Emerging VEGF-receptor inhibitors for colorectal cancer

Introduction: Targeted agents have dramatically improved and enriched the therapeutical choices for patients with metastatic colorectal cancer (mCRC). By better understanding the role of the angiogenic pathway in colorectal cancer (CRC), new therapies have been developed. Bevacizumab, the first anti-angiogenetic agent approved for the treatment of mCRC provide a proof of concept since it has improved the progression-free survival and overall survival when combined with cytotoxic chemotherapy.

Areas covered: This review is focused on the most recent findings on the VEGF signaling pathway and new therapeutic drugs explored in clinical trials.

Expert opinion: Despite the advantage offered by bevacizumab, the median overall survival of mCRC patient exceeds 21 months; thus, investigational efforts are needed. Several antiangiogenic agents for the treatment of mCRC are being tested in preclinical and clinical Phase I/II trials. Unfortunately a discrete number of Phase III trials produced negative results. Recently aflibercept and regorafenib, two new antiangiogenic drugs, have been approved as the new-targeted agents for the treatment of mCRC, according to the positive findings from the VELOUR and the CORRECT studies. In order to maximize clinical impact it will be important to validate predictive biomarkers and best combination treatments to offer for mCRC patients; further research and intense investigation is still required.     

Beyond bevacizumab: new anti-VEGF strategies in colorectal cancer

INTRODUCTION: Treatment of colorectal cancer (CRC) has changed dramatically over the past decade, mainly due to the advent of molecularly targeted agents. In particular, an improved understanding of the role of the angiogenesis pathway in CRC has led to advancements in treatment. Bevacizumab has been shown to improve the progression-free survival and overall survival when combined with cytotoxic chemotherapy in patients with metastatic CRC (mCRC) and at present is the only antiangiogenesis agent approved for the treatment of this cancer. AREAS COVERED: In this review, the authors outline the most recent data on the VEGF signaling pathway and on new therapeutic reagents that target it, provide insight into their mechanisms, and describe results from recent clinical trials. EXPERT OPINION: In the new decade of 'modern therapy', an increasing number of antiangiogenic agents for the treatment of mCRC are being tested in preclinical models, and dozens of studies on these drugs are ongoing. Presently, eight novel antiangiogenic agents are in Phase III trials and a wide range of other candidates are being tested in Phase I/II trials. Given the preliminary positive results of two recent Phase III trials, aflibercept and regorafenib, probably, will be new-targeted agents approved for the treatment of mCRC. Furthermore, the list of potentially approved agents seems to increase in the next years and to maximize their potential clinical impact, is critically important to introduce efficient molecular diagnostic methodologies into the drug development process to indentify the subset of patients who would benefit most from their use.     

Regorafenib in the treatment of colorectal cancer

Introduction: Colorectal cancer (CRC) is among the most frequently diagnosed malignancies, and is commonly associated with metastatic disease at presentation. While chemotherapy represents a mainstay of management, options at the time of disease progression are limited. Regorafenib is a novel multikinase inhibitor which has been evaluated for patients with chemo-refractory metastatic CRC (mCRC) and is currently approved for use in a last-line-of-treatment setting.

Areas covered: Articles searchable on MEDLINE/PubMed were reviewed to provide context for use of regorafenib in the management of mCRC. Specific drug properties are discussed, including chemistry, pharmacodynamics, pharmacokinetics, and metabolism. Additionally, clinical efficacy is reported with consideration of Phases I–III data.

Expert opinion: Phase III evaluation has confirmed the efficacy of regorafenib for patients with chemo-refractory mCRC. Importantly, the rapid accrual of the CORRECT trial revealed the degree of unmet need for this patient population, and proved that it was feasible to compare novel agents to placebo when multiple lines of standard therapy have failed. In the coming years, the role of regorafenib in the management of mCRC should be further clarified, especially through identification of the patient population with greatest anticipated benefit and exploration of its use as an adjuvant or maintenance agent.     

Angiogenesis inhibitors in the treatment of prostate cancer

Importance of the field: Prostate carcinoma is the most common non-cutaneous malignancy in U.S. men. The efficacy of docetaxel and prednisone in metastatic castrate-resistant prostate cancer (mCRPC) has been shown to improve overall survival; however, its effect is not durable, highlighting the need for new therapies.

