Gilead Sciences today announced that it has decided to abandon its research programme to develop the experimental nucleoside analogue amdoxovir (DAPD). Rights to develop the drug will pass back to Emory University and the University of Georgia Research Foundation.
Gilead says that it is halting its amdoxovir research programme because it thinks that other drugs in the company's development pipeline hold more promise. Gilead announced earlier this month that it is developing a new protease inhibitor code-named GS9005. The company is also developing a new formulation of its highly successful nucleotide analogue tenofovir (code named GS 7340), using a lipid-based technology that will deliver the drug more effectively to the lymphatic system (the main reservoir of HIV in the body). Gilead’s new protease inhibitor will be developed using the same technology.
Data presented at the 2003 Conference on Retroviruses and Opportunistic Infections showed that five out of 18 patients who received the drug in a phase I/II study in amdoxovir developed `lens opacities` within 12 weeks. An animal study in monkeys has also demonstrated that amdoxovir might affect vision: at high doses the drug caused glucose elevations and cataracts (lens opacity is defined as the development of opaque patches on the periphery of the field of vision, whilst cataracts are more serious obstructions of the field of vision).
Two clinical trials of amdoxovir, ACTG 5118 (T-20 plus amdoxovir or placebo plus optimised background) and ACTG 5165 (amdoxovir plus mycophenolate or placebo), will continue, but the product’s development path must now be uncertain. Amdoxovir is the second drug this month to be halted in clinical development; earlier this month Roche and Trimeris announced that their second-generation fusion inhibitor T-1249 was being being pulled from clinical studies owing to formulation problems.