First-line therapy for metastatic colorectal cancer: Current perspectives and future directions

Exploring the Relationship Between KRAS, NRAS, and BRAF Mutations and Clinical Characteristics in Iranian Colorectal Cancer Patients

BACKGROUND

Patients with colorectal cancer can benefit from anti-EGFR (epidermal growth factor receptor) therapy. However, this therapy is not effective for treating colorectal cancers with constitutive activating mutations in the KRAS, NRAS, and BRAF genes. Molecular analysis of tumor tissue frequently informs treatment decisions for colorectal cancer. This study aims to identify KRAS, NRAS, and BRAF mutations in Iranian patients diagnosed with colorectal cancer and to assess the prevalence of these mutations relative to the tumor differentiation stage within these populations.

METHODS

From April 2018 to December 2022, 2000 specimens from patients with colorectal cancer were collected. Data on sex, age, and tumor differentiation stage were recorded for all samples. For mutation detection, the KRAS and NRAS exons (2, 3, and 4) were amplified using the Diatech kit, and a specific primer was used to amplify BRAF exon 15. Pyrosequencing was then performed.

RESULTS

Analysis of samples revealed that 1105 specimens (55.3%) contained mutations in at least one of the screened genes. Among the genes studied, the highest occurrence was the KRAS mutation at 47.4%, followed by NRAS at 5.3% and BRAF at 2.7%. Most KRAS mutations were found in exon 2 (89.7%), with the G12D mutation being the most prevalent at 32% of cases. There was a significant difference in the rate of KRAS mutations in women (52.5%) compared to men (43.5%) (P =  0.02). For NRAS, the majority mutations were observed in exon 3 (76.2%), with the Q61H mutation being the most prevalent at 28.5% of cases. There were no significant associations between the clinicopathological parameters and mutations.

CONCLUSION

The study's findings indicate a rising frequency of mutations in these genes in Iran, highlighting the need to screening mutations in the main exons of all three genes for effective colorectal cancer treatment strategies.

Estrogen treatment in combination with pyruvate kinase M2 inhibition precipitate significant cumulative antitumor effects in colorectal cancer

It is well established that pyruvate kinase M2 (PKM2) activity contributes to metabolic reprogramming in various cancers, including colorectal cancer (CRC). Estrogen or 17β-estradiol (E2) signaling is also known to modulate glycolysis markers in cancer cells. However, whether the inhibition of PKM2 combined with E2 treatment could adversely affect glucose metabolism in CRC cells remains to be investigated. First, we confirmed the metabolic plasticity of CRC cells under varying environmental conditions. Next, we identified glycolysis markers that were upregulated in CRC patients and assessed in vitro mRNA levels following E2 treatment. We found that PKM2 expression, which is highly upregulated in CRC clinical samples, is not altered by E2 treatment in CRC cells. In this study, glucose uptake, generation of reactive oxygen species (ROS), lactate production, cell viability, and apoptosis were evaluated in CRC cells following E2 treatment, PKM2 silencing, or a combination of both. Compared to individual treatments, combination therapy resulted in a significant reduction in cell viability and enhanced apoptosis. Glucose uptake and ROS production were markedly reduced in PKM2-silenced E2-treated cells. The data presented here suggest that E2 signaling combined with PKM2 inhibition cumulatively targets glucose metabolism in a manner that negatively impacts CRC cell growth. These findings hold promise for novel therapeutic strategies targeting altered metabolic pathways in CRC.

IL-6, TNF-α and IL-12p70 levels in patients with colorectal cancer and their predictive value in anti-vascular therapy

We aimed to analyze the levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-12 (IL-12p70) in colorectal cancer and evaluate the predictive significance of clinical efficacy of patients with colorectal cancer treated with anti-vascular therapy combined with chemotherapy. A retrospective study of 162 patients with colorectal cancer in Fujian Medical University Hospital was conducted from January 2019 to December 2020. A comparative analysis of the levels of IL-6, TNF-α and IL-12p70 between the two groups were studied. The relationship between the levels and the clinical characteristics of patients was observed; the factors affecting the levels of IL-6, TNF-α, and IL-12p70 in colorectal cancer patients were analyzed, and the predictive validity of the efficacy of anti-vascular therapy was evaluated. We observed that the individual expression levels of IL-6, TNF-α and IL-12p70 in the patients with colorectal cancer are related to lymph node metastasis, TNM staging, and degree of differentiation (P<0.05); however, they are irrelevant to the age, sex, and tumor location of patients with colorectal cancer (P>0.05). The multiple stepwise regression analysis indicates that lymph node metastasis and TNM staging are independent risk factors that correlate with IL-6 and IL-12p70 levels in colorectal cancer patients (P<0.01). The degree of differentiation was found to be an independent risk factor connected to TNF- α levels of patients with colorectal cancer. The change of IL-12p70 level could predict the validity of anti-vascular treatment for advanced colorectal cancer. When evaluated for combined expression, IL-6 and IL-12p70 in patients with colorectal cancer closely related to lymph node metastasis and TNM staging. IL-12p70 can be used as a predictor of anti-vascular therapy with colorectal cancer.

