More threat to Gilead's HIV business? GlaxoSmithKline touts long-acting injectable PrEP win against Truvada

Just as GlaxoSmithKline launches an assault at Gilead Sciences’ HIV business in the treatment realm, it’s also targeting the prevention market with new data backing a more convenient alternative to existing offerings.

Gilead’s Truvada won the first FDA nod in 2012 to reduce the risk of HIV infection as a PrEP regimen. Now, GSK has shown its long-acting injectable cabotegravir, given every two months, worked just as well at fending off the virus as Gilead’s daily pill.

Interim analysis of a large-scale global clinical trial involving 4,600 participants found cabotegravir is 69% more effective than Truvada at preventing HIV infection in men and transgender women who have sex with men, GSK said Monday.

Twelve people (0.38%) in the cabotegravir arm contracted HIV, while 38 (1.21%) treated with Truvada got the virus. Statistically speaking, the 69% advantage shown by cabotegravir didn’t clear the bar for GSK to tout it as superior to Gilead's drug. But experts on an independent data monitoring panel recommended the study be stopped early on strong efficacy, and that Truvada patients be offered cabotegravir.

“These study results demonstrate that long-acting injectable cabotegravir dosed every two months can successfully reduce HIV acquisition in at-risk MSM and transgender women,” Kimberly Smith, head of R&D at GSK’s ViiV Healthcare unit, said in a statement.

Data are not yet available as to how those trial participants got infected, whether through noncompliance or drug resistance. GSK said it will present detailed results at an upcoming scientific meeting and will use the data to seek regulatory approvals.

RELATED: Gilead's Descovy not worth the higher price over forthcoming Truvada generics: study

Meanwhile, Gilead’s been busy converting Truvada takers to Descovy—a newer regimen with a better bone and kidney safety profile than its predecessor—before it loses patent protection in September. That effort’s been progressing well.

About 38% of U.S. PrEP users are now taking Descovy, CEO Daniel O’Day said during a conference call in late April. Despite slower switchovers and fewer new initiations during COVID-19, chief commercial officer Johanna Mercier said the company is still confident in its goal of transferring 40% to 45% of the PrEP business to the new drug by the end of the year.

Besides a clear trend toward better efficacy, GSK’s key argument for injectable cabotegravir is its ability to cut the frequency of dosing from daily to six times a year. That could translate into better adherence and hence improved protection.

The British pharma is currently using cabotegravir in tandem with Johnson & Johnson’s rilpivirine in a long-acting regimen for treating HIV patients. The once-monthly version of that therapy, called Cabenuva, recently won a Canadian nod, though it previously suffered a rebuff from the FDA due to manufacturing problems. ViiV recently rolled out data showing the combo, given every two months, was similarly effective at suppressing HIV as monthly Cabenuva after 48 weeks of treatment.

RELATED: GSK's ViiV touts 2-month HIV data as sister injection Cabenuva awaits FDA redemption

The current study, dubbed HPTN 083, was conducted by the NIH under its HIV Prevention Trials Network, a collaboration that’s testing many HIV preventative methods. A sister trial, HPTN 084, is pitting cabotegravir against Truvada in African women who are at risk of HIV infection.

The dosing frequency advantage of cabotegravir could be more important in women, too. Previous studies have suggested that women need to be more adherent to PrEP than men for the prophylactic measure to work.

But women represent a much smaller PrEP population, making up about 10% of all PrEP takers, according to Gilead. Descovy is currently not approved for cisgender women.

Editor's Note: The story has been updated with the correct number of infections in the Truvada arm in the HPTN 083 study.