Stabilization of a model formalinized protein antigen encapsulated in poly(lactide- co -glycolide)-based microspheres

A formaldehyde-mediated aggregation pathway (FMAP) has been shown to be primarily responsible for the solid-state aggregation of lyophilized formalinized protein antigens [e.g., tetanus toxoid (TT) and formalinized bovine serum albumin (f-BSA)] in the presence of moisture and physiological temperature. Coincorporation of the formaldehyde-interacting amino acid, histidine, strongly inhibits the FMAP. The purpose of this study was to test whether previous solid-state data are applicable toward the stabilization of formalinized antigens encapsulated in poly(lactide- co -glycolide) (PLGA)-based microspheres. Formaldehyde-treated bovine serum albumin (f-BSA) and BSA were selected as a model formalinized protein antigen and a nonformalinized control, respectively. As in the solid state, we found that the FMAP was dominant in the aggregation of f-BSA encapsulated in PLGA 50/50 microspheres, whereas the aggregation mechanism of encapsulated BSA was mostly converted from thiol–disulfide interchange to an acid-catalyzed noncovalent pathway. The lack of noncovalent aggregation in encapsulated f-BSA could be explained by its higher thermodynamic stability after formalinization, which inhibits protein unfolding. Targeting the FMAP, coencapsulation of histidine and trehalose successfully inhibited the aggregation of f-BSA in microspheres. By combining the use of an optimized oil-in-oil (o/o) encapsulation method, coencapsulation of histidine and trehalose, and use of low-acid-content poly( D , L -lactide) (PLA) and poly(ethylene glycol) (PEG) blends, a 2-month continuous release of f-BSA was achieved with the absence of aggregation. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1558–1569, 2001Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34504/1/1106_ftp.pd

Stabilization and Controlled Release of Bovine Serum Albumin Encapsulated in Poly(D, L-lactide) and Poly(ethylene glycol) Microsphere Blends

Purpose . The acidic microclimate in poly(D, L-lactide-co-glycolide) 50/50 microspheres has been previously demonstrated by our group as the primary instability source of encapsulated bovine serum albumin (BSA). The objectives of this study were to stabilize the encapsulated model protein, BSA, and to achieve continuous protein release by using a blend of: slowly degrading poly(D, L-lactide) (PLA), to reduce the production of acidic species during BSA release; and pore-forming poly(ethylene glycol) (PEG), to increase diffusion of BSA and polymer degradation products out of the polymer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41487/1/11095_2004_Article_302758.pd

Determination of water-soluble acid distribution in poly(lactide- co -glycolide)

Determination of the kinetics of water-soluble degradation products inside poly(lactide- co -glycolide) (PLGA) delivery systems during polymer degradation is important to evaluate the polymer microclimate conditions, particularly microclimate pH changes for optimization of encapsulated drug stability. A pre-derivatization high-performance liquid chromatography (HPLC) method was developed for separation and quantification of water-soluble acid impurities and degradation products in PLGA. Thin PLGA films (∼200 Μm) were incubated in PBS/0.02% Tween 80, pH 7.4, for 6 weeks. Water-soluble monomers and oligomers were obtained from polymer films after repeated CHCl 3 /H 2 O extraction and then derivatized into bromophenacyl esters. With the common chromophore, the esters were separated and quantified by HPLC with increased ultraviolet (UV) sensitivity at 254 nm. The total amount of water-soluble acids in the extract was validated by potentiometric titration with tetrabutyl ammonium hydroxide. During the first 3 weeks of incubation of PLGA 50:50 (inherent viscosity = 0.63 dL/g), the principal water-soluble acids in the polymer were glycolic, lactic, and lactoyllactic acids, and an unknown oligomer. After 4 weeks of incubation, a large fraction of higher molecular weight oligomers was observed. Pre-derivatization HPLC can be used to accurately measure water-soluble acid distribution, and may be invaluable to examine the degradation behavior of PLGAs, including the underlying mechanism of polymer microclimate pH development. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:322–331, 2004Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34511/1/10524_ftp.pd

