XOMA'S Neuprex Receives Orphan Drug Designation for the Treatment of Severe Meningococcal Disease.

BERKELEY, Calif.--(BW HealthWire)--June 23, 1998--XOMA Corporation (NASDAQ:XOMA) announced that its Neuprex(tm) product for the treatment of severe meningococcal disease has been designated an Orphan Drug under the Orphan Drug Act by the US Food and Drug Administration (FDA). Orphan Drug designation will provide XOMA a seven-year exclusive US marketing period upon FDA approval of the product, and certain additional financial and tax benefits.

"We are pleased that Neuprex(tm) has gained Orphan Drug status in this indication." said Jack Castello, president, chairman and CEO of XOMA Corporation. "The FDA earlier granted a Subpart E designation that allowed us to go directly to a pivotal Phase III trial in meningococcemia. XOMA is currently preparing components of the BLA (Biologics License Application) so that we can submit it to the FDA as soon as we complete the trial. We are working hard to expedite the regulatory review of Neuprex(tm) for this life-threatening children's disease."

XOMA has already enrolled 225 patients at 24 US and UK pediatric hospital centers in its two-year Phase III trial in severe meningococcemia. In this double-blinded trial, patients receive Neuprex(tm) or placebo intravenously; all patients receive the same standard of intensive supportive care. The primary endpoint is reduced mortality; secondary endpoints include reducing morbidities such as amputations or neurological damage. XOMA plans to complete Phase III enrollment by the end of 1998 and is preparing for possible US and European regulatory submissions in 1999.

Meningococcemia (also called meningococcal septicemia) is a deadly infectious disease that occurs when the gram-negative bacteria Neisseria meningitidis (which also cause meningitis) invade a victim's bloodstream. The infecting bacteria can trigger an overwhelming systemic inflammatory reaction. Within hours, an infected child can pass from flu-like symptoms, high fever and a distinctive purple rash to shock, cardiovascular collapse, multiple organ failure and death. The reported mortality rate for children is 20% or more, with a similar number of survivors suffering amputations of extremities or permanent neurological damage.

Neuprex(tm) is an injectable formulation of a genetically-engineered version of a defense protein found in human white blood cells that kills and neutralizes infecting bacteria. It can therefore halt the deadly inflammatory reaction triggered by the bacteria and return the patient to a more normal physiological state. In an open-label Phase II study (published in The Lancet, November, 1997) 26 meningococcemia patients were treated with Neuprex(tm); only one died. That 3.8% case-fatality rate compares to a recent 20% historical mortality rate in comparable patients at the same centers. Treated patients also did better on the Pediatric Overall Performance Category Scale, which evaluates amputations and neurological damage. In August 1996, the FDA granted Neuprexo a Subpart E designation, which is meant to expedite the development, evaluation and marketing of new therapies for life-threatening illnesses.

Neuprex(tm) (rBPI-21), XOMA's lead BPI-derived product, is in the clinic in several indications in addition to the meningococcemia pivotal trial. A 1650-patient Phase III trial, initiated late in 1997, is testing Neuprex(tm) to prevent pulmonary complications in trauma patients suffering severe blood loss. Earlier phase Neuprex(tm) clinical studies target infectious complications of liver surgery (partial hepatectomy), intra-abdominal infections, and lung infections (including antibiotic-resistant infections) in cystic fibrosis patients.

XOMA's other BPI-derived products include I-PREX(tm), a topical ophthalmic formulation of rBPI-21, and Mycoprex(tm), an antifungal peptide product.

XOMA Corporation develops and manufactures genetically-engineered protein, peptide and monoclonal antibody pharmaceuticals. XOMA's medical targets include infections and infectious complications, and immunologic disorders. The company is focused on developing products from BPI (bactericidal/permeability-increasing protein), a host-defense protein found in human neutrophils. BPI was discovered by Drs. Peter Elsbach and Jerrold Weiss at the New York University School of Medicine with which XOMA has collaborated since 1991 to apply BPI-related research to commercial development of pharmaceuticals.

Statements made in this press release relating to the timing of clinical trials and other aspects of product development and regulatory approvals, or that otherwise relate to future periods, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These statements are based on assumptions which may not prove accurate. Actual results could differ materially from those anticipated due to certain risks inherent in the biotechnology industry as well as for companies engaged in the development of new products in a regulated market. These risks, including those related to the results of pending or future clinical trials, changes in the status of the company's collaborative relationships and actions by the U.S. Food and Drug Administration or the U.S. Patent and Trademark Office, are discussed in the company's most recent annual report on Form 10-K and in other SEC filings. Such risks should be considered carefully in evaluating XOMA's prospects.

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