Physicochemical and Preclinical Evaluation of a Novel Buccal Measles Vaccine.

The aim of this study is to develop an orally disintegrating film (ODF) containing a microparticulate measles vaccine formulation for buccal delivery. The measles vaccine microparticles were made with biocompatible and biodegradable bovine serum albumin (BSA) and processed by spray drying. These vaccine microparticles were incorporated in the ODF, consisting of Lycoat RS720®, Neosorb P60W® and Tween 80. The yield of the microparticles was approximately 85-95%, w/w. The mean size of the vaccine microparticles was 3.65 ± 1.89 µm and had a slightly negative surface charge of 32.65 ± 2.4 mV. The vaccine particles were nontoxic to normal cells at high concentrations (500 µg/2.5 × 105 cells) of vaccine particles. There was a significant induction of innate immune response by vaccine microparticles which was observed in vitro when compared to blank microparticles (P < 0.05). The vaccine microparticles also significantly increased the antigen presentation and co-stimulatory molecules expression on antigen presenting cells, which is a prerequisite for Th1 and Th2 immune responses. When the ODF vaccine formulation was dosed in juvenile pigs, significantly higher antibody titers were observed after week 2, with a significant increase at week 4 and plateauing through week 6 comparative to naïve predose titers. The results suggest that the ODF measles vaccine formulation is a viable dosage form alternative to noninvasive immunization that may increase patient compliance and commercial distribution.

Development of ß-cyclodextrin-based sustained release microparticles for oral insulin delivery.

Polymeric microparticles have been previously demonstrated to deliver various therapeutic agents efficiently to targeted regions by protecting the drug from harsh gastric milieu of the gastrointestinal tract. In this study, we investigated the hypoglycemic effect of ß-cyclodextrin polymeric insulin microparticles in diabetic rats via the oral route of administration. ß-cyclodextrin microparticles were prepared by a unique one-step spray-drying technique and stabilized by incorporating enteric retardant polymers in the formulation. The insulin-loaded microparticles had a mean size of 0.8 ± 0.25 µm with a zeta potential of 3.57 + 0.62 mV. As seen with the chromatographic analysis, the drug content in the microparticles was determined to be 94.9 ± 2.77%. RAW macrophage cells showed greater than 80% viability after 24 h of incubation with the insulin and blank microparticles. For the in vitro release study, the microparticles were able to protect the insulin in gastric fluid where no significant release was detected, followed by only 50% release in intestinal fluid for the first 8 h of the study. This was seen to correlate with the in vivo data where 50% glucose inhibition was seen after 8 h of oral administration in diabetic rats. This data suggest that the oral insulin microparticles were able to reduce glucose levels in disease conditions and would be a favorable route of administration to patients as an alternative to daily subcutaneous injections.

A novel microparticulate vaccine for melanoma cancer using transdermal delivery.

In this study, we formulated a microparticulate melanoma cancer vaccine via the transdermal route. The vaccine was delivered using microneedle-based Dermaroller® which is available for cosmetic purposes. Unlike subcutaneous injections, administration using microneedles is painless and in general can increase the permeability of many compounds ranging in size from small molecules to proteins and microparticles that do not normally penetrate the skin. The vaccine microparticles were taken up by the antigen presenting cells which demonstrated a strong IgG titre level of 930 ug/mL in serum samples. The formulation increased the immunogenicity of the vaccine by incorporating the antigen into an albumin matrix having a size range of around 0.63-1.4 µm which acted as a synthetic adjuvant. The animals were vaccinated with 1 prime and 4 booster doses administered every 14 days over 8 weeks duration, followed by challenge with live tumour cells which showed protection after transdermal vaccination.

Considerations for Buffering Agent Selection for Frozen rAAV2 Mediated Gene Therapy Products.

The buffering component selection is a key criterion for the formulation development process for biopharmaceuticals. This decision for recombinant adeno-associated virus (rAAV) mediated gene therapies is receiving special attention due to their rise in clinical trials which may require high concentration, frozen supply chain, and direct delivery to eye and central nervous system related sites. In the present study, we investigate the impact of rates of freezing and thawing on rAAV2 as a model serotype. It was observed that slow rate of thawing impacts rAAV2 colloidal stability in Phosphate based buffering system. Our pre-formulation workflow suggests that rAAV2 has maximum aggregation propensity between pH of 5.5 to 6.5. Thus, the overlap of maximum aggregation propensity pH range with acidic pH shift in Phosphate based buffering system during freezing and thawing appears to be responsible for 42-75% concentration drop noticed for rAAV2. This impact appears to be fully mitigated upon replacement of Phosphate based buffering system with an alternate buffer system such as Tris. The results reported in this study highlight associated risks and provide preliminary guidance on handling of early stage frozen rAAV mediated gene therapies.

Thin-film freeze-drying of a bivalent Norovirus vaccine while maintaining the potency of both antigens.

