Omalizumab: anti-IgE monoclonal antibody E25, E25, humanised anti-IgE MAb, IGE 025, monoclonal antibody E25, Olizumab, Xolair, rhuMAb-E25.

UNLABELLED: Omalizumab [anti-IgE monoclonal antibody E25, E25, humanised anti-IgE MAb, IGE 025, monoclonal antibody E25, olizumab, rhuMAb-E25, Xolair] is a chimeric monoclonal antibody. It binds specifically to the Cepsilon3 domain of immunoglobulin E (IgE). Cepsilon3 is the site of high-affinity IgE receptor binding. IgE plays a major role in allergic disease by causing the release of histamine and other inflammatory mediators from mast cells. Omalizumab binds to and neutralises circulating IgE by preventing IgE from binding to its high-affinity mast-cell receptor. In addition, omalizumab does not bind to or induce histamine release from basophils, nor does it bind to or recognise IgG. The immune complexes formed between IgE and omalizumab in vivo are relatively small (molecular weight <1 million) and are therefore unlikely to cause organ damage. COLLABORATION BETWEEN GENETECH NOVARTIS AND TANOX: omalizumab is very similar to the Tanox product CGP 51901. Genentech (Roche), Novartis and Tanox (formerly Tanox Biosystems) were developing both antibodies in phase II studies, with an agreement to collaborate on phase III development of the most promising one. The Genentech product, omalizumab, was selected for further development. Tanox has marketing rights to the drug in some Asian markets. Novartis and Genentech have marketing rights in the USA. Roche has an option to participate in the commercialisation of omalizumab and other anti-IgE products of the collaboration in Japan and Europe. Roche may exercise this option if specific events relating to commercialisation of the product occur; Roche has waived this option for omalizumab in Japan. If Genentech withdraws from the collaboration, Roche has an option to assume its place. Either Novartis or Genentech may withdraw from the collaboration on short notice, in which case rights to omalizumab revert to Tanox and the remaining collaborator unless Roche exercises its option in the event of withdrawal by Genentech. PATENTS: Protein Design Labs holds fundamental antibody humanisation patents. Protein Design Labs stated in its Annual Report for 2000 that Genentech may elect to take a patent licence for Xolair under a 1998 patent rights agreement.

CLINICAL TRIALS: Phase III clinical trials of omalizumab for the treatment of allergic rhinitis and allergic asthma were in progress with Genentech (Roche) in the USA, Canada, Europe and Japan, and are now completed. In New Zealand, the antibody was investigated in clinical trials for the treatment of allergic asthma at the Wellington School of Medicine. In the phase III trials, omalizumab was administered as a subcutaneous injection. It may also be administered intravenously. In additional phase I and II studies, the safety and efficacy of aerosol administration for allergic asthma was tested. Initial results of these studies indicated that aerosol administration is less effective than intravenous or subcutaneous administration. TEMPORARY SUSPENSION OF TRIALS: In September 2000, the US FDA requested that Genentech and Novartis suspend new trials of omalizumab. Existing long-term trials, however, could continue. The hold on new trials was due to concerns about the preclinical toxicity of omalizumab and the follow-up antibody E26. Thrombocytopenia was reported in studies in monkeys for omalizumab at 5-27 times the maximum clinical dose and for E26 at 3-15 times the maximum dose. In response to FDA requests, Novartis and Genentech carried out additional preclinical trials so that a specific explanation of the toxicity could be obtained; Novartis suspected a species specificity for the adverse events, as no thrombocytopenic events occurred in the completed phase III clinical trials. The supplementary data were submitted to the FDA and the hold on clinical trials was lifted in November 2000. REGULATORY FILINGS: in June 2000, Genentech, Novartis and Tanox submitted a Biologics Licence Application (BLA) to the US FDA for approval of omalizumab for the treatment of allergic asthma and allergic rhinitis. Novartis fileiled for marketing approval of omalizumab in the European Union, Switzerland, Australia and New Zealand. INDICATION NARROWED TO ADULT ALLERGIC ASTHMA: In July 2001, the FDA requested additional data, both preclinical and clinical, for Xolair, as well as more detailed information concerning the effect of prolonged action of the drug. Genentech is to satisfy the FDA's request with data from the ALTO platelet monitoring safety study and with ongoing open-label studies. Genentech, Novartis and Tanox believe that substantial information can be provided from continuing trials, but additional trials on specific subgroups may be necessary. The new data will be submitted to both the US FDA and the EMEA in the European Union. The application for approval of Xolair that was submitted to the EMEA was withdrawn when it became clear that there would be a delay in approval in the USA. Tanox had originally anticipated that Xolair would be launched in mid-2001 in the USA and Europe. In November 2001, Genentech and Novartis stated that an amended BLA would be submitted to the FDA in the fourth quarter of 2002. The amended approval application will focus on the use of Xolair in adults only with allergic asthma. The original application was for treatment of both adults and children, and included allergic rhinitis. Genentech has stated that it will first pursue the narrower indication before filing supplemental BLAs. Approval of the drug in the USA may now be delayed until as late as the end of 2003. In Europe, Novartis is planning to develop Xolair for use only in asthmatic patients who are classed as being 'at risk', i.e. those who have been hospitalised or have visited an emergency department. Clinical studies are to be carried out, with submission for regulatory approval planned for 2003. APPROVAL IN AUSTRALIA: In June 2002, Xolair was approved by the Therapeutic Goods Administration in Australia for the treatment of adults and adolescents with moderate allergic asthma. This is the first marketing approval for Xolair.