Patient preferences and predicted relative uptake for targeted therapies in metastatic colorectal cancer: a discrete choice experiment

Abstract

Objective

Ras wild-type metastatic colorectal cancers (mCRC) may be treated with anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor receptor (EGFR) agents. We aim to estimate patients’ preferences for mCRC treatment and relative importance of cost, efficacy improvement, avoidance of side effects and therapy convenience, and relative uptake between profiles that resemble Bevacizumab (anti-VEGF) and Cetuximab (anti-EGFR), two commonly prescribed mCRC targeted therapies.     

Advanced therapies on BRAF-mutated and KRAS-mutated metastatic colorectal cancer

Colorectal cancer(CRC) is one of the most-diagnosed cancer worldwide, and 30% of patients with CRC have showed a metastatic situation. Monoclonal antibodies(mAbs) that target vascular endothelial growth factor(VEGF) and the epidermal growth factor receptor(EGFR) can achieveantitumor efficacy via antivascular and anticellular effects respectively and have been added into first-line chemotherapy for patients with metastatic colorectal cancer(mCRC). Investigations found that unlike VEGF inhibitors, the efficacy of EGFR inhibitors,such as Cetuximab and panitumumab, is limited to patients with wild-type-KRAS tumors without BRAF mutant. Studies revealed that resistance to EGFR inhibitors result in the poor response to anti-EGFR therapiesthrough acquired mutations of KRAS and BRAF.Considering this situation, in this review, we will focus onresistance mechanism to anti-EGFR therapies and advanced therapies for BRAF-mutated and KRAS-mutated mCRC patients.     

Antiepidermal growth factor receptor monoclonal antibody improves survival outcomes in the treatment of patients with metastatic colorectal cancer

The aim of this study was to determine whether or not the addition of anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibody (mAb) to standard chemotherapy or best supportive care (BSC), compared with chemotherapy or BSC alone, can improve overall survival (OS) and progression-free survival (PFS) in patients with metastatic colorectal cancer (mCRC), and evaluate the influence of KRAS mutant status on the efficacy of anti-EGFR mAb. Medline, Embase, the Cochrane controlled trials register, and the Science Citation Index were searched. Nine trials were identified, covering a total of 7941 patients. The treatment of mCRC with a combination of anti-EGFR mAb and chemotherapy or BSC, as compared with chemotherapy or BSC alone, improved the OS [hazard ratio (HR), 0.90 (0.84-0.96); P=0.002]. The benefit of anti-EGFR mAb in patients with KRAS wild-type tumors was apparent in relation to a marginal trend toward improved OS [HR, 0.84 (0.70-1.01); P=0.06], and significantly improved PFS [HR, 0.64 (0.51-0.81); P<0.001]. No benefit for the addition of anti-EGFR mAb was detected for any efficacy end-point in patients with KRAS mutant tumors. The summary HRs (anti-EGFR mAb vs control) were 0.98 (0.88-1.08) (P=0.71) for OS and 1.08 (0.94-1.25) (P=0.27) for PFS, respectively. In conclusion, this analysis provides confirmation that, compared with chemotherapy or BSC alone, anti-EGFR mAb with chemotherapy or BSC reduces the risk of progression and death of mCRC and that this benefit is seen only in patients with wild-type KRAS tumors.     

Targeted cancer therapies based on antibodies directed against epidermal growth factor receptor： status and perspectives

Compelling experimental and clinical evidence suggests that epidermal growth factor receptor （EGFR） plays an important role in the pathogenesis of a variety of human cancers; thus, providing a strong rationale for the development of receptor antagonists as effective and specific therapeutic strategies for the treatment of EGFR-expressing cancers. Monoclonal antibodies （mAb）, owing to their high specificity towards a given target, represent a unique class of novel cancer therapeutics. A number of anti-EGFR mAb are currently being developed in our clinic, including two that have been approved by the United States Food and Drug Administration for the treatment of refractory metastatic colorectal cancer （mCRC） and squamous cell carcinomas of the head and neck （SCCHN）. Cetuximab （Erbitux, IMC-C225）, an IgG 1 mAb, has demonstrated significant antitumor activity, both as a single agent and in combination with chemotherapeutics and radiation, in patients with refractory mCRC and SCCHN, respectively. Panitumumab （Vectibix）, an IgG2 mAb, has been approved as a single agent for the treatment of patients with refractory mCRC. These mAb, via blocking ligand/receptor interactions, exert their biological activity via multiple mechanisms, including inhibition of cell cycle progression, potentiation of cell apoptosis, inhibition of DNA repair, inhibition of angiogenesis, tumor cell invasion and metastasis and, potentially, induction of immunological effector mechanisms. Anti-EGFR antibodies have demonstrated good safety profiles and potent anticancer activity in our clinic and may prove to be efficacious agents in the treatment of a variety of human malignancies.     

Targeting epidermal growth factor receptor in the treatment of non-small-cell lung cancer

Importance of the field: The management of non-small-cell lung cancer (NSCLC) has undergone a paradigm shift in the last decade, with the survival advantage demonstrated by the incorporation of anti-epidermal growth factor receptor (EGFR) agents to the standard treatment of advanced/metastatic NSCLC.

Areas covered in this review: We review the existing data regarding the distinct anti-EGFR agents in the NSCLC treatment and the potential role of the investigated biomarkers in the clinical outcome.

What the reader will gain: Tyrosine kinase inhibitors have been used in first-line, second-line and more settings with extremely good results in a subgroup of patients. Cetuximab remains the only anti-EGFR monoclonal antibody to show survival benefit when combined with a cytotoxic agent in the front-line setting. Anti-EGFR treatment is associated with a dramatic clinical benefit in a subgroup of patients, emphasizing the importance of customizing treatment. Several biomarkers have been investigated for their predictive or prognostic value. Validation of identification of biomarkers remains a focus of intense research that may ultimately guide therapeutic decision making, as none of these is considered ideal to discriminate responding from non-responding patients. However, the current evidence of the EGFR mutation analysis from a recent randomised trial suggests that EGFR mutation analysis is quite a good predictive marker for responsiveness to anti-EGFR TKIs. Moreover, the identification of surrogate markers to indicate optimal activity of the anti-EGFR agent is also needed. This review article provides data from large clinical trials using anti-EGFR agents and correlates these results with the tested biomarkers.

Take home message: EGFR inhibition has shown very encouraging results and has improved the outcome of the NSCLC treatment. However, a plateau of significant clinical benefit seems to have been reached and we believe that the time to move away from the traditional treatment approach to more individualizing therapies has come.     

Triple-drug chemotherapy regimens in combination with an anti-EGFR agent in metastatic colorectal cancer - prospects from phase II clinical trials

Introduction: The addition of monoclonal antibody (mAb) epidermal growth factor receptor (EGFR) inhibitors to classic chemotherapy doublet backbones has improved survival of metastatic colorectal cancer (mCRC). However, the role of triple-drug chemotherapy regimens in combination with an anti-EGFR mAb inhibitor is not yet clear.

Areas covered: The activity of triple-drug chemotherapy regimens when combined with an anti-EGFR mAb in mCRC patients is examined. We describe the overall safety and tolerability profiles based on a literature review of all published phase I and II clinical trials in this setting. Drug exposure, tumor mutational status, and metastases resectability are discussed. A review of PubMed and abstracts of major oncology congresses from 2009 to 2018, with MeSH and full-text search terms for clinical trials of anti-EGFR for ‘metastatic’ or ‘advanced’ ‘colorectal cancer/adenocarcinoma’ was implemented. Only English language publications were included.

Expert opinion: Efficacy data from phase II trials are promising, but the safety profiles are not as encouraging; the development of severe diarrhea and acneiform rash limit the drug exposure that is critical for improved outcomes. Phase II studies of these triplet chemotherapy/anti-EGFR mAb combinations have focused on conversion therapy in liver-limited disease or in the first-line setting in advanced disease. The identification of biomarkers of response and toxicity may support the use of personalized medicine and more precise design of phase III trials.     

Epidermal growth factor receptor tyrosine kinase inhibitors as anticancer agents

The epidermal growth factor receptor (EGFR)-driven autocrine growth pathway has been implicated in the development and progression of the majority of the most common human epithelial cancers, making the blockade of this growth pathway a promising anticancer therapeutic strategy. Different approaches have been developed to block EGFR activation and/or function in cancer cells. In the past 15 years, various anti-EGFR blocking monoclonal antibodies (MAb), recombinant proteins containing transforming growth factor-alpha (TGFalpha) or EGF fused to toxins, and tyrosine kinase inhibitors (TKIs) have been generated and their biological and potentially therapeutic properties characterised. One of these agents, MAb IMC-C225, a chimeric human-mouse IgG1 MAb, is the first anti-EGFR agent to enter phase II to III clinical trials in patients with cancer. Several small compounds that block the ligand-induced activation of the EGFR tyrosine kinase have been developed. Among these EGFR-TKIs, various quinazoline-derived agents have been synthesised and have shown promising activity as anticancer agents in preclinical models. ZD1839 ('Iressa'), an anilinoquinazoline, is an orally active, selective EGFR-TKI which is currently under clinical evaluation in phase II to III clinical trials in patients with cancer. Preclinical data for ZD1839 strongly support the possibility of potentiating the antitumour activity of conventional chemotherapy with agents that selectively block the EGFR.     

VEGF inhibitors in cancer therapy

Vascular endothelial growth factor (VEGF)-mediated angiogenesis is thought to play a critical role in tumor growth and metastasis. Consequently, anti-VEGF therapies are being actively investigated as potential anti-cancer treatments, either as alternatives or adjuncts to conventional chemo or radiation therapy. Among the techniques used to block the VEGF pathway are: 1) neutralizing monoclonal antibodies against VEGF or its receptor, 2) small molecule tyrosine kinase inhibitors of VEGF receptors, 3) soluble VEGF receptors which act as decoy receptors for VEGF, and 4) ribozymes which specifically target VEGF mRNA. Recent evidence from phase III clinical trials led to the approval of bevacizumab, an anti-VEGF monoclonal antibody, by the FDA as first line therapy in metastatic colorectal carcinoma in combination with other chemotherapeutic agents. However, may challenges still remain, and the role of anti-VEGF therapy in the treatment of other solid tumors remains to be elucidated. The aim of this article is to review the progress of clinical investigations involving VEGF inhibitors in the treatment of different types of solid tumors.     

Targeted therapies in non-small cell lung cancer: proven concepts and unfulfilled promises

Targeted therapies focus on signaling pathways in cancer cells and other molecular processes involved in oncogenesis. Recent approaches affect the following major groups: the epidermal growth factor receptor (EGFR)-family, angiogenesis, the eicosanoid pathway, the PKC/ Ras/ MAPK pathway, the proteasome and inducers of apoptosis. Numerous phase I and II trials have provided promising results and recently, anti-EGFR and anti-VEGF treatments have proven their efficacy in phase III trials. However, others failed in phase III settings (e.g. PKC- and matrix metalloproteinase inhibitors) and it is a moot point, whether patients have been selected properly. The huge amount of new medications raises questions like when to use which strategy in which sequence. The successful implementation of targeted agents into clinical routine will depend on the verification of sufficient predictive markers, allowing their economically reasonable usage. In the current review the up-to-date knowledge concerning targeted therapies in NSCLC is summarized and their therapeutical potential is discussed.     

