WASHINGTON, Dec. 17 /PRNewswire-FirstCall/ -- Tanox, Inc. today presented further analysis of a Phase 2 study of its novel HIV antibody, TNX-355, in a late-breaking submission at the American Society for Microbiology’s Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC). The company, which recently released favorable Week 24 viral-reduction results for the drug candidate, had an abstract at the meeting. The presentation provided details on several endpoints of the study.
In addition to meeting the primary endpoint of mean change in viral load from baseline with statistical significance, TNX-355, combined with an optimized background regimen (OBR), demonstrated considerable virologic benefit compared to OBR alone as measured by average area under the curve minus baseline (AAUCMB). The AAUCMB for the 15 milligram-per-kilogram (mg/kg) dose arm was a 0.97 log(10) reduction (p=0.001) in viral load by Week 24, while the AAUCMB for the 10 mg/kg dose arm was a 1.20 log(10) reduction (p<0.001) in viral load. The placebo arm produced a 0.41 log(10) reduction. Food and Drug Administration (FDA) guidance on antiviral agents recognizes time-averaged measures of viral-load suppression, such as AAUCMB, as key efficacy endpoints for HIV therapies in treatment-experienced patients.
The antiviral activity of both of the TNX-355 arms also was greater than that of placebo when assessed by another important efficacy criterion - time- to-virologic failure, which measures durability of response. At the Week 24 time point, the median time-to-virologic failure had not been reached for either the 15 mg/kg or the 10 mg/kg arm. Median time-to-virologic failure was 86 days in the placebo group.
“These clinical results demonstrate that TNX-355 provides virologic benefit to a broad range of treatment-experienced patients,” said Dr. Daniel Kuritzkes, director of the AIDS Research Section of Retroviral Therapeutics at Brigham and Women’s Hospital, Harvard Medical School in Boston, Mass. “In addition, there have been no apparent drug-drug interactions, which would be a significant advantage and allow greater flexibility in combining TNX-355 with other drugs. As an antibody, TNX-355 should not have toxicities that are associated with many currently available drugs.”
Additional analyses highlighted at ICAAC included: -- Percentage of patients who achieved a viral-load reduction of at least 0.5 log(10) -- Percentage of patients who achieved a viral-load reduction of at least 1.0 log(10) -- Change in percentage and number of CD4-postive cell count from baseline
In the 15 mg/kg dose arm, 50 percent of patients (p=0.050) achieved a viral-load decrease of at least 0.5 log(10) at Week 24, and 36 percent of patients had a viral-load decrease of at least 1.0 log(10) at Week 24. In the 10 mg/kg dose arm, 56 percent of patients (p=0.024) achieved a viral-load decrease of at least 0.5 log(10) at Week 24, while 44 percent of patients had a viral-load decrease of at least 1.0 log(10) at Week 24. In the placebo group, 22 percent of patients achieved a viral-load decrease of at least 0.5 log(10) at Week 24, and 22 percent of patients had a viral-load decrease of at least 1.0 log(10) at Week 24.
Although the study was not prospectively powered to demonstrate statistical significance in measuring CD4-positive cell counts at Week 24, increases in immune-supporting CD4 cells were seen in all study arms. In the 15 mg/kg arm, mean absolute CD4 cell count increased 18 percent at Week 24 (274 cells/mm(3), compared to 223 cells/mm(3) at baseline). There was a 3 percent increase in the 10 mg/kg arm at Week 24 (308 cells/mm(3), compared to 299 cells/mm(3) at baseline), and a 1 percent increase at Week 24 in the placebo group (249 cells/mm(3), compared to 246 cells/mm(3) at baseline).
No serious adverse events that were considered related to TNX-355 were reported through Week 24 and there were no infusion-site reactions to the intravenous mode of administration.
These analyses underscore the potential of TNX-355 as a treatment in the fight against HIV. The company will continue the Phase 2 trial through its planned 48-week duration, and administration of TNX-355 has been extended up to 96 weeks for patients who continue to receive benefit from the drug candidate. Tanox is planning to confer with the FDA in early 2006 to determine next steps for development.
“As we continue to analyze the data we’ve culled so far, we’re seeing viral-load reduction results comparable to those seen with approved HIV therapies,” said Dr. Stanley Lewis, Tanox medical director. “This is encouraging for us as a company, for viral-entry inhibitors as a therapeutic class, and for treatment-experienced patients who may one day benefit from our work.”
About TNX-355
TNX-355 is a humanized monoclonal antibody that binds to CD4 receptors on the surface of CD4-positive cells, preventing the entry of HIV particles into lymphocytes. Phase 1 studies demonstrated that TNX-355 is active against multiple strains of HIV and does not deplete CD4 cells. The 48-week Phase 2 study, which met its Week 24 primary endpoint, is a double-blind trial to compare the safety and efficacy of two dosages of TNX-355, each combined with an optimized background regimen (OBR), to OBR therapy alone among HIV-1 treatment-experienced patients. The drug was fast tracked by the Food and Drug Administration in 2003. The fast-track designation expedites approval of therapies for life-threatening diseases and allows for rolling new drug application (NDA) submissions.
About Tanox, Inc.
Tanox is a biotechnology company specializing in the discovery and development of monoclonal antibodies. The company develops innovative biotherapeutics for the treatment of immune-mediated diseases, inflammation, infectious disease and cancer. Tanox’s lead investigational therapy, TNX-355, is viral-entry inhibitor antibody to treat HIV/AIDS. TNX-355 has shown significant antiviral activity in Phase 2 clinical testing. 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 absence of safety concerns after 24 weeks of treatment in 82 patients does not ensure that safety issues will not be identified after extended treatment or in larger-scale clinical trials. The therapeutic potential of TNX-355 as a treatment for HIV-1-infected patients is subject to the risks inherent in drug development. 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.
Photo: NewsCom: http://www.newscom.com/cgi-bin/prnh/20050207/TNOXLOGOPRN Photo Desk, photodesk@prnewswire.comTanox, Inc.
CONTACT: Steve Sievert of Tanox, Inc., +1-713-578-4211, ssievert@tanox.com
Web site: http://www.tanox.com//
