Gilead, MSD share data on once-weekly oral HIV treatment

Gilead Sciences and MSD's once-weekly oral medicine for HIV has been shown to achieve high rates of viral load suppression in two phase 3 trials, setting up regulatory filings for what could be the first drug of this type if approved.

The combination of capsid inhibitor lenacapavir (LEN) and nucleoside analogue islatravir (ISL) given in a single tablet was found to be effective in the ISLEND-1 and ISLEND-2 trials, which involved people living with HIV who switched to the once-weekly pill from stable treatment with daily oral antiretroviral therapy (ART).

In both studies, ISL/LEN was non-inferior to the comparator drug – Gilead's Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide) in the case of ISLEND-1 and a range of other daily ART regimens in ISLEND-2 – at controlling HIV over 48 weeks of follow-up.

In ISLEND-1, no patients who switched to the once-weekly pill saw levels of HIV rise above 50 copies/mL, the benchmark for undetectable infection, compared to 0.3% of those who stayed on Biktarvy. In ISLEND-2, the rates were 0.3% and 1.3%, respectively.

Participants who switched to once-weekly oral ISL/LEN reported higher treatment satisfaction and lower treatment burden, according to Gilead and MSD, known as Merck & Co in the US and Canada.

Lenacapavir is already approved by the FDA as Sunlenca for use in combination with other ARTs in people living with multidrug-resistant (MDR) HIV, and as a twice-yearly injection called Yeztugo for people who need HIV pre-exposure prophylaxis (PrEP), for example because they are in a relationship with someone who is HIV-positive.

In June, Gilead also filed for approval of a once-weekly formulation of lenacapavir alone for PrEP, as an alternative to its widely used, daily oral product Descovy (emtricitabine/tenofovir alafenamide), which made global sales of $2.8 billion last year.

Some analysts have also predicted that lenacapavir could eventually become a $4.5 billion blockbuster across its various formulations.

Islatravir, meanwhile, was approved by the FDA in April under the Idvynso brand as a fixed-dose combination with non-nucleoside reverse transcriptase inhibitor (NNRTI) doravirine as a daily oral option for HIV treatment.

"Once-daily, combination, single-tablet antiretroviral therapy is the cornerstone of HIV treatment today. However, the treatment landscape is evolving," said Jürgen Rockstroh, of University Hospital Bonn in Germany, an ISLEND-1 investigator.

"Long-acting therapies provide an alternative to daily pills," he added. "The ISLEND-1 study results show the potential of ISL/LEN as the first once-weekly oral single-tablet treatment option."