Evaluating a new Microsphere-based Controlled-Release Delivery System

On Drug Delivery, July 2017

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In recent years, therapeutic proteins, such as vaccines, antigens, and hormones, have made significant advances using sophisticated biotechnological techniques like recombinant technology.  However, the mode of administration has been a limiting factor.  Frequent injections and low patient acceptability make even the simplest parenteral administration of these drugs problematic, thus there is a need for new delivery systems to deliver these drugs more effectively.  Oral delivery of proteins and peptides has long been hailed the holy grail of drug delivery for obvious reasons (i.e. ease and cost of administration, product shelf-life, patient compliance and acceptability) but has remained a challenge due to enzymatic degradation in the gastro-intestinal (GI) tract and low bioavailability.

Here we evaluate a microsphere based controlled-release delivery system that appears to have promising results.  PolyMicrospheres successfully developed an oral delivery system for a recombinant vaccine that resulted in an antibody titre count three times higher than parenteral delivery.  The microsphere based delivery system greatly enhanced immunity: 100% survival of mice against the toxin and 88% survival of rabbits against the live bacterial spores, compared with 0% survival with the aqueous recombinant protective antigen (RPA) system.

This microsphere-based delivery technology can be easily translated to the oral delivery of other proteins, peptides, vaccines and hormones.


A third generation Recombinant Vaccine-Delivery System for
Single-dose Subcutaneous Administration

Journal of Drug Discovery, Development and Delivery, July 2017

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PolyMicrospheres successfully developed Microsphere-based Delivery Systems (MDS) for controlled-release delivery of a recombinant vaccine via single-dose subcutaneous administration.  The MDS formulations were tested against the current standard of care, an aqueous Recombinant Protective Antigen (RPA) vaccine.  The MDS, on a single-subcutaneous dose, greatly enhanced immunity: 100% protection against anthrax-toxin challenge in mice, compared to <13% protected by the aqueous RPA vaccine system and 0% in the non-immunized control group.  Additionally, rabbits immunized with selected MDS, on a single-subcutaneous dose, showed 100% protection against live anthrax-spores, compared to <17% in the aqueous RPA vaccine system and 0% in the non-immunized control group.

This single-dose administration can simplify the logistics of mass immunization, reducing the cost of the vaccine and its administration for both civilian and military populations.

3rd-generation Intranasal Anthrax Vaccine-Delivery System

On Drug Delivery, April 2017

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PolyMicrospheres successfully developed microsphere-based delivery systems (MDS) for controlled and pulsed-release delivery of a recombinant vaccine via intranasal immunisation.  The MDS formulations were tested against the current standard of care, an aqueous Recombinant Protective Antigen (RPA) vaccine.  The MDS produced extremely high antibody titres (over 150,000) in mice after 65 days of immunisation compared with the aqueous RPA vaccine system (at 15,900).  Selected MDS systems were challenged with anthrax toxin.  The MDS, on two intranasal doses, showed 100% protection against anthrax toxin challenge in mice, compared to <17% in the aqueous RPA vaccine system and 0% in the non-immunised control group.

The platform technology of this intranasal delivery system is also suitable for other human and veterinary vaccines including simultaneous intranasal delivery of multiple immunogens.