DEPDC1B promotes colorectal cancer via facilitating cell proliferation and migration while inhibiting apoptosis

Colorectal cancer (CRC) is a common malignant tumor with strong invasiveness. Given the reported involvement of DEP domain-containing protein 1B (DEPDC1B) in the progression of some cancers, its role in CRC was explored in this study. DEPDC1B expression in CRC was assessed based on database and tissue microarray (TMA). In addition, the knockdown and overexpression of DEPDC1B in CRC cell lines were constructed using small hairpin RNA (shRNA) interference. The biological function of DEPDC1B in CRC was evaluated in vitro and in vivo through loss/gain-of-function assays. The results demonstrated that DEPDC1B was highly expressed in CRC. Furthermore, DEPDC1B had the ability to promote CRC proliferation and migration coupled by cell apoptosis. In vivo results showed that DEPDC1B knockdown significantly inhibited the growth of xenograft tumors. Additionally, the results of antibody array indicated increased apoptosis-promoting proteins and decreased apoptosis-inhibiting proteins in DEPDC1B-knockdown CRC cells. In conclusion, DEPDC1B played a key driver role in CRC progression, and inhibition of its expression may be a potential target for precision medicine in CRC.

Current therapy of advanced colorectal cancer according to RAS/RAF mutational status

Colorectal cancer is a clinically and molecularly heterogeneous disease. Currently, extended RAS and BRAF mutation testing is obligatory in routine clinical practice before starting any treatment in the metastatic setting. Treatment decision making also includes assessment of the clinical condition of the patient, definition of the treatment goal, and consideration of the primary tumor site. Biological treatment is part of the first-line drug combination unless contraindicated. Mutational status is significantly associated with the outcome of patients and is strongly predictive for anti-EGFR-targeted therapy. The prognosis of RAS mutant CRC is clearly inferior to wild-type cases. RAS remains an elusive target, and specific treatment options are not yet available. Recently, promising results of a direct KRAS G12C inhibitor have been reported; however, further confirmation is needed. The biomarker landscape in mCRC is evolving; new promising markers are awaited with the chance of more precise targeted treatment.

Exploring the best treatment options for BRAF-mutant metastatic colon cancer

The BRAFV600E mutation is a well-accepted poor prognostic factor in patients with metastatic colorectal cancer (mCRC), as it confers Ras-independent stimulation of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway involved in proliferation, migration, angiogenesis and the suppression of apoptosis. Analysis of the potential predictive value of BRAF for treatment efficacy is inherently confounded by this known prognostic impact. Currently, approved therapeutic strategies for patients with BRAF-mutant (BRAF-mt) mCRC are suboptimal, and uncertainty exists regarding how to best treat these patients. Based on the available evidence, it is currently not possible to confirm the superiority of any available treatment options cited in European Society for Medical Oncology and National Comprehensive Cancer Network guidelines (that is, doublet or triplet chemotherapy regimens plus anti-vascular endothelial growth factor or anti-epidermal growth factor receptors), even if triplet chemotherapy plus bevacizumab is the most accepted standard regimen. In this review, we highlight still-emerging strategies that could be deployed to combat BRAF-mt mCRC, including triplet chemotherapy plus available biologic agents, rationally derived combinations of targeted agents and immunotherapy. While it is clear that the needs of patients with BRAF-mt mCRC are currently unmet, we are cautiously optimistic that the recently renewed research interest in these patients will yield clinically relevant insights and therapeutic strategies.

Choosing the right strategy based on individualized treatment effect predictions: combination versus sequential chemotherapy in patients with metastatic colorectal cancer

BACKGROUND

Translating results from randomized trials to individual patients is challenging, since treatment effects may vary due to heterogeneous prognostic characteristics. We aimed to demonstrate model development for individualized treatment effect predictions in cancer patients. We used data from two randomized trials that investigated sequential versus combination chemotherapy in unresectable metastatic colorectal cancer (mCRC) patients.

MATERIAL AND METHODS

We used data from 803 patients included in CAIRO for prediction model development and internal validation, and data from 1423 patients included in FOCUS for external validation. A Weibull model with pre-specified patient and tumour characteristics was developed for a prediction of gain in median overall survival (OS) by upfront combination versus sequential chemotherapy. Decision curve analysis with net benefit was used. A nomogram was built using logistic regression for estimating the probability of receiving second-line treatment after the first-line monochemotherapy.

RESULTS

Median-predicted gain in OS for the combination versus sequential chemotherapy was 2.3 months (IQR: -1.1 to 3.7 months). A predicted gain in favour of sequential chemotherapy was found in 231 patients (29%) and a predicted gain of >3 months for combination chemotherapy in 294 patients (37%). Patients with benefit from sequential chemotherapy had metachronous metastatic disease and a left-sided primary tumour. Decision curve analyses showed improvement in a net benefit for treating all patients according to prediction-based treatment compared to treating all patients with combination chemotherapy. Multiple characteristics were identified as prognostic variables which identify patients at risk of never receiving second-line treatment if treated with initial monochemotherapy. External validation showed good calibration with moderate discrimination in both models (C-index 0.66 and 0.65, respectively).

CONCLUSIONS

We successfully developed individualized prediction models including prognostic characteristics derived from randomized trials to estimate treatment effects in mCRC patients. In times where the heterogeneity of CRC becomes increasingly evident, such tools are an important step towards personalized treatment.

BRAF-Mutated Colorectal Cancer: What Is the Optimal Strategy for Treatment?

OPINION STATEMENT

The BRAF activating mutation, harbored by approximately 10% of colorectal cancers (CRC), confers dramatic prognosis to advanced diseases. In early-stage setting, the identification of the BRAF mutation does not impact the therapeutic decision. Yet, the BRAF mutation could be considered as a stratification factor in adjuvant trials, because of its prognostic impact after relapse. Moreover, both BRAF mutation and mismatch repair (MMR) statuses should be determined in all CRC to help identify sporadic tumors versus Lynch syndrome-related tumors. Indeed, in patients with MMR-deficient (dMMR) tumors and MLH1 loss of expression, the BRAFV600E mutation indicates a sporadic origin. In advanced BRAF-mutated CRC, the standard of care remains fluoropyrimidine-based cytotoxic regimen in combination with bevacizumab. Although a recent meta-analysis showed that there was insufficient data to justify the exclusion of anti-EGFR monoclonal antibodies, antiangiogenic agents should be preferred in the first-line setting. Despite the lack of a randomized phase 3 study dedicated to BRAF-mutated CRC, chemotherapy intensification combining a quadruple association of 5-fluorouracil, oxaliplatin, irinotecan (FOLFOXIRI), and bevacizumab seems like a valid option. Although first results with BRAF inhibitors as single agents in BRAF-mutated CRC were disappointing, their association with therapies targeting the MAPK pathway seems to overcome the primary resistance to BRAF inhibition. In the field of sporadic CRC, the BRAF mutation is strongly associated with MMR deficiency. Considering breakthrough results of immune checkpoint inhibitors in dMMR repair tumors, determination of the MMR status appears to be mandatory. Given the dramatic prognosis conferred by the BRAF mutation, patients with BRAF-mutated advanced CRC need to be systematically identified and proposed for clinical trial enrolment in order to benefit from innovative therapies.

New Therapeutic Opportunities Based on DNA Mismatch Repair and BRAF Status in Metastatic Colorectal Cancer

Recently, colorectal cancer (CRC) subtyping consortium identified four consensus molecular subtypes (CMS1-4). CMS1 is enriched for deficient mismatch repair (dMMR) and BRAF (V600E) tumors. Intriguingly, this subtype has better relapse-free survival but worse overall survival after relapse compared with the other subtypes. Growing evidence is accumulating on the benefit of specific therapeutic strategies such as immune checkpoint inhibition therapy in dMMR tumors and mitogen-activated protein kinase (MAPK) pathway targeted therapy in tumors harboring BRAF (V600E) mutation. After reviewing dMMR prognostic value, immune checkpoints as major targets for dMMR carcinomas will be highlighted. Following, BRAF (V600E) prognostic impact will be reviewed and therapeutic strategies with the combination of cytotoxic agents and especially the combinations of BRAF and MAPK inhibitors will be discussed.

