Liposomal approach towards the development of a longer-acting factor VIII

A Transversal Approach Combining In Silico, In Vitro and In Vivo Models to Describe the Metabolism of the Receptor Interacting Protein 1 Kinase Inhibitor Sibiriline

Sibiriline is a novel drug inhibiting receptor-interacting protein 1 kinase (RIPK1) and necroptosis, a regulated form of cell death involved in several disease models. In this study, we aimed to investigate the metabolic fate of sibiriline in a cross-sectional manner using an in silico prediction, coupled with in vitro and in vivo experiments. In silico predictions were performed using GLORYx and Biotransformer 3.0 freeware; in vitro incubation was performed on differentiated human HepaRG cells, and in vivo experiments including a pharmacokinetic study were performed on mice treated with sibiriline. HepaRG culture supernatants and mice plasma samples were analyzed with ultra-high-performance liquid chromatography, coupled with tandem mass spectrometry (LC-HRMS/MS). The molecular networking bioinformatics tool applied to LC-HRMS/MS data allowed us to visualize the sibiriline metabolism kinetics. Overall, 14 metabolites, mostly produced by Phase II transformations (glucuronidation and sulfation) were identified. These data provide initial reassurance regarding the toxicology of this new RIPK1 inhibitor, although further studies are required.

Molecular approaches for improved clotting factors for hemophilia

Hemophilia is caused by a functional deficiency of one of the coagulation proteins. Therapy for no other group of genetic diseases has seen the progress that has been made for hemophilia over the past 40 years, from a life expectancy in 1970 of ∼20 years for a boy born with severe hemophilia to essentially a normal life expectancy in 2013 with current prophylaxis therapy. However, these therapies are expensive and require IV infusions 3 to 4 times each week. These are exciting times for hemophilia because several new technologies that promise extended half-lives for factor products, with potential for improvements in quality of life for persons with hemophilia, are in late-phase clinical development.

The future of hemostasis management

We are in the midst of an unprecedented period for the development of new therapeutic products to treat patients with bleeding diseases. While current hemostatic treatments are already very effective and safe, new agents to enhance convenience and further improve both short- and long-term efficacy of treatment are under development. Some of these products have already reached the clinic for early phase trials, and others will be available shortly. The strategies being evaluated for hemostatic enhancement range from gene and nucleic acid-based approaches, to the development of complex, naturally occurring molecules such as the non-anticoagulant polysaccharide, fucoidan. There is every likelihood that combinations of these treatment approaches will further improve the quality of bleeding disease management over the next 5 years and beyond.

Molecular approaches for improved clotting factors for hemophilia

Hemophilia is caused by a functional deficiency of one of the coagulation proteins. Therapy for no other group of genetic diseases has seen the progress that has been made for hemophilia over the past 40 years, from a life expectancy in 1970 of ∼20 years for a boy born with severe hemophilia to essentially a normal life expectancy in 2013 with current prophylaxis therapy. However, these therapies are expensive and require IV infusions 3 to 4 times each week. These are exciting times for hemophilia because several new technologies that promise extended half-lives for factor products, with potential for improvements in quality of life for persons with hemophilia, are in late-phase clinical development.

Long-lasting recombinant factor VIII proteins for hemophilia A

In the past 50 years, the lifespan of an individual affected with severe hemophilia A has increased from a mere 20 years to near that of the general unaffected population. These advances are the result of and parallel advances in the development and manufacture of replacement therapies. We are now poised to witness further technologic leaps with the development of longer-lasting replacement therapies, some of which are likely to be approved for market shortly. Prophylactic therapy is currently the standard of care for young children with severe hemophilia A, yet requires frequent infusion to achieve optimal results. Longer-lasting products will transform our ability to deliver prophylaxis, especially in very young children. Longer-lasting replacement therapies will require changes to our current treatment plans including those for acute bleeding, prophylaxis, surgical interventions, and even perhaps immunotolerance induction. Ongoing observation will be required to determine the full clinical impact of this new class of products.

Hemophilia: New Protein Therapeutics

Therapeutic advances for patients with hemophilia have resulted in reduced mortality, improved joint outcomes, safety from blood-transmitted pathogens, improved quality of life, and a normalized life span in the developed world. The production of recombinant coagulation factors has increased the worldwide capacity for replacement therapy and facilitated aggressive prophylactic therapy. However, this has come at significant cost, and barriers remain to broad application of prophylaxis. Recombinant DNA technology remains a promising platform to develop novel hemophilia therapeutics with improved functional properties to try to overcome some of these remaining barriers. Bioengineering strategies have produced novel therapeutics with increased production efficiency, increased potency and resistance to inactivation, prolonged plasma half-lives, and reduced immunogenicity. Alternative nonbiologic therapies may lead to new treatment paradigms. The current pipeline of new technologies and products is promising and growing with several agents already advancing from preclinical to clinical trials.

The use of PEGylated liposomes in the development of drug delivery applications for the treatment of hemophilia

Hemophilia A is a rare X-linked bleeding disorder caused by lack or dysfunction of coagulation factor VIII (FVIII). Hemophilia A is treated with replacement therapy, but frequent injections of the missing FVIII often lead to the formation of inhibitory antibodies. Patients who develop high levels of inhibitors must be treated with bypassing agents such as activated FVII (FVIIa). Both FVIII and FVIIa have short half-lives and require multiple injections. Long-acting forms of these proteins would therefore reduce the frequency of injections, improve patient compliance and reduce complications. In this article we present a new platform technology that produces long-acting forms of FVIII and FVIIa and improves the efficacy of hemophilia treatment. This technology is based on the binding of proteins/peptides to the outer surface of PEGylated liposomes (PEGLip). Binding is dependent on an amino acid consensus sequence within the proteins and is highly specific. At the same time, binding is non-covalent and does not require any modification of the therapeutic agent or its production process. Association of proteins with PEGLip results in substantial enhancements in their pharmacodynamic properties following administration. These improvements seem to arise from the association of formulated proteins with platelets prior to induction of coagulation.

Delivery of therapeutic proteins

The safety and efficacy of protein therapeutics are limited by three interrelated pharmaceutical issues, in vitro and in vivo instability, immunogenicity and shorter half-lives. Novel drug modifications for overcoming these issues are under investigation and include covalent attachment of poly(ethylene glycol) (PEG), polysialic acid, or glycolic acid, as well as developing new formulations containing nanoparticulate or colloidal systems (e.g., liposomes, polymeric microspheres, polymeric nanoparticles). Such strategies have the potential to develop as next generation protein therapeutics. This review includes a general discussion on these delivery approaches.

Gene therapy for haemophilia...yes, but...with non-viral vectors?

High-purity plasma-derived and recombinant factors are currently safe and efficient treatment for haemophilia. The mid-term future of haemophilia treatment will involve the use of modified recombinant factors to achieve advantages such as decreased immunogenicity in inhibitor formation and enhanced efficacy as a result of their longer half-life. In the long-term, gene therapy and cell therapy strategies will have to be considered. Achievements in cell therapy to date have been using embryonic stem cells and hepatic sinusoidal endothelial cells. Current gene therapy strategies for haemophilia are based on gene transfer using adeno-associated viruses and non-viral vectors. Gene therapy for haemophilia is justified because it is a chronic disease and because a very regular factor infusion is required that may involve fatal risks and because it is very expensive. Haemophilia is a very good candidate for use of gene therapy protocols because it is a monogenic disease, and even low expression is able to achieve reversion from a severe to a moderate phenotype. The current trends in haemophilia using adeno-associated viral vectors are safe but also involve immunogenicity problems. The other alternatives are non-viral vectors. There have been in recent years relevant advances in non-viral transfection that raise hope for considering this possibility. Several research groups are opting for this experimental alternative. An expression over 5%, representing a moderate phenotype, for a few months with a high safety, regarding vector, transfected cells, and implantation procedure, would already be a great success. This may represent an intermediate protocol in which the expression levels and times obtained are lower and shorter respectively as compared to viral vectors, but which provide a potential greater patient safety. This may more readily win acceptance among both patients and haematologists because fatal events in the past due to HIV/HCV infection may constrain the implementation of viruses as vectors.

Enhanced efficacy of recombinant FVIII in noncovalent complex with PEGylated liposome in hemophilia A mice

Recombinant FVIII formulated in PEG-ylated liposomes (rFVIII-PEG-Lip) was reported to increase the bleed-free days from 7 to 13 days (at 35 IU/kg rFVIII) in severe hemophilia A patients. To understand the underlying mechanism, we sought to recapitulate its efficacy in hemophilia A mice. Animals treated with rFVIII-PEG-Lip achieved approximately 30% higher survival relative to rFVIII after tail vein transection inflicted 24 hours after dosing. The efficacy of rFVIII-PEG-Lip represents an approximately 2.5-fold higher "apparent" FVIII activity, which is not accounted for by its modestly increased (13%) half-life. The enhanced efficacy requires complex formation between rFVIII and PEG-Lip before the administration. Furthermore, PEG-Lip associates with the majority of platelets and monocytes in vivo, and results in increased P-selectin surface expression on platelets in response to collagen. Rotational thromboelastometry (ROTEM) analysis of whole blood from rFVIII-PEG-Lip-treated animals at 5 minutes up to 72 hours after dosing recapitulated the 2- to 3-fold higher apparent FVIII activity. The enhanced procoagulant activity is fully retained in plasma unless microparticles are removed by ultracentrifugation. Taken together, the efficacy of rFVIII-PEG-Lip is mediated mainly by its sensitization of platelets and the generation of procoagulant microparticles that may express sustained high-affinity receptors for FVIII.

Enhancement of haemostatic efficacy of plasma-derived FVIII by formulation with PEGylated liposomes

We have shown previously that PEGylated liposomes (PEGLip) bind recombinant FVIII (rFVIII) with high affinity and specificity. This binding resulted in a significant extension of the biological activity of rFVIII as demonstrated in animal models and in clinical trials. In the present study we found that PEGLip bind plasma-derived factor VIII (pdFVIII). PEGLip binding did not affect potency or stability in vitro and did not alter levels of FVIII activity in vivo immediately after injection. However, formulation of pdFVIII with PEGLip led to several important improvements. Twenty-four and 30 hours after injection, FVIII activity levels were significantly higher in haemophilic mice injected with PEGLip-pdFVIII than in mice injected with standard pdFVIII. Half life, area under the curve and mean residence time were increased while clearance was decreased. In vivo efficacy was evaluated in a tail vein transection assay performed in haemophilic mice. Prophylactic treatment with PEGLip-pdFVIII was much more effective in prolonging survival in this assay than similar treatment with standard pdFVIII. These results suggest that formulation of pdFVIII with PEGLip has the potential to improve patient care by prolonging the biological efficacy of pdFVIII and reducing the frequency of FVIII infusions.

Recombinant factor VIII in the management of hemophilia A: current use and future promise

Hemophilia A is a rare inherited bleeding disorder due to mutation of the gene that encodes the coagulation protein factor VIII. Historically, prior to the availability of treatment with factor VIII preparations, most boys died from uncontrolled bleeding, either spontaneous bleeding or after injury, before reaching 20 years of age. One of the most impressive triumphs of modern medicine is that with current recombinant factor VIII replacement therapy, a boy born in the 21st century with severe hemophilia A can anticipate a normal life expectancy with essentially no permanent complications from bleeding. For severe hemophilia A, current optimal treatment should have two goals: first, to provide sufficient factor VIII to prevent spontaneous bleeding, and second, to provide sufficient factor VIII to have normal coagulation function after any trauma. However, the replacement therapy requires tremendous resources for effective use, and remains extraordinarily expensive. Thus there are opportunities for further advances in therapy for hemophilia A. Two major concerns continue to trouble current optimal treatment approaches: some patients will develop neutralizing antibodies during the first 50 infusions of therapeutic factor VIII, and second, to administer therapeutic factor VIII every other day in young boys often requires placement of a central venous access device, and such use carries the life-threatening risks of infection and thrombosis. Because of the effectiveness of current therapy, any new developments in treatment will require significant concerns for safety, both immediate and in the long term. A number of research groups seek to prolong the biological efficacy of infused recombinant factor VIII. Currently, one such promising development is in the advanced stages of clinical trial. The goals will be to improve further the quality of life of an individual with severe hemophilia A, and to reduce the burden of current treatment strategies on families and medical resources. Hopefully, the hemophilia community will continue to participate actively in the clinical trials needed to address these new challenges.

Binding of proteins to PEGylated liposomes and improvement of G-CSF efficacy in mobilization of hematopoietic stem cells

We have previously shown that formulation of coagulation factor VIII and activated factor VII with PEGylated liposomes (PEGLip) results in an extension of circulation time and an increase in hemostatic efficacy. Here we identified additional proteins that associate with PEGLip, including granulocyte colony-stimulating factor (G-CSF). Surface plasmon resonance analyses indicated that G-CSF bound noncovalently but with high affinity and specificity to PEGLip. A pharmacokinetic study in mice demonstrated that PEGLip formulation of G-CSF extended its circulation time and resulted in higher G-CSF levels several hours after both subcutaneous and intravenous injection. PEGLip-formulated G-CSF had a significantly improved efficacy in the mobilization of hematopoietic stem cells (HSC) from the bone marrow to the peripheral blood. The results suggest that PEGLip-formulated G-CSF may function as an effective and safe tool for the mobilization of HSC prior to bone marrow transplantation. We also identified an amino acid sequence present in proteins that associate with PEGLip but absent from those that do not. A peptide based on this consensus sequence bound PEGLip. The results suggest that PEGLip formulation may serve as a platform for the delivery of additional short-half-life proteins/peptides having the relevant consensus sequence.