Biodegradable poly(amidoamine)s with uniform degradation fragments via sequence-controlled macromonomers

This work presents the translation of sequence-controlled synthesis of macromonomers into sequence-defined and selectively degradable precision polymers.

Comparative pharmacokinetics and pharmacodynamics of a PEGylated recombinant human growth hormone and daily recombinant human growth hormone in growth hormone-deficient children

Objective

Recombinant human growth hormone (rhGH) replacement therapy in children generally requires daily subcutaneous (sc) injections, which may be inconvenient for patients. Jintrolong^® is a PEGylated rhGH with the purpose of weekly sc injections. The aim of the current study was to examine the pharmacokinetics, pharmacodynamics, safety, and tolerability of multiple sc doses of Jintrolong^® vs daily doses of rhGH.

Design and methods

Twelve children with growth hormone deficiency participated in this single-center, open-label, crossover Phase I trial. All subjects received daily sc injections of rhGH at 0.0286 mg/kg/d for 7 days, followed by a 4-week washout period and six weekly doses of Jintrolong^® at 0.2 mg/kg/w.

Results

In comparison with rhGH, sc injection of Jintrolong^® produced a noticeably higher C_max, significantly longer half-life (t_1/2), and slower plasma clearance, signifying a profile suitable for long-term treatment. The ratio of the area under the concentration vs time curve (AUC) after the seventh and first injections (AUC_(0–∞)7th/AUC_(0–∞)1st) of rhGH was 1.02, while the AUC_(0–∞)6th/AUC_(0–∞)1st of Jintrolong ^® was 1.03, indicating no accumulation of circulating growth hormone. There was no significant difference in the change in insulin-like growth factor-1 expression produced by 7 days of sc rhGH and weekly Jintrolong^® injections. There were no severe adverse events during the trial.

Conclusion

The elimination rate of Jintrolong^® was slower than that of sc rhGH. No progressive serum accumulation of Jintrolong^® was found. The changes in insulin-like growth factor-1 expression produced by rhGH and Jintrolong^® were comparable, indicating similar pharmacodynamics. Our results demonstrate that Jintrolong^® is suitable for long-term growth hormone treatment in children with growth hormone deficiency.

Extension of in vivo half-life of biologically active molecules by XTEN protein polymers

XTEN™ is a class of unstructured hydrophilic, biodegradable protein polymers designed to increase the half-lives of therapeutic peptides and proteins. XTEN polymers and XTEN fusion proteins are typically expressed in Escherichia coli and purified by conventional protein chromatography as monodisperse polypeptides of exact length and sequence. Unstructured XTEN polypeptides have hydrodynamic volumes significantly larger than typical globular proteins of similar mass, thus imparting a bulking effect to the therapeutic payloads attached to them. Since their invention, XTEN polypeptides have been utilized to extend the half-lives of a variety of peptide- and protein-based therapeutics. Multiple clinical and preclinical studies and related drug discovery and development efforts are in progress. This review details the most current understanding of physicochemical properties and biological behavior of XTEN and XTENylated molecules. Additionally, the development path and status of several advanced drug discovery and development efforts are highlighted.

Modified NLC-loaded coumarin for pharmaceutical applications: the improvement of physical stability and controlled release profile

BACKGROUND

Coumarin-6 is a lipophilic dye and is often used as a model in delivery system.

OBJECTIVE

The aim of this study was to improve the nonstructured lipid carrier (NLC) system loading with lipophilic molecule, coumarin-6, and to investigate its characteristics in terms of physical stability and controlled release profile.

MATERIALS AND METHODS

Initially, the selection of the coating polymer was observed. Then, the preparation of the conventional NLC-loaded coumarin-6 was compared to the modified NLC-loaded coumarin-6 via the probe sonication. The physical properties and stability were determined by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The release profile was established using fluorescent spectroscopic method.

RESULTS AND DISCUSSION

The size and zeta potential measurement showed significant decrease in the size range of the modified NLC-loaded coumarin and the lower intensity of the surface charge compared to the NLC-loaded coumarin. The change of crystallinity observed from DSC and XRD techniques indicated the molecular dispersion of coumarin-6 in the lipid matrix of NLC. The FT-IR spectra were also proven that coumarin-6 was entrapped in the NLC molecule. The result showed comparable controlled release profile to the conventional preparation with no difference on the cytotoxicity level.

CONCLUSIONS

The modified NLC delivery system, therefore, exhibited the acceptable potential as a nanocarrier.

PEGylated Biopharmaceuticals: Current Experience and Considerations for Nonclinical Development

PEGylation (the covalent binding of one or more polyethylene glycol molecules to another molecule) is a technology frequently used to improve the half-life and other pharmaceutical or pharmacological properties of proteins, peptides, and aptamers. To date, 11 PEGylated biopharmaceuticals have been approved and there is indication that many more are in nonclinical or clinical development. Adverse effects seen with those in toxicology studies are mostly related to the active part of the drug molecule and not to polyethylene glycol (PEG). In 5 of the 11 approved and 10 of the 17 PEGylated biopharmaceuticals in a 2013 industry survey presented here, cellular vacuolation is histologically observed in toxicology studies in certain organs and tissues. No other effects attributed to PEG alone have been reported. Importantly, vacuolation, which occurs mainly in phagocytes, has not been linked with changes in organ function in these toxicology studies. This article was authored through collaborative efforts of industry toxicologists/nonclinical scientists to address the nonclinical safety of large PEG molecules (>10 kilo Dalton) in PEGylated biopharmaceuticals. The impact of the PEG molecule on overall nonclinical safety assessments of PEGylated biopharmaceuticals is discussed, and toxicological information from a 2013 industry survey on PEGylated biopharmaceuticals under development is summarized. Results will contribute to the database of toxicological information publicly available for PEG and PEGylated biopharmaceuticals.

Safety of PEGylated recombinant human full-length coagulation factor VIII (BAX 855) in the overall context of PEG and PEG conjugates

Introduction

BAX 855 is a PEGylated human full‐length recombinant factor VIII (rFVIII) based on licensed rFVIII (ADVATE). The applied PEGylation technology has been optimized to retain functionality of the FVIII molecule, improve its pharmacokinetic properties and allow less frequent injections while maintaining efficacy.

Aim

The aim of this study was to confirm that the excellent safety profile of ADVATE remains unchanged after PEGylation.

Methods

Non‐clinical safety studies with BAX 855 and its respective unbound polyethylene glycol (PEG) were conducted in several species. The distribution of a single dose of radiolabelled BAX 855 was further investigated in rats. Publically available safety data on PEG alone and PEGylated biomolecules were summarized and reviewed for specific safety findings attributable to PEG or PEGylated biopharmaceuticals.

Results

Safety pharmacology studies in rabbits and macaques and repeated dose toxicity studies in rats and macaques identified no safety issues. Results of a distribution study in rats administered radiolabelled BAX 855 showed that radioactivity was completely excreted; urine was the major elimination route. A 28‐day study in rats dosed with the unbound PEG constituent (PEG2ru20KCOOH) of BAX 855 showed no adverse or non‐adverse effects.

Safety data for PEG and PEG‐protein conjugates indicate no safety concerns associated with PEG at clinically relevant dose levels. Although vacuolation of certain cell types has been reported in mammals, no such vacuolation was observed with BAX 855 or with the unbound PEG constituent.

Conclusion

Non‐clinical safety evaluation of PEG and BAX 855 identified no safety signals; the compound is now in clinical development for the treatment of patients with haemophilia A.

A Low Protein Binding Cationic Poly(2-oxazoline) as Non-Viral Vector

Developing safe and efficient non-viral gene delivery systems remains a major challenge. We present a new cationic poly(2-oxazoline) (CPOx) block copolymer for gene therapy that was synthesized by sequential polymerization of non-ionic 2-methyl-2-oxazoline and a new 2-oxazoline monomer, 2-(N-methyl, N-Boc-amino)-methyl-2-oxazoline, followed by deprotection of the pendant secondary amine groups. Upon mixing with plasmid DNA (pDNA), CPOx forms small (diameter ≈80 nm) and narrowly dispersed polyplexes (PDI <0.2), which are stable upon dilution in saline and against thermal challenge. These polyplexes exhibited low plasma protein binding and very low cytotoxicity in vitro compared to the polyplexes of pDNA and poly(ethylene glycol)-b-poly(L-lysine) (PEG-b-PLL). CPOx/pDNA polyplexes at N/P = 5 bound considerably less plasma protein compared to polyplexes of PEG-b-PLL at the same N/P ratio. This is a unique aspect of the developed polyplexes emphasizing their potential for systemic delivery in vivo. The transfection efficiency of the polyplexes in B16 murine melanoma cells was low after 4 h, but increased significantly for 10 h exposure time, indicative of slow internalization of polyplexes. Addition of Pluronic P85 boosted the transfection using CPOx/pDNA polyplexes considerably. The low protein binding of CPOx/pDNA polyplexes is particularly interesting for the future development of targeted gene delivery.

Early implementation of QbD in biopharmaceutical development: a practical example

In drug development, the “onus” of the low R&D efficiency has been put traditionally onto the drug discovery process (i.e., finding the right target or “binding” functionality). Here, we show that manufacturing is not only a central component of product success, but also that, by integrating manufacturing and discovery activities in a “holistic” interpretation of QbD methodologies, we could expect to increase the efficiency of the drug discovery process as a whole. In this new context, early risk assessment, using developability methodologies and computational methods in particular, can assist in reducing risks during development in a cost-effective way. We define specific areas of risk and how they can impact product quality in a broad sense, including essential aspects such as product efficacy and patient safety. Emerging industry practices around developability are introduced, including some specific examples of applications to biotherapeutics. Furthermore, we suggest some potential workflows to illustrate how developability strategies can be introduced in practical terms during early drug development in order to mitigate risks, reduce drug attrition and ultimately increase the robustness of the biopharmaceutical supply chain. Finally, we also discuss how the implementation of such methodologies could accelerate the access of new therapeutic treatments to patients in the clinic.

Differential effects of commercial-grade and purified poloxamer 188 on renal function

Poloxamer 188 (P188) is a non-ionic amphiphilic copolymer with hemorheologic, antithrombotic, anti-inflammatory, and cytoprotective properties. It potentially has clinical utility in diverse diseases, such as acute myocardial infarction, acute limb ischemia, shock, acute stroke, heart failure, and sickle cell crisis. P188 is available as an excipient-grade product, manufactured to National Formulary specifications, which we refer to as P188-NF. During synthesis of P188-NF, polymerization of its polyoxyethylene and polyoxypropylene components generates undesirable low molecular weight (LMW) substances, such as truncated polymers and glycols. In early clinical studies, P188-NF yielded unexpected renal dysfunction. Here, we explore the nature of the renal dysfunction associated with P188-NF and use a purified (more homogenous) form of P188-NF (P188-P) to show that removal of LMW substances is associated with substantially less renal dysfunction. In both a remnant-kidney animal model and in clinical studies, P188-P demonstrates a substantially improved renal safety profile.

Fibril aggregates of the poly(glutamic acid)–drug conjugate

Poly(glutamic acid)–doxorubicin conjugates form fibrillar aggregates in the aqueous solution.

Recent advances in targeted nanoparticles drug delivery to melanoma

Melanoma is one of the most aggressive skin cancers, notorious for its high multidrug resistance and low survival rate. Conventional therapies (e.g., dacarbazine, interferon-alpha-2b and interleukin-2) are limited by low response rate and demonstrate no overall survival benefit. Novel targeted therapies (e.g., vemurafenib, dabrafenib and trametinib) have higher initial response rate and clear impact on the overall survival, but relapse usually occurs within 6 to 9 months. Although immunotherapy (e.g., ipilimumab, pembrolizumab and nivolumab) can achieve long-term and durable response, rate of adverse events is extremely high. With the development of nanotechnology, the applications of nanocarriers are widely expected to change the landscape of melanoma therapy for foreseeable future. In this review, we will relate recent advances in the application of multifunctional nanocarriers for targeted drug delivery to melanoma, in melanoma nanotheranostics and combination therapy, and nanopharmaceutical associated melanoma clinical trials, followed by challenges and perspectives. From the clinical editor: The team of authors describes the current treatment regimes of malignant melanoma emphasizing the importance of achieving a better efficacy and the need to develop a better understanding of melanoma tumorigenesis.

Head to head comparison of the formulation and stability of concentrated solutions of HESylated versus PEGylated anakinra

Although PEGylation of biologics is currently the gold standard for half-life extension, the technology has a number of limitations, most importantly the non-biodegradability of PEG and the extremely high viscosity at high concentrations. HESylation is a promising alternative based on coupling to the biodegradable polymer hydroxyethyl starch (HES). In this study, we are comparing HESylation with PEGylation regarding the effect on the protein's physicochemical properties, as well as on formulation at high concentrations, where protein stability and viscosity can be compromised. For this purpose, the model protein anakinra is coupled to HES or PEG by reductive amination. Results show that coupling of HES or PEG had practically no effect on the protein's secondary structure, and that it reduced protein affinity by one order of magnitude, with HESylated anakinra more affine than the PEGylated protein. The viscosity of HESylated anakinra at protein concentrations up to 75 mg/mL was approximately 40% lower than that of PEG-anakinra. Both conjugates increased the apparent melting temperature of anakinra in concentrated solutions. Finally, HESylated anakinra was superior to PEG-anakinra regarding monomer recovery after 8 weeks of storage at 40°C. These results show that HESylating anakinra offers formulation advantages compared with PEGylation, especially for concentrated protein solutions.

