Roche has been forced to suspend development of one of its new HIV drugs because of formulation problems. The Swiss pharmaceutical company was developing the drug, an HIV fusion inhibitor called T-1249, in conjunction with Trimeris, a US biotechnology company. On a more positive note, however, Roche recently announced that it has signed a further research agreement with Trimeris to discover, develop and commercialise the next generation of HIV fusion inhibitors.

Roche and Trimeris established their first research collaboration in 1999. This led to the development of Fuzeon (enfuvirtide), the world's first commercialised HIV fusion inhibitor, which obtained US and EU regulatory approval last year.

Fusion inhibitors represent a new class of peptide-based HIV drug that prevents the virus from entering CD4 immune cells; all other HIV drugs, such as protease inhibitors, attack HIV after it has entered the cell. Fuzeon is therefore used in conjunction with other HIV drugs, and can reduce the amount of the virus in the blood and increase numbers of CD4 cells.

Under the terms of the new agreement, Roche and Trimeris will develop improved formulation and delivery technologies to allow less frequent administration of HIV fusion inhibitors and look to discover new peptides with enhanced efficacy and resistance profiles for use as fusion inhibitors.

Despite the success of Fuzeon, the difficulties of developing new fusion inhibitors are demonstrated by the suspension of work on T-1249, which Roche and Trimeris blamed on 'challenges with achieving the technical profile of the current formulation'. The companies hope that their research into new formulations and delivery technologies may help to re-start the T-1249 programme. 

JE