Gilead challenges ViiV in resistant HIV, filing twice-yearly therapy

Gilead Sciences has filed for FDA approval of a long-acting therapy for resistant HIV infections that only needs to be administered once every six months.

The marketing application for capsid inhibitor lenacapavir throws down a gauntlet to arch rival ViiV Healthcare, which secured FDA approval for its multidrug resistant HIV therapy Rukobia (fostemsavir) last year.

Lenacapavir (previously GS-6207) is the first in a new class of HIV drug that Gilead is hoping will eventually free patients from the need to take daily oral tablets, although initially it is being filed for patients who are failing their current treatment regimen because of viral resistance.

The filing is based on data from the phase 2/3 CAPELLA trial of lenacapavir administered subcutaneously every six months in combination with an oral antiretroviral therapy (ART) regimen to people with multidrug resistant (MDR) HIV.

The 36-patient CAPELLA trial tested lenacapavir in highly treatment-experienced HIV patients who had developed resistant to their current drugs, with virus levels rising as a result. It found that 21 of 24 (88%) of patients on the capsid inhibitor experienced a 0.5 log10 reduction in viral load after 14 days, compared to two of 12 patients (17%) on placebo.

The FDA granted breakthrough designation to lenacapavir for the treatment of resistant HIV, which has become a niche part of the overall HIV market thanks to much-improved oral drug regimens in recent years.

Gilead has ambition to extend the use of lenacapavir into additional and much larger indications, including the general HIV-positive population as well as for pre-exposure prophylaxis (PrEP) among people who have sex with HIV-positive partners.

That's another potential challenge to ViiV – majority owned by GlaxoSmithKline – which has placed the development of longer-acting HIV therapies that reduce the burden of dosing and improve compliance at the heart of its new drug development strategy.

ViiV already sells a long-acting HIV treatment – Cabenuva (cabotegravir/rilpivirine) – which is partnered with Johnson & Johnson and requires a monthly injection rather than daily tablets. It has also just signed a partnership with Halozyme to develop a new clutch of long-acting HIV therapies.

The $740 million deal with Halozyme is focused on extending dosing intervals to three or six months – or potentially even longer – for four ViiV HIV drugs.