Replies to post #266 on Biotech Values

[isolution]

Not dissmissive, just physiology
About Eyetech and Genentech. First, concerning the wash out effect, let me cite 2 articles. In the review "Drug delivery for posterior segment Eye disease " IOVS 2000, Geroski et al cited "An intravitreal injection provides the most direct approach to delivering drugs to the vitreous of the posterior segment, and therapeutic tissue drug levels can be achieved (...)Repeat injections are frequently required (...) Further, drugs injected directly into the vitreous are rapidly eliminated" and in another review "Challenge of intraocular drug delivery" Europ. Pharma. Rev 2001, Behar-Cohen et al cited "The simpliest mean of bypassing physiological and anatomical barriers and achieving high concentrations of drugs within the eye is to attempt their introduction through direct intraocular administration (...) In clinical practice, intraocular injections frequently have to be repeated in order to maintain therapeutically drug concentration for a desired period of time (...)Because of the rapid clearance of drug from the eye and the potential induction of irreversible toxicity to the internal tissues, new intraocular drug delivery systems are being intensively investigated".
This could be why, beside conducting phase III where we have seen these drugs being effective and having enough time to bind to the target sites, Eyetech is investigating new delivery system (see "Controlled delivery of the anti-VEGF Aptamer EYE001 with PLGA microspheres" Carrasquillo et al IOVS 2003. They will need some kind of improved sustain release to improve their (good) results.