SurModics Inc (SRDX)

[Democritus_of_Abdera]

Genentech had examined the value of using controlled-release microspheres for intra-vitreal antibody administration in the late 1990’s. They apparently concluded that there was no advantage of sustained release formulations over direct injection; the long half-life of IgG in the vitreous being sufficient to prolong its therapeutic availability. Perhaps the experience gained in these studies has biased Genetech against seeking a collaboration with SRDX.

See:

Mordenti J, Thomsen K, Licko V, Berleau L, Kahn JW, Cuthbertson RA, Duenas ET, Ryan AM, Schofield C, Berger TW, Meng YG, Cleland J. (1999). Intraocular pharmacokinetics and safety of a humanized monoclonal antibody in rabbits after intravitreal administration of a solution or a PLGA microsphere formulation. Toxicol Sci. 1999 Nov;52(1):101-6.

Department of Experimental Therapeutics, Genentech, Inc., South San Francisco,
California 94080, USA. [e-mail]

“Poly(lactic-co-glycolic) acid (PLGA) bioresorbable microspheres are used for controlled-release drug delivery and are particularly promising for ocular indications. The objective of the current study was to evaluate the pharmacokinetics and safety of a recombinant human monoclonal antibody (rhuMAb HER2) in rabbits after bolus intravitreal administration of a solution or a PLGA-microsphere formulation. ....”

“This antibody was selected to serve as a model compound for evaluation of in vitro and in vivo release kinetics of a large molecular weight protein (~148 kD) from PLGA microspheres, rhuMAb HER2 was encapsulated in PLGA using a patented 2-step, spray freeze-drying microencapsulation process (Johnson et al., 1996)....”

“Finally, rhuMab HER2 was cleared slowly from the vitreous compartment; the PLGA formulation did not offer any pharmacokinetic advantage over the solution formulation. The long terminal half-life (~5.6 days) suggests that injections of a therapeutic antibody in solution every 1 or 2 months may provide adequate concentrations without further formulation work....”