ViiV Healthcare, a global specialist HIV company established in November 2009 by GSK and Pfizer dedicated to delivering advances in treatment and care for people living with HIV, has announced 24-week data from the phase III SAILING (ING111762) study evaluating the investigational integrase inhibitor dolutegravir in patients with HIV-1 who are failing on current therