No Resistance With Vertex' HIV Therapy?

Vertex Pharmaceuticals has reported interim data from a four-week PhaseI/II clinical study with the HIV protease inhibitor VX-478 which shows that resistance to the drug did not develop when administered as a monotherapy. Results were presented at the 4th Conference on Retroviruses and Opportunistic Infections, held in Washington DC, USA, on January 24.

42 patients were enrolled in the dose-escalating study which found a correlation between inhibitor plasma trough levels and the reduction in viral load. After four weeks of treating patients with the drug as a single-agent therapy, no mutations were noted in the amino acids of the HIV protease enzyme which binds the drug to the site of action. In addition, says the company, "researchers did not observe any of the mutations previously identified in laboratory experiments designed to generate virus resistance to VX-478."

However, Joshua Boger, president and chief executive of Vertex, issued a warning that the results should be "interpreted with caution," due to the length of the trial. Although the data looks very promising there is no knowledge as yet concerning the development of resistance over an extended period of time, or in combination with other antiretrovirals, he said.