The 32nd Annual Meeting of German Society of Immunology

The use of unmodified asparaginases (ASP) in the management of pediatric and adult acute lymphoblastic leukemia (ALL) is well established. Despite its well-proven clinical efficacy, the use of unmodified Escherichia coli ASP (EC-ASP) has been limited by frequent toxicities, especially the development of hypersensitivity reactions and neutralizing antibodies, and by the need for frequent administration. To overcome these limitations, EC-ASP enzyme was covalently linked to monomethoxypolyethylene glycol (PEG), forming the pegylated ASP (PEG-ASP) (Oncaspar^®). PEG-ASP has a prolonged half-life and is associated with decreased immunogenicity when compared with EC-ASP. Clinical trials have demonstrated the efficacy, safety and tolerability of PEG-ASP administered intramuscularly, subcutaneously or intravenously as part of multi-agent chemotherapy regimens in the management of newly diagnosed and relapsed pediatric and adult ALL. Here we discuss the pharmacology, pharmacokinetics, clinical trial results and potential side effects of PEG-ASP.     

聚乙二醇化重组人粒细胞集落刺激因子预防化疗后中性粒细胞减少的临床观察

目的比较聚乙二醇化重组人粒细胞集落刺激因子（PEG-rhG-CSF）和重组人粒细胞集落刺激因子（rhG．CSF）预防化疗后中性粒细胞减少症的有效性和安全性。方法采用随机自身交叉对照,纳入42例初治恶性肿瘤患者,接受2个周期相同方案的化疗,其中试验周期给予PEG—rhG-CSF100μg／kg皮下注射1次,对照周期皮下注射rhG-CSF5阻异／（kg·d）直至外周血中性粒细胞绝对值（ANC）达低谷后连续2次检查≥5．0×10^9／L。结果42例患者,在40个试验周期和44个对照周期中,ANC〈2．0×10^9／L的发生率试验组和对照组分别为30％（12／40）和31.8％（14／44）,持续时间分别为（3±1．155）d和（4±1．225）d;受试药和对照药的不良反应均主要为骨骼肌肉疼痛、乏力、发热、头晕等,发生率与严重程度相似。结论PEG-rhG-CSF-次给药的疗效与与rhG-CSF多次给药相似,不良反应低。     

Comparison between protein repulsions by diblock PLA-PEO and albumin nanocoatings using OWLS

A previous investigation suggested that a surface bearing a rinsing-resistant depot (nanocoating) of albumin is more protein-repulsive than the same surface physically pegylated by a poly(D,L-lactic acid)-poly(ethylene oxide) diblock copolymer. To complement the study, Optical Waveguide Lightmode Spectroscopy was used to compare the mass and the thickness of protein depots from different systems, namely albumin alone at different concentrations, a mixture of albumin + fibrinogen + γ-globulin at their physiological concentrations, and sheep serum. The same standard OWLS protocol was applied to compare data for bare sensor chips, for chips covered by an albumin nanocoating, and for chips physically pegylated using poly(D,L-lactic acid)-poly(ethylene oxide) diblock copolymers with different compositions and block lengths. The strategy and the conditions being rather different from those generally used to study pegylation-related antifouling properties; the literature was first reviewed critically. Then full coverage of sensor chips by albumin was demonstrated. The comparative study confirmed that albumin was more protein-repulsive than any of the diblock copolymers, irrespective of the protein system. Furthermore, it was found that pegylated surfaces were albumin-repulsive only when the concentration of the protein solution flowing over the surface was very low (0.1 g/L). It was not possible to correlate the copolymer data to PEO chain density, chain length and existence of brush. The in vitro repulsive activity of albumin was not affected by drying and rehydration, a feature of interest for storage of albumin-coated surfaces. All these observations confirmed our preliminary findings and showed that considering model proteins individually or in mixtures at concentrations far from physiological concentrations are not suitable to reflect the reality of full blood-surface interactions.     

聚乙二醇衍生物及其蛋白药物修饰研究进展

聚乙二醇及其衍生物因其出色的亲水性、生物相容性、生物学惰性等特性而被广泛应用于蛋白药物修饰,其修饰可有效降低蛋白药物的免疫原性并延长体内半衰期。聚乙二醇衍生物的发展经历了第一代随机修饰,第二代特异性和功能性修饰,以及第三代分支型结构的应用。其应用也从简单的药物修饰扩展到生物传感、药物传输等方面。     

Formulation Development,Optimization, and In Vitro–In Vivo Characterization of Natamycin-Loaded PEGylated Nano-Lipid Carriers for Ocular Applications

