DESCRIPTION: TNX-355 is an experimental entry inhibitor being developed by Tanox and Biogen Idec. TNX-355 contains synthetic (man-made) antibodies, known as monoclonal antibodies. These antibodies bind to the CD4 receptor on T-cells. Once TNX-355 binds to these receptors, HIV cannot successfully connect with the surface of T-cells, thus preventing the virus from infecting healthy cells.
A phase II clinical trial has been completed. It enrolled 82 HIV positive people who had tried and failed other anti-HIV drugs in the past. All of the patients enrolled in the study received optimized background treatment (any combination of approved anti-HIV drugs), based on the results of drug-resistance testing. Two-thirds of the patients also received one of two doses of TNX-355 (10mg or 15mg per kilogram of body weight); the remaining one-third of the patients received placebo. The drug (or placebo) was administered through an IV line once a week for the first nine weeks and then once every other week for the remainder of the study.
FINDINGS: After 48 weeks, treatment with the 10mg/kg dose of TNX-355 resulted in a viral load reduction of 0.96 log; treatment with the 15mg/kg dose resulted in a viral load reduction of 0.71 log. In the placebo group, there was a viral load reduction of 0.14 log. Patients in both TNX-355 treatment groups experienced greater CD4 cell increases compared to those in the placebo group (an average increase of 48 T-cells in the 10 mg/kg group, an average increase of 51 CD4 cells in the 15 mg group, and an average increase of 1 CD4 cell in the placebo group). Both doses of TNX-355 were well tolerated.