Battle of GLP-1 delivery technologies

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) belong to an important therapeutic class for treatment of type 2 diabetes. Six GLP-1 RAs, each utilizing a unique drug delivery strategy, are now approved by the Food and Drug Administration (FDA) and additional, novel GLP-1 RAs are still under development, making for a crowded marketplace and fierce competition among the manufacturers of these products. As rapid elimination is a major challenge for clinical application of GLP-1 RAs, various half-life extension strategies have been successfully employed including sequential modification, attachment of fatty-acid to peptide, fusion with human serum albu- min, fusion with the fragment crystallizable (Fc) region of a monoclonal antibody, sustained drug delivery sys- tems, and PEGylation. In this review, we discuss the scientific rationale of the various half-life extension strategies used for GLP-1 RA development. By analyzing and comparing different approved GLP-1 RAs and those in development, we focus on assessing how half-life extending strategies impact the pharmacokinetics, pharmacodynamics, safety, patient usability and ultimately, the commercial success of GLP-1 RA products. We also anticipate future GLP-1 RA development trends. Since similar drug delivery strategies are also applied for de- veloping other therapeutic peptides, we expect this case study of GLP-1 RAs will provide generalizable concepts for the rational design of therapeutic peptides products with extended duration of action

Self‐healing encapsulation and controlled release of vaccine antigens from PLGA microparticles delivered by microneedle patches

There is an urgent need to reduce reliance on hypodermic injections for many vaccines to increase vaccination safety and coverage. Alternative approaches include controlled release formulations, which reduce dosing frequencies, and utilizing alternative delivery devices such as microneedle patches (MNPs). This work explores development of controlled release microparticles made of poly (lactic‐co‐glycolic acid) (PLGA) that stably encapsulate various antigens though aqueous active self‐healing encapsulation (ASE). These microparticles are incorporated into rapid‐dissolving MNPs for intradermal vaccination.PLGA microparticles containing Alhydrogel are loaded with antigens separate from microparticle fabrication using ASE. This avoids antigen expsoure to many stressors. The microparticles demonstrate bi‐phasic release, with initial burst of soluble antigen, followed by delayed release of Alhydrogel‐complexed antigen over approximately 2 months in vitro. For delivery, the microparticles are incorporated into MNPs designed with pedestals to extend functional microneedle length. These microneedles readily penetrate skin and rapidly dissolve to deposit microparticles intradermally. Microparticles remain in the tissue for extended residence, with MNP‐induced micropores resealing readily. In animal models, these patches generate robust immune responses that are comparable to conventional administration techniques. This lays the framework for a versatile vaccine delivery system that could be self‐applied with important logistical advantages over hypodermic injections.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147859/1/btm210103-sup-0001-supinfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147859/2/btm210103_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147859/3/btm210103.pd

A Multidimensional Analytical Comparison of Remicade and the Biosimilar Remsima

In April 2016, the Food and Drug Administration approved the first biosimilar monoclonal antibody (mAb) – Inflectra/Remsima (Celltrion) based off the original product Remicade (infliximab, Janssen). Biosimilars promise significant cost savings for patients, but the unavoidable differences between innovator and copycat biologics raise questions regarding product interchangeability. In this study, Remicade and Remsima were examined by native mass spectrometry, ion mobility and quantitative peptide mapping. The levels of oxidation, deamidation and mutation of individual amino acids were remarkably similar. We found different levels of C-terminal truncation, soluble protein aggregates and glycation that all likely have a limited clinical impact. Importantly, we identified over 25 glycoforms for each product and observed glycoform population differences, with afucosylated glycans accounting for 19.7% of Remicade and 13,2% of Remsima glycoforms, which translated into a 2-fold reduction in FcγRIIIa binding for Remsima. While this difference was acknowledged in Remsima regulatory filings, our glycoform analysis and receptor binding results appear to be somewhat different from the published values, likely due to methodological differences between laboratories and improved glycoform identification by our laboratory using a peptide map-based method. Our mass spectrometry based analysis provides rapid and robust analytical information vital for biosimilar development. We have demonstrated the utility of our multiple attribute monitoring workflow using the model mAbs Remicade and Remsima, and have provided a template for analysis of future mAb biosimilars

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival