Heterogeneous clinical and pathological landscapes of HER2 positive colorectal cancer

Introduction: Metastatic (m) colorectal cancer (CRC) can be divided into specific subgroups under the 'one gene, one drug' paradigm of precision medicine. Progress of targeted therapy in mCRC patients significantly improved the overall survival rate, notably by therapy targeting of EGFR signaling in RAS wild-type mCRC patients. Activation of the HER2 pathway is an important mechanism of resistance for anti-EGFR therapy.Area covered: Inhibition of HER2 with monoclonal antibodies and/or tyrosine kinase inhibitors induces tumor responses in partial HER2-positive CRC refractory to standard systemic therapy. This manuscript aimed to provide an overall insight of the HER2 expression pattern and highlighted specific clinicopathological and molecular features involved in mCRC. In addition, we summarize preclinical and clinical trials in HER2-positive mCRC.Expert opinion: The status and progression of HER2-positive gastric cancer and breast cancer and anti-HER2 therapy have been reported widely. However, the understanding of HER2-positive CRC models which may guide future therapeutic decision-making is poor. Therefore, it is essential to summarize the existing research to extract similarity and difference among various studies.

Landscape of Current Targeted Therapies for Advanced Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent and lethal cancer types worldwide. While surgery with chemotherapy and radiotherapy remains the only curative approach for localized CRC, for metastatic disease the therapeutic landscape has significantly evolved over the last years. Development and approval of novel targeted therapies, such as monoclonal antibodies against EGFR and VEGF, have significantly increased the median survival of patients with metastatic disease, with some trials reporting a benefit over 40 months. Increasing accessibility of high throughput sequencing has unraveled several new therapeutic targets. Actionable alterations, such as HER2 overexpression, BRAF mutations, and NTRK fusions, are currently available in metastatic disease, providing significant therapeutic opportunities for these patients, while new emerging agents, as immune checkpoint inhibitors, promise better treatment options in the near future. In this chapter, an overview of established and future CRC targeted therapies in the clinical setting is provided, as well as their mechanism of action, limitations, and future applicability.

Relative Risk of Peripheral Neuropathy With Ado-Trastuzumab Emtansine (T-DM1) Compared to Taxane-Based Regimens in Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Cancers: A Systematic Review and Meta-Analysis

Background

Peripheral neuropathy (PN), especially peripheral sensory neuropathy (PSN), is significant toxicity of taxanes, the most used class of microtubule inhibitors for human epidermal growth factor receptor 2 (HER2)-positive breast cancer patients. Ado-trastuzumab emtansine (T-DM1) is a HER2-targeted antibody-drug conjugate, consisting of trastuzumab and a microtubule inhibitor DM1, which has been approved for HER2-positive breast cancer. T-DM1 has also been found to cause significant PN, including PSN.

Methods

We conducted a systematic review and meta-analysis of phase 3 randomized controlled trials using T-DM1 in the experimental arm and a taxane-based regimen in the control arm to determine the relative risk of PN and PSN associated with T-DM1 as compared to taxanes. A total of 1,857 patients were included in the analysis. The Cochran-Mantel-Haenszel method and the random-effects model were used to calculate the pooled risk ratio (RR) with a 95% confidence interval (CI) for all-grade and grade ≥3 PN and PSN. 

Results

The relative risks of all-grade PN and all-grade PSN were lower with T-DM1 compared to taxanes. The pooled RR of all-grade PN was 0.59, 95% CI: 0.39-0.89, P = 0.01, and the pooled RR of all-grade PSN was 0.58, 95% CI: 0.46-0.74, P < 0.0001.

Conclusions

Our meta-analysis demonstrated that T-DM1 is associated with a relatively lower risk of all-grade PN and PSN than the taxane-based regimens for HER2-positive cancers. It could be an area of consideration in selecting therapy for HER2-positive breast cancer patients at high risk of developing or having pre-existing PN and PSN.

Role of Her-2 in Gastrointestinal Tumours beyond Gastric Cancer: A Tool for Precision Medicine

Gastrointestinal (GI) tumors account for a quarter of all the cancer burden and a third of the global cancer-related mortality. Among them, some cancers retain a dismal prognosis; therefore, newer and innovative therapies are urgently needed in priority disease areas of high-unmet medical need. In this context, HER2 could be a relevant prognostic and predictive biomarker acting as a target for specific drugs. However, if the role of HER2 has been object of investigation for several years in gastric cancer, it is not well established in other GI malignancies. The aim of this narrative review was to portray the current landscape of the potential role of HER2 as a predictive biomarker for GI tumors beyond gastric cancer. In colon cancer, the benefit from anti-HER2 therapies is less clear than in gastric neoplasms for the lack of controlled studies. Pancreatic, biliary tract adenocarcinomas and hepatocarcinoma may derive a less clear clinical benefit by using anti-HER2 agents in HER2 positive tumors. Overall, the results are promising and seem to suggest that the integration of multiple modalities of therapies can optimize the cancer care. However, further prospective trials are needed to validate the use of personalized targeted therapies in this field.