The present study aimed at formulating and optimizing natamycin (NT)-loaded polyethylene glycosylated nano-lipid carriers (NT-PEG-NLCs) using Box-Behnken design and investigating their potential in ocular applications. Response surface methodology computations and plots for optimization were performed using Design-Expert^® software to obtain optimum values for response variables based on the criteria of desirability. Optimized NT-PEG-NLCs had predicted values for the dependent variables which are not significantly different from the experimental values. NT-PEG-NLCs were characterized for their physicochemical parameters; NT's rate of permeation and flux across rabbit cornea was evaluated, in vitro, and ocular tissue distribution was assessed in rabbits, in vivo. NT-PEG-NLCs were found to have optimum particle size (<300 nm), narrow polydispersity index, and high NT entrapment and NT content. In vitro transcorneal permeability and flux of NT from NT-PEG-NLCs was significantly higher than that of Natacyn^®. NT-PEG-NLC (0.3%) showed improved delivery of NT across the intact cornea and provided concentrations statistically similar to the marketed suspension (5%) in inner ocular tissues, in vivo, indicating that it could be a potential alternative to the conventional suspension during the course of fungal keratitis therapy.     

Carboxyl-directed Pegylation of Brain-derived Neurotrophic Factor Markedly Reduces Systemic Clearance with Minimal Loss of Biologic Activity

Purpose. Brain-derived neurotrophic factor (BDNF) was modified by carboxyl-directed protein pegylation in order to both retain biologic activity of the neurotrophin and reduce the rate of systemic clearance of this cationic protein in vivo. Since the modification of surface lysine residues of neurotrophins results in loss of biologic activity, the present studies examine the feasibility of placing polyethyleneglycol (PEG) polymers on carboxyl residues of surface glutamate or aspartate residues of BDNF. Methods. PEG molecules with terminal hydrazide (Hz) moieties of molecular weight 2,000 (PEG²⁰⁰⁰-Hz) or 5,000 (PEG⁵⁰⁰⁰-Hz) Daltons were coupled to BDNF carboxyls using carbodiimide. Results. The systemic clearances of the BDNF-PEG²⁰⁰⁰ and BDNF-PEG⁵⁰⁰⁰ were reduced 67% and 91%, respectively, compared to unconjugated BDNF. The brain volume of distribution (V_D) of BDNF-PEG⁵⁰⁰⁰ was not significantly different from the cerebral plasma volume. Cell survival studies and TrkB auto-phosphorylation assays showed that the biologic activity of BDNF was not changed following pegylation with PEG²⁰⁰⁰, and was minimally impaired following pegylation with PEG⁵⁰⁰⁰. Conclusions. These experiments describe the first carboxyl-directed pegylation of a neuropeptide, and show this formulation substantially reduces the systemic distribution and elimination of the neurotrophic factor. The biologic activity of the neurotrophin is retained with carboxyl-directed pegylation.     

Experimental photodynamic therapy for malignant pleural mesothelioma with pegylated mTHPC

BACKGROUND AND OBJECTIVES: Experimental assessment of photodynamic therapy (PDT) for malignant pleural mesothelioma using a polyethylene glycol conjugate of meta-tetrahydroxyphenylchlorin (PEG-mTHPC). STUDY DESIGN/MATERIALS AND METHODS: (a) PDT was tested on H-meso-1 xenografts (652 nm laser light; fluence 10 J/cm(2); 0.93, 9.3, or 27.8 mg/kg of PEG-mTHPC; drug-light intervals 3-8 days). (b) Intraoperative PDT with similar treatment conditions was performed in the chest cavity of minipigs (n = 18) following extrapleural pneumonectomy (EPP) using an optical integrating balloon device combined with in situ light dosimetry. RESULTS: (a) PDT using PEG-mTHPC resulted in larger extent of tumor necrosis than in untreated tumors (P < or = 0.01) without causing damage to normal tissue. (b) Intraoperative PDT following EPP was well tolerated in 17 of 18 animals. Mean fluence and fluence rates measured at four sites of the chest cavity ranged from 10.2 +/- 0.2 to 13.2 +/- 2.3 J/cm(2) and 5.5 +/- 1.2 to 7.9 +/- 1.7 mW/cm(2) (mean +/- SD). Histology 3 months after light delivery revealed no PDT related tissue injury in all but one animal. CONCLUSIONS: PEG-mTHPC mediated PDT showed selective destruction of mesothelioma xenografts without causing damage to intrathoracic organs in pigs at similar treatment conditions. The light delivery system afforded regular light distribution to different parts of the chest cavity.     