Areas covered in this review: We will review the development of some of the leading compounds with direct and indirect antiangiogenic activity in prostate cancer including antibodies to VEGF and its receptors, small-molecule inhibitors of downstream signaling, immunomodulatory drugs with antiangiogenic activity, and compounds thought to directly inhibit or destroy vascular endothelial cells.

What the reader will gain: The reader will gain a basic understanding of the role of angiogenesis in prostate cancer growth and metastasis. Current and potential targets of angiogenesis and their corresponding drugs under development for prostate cancer are discussed.

Take home message: There are now multiple early-phase clinical trials of antiangiogenic agents alone or in combination in prostate cancer. Several of these agents are now in Phase III development. Combined therapy with two antiangiogenic compounds may improve the activity of either compound alone. Multiple targets in the angiogenesis pathway continue to be elucidated and should remain an active area of investigation for the treatment of prostate cancer.     

Sorafenib: a clinical and pharmacologic review

Importance of the field: Sorafenib is an oral receptor tyrosine kinase inhibitor that inhibits Raf serine/threonine kinases and receptor tyrosine kinases (vascular endothelial growth factor receptors 1, 2, 3 and platelet-derived growth factor-β, Flt-3 and c-kit) that are implicated in tumorigenesis and tumor progression. Sorafenib is approved for the treatment of advanced inoperable hepatocellular cancer and advanced renal cell cancer.

Areas covered in this review: The findings from the major Phase III studies that led to FDA approval of this drug for the above indications are reviewed. Key aspects of sorafenib pharmacology, dosing in the presence of organ dysfunction, toxicities and weaknesses of the research done so far are summarized.

What will the reader gain: The reader will have the knowledge of the major studies that form the basis of the clinical use of sorafenib, information on the upcoming Phase III trials that could lead to changes in clinical practice and some insights on aspects of the drugs' mechanism of action and toxicity that still remain unclear.

Take home message: Sorafenib is a well-tolerated oral antiangiogenic agent approved for treatment of two angiogenesis-driven cancers. Studies to broaden the clinical indications and increase understanding of the clinical and laboratory biomarkers of response are needed.     

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.     

Sirolimus for the treatment of noninfectious uveitis

Introduction: Noninfectious posterior uveitis (NIPU) remains a significant burden of legal blindness. Because of its immune mediated and chronic recurrent nature, common therapy includes (systemic) corticosteroids and immune modulatory agents. Most treatments bear the risk of significant adverse effects. Therefore efforts are made to administer therapeutic agents directly into the vitreous cavity. The purpose of this article is to identify the role of intravitreally applied sirolimus as a recently approved therapeutic option in NIPU.

Areas covered: A MEDLINE database search was conducted through August 2015 using the terms: intravitreal injection, pharmacology, sirolimus, treatment and uveitis. To provide ongoing and future perspectives in treatment options, also clinical trials as registered at ClinicalTrials.gov were included. Sirolimus (Opsiria) was in licensed from SANTEN in 2015 and approved in Phase III registration trials in the US, Europe and other countries for NIPU. Current information results mainly from registration and Phase III trials.

Expert opinion: Intravitreal sirolimus appears to be an interesting option in the treatment algorithms of NIPU because of its highly targeted molecular effects, nonsteroidal nature and good safety profile. It has the advantage to avoid systemic side effects, but this has to be balanced against the fact that treatment covers one eye only and bears the risks of any intraocular procedure. Nevertheless a careful evaluation of this agent has to be made, as current experience is almost exclusively based on registration trials and long-term effects still have to be explored.     

The safety of ramucirumab for the treatment of colorectal cancer

Introduction: Ramucirumab, a human monoclonal antibody against vascular endothelial growth factor receptor 2 (VEGFR-2), is an antiangiogenic therapy that has been approved in combination with FOLFIRI in second-line treatment of metastatic colorectal cancer (mCRC), after progression on or after therapy with bevacizumab, oxaliplatin, and a fluoropyrimidine. A thorough review of the safety of ramucirumab in this setting and in the context of other antiangiogenic agents is merited.

Areas covered: We provide an overview of activity and summarize in detail the overall safety and tolerability profile of ramucirumab in mCRC patients on the basis of a literature review of all published clinical trials in this setting, including both single-agent and combination studies. A focus on adverse events of interest and specific populations is included, as well as a critical comparison with other antiangiogenic therapies.

Expert opinion: As an effective agent in pretreated mCRC patients, the toxicity profile of ramucirumab is similar to those of other angiogenesis inhibitors used in the second-line mCRC setting. The next challenge will be to find biomarkers of response and toxicity to antiangiogenic therapies in order to more effectively implement personalized medicine in these patients.     

Pazopanib for the treatment of renal cancer

Introduction: Dramatic advances in the care of patients with advanced renal cell carcinoma (RCC) have occurred over the last 10 years. Insights into the molecular pathogenesis of this disease have elucidated the importance of signaling cascades related to angiogenesis in the management of RCC. Pazopanib is a novel, small-molecule tyrosine kinase inhibitor that targets vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3; platelet-derived growth factor receptors (PDGFR)-α and -β; and c-kit tyrosine kinases. Pazopanib exhibits distinct pharmacokinetic and toxicity profiles compared with other agents in the class of VEGF signaling pathway inhibitors.

Areas covered: This review discusses the scientific rationale for the development of pazopanib, as well as the preclinical and clinical trials that led to the approval of pazopanib for patients with advanced RCC. The most recent information, including data from the 2010 meeting of the American Society of Clinical Oncology and the design of ongoing Phase III trials, is discussed. Finally, an algorithm utilizing level I evidence for the treatment of patients with this disease is proposed.

Expert opinion: The treatment of metastatic RCC has changed dramatically over the last 5 years. Six novel agents – sunitinib, sorafenib, temsirolimus, everolimus, bevacizumab (used in combination with interferon), and pazopanib (Votrient) – have been approved for the treatment of metastatic RCC. The clinical data to date clearly place pazopanib among the most active of the targeted therapies.     

NX-1207: a novel investigational drug for the treatment of benign prostatic hyperplasia

Importance of the field: Lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) is a common affliction among older men that can have significant impact on health-related quality of life. BPH is a progressive condition that can lead to complications including acute urinary retention (AUR) and to surgical intervention. There is an ongoing need for new, safe and effective treatments for BPH. Currently available therapies have significant safety and efficacy limitations. NX-1207 is a promising first-in-class drug currently in Phase III trials for the treatment of BPH.

Areas covered in this review: This review provides an overview of BPH and currently approved medical treatments and drugs as described in the literature and treatment practice guidelines in the past 10 years, an outline of the results of the Phase II trials of NX-1207 and an expert opinion on the role NX-1207 may play in the treatment of men with clinical BPH.

What the reader will gain: This review aims to introduce readers to NX-1207, a new treatment for BPH that is administered in an office-based procedure by transrectal intraprostatic injection under ultrasound guidance. NX-1207 has selective pro-apoptotic properties, which induces focal cell loss in prostate leading to prostate volume reduction with both short- and long-term symptomatic improvement.

Take home message: In four US clinical trials to date, NX-1207 has shown evidence of symptomatic improvement substantially better than currently approved BPH medications with no significant safety issues. Larger Phase III trials are ongoing to further confirm the efficacy, safety and tolerability for this minimally invasive, anesthetic free, clinic-based treatment for BPH.     

Targeting IL-6 for the treatment of rheumatoid arthritis: Phase II investigational drugs

Introduction: IL-6 is a key cytokine in the pathogenesis of rheumatoid arthritis (RA). The clinical efficacy of tocilizumab (TCZ), a humanized anti-IL6-receptor mAb, confirmed the value of IL-6 blockade in this disease. A number of new anti-IL-6 biologics are currently in Phase I – III of clinical development for RA.

Areas covered: This article reviews the available results from Phase II trials of investigational anti-IL-6 agents in RA. The authors discuss the potential relevance of alternative IL-6-blocking agents, with regard to their specific molecular targets in IL-6 signaling pathways and to the main open questions in the clinical research agenda for anti-IL-6 biologics.

Expert opinion: The results of Phase II trials of new anti-IL-6 biologics show promising results in terms of efficacy. The most frequently reported adverse events were not unexpected based on previous experience with TCZ. Further evidence is needed to appraise whether the difference in molecular structure or in the specific target of new anti-IL-6 biologics might result in added therapeutic value over TCZ. New data from Phase III trials that provides a head-to-head comparison against TCZ and anti-TNF agents with or without methotrexate background treatment are expected in the future.     

The development of the tumor vascular-disrupting agent ASA404 (vadimezan,DMXAA): current status and future opportunities

Importance of the field: Targeting tumor vasculature with antiangiogenic agents improves outcomes achieved with chemotherapy in some cancers, but toxicity limits their applicability. Tumor vascular-disrupting agents (tumor-VDAs) induce an acute collapse in tumor vascular supply; ASA404 (vadimezan, 5,6-dimethylxanthenone-4-acetic acid [DMXAA]) is the tumor-VDA most advanced in clinical development. Recent randomized trials of ASA404 in combination with chemotherapy suggested a survival advantage in NSCLC comparable to that achieved with bevacizumab, but with little additional toxicity. Phase III trials in advanced NSCLC have completed accrual, and a review of this exciting agent is timely.

Areas covered in this review: This review focuses on the development of ASA404 to date, its mechanisms of action, the current body of clinical research and potential avenues for therapeutic use. It includes all completed clinical trials since it entered clinical testing in 1995 through to 2009.

What the reader will gain: This review will help the reader to understand why ASA404 is unique among tumor-VDAs; the clinical trial methodology required to evaluate such agents; and its remarkable potential clinical utility.

Take home message: ASA404 is a tumor-VDA that offers considerable potential to improve outcomes in cancer patients in combination with existing treatments.     

Emerging antiangiogenics for renal cancer

Introduction: Antiangiogenic therapy is considered to be the backbone of treatment strategy in metastatic renal cell carcinoma (mRCC). New, more focused, targeted drugs are emerging, while other targeted drugs oriented toward resistance or alternative mechanisms are under development.

Areas covered: Antiangiogenic agents include two types of agents: the monoclonal antibody, targeting vascular endothelial growth factor (VEGF), bevacizumab and the tyrosine kinase inhibitors (TKIs). Data regarding efficacy and safety of these agents are reported. Differences between the first generation of TKIs, sunitinib, sorafenib, and the new generation, pazopanib, axitinib and tivozanib are also detailed. Most of these agents have been approved in the treatment of kidney cancer in specific settings of the disease.

Expert opinion: The class of antiangiogenic drugs for treatment of mRCC is already relatively full. After ‘me-too' drugs, more targeted drugs against VEGFR have been developed but have to demonstrate a benefit in first-line treatment. Another option for the development is to combine a known drug with an antiangiogenic inhibition profile and at least one additional target involved in resistance to an antiangiogenic or in an alternative pathway. The cost of approach with targeted drugs, including antiangiogenics, has led to a tremendous increase in the cost of care in mRCC.     

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.     

Colorectal cancer in review: the role of the EGFR pathway

Importance of the field: The overexpression of EGFR has been documented in 30 – 90% of cases of advanced colorectal cancer (CRC). An increased understanding of the EGFR pathway in CRC has paved the way for the development of other targeted agents to augment therapeutic efficacy as well as for efforts to circumvent tumor resistance to therapy.

Areas covered in this review: Our aim is to discuss the recent progress in the role of the EGFR pathway, the status of anti-EGFR therapeutic agents currently in use and the rationale for the development of novel agents that work along the pathway for the treatment of CRC.

What the reader will gain: The readers will learn about the development and evolution of mAbs directed against EGFR as well as tyrosine kinase inhibitors in the management of CRC patients. In the same vein, determination of optimal dosing and better methods of defining those subsets of patients most likely to benefit will be discussed.

Take home message: All these data must encourage clinicians and basic researches to continue in their efforts to untangle the network behind EGFR and try to focus all that effort towards improving patient's quality of life as well as survival.     

Targeted delivery for breast cancer therapy: the history of nanoparticle-albumin-bound paclitaxel

Importance of the field: Taxanes are agents for the treatment of breast cancer. Paclitaxel is hydrophobic, and available formulations require polyoxyethylated castor oil, Cremphor EL^® (CrEL) and an ethanol vehicle to allow parental administration. Nanoparticle albumin-bound paclitaxel (nab-P) is a CrEL-free formulation of paclitaxel. The human albumin-stabilized paclitaxel particles have a size of approximately 130 nm, which allows intravenous infusion without capillary blockage.

