TNOX Tanox (MM)

Novel viral-entry inhibitor antibody shown to be well-tolerated TORONTO, Aug. 17 /PRNewswire-FirstCall/ -- New data presented today by Tanox, Inc. (NASDAQ:TNOX) confirm that TNX-355, when used in combination with an optimized background regimen (OBR) of antiretroviral drugs, produced a sustained virologic response in treatment-experienced HIV patients through 48 weeks. The findings are part of an analysis of 48-week data from a Phase 2 clinical trial of TNX-355 presented at the 2006 International AIDS Conference in Toronto. Data presented at the conference included several 48-week secondary endpoints of the study, including percentage of patients who achieved a viral- load reduction of at least 0.5 log10 and at least 1.0 log10, median time-to- loss of virologic response and change in number of CD4+ cells. As previously reported, the study met its primary endpoint of mean viral-load reduction from baseline at Week 24. In the 10 mg/kg dose arm of TNX-355 plus OBR, 44 percent of patients had a viral-load reduction of at least 0.5 log10 at 48 weeks (p=0.014), while 39 percent of patients in the 15 mg/kg dose arm achieved at least a 0.5 log10 decrease in viral load (p=0.029). In the placebo arm, 11 percent of patients achieved a decrease of at least 0.5 log10. A 0.5 log10 reduction in viral load is considered to have clinical benefit for patients. Although the 82-patient trial was not designed to demonstrate statistical significance with a 1.0 log10 viral-load reduction at 48 weeks, a clear trend was observed. In the 10 mg/kg dose arm, 37 percent of patients had a viral- load reduction of at least 1.0 log10, while 32 percent of patients in the 15 mg/kg dose arm achieved at least a 1.0 log10 reduction. In the placebo group, 11 percent of patients had at least a 1.0 log10 viral-load reduction. A 1.0 log10 reduction in viral load is equivalent to a 90 percent decrease of HIV in the bloodstream. Additionally, the durability of the antiviral activity of the TNX-355 regimens plus OBR at 48 weeks was greater than that of placebo plus OBR when assessed by another secondary endpoint -- median time-to-loss of virologic response. At Week 48, the median time-to-loss of virologic response was 230 days in the 10 mg/kg dose arm and 253 days in the 15 mg/kg dose arm. Both of these results were statistically significant (p=0.003). Median time-to-loss of virologic response was zero days in the placebo group. "These results show that TNX-355-based regimens were able to suppress viral loads for nearly one year in a considerable number of treatment- experienced patients in the study," said Dr. Stanley Lewis, Tanox medical director for TNX-355. "The durable response demonstrated by TNX-355 plus OBR, compared to OBR alone in this patient population, indicates that TNX-355 could be a valuable therapy for patients who are faced with limited treatment options." Impact on CD4+ Cells and Safety As previously reported, patients on the TNX-355 regimens had greater CD4+ immune cell count increases at 48 weeks than patients in the placebo arm. Patients in the 10 mg/kg dose arm had a mean CD4+ cell increase of 48 cells/mm3 (p=0.031), while patients in the 15 mg/kg dose arm experienced a mean CD4+ cell increase of 51 cells/mm3 (p=0.016). Patients in the placebo arm had a mean increase of 1 CD4+ cell/mm3. The number of adverse events reported for the TNX-355 regimen arms was not statistically different from the number reported for the placebo group. No severe adverse events considered related to TNX-355 were reported through 48 weeks and there were no reported infusion-site reactions associated with the intravenous administration. TNX-355 did not appear to add toxicities to the background regimens and discontinuation rates related to adverse events were comparable between the treatment arms and the placebo arm. In addition to the Phase 2 study oral abstract presented today at the conference, Tanox presented an abstract highlighting in vitro findings of TNX- 355's activity against enfuvirtide-resistant HIV. The abstracts and slides from the oral presentation are available on the Tanox Web site (http://www.tanox.com/). TNX-355 Phase 2 Study Design The Phase 2 study, which is continuing to 144 weeks, is a double-blind trial to compare the safety and efficacy of two dosages of TNX-355, each combined with OBR, to OBR therapy alone in HIV-1 treatment-experienced patients. Patients were randomized 1:1:1 to receive 10 mg/kg, 15 mg/kg or placebo every two weeks. Patients in the 10 mg/kg dose arm also received a loading dose of 10 mg/kg every week for eight weeks. About TNX-355 TNX-355 is the most-advanced humanized monoclonal antibody in development to treat HIV/AIDS. TNX-355 is distinct from other entry inhibitors in that it binds to CD4 receptors -- the primary target of HIV infection. The drug candidate has a Fast Track designation from the FDA. The company is currently in discussions with the FDA regarding clinical-trial design options for the next stage of TNX-355 development. About Tanox, Inc. Tanox is a biotechnology company specializing in the development of monoclonal antibodies. The company develops innovative biotherapeutics for the treatment of immune-mediated diseases, inflammation, infectious disease and cancer. Tanox's first-approved drug, Xolair(R) (omalizumab), is the first antibody approved to treat moderate-to-severe confirmed allergic asthma. Xolair was developed in collaboration with Genentech, Inc. and Novartis Pharma AG and is approved for marketing in the United States, Canada and major European countries. Tanox is based in Houston and has a manufacturing facility in San Diego. Additional corporate information is available at http://www.tanox.com/. This news release contains forward-looking statements regarding the potential for TNX-355 as a treatment for HIV-1-infected patients. These statements are based on Tanox's current beliefs and expectations, and are subject to risks and uncertainties that could cause actual results to differ materially. The therapeutic potential of TNX-355 as a treatment for HIV-1- infected patients is subject to the risks inherent in drug development. The conduct or timing of any future trials can depend on many factors, including the company's discussions with the FDA, whether Tanox chooses to partner the program, and availability of sufficient quantities of clinical-trial material. Success in early stage clinical trials does not ensure that later-stage or larger-scale clinical trials will be successful, and the results achieved in later-stage trials may not be sufficient to meet applicable regulatory standards. Problems or delays may arise during clinical trials or in the course of developing, testing or manufacturing drugs. For more detailed information on the risks and uncertainties associated with Tanox's drug development and other activities, see Tanox's periodic reports filed with the Securities and Exchange Commission. The Tanox logo is a registered trademark with the U.S. Patent and Trademark Office. http://www.newscom.com/cgi-bin/prnh/20050207/TNOXLOGO DATASOURCE: Tanox, Inc. CONTACT: Steve Sievert of Tanox, Inc., +1-713-578-4211, Web site: http://www.tanox.com/

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