Rational combination of targeted therapies as a strategy to overcome the mechanisms of resistance to inhibitors of EGFR signaling

The epidermal growth factor receptor (EGFR) has been widely used as a target for novel anticancer agents, such as blocking antibodies and small molecular weight tyrosine kinase compounds. In spite of recent advances in cancer cell biology, leading to the introduction of clinically active new drugs, such as cetuximab, panitumumab and erlotinib, unfortunately disease control remains unsuccessful due to the presence of constitutive resistance to EGFR inhibitors in most patients and the development of acquired resistance in the responders. A large number of molecular abnormalities in tumor cells seem to partly contribute to their resistance to anti-EGFR therapy: increased angiogenesis, constitutive activation of downstream mediators, overexpression of other tyrosine kinase receptors. Moreover, some mutations in the EGFR receptor kinase domain seem to play a crucial role in determining the sensitivity of cancer cells to specific inhibitors by altering the conformation of the receptor and its activity. The development of rational combinations of anticancer agents and EGFR inhibitors, able to exert synergistic cytotoxic interactions, has been widely accepted and used in both preclinical and clinical studies. Although the failure of large clinical trial based on empirical combination of anti-EGFR and classic chemotherapeutic agents, several preclinical data seems to support the hypothesis that combining EGFR inhibitors and other novel agents could efficiently inhibit tumor growth and overcome intrinsic resistance to a single-agent based therapy. This review focuses on the role of complementary signalling pathways in the development of resistance to EGFR targeting agents and the rationale to combine novel inhibitors as anticancer therapy.     

Anti-angiogenesis drugs in diabetic retinopathy

The vascular endothelial growth factor (VEGF) plays a key role in the development of proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME), resulting in a significant visual loss among patients with diabetes mellitus. Systemic VEGF-A and the interplay between membrane-bound VEGF receptors and VEGF-R1 (soluble form) are key to angiogenesis and vasculogenesis. Furthermore, patients with diabetes have a higher risk of hypertension and proteinuria, two surrogate markers of systemic VEGF inhibition. Pegaptanib, ranibizumab, bevacizumab and roboxistaurin are the currently available anti-VEGF agents. Agents with activity occurring later down the angiogenic pathway and those drugs with potential to synergize with anti-VEGF-A technologies are being developed. In recent years, inhibition of ocular VEGF has emerged as a promising treatment modality for diabetes and is currently undergoing evaluation in clinical trials. A potential role for these anti-VEGF agents in the prevention of PDR and DME are also emerging.     

Patient-tailored treatments with anti-EGFR monoclonal antibodies in advanced colorectal cancer: KRAS and beyond

Personalized medicine emphasizes the practice of considering individual patient characteristics as opposed to that centered on standards derived from epidemiological studies which, by definition, do not take into account the variability of individuals within a given population. When applied to oncology, personalized medicine is an even more complex concept because it extends the variability beyond the individual patient to the individual tumor. Indeed, the great genotypic and phenotypic variability (both in primary and metastatic sites of cancer) the development of targeted therapies, and the growing availability of biological assays complicate the scenario of personalized medicine in the oncological field. In this paper we review the results of anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) therapy in metastatic colorectal cancer (mCRC) in the context of tumor biology, delineating the future prospects of patient-tailored medicine in this area. In particular, we deal with EGFR inhibition by Cetuximab, a chimeric mouse human IgG1 mAb, and panitumumab, a fully human IgG2 mAb. We discuss the clinical impact of anti-EGFR mAbs on wild-type (WT) KRAS mCRC, also taking into account the feasibility of novel multi-marker approaches to treatment decision-making, aimed at increasing the predictive power of pre-therapy biomarkers. Experimental topics and fields of ongoing research, such as targeting microRNAs (miRNAs) with novel anticancer drugs and epigenetics in CRC are also addressed.     

