SAN DIEGO, May 19, 2008 /PRNewswire-FirstCall via COMTEX/ ----Halozyme Therapeutics, Inc. (Nasdaq: HALO), a biopharmaceutical company developing and commercializing products targeting the extracellular matrix ("Matrix"), today announced the presentation of new pre-clinical findings on the controlled modification of the Matrix with HTI-501 at the European Society for Dermatological Research (ESDR) and Japanese Society for Investigative Dermatology (JSID).

HTI-501 is a new recombinant human lysosomal proteinase under development at Halozyme that could provide an effective dermatologic treatment by targeting and degrading the fibrous components of the Matrix in a highly controlled fashion. This Matrix targeting new molecular entity is being explored as a potential solution for therapeutic, as well as aesthetic, dermatology indications for which surgery may be impractical, such as cellulite and certain forms of scarring.

HTI-501 works by a process called enzymatic subscision, which involves degradation of fibrous septae (or cords) in a controllable and predictable manner to release skin tissue from the fibrous cords and smooth out the surface contour, which could be especially beneficial in aesthetic dermatology indications. Other proteinases such as collagenases are not generally feasible therapies for aesthetic dermatology, due to their persistent degradation of surrounding tissue that may create safety concerns or require use of sub-potent dosing regimens. As a strictly pH-dependent enzyme, HTI-501 may be capable of exerting its activity in a tightly regulated fashion.

 Key findings were as follows: -- HTI-501 was identified as a member
   of the lysosomal proteinase family capable of degrading insoluble collagen in vitro at pH 5-6, but catalytically inactive
   at physiologic pH of 7.4. -- By injection of pH indicators of increasing buffer strength, the study established that temporal-spatial
   pH control of the extracellular environment from 1-20 minutes post injection could be achieved. -- The efficacy of HTI-501
   on fibrous septae in rodent and porcine models was established by release of hydroxyl-proline and histologic evaluation in
   comparison with bacterial collagenase. -- HTI-501 administration resulted in significant hydroxyproline release at pH 5 compared
   to bacterial collagenase, but not at pH 7.4. Importantly, skin interstitial pH returned to neutrality within 20 minutes of
   the administration of HTI-501. 

"Due to strict pH dependence for enzyme activity, lysosomal proteinases have been largely neglected as potential therapeutic proteins due to their inability to digest proteins outside the lysosomal compartment in the cell," said Gilbert Keller, PhD, Halozyme's Technical Leader in Dermatology. "By bringing this intracellular environment to the extracellular matrix in a temporal fashion, our platform for controlled modulation of the dermal matrix may provide a novel mechanism for tightly controlled pharmacologic subscision of collagenous interstitial matrix. Additional pre-clinical studies are continuing on our lead candidate, HTI-501."

About Halozyme Therapeutics, Inc.

Halozyme is a biopharmaceutical company developing and commercializing products targeting the extracellular matrix for the drug delivery, oncology and dermatology markets. The company's portfolio of products and product candidates is based on intellectual property covering the family of human enzymes known as hyaluronidases. The company's Enhanze(TM) Technology is a novel drug delivery platform designed to increase the absorption and dispersion of biologics. Its key partnerships are with Roche to apply Enhanze Technology to Roche's biological therapeutic compounds for up to 13 targets and with Baxter to apply Enhanze Technology to Baxter's biological therapeutic compound, GAMMAGARD LIQUID 10%. In addition, the company has received FDA approval for two products: Cumulase(R), for use in in-vitro fertilization, and HYLENEX, for use as an adjuvant to increase the absorption and dispersion of other injected drugs and fluids. HYLENEX is partnered with Baxter International Inc. The Company also has a number of different enzymes in its portfolio that are targeting significant areas of unmet need.

Safe Harbor Statement

In addition to historical information, the statements set forth above include forward-looking statements (including, without limitation, statements concerning the pre-clinical results of the company's HTI-501 enzyme program) that involve risk and uncertainties that could cause actual results to differ materially from those in the forward-looking statements. The forward-looking statements are also identified through use of the words "believe," "enable," "may," "will," "could," "intends," "estimate," "anticipate," "plan," "predict," "probable," "potential," "possible," "should," "continue," and other words of similar meaning. Actual results could differ materially from the expectations contained in forward-looking statements as a result of several factors, including regulatory approval requirements and competitive conditions. These and other factors that may result in differences are discussed in greater detail in the company's reports on Forms 10-K, 10-Q, and other filings with the Securities and Exchange Commission.

 Halozyme Contact Media Contacts Robert H. Uhl Karen Sparks / Joleen Schultz Senior Director, Investor Relations
   Mentus (858) 704-8264 (858) 455-5500, x275/x215 ruhl@halozyme.com karen@mentus.com jschultz@mentus.com 

SOURCE Halozyme Therapeutics, Inc.

http://www.halozyme.com/ 

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