People living with HIV could swap daily doses of tablets with a monthly or bi-monthly injection, if a new clinical trial meets its objectives.
An HIV regimen combining Johnson & Johnson subsidiary Janssen's rilpivirine with ViiV Healthcare's cabotegravir will start clinical testing shortly and - if it proves effective - could be an alternative to current triple-drug therapy for the infection after an initial regimen of virus suppressing drugs.
ViiV - a joint venture between GlaxoSmithKline, Pfizer and Shionogi - said that while HIV can be considered a manageable condition with access to modern drugs, there are still a number of areas for improvement including "tolerability, safety, dosing schedules, drug interactions and adherence".
Cabotegravir is a long-acting, investigational integrase inhibitor, while rilpivirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that is already sold by Janssen under the Edurant brand name. The latter also features in combination HIV therapy Complera/Eviplera (rilpivirine, emtricitabine and tenofovir), which Janssen sells with partner Gilead Sciences.
Towards the end of last year ViiV and Janssen reported results from the phase IIb LATTE 2 trial, in which people with HIV were initially treated with oral therapy and then either kept on oral or doses with cabotegravir/rilpivirine every four or eight weeks.
Over the course of the 32-week trial, both injection frequencies matched the oral regimen in the suppression of HIV, with a low rate if withdrawal from therapy despite some injection site reactions, providing proof of principle for the concept.
The phase III programme for the combination will look at the potential for patients on oral regimens to switch to cabotegravir/rilpivirine without loss of antiviral cover.
At its recent R&D day, ViiV majority shareholder GSK said it is anticipating a launch for the new drug as an HIV treatment in 2019 or 2020, and sees it as a key new product as it jostles for market share in the HIV market alongside arch-rival Gilead.
The company is also developing cabotegravir as a monotherapy for the prevention of HIV infection in at-risk populations, and recently announced a collaboration with the National Institutes of Health in the US to combine the drug with neutralising antibody candidate.
The combination's long-half life in the body means it raises the possibility of "better adherence, potentially turning into a resistance advantage because you don't miss doses, and potentially … the possibility of improved quality of life" for some HIV patients, commented GSK's head of pharma R&D Patrick Valance.