Areas covered in this review: Efficacy and safety of nab-P in breast cancer has been compared with paclitaxel and docetaxel in large Phase III and II trials. Additionally, the efficacy and safety of nab-P have been investigated in other single-arm clinical trials, in early and advanced disease.

What the reader will gain: Preclinical and clinical development of the drug across all clinical trials published so far, the approved clinical indications, the benefits of this taxane formulation and a look into the future with emphasis on the application in specific subtypes of breast cancer.

Take home message: nab-P has been approved for the treatment of metastatic breast cancer in patients who have failed first-line treatment for metastatic disease and for whom standard, anthracycline-containing therapy is not indicated and represents one of most authoritative and sophisticated applications of nanotechnology in cancer treatment so far.     

Vinflunine: drug safety evaluation of this novel synthetic vinca alkaloid

Introduction: Vinca alkaloid agents have been widely used in several different types of malignancies. However, cancer cells, ultimately, develop resistance to these agents. Therefore, the development of new agents with improved efficacy is warranted. Recently, a new synthetic vinca alkaloid, vinflunine, was developed through the addition of two fluor molecules by superacidic chemistry.

Areas covered: The authors describe the development of the new vinca alkaloid vinflunine from preclinical studies to the late-stage clinical trials, highlighting the most important clinical and safety data of vinflunine. In vitro and in vivo studies have shown a superior efficacy of vinflunine over other vinca alkaloids and with an improved safety profile. Early clinical trials have demonstrated a significant activity of vinflunine against different malignancies. Phase III trials showed that vinflunine increases survival in patients with advanced transitional cell carcinoma of the urothelium (TCCU) tract treated in the second-line and is as effective as docetaxel in second-line NSCLC.

Expert opinion: Vinflunine is currently approved in Europe for the treatment of second-line TCCU and is currently being developed in other malignancies. It has been shown to have predictable and manageable adverse effects, such as neutropenia, anemia, constipation and fatigue.     

Novel integrase inhibitors for HIV

Importance of the field: Integrase inhibitors are the newest class of antiretroviral agents developed to treat HIV-1 infection. Raltegravir (RAL), the only integrase inhibitor (INI) currently approved for the treatment of HIV-infected patients, has proven to be a potent and well-tolerated antiretroviral (ARV) agent. It is currently approved and used for the treatment of both ARV-experienced and ARV-naive patients. Nevertheless, the relatively low genetic barrier for resistance of RAL encourages the search for new INIs with different mechanisms of actions and resistance profiles.

Areas covered in this review: Here we review the data available about INI that are currently being tested in clinical trials or are in preclinical development: elvitegravir (EVG), S/GSK1349572, S/GSK1265744 and LEDGINs. We focus on their clinical efficacy, pharmacokinetic, safety and resistance profiles.

What the reader will gain: Up-to-date overview on the currently available, clinically relevant INIs and promising preclinical inhibitors at all phases of development.

Take home message: Integrase inhibitors represent the newest therapeutic class available to treat HIV-1 infection. There are a variety of compounds either available in the clinic (RAL), advancing to Phase III trials (EVG), or in earlier phases of development. Taken together, this class offers new treatment options for the HIV-infected individual.     

Novel drugs in clinical development for hepatocellular carcinoma

Introduction: Sorafenib is the only systemic drug approved for the treatment of advanced hepatocellular carcinoma (HCC). Within recent years, several investigational agents mainly targeting angiogenesis failed in late-phase clinical development either due to toxicity or lack of benefit.

Areas covered: This review covers recent clinical data on systemic agents and ongoing trials in patients with advanced HCC.

Expert opinion: In unselected patients with advanced HCC, disappointing results have been reported from several large trials. However, in two subgroups encouraging results have been achieved. Treatment with the MET inhibitor tivantinib resulted in a substantial survival benefit in the subgroup of MET overexpressing tumors in a randomized Phase II trial. Furthermore, the vascular endothelial growth factor receptor 2 antibody ramucirumab resulted in improved overall survival in patients with baseline α-fetoprotein (AFP) ≥ 400 ng/ml in a Phase III trial. These two agents, and several others, will be further developed in HCC. Moreover, immunotherapeutics such as checkpoint inhibitors, programmed death receptor-1 blocking antibodies and oncolytic viruses are under investigation in advanced HCC.