• Glucocerebrosidase
• Pipeline Products

We are developing other recombinant therapeutic proteins to be expressed by our ProCellEx™ protein expression system, with an emphasis on treatments for which there are large, established pharmaceutical markets and where our proprietary protein expression system enables us to develop and commercialize recombinant proteins that are patent-protected and therapeutically equivalent or superior to the existing treatments. We select additional therapeutic candidates for development by testing candidates in-house and through collaborations with academic partners. We have identified several product candidates oriented towards specialty disease and therapeutic market segments, including treatments for Fabry disease and female infertility. In addition, we are conducting initial research to evaluate potential programs in the fields of monoclonal antibodies, cytokines and vaccines. We plan to file an investigational new drug application (IND) with the FDA with respect to at least one additional product during 2008. In addition, we are developing a new method for delivering active recombinant proteins systemically through oral administration of transgenic plant cells expressing such biotherapeutic proteins.

PRX-102

We are developing a proprietary alpha Galactosidase enzyme, currently titled PRX-102, which is a therapeutic enzyme for the treatment of Fabry disease, a rare genetic lysosomal storage disorder in humans, the symptoms of which involve the accumulation of lipids in the cells of the kidneys, heart and other organs. Fabry disease affects more than 8,000 people globally. We believe that the treatment of Fabry disease is a specialty clinical niche with the potential for high growth. Currently there are two drugs available on the market to treat Fabry disease. Fabrazyme, made by Genzyme, was approved for the treatment of Fabry disease in the European Union in 2001 and the United States in 2003. Genzyme reported $359 million in worldwide sales of Fabrazyme in 2006. The other approved drug for the treatment of Fabry disease in the European Union is Replagal, which is sold by Shire plc. Shire reported $118 million in sales of Replagal in 2006.

We are currently in the research phase of the development of PRX-102 and expect to initiate animal evaluation testing in the second half of 2007. As was the case in our development of prGCD, our development of PRX-102 involves the expression by our proprietary protein expression system of a naturally occurring enzyme to be used in enzyme replacement therapy for the treatment of Fabry disease. Based on our experience with prGCD and the experience of other companies developing enzyme replacement therapies for Fabry disease, we have reason to believe that, if favorable data is accumulated in preclinical and phase I clinical trials, the FDA may allow us to proceed directly with a pivotal phase III clinical trial without the need to complete a phase II clinical trial. However, there can be no assurance that we will initiate preclinical or phase I clinical trials and if we do, that such trials will result in favorable data. In addition, there can be no assurance that the FDA will allow us to proceed directly with a phase III clinical trial after completion of a phase I clinical trial.

PRX-111

We are developing two variants of Follicle Stimulating Hormone (FSH), a human fertility hormone targeted at the female infertility market, one of which is in collaboration with a third party. The three most active companies in the market for FSH biotherapeutic proteins are Merck Serono S.A., Organon, a subsidiary of Akzo Nobel N.V., and Ferring Pharmaceuticals, a private company. Merck Serono reported aggregate worldwide sales equal to approximately $523 million for 2006 of its FSH protein, Gonal-f®, and based upon information disclosed by Akzo Nobel, Organon had worldwide sales of its FSH protein, Purgenon, of approximately $591 million in 2006. To date, we believe that our in vitro experiments with these hormones have demonstrated equivalent to superior biochemical and cellular results when compared to the currently marketed biotherapeutic hormones used in approved female infertility treatments. We are currently performing additional in vivo animal research to evaluate the advantages of our FSH variants under development compared to the therapeutic proteins currently marketed to treat female infertility.

Acetylcholinesterase

In January 2007, we entered into an agreement in principle with the Yissum Research and Development Company, the technology transfer arm of the Hebrew University of Jerusalem, Israel, and with the Boyce Thompson Institute, Inc., which is affiliated with Cornell University, pursuant to which we are developing a proprietary plant cell-based acetylcholinesterase (AChE) and its molecular variants for the use in several therapeutic and prophylactic indications, as well as in a biodefense program. Pursuant to the terms of the agreement in principle, which is subject to final agreement, we expect to license the technology underlying the developed acetylcholinesterase from Yissum Research/Hebrew University and Boyce Thompson. We are currently performing research in order to evaluate the potential for the developed acetylcholinesterase and its variants, for various therapeutic fields. To date, our in vitro experiments have shown that the acetylcholinesterase expressed in our ProCellEx™ expression system demonstrates promising biological activity on biochemical and cellular levels.