Association of MLH1 single nucleotide polymorphisms with clinical outcomes of first-line irinotecan-based chemotherapy in colorectal cancer

Colorectal Cancer Risk Loci: Prognostic Factors for Clinical Outcomes? A Systematic Review and Meta-Analysis

BACKGROUND

Several single nucleotide polymorphisms (SNPs) identified through genome-wide association studies (GWASs) on colorectal cancer (CRC) incidence are also shown as promising predictors of clinical outcomes in CRC patients. These genetic variants might help inform precision prognostic strategies by predicting disease progression, treatment response, and overall survival, thereby guiding more personalized treatment plans. However, conflicting evidence exists regarding their clinical relevance.

AIM

A systematic review and meta-analysis was performed to assess the potential of GWAS-identified SNPs in predicting CRC outcomes.

METHODS AND RESULTS

We conducted a comprehensive search of PubMed, Web of Science, Embase, and Cochrane databases up to 18 October 2024 for prospective studies that investigated the associations of CRC-related SNPs and polygenic risk scores (PRSs) built based on multiple SNPs with clinical outcomes. Quality of the included studies was assessed using the Newcastle-Ottawa Scale, and the heterogeneity was assessed by I2 index and Cochran's Q test. The final analysis included 22 studies with overall high quality and heterogeneity in several aspects (e.g., genetic models, ethnic background, and genetic signatures of CRC types). Among over 100 CRC risk-related loci, 12 SNPs were statistically associated with CRC clinical outcomes (mainly survival outcomes), which were replicated in multiple studies. Notably, rs9929218 and rs6983267, located in genes involved in processes of tumorigenesis, were linked to poor survival with hazard ratios (95% CIs) of 1.26 (1.12-1.42) under a recessive model and 1.33 (1.10-1.61) under an additive model, respectively, in the stratified analysis by genetic models. Besides, PRSs built based on survival-related SNPs were moderately associated with overall survival in CRC patients with hazard ratios exceeding 2.6 for each one-point increase in PRS.

CONCLUSIONS

Individual genetic variants and PRSs are predictive of CRC survival, and might serve as potential factors for risk stratification, which could help develop personalized treatment and surveillance strategies for CRC patients. However, the potential for false positives and the significant heterogeneity among studies that cannot be fully addressed in the current analysis due to limited data require a cautious interpretation of these findings. Large-scale studies are warranted to further explore and validate GWAS-identified SNPs for promising prognostic biomarkers in CRC patients while accounting for factors such as ethnic differences and tumor subtypes.

Predicting drug response and toxicity in metastatic colorectal cancer: the role of germline markers

INTRODUCTION

Despite the introduction of targeted agents leading to therapeutic advances, clinical management of patients with metastatic colorectal cancer (mCRC) is still challenged by significant interindividual variability in treatment outcomes, both in terms of toxicity and therapy efficacy. The study of germline genetic variants could help to personalize and optimize therapeutic approaches in mCRC.

AREAS COVERED

A systematic review of pharmacogenetic studies in mCRC patients published on PubMed between 2011 and 2021, evaluating the role of germline variants as predictive markers of toxicity and efficacy of drugs currently approved for treatment of mCRC, was perfomed.

EXPERT OPINION

Despite the large amount of pharmacogenetic data published to date, only a few genetic markers (i.e., DPYD and UGT1A1 variants) reached the clinical practice, mainly to prevent the toxic effects of chemotherapy. The large heterogeneity of available studies represents the major limitation in comparing results and identifying potential markers for clinical use, the role of which remains exploratory in most cases. However, the available published findings are an important starting point for future investigations. They highlighted new promising pharmacogenetic markers within the network of inflammatory and immune response signaling. In addition, the emerging role of previously overlooked rare variants has been pointed out.

Irinotecan or Oxaliplatin: Which is the First Move for the Mate?

OBJECTIVES

The aim of the present review is to discuss the potential link between RAS, BRAF and microsatellite instability (MSI) mutational patterns and chemotherapeutic agent efficacy [Irinotecan (IRI) vs. Oxaliplatin (OXA)], and how this can potentially influence the choice of the chemotherapy backbone.

METHODS

Following a review of the research literature, all pertinent articles published in the core journals were selected for the study. The inclusion criteria regarded relevant clinical and pre-clinical studies on the topic of interest (Relationship of OXA and IRI to KRAS/BRAF mutations and MSI).

RESULTS

Excision repair cross complementation group 1 (ERCC1) expression is inhibited by KRAS mutation, making tumor cells more sensitive to OXA. Results from OPUS, COIN and PRIME trials support that no conclusive data are available for BRAF mutant population because of the small number of patients. Enhanced IRI cytotoxicity to MSI cell lines is due to the participation of some of the mismatch repair (MMR) components in various DNA repair processes and their role in the maintenance of the pro-apoptotic effect of IRI and G2/M cell arrest.

CONCLUSION

OXA and IRI are indispensable drugs for mCRC treatment and their selection must be as careful as that of targeted agents. We suggest taking into consideration the interaction between known genomic alterations and OXA and IRI activity to personalize chemotherapy in mCRC patients.