Roche stalls second generation fusion inhibitor, citing formulation problems

Keith Alcorn
Published: 06 January 2004

Roche today announced that a successor to its fusion inhibitor T-20 (Fuzeon) may be much further off than expected, following the discovery that the current formulation of the experimental fusion inhibitor T-1249 will not be suitable for large scale trials. Roche launched T-20, the first drug to inhibit fusion of HIV with the immune system's CD4 cells, in early 2003.

"It’s become clear that the formulation we have been using in clinical trials does not meet the technical profile that we feel confident is

reproducible for large scale production," Neil Buss, Roche’s International Medical Manager for HIV, told aidsmap today.

"We’ve been working on this problem for some time now and it’s become clear that we need to go back a stage and look at a new formulation. We aren’t abandoning T-1249 but we are stopping current clinical trials."

The setback is likely to delay a successor to Fuzeon by years rather than months, said Buss, and the company will be investigating whether molecules further back in the drug discovery process might prove a better bet than T-1249.

"We will be looking at technologies that can extend the half-life of peptide fusion inhibitors, not only T-1249 but also Fuzeon and new molecules still in development," he added.

Roche had hoped that T-1249 would be useful for patients who developed resistance to T-20 and as a more convenient injectable fusion inhibitor, and a study reported earlier this year showed that after ten days, individuals who had experienced viral load rebound on T-20 had sustained viral load reductions when treated only with T-1249.

The nearest drug candidate that might offer a salvage option for patients who experience failure of T-20 will now be Pfizer's chemokine antagonist UK-427,857 (click here for further details), which is unlikely to be available through expanded access before 2006. Today's announcement is likely to make clinicians more wary about prescribing Fuzeon without the support of other new agents such as tipranavir, since research shows that T-20 is least effective when it is the only agent in a new regimen to which in individual's virus is susceptible.

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Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

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