Targeting miR-21 in glioma: a small RNA with big potential

Importance of the field: Glioma therapies have produced relatively small improvements over the past decade, highlighting an important need to identify novel ways to target this disease. Targeted therapies against single activated protein kinases have proven effective in some cancers including gastrointestinal stromal cancer and colon cancer, but not yet in gliomas where multiple pathways and targets may be involved. MicroRNAs are emerging as key regulators of multiple pathways involved in cancer development and progression and may become the next targeted therapies in glioma.

Areas covered in this review: This review covers the basics of microRNA biology and specifically focuses on the roles of miR-21 in glioma and its potential as target for glioma therapy.

What the reader will gain: This review will provide the reader with an in depth understanding of how miR-21 functions in glioma. We also review the current state of studies designed to specifically target miR-21 as a potential future therapeutic.

Take home message: Identifying novel targets for the treatment of glioma is critical for advancing the current state of the field. MicroRNAs provide a novel target; and in glioma, targeting miR-21 may have broad consequences for the tumor that make it an attractive potential therapeutic.     

Pharmacotherapy of regional melanoma therapy

Importance of the field: In-transit melanoma metastases develop within regional dermal and subdermal lymphatics before reaching the regional lymph nodes. The prognosis is poor and comparable to multiple nodal metastases. Isolated limb infusion (ILI) or perfusion (ILP) are effective treatments for unresectable, in-transit melanoma, with response rates reaching 95%. Although ILI and ILP are more effective than systemic therapy, most patients will recur, thus highlighting the need for newer strategies to improve durable response rates.

Areas covered in this review: We review historical and current literature from 1958 to 2009 regarding regional therapy for melanoma, with focus on the ILI and ILP techniques, pharmacokinetics and resistance mechanisms of melphalan. Alternative therapies, adjunct strategies and new targeted therapies aimed at improving response rates and long-term remission are also discussed.

What the reader will gain: The reader will gain a comprehensive review on regional pharmacotherapy for melanoma, including alternative therapies, adjunct strategies and new targeted therapies.

Take home message: Regional chemotherapy is a viable, evolving treatment for patients with in-transit melanoma and a springboard for ongoing research aimed at improving therapies for malignant melanoma.     

‘Big data’ approaches for novel anti-cancer drug discovery

Introduction: The development of improved cancer therapies is frequently cited as an urgent unmet medical need. Recent advances in platform technologies and the increasing availability of biological ‘big data’ are providing an unparalleled opportunity to systematically identify the key genes and pathways involved in tumorigenesis. The discoveries made using these new technologies may lead to novel therapeutic interventions.

Areas covered: The authors discuss the current approaches that use ‘big data’ to identify cancer drivers. These approaches include the analysis of genomic sequencing data, pathway data, multi-platform data, identifying genetic interactions such as synthetic lethality and using cell line data. They review how big data is being used to identify novel drug targets. The authors then provide an overview of the available data repositories and tools being used at the forefront of cancer drug discovery.

Expert opinion: Targeted therapies based on the genomic events driving the tumour will eventually inform treatment protocols. However, using a tailored approach to treat all tumour patients may require developing a large repertoire of targeted drugs.     

The use of single chain Fv as targeting agents for immunoliposomes: an update on immunoliposomal drugs for cancer treatment

Importance of the field: Targeted liposomal drugs represent the next evolution of liposomal drug delivery in cancer treatment. In various preclinical cancer models, antibody-targeted PEGylated liposomal drugs have demonstrated superior therapeutic effects over their non-targeted counterparts. Single chain Fv (scFv) has gained popularity in recent years as the targeting agent of choice over traditional targeting agents such as monoclonal antibodies (mAb) and antibody fragments (e.g., Fab′).

Areas covered in this review: This review is focused mainly on advances in scFv-targeted liposomal drug delivery for the treatment of cancers, based on a survey of the recent literature, and on experiments done in a murine model of human B-lymphoma, using anti-CD19 targeted liposomes targeted with whole mAb, Fab′ fragments and scFv fragments.

What the reader will gain: This review examines the recent advances in PEGylated immunoliposomal drug delivery, focusing on scFv fragments as targeting agents, in comparison with Fab′ and mAb.

Take home message: For clinical development, scFv are potentially preferred targeting agents for PEGylated liposomes over mAb and Fab′, owing to factors such as decreased immunogenicity, and pharmacokinetics/biodistribution profiles that are similar to non-targeted PEGylated (Stealth^®) liposomes.     

Safety profile of new anticancer drugs

Importance of the field: The development of targeted anticancer therapies stems from advances in molecular biology. New agents range from antibodies that form complexes with antigens on the surface of the cancer cell to small molecules that have been engineered to block key enzymatic reactions. The interaction of the antibody or drug with its target inhibits key pathways involved in cell proliferation or metastasis, or activates pathways leading to cell death. Such pathways constitute ideal pharmacological targets. Clinical benefits from these novel therapeutic strategies are striking for patients with metastatic diseases.

Areas covered: This review analyses the main toxicities among most common targeted therapies that have been approved by the FDA or European Medicines Agency for their clinical utilisation in solid tumours treatment.

What the reader will gain: Here, the main toxicity and safety data among new anticancer targeted therapies are described. Data are organised through the pathways targeted by the drugs.

Take home message: The emergence of new targeted anticancer therapies promises more efficient and less toxic therapies. Generally, they are well tolerated, toxicities are commonly mild to moderate and can be handled rapidly. However, if most of these adverse events are manageable, life threatening and fatal complications can still occur.     

Pharmacotherapy of neuroblastoma

Importance of the field: Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extracranial solid tumor of early life. High risk disease in older children remains a therapeutic challenge, despite high-intensity therapy with correspondingly significant short- and long-term toxicities.

Areas covered in this review: We have reviewed therapy for neuroblastoma over the last three decades. This includes cytotoxic chemotherapy, immunotherapy, radionuclides, antiangiogenic compounds, and molecularly targeted agents. We provide a perspective on the incorporation of these drugs into therapy for neuroblastoma.

What the reader will gain: The reader will gain a better understanding of these novel agents and their targets in neuroblastoma. The reader will also gain insight into the need to define through sequential, carefully designed clinical trials, the roles and toxicities of these therapies, especially if the combination of targeted and conventional cytotoxic agents is used.

Take home message: Advanced-stage neuroblastoma in older infants and children remains a disease that is difficult to cure. New, targeted agents may improve both the therapeutic index and the outcome, but are, for the most part, in early development and present a challenge for clinical trial design given both the rarity of this disease and its responsiveness (albeit incomplete) to currently used cytotoxic agents.     

Emerging drugs for high-grade osteosarcoma

Importance of the field: Osteosarcoma (OS) is the most common primary malignant bone tumour in children and adolescents. This review focuses on the most promising therapeutic markers and drugs which may potentially be considered for innovative high-grade OS treatments.

Areas covered in this review: The list of drugs and compounds reviewed has been generated by taking into account those which target markers of potential clinical interest for high-grade OS and have been included in Phase I, II or III clinical trials. The literature search covers the last 40 years, starting from the first OS chemotherapy reports of the early 1970s. Particular relevance was given to reports and reviews on new targeted therapies of possible clinical usefulness for high-grade OS.

What the reader will gain: This review gives an updated overview of novel therapeutic approaches which have been or are going to be evaluated in Phase I/II/III clinical studies for high-grade OS.

Take home message: On the basis of the information that has emerged so far, it can be predicted that in the next 5 – 10 years, new agents to be included in innovative treatment strategies for selected subgroups of high-grade OS patients may become available.     

Safety and efficacy of over- the-counter cough and cold medicines for use in children

Importance of the field: Over-the-counter (OTC) cough and cold medications have been used widely for years and continue to be a preferred choice for temporary relief of symptoms of upper respiratory tract infections in children. These medications are being placed under extraordinary scrutiny in the pediatric population due to the lack of conclusive evidence about their therapeutic efficacy and increased reports of associations with serious adverse events and even mortality.

Areas covered in this review: A PubMed search was conducted to identify articles published up to August 2009 describing the efficacy and safety of OTC cough and cold medications in children. The objective was to provide an overview of the relevant literature and regulatory history and to comment on the available data on this important topic.

What the reader will gain: The paper provides a detailed up-to-date review of the key efficacy and safety studies published on the subject. In addition, the reader is presented with an overview of the regulatory history and recent developments surrounding the use of OTC cough and cold medications in children in the US.

Take home message: This review confirms the lack of efficacy of OTC cough and cold products in children and reaffirms that although the overall incidence of related serious adverse events is low, such events continue to occur. The conclusions in this paper support a recommendation that OTC cough and cold medications should not be given to infants and very young children. Furthermore, additional research is needed to evaluate the safety and efficacy of these medicines in the broader pediatric population.     

Molecular targeted therapy of advanced hepatocellular carcinoma beyond sorafenib

Importance of the field: With the recent advances in the knowledge of molecular biology of hepatocellular carcinoma (HCC), there have been encouraging developments in targeted therapy for advanced HCC.

Areas covered in this review: This review discusses the development of targeted therapy for advanced HCC patient since 2006. Among the newly identified targets, promising results have been shown in targeting the anti-angiogenic pathway. Pure anti-angiogenic agents such as bevacizumab and PTK 787 demonstrate modest activity in treating patients with advanced HCC. Sorafenib, a multi-targeted tyrosine kinase inhibitor with both anti-angiogenic and anti-proliferative effects, has been shown to prolong the overall survival of patients with advanced HCC in two Phase III randomized trials. Like sorafenib, other anti-angiogenic multi-targeted tyrosine kinase inhibitors, such as sunitinib, pazopanib, brivanib and linifanib, also show promising activity in various stages of clinical trials. Other on-going early-phase studies are exploring the activities of drugs targeting novel pathways, such as PI3K/AKT/m TOR, hepatocyte growth factor/mesenchymal epithelial transition factor and insulin-like growth factor.

What the reader will gain: After reading this review, the reader should have an in-depth understanding of the latest developments in the molecular targeted therapy of advanced HCC.

Take home message: The development of sorafenib in the treatment of advanced HCC proves the concept that molecular targeted therapies, especially anti-angiogenic agents, play a pivotal role in the treatment of this otherwise chemoresistant neoplasm. Future progress depends on further unraveling more molecular mechanisms of HCC for therapeutic intervention.     

Targeting IL-23 in human diseases

Importance of the field: IL-23 is one of the most intriguing cytokine for its many immunological functions, which are the basis of its important role in host defense but also of its possible contribution to the pathogenesis of several diseases.

Areas covered in this review: The literature and patents about IL-23 pathway and their targeting in therapeutic potential applications. Findings published within the last 5 years receive particular attention.

What the reader will gain: An overview of the emerging role of IL-23 in physiological and pathological conditions and a review of the different approaches (IL-23 pathway-based) currently used for autoimmune diseases and cancer therapies and the results obtained both in preclinical models and in clinical trials.

Take home message: Inhibition/targeting of IL-23 may be a good and novel therapeutic strategy, especially in the treatment of diseases like psoriasis, for which current treatments show more pronounced side effects than those of IL-23-blocking and employed as part of specific patient-tailored therapies in inflammatory bowel diseases.     

Taking aim at Mer and Axl receptor tyrosine kinases as novel therapeutic targets in solid tumors

Importance of the field: Axl and/or Mer expression correlates with poor prognosis in several cancers. Until recently, the role of these receptor tyrosine kinases (RTKs) in development and progression of cancer remained unexplained. Studies demonstrating that Axl and Mer contribute to cell survival, migration, invasion, metastasis and chemosensitivity justify further investigation of Axl and Mer as novel therapeutic targets in cancer.

Areas covered in this review: Axl and Mer signaling pathways in cancer cells are summarized and evidence validating these RTKs as therapeutic targets in glioblastoma multiforme, NSCLC, and breast cancer is examined. A discussion of Axl and/or Mer inhibitors in development is provided.

What the reader will gain: Potential toxicities associated with Axl or Mer inhibition are addressed. We propose that the probable action of Mer and Axl inhibitors on cells within the tumor microenvironment will provide a therapeutic opportunity to target both tumor cells and the stromal components that facilitate disease progression.

Take home message: Axl and Mer mediate multiple oncogenic phenotypes and activation of these RTKs constitutes a mechanism of chemoresistance in a variety of solid tumors. Targeted inhibition of these RTKs may be effective as anti-tumor and/or anti-metastatic therapy, particularly if combined with standard cytotoxic therapies.     

Towards a targeted multi-drug delivery approach to improve therapeutic efficacy in breast cancer

Importance of the field: Significant improvements in breast cancer treatments have resulted in a significant decrease in mortality. However, current breast cancer therapies, for example, chemotherapy, often result in high toxicity and nonspecific side effects. Other treatments, such as hormonal and antiangiogenic therapies, often have low treatment efficacy if used alone. In addition, acquired drug resistance decreases further the treatment efficacy of these therapies. Intra-tumor heterogeneity of the tumor tissue may be a major reason for the low treatment efficacy and the development of chemoresistance. Therefore, targeted multi-drug therapy is a valuable option for addressing the multiple mechanisms that may be responsible for reduced efficacy of current therapies.

Areas covered in this review: In this article, different classes of drugs for treating breast cancer, the possible reasons for the drug resistance in breast cancer, as well as different targeted drug delivery systems are summarized. The current targeting strategies used in cancer treatment are discussed.

What the reader will gain: This article considers the current state of breast cancer therapy and the possible future directions in targeted multi-drug delivery for treating breast cancer.

Take home message: A better understanding of tumor biology and physiological responses to nanoparticles, as well as advanced nanoparticle design, are needed to improve the therapeutic outcomes for treating breast cancer using nanoparticle-based targeted drug delivery systems. Moreover, selective delivery of multi-drugs to tumor tissue using targeted drug delivery systems may reduce systemic toxicity further, overcome drug resistances, and improve therapeutic efficacy in treating breast cancer.     

Zinc oxide nanoparticles for selective destruction of tumor cells and potential for drug delivery applications

Importance of the field: Metal oxide nanoparticles, including zinc oxide, are versatile platforms for biomedical applications and therapeutic intervention. There is an urgent need to develop new classes of anticancer agents, and recent studies demonstrate that ZnO nanomaterials hold considerable promise.

Areas covered in this review: This review analyzes the biomedical applications of metal oxide and ZnO nanomaterials under development at the experimental, preclinical and clinical levels. A discussion regarding the advantages, approaches and limitations surrounding the use of metal oxide nanoparticles for cancer applications and drug delivery is presented. The scope of this article is focused on ZnO, and other metal oxide nanomaterial systems, and their proposed mechanisms of cytotoxic action, as well as current approaches to improve their targeting and cytotoxicity against cancer cells.

What the reader will gain: This review aims to give an overview of ZnO nanomaterials in biomedical applications.

Take home message: Through a better understanding of the mechanisms of action and cellular consequences resulting from nanoparticles interactions with cells, the inherent toxicity and selectivity of ZnO nanoparticles against cancer may be improved further to make them attractive new anticancer agents.     

Protein–protein interaction modulator drug discovery: past efforts and future opportunities using a rich source of low- and high-throughput screening assays

Introduction: Historically, small-molecule drug discovery projects have largely focused on the G-protein-coupled receptor, ion-channel and enzyme target classes. More recently, there have been successes demonstrating that protein–protein interactions (PPIs) can be targeted by small-molecules and that this strategy has the potential to provide appropriate specificity and selectivity. However, a disadvantage is that compounds that modulate PPIs are often associated with relatively weak affinities as the targeted interaction surfaces are often relatively large. Moreover, from a small-molecule screening perspective, a large proportion of the initial screening Hits are often false positives and these need to be identified and excluded in order to focus on genuine modulators of the PPI being investigated.

Areas covered: The authors review previous efforts on PPI modulator drug discovery. Furthermore, they review assays that can be employed in small-molecule screening and/or Hit validation. The PPI assays are categorized as: i) low-throughput target-based biochemical assays, which are primarily employed for Hit validation at the post-screening stage; ii) high-throughput target-based biochemical assays that are suitable for screening campaigns; and iii) cell-based assays, which are suitable for high-throughput screening campaigns and/or Hit validation.

Expert opinion: Modulating the interaction of PPIs offers the potential to develop novel drugs to treat a wide range of diseases. New assay technologies are continually being developed and it is anticipated that these will be able to be directly used for small-molecule screening campaigns in the future.     

Antagonist molecules in the treatment of angina

Introduction: Management of chronic angina has evolved dramatically in the last few decades with several options for pharmacotherapy outlined in various evidence-based guidelines.

Areas covered: There is a growing list of drugs that are currently being investigated for treatment of chronic angina. These also include several herbal medications, which are now being scientifically evaluated as potential alternative or even adjunctive therapy for angina. Gene- and cell-based therapies have opened yet another avenue for management of chronic refractory angina in ‘no-option' patients who are not candidates for either percutaneous or surgical revascularization and are on optimal medical therapy. An extensive review of literature using PUBMED, Cochrane database, clinical trial databases of the USA and European Union was done and summarized in this review. This review will attempt to discuss the traditional as well as novel therapeutic agents for angina.

Expert opinion: Several pharmacological and non-pharmacological therapeutic options are now available for treatment and management of chronic refractory angina. Renewed interest in traditional therapies and cell- and gene-based modalities with targeted drug delivery systems will open the doors for personalized therapy for patients with chronic refractory angina.     

How can high-throughput screening deliver drugs to treat atherosclerosis?

Importance of the field: Atherosclerosis is a progressive disease that is characterized by the accumulation of lipid-rich plaques within the artery walls. Despite the past 3 decades witnessing the most significant advances in the pharmacotherapy of atherosclerosis with statins, atherosclerosis is still one of the leading causes of mortality in industrialized and developing nations. The applications of high-throughput screening (HTS) have retrieved hits and lead compounds which may be further developed to new promising therapeutics to achieve more effective reductions in the risk of cardiovascular morbidity and mortality.

Areas covered in this review: The review provides a summary of potential drug targets other than HMG-CoA reductase (primary target of statins) and their application in biochemical or cell-based HTS assays used by pharmaceutical companies and academic laboratories for anti-atherosclerotic drug discovery.

What the reader will gain: The reader will gain an overview of the HTS strategies currently used in the development of anti-atherosclerotic agents. The reader is also provided with some abortive examples in anti-atherosclerotic drug discovery as well as the associated limitations and challenges of the process that HTS delivers new drugs to treat atherosclerosis.

Take home message: HTS can assist in the efficient discovery of new drugs towards the potential targets involved in the progress of atherosclerosis.     

Receptor-mediated tumor targeting based on peptide hormones

Importance of the field: Tumor targeting with peptides is based on the discovery that receptors for many regulatory peptides are overexpressed in tumor cells, compared with their expression in normal tissues. Consequently, these peptides and their analogues can be used as carriers/targeting moieties for the preparation of diagnostic and therapeutic agents that have increased selectivity and decreased peripheral toxicity.

Areas covered in this review: Here an overview is given of the most relevant gonadotropin-releasing hormone (GnRH) and somatostatin derivatives, as well as of their applications in cancer diagnosis and therapy. For this purpose, recently published data in these areas (mostly articles published from 2000 to 2009) were reviewed.

What the reader will gain: In contrast to other regulatory peptides that stimulate the tumor growth, GnRH and somatostatin derivatives have inhibitory effect; therefore, they were used primarily for the preparation of various conjugates to be used in targeted chemotherapy, targeted radiotherapy, photodynamic therapy, boron neutron capture therapy and cancer diagnosis. Some of these conjugates have already found clinical applications, whereas others are now in preclinical and clinical trials.

Take home message: Tumor targeting with hormone peptides provides a basis for the development of new diagnostic and therapeutic approaches for cancer.     

Topical delivery for the treatment of psoriasis

Importance of the field: Psoriasis is one of the most common human skin diseases. Topical therapy forms the cornerstone in the management of mild-to-moderate psoriasis. Topical therapies are also used as adjunctive to systemic therapy in moderate and severe forms of the disease.

Areas covered in this review: In this review, an overview of psoriasis pathogenesis, new topical medications for psoriasis, new targets and molecules, combination topical therapies and combination of topical and phototherapy is provided. Over the past decade several efficacious and acceptable treatment options have emerged from the age-old therapies. The development of sophisticated formulation options has led to an enhancement in the rate and extent of drug delivery across the skin, increasing therapeutic value and improving patient compliance.

What the reader will gain: Readers will learn about monotherapy and combination topical products as well as new topical drug delivery technology to achieve optimal clinical outcomes. This review will highlight the need to generate more dermal pharmacokinetic data for better understanding of the impact of formulation change on skin pharmacokinetics to help design improved topical drug delivery systems.

Take home message: New topical formulations have the potential to achieve better efficacy with improved safety profile.     

Patented inhibitors of p53–Mdm2 interaction (2006 – 2008)

Importance of the field: Induction of apoptosis by reactivation of p53 in cancer cells is an emerging therapeutic concept for the treatment of cancer. The discovery and design of novel small molecules that block the p53–Mdm2 protein interaction, thereby activating p53, has provided interesting drug candidates that have currently entered clinical trials or are at the preclinical development stage.

Areas covered in this review: A selection of the interesting patents focusing on small molecule inhibitors of the p53–Mdm2 interaction, recorded from 2006 until 2009, is presented together with a review of the related structural chemistry space.

What the reader will gain: Readers will rapidly gain an overview of the majority of patented scaffolds of small molecule inhibitors of the p53–Mdm2 protein–protein interaction and learn about current limitations and properties of these compounds.

Take home message: The discovery p53–Mdm2 protein–protein interaction inhibitors have delivered new potential options for a targeted cancer therapy with drug-like, non-toxic small molecules. If successful, this approach could gain considerably more attention in the pharmaceutical industry by targeting a variety of validated intracellular protein–protein interactions.     

Advances in chemotherapy in advanced non-small-cell lung cancer

Importance of the field: Lung cancer is the most common cancer in the world today, in terms of both incidence and mortality. Non-small-cell lung cancer (NSCLC) accounts for about 85% of all lung cancers diagnosis, and the majority of people diagnosed with NSCLC have advanced disease.

Areas covered in this review: In this review the main advances achieved in the medical treatment of advanced NSCLC are discussed, regarding both targeted therapies and chemotherapy. Among targeted therapies, recent data on the anti-vascular endothelial growth factor (VEGF) monoclonal antibody bevacizumab and the epidermal growth factor receptor tyrosyne kinase inhibitors (EGFR-TKIs) gefitinib and erlotinib are described. Among chemotherapeutic agents, the role of pemetrexed is discussed.

What the reader will gain: The reader will gain up-to-date information on the main advances, achieved in the last 3 years in the medical treatment of advanced NSCLC.

Take home message: Some recent advances have changed the face of the first-line chemotherapy of advanced NSCLC, giving physicians more options to tailor choice in this challenging setting.