Outcome according to KRAS-, NRAS- and BRAF-mutation as well as KRAS mutation variants: pooled analysis of five randomized trials in metastatic colorectal cancer by the AIO colorectal cancer study group

In this pooled analysis of metastatic colorectal cancer patients, mutations in KRAS, and BRAF were associated with inferior progression-free and overall survival compared with patients with non-mutated tumors. KRAS exon 2 mutation variants were associated with heterogeneous outcome compared with unmutated tumors with KRAS G12C and G13D being associated with rather poor survival.

Background

To explore the impact of KRAS, NRAS and BRAF mutations as well as KRAS mutation variants in patients with metastatic colorectal cancer (mCRC) receiving first-line therapy.

Patients and methods

A total of 1239 patients from five randomized trials (FIRE-1, FIRE-3, AIOKRK0207, AIOKRK0604, RO91) were included into the analysis. Outcome was evaluated by the Kaplan–Meier method, log-rank tests and Cox models.

Results

In 664 tumors, no mutation was detected, 462 tumors were diagnosed with KRAS-, 39 patients with NRAS- and 74 patients with BRAF-mutation. Mutations in KRAS were associated with inferior progression-free survival (PFS) and overall survival (OS) [multivariate hazard ratio (HR) for PFS: 1.20 (1.02–1.42), P = 0.03; multivariate HR for OS: 1.41 (1.17–1.70), P < 0.001]. BRAF mutation was also associated with inferior PFS [multivariate HR: 2.19 (1.59–3.02), P < 0.001] and OS [multivariate HR: 2.99 (2.10–4.25), P < 0.001]. Among specific KRAS mutation variants, the KRAS G12C-variant (n = 28) correlated with inferior OS compared with unmutated tumors [multivariate HR 2.26 (1.25–4.1), P = 0.001]. A similar trend for OS was seen in the KRAS G13D-variant [n = 71, multivariate HR 1.46 (0.96–2.22), P = 0.10]. More frequent KRAS exon 2 variants like G12D [n = 152, multivariate HR 1.17 (0.86–1.6), P = 0.81] and G12V [n = 92, multivariate HR 1.27 (0.87–1.86), P = 0.57] did not have significant impact on OS.

Conclusion

Mutations in KRAS and BRAF were associated with inferior PFS and OS of mCRC patients compared with patients with non-mutated tumors. KRAS exon 2 mutation variants were associated with heterogeneous outcome compared with unmutated tumors with KRAS G12C and G13D (trend) being associated with rather poor survival.

Effect of RAS status on anti-EGFR monoclonal antibodies + 5-FU infusion-based chemotherapy in first-line treatment of metastatic colorectal cancer: A meta-analysis

Purpose

To investigate the effect of RAS on anti-EGFR moAb + 5-FU infusion based chemotherapy in first-line treatment of mCRC.

Methods

The MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane databases and ClinicalTrials.gov databases were independently reviewed. Primary end points included overall response rate (ORR), progression-free survival (PFS), overall survival (OS) and toxicities. Correlation between RAS status and PFS, OS, ORR or toxicities was expressed as a hazard ratio (HR) or relative risk (RR).

Results

KRAS exon 2 wild-type (-wt) mCRC benefited from adding anti-EGFR moAb (compared with chemotherapy alone: OS: HR 0.88, P = 0.008; PFS: HR 0.74, P < 0.001; ORR: RR 1.34, P = 0.003. Compared with Bevacizumab: OS: HR 0.83, P = 0.003). KRAS exon 2-wt but other RAS mutations mCRC did not benefit from adding anti-EGFR moAb. RAS-wt mCRC benefited from adding anti-EGFR moAb (compared with chemotherapy alone: OS: HR: 0.75, P < 0.001; PFS: HR 0.65, P < 0.001; ORR: RR 1.51, P = 0.020. Compared with Bevacizumab: OS: HR 0.79, P = 0.002). KRAS exon 2-wt but BRAF mutation mCRC did not benefit from adding anti-EGFR moAb. Subgroup analysis suggested that anti-EGFR moAb prolonged PFS for male, liver metastasis-only, ECOG 0–1, and colon primary site groups. Anti-EGFR moAb increased controllable grade 3–4 toxicities including rash, diarrhea, and anemia.

Conclusions

Adding anti-EGFR moAb as first-line treatment in RAS-wt mCRC prolonged OS. Whether BRAF mutation is a predictive marker to anti-EGFR moAb is not clear.