the prognosis of different groups of patients. Conversion therapy was defined as an initially unresectable liver metastasis converted into an R0 resectable lesion after systemic chemotherapy. Radical local treatment included hepatectomy and radiofrequency ablation (RFA).Results: Patients with ≥10 CRLMs had a lower conversion rate (42.7% vs. 56.6%, p = 0.001). Baseline clinical N stage 1–2, ≥8 first‐line chemotherapy courses, and stable disease (SD) according to the Response Evaluation Criteria in Solid Tumours (RECIST) were independent factors predictive of conversion failure. Primary tumour location in the right colon, RECIST response of SD, and the absence of targeted therapy were independent factors predictive of unfavourable OS. The survival curves revealed that the OS of patients with or without conversion could be distinguished only among patients with <10 CRLMs (89.9% [95% CI, 82.5%–98.0%] vs. 58.9% [95% CI, 45.2%–76.7%], p < 0.001); this cut‐off point could also distinguish patients with a successful conversion outcome according to OS (89.9% [95% CI, 82.5–98.0%] vs. 58.2% [95% CI, 42.2–80.4%], p = 0.008).Conclusion: For CRLMs ≥ 10, patients with a successful conversion outcome cannot be distinguished from those without successful conversion outcome according to OS. Thus, conversion therapy with the intent to perform radical local treatment may not be suitable for patients with 10 or more liver metastases from colorectal cancer.

This study investigates advanced colorectal cancer (CRC), focusing on its tendency for distant metastasis and chemotherapy resistance. It highlights the importance of PANoptosis, a cell death pathway, and the role of the Receptor-interacting serine/threonine-protein kinase (RIPK) family in tumor progression. RIPK4’s tissue-specific functions in cancer cell behavior are emphasized, including its influence on invasion, migration, and oxidative stress resistance. The study reveals the critical balance of reactive oxygen species (ROS) in cancer cells, linked to antioxidant defenses and NADPH production for survival. A key finding is the connection between TP53 mutations in CRC and increased RIPK4 expression, which enhances MTHFD1 phosphorylation, boosts NADPH production, reduces ROS, and promotes resistance to PANoptosis, leading to metastasis. The research identifies the molecular basis of CRC metastasis, showing how RIPK4 regulates MTHFD1 to resist PANoptosis, offering new therapeutic targets for metastatic CRC and potential improvements in patient outcomes.