Mutational landscape of circulating tumor DNA identifies distinct molecular features associated with therapeutic response in patients with metastatic colorectal cancer

Background:

We investigated the mutational landscape of circulating tumor DNA (ctDNA) in predicting tumor response to first-line treatment in patients with metastatic colorectal cancer (mCRC).

Methods:

We included 41 patients with initially unresectable mCRC, treated with 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX)/5-fluorouracil/leucovorin/irinotecan (FOLFIRI) with/without bevacizumab (Bev)/cetuximab (Cet). Blood samples were prospectively collected at two timepoints: at baseline and after four cycles of first-line treatment. Mutational status of 1086 genes were studied in ctDNA by targeted next-generation sequencing (NGS). Molecular mutational burden (MMB) was defined as mean mutation frequency among obtained mutations for each gene. To evaluate the association between molecular characteristics of cfDNA and therapeutic response better, we divided these patients into MMB-high and MMB-low group according to the median value of MMB (0.3).

Results:

Among the 41 enrolled patients, alterations of six genes ( TRIM24, SPEN, RNF43, PRKAR1A, KRAS, and KDM5 C) were found at baseline. Baseline MMB of six genes was significantly lower in partial response (PR)/stable disease (SD) patients than progression disease (PD) patients ( p = 0.0012). Further analysis demonstrated that genomic profiling of ctDNA from pretreatment blood samples was significantly different between PR/SD (non-PD) group and PD group. By comparing the baseline levels of KRAS MMB in the two subgroups, we found that PD cases were all MMB-high, whereas non-PD cases were mainly in MMB-low subgroup. Furthermore, patients with low-KRAS MMB had superior response rate, significantly longer progression-free survival (PFS) and longer overall survival (OS) than high-KRAS MMB group.

Conclusions:

This prospective and serial genomic profiling study revealed the utility of ctDNA in predicting clinical outcomes in mCRC patients under first-line treatment. Levels of KRAS MMB might aid in monitoring therapeutic efficacy in mCRC patients at pretreatment/after four cycles of first-line treatment.

Imaging predictors of BRAF mutation in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of cancer deaths and is associated with various genetic mutations. BRAF mutations, found in approximately 10% of all CRCs, are associated with negative predictive outcomes. The goal of this study was to assess the relationship between the imaging findings and BRAF statuses of CRC patients.

MATERIALS AND METHODS

The study population was colorectal cancer patients who underwent biopsy or surgery in a single institution from September 2004 to October 2018, and in whom the pathologic specimens were tested for BRAF mutation. The exclusion criteria were (1) patients without pre-operative cross-sectional imaging, and (2) patients whose tumors were invisible on imaging. Two hundred and eighty-three patients met the inclusion criteria. Among them, 128 were excluded, and a total of 155 patients were enrolled in the study.

RESULTS

BRAF mutations were significantly more common in female patients (p = 0.007). Patients with mutated BRAF were significantly older than those with wild-type BRAF (p = 0.001). BRAF-mutant tumors were predominant in right-sided colon (p = 0.001) with higher numbers of polypoid- or mass-like morphology (p = 0.019) and heterogeneous enhancement (p = 0.009). Compared to their wild-type counterparts, BRAF-mutated CRCs have a lower occurrence of non-peritoneal, and overall metastases (p = 0.013 and p = 0.004, respectively). Logistic regression analysis showed three significant factors for the prediction of BRAF mutations in CRC patients: right-sided location (p = 0.002), heterogeneous tumor enhancement (p = 0.039), and lack of non-peritoneal metastasis (p = 0.043).

CONCLUSION

By recognizing the specific imaging features of BRAF-mutant CRCs, it would be possible to identify a patient who has a higher risk of carrying BRAF mutation.

Down-Regulation of Cannabinoid Type 1 (CB1) Receptor and its Downstream Signaling Pathways in Metastatic Colorectal Cancer

Changes in the regulation of endocannabinoid production, together with an altered expression of their receptors are hallmarks of cancer, including colorectal cancer (CRC). Although several studies have been conducted to understand the biological role of the CB1 receptor in cancer, little is known about its involvement in the metastatic process of CRC. The aim of this study was to investigate the possible link between CB1 receptor expression and the presence of metastasis in patients with CRC, investigating the main signaling pathways elicited downstream of CB1 receptor in colon cancer. Fifty-nine consecutive patients, with histologically proven colorectal cancer, were enrolled in the study, of which 30 patients with synchronous metastasis, at first diagnosis and 29 without metastasis. A low expression of CB1 receptor were detected in primary tumor tissue of CRC patients with metastasis and consequently, we observed an alteration of CB1 receptor downstream signaling. These signaling routes were also altered in intestinal normal mucosa, suggesting that, normal mucosa surrounding the tumor provides a realistic picture of the molecules involved in tissue malignant transformation. These observations contribute to the idea that drugs able to induce CB1 receptor expression can be helpful in order to set new anticancer therapeutic strategies.