Fundamentals of translational neuroscience in toxicologic pathology: optimizing the value of animal data for human risk assessment

A half-day Society of Toxicologic Pathology continuing education course on "Fundamentals of Translational Neuroscience in Toxicologic Pathology" presented some current major issues faced when extrapolating animal data regarding potential neurological consequences to assess potential human outcomes. Two talks reviewed functional-structural correlates in rodent and nonrodent mammalian brains needed to predict behavioral consequences of morphologic changes in discrete neural cell populations. The third lecture described practical steps for ensuring that specimens from rodent developmental neurotoxicity tests will be processed correctly to produce highly homologous sections. The fourth talk detailed demographic factors (e.g., species, strain, sex, and age); physiological traits (body composition, brain circulation, pharmacokinetic/pharmacodynamic patterns, etc.); and husbandry influences (e.g., group housing) known to alter the effects of neuroactive agents. The last presentation discussed the appearance, unknown functional effects, and potential relevance to humans of polyethylene glycol (PEG)-associated vacuoles within the choroid plexus epithelium of animals. Speakers provided real-world examples of challenges with data extrapolation among species or with study design considerations that may impact the interpretability of results. Translational neuroscience will be bolstered in the future as less invasive and/or more quantitative techniques are devised for linking overt functional deficits to subtle anatomic and chemical lesions.

Early engineering approaches to improve peptide developability and manufacturability

Downstream success in Pharmaceutical Development requires thoughtful molecule design early in the lifetime of any potential therapeutic. Most therapeutic monoclonal antibodies are quite similar with respect to their developability properties. However, the properties of therapeutic peptides tend to be as diverse as the molecules themselves. Analysis of the primary sequence reveals sites of potential adverse posttranslational modifications including asparagine deamidation, aspartic acid isomerization, methionine, tryptophan, and cysteine oxidation and, potentially, chemical and proteolytic degradation liabilities that can impact the developability and manufacturability of a potential therapeutic peptide. Assessing these liabilities, both biophysically and functionally, early in a molecule's lifetime can drive a more effective path forward in the drug discovery process. In addition to these potential liabilities, more complex peptides that contain multiple disulfide bonds can pose particular challenges with respect to production and manufacturability. Approaches to reducing the disulfide bond complexity of these peptides are often explored with mixed success. Proteolytic degradation is a major contributor to decreased half-life and efficacy. Addressing this aspect of peptide stability early in the discovery process increases downstream success. We will address aspects of peptide sequence analysis, molecule complexity, developability analysis, and manufacturing routes that drive the decision making processes during peptide therapeutic development.

Half-life extension technologies for haemostatic agents

The use of plasma-derived and recombinant coagulation factors for the treatment of haemophilia A and B is well established and permits patients to live a relatively normal life. In order to improve treatment options, several products are in development, which have a prolonged duration of action, thus enabling less frequent prophylactic dosing and aiming to reduce the burden of treatment. Several innovative approaches are being pursued to extend the half-life of factor VIIa, factor VIII and factor IX, utilising technologies such as Fc fusion, recombinant albumin fusion and addition of polyethyleneglycol (PEG) (PEGylation). These methods prolong the time in the circulation by reducing degradation and elimination. This review summarises the technologies and products in development and their stages of development, and also discusses their pros and cons.

Pharmacokinetics, metabolism and distribution of PEGs and PEGylated proteins: quo vadis?

The pharmacokinetics (PK), metabolism and biodistribution of polyethylene glycol (PEG) in PEGylated proteins are important to understand the increased cellular vacuolation reported in various tissues in animals. The tissue distribution profile of PEGylated proteins and 'metabolic' PEG is guided largely by absolute PEG load, PEG molecular weight and, where applicable, receptor-mediated uptake via the protein moiety. High molecular weight PEGs show slow renal clearance, and consequently have a greater potential to accumulate within cells. The intracellular nonbiodegradable PEG can accumulate within the lysosome ultimately causing distension and vacuolation observed by standard histological examinations. Improved bioanalytical methodologies will contribute to the identification of specific PK parameters including distribution behavior to support development of PEGylated proteins as therapeutics.

