Functional TP53 mutations have no impact on response to cytotoxic agents in metastatic colon cancer

Tumor location matters, next generation sequencing mutation profiling of left-sided, rectal, and right-sided colorectal tumors in 552 patients

Despite the introduction of new molecular classifications, advanced colorectal cancer (CRC) is treated with chemotherapy supplemented with anti-EGFR and anti-VEGF targeted therapy. In this study, 552 CRC cases with different primary tumor locations (250 left side, 190 rectum, and 112 right side) were retrospectively analyzed by next generation sequencing for mutations in 50 genes. The most frequently mutated genes were TP53 in left-sided tumors compared to right-sided tumors and BRAF in right-sided tumors compared to left-sided tumors. Mutations in KRAS, NRAS, and BRAF were not detected in 45% of patients with left-sided tumors and in 28.6% of patients with right-sided tumors. Liver metastases were more common in patients with left-sided tumors. Tumors on the right side were larger at diagnosis and had a higher grade (G3) than tumors on the left. Rectal tumors exhibit distinctive biological characteristics when compared to left-sided tumors, including a higher absence rate of KRAS, NRAS, and BRAF mutations (47.4% in rectal versus 42.8% in left-sided tumors). These rectal tumors are also unique in their primary metastasis site, which is predominantly the lungs, and they have varying mutation rates, particularly in genes such as BRAF, FBXW7, and TP53, that distinguish them from tumors found in other locations. Primary tumor location has implications for the potential treatment of CRC with anti-EGFR therapy.

The prognostic role of p53 mutations in metastatic colorectal cancer: a systematic review and meta-analysis

INTRODUCTION

P53 is one of the most frequently mutated genes in colorectal cancer (CRC). The present study was undertaken to provide a solid estimate of the prognostic value of p53 mutations in metastatic CRC patients.

METHODS

This meta-analysis was done in accordance to the Preferred Reporting Item For Systematic Reviews and Meta-Analysis 2020 guidelines. Studies in English published in the last ten years were searched through PubMed and Google Scholar. Final selection criteria were: 1) association with overall survival, 2) presence of Hazard Ratios (HRs) with 95% Confidence Intervals (CIs). The articles were evaluated for quality and risk of bias using the Newcastle-Ottawa Scale and QUIPS tool, respectively. The meta-analysis was conducted with random-effects model according to the Hartung-Knapp-Sidik-Jonkman method and results were depicted in classical Forest plots. Studies heterogeneity was determined by I² and Tau² statistics. The relationship between p53 mutation and clinic-pathological variables was examined using the χ² test.

RESULTS

Nine articles met the eligibility criteria and went to the final analysis. Sample size ranged from 51 to 1043 patients. All studies were retrospective. The Newcastle Ottawa Scale score was >6 in all studies, QUIPS risk of bias was low in 6, moderate in 3 studies. Only three studies analysed the entire p53 gene coding region. The DNA sequencing technological platforms varied from Sanger to NGS sequencing techniques. The p53 mutational frequencies ranged from 35.0 to 73.0%. A strong association (p<0.0001) emerged between p53 alteration and left-sided CRC. The final pooled HR (p53 mutated vs p53 wild-type tumours) for overall survival was 1.30 (95% CI: 0.75-2.25) at random-effects model.

CONCLUSIONS

The available evidence does not support a prognostic role for p53 in metastatic CRC patients. Prospective studies, with larger sample sizes and consistent and harmonized methodology, are needed to explore the prognostic role of p53 in metastatic CRC patients.

Association of β-Catenin, APC, SMAD3/4, Tp53, and Cyclin D1 Genes in Colorectal Cancer: A Systematic Review and Meta-Analysis

Objectives

Accumulating evidence indicates that the expression and/or variants of several genes play an essential role in the progress of colorectal cancer (CRC). The current study is a meta-analysis undertaken to estimate the prognosis and survival associated with CTNNB1/β-catenin, APC, Wnt, SMAD3/4, TP53, and Cyclin D1 genes among CRC patients.

Methods

The authors searched PubMed, EMBASE, and Science Direct for relevant reports published between 2000 and 2020 and analyzed them to determine any relationship between the (immunohistochemically/sequencing-detected) gene expression and variants of the selected genes and the survival of CRC patients.