Treatment of chronic hepatitis B

In the last years, marked progress has been made in the treatment of chronic hepatitis B. The efficacy of lamivudine, the first nucleoside analogue available, is limited by the high incidence of resistance. Adefovir, which was recently approved has a comparable efficacy with a very low frequency of resistance. However, adefovir needs to be indefinitely administered as withdrawal of therapy is generally associated with reactivation and sustained response is uncommon. Recent large randomized controlled trials showed that PEG IFNs induce relatively high sustained response rates both in HBeAg positive and HBeAg negative chronic hepatitis B. So far, the combination of PEG IFN with lamivudine, used simultaneously, is disappointing in terms of short-term efficacy. However, long-term efficacy needs to be assessed and different schedules of combination (for example sequential) need to be evaluated. A number of nucleoside analogues, with favourable toxicity profiles and a promise of increased effectiveness against HBV, are at various stages of clinical development. Results of phase III trials of entecavir and emtricitabine confirmed their efficacy. However, while entecavir is associated with a low incidences of resistance, emtricitabine is associated with a relatively high incidence of resistance which limits its use as a monotherapy. The efficacy and safety of new and more potent drugs like telbivudine and clevudine need to be confirmed. The future of chronic hepatitis B therapy seems to be in the combination of different drugs. Ideally, the optimal drugs to combine would meet the following criteria: they should have different sites of action on HBV DNA replication, a potent antiviral effect, an excellent safety profile and they should induce a sustained response with a limited duration of therapy. Indeed, the concept of combination therapy has been recently developed in order to increase efficacy and to decrease the occurrence of viral resistance. However, so far few combinations have been evaluated. No combination therapy demonstrated a benefit as compared with monotherapy. More potent drugs and new combinations together with the understanding of the mechanisms of resistance to therapy are important challenges to improve the efficacy of treatment and decrease in the future the global burden related to chronic hepatitis B.     

In vivo brain microdialysis to evaluate FITC-dextran encapsulated immunopegylated nanoparticles

Context: Delivery of drugs and dyes through intact blood–brain barrier (BBB) is extremely sought-after. A safe and reliable measurement of delivery efficacy in live animals is necessary.

Objective: To investigate the brain uptake of FITC-dextran MW 4000 (FD4) by CD71/OX-26 coated nanoparticles by microdialysis sampling and fluorescence/confocal microscopy.

Materials and methods: Methoxy-poly(ethylene glycol)-poly(lactide) (Met-PEG-PLA) and maleimide-poly(ethylene glycol)-poly(lactide) (Mal-PEG-PLA) nanoparticles were prepared by nanoprecipitation. The surfaces of the prepared nanoparticles were embellished with CD-71/OX-26 antibodies for brain targeting. Male Sprague Dawley rats received 0.4?mg/kg FD4 and equivalent nanoparticulate formulation through lateral tail vein. Animals were euthanized 24?h postadministration, after which the tissues were harvested and analyzed for FD4 concentrations. Tissues were fixed with paraformaldehyde, cryotomed to 20 µm sections, and analyzed by Total Internal Reflection microscopy.

Results: Particle sizes of 200?±?25?nm and zeta potentials of ?18?±?1 mV were obtained. FD4 concentrations, determined using in vivo brain microdialysis, were high on the first day (~360?ng/mL) compared to 60?ng/mL on the following 2 days. The nanoparticle treated animals showed significantly higher (p < 0.05) FD4 concentrations in the brain than pure-FD4 treated animals. Immunopegylated nanoparticles sustained and enhanced Central nervous system (CNS) concentration of hydrophilic dye for at least 3 days.

Conclusion: Immunopegylated nanoparticles produce enhanced and sustained uptake of brain permeability marker FD4 relative to controls.     

Single-use autoinjector for peginterferon-β1a treatment of relapsing-remitting multiple sclerosis: safety,tolerability and patient evaluation data from the Phase IIIb ATTAIN study

Objectives: A sub-study to evaluate safety, tolerability, ease-of-use and patient satisfaction with a single-use autoinjector administering subcutaneous peginterferon-β_1a (a pegylated interferon-β_1a in clinical development) in a subset of relapsing-remitting multiple sclerosis (MS) patients participating in ATTAIN, a long-term dose-frequency blinded extension of the Phase III randomized ADVANCE study.

Methods: Over 8 weeks, patients self-administered peginterferon-β_1a 125 µg or placebo every 2 weeks (two injections via manual pre-filled syringe [PFS]; two injections via single-use autoinjector). Primary end points were incidence of adverse events (AEs), patient assessment of injection pain score (10-point Visual Analog Scale), and clinician assessment of injection site reactions (ISRs). Secondary objectives included patient assessment of ease-of-use and satisfaction with the autoinjector and evaluation of autoinjector training materials.

Results: In 39 patients, the safety profile of peginterferon-β_1a was similar when delivered via autoinjector or PFS; AEs were mostly mild or moderate in severity. Clinicians and patients reported a similar tolerability profile using both PFS and autoinjector, and pain scores were low (< 1), with no reports of clinician-assessed ISRs after administration with the autoinjector. Patients perceived the single-use autoinjector to be easy to use and convenient; overall patient satisfaction with the autoinjector and accompanying training materials was high.

Conclusion: The safety and tolerability profile of peginterferon-β_1a delivered via autoinjector was similar to delivery via PFS. Patients found the autoinjector easy to use and convenient; this device may simplify the injection process for MS patients who require long-term therapy, thereby potentially improving patient’s quality of life and adherence.