A bivalent Norovirus vaccine candidate has been developed that contains Norovirus strain GI.1 Norwalk-virus like particles (VLP) and strain GII.4 Consensus VLP adsorbed on aluminum (oxy)hydroxide. The Norwalk and Consensus antigens have different stability profiles, making it challenging to prepare a dry powder form of the Norovirus vaccine while maintaining the potency of both antigens. In the present study, we tested the feasibility of converting the vaccine from a liquid suspension to dry powders by thin-film freeze-drying (TFFD). With the proper amount of trehalose and/or sucrose as cryoprotectant (i.e. sucrose alone at 4.55% or 5.55%, w/v, or trehalose at 3-4% with 0.55% of sucrose), TFFD can be applied to successfully convert the Norovirus vaccine candidate into dry powders without causing antigen loss or particle aggregation, while maintaining the relative potency of both antigens within a specified acceptable range. In an accelerated stability study, the potency of the antigens was also maintained in the specified acceptable range after the dry powders prepared by TFFD in the presence of 5.55% (w/v) of sucrose were stored for eight weeks at 40 °C, 75% relative humidity. It is concluded that it is feasible to apply TFFD to convert the Norovirus vaccine from a liquid suspension to stable dry powders.

Enhanced bioavailability of orally administered antisense oligonucleotide to nuclear factor kappa B mRNA after microencapsulation with albumin.

Antisense molecules that pertain to ribonucleic acid (RNA) and complementary to the messenger RNA (mRNA) are produced by transcription of a given gene. Antisense oligonucleotides have emerged as potential gene-specific therapeutic agents that are currently undergoing evaluation in clinical trials for a variety of diseases. When administered orally, antisense oligionucleotides have poor bioavailability as they are rapidly degraded by the acid in the stomach and by the enzymes in the intestine. Therefore, the enhancement of bioavailability after oral administration is highly desirable. This article shows the enhanced bioavailability of antisense oligonucleotides that targets nuclear factor kappa B (NF-κB) mRNA after encapsulating in an inert, biodegradable albumin polymer matrix that was administered via the oral route into a rat model. The bioavailability of the antisense oligonucleotides to NF-κB in microencapsulated form was compared to the solution form of the drug upon oral administration. The solution form had a low bioavailability of 9%, whereas the bioavailability for the microencapsulated form of the drug increased up to 70%. Moreover, the other pharmacokinetic parameters including half-life (t1/2) and volume of distribution (Vd) increased for the microencapsulated form compared to the solution form of the drug.

Oral delivery of microparticles containing plasmid DNA encoding hepatitis-B surface antigen.

The role of albumin-based chitosan microparticles on enhancing immune response of plasmid DNA (pDNA) to hepatitis-B surface antigen (HBsAg) vaccine after oral administration was investigated in mice. The pDNA encoding HBsAg was entrapped in albumin microparticles using a one-step spray drying technique optimized in our laboratory. The encapsulated particles were also characterized in vitro for their shape, size, encapsulation efficiency, content, and stability. Albumin microparticles could protect the DNA from nuclease degradation as confirmed in our agarose gel study. Further immune modulating effect was studied in our formulation by measuring IgG antibodies in serum as well as IgA antibodies in fecal extracts. The mice were immunized with a prime dose of 100 µg of pDNA in microparticle formulations with and without interleukins biweekly until week 7 followed by a booster dose of equivalent strength on week 33 to compare the response with the subcutaneous group. The oral immunization with the pDNA to HBsAg microparticles gave significantly higher titer level of both sIgA and IgG at week 9 and 34, respectively, in oral vaccine with interleukins group when compared with the subcutaneous group. Thus, we observed an augmentation of both humoral and cellular immune responses for prolonged periods after immunization.

Oral microparticulate vaccine for melanoma using M-cell targeting.

Cancer vaccines are limited in their use, because of their inability to mount a robust anti-tumor immune response. Thus, targeting M-cells in the small intestine, which are responsible for entry of many pathogens, will be an attractive way to elicit a strong immune response toward particulate antigens. Therefore, in the present investigation, we demonstrated that efficient oral vaccination against melanoma antigens could be accomplished by incorporating the antigens in an albumin-based microparticle with a ligand AAL (Aleuria aurantia lectin) targeted specifically to M-cells. The oral microparticulate vaccine effectively protected the mice from subcutaneous challenge with tumor cells in prophylactic settings. The animals were vaccinated with antigen microparticles having a size range of around 1-1.25 µm where one prime and four booster doses were administered every 14 days over 10 weeks of duration, followed by challenge with live tumor cells, which showed complete tumor protection after oral vaccination. With the inclusion of ligand in the microparticles, we observed significantly higher IgG titers (1565 µg/mL) as compared to the microparticle formulations without AAL (872 µg/mL). This data suggests that ligand loaded microparticles may have the potential to target antigens to M-cells for an efficient oral vaccination.