Eligard®: Pharmacokinetics, Effect on Testosterone and PSA Levels and Tolerability

The Role of the PTEN Tumor Suppressor Gene and Its Anti-Angiogenic Activity in Melanoma and Other Cancers

Human malignant melanoma and other solid cancers are largely driven by the inactivation of tumor suppressor genes and angiogenesis. Conventional treatments for cancer (surgery, radiation therapy, and chemotherapy) are employed as first-line treatments for solid cancers but are often ineffective as monotherapies due to resistance and toxicity. Thus, targeted therapies, such as bevacizumab, which targets vascular endothelial growth factor, have been approved by the US Food and Drug Administration (FDA) as angiogenesis inhibitors. The downregulation of the tumor suppressor, phosphatase tensin homolog (PTEN), occurs in 30-40% of human malignant melanomas, thereby elucidating the importance of the upregulation of PTEN activity. Phosphatase tensin homolog (PTEN) is modulated at the transcriptional, translational, and post-translational levels and regulates key signaling pathways such as the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) and mitogen-activated protein kinase (MAPK) pathways, which also drive angiogenesis. This review discusses the inhibition of angiogenesis through the upregulation of PTEN and the inhibition of hypoxia-inducible factor 1 alpha (HIF-1-α) in human malignant melanoma, as no targeted therapies have been approved by the FDA for the inhibition of angiogenesis in human malignant melanoma. The emergence of nanocarrier formulations to enhance the pharmacokinetic profile of phytochemicals that upregulate PTEN activity and improve the upregulation of PTEN has also been discussed.

Long-acting injectable PLGA/PLA depots for leuprolide acetate: successful translation from bench to clinic

The excellent properties of polyesters combined with their ease of synthesis and modification enabled their wide use in the pharmaceutical industry. This has been translated into the approval of several injectable depots for clinical use. Long-acting depots for leuprolide acetate were among the first and most successful examples including Lupron Depot^® and ELIGARD^®. Studying these products is of great interest for researchers in both industry and academia. This will undoubtedly pave the road for the development of new as well as generic long-acting depots for a variety of drugs.

Recent Advances in Nanoparticle-Based Co-Delivery Systems for Cancer Therapy

Cancer therapies have advanced tremendously throughout the last decade, yet multiple factors still hinder the success of the different cancer therapeutics. The traditional therapeutic approach has been proven insufficient and lacking in the suppression of tumor growth. The simultaneous delivery of multiple small-molecule chemotherapeutic drugs and genes improves the effectiveness of each treatment, thus optimizing efficacy and improving synergistic effects. Nanomedicines integrating inorganic, lipid, and polymeric-based nanoparticles have been designed to regulate the spatiotemporal release of the encapsulated drugs. Multidrug-loaded nanocarriers are a potential strategy to fight cancer and the incorporation of co-delivery systems as a feasible treatment method has projected synergistic benefits and limited undesirable effects. Moreover, the development of co-delivery systems for maximum therapeutic impact necessitates better knowledge of the appropriate therapeutic agent ratio as well as the inherent heterogeneity of the cancer cells. Co-delivery systems can simplify clinical processes and increase patient quality of life, even though such systems are more difficult to prepare than single drug delivery systems. This review highlights the progress attained in the development and design of nano carrier-based co-delivery systems and discusses the limitations, challenges, and future perspectives in the design and fabrication of co-delivery systems.

Development of Pharmaceutical Nanomedicines: From the Bench to the Market

Nanotechnology plays a significant role in the field of medicine and in drug delivery, mainly due to the major limitations affecting the conventional pharmaceutical agents, and older formulations and delivery systems. The effect of nanotechnology on healthcare is already being felt, as various nanotechnology applications have been developed, and several nanotechnology-based medicines are now on the market. Across many parts of the world, nanotechnology draws increasing investment from public authorities and the private sector. Most conventional drug-delivery systems (CDDSs) have an immediate, high drug release after administration, leading to increased administration frequency. Thus, many studies have been carried out worldwide focusing on the development of pharmaceutical nanomedicines for translation into products manufactured by local pharmaceutical companies. Pharmaceutical nanomedicine products are projected to play a major role in the global pharmaceutical market and healthcare system. Our objectives were to examine the nanomedicines approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) in the global market, to briefly cover the challenges faced during their development, and to look at future perspectives. Additionally, the importance of nanotechnology in developing pharmaceutical products, the ideal properties of nanocarriers, the reasons behind the failure of some nanomedicines, and the important considerations in the development of nanomedicines will be discussed in brief.

Poly(3-Hydroxybutyrate)-Based Nanoparticles for Sorafenib and Doxorubicin Anticancer Drug Delivery

Dual drug-loaded nanotherapeutics can play an important role against the drug resistance and side effects of the single drugs. Doxorubicin and sorafenib were efficiently co-encapsulated by tailor-made poly([R,S]-3-hydroxybutyrate) (PHB) using an emulsion-solvent evaporation method. Subsequent poly(ethylene glycol) (PEG) conjugation onto nanoparticles was applied to make the nanocarriers stealth and to improve their drug release characteristics. Monodisperse PHB-sorafenib-doxorubicin nanoparticles had an average size of 199.3 nm, which was increased to 250.5 nm after PEGylation. The nanoparticle yield and encapsulation efficiencies of drugs decreased slightly in consequence of PEG conjugation. The drug release of the doxorubicin was beneficial, since it was liberated faster in a tumor-specific acidic environment than in blood plasma. The PEG attachment decelerated the release of both the doxorubicin and the sorafenib, however, the release of the latter drug remained still significantly faster with increased initial burst compared to doxorubicin. Nevertheless, the PEG-PHB copolymer showed more beneficial drug release kinetics in vitro in comparison with our recently developed PEGylated poly(lactic-co-glycolic acid) nanoparticles loaded with the same drugs.

Impact of CEA-targeting Nanoparticles for Drug Delivery in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common causes of cancer-related death in the world, mainly owing to distant metastasis events. Developing targeted strategies to treat and follow individuals in more developed stages is needed. The carcinoembryonic antigen (CEA) is a cell surface-overexpressed glycoprotein in most CRC patients, and the evaluation of its serum levels is recommended in the clinic. These reasons motivated the production of CEA-targeted nanotechnologies for monitorization of CRC progression, but only a few centers have reported their use for drug delivery. The cellular internalization of CEA-linked nanosystems occurs by the natural recycling of the CEA itself, enabling longer retention and sustained release of the cargo. The functionalization of nanoparticles with lower affinity ligands for CEA is possibly the best choice to avoid their binding to the soluble CEA. Here, we also highlight the use of nanoparticles made of poly(lactic-co-glycolic acid) (PLGA) polymer, a well known material, owing to its biocompatibility and low toxicity. This work offers support to the contribution of antibody fragment-functionalized nanoparticles as promising high affinity molecules to decorate nanosystems. The linkers and conjugation chemistries chosen for ligand-nanoparticle coupling will be addressed herein as an elements essential to the modulation of nanosystem features. This review, to our knowledge, is the first that focuses on CEA-targeted nanotechnologies to serve colorectal cancer therapy and monitorization.

Nanopharmaceuticals and nanomedicines currently on the market: challenges and opportunities

There has been a revolution in nanotechnology and nanomedicine. Since 1980, there has been a remarkable increase in approved nano-based pharmaceutical products. These novel nano-based systems can either be therapeutic agents themselves, or else act as vehicles to carry different active pharmaceutical agents into specific parts of the body. Currently marketed nanostructures include nanocrystals, liposomes and lipid nanoparticles, PEGylated polymeric nanodrugs, other polymers, protein-based nanoparticles and metal-based nanoparticles. A range of issues must be addressed in the development of these nanostructures. Ethics, market size, possibility of market failure, costs and commercial development, are some topics which are on the table to be discussed. After passing all the ethical and biological assessments, and satisfying the investors as to future profitability, only a handful of these nanoformulations, successfully obtained marketing approval. We survey the range of nanomedicines that have received regulatory approval and are marketed. We discuss ethics, costs, commercial development and possible market failure. We estimate the global nanomedicine market size and future growth. Our goal is to summarize the different approved nanoformulations on the market, and briefly cover the challenges and future outlook.

Nanomedicines: current status and future perspectives in aspect of drug delivery and pharmacokinetics

Nanomedicines have evolved into various forms including dendrimers, nanocrystals, emulsions, liposomes, solid lipid nanoparticles, micelles, and polymeric nanoparticles since their first launch in the market. Widely highlighted benefits of nanomedicines over conventional medicines include superior efficacy, safety, physicochemical properties, and pharmacokinetic/pharmacodynamic profiles of pharmaceutical ingredients. Especially, various kinetic characteristics of nanomedicines in body are further influenced by their formulations. This review provides an updated understanding of nanomedicines with respect to delivery and pharmacokinetics. It describes the process and advantages of the nanomedicines approved by FDA and EMA. New FDA and EMA guidelines will also be discussed. Based on the analysis of recent guidelines and approved nanomedicines, key issues in the future development of nanomedicines will be addressed.

Androgen deprivation therapy with Leuprolide acetate for treatment of advanced prostate cancer

INTRODUCTION

Hormone sensitive advanced prostate cancer (PCa) is an incurable disease that is treated with a variety of hormonal therapies targeting the androgen/androgen receptor signaling axis. For decades androgen deprivation therapy (ADT) by surgical or chemical castration is the gold standard for the treatment of advanced PCa. Areas covered: This review discusses the pharmacological features of Leuprolide, a luteinizing hormone-releasing hormone (LHRH) agonists/analog and the most commonly used drug in ADT. Expert opinion: Although Leuprolide has been on the market for more than 30 years it is still the leading option for ADT and serves as a basis for most multimodal therapy concepts. The fact that with the onset of castration-resistance in late stage metastatic disease, a prolongation of ADT in combination with a second line hormonal manipulation is recommended supports the importance of the compound for daily clinical practice.

Extended release, 6-month formulations of leuprolide acetate for the treatment of advanced prostate cancer: achieving testosterone levels below 20 ng/dl

INTRODUCTION

Luteinizing hormone-releasing hormone agonists such as leuprolide acetate (LA) are the most frequently utilized treatment of advanced prostate cancer as the regimen for achieving androgen deprivation therapy (ADT). The efficacy of LA is determined by extent of testosterone (T) suppression in prostate cancer patients. Although, the historical castrate T suppression target has been defined as < 50 ng/dl, this level may not be as low as required to deliver equivalent suppression as achieved by surgical castration. Recent studies have demonstrated that a T level as low as 20 ng/dl may produce improved clinical outcomes.

AREAS COVERED

LA is available in long-acting formulations that deliver active drug over the course of 1-6 months from a single-dose administration. The technologies utilized to provide sustained drug delivery differ: one mode of administration uses microspheres, which encapsulate the drug and are injected as a suspension intramuscularly; another mode of administration uses a liquid polymer that creates a single, solid depot after injection subcutaneously. This article will review the safety and efficacy of both 6-month LA formulations, as well as their impact in prostate cancer treatment.

EXPERT OPINION

As the understanding of optimal T castrate level evolves and may be refined pending new data from contemporaneous trials, achievement and maintenance of T levels well below 50 ng/dl may be important in evaluating potential differences in ADT regimens.