Results

The analysis included 34,074 patients from 64 studies. To evaluate association, hazard ratios (HRs) were estimated for overall survival (OS) or disease-free survival (DFS), with a 95% confidence interval (CIs). Pooled results showed that β-catenin overexpression, APC mutation, SMAD-3 or 4 loss of expression, TP53 mutations, and Cyclin D1 expression were associated with shorter OS. β-Catenin overexpression (HR: 0.137 (95% CI: 0.131–0.406)), loss of expression of SMAD3 or 4 (HR: 0.449 (95% CI: 0.146–0.753)), the mutations of TP53 (HR: 0.179 (95% CI: 0.126–0.485)), and Cyclin D1 expression (HR: 0.485 (95% CI: 0.772–0.198)) also presented risk for shorter DFS.

Conclusions

The present meta-analysis indicates that overexpression or underexpression and variants of CTNNB1/β-catenin, APC, SMAD3/4, TP53, and Cyclin D1 genes potentially acted as unfavorable biomarkers for the prognosis of CRC. The Wnt gene was not associated with prognosis.

The Role of p53 Dysfunction in Colorectal Cancer and Its Implication for Therapy

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide. The carcinogenesis of CRC is based on a stepwise accumulation of mutations, leading either to an activation of oncogenes or a deactivation of suppressor genes. The loss of genetic stability triggers activation of proto-oncogenes (e.g., KRAS) and inactivation of tumor suppression genes, namely TP53 and APC, which together drive the transition from adenoma to adenocarcinoma. On the one hand, p53 mutations confer resistance to classical chemotherapy but, on the other hand, they open the door for immunotherapy, as p53-mutated tumors are rich in neoantigens. Aberrant function of the TP53 gene product, p53, also affects stromal and non-stromal cells in the tumor microenvironment. Cancer-associated fibroblasts together with other immunosuppressive cells become valuable assets for the tumor by p53-mediated tumor signaling. In this review, we address the manifold implications of p53 mutations in CRC regarding therapy, treatment response and personalized medicine.

Cellular Mechanisms Accounting for the Refractoriness of Colorectal Carcinoma to Pharmacological Treatment

Simple Summary

Colorectal cancer (CRC) causes a high number (more than 800,000) of deaths worldwide each year. Better methods for early diagnosis and the development of strategies to enhance the efficacy of the therapeutic approaches used to complement or substitute surgical removal of the tumor are urgently needed. Currently available pharmacological armamentarium provides very moderate benefits to patients due to the high resistance of tumor cells to respond to anticancer drugs. The present review summarizes and classifies into seven groups the cellular and molecular mechanisms of chemoresistance (MOC) accounting for the failure of CRC response to the pharmacological treatment.

Abstract

The unsatisfactory response of colorectal cancer (CRC) to pharmacological treatment contributes to the substantial global health burden caused by this disease. Over the last few decades, CRC has become the cause of more than 800,000 deaths per year. The reason is a combination of two factors: (i) the late cancer detection, which is being partially solved by the implementation of mass screening of adults over age 50, permitting earlier diagnosis and treatment; (ii) the inadequate response of advanced unresectable tumors (i.e., stages III and IV) to pharmacological therapy. The latter is due to the existence of complex mechanisms of chemoresistance (MOCs) that interact and synergize with each other, rendering CRC cells strongly refractory to the available pharmacological regimens based on conventional chemotherapy, such as pyrimidine analogs (5-fluorouracil, capecitabine, trifluridine, and tipiracil), oxaliplatin, and irinotecan, as well as drugs targeted toward tyrosine kinase receptors (regorafenib, aflibercept, bevacizumab, cetuximab, panitumumab, and ramucirumab), and, more recently, immune checkpoint inhibitors (nivolumab, ipilimumab, and pembrolizumab). In the present review, we have inventoried the genes involved in the lack of CRC response to pharmacological treatment, classifying them into seven groups (from MOC-1 to MOC-7) according to functional criteria to identify cancer cell weaknesses. This classification will be useful to pave the way for developing sensitizing tools consisting of (i) new agents to be co-administered with the active drug; (ii) pharmacological approaches, such as drug encapsulation (e.g., into labeled liposomes or exosomes); (iii) gene therapy interventions aimed at restoring the impaired function of some proteins (e.g., uptake transporters and tumor suppressors) or abolishing that of others (such as export pumps and oncogenes).

