Gilead Sciences has completed two phase III trials of a new, better-tolerated four-drug HIV regimen that should be filed for approval in the US and EU before the end of the year.
The new fixed-dose, single-tablet formulation is based on the same cocktail of drugs used in Gilead’s big-selling HIV drug Stribild, which will likely clear $1bn in sales this year, but uses a variant of one of the active ingredients that is less likely to cause side effects such as impaired kidney function.
Like its predecessor Stribild, the new drug contains cobicistat, emtricitabine and elvitegravir but replaces tenofovir disoproxil with a prodrug called tenofovir alafenamide fumarate (TAF), which is only activated in the body when metabolised.
Stribild’s four-in-one combination gives HIV patients a simpler treatment option
The two phase III trials show that the TAF-based regimen was at least as effective as Stribild based on the number of patients taking it who had HIV viral load of less than 50 copies per millilitre of blood after 48 weeks’ therapy, but demonstrated “more favourable renal and bone safety,” according to Gilead.
Both trials involved HIV patients who had not been treated with antiretroviral therapy before and compared the two drug regimens for efficacy as well as safety measures such as the change in bone mineral density (BMD) from baseline and kidney function tests, including glomerular filtration rate (GFR), which gives an indication of how efficiently the kidneys are working.
Treatment discontinuation rates and laboratory abnormalities tended to be similar between the groups, but TAF-treated patients experienced significantly smaller reductions in estimated (GFR) and BMD at the hip and lumbar spine than Stribild-treated subjects.
Commenting on the results, Gilead’s chief scientific officer Norbert Bischofberger said: “as individuals with HIV are living longer, there is a need for treatments that are not only highly effective, but also offer an improved safety profile.”
“We believe that the [TAF] single tablet regimen has the potential to optimise HIV therapy for a wide range of treatment-naïve patients,” he added.
While a lot of attention is being paid to Gilead’s burgeoning hepatitis C franchise headed by mega-blockbuster Sovaldi (sofosbuvir), as well as its emerging cancer pipeline, the latest data indicates that the company’s core HIV portfolio is continuing to deliver the goods.
Analysts at RBC Capital Markets said the data on TAF was better than expected – adding that expectations were already pretty high – and should help drive growth for Gilead’s HIV franchise beyond 2018.
TAF could also give Gilead a sizeable extension on the patent life for tenofovir, given that protection for the tenofovir disoproxil fumarate salt expires in 2017-2018 in the US.