Treatments after first progression in metastatic colorectal cancer. A literature review and evidence-based algorithm

Prolonging survival, achieving symptoms palliation and preserving quality of life are the primary therapeutic goals of treatments administered after disease progression in mCRC. Even if the impact of these therapies on the prognosis of affected patients is less relevant than the impact of the upfront treatment, tailoring the optimal second-line therapy is increasingly important. Several therapeutic options are available, and different factors including not only patient- and disease-related characteristics, but also the first-line treatment received (i.e., type, timing of disease progression, observed outcome and reported toxicities) may drive this choice. Herein, we describe the current state of the art in the landscape of treatments after progression in mCRC. Based on a critical review of the literature, we built a patient-oriented therapeutic algorithm, aiming to guide clinicians in their daily decision-making.

Precision Approaches in the Management of Colorectal Cancer: Current Evidence and Latest Advancements Towards Individualizing the Treatment

The genetic and molecular underpinnings of metastatic colorectal cancer have been studied for decades, and the applicability of these findings in clinical decision making continues to evolve. Advancements in translating molecular studies have provided a basis for tailoring chemotherapeutic regimens in metastatic colorectal cancer (mCRC) treatment, which have informed multiple practice guidelines. Various genetic and molecular pathways have been identified as clinically significant in the pathogenesis of metastatic colorectal cancer. These include rat sarcoma (RAS), epithelial growth factor receptor (EGFR), vascular endothelial growth factor VEGF, microsatellite instability, mismatch repair, and v-raf murine sarcoma viral oncogene homolog b1 (BRAF) with established clinical implications. RAS mutations and deficiencies in the mismatch repair pathway guide decisions regarding the administration of anti-EGFR-based therapies and immunotherapy, respectively. Furthermore, there are several emerging pathways and therapeutic modalities that have not entered mainstream use in mCRC treatment and are ripe for further investigation. The well-established data in the arena of targeted therapies provide evidence-based support for the use or avoidance of various therapeutic regimens in mCRC treatment, while the emerging pathways and platforms offer a glimpse into the future of transforming a precision approach into a personalized treatment.

Prognostic Value and Molecular Landscape of HER2 Low-Expressing Metastatic Colorectal Cancer

BACKGROUND

The prognostic value and molecular landscape of human epidermal growth factor receptor 2 (HER2) low-expressing (HER2-L) metastatic colorectal cancer (mCRC) remain unclear.

PATIENTS AND METHODS

This study enrolled patients with mCRC who had undergone surgical resection of primary tumor. Using the specimen, we evaluated HER2 expression by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). HER2 positivity was defined as follows: HER2 positivity (HER2-Pos) as IHC 3 + or IHC 2+/FISH positive, HER2-L as IHC 2+/FISH negative or IHC 1+, and HER2 negativity (HER2-Neg) as IHC 0+. Gene alterations were determined by next-generation sequencing.

RESULTS

Between 2005 and 2015, a total of 370 patients were analyzed, comprising 15 patients (4%) with HER2-Pos, 21 (6%) with HER2-L, and 334 (90%) with HER2-Neg disease. The clinicopathologic characteristics among groups had no differences. HER2-L had a significantly higher proportion of coaltered RAS mutation than HER2-Pos (P = .037). With a median follow-up of 101.8 months, HER2-L had a significantly better median overall survival than HER2-Pos (P = .029) (18.2 months in HER2-Pos vs. 33.3 in HER2-L vs. 27.9 in HER2-Neg). In 58 patients harboring wild-type RAS and receiving anti-EGFR antibody therapy, HER2-L had a better median progression-free survival tendency than HER2-Pos, with 2.2 months in HER2-Pos, 7.8 in HER2-L, and 5.1 in HER2-Neg (P = .036).

CONCLUSION

HER2-L mCRC showed a better prognosis than HER2-Pos mCRC, and it is similar to HER2-Neg mCRC. Hence, HER2-L mCRC might have different biologic behavior in terms of prognostic value and molecular landscape of mCRC, suggesting the possibility of implementation of HER2-guided clinical development against HER2-expressing mCRC.

Up-and-Coming Experimental Drug Options for Metastatic Colorectal Cancer

Colorectal cancer is one of the top causes of cancer and cancer-related deaths worldwide. The prognosis of metastatic colorectal cancer is poor and treatment options are limited. Many patients will run out of treatment options before they become medically unfit for therapy. As such, there is a need to expand upon the current understanding of disease biology as well as drug resistance mechanisms in order to create new approaches for therapy. In this review article, we will discuss the mechanistic rationale and clinical data for new drugs and therapeutic combinations under development for metastatic colorectal cancer.

Impact of inter-reader contouring variability on textural radiomics of colorectal liver metastases

BACKGROUND

Radiomics is expected to improve the management of metastatic colorectal cancer (CRC). We aimed at evaluating the impact of liver lesion contouring as a source of variability on radiomic features (RFs).

METHODS

After Ethics Committee approval, 70 liver metastases in 17 CRC patients were segmented on contrast-enhanced computed tomography scans by two residents and checked by experienced radiologists. RFs from grey level co-occurrence and run length matrices were extracted from three-dimensional (3D) regions of interest (ROIs) and the largest two-dimensional (2D) ROIs. Inter-reader variability was evaluated with Dice coefficient and Hausdorff distance, whilst its impact on RFs was assessed using mean relative change (MRC) and intraclass correlation coefficient (ICC). For the main lesion of each patient, one reader also segmented a circular ROI on the same image used for the 2D ROI.

RESULTS

The best inter-reader contouring agreement was observed for 2D ROIs according to both Dice coefficient (median 0.85, interquartile range 0.78-0.89) and Hausdorff distance (0.21 mm, 0.14-0.31 mm). Comparing RF values, MRC ranged 0-752% for 2D and 0-1567% for 3D. For 24/32 RFs (75%), MRC was lower for 2D than for 3D. An ICC > 0.90 was observed for more RFs for 2D (53%) than for 3D (34%). Only 2/32 RFs (6%) showed a variability between 2D and circular ROIs higher than inter-reader variability.

CONCLUSIONS

A 2D contouring approach may help mitigate overall inter-reader variability, albeit stable RFs can be extracted from both 3D and 2D segmentations of CRC liver metastases.

Molecular Targets for the Treatment of Metastatic Colorectal Cancer

Over the past years, colorectal cancer (CRC) was subtyped according to its molecular and genetic characteristics, allowing the development of therapeutic strategies, based on predictive biomarkers. Biomarkers such as microsatellite instability (MSI), RAS and BRAF mutations, HER2 amplification or NTRK fusions represent major tools for personalized therapeutic strategies. Moreover, the routine implementation of molecular predictive tests provides new perspectives and challenges for the therapeutic management of CRC patients, such as liquid biopsies and the reintroduction of anti-EGFR monoclonal antibodies. In this review, we summarize the current landscape of targeted therapies for metastatic CRC patients, with a focus on new developments for EGFR blockade and emerging biomarkers (MSI, HER2, NTRK).

Refractory Metastatic Colorectal Cancer: Current Challenges and Future Prospects

Despite advances, patients with metastatic colorectal cancer (mCRC) still have poor long-term survival. Identification of molecular subtypes is important to guide therapy through standard treatment pathways and holds promise for the development of new treatments. Following standard first- and second-line chemotherapy plus targeted agents, many patients retain a reasonable performance status, and thus are seeking further effective treatment to extend life and maintain symptom control. The challenge lies in selecting the most appropriate therapy in the third- and fourth-line settings, from a range of options including the relatively new oral agents TAS-102 and regorafenib, or rechallenge with previous chemotherapy or anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies (mAB). Beyond this, therapy consists of trials involving novel agents and new combinations of treatments with theoretical synergy and/or non-overlapping toxicity. There is a great focus on enhancing immunogenicity in mCRC, to reflect the impressive results of immunotherapy drugs in the small cohort with mismatch repair deficient (dMMR) mCRC. Rare molecular subtypes of mCRC are increasingly being identified, including Her2-positive disease, NTRK fusions and others. Clinical trials exploring the efficacy of immunomodulatory and precision agents are plentiful and will hopefully yield clinically meaningful results that can be rapidly translated into routine care.

HER2 in Colorectal Carcinoma: Are We There yet?

HER2 (ERBB2) is a member of the ERBB family of receptor tyrosine kinases and functions to drive signaling in the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. Overall, approximately 2-3% of CRCs exhibit ERBB2 amplification. Multiple phase II clinical trials have now shown that ERBB2 amplification can be predictive of response to anti-ERBB2 targeted therapy. Consequently, recently released guidelines from the National Comprehensive Cancer Network recommend treatment with anti-ERBB2 targeted therapy for RAS wild-type, ERBB2-amplified metastatic CRC. While circumspection is still needed, ERBB2 amplification has now emerged as the next standard-of-care biomarker for metastatic CRC, expanding targeted therapy options for these patients.

Molecular-Biology-Driven Treatment for Metastatic Colorectal Cancer

BACKGROUND

Metastatic CRC (mCRC) is a molecular heterogeneous disease. The aim of this review is to give an overview of molecular-driven treatment of mCRC patients.

METHODS

A review of clinical trials, retrospective studies and case reports was performed regarding molecular biomarkers with therapeutic implications.

RESULTS

RAS wild-type status was confirmed as being crucial for anti-epidermal growth factor receptor (EGFR) monoclonal antibodies and for rechallenge strategy. Antiangiogenic therapies improve survival in first- and second-line settings, irrespective of RAS status, while tyrosine kinase inhibitors (TKIs) remain promising in refractory mCRC. Promising results emerged from anti-HER2 drugs trials in HER2-positive mCRC. Target inhibitors were successful for BRAFV600E mutant mCRC patients, while immunotherapy was successful for microsatellite instability-high/defective mismatch repair (MSI-H/dMMR) or DNA polymerase epsilon catalytic subunit (POLE-1) mutant patients. Data are still lacking on NTRK, RET, MGMT, and TGF-β, which require further research.

CONCLUSION

Several molecular biomarkers have been identified for the tailored treatment of mCRC patients and multiple efforts are currently ongoing to increase the therapeutic options. In the era of precision medicine, molecular-biology-driven treatment is the key to impro patient selection and patient outcomes. Further research and large phase III trials are required to ameliorate the therapeutic management of these patients.

Application of trastuzumab emtansine in HER-2-positive and KRAS/BRAF-mutated colon cancer cells

BACKGROUND

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC) for the treatment of human epidermal growth factor receptor 2 (HER-2)-positive breast cancer. T-DM1 is based on the trastuzumab antibody and delivers a toxic agent into breast cancer cells through endocytic mechanism. This study evaluated whether T-DM1 can be used in HER-2-positive colon cancer cells which harbour KRAS/ BRAF mutation with limited treatment.

MATERIALS AND METHODS

LS174T and HT-29 which are KRAS and BRAF mutant HER-2-positive colon cancer cells were used in this study. Cells were first treated with T-DM1; cetuximab and trastuzumab were applied for comparison, the effect of drug sensitivity was determined. Cells were then transfected with plasmid to overexpress HER-2 or the endocytic protein, caveolin-1 or furthermore pretreated with metformin to examine the effect of T-DM1 efficacy. Finally, a xenograft mouse model was used to evaluate the drug efficacy in vivo.

RESULTS

The results showed that T-DM1 had better inhibitory effect than cetuximab and trastuzumab on LS174T and HT-29 cells. HER-2 or caveolin-1 overexpression with plasmid in the cells to increase T-DM1 recognition or internalization can increase the sensitivity to T-DM1. When cells were pretreated with metformin, caveolin-1 expression was induced and promoted T-DM1 uptake and enhanced cell toxicity. In xenograft mouse model, combined treatment of T-DM1 and metformin had apparent inhibitory effect on subcutaneous tumour growth.

CONCLUSION

The results of this study suggested that T-DM1 has potential in the treatment of HER-2-positive colon cancer cells, and application of metformin has therapeutic benefits during T-DM1 treatment.

Current challenges in the implementation of precision oncology for the management of metastatic colorectal cancer

Over the last few decades, molecularly targeted agents have been used for the treatment of metastatic colorectal cancer. They have made remarkable contributions to prolonging the lives of patients. The emergence of several biomarkers and their introduction to the clinic have also aided in guiding such treatment. Recently, next-generation sequencing (NGS) has enabled clinicians to identify these biomarkers more easily and reliably. However, there is considerable uncertainty in interpreting and implementing the vast amount of information from NGS. The clinical relevance of biomarkers other than NGS are also subjects of debate. This review covers controversial issues and recent findings on such therapeutics and their molecular targets, including VEGF, EGFR, BRAF, HER2, RAS, actionable fusions, Wnt pathway and microsatellite instability for comprehensive understanding of obstacles on the road to precision oncology in metastatic colorectal cancer.