GlaxoSmithKline PLC said on Feb 6 it has signed a deal with U.S. biotech company Idenix Pharmaceuticals Inc. to develop IDX899, its HIV drug in development. IDX89, a once daily, oral treatment, belongs to a class of drugs called non-nucleoside reverse transcriptase inhibitors (NNRTI), that block the enzyme HIV needs to multiply. Glaxo will take over the development and associated costs for IDX899, and Idenix will receive in return a payment of $34 million at once and $416 million after reaching regulatory approval and sales targets.