Pharmacologic profile of the Adnectin BMS-962476, a small protein biologic alternative to PCSK9 antibodies for low-density lipoprotein lowering

Proprotein convertase subtilisin kexin-9 (PCSK9) is an important pharmacological target for decreasing low-density lipoprotein (LDL) in cardiovascular disease, although seemingly inaccessible to small molecule approaches. Compared with therapeutic IgG antibodies currently in development, targeting circulating PCSK9 with smaller molecular scaffolds could offer different profiles and reduced dose burdens. This inspired genesis of PCSK9-binding Adnectins, a protein family derived from human fibronectin-10th-type III-domain and engineered for high-affinity target binding. BMS-962476, an ∼11-kDa polypeptide conjugated to polyethylene glycol to enhance pharmacokinetics, binds with subnanomolar affinity to human. The X-ray cocrystal structure of PCSK9 with a progenitor Adnectin shows ∼910 Å(2) of PCSK9 surface covered next to the LDL receptor binding site, largely by residues of a single loop of the Adnectin. In hypercholesterolemic, overexpressing human PCSK9 transgenic mice, BMS-962476 rapidly lowered cholesterol and free PCSK9 levels. In genomic transgenic mice, BMS-962476 potently reduced free human PCSK9 (ED50 ∼0.01 mg/kg) followed by ∼2-fold increases in total PCSK9 before return to baseline. Treatment of cynomolgus monkeys with BMS-962476 rapidly suppressed free PCSK9 >99% and LDL-cholesterol ∼55% with subsequent 6-fold increase in total PCSK9, suggesting reduced clearance of circulating complex. Liver sterol response genes were consequently downregulated, following which LDL and total PCSK9 returned to baseline. These studies highlight the rapid dynamics of PCSK9 control over LDL and liver cholesterol metabolism and characterize BMS-962476 as a potent and efficacious PCSK9 inhibitor.

Pre-clinical toxicokinetics and safety study of M2ES, a PEGylated recombinant human endostatin, in rhesus monkeys

PEGylated recombinant human endostatin (M2ES) exhibited prolonged serum half-life and enhanced antitumor activity when compared with endostatin. A non-clinical study was performed to evaluate the toxicokinetics and safety of M2ES in rhesus monkeys. After intravenous (IV) infusions of M2ES at a dose level of 3, 10, and 30mg/kg in rhesus monkeys, the concentration-time curves of M2ES were best fitted to a non-compartment model, and area under the curve (AUC) was positively correlated with the dosage. M2ES had a tendency to accumulate in vivo following successive IV infusions. Serum anti-M2ES IgG antibodies were generated quickly during IV administration, and the antibody level in serum did not significantly decrease after four-week recovery period. Animals administered IV infusions twice weekly (M2ES at 10 or 30mg/kg body weight per day) for 3months developed mild or moderate vacuolation of proximal tubule epithelial cell in proximal convoluted tubule of kidney, but this adverse-effect was reversible. In summary, M2ES was well tolerated and did not cause any serious toxicity. These pre-clinical safety data contribute to the initiation of the ongoing clinical study.

Extension of in vivo half-life of biologically active peptides via chemical conjugation to XTEN protein polymer

XTEN, unstructured biodegradable proteins, have been used to extend the in vivo half-life of genetically fused therapeutic proteins and peptides. To expand the applications of XTEN technology to half-life extension of other classes of molecules, XTEN protein polymers and methods for chemical XTENylation were developed. Two XTEN precursors were engineered to contain enzymatically removable purification tags. The proteins were readily expressed in bacteria and purified to homogeneity by chromatography techniques. As proof-of-principle, GLP2-2G peptide was chemically conjugated to each of the two XTEN protein polymers using maleimide-thiol chemistry. The monodisperse nature of XTEN protein polymer enabled reaction monitoring as well as the detection of peptide modifications in the conjugated state using reverse phase-high performance liquid chromatography (RP-HPLC) and electrospray ionization mass spectrometry. The resulting GLP2-2G-XTEN conjugates were purified by preparative RP-HPLC to homogeneity. In comparison with recombinantly fused GLP2-2G-XTEN, chemically conjugated GLP2-2G-XTEN molecules exhibited comparable in vitro activity, in vitro plasma stability and pharmacokinetics in rats. These data suggest that chemical XTENylation could effectively extend the half-life of a wide spectrum of biologically active molecules, therefore broadening its applicability.