Effect of Coexisting KRAS and TP53 Mutations in Patients Treated With Chemotherapy for Non-small-cell Lung Cancer

BACKGROUND

KRAS and TP53 are common mutations in non-small-cell lung cancer (NSCLC). The Lung Adjuvant Cisplatin Evaluation Biological Program group found adjuvant chemotherapy to be deleterious in patients with coexisting KRAS/TP53 mutations.

PATIENTS AND METHODS

To validate these results, patients with NSCLC tested for KRAS and TP53 mutations and receiving chemotherapy for any stage NSCLC were selected. Mutation status was analyzed using next generation sequencing (Illumina) or multiplex recurrent mutation detection (MassARRAY, Agena Biosciences) assays, and was correlated with clinical and demographic data. Disease-free (DFS) or progression-free survival (PFS) was the main endpoint, and overall survival (OS) was the secondary endpoint.

RESULTS

Among 218 patients, 28 had coexisting KRAS/TP53 mutations, 77 TP53, 37 KRAS, 76 had neither KRAS nor TP53 mutation (WT/WT). There was no DFS/PFS difference for the KRAS/TP53 group versus all others among 99 patients who received adjuvant chemotherapy (hazard ratio [HR], 1.22; 95% confidence interval [CI], 0.61-2.44; P = .57), 27 stage III patients who received chemo-radiation (HR, 0.87; 95% CI, 0.32-2.38; P = .8), and 63 patients who received palliative chemotherapy (HR, 0.68; 95% CI, 0.31-1.48; P = .33). OS was longer in the WT/WT group compared with any other group (KRAS: HR, 1.87; 95% CI, 1.02-3.43; P = .043; TP53: HR, 2.17; 95% CI, 1.3-3.61; P = .0028; KRAS/TP53: HR, 2.06; 95% CI, 1.09-3.88; P = .026). No OS difference was seen for KRAS/TP53 compared with the other groups (HR, 1.26; 95% CI, 0.75-2.13; P = .38).

CONCLUSIONS

There was no significant difference in DFS/PFS between the 4 groups. However, OS was longer for patients with TP53 and KRAS wild-type NSCLC who received chemotherapy for any stage compared with patients with KRAS, TP53 mutation, or double mutant tumors.

Improved potency of F10 relative to 5-fluorouracil in colorectal cancer cells with p53 mutations

Aim:

Resistance to fluoropyrimidine drugs (FPs) is a major cause of mortality in colorectal cancer (CRC). We assessed the potency advantage of the polymeric FP F10 relative to 5-fluorouracil (5FU) in four human CRC cell lines that differ only in TP53 mutational status to determine how p53 mutations affect drug response and whether F10 is likely to improve outcomes.

Methods:

HCT-116 human CRC cells (p53^+/+) and three isogenic variants (p53^−/−, R248W/+, R248W/−) were assessed for drug response. Resistance factors were derived from cell viability data and used to establish the relative potency advantage for F10. Rescue studies with exogenous uridine/thymidine determined if cytotoxicity resulted from DNA-directed processes.

Results:

Significant resistance to 5-FU resulted from p53-loss or from gain-of-function (GOF) mutation (R248W) and was greatest when GOF mutation was coupled with loss of wild-type p53. F10 is much more potent than 5-FU (137–314-fold depending on TP53 mutational status). F10 and 5-FU induce apoptosis by DNA- and RNA-directed mechanisms, respectively, and only F10 shows a modest enhancement in cytotoxicity upon co-treatment with leucovorin.

Conclusion:

TP53 mutational status affects inherent sensitivity to FPs, with p53 GOF mutations most deleterious. F10 is much more effective than 5-FU regardless of TP53 mutations and has potential to be effective to CRC that is resistant to 5-FU due, in part, to TP53 mutations.6,7