ACAAI background on Anti-IgE for the treatment of allergic disease:

• The U.S. Food and Drug Administration's (FDA_ Pulmonary-Allergy Drugs Advisory Committee (PADAC) voted unanimously May 15 that the anti-IgE drug omalizumab for injection (trade name Xolair) be approved for the treatment of moderate-to-severe allergic asthma in adults and adolescents.

• Anti-IgE is one of the major breakthroughs in allergy treatment over the past 30 years. It's different from other treatments because it actually stops the allergic reaction before it begins by blocking the IgE antibody, an underlying cause of allergic asthma. It is administered by injection every two to four weeks.

• The May 15 unanimous vote signaled the FDA PADAC Committee's agreement that the benefits of the treatment outweigh any potential risks. Initial FDA briefing reports issued in advance of the May 15 meeting addressed potential risks, including a possible link between anti-IgE and increased incidence on cancer among study participants. Clinical investigators and an independent panel of oncologists who reviewed the study data found no statistically significant link between the treatment and risk of cancer. The clinical data did, however, show strong evidence of effectiveness.

• Other therapies treat the symptoms or they modify the immune system's reaction to specific allergens. For example, allergy shot prescribed after tests that determine whether you're allergic to cats. or ragweed or other allergens. Over time, the shots decrease your body's hypersensitivity and reactions to those allergens. Antihistamines work by blocking the effects of histamines so that allergic symptoms are not triggered in response to contact with allergens.

• Although research continues on anti-IgE for allergic rhinitis and peanut allergy, for now the treatment is approved only for patients age 12 and older with moderate-to-severe allergic asthma. These are patients who will finally get some relief after failing with other treatments, and will find that anti-IgE greatly reduces their reliance on other medications.

• 50 million people have asthma or allergies and many of them either don't have their condition under control or they need to take medications all day long. Allergic asthma is asthma that's triggered by an allergic reaction to something - animal dander, ragweed, grass, dust mites. About 17 million people have asthma; about half of all adult cases are allergic asthma and about 80 percent of pediatric cases are allergic asthma.

• For people who will not be candidates for anti-IgE treatment, many of them could be doing more to control their asthma. Despite advances in asthma prevention, diagnosis and treatment, asthma is still one of the most common chronic diseases, causing 5,000 deaths each year.

• Peak allergy season is approaching and allergies and asthma will keep many people home from work and school. Many asthma sufferers who don't have their disease under control, including many with mild to moderate asthma, will unnecessarily end up in a hospital or emergency room.

FDA ADVISORY COMMITTEE UNANIMOUSLY RECOMMENDS APPROVAL OF XOLAIR

 - Potential First Biologic Treatment for Allergic Asthma Targets Underlying Cause of Disease

Gaithersburg, MD -- May 15, 2003 --Genentech, Inc. (NYSE: DNA), Novartis Pharmaceuticals Corporation, an affiliate of Novartis AG (NYSE: NVS) and Tanox, Inc. (Nasdaq: TNOX) announced today that the U.S. Food and Drug Administration's (FDA) Pulmonary-Allergy Drugs Advisory Committee (PADAC) voted unanimously that Xolair ™ (omalizumab) for injection be approved based on favorable risk-benefit profile for the treatment of moderate-to-severe allergic asthma in adults and adolescents. Xolair represents a novel treatment approach as the first humanized monoclonal antibody developed for the treatment of allergic asthma and the only allergic asthma treatment designed to block the IgE antibody, specifically targeting an underlying cause of allergic asthma. Based on the results of today's advisory committee meeting, the sponsors will conduct further discussion with the FDA regarding product labeling and post-marketing commitments.

In clinical trials of moderate-to-severe patients, Xolair was found to reduce asthma exacerbations (allergic asthma attacks) and enable many patients to reduce or eliminate usage of inhaled corticosteroids. The companies are seeking approval to market Xolair in the United States as a potential maintenance therapy for the prophylaxis of asthma exacerbations and control of asthma symptoms in adults and adolescents (12 years and older) with moderate-to-severe allergic asthma that is inadequately controlled despite the use of inhaled corticosteriods.

"Today's decision is an important milestone for allergic asthma sufferers who cannot manage their condition with the treatments currently available." said Hal Barron, M.D., FACC, vice president, Medical Affairs for Genentech. "If approved, Xolair would be the first biologic therapy for patients with allergic asthma, and the only therapy that specifically targets IgE, an underlying cause of the condition."

Cynthia Hogan, vice president, Respiratory and Dermatology Therapeutic Foundation Franchise for Novartis Pharmaceuticals Corporation added, "We are very pleased with the positive feedback provided by the advisory committee members today. We believe that Xolair can provide benefit to an important population of allergic asthma sufferers, and we look forward to working with the FDA to make Xolair available for patients."

"After many years of development for Xolair, we are delighted with the FDA committee recommendation and the potential of helping the many allergic asthma patients," said Nancy T. Chang, president and chief executive officer for Tanox, Inc.

Xolair is being jointly developed under agreements among Novartis Pharma AG, Genetech, Inc. and Tanox, Inc. The biologics License Application for Xolair was filled in June 2000 and a supplemental data amendment was filed in December 2002. The FDA generally follows the advice of its advisory committee, although it is not bound by these recommendations. A decision by the FDA is expected in late June 2003.

If approved by the FDA, Xolair would be the first IgE blocker and the first biologic therapy for the treatment of moderate-to-severe allergic asthma. Furthermore, it is potentially the first asthma product to be administered every two or four weeks. Xolair is designed specifically to block the IgE antibody, a key underlying cause of allergic asthma. When an allergen (e.g., dust, mold, pollen) interacts with (cross-links) IgE bound to mast cells in the human immune system, these cells release inflammatory chemicals such as histamine and leukotriens that lead to the inflammation and bronchial constriction of allergic asthma. Decreasing the amount of IgE bound to mast cells can disrupt the release of these chemical mediators that cause the clinical symptoms of allergic asthma.

Xolair Clinical Trial Results

The advisory committee's discussions focused on data from two 52-week pivotal Phase III clinical trials with 1,071 allergic asthma patients, as well as data from several supportive safety and efficacy studies. The pivotal trials were designed to investigate the dual benefit of reduction in asthma exacerbations and reduction in the dosage of inhaled corticosteriods. Patients treated with Xolair showed significant improvements in asthma exacerbations and symptoms, and most patients reduced their use of steroids and rescue bronchodilators.

In clinical trials when used as an add-on therapy to inhaled corticosteriods, Xolair was found to reduce exacerbations by approximately 50 percent. Additionally, the average dose of inhaled corticosteriods in patients taking Xolair in the teo pivotal trials was reduced by 83 percent and 75 percent respectively, compared to 50 percent in the placebo groups. Steroid use was discontinued in 40-43 percent of patients in the Xolair groups compared to 19 percent in the placebo groups.

The expanded safety database submitted to the FDA includes clinical data from more than 6,000 patients, of which approximately 4,200 patients have been treated with Xolair. In clinical trials, Xolair treatment was generally well tolerated and the frequency of reported adverse events was comparable between Xolair-treated and control groups. The most frequently observed adverse events included viral infections, sinusitis, upper respiratory infection and headache. Serious adverse events were infrequent and of similar incidence in both the Xolair and control groups. The final efficacy and safety description in the product labeling will be determined by the FDA.

About Allergic Asthma

Allergic asthma is a chronic inflammatory disorder of the airways in which exposure to an allergen (e.g., dust, mold, pollen) triggers an allergic cascade, resulting in airway inflammation and obstruction. Asthma results in more then two million emergency room visits and more then 5,000 deaths in the United States each year, according to the Center for Disease Control and Prevention's National Center for Health Statistics.