Safety and efficacy of nintedanib for the treatment of metastatic colorectal cancer

Introduction: Nintedanib (BIBF 1200) is an oral tyrosine kinase inhibitor that targets the vascular endothelial growth factor (VEGFR), platelet-derived growth factor (PDGFR) and fibroblast growth factor (FGFR) receptors. It is approved in Europe in combination with docetaxel for patients with advanced lung adenocarcinoma who have progressed to first-line chemotherapy. However, its role in the treatment of metastatic colorectal cancer (mCRC) is uncertain. Recent results from the LUME-Colon 1 pivotal phase III trial showed only a marginal increase in progression free survival over placebo in refractory mCRC patients, with a toxicity profile similar to other antiangiogenic agents, and no benefit in overall survival.

Areas covered: The aim of this review is to summarize the pharmacology, efficacy and safety profile of nintedanib in the context of mCRC, and to provide some perspective regarding the role of this drug in clinical practice.

Expert commentary: Nintedanib provides limited clinical benefit in refractory CRC and its use in this clinical setting is not warranted. Efforts shall continue to pursue the identification of predictive biomarkers that allow the selection of subpopulations with a greater likelihood to benefit from this therapeutic approach, in order to improve the benefit-risk and cost-benefit ratios of this and other antiangiogenic agents.     

Therapies directed at vascular endothelial growth factor

The inhibition of angiogenesis through vascular endothelial growth factor (VEGF) receptor targeting is a strategy that is relatively tumour selective. The high selectivity achieved with neutralising antibodies, soluble receptors and ribozymes reduces the risk of adverse reactions not related to VEGF inhibition itself. Small-molecule, orally-active protein kinase inhibitors provide an attractive alternative for chronic therapy, although specifically targeting a small subset of protein kinases from the approximately 550 expressed in mammalian cells is a challenge. Current efforts have resulted in promising clinical data for several synthetic VEGF receptor kinase inhibitors, of which PTK787/ZK222584 and ZD6474 are proceeding into large size clinical trials. It seems likely that blockers of the VEGF signalling pathway will be unsuitable for monotherapy, and that their role will be as an adjunct to additional antiangiogenic agents together with directly-acting antitumour agents or radiation therapy. Caution is needed with combinations of anti-VEGF therapies and cytotoxic agents, as coadministration of cytotoxic agents with either the kinase inhibitor SU5416 or the VEGF antibody avastin appears to be associated with bleeding and thrombotic adverse events.     

Palliative treatment of unresectable metastatic colorectal cancer

Importance of the field: Treatment options for metastatic colorectal cancer (mCRC) patients have rapidly increased in the past years, but 50 – 70% of mCRC patients are still unlikely to undergo radical resection of metastases and are candidates for palliative therapy only.

Areas covered in this review: Oxaliplatin and irinotecan have widened the chemotherapy alternatives available in this setting and effective targeted agents against vascular endothelial growth factor and epidermal growth factor receptor have further improved treatment efficacy. This review covers the main areas of debate in the optimal treatment of unresectable mCRC patients, focusing on the implications for everyday clinical practice and future research of the most relevant clinical trials and molecular investigations published from 1999 to 2009.

What the reader will gain: Insights into treatment individualization strategies are provided in the review.

Take home message: ‘One size fits all’ can not longer be considered an adequate approach to unresectable mCRC, and treatment with both chemotherapy and biologic agents should be guided by prognostic and predictive factors in order to maximize the benefit while reducing futile toxicities.     

An overview of experimental and investigational multikinase inhibitors for the treatment of metastatic colorectal cancer

Introduction: The era of molecular-targeted agents, particularly bevacizumab and cetuximab, has revolutionized the treatment paradigm for metastatic colorectal cancer (mCRC). Amongst the multikinase inhibitors (MKIs) examined, regorafenib was the first to establish its role in mCRC. Despite its modest efficacy, this finding had reignited interest in exploring MKIs with the hope of maximizing their therapeutic potential in mCRC.

