The pending introduction of a new formulation of tenofovir, a prodrug of the original formulation, raises the question of equivalence in terms of outcomes and virological suppression and adverse effects. Don Smith and Mark Bloch presented data clearly showing that the newer formulation of tenofovir - tenofovir alafenamide (TAF) is superior to the original tenofovir disoproxil fumarate (TDF). TDF, while a very effective agent, may cause clinical renal toxicity and adversely affect bone marrow density. TAF is a novel prodrug that has a 90% reduction in serum plasma tenofovir levels and hence has the potential to reduce the adverse effects seen with TDF.
The speakers presented results of the GS-292-0109 study which looked at tenofovir disoproxil fumarate (TDF) 300mg switch to tenofovir alafenamide (TAF) 10mg in a cohort of well controlled patients at 48 weeks on once daily optimised background therapy. 1196 patients were randomised 2:1 to receive TAF based therapy to TDF based therapy with virological success occurring at least equally across both groups indicating non- inferiority. Further positive results were seen in the TAF group where Statistically significant increases in BMD and multiple tests of renal function compared to those patients on theor prior TDF based regimen. Lipid profiles however favoured TDF based regimens. These results support the preferential use of TAF, especially in those at risk of metabolic and/or renal adverse effects.......well when it becomes available!