Tanox studies show drug candidate TNX-355 inhibits entry of HIV-1 into healthy CD4-positive cells

By E. Janene Geiss

Philadelphia, Dec. 19 - Tanox, Inc. said Monday that data on its lead HIV drug candidate, TNX-355, shows the compound's unique ability to inhibit entry of HIV-1 into healthy CD4-positive cells regardless of the virus' co-receptor tropism.

TNX-355 is a humanized viral-entry inhibitor monoclonal antibody that coats CD4-positive cells - the primary target of HIV infection. By blocking viral entry into the CD4 cell in this manner, TNX-355 creates a unique new hurdle for HIV, different from entry inhibitors that target viral proteins or chemokine co-receptors, according to a company news release.

Study results show that TNX-355 is equally active in vitro against virus strains that exhibit tropism for CCR5 as well as CXCR4, making TNX-355 the most advanced entry inhibitor in development with this crucial property of tropism independence, officials said.

"TNX-355 shows significant antiviral activity and could be a powerful new advancement in the treatment of HIV," Stanley Lewis, Tanox medical director, said in the release.

"These new data confirm that unlike other viral-entry inhibitors that target cellular proteins, TNX-355 is equally effective against viruses regardless of tropism. This is extremely important, as a significant proportion of treatment-experienced patients harbor mixed virus or dual-tropic virus," Lewis added.

Results of this research were presented at the American Society for Microbiology's Interscience Conference on Antimicrobial Agents and Chemotherapy annual meeting in Washington, D.C.

Other research presented at the conference included results from a study testing TNX-355 with another entry inhibitor, enfuvirtide, which showed synergy between the two agents was demonstrated by conventional in vitro techniques, officials said.

These data support the use of TNX-355 and enfuvirtide together in the clinical setting, officials said.

Because HIV must be treated with combination therapy, negative drug-drug interactions are a major concern for clinicians treating the disease. These results suggest that co-administration of TNX-355 and enfuvirtide may enhance the activity of both agents, officials said.

And, as previously announced by the company in October, results in the 24th week of a phase 2 clinical trial demonstrated that when compared with an optimized background regimen alone, TNX-355 in combination with an optimized background regimen reduces viral loads in HIV-infected patients without suppressing their immune systems or causing significant side effects.

The company said Monday that it 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 Food and Drug Administration in early 2006 to determine next steps for development, officials said.

Tanox is a Houston biotechnology company specializing in the discovery and development of monoclonal antibodies.

© 2015 Prospect News.
All content on this website is protected by copyright law in the U.S. and elsewhere. For the use of the person downloading only.
Redistribution and copying are prohibited by law without written permission in advance from Prospect News.
Redistribution or copying includes e-mailing, printing multiple copies or any other form of reproduction.