Areas covered: This review summarizes the previous studies of MKIs in mCRC, targeting two signaling pathways activated through vascular endothelial growth factor receptors and epidermal growth factor receptors. The article provides discussion with a focus on: the challenges encountered when combining MKI with chemotherapy, the lack of predictive markers, and strategies utilized to address escape pathways through combining MKIs with other targeted agents.

Expert opinion: Clinical progress using MKIs in mCRC has been disappointing due to their limited efficacy. The exact role of regorafenib, apart from in chemo-refractory disease setting, requires further delineation. The role of MKIs in combination with other targeted agents or chemotherapy and in the maintenance setting is still considered experimental and warrants further investigation. The broader role of the current generation of MKIs will depend upon the accurate identification of patients with specific molecular phenotypes and better pharmacodynamic understanding of these agents to minimize toxicity.     

Anti-epidermal growth factor receptor strategies to enhance radiation action

The epidermal growth factor receptor (EGFR) has emerged as a central molecular target for modulation in cancer therapeutics, since EGFR signaling affects many factors that in turn promote tumor growth, progression and metastasis. In addition, radiobiological investigations have also defined a critical role for EGFR in mediating cytoprotective and pro-proliferative responses in human cancer cells after ionizing radiation, that contribute at least in part to accelerated tumor cell repopulation. This led to the additional development of EGFR as a target to enhance radiation efficacy. Several anti-EGFR strategies have been put forth demonstrating a favorable biological interaction between EGFR blockade and radiation. However, further preclinical investigations are necessary to better explore mechanisms of action and efficacy of combined treatment modalities. Although some of the anti-EGFR approaches have already reached clinical testing in combination with radiation, it is still too early to establish a clinical proof for the ultimate role of EGFR inhibition in combination with radiation. This article focuses primarily on anti-EGFR approaches to modulate radiation response.     

Anti-VEGF compounds in the treatment of neovascular age related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness among elderly patients in developed countries. Although the pathogenesis of AMD is still largely unknown, it is now well known that vascular endothelial growth factor (VEGF) plays a pivotal role in the growth of the abnormal blood vessels (i.e. choroidal neovascularization, CNV) which characterizes the "wet form" of this ocular disease. Therefore, inhibiting VEGF has turned out to be a good way of more effectively controlling neovascular AMD. VEGF is a heparin-binding glycoprotein with potent angiogenic, mitogenic and vascular permeability-enhancing activities specific for endothelial cells. Currently two anti-VEGF compounds have been approved by the US Food and Drug Administration (FDA) for the treatment of neovascular AMD: pegaptanib and ranibizumab. Off-label usage of bevacizumab, an anti-VEGF agent similar to ranibizumab, has also become fairly common. The substantial improvement of visual acuity noticed in patients treated with ranibizumab has made this drug the gold standard for AMD therapy. However, as with many new therapies, there are unresolved issues, including safety, cost, and dosing frequency. This review describes in details the properties and efficacy of the three anti-VEGF agents in use in clinical practice. Promising emerging anti-VEGF strategies (VEGF-trap, small interfering RNA, tyrosine kinase inhibitors) which aim to improve outcomes, safety and treatment burden through novel mechanisms of action are also discussed.     

KRAS mutations predict response to EGFR inhibitors

Five antiepidermal growth factor receptor therapies have been approved for the treatment of solid tumors. However, response rates are relatively low. Several biomarkers that enrich for patients with tumors most likely to respond to these therapeutic agents have been identified. Mutations in the intermediate signal transduction pathway member KRAS also selects patients with tumors depending on signaling through this pathway. However, because KRAS acts downstream of the EGF receptor, somatic changes in this gene can be used as a marker to exclude patients unlikely to benefit from anti-EGFR therapy. Recent clinical data have provided substantial evidence that KRAS mutational status should be utilized as a diagnostic marker for predicting that response to anti-EGFR therapies in colorectal and non-small cell lung cancer.