Media/Investor Contact:

Anne Erickson

Executive Director

Halozyme Therapeutics

858-704-8264

aerickson@halozyme.com

Presented data from two Phase 1 studies which indicate pegylated rHuPH20 (PEGPH20) can favorably alter the tumor stroma of hyaluronin-rich tumors.

Began a Phase 2 clinical trial with PEGPH20 in patients with advanced pancreatic cancer to study the safety, tolerability, and efficacy of gemcitabine (a chemotherapeutic) plus PEGPH20 compared to gemcitabine plus placebo.

Announced positive results from two Phase 2 clinical trials of ultrafast Analog-PH20 (analog insulin + rHuPH20) in patients with Type 1 and Type 2 diabetes. Both trials met their primary endpoint of non-inferiority of A1C compared to the insulin analog comparator, with superior reductions in post-prandial glucose excursions in the Analog-PH20 arms. The data from the trials indicate that, compared to insulin analog alone, Analog-PH20 use resulted in a greater than 50% increase in the proportion of patients able to consistently achieve the American Association of Clinical Endocrinologists guideline targets for post-prandial glucose at both one and two hours after meals.

Announced positive results from a Phase 1b trial indicating that pre-administration of 150 units of rHuPH20 prior to the start of three days of NovoLog^® insulin aspart pump infusion therapy led to consistent insulin exposure over the infusion set life and superior glucose control following meals.

Presented data from a Phase 1/2 trial of HTI-501 (an investigational, conditionally active recombinant human cathepsin) in female patients with fibrosclerotic panniculopathy, more commonly known as cellulite. No serious or severe adverse events were reported in the ongoing Phase 1 portion of the trial. These data support commencement of the Phase 2 trial.

Announced that Roche has submitted a Line Extension Application to the EMA for subcutaneous Herceptin to treat patients with HER2-positive breast cancer. Herceptin SC uses Halozyme’s Enhanze™ technology which enables the injection of a large volume of medication to be administered subcutaneously (under the skin) and may result in faster administration times versus intravenously (IV) administered Herceptin.

Announced positive results from Roche’s Phase 3 trial that showed women with HER-2 positive early breast cancer who received Herceptin SC experienced comparable results to Herceptin given as an IV infusion. The full data set from this trial is scheduled to be presented by Roche at the European Breast Cancer Conference (EBCC) on March 23rd in Vienna, Austria.

Baxter presented long-term clinical data on HyQ (Immune Globulin + rHuPH20), proposed brand name HyQvia, indicating the investigational therapy continued to demonstrate favorable safety and activity during the extension phase.

Announced positive top-line data from a Phase 2 study that suggest rHuPH20 enhances the delivery and absorption of Cinryze^® (C1 esterase inhibitor [human]) in subjects with hereditary angioedema.

Revenues for the fourth quarter of 2011 were $2.4 million, compared to $3.6 million for the fourth quarter of 2010. Revenues in the fourth quarter of 2011 also consisted of the amortization of upfront payments received from Baxter and Roche of $0.6 million and research and development reimbursements from Baxter and Roche of $1.2 million.

Research and development expenses for the fourth quarter of 2011 were $14.9 million, compared with $15.9 million for the fourth quarter of 2010, primarily due to a decrease in clinical trial activities, partially offset by an increase in manufacturing activities.

Selling, general and administrative (SG&A) expenses for the fourth quarter of 2011 were $5.9 million, compared to $4.6 million for the fourth quarter of 2010. The increase for SG&A results from higher marketing and market research expenses during the quarter.

Cash and cash equivalents were $52.8 million as of December 31, 2011, compared with $83.3 million as of December 31, 2010 and $66.3 million as of September 30, 2011. Net cash used in the fourth quarter of 2011 was approximately $13.5 million. In February, the Company raised approximately $82 million through an underwritten public offering of 7,820,000 shares of its common stock.

For 2012, operating expenses are expected to grow at a mid-teens growth rate, compared to 2011, due to increased costs in manufacturing, clinical trials, marketing, and reimbursable partner-related costs. Excluding a recent financing, with net proceeds of approximately $82 million, the Company expects net cash burn to be between $50 and $55 million.

24^th Annual Roth Conference in Dana Point on March 14, 2012 at 12:30 p.m. ET/9:30 a.m. PT. Kurt Gustafson, Chief Financial Officer of Halozyme Therapeutics, will provide a corporate overview.

Barclays Capital 2012 Global Healthcare Conference in Miami on March 14, 2012 at 4:15 p.m. ET/1:15 p.m. PT. Gregory I. Frost, Ph.D., President and Chief Executive Officer of Halozyme Therapeutics, will provide a corporate overview.

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