ViiV Healthcare has unveiled late-stage data showing that an experimental two-drug regimen of its dolutegravir and Janssen Science's rilpivirine was comparable in efficacy to three- or four-drug antiretroviral regimens in virologically suppressed patients.

The dolutegravir/rilpivirine regimen achieved non-inferior viral suppression at 48 weeks compared with a three- or four-drug regimen in both pooled and individual analyses of the Phase III SWORD 1 and SWORD 2 studies, the firm noted, with virologic suppression rates were similar between treatment arms.

On the safety side, the most commonly reported (>5 percent) adverse events in the dolutegravir and rilpivirine arm were nasopharyngitis, headache, diarrhoea and upper respiratory tract infection, while those in the conventional antiretroviral therapy (CAR) arm were nasopharyngitis, upper respiratory tract infection, back pain, headache and diarrhoea.

The overall rate of serious adverse events was comparable between treatment groups (dolutegravir/rilpivirine: 27, CAR: 21). A greater number of adverse events were reported and led to withdrawal from the study in the two drug regimen arm compared to the CAR group (dolutegravir/rilpivirine: 21, CAR: 3), but ViiV noted that this is to be expected given that patient were being switched from a stable regimen to a new one.

John C Pottage, chief scientific and medical officer of ViiV Healthcare, said the results "may change our understanding of how HIV can be managed".

"For more than 20 years we thought that three or more drugs were required to maintain virologic suppression, but the SWORD studies provide compelling data that suppression may be maintained with a two drug regimen of dolutegravir and rilpivirine. These data mark an exciting first step towards making two drug regimens a reality in HIV treatment," he noted.

ViiV, which is majority-owned by GSK, with Pfizer and Shionogi as shareholders, said it is planning on filing the two-drug regimen for HIV-1 maintenance therapy with regulatory authorities sometime this year.