Evolving treatment of advanced colorectal cancer

New Insight to Overcome Tumor Resistance: An Overview from Cellular to Clinical Therapies

Disease relapse caused by drug resistance still represents a major clinical hurdle in cancer treatments. Tumor cells may take advantage of different intracellular and genetic systems attenuating the drug effects. Resistant cells or minimal residual disease (MRD) cells have strong clinical relevance, as they might give rise to secondary tumors when the therapy is concluded. Thus, MRDs are crucial therapeutic targets in order to prevent tumor relapse. Therefore, several groups aim at understanding how MRDs are orginated, characterizing their molecular features, and eradicating them. In this review, we will describe MRD from a genetic, evolutionary, and molecular point of view. Moreover, we will focus on the new in vitro, in vivo, preclinical, and clinical studies that aim at eradicating tumor resistance.

NDRG1 enhances the sensitivity of cetuximab by modulating EGFR trafficking in colorectal cancer

N-myc downstream-regulated gene 1 (NDRG1) is a key regulator that interacts with many classic tumor signaling pathways, including some molecules downstream of the epidermal growth factor receptor (EGFR). However, whether NDRG1 is involved in the mechanism of resistance to cetuximab (CTX), the first monoclonal antibody targeting the EGFR has not been reported. Here, we found that NDRG1 enhanced the sensitivity of CTX in colorectal cancer (CRC) cell lines. Afterwards, we determined the underlying mechanism of this phenomenon. We demonstrated that NDRG1 inhibited the expression of EGFR; blocked EGFR phosphorylation and reduced the EGFR distribution in the cell membrane, cytoplasm and nucleus. And then, NDRG1 suppressed the EGFR downstream signaling: RAS/RAF/ERK and PI3k/AKT/mTOR pathways. Moreover, we discovered that NDRG1 attenuated the endocytosis and degradation of EGFR induced by caveolin-1 (Cav1). Additionally, our findings were further observed in an animal model and human tissues. Our results represent a potentially significant discovery that explains the mechanisms of NDRG1 in CTX resistance. NDRG1 could be a promising biomarker to predict optimum responses to CTX, and a key target to enhance CTX activity in the treatment of metastatic CRC (mCRC).

OncoKB: A Precision Oncology Knowledge Base

PURPOSE

With prospective clinical sequencing of tumors emerging as a mainstay in cancer care, there is an urgent need for a clinical support tool that distills the clinical implications associated with specific mutation events into a standardized and easily interpretable format. To this end, we developed OncoKB, an expert-guided precision oncology knowledge base.

METHODS

OncoKB annotates the biological and oncogenic effect and the prognostic and predictive significance of somatic molecular alterations. Potential treatment implications are stratified by the level of evidence that a specific molecular alteration is predictive of drug response based on US Food and Drug Administration (FDA) labeling, National Comprehensive Cancer Network (NCCN) guidelines, disease-focused expert group recommendations and the scientific literature.

RESULTS

To date, over 3000 unique mutations, fusions, and copy number alterations in 418 cancer-associated genes have been annotated. To test the utility of OncoKB, we annotated all genomic events in 5983 primary tumor samples in 19 cancer types. Forty-one percent of samples harbored at least one potentially actionable alteration, of which 7.5% were predictive of clinical benefit from a standard treatment. OncoKB annotations are available through a public web resource (http://oncokb.org/) and are also incorporated into the cBioPortal for Cancer Genomics to facilitate the interpretation of genomic alterations by physicians and researchers.

CONCLUSION

OncoKB, a comprehensive and curated precision oncology knowledge base, offers oncologists detailed, evidence-based information about individual somatic mutations and structural alterations present in patient tumors with the goal of supporting optimal treatment decisions.

Primary and Acquired Resistance of Colorectal Cancer to Anti-EGFR Monoclonal Antibody Can Be Overcome by Combined Treatment of Regorafenib with Cetuximab

PURPOSE

In colorectal cancer, the activation of the intracellular RAS-RAF and PIK3CA-AKT pathways has been implicated in the resistance to anti-EGFR mAbs. We have investigated the role of regorafenib, an oral multikinase inhibitor, in combination with cetuximab, an anti-EGFR mAb, to overcome anti-EGFR resistance.

EXPERIMENTAL DESIGN

We have tested, in vitro and in vivo, the effects of regorafenib in a panel of human colorectal cancer cell lines with a KRAS mutation (SW480, SW620, HCT116, LOVO, and HCT15) or with a BRAF mutation (HT29), as models of intrinsic resistance to cetuximab treatment, and in two human colorectal cancer cell lines (GEO and SW48) that are cetuximab-sensitive, as well as in their derived cells with acquired resistance to cetuximab (GEO-CR and SW48-CR).

RESULTS

Treatment with regorafenib determined a dose-dependent growth inhibition in all colorectal cancer cell lines. The combined treatment with cetuximab and regorafenib induced synergistic antiproliferative and apoptotic effects in cetuximab-resistant cell lines by blocking MAPK and AKT pathways. Nude mice were injected s.c. with HCT116, HCT15, GEO-CR, and SW48-CR cells. The combined treatment caused significant tumor growth inhibition. Synergistic antitumor activity of regorafenib plus cetuximab was also observed in an orthotopic colorectal cancer model of HCT116 cells. In particular, the combined treatment induced a significant tumor growth inhibition in the primary tumor site (cecum) and completely prevented metastasis formation.

CONCLUSIONS

The combined treatment with cetuximab and regorafenib could be a strategy to overcome resistance to anti-EGFR therapies in metastatic colorectal cancer patients.

Regorafenib in metastatic colorectal cancer

Regorafenib is an oral multikinase inhibitor that blocks the activity of protein kinases involved in the regulation of tumor angiogenesis (VEGFR1, 2, 3; angiopoietin-1 receptor), oncogenesis (stem cell growth factor receptor; RET; BRAF including BRAFV600E), and tumor microenvironment (PDGFR-β and FGFR). Based on data from the Phase III CORRECT study, regorafenib stands as a further option for patient affected by metastatic colorectal cancer who have exhausted previous available therapies. Its multi-targeted effect might explain activity in advanced lines of treatment, when cancer cells have been heavily challenged with previous lines of therapy and potentially developed multiple mechanisms of resistance, but also makes difficult to identify predictive biomarkers. In this article we examine preclinical as well as clinical data of regorafenib in the therapy of metastatic colorectal cancer, challenges for potential markers of efficacy and its role in the treatment algorithm.

Personalizing medicine for metastatic colorectal cancer: Current developments

Metastatic colorectal cancer (mCRC) is still one of the tumor types with the highest incidence and mortality. In 2012, colorectal cancer was the second most prevalence cancer among males (9%) and the third among females (8%). In this disease, early diagnosis is important to improve treatment outcomes. However, at the time of diagnosis, about one quarter of patients already have metastases, and overall survival of these patients at 5-years survival is very low. Because of these poor statistics, the development of new drugs against specific targets, including the pathway of angiogenesis, has witnessed a remarkable increase. So, targets therapies through epidermal growth factor and its receptor and also KRAS pathways modulation acquired a main role whether in association with standard chemotherapy and radiotherapy. With the current knowledge in the field of molecular biology, including genetic mutations and polymorphisms, we know better why patients respond so differently to the same treatments. So, in the future we can develop increasingly personalized treatments to the patient and not the disease. This review aims to summarize some molecular pathways and their relation to tumor growth, as well as novel targeted developing drugs and recently approved for mCRC.

Metastatic colorectal cancer treatment patterns according to kirsten rat sarcoma viral oncogene homolog genotype in U.S. Community-based oncology practices

INTRODUCTION

In 2008, the National Comprehensive Cancer Network guidelines were revised in light of the identification of the Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene as a biomarker of nonresponse to epidermal growth factor receptor inhibitors. This study sought to describe and compare real-world treatment patterns of metastatic colorectal cancer (mCRC) according to KRAS genotype in community-based oncology practices in the United States.

MATERIALS AND METHODS

Data from the ACORN (ACORN LLC, Memphis, TN) electronic medical record data warehouse, containing data of approximately 180,000 patients from 12 oncology practices across the United States were used. Records of adult patients with mCRC who had undergone KRAS testing between January 2008 and December 2011 were evaluated. Patient demographic characteristics, KRAS genotype, and treatment patterns were identified and compared.

RESULTS

Six hundred forty-eight mCRC patients who were tested for KRAS were identified. Of these, 48.1% had wild type (WT), 42.3% mutant, and 9.6% unknown genotypes. Most patients (72.1%) were tested in 2009 or later, after the guideline revision. Bevacizumab-containing combinations were the most common first-line regimens in KRAS mutant and WT patients. Approximately 90% of patients received at least 1 line of therapy, however, WT patients received significantly more lines of therapy than KRAS mutant patients (2.6 ± 1.5 vs. 2.1 ± 1.2; P < .001).

CONCLUSIONS

KRAS WT and mutant genotypes had similar first-line regimens; however, WT patients received more lines of therapy. Although there does not appear to be a lag between changes in guidelines and treatment practice, professional and government organizations must keep up with the changing science and disseminate this information to oncologists in a timely manner.

[Chronotherapy with 5-fluorouracil folinic acid and oxaliplatin delivered over 48 hours every second week in colorectal cancer. The CHC-Liège experience (Belgium)]

One hundred and ten consecutive patients suffering from a colorectal cancer received chronotherapy infused over two days every two weeks. Each course comported 5 FU 3g/m(2), folinic acid (600 mg/m(2) - l. form or 1200 mg/m(2)--racemic form) and oxaliplatin (85/mg/m(2)--adjuvant indication or 100mg/m(2)--palliative indication). According to chronobiological concepts, 5 FU and folinic acid were infused from 10 pm to 10 am with a peak at 4 am while oxaliplatin was delivered from 10 am to 10 pm with a peak at 4 pm. The overall tolerance was excellent with a maximum of 17% patients experiencing a grade 3 toxicity. The toxicity was higher in women, in older patients (>=70) or in case of flat infusion. In adjuvant situation (60 cases), progression free and overall survivals established respectively at 76% (42+months) and 88% (45+months). Fifty-two percent response rate were recorded within the palliative group (50 cases) with an overall 68% disease control. Median progression free survival was seven months but median survival was not attained at 31+ months. Thirty percent patients could benefit from a curative surgery after chemotherapy. Older patients (>=70) experienced worsened survival. In conclusion, we think that our chrono-FOLFOX 2-12 should be proposed as standard treatment for colorectal cancer patients.

Phase I study of cetuximab, irinotecan, and vandetanib (ZD6474) as therapy for patients with previously treated metastastic colorectal cancer

Background

To determine the maximum tolerated dose (MTD) and safety, and explore efficacy and biomarkers of vandetanib with cetuximab and irinotecan in second-line metastatic colorectal cancer.

Methods

Vandetanib (an orally bioavailable VEGFR-2 and EGFR tyrosine kinases inhibitor) was combined at 100 mg, 200 mg, or 300 mg daily with standard dosed cetuximab and irinotecan (3+3 dose-escalation design). Ten patients were treated at the MTD and plasma angiogenesis biomarkers (VEGF, PlGF, bFGF, sVEGFR1, sVEGFR2, IL-1β, IL-6, IL-8, TNF-α, SDF1α) were measured before and after treatment.

Results

Twenty-seven patients were enrolled at 4 dose levels and the MTD. Two dose-limiting toxicities (grade 3 QTc prolongation and diarrhea) were detected at 300 mg of vandetanib with cetuximab and irinotecan resulting in 200 mg being the MTD. Seven percent of patients had a partial response, 59% stable disease and 34% progressed. Median progression-free survival was 3.6 months (95% CI, 3.2–5.6) and median overall survival was 10.5 months (95% CI, 5.1–20.7). Toxicities were fairly manageable with grade 3 or 4 diarrhea being most prominent (30%). Vandetanib and cetuximab treatment induced a sustained increase in plasma PlGF and a transient decrease in plasma sVEGFR1, but no changes in plasma VEGF and sVEGFR2.

Conclusions

Vandetanib can be safely combined with cetuximab and irinotecan for metastatic colorectal cancer. Exploratory biomarker analyses suggest differential effects on certain plasma biomarkers for VEGFR inhibition when combined with EGFR blockade and a potential correlation between baseline sVEGFR1 and response. However, while the primary endpoint was safety, the observed efficacy raises concern for moving forward with this combination.

Trial Registration

Clinicaltrials.gov NCT00436072.

Regorafenib (BAY 73-4506) in advanced colorectal cancer: a phase I study

BACKGROUND

In a phase I dose-escalation study, regorafenib demonstrated tolerability and antitumour activity in solid tumour patients. The study was expanded to focus on patients with metastatic colorectal cancer (CRC).

METHODS

Patients received oral regorafenib 60-220 mg daily (160 mg daily in the extension cohort) in cycles of 21 days on, 7 days off treatment. Assessments included toxicity, response, pharmacokinetics and pharmacodynamics.

RESULTS

Thirty-eight patients with heavily pretreated CRC (median 4 prior lines of therapy, range 0-7) were enrolled in the dose-escalation and extension phases; 26 patients received regorafenib 160 mg daily. Median treatment duration was 53 days (range 7-280 days). The most common treatment-related toxicities included hand-foot skin reaction, fatigue, voice change and rash. Twenty-seven patients were evaluable for response: 1 achieved partial response and 19 had stable disease. Median progression-free survival was 107 days (95% CI, 66-161). At steady state, regorafenib and its active metabolites had similar systemic exposure. Pharmacodynamic assessment indicated decreased tumour perfusion in most patients.

CONCLUSION

Regorafenib showed tolerability and antitumour activity in patients with metastatic CRC. This expanded-cohort phase I study provided the foundation for further clinical trials of regorafenib in this patient population.

Molecular events in primary and metastatic colorectal carcinoma: a review

Colorectal cancer (CRC) is a heterogeneous disease, developing through a multipathway sequence of events guided by clonal selections. Pathways included in the development of CRC may be broadly categorized into (a) genomic instability, including chromosomal instability (CIN), microsatellite instability (MSI), and CpG island methylator phenotype (CIMP), (b) genomic mutations including suppression of tumour suppressor genes and activation of tumour oncogenes, (c) microRNA, and (d) epigenetic changes. As cancer becomes more advanced, invasion and metastases are facilitated through the epithelial-mesenchymal transition (EMT), with additional genetic alterations. Despite ongoing identification of genetic and epigenetic markers and the understanding of alternative pathways involved in the development and progression of this disease, CRC remains the second highest cause of malignancy-related mortality in Canada. The molecular events that underlie the tumorigenesis of primary and metastatic colorectal carcinoma are detailed in this manuscript.

Personalized colon cancer care in 2010

Colon cancer (CC) therapies have improved patient outcomes significantly over the last decades in both the adjuvant and metastatic settings. With the introduction of a number of novel agents, both traditional chemotherapies and biologically targeted agents, the need to identify subgroups that are likely and not likely to respond to a particular treatment regimen is paramount. This will allow patients who are likely to benefit to receive optimal care, while sparing those unlikely to benefit from unnecessary toxicity and cost. With the identification of several novel biomarkers and a variety of technologies to interrogate the genome, we already are able to rapidly study patient tumor or blood samples and normal tissues to generate a large dataset of aberrations within the cancer. How to digest this complex information to obtain accurate, reliable, and meaningful results that will allow us to provide truly personalized care for CC patients is just starting to be addressed. In this article, we briefly review the history of CC treatment, with an emphasis on current clinical standards that incorporate a "personalized medicine" approach. We then review strategies that will potentially improve our ability to individualize therapy in the future.

A Phase Ib pharmacokinetic study of the anti-angiogenic agent CKD-732 used in combination with capecitabine and oxaliplatin (XELOX) in metastatic colorectal cancer patients who progressed on irinotecan-based chemotherapy

BACKGROUND

We conducted a Phase I clinical trial to evaluate the safety, tolerability, and pharmacokinetics (PK) of CKD-732 [6-O-(4-dimethylaminoethoxy) cinnamoyl fumagillol hemioxalate] in combination with capecitabine and oxaliplatin (XELOX) in nine metastatic colorectal cancer patients who had progressed on irinotecan-based chemotherapy.

METHODS

Using a dose-escalation schedule, CKD-732 doses of 2, 5, or 10 mg/m(2)/d were administered twice weekly for 2 weeks, followed by a 1-week rest. Oxaliplatin (130 mg/m(2)) was administered on day 1, and capecitabine (1,000 mg/m(2) twice a day) was orally administered for 14 days of a 3-week cycle.

RESULTS

In the group given the 10 mg/m(2)/d dose, two patients experienced dose limiting toxicities (one had grade 3 nausea, insomnia, and fatigue; the other had grade 3 insomnia). The maximum tolerated dose was 10 mg/m(2)/d, and the clinically recommended dose was 5 mg/m(2)/d for CKD-732 in combination with XELOX. Frequently encountered non-hematological grade 3/4 adverse events included insomnia (22.2%), fatigue (11.1%), sensory neuropathy (11.1%), hyperbilirubinemia (11.1%), and dyspnea (11.1%). The area under the concentration-time curve and maximum concentration of CKD-732 increased in a dose-dependent manner. There were no notable effects of CKD-732 on the PK of capecitabine and oxaliplatin-derived platinum.

CONCLUSION

The Phase II recommended dose of CKD-732 was determined to be 5 mg/m(2)/d, and this dose was safely combined with a conventional dose of capecitabine and oxaliplatin in this patient population. Further studies on the effects of CKD-732 in combination with XELOX and other chemotherapies using a larger study population are warranted.

Biomarker-based prediction of response to therapy for colorectal cancer: current perspective

The diagnosis and management of colorectal cancer (CRC) has been impacted by the discovery and validation of a wide variety of biomarkers designed to facilitate a personalized approach for the treatment of the disease. Recently, CRC has been reclassified based on molecular analyses of various genes and proteins capable of separating morphologic types of tumors into molecular categories. At the same time, a number of new prognostic and predictive single genes and proteins have been discovered that are designed to reflect sensitivity and/or resistance to existing therapies. Multigene predictors have also been developed to predict the risk of relapse for intermediate-stage CRC after completion of surgical extirpation. More recently, a number of biomarkers tested by a variety of methods have been proposed as specific predictors of chemotherapy and radiotherapy response. Other markers have been successfully used to predict toxic effects of standard therapies. In this review, a series of novel biomarkers are considered and compared with standard-of-care markers for their potential use as pharmacogenomic and pharmacogenetic predictors of disease outcome.