Etravirine

Abstract

Etravirine [TMC 125] is a next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) that is being developed by Tibotec (Tibotec-Virco Group; now Johnson & Johnson) for the treatment of HIV-1 infections. Etravirine is a highly flexible, di-aryl-pyrimidine (DAPY) compound. The flexibility enables favourable binding interactions with mutant HIV strains as well as wild-type virus. Etravirine has superseded dapivirine as Tibotec's lead NNRTI in clinical development worldwide. Tibotec merged with Virco to form Tibotec-Virco Group in March 2001. Subsequently, Tibotec-Virco Group was acquired by Johnson & Johnson on 18 April 2002. Etravirine was discovered by Tibotec in collaboration with the Janssen Research Foundation. However, the Janssen Research Foundation is no longer involved in the development of etravirine. Etravirine has received fast-track status from the US FDA for the treatment of HIV-1 infections. An expanded access programme for etravirine began in the US in September 2006. The programme made etravirine available to HIV-1 infected adults who have limited treatment options due to virological failure or intolerance to multiple antiretroviral regimens. The progamme will also be introduced in Canada and Europe. In November 2005, Tibotec initiated two randomised, placebo-controlled phase III trials of etravirine in treatment-experienced HIV-1 infected patients with NNRTI resistance and at least three primary protease mutations. The two trials will each enroll 600 patients and will be conducted in 18 countries. Darunavir will be used as the background protease inhibitor in the trials. This is the first time that two investigational antivirals have been evaluated in combination in heavily treatment-experienced patients. The trial design is supported by the FDA, the Committee for Medicinal Products for Human Use (CHMP) of the EMEA and the HIV patient community. Patient enrolment in the two phase III trials was completed in September 2006. A multicentre phase IIb dose-finding study (TMC125 C223) in Europe, Canada and the US found etravirine significantly reduced the HIV viral load in a subset of heavily treatment-experienced patients. Tibotec discontinued a single exploratory open-label phase II trial (TMC 125-C227) of etravirine in November 2005. The discontinuation was a result of 12-week data, which demonstrated a difference in the proportion of patients achieving or maintaining undetectable viral load in favour of the control group, who were receiving protease inhibitor-based treatment. There were no safety concerns and the discontinuation had no effect on phase III registration trials. Phase IIa clinical trials of etravirine for the treatment of HIV infections, initiated in November 2001, have been completed. Tibotec has conducted a phase I trial (TMC125-C157 study) evaluating etravirine + didanosine among healthy volunteers in Belgium; trial results have been presented.