Multifunctional nanoparticles for use in theranostic applications

Theranostics is a promising field that combines therapeutics and diagnostics into single multifunctional formulations. This field is driven by advancements in nanoparticle systems capable of providing the necessary functionalities. By utilizing these powerful nanomedicines, the concept of personalized medicine can be realized by tailoring treatment strategies to the individual. This review gives a brief overview of the components of a theranostic system and the challenges that designing truly multifunctional nanoparticles present. Considerations when choosing a class of nanoparticle include the size, shape, charge, and surface chemistry, while classes of nanoparticles discussed are polymers, liposomes, dendrimers, and polymeric micelles. Targeting to disease states can be achieved either through passive or active targeting which uses specific ligands to target receptors that are overexpressed in tumors and common targeting elements are presented. To image the interactions with disease states, contrast agents are included in the nanoparticle formulation. Imaging options include optical imaging techniques, computed tomography, nuclear based, and magnetic resonance imaging. The interplay between all of these components needs to be carefully considered when designing a theranostic system.

Physical and biological considerations for the use of nonaqueous solvents in oral bioavailability enhancement

This review addresses the use of nonaqueous solvents as components of oral formulations in discovery and preclinical studies. Pharmacology, pharmacokinetic, and safety studies are frequently conducted with solution formulations that use a solvent to solubilize poorly aqueous soluble drugs. The physical chemical basis for solubilization and the precipitation of solubilized drug following administration both contribute to the utility of nonaqueous solvent solutions as oral vehicles. While many of these solvents are considered nontoxic, they are not completely inert biologically. The effects of common nonaqueous solvents on the structural integrity of the epithelia, the inherent permeability of and flux across the GI membrane, the activity of efflux and metabolic enzymes, and the effects on GI motility and GI transit times will be described through an examination of available literature. The practical relevance of these factors to the development of early formulations will be examined critically and suggestions made for the suitability of nonaqueous solvents for a variety of purposes.

[Time-course of plasma testosterone in patients with prostate cancer treated by endocrine therapy]

OBJECTIVE

To assess the time-course of plasma testosterone in patients with prostate cancer treated by endocrine therapy.

METHODS

A PubMed review of the literature on plasma testosterone and the various endocrine therapies for prostate cancer was performed.

RESULTS

The time-course of plasma testosterone varies according to the type of endocrine therapy. The effective castration level, classically considered to be 50 ng/dl, is currently tending to be replaced by 20 ng/dl. Following surgical castration, plasma testosterone reaches effective castration levels within several hours, while with LH-RH agonist therapy, plasma testosterone reaches its trough value after three to four weeks, and remains low for six months after stopping treatment. However, about 15% of patients treated with LH-RH agonists do not achieve effective castration levels. Plasma testosterone remains unchanged or even increases in response to anti-androgens. Plasma testosterone assay is of limited value in routine clinical practice in patients receiving endocrine therapy for prostate cancer, but should be performed in the case of elevation of PSA to ensure that the patient has achieved effective castration levels.

CONCLUSION

The correlation between plasma testosterone and progression of prostate cancer is unclear. Other studies are therefore necessary to define the value of plasma testosterone assay in patients treated for prostate cancer.

Pharmacotherapy for prostate cancer, with emphasis on hormonal treatments

For more than half a century, hormonal therapy has been one of the cornerstones of prostate cancer therapy. However, the position and timing of androgen deprivation therapy is continuously challenged. Nowadays, it is often combined with other types of treatment in a multi-modal approach, especially with radiation therapy. Besides the well-known luteinising hormone-releasing hormone agonists, several developments have been introduced (e.g., luteinising hormone-releasing hormone antagonists or improved depot formulations achieving a better pharmacokinetic slope and lower testosterone levels). Research developments include a better understanding of the different gonadotropin-releasing hormone isoforms, the ligand-independent transformation of the androgen receptor and androgen receptor overexpression in hormone-insensitive disease. Prostate cancer, previously thought to be chemotherapy insensitive, is now treated at the metastatic stage by taxane-based chemotherapies. The combination of hormonal therapy and chemotherapy is currently studied at various stages of the disease, as early as localised or locally advanced prostate cancer. It is very likely that, in the future, pharmacological treatment for prostate cancer will include combination therapies rather than monotherapies. The authors suggest an in-depth re-evaluation of the place of androgen deprivation therapy in prostate cancer.