This study provides a novel combination strategy for immunotherapy in pMMR/MSS colorectal cancer, suggesting that the PI3K/AKT and DNA repair pathways may serve as key predictive biomarkers, offering significant reference value for research into mechanisms of resistance to immunotherapy.
Literature Overview
The article titled “First-line Nivolumab plus FOLFOXIRI/Bevacizumab in advanced RAS/BRAF-mutated colorectal cancer: efficacy, safety and biomarker discovery from the phase II NIVACOR trial”, published in the journal Nature Communications, systematically investigates the anti-tumor activity, safety, and potential biomarkers of nivolumab combined with FOLFOXIRI/bevacizumab as a first-line treatment in patients with RAS/BRAF-mutated metastatic colorectal cancer (mCRC). The study not only achieved its primary endpoint of objective response rate (ORR), but also revealed molecular features associated with treatment efficacy through comprehensive genomic and transcriptomic analyses, offering new insights into immunotherapy for pMMR/MSS mCRC.Background Knowledge
Metastatic colorectal cancer (mCRC) is one of the leading causes of cancer-related deaths worldwide, with approximately 40–50% of cases harboring RAS or BRAF mutations, which are associated with poor prognosis. Although dMMR/MSI mCRC tumors respond well to PD-1 inhibitor monotherapy, the majority pMMR/MSS tumors show extremely low response rates to immune checkpoint inhibitors alone, representing a major bottleneck in current immunotherapy. Previous studies suggest that chemotherapy and anti-angiogenic agents may enhance T-cell infiltration by modulating the tumor microenvironment, thereby overcoming the “cold” tumor phenotype. Therefore, combining immune checkpoint inhibitors with cytotoxic chemotherapy and anti-VEGF therapy represents a rational strategy to improve outcomes in pMMR/MSS mCRC. However, the lack of reliable predictive biomarkers limits precise patient selection, necessitating integrated multi-omics approaches to uncover underlying mechanisms. This study explores the therapeutic potential of nivolumab combined with FOLFOXIRI/bevacizumab in RAS/BRAF-mutated mCRC and systematically analyzes the molecular features associated with response and resistance.
Research Methods and Experiments
The study employed a single-arm, multicenter phase II design (NCT04072198), enrolling 73 treatment-naïve patients with RAS/BRAF-mutated mCRC who received nivolumab in combination with FOLFOXIRI/bevacizumab. The primary endpoint was ORR assessed by independent central imaging review; secondary endpoints included PFS, OS, DoR, and safety. To explore biomarkers, comprehensive genomic profiling (CGP) and RNA sequencing (RNAseq) were performed on FFPE tumor samples from 68 patients, with survival analyses integrated with clinical data. CGP was conducted using the Oncomine Comprehensive Plus Assay to detect genomic alterations and assess TMB and MSI status; RNAseq enabled differential expression and pathway enrichment analyses, with stratification based on consensus molecular subtypes (CMS) and the novel iCMS classification system.Key Conclusions and Perspectives
Research Significance and Prospects
This study confirms the high response rate of triplet therapy in refractory RAS/BRAF-mutated mCRC, challenging the traditional view that pMMR/MSS CRC is resistant to immunotherapy and offering a new treatment option for these patients. More importantly, through integrated multi-omics analysis, the study identifies the PI3K/AKT and DNA repair pathways as potential biomarkers, suggesting that targeting these pathways could enhance immunotherapy sensitivity and advance precision immunotherapy.
From a drug development perspective, this study provides mechanistic rationale for combination therapies, such as pairing PI3K inhibitors with PD-1 inhibitors. Additionally, the discovery of RES and SENS signatures offers candidate gene lists for the clinical development of predictive NGS panels, facilitating personalized treatment. Moreover, although the iCMS classification alone did not significantly stratify PFS, its combination with RES/SENS showed stronger predictive power, suggesting that single-cell-level molecular subtyping may be more suitable for guiding immunotherapy.
Conclusion
This study demonstrates through the NIVACOR phase II trial that nivolumab combined with FOLFOXIRI/bevacizumab achieves high objective response rates and manageable safety in patients with RAS/BRAF-mutated mCRC, significantly improving upon traditional chemotherapy outcomes. Its remarkable efficacy in the pMMR/MSS population challenges the long-held belief that these tumors are unresponsive to immunotherapy. By integrating CGP and RNAseq data, the study reveals that activation of the PI3K/AKT pathway is positively associated with treatment response, while dysregulation in DNA repair pathways may drive resistance, opening new avenues for biomarker-driven precision immunotherapy. Furthermore, the upregulation of chemokine signaling and immune cell chemotaxis pathways highlights tumor immune microenvironment remodeling as a key mechanism. These findings not only lay the foundation for future phase III validation trials but also provide theoretical support for developing novel combination strategies (e.g., PD-1 inhibitors plus PI3K inhibitors). From bench to bedside, this study advances the transition from “one-size-fits-all” therapy to individualized immunotherapy regimens based on molecular profiles, potentially improving long-term survival in mCRC patients and becoming a cornerstone in optimizing the care of pMMR/MSS colorectal cancer.
