Formulation of cell-based medicinal products: a question of life or death?

The formulation of cell-based medicinal products (CBMPs) poses major challenges because of their complexity, heterogeneity, interaction with their environment (e.g., the formulation buffer, interfaces), and susceptibility to degradation. These challenges can be quality, safety, and efficacy related. In this commentary we discuss the current status in formulation strategies of off-the-shelf and non-off-the-shelf (patient-specific) CBMPs and highlight advantages and disadvantages of each strategy. Analytical tools for the characterization and stability assessment of CBMP formulations are addressed as well. Finally, we discuss unmet needs and make some recommendations regarding the formulation of CBMPs. (C) 2020 American Pharmacists Association?. Published by Elsevier Inc. All rights reserved.Personalised Therapeutic

Rapid aggregation of therapeutic monoclonal antibodies by bubbling induced air/liquid interfacial and agitation stress at different conditions

Degradation of therapeutic monoclonal antibodies (mAb) due to interfacial agitation through air bubbling was investigated. Samples containing mAb in phosphate buffered saline were subjected to rapid bubbling by using a peristaltic pump at an air flow rate of 11.5 mL/min. Samples were analyzed by visual observation, UV-Vis, fluorescence, circular dichroism and infrared spectroscopy, size-exclusion chromatography (SEC), dynamic light scattering, microscopy, and cell-based activity assays. The stressed samples showed increasing turbidity with bubbling time, with mAb1 showing a protein loss of 53% in the supernatant at the latest time point (240 min), indicating formation of sub-visible and visible aggregates. Aggregate rich samples exhibited altered secondary structure and higher hydrophobicity with 40% reduction in activity. The supernatants of the stressed samples showed unchanged secondary and tertiary structure without the presence of any oligomers in SEC. Furthermore, the impact of various factors that could affect aggregation was investigated and it was found that the extent of aggregation was affected by protein concentration, sample volume, presence of surfactants, temperature, air flow rate, and presence of silicone oil. In conclusion, exposure to air/liquid interfacial stress through bubbling into liquid mAb samples effectively generated sub-visible and visible aggregates, making air bubbling an attractive approach for interfacial stress degradation studies of mAbs.Drug Delivery Technolog

A New Strategy to Stabilize Oxytocin in Aqueous Solutions: I. The Effects of Divalent Metal Ions and Citrate Buffer

In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. and divalent metal ions (Ca2+, Mg2+, and Zn2+) were tested all as chloride salts. The effect of combinations of buffers and metal ions on the stability of aqueous oxytocin solutions was determined by RP-HPLC and HP-SEC after 4 weeks of storage at either 4°C or 55°C. Addition of sodium or potassium ions to acetate- or citrate-buffered solutions did not increase stability, nor did the addition of divalent metal ions to acetate buffer. However, the stability of aqueous oxytocin in aqueous formulations was improved in the presence of 5 and 10 mM citrate buffer in combination with at least 2 mM CaCl2, MgCl2, or ZnCl2 and depended on the divalent metal ion concentration. Isothermal titration calorimetric measurements were predictive for the stabilization effects observed during the stability study. Formulations in citrate buffer that had an improved stability displayed a strong interaction between oxytocin and Ca2+, Mg2+, or Zn2+, while formulations in acetate buffer did not. In conclusion, our study shows that divalent metal ions in combination with citrate buffer strongly improved the stability of oxytocin in aqueous solutions

Formulation, Delivery and Stability of Bone Morphogenetic Proteins for Effective Bone Regeneration

Drug Delivery Technolog

Label-Free, Flow-Imaging Methods for Determination of Cell Concentration and Viability

To investigate the potential of two flow imaging microscopy (FIM) techniques (Micro-Flow Imaging (MFI) and FlowCAM) to determine total cell concentration and cell viability. B-lineage acute lymphoblastic leukemia (B-ALL) cells of 2 different donors were exposed to ambient conditions. Samples were taken at different days and measured with MFI, FlowCAM, hemocytometry and automated cell counting. Dead and live cells from a fresh B-ALL cell suspension were fractionated by flow cytometry in order to derive software filters based on morphological parameters of separate cell populations with MFI and FlowCAM. The filter sets were used to assess cell viability in the measured samples. All techniques gave fairly similar cell concentration values over the whole incubation period. MFI showed to be superior with respect to precision, whereas FlowCAM provided particle images with a higher resolution. Moreover, both FIM methods were able to provide similar results for cell viability as the conventional methods (hemocytometry and automated cell counting). FIM-based methods may be advantageous over conventional cell methods for determining total cell concentration and cell viability, as FIM measures much larger sample volumes, does not require labeling, is less laborious and provides images of individual cells. PURPOSE METHODS RESULTS CONCLUSIONDrug Delivery Technolog

Chemical Modifications of Gold Surfaces with Basic Groups and a Fluorescent Nanoparticle Adhesion Assay To Determine Their Surface pKa

For pharmaceutical, biological, and biomedical applications, the functionalization of gold surfaces with pH-sensitive groups has great potential. The aim of this work was to modify gold surfaces with pH-sensitive groups and to determine the pKa of the modified gold surfaces using a fluorescent nanoparticle adhesion assay. To introduce pH-sensitive groups onto gold surfaces, we modified gold-coated silicon slides with four different bases: 4-mercaptopyridine (4-MP), 4-pyridylethylmercaptan (4-PEM), 4-aminothiophenol (4-ATP), and 2-mercaptoethylamine (2-MEA). To screen whether the modifications were successful, the binding of negatively charged fluorescently labeled nanoparticles to the positively charged surfaces was visualized by fluorescence microscopy and atomic force microscopy. Next, the pKa of the modified surfaces was determined by quantifying the pH-dependent adhesion of the fluorescently labeled nanoparticles with fluorescence spectroscopy. Fluorescence microscopy showed that the gold surfaces were successfully modified with the four different basic molecules. Moreover, fluorescence spectroscopy revealed that fluorescently labeled negatively charged nanoparticles bound onto gold surfaces that were modified with one of the four bases in a pH-dependent manner. By quantifying the adsorption of negatively charged fluorescently labeled nanoparticles onto the functionalized gold surfaces and using the Henderson–Hasselbalch equation, the pKa of these surfaces was determined to be 3.7 ± 0.1 (4-MP), 5.0 ± 0.1 (4-PEM), 5.4 ± 0.1 (4-ATP), and 7.4 ± 0.3 (2-MEA). We successfully functionalized gold surfaces with four different basic molecules, yielding modified surfaces with different pKa values, as determined with a fluorescent nanoparticle adhesion assay.Drug Delivery Technolog

Formaldehyde treatment of proteins enhances proteolytic degradation by the endo-lysosomal protease cathepsin S

Enzymatic degradation of protein antigens by endo-lysosomal proteases in antigen-presenting cells is crucial for achieving cellular immunity. Structural changes caused by vaccine production process steps, such as formaldehyde inactivation, could affect the sensitivity of the antigen to lysosomal proteases. The aim of this study was to assess the effect of the formaldehyde detoxification process on the enzymatic proteolysis of antigens by studying model proteins. Bovine serum albumin, β-lactoglobulin A and cytochrome c were treated with various concentrations of isotopically labelled formaldehyde and glycine, and subjected to proteolytic digestion by cathepsin S, an important endo-lysosomal endoprotease. Degradation products were analysed by mass spectrometry and size exclusion chromatography. The most abundant modification sites were identified by their characteristic MS doublets. Unexpectedly, all studied proteins showed faster proteolytic degradation upon treatment with higher formaldehyde concentrations. This effect was observed both in the absence and presence of glycine, an often-used excipient during inactivation to prevent intermolecular crosslinking. Overall, subjecting proteins to formaldehyde or formaldehyde/glycine treatment results in changes in proteolysis rates, leading to an enhanced degradation speed. This accelerated degradation could have consequences for the immunogenicity and the efficacy of vaccine products containing formaldehyde-inactivated antigens.Drug Delivery Technolog

Cationic nanoparticle-based cancer vaccines

Cationic nanoparticles have been shown to be surprisingly effective as cancer vaccine vehicles in preclinical and clinical studies. Cationic nanoparticles deliver tumor-associated antigens to dendritic cells and induce immune activation, resulting in strong antigen-specific cellular immune responses, as shown for a wide variety of vaccine candidates. In this review, we discuss the relation between the cationic nature of nanoparticles and the efficacy of cancer immunotherapy. Multiple types of lipid- and polymer-based cationic nanoparticulate cancer vaccines with various antigen types (e.g., mRNA, DNA, peptides and proteins) and adjuvants are described. Furthermore, we focus on the types of cationic nanoparticles used for T-cell induction, especially in the context of therapeutic cancer vaccination. We discuss different cationic nanoparticulate vaccines, molecular mechanisms of adjuvanticity and biodistribution profiles upon administration via different routes. Finally, we discuss the perspectives of cationic nanoparticulate vaccines for improving immunotherapy of cancer.Tumorimmunolog

Ongoing challenges to develop high concentration monoclonal antibody-based formulations for subcutaneous administration: Quo Vadis?

Although many subcutaneously (s.c.) delivered, high-concentration antibody formulations (HCAF) have received regulatory approval and are widely used commercially, formulation scientists are still presented with many ongoing challenges during HCAF development with new mAb and mAb-based candidates. Depending on the specific physicochemical and biological properties of a particular mAb-based molecule, such challenges vary from pharmaceutical attributes e.g., stability, viscosity, manufacturability, to clinical performance e.g., bioavailability, immunogenicity, and finally to patient experience e.g., preference for s.c. vs. intravenous delivery and/or preferred interactions with health-care professionals. This commentary focuses on one key formulation obstacle encountered during HCAF development: how to maximize the dose of the drug? We examine methodologies for increasing the protein concentration, increasing the volume delivered, or combining both approaches together. We discuss commonly encountered hurdles, i.e., physical protein instability and solution volume limitations, and we provide recommendations to formulation scientists to facilitate their development of s.c. administered HCAF with new mAb-based product candidates.Drug Delivery Technolog

PLGA particulate delivery systems for subunit vaccines: linking particle properties to immunogenicity.

Among the emerging subunit vaccines are recombinant protein- and synthetic peptide-based vaccine formulations. However, proteins and peptides have a low intrinsic immunogenicity. A common strategy to overcome this is to co-deliver (an) antigen(s) with (an) immune modulator(s) by co-encapsulating them in a particulate delivery system, such as poly(lactic-co-glycolic acid) (PLGA) particles. Particulate PLGA formulations offer many advantages for antigen delivery as they are biocompatible and biodegradable; can protect the antigens from degradation and clearance; allow for co-encapsulation of antigens and immune modulators; can be targeted to antigen presenting cells; and their particulate nature can increase uptake and cross-presentation by mimicking the size and shape of an invading pathogen. In this review we discuss the pros and cons of using PLGA particulate formulations for subunit vaccine delivery and provide an overview of formulation parameters that influence their adjuvanticity and the ensuing immune response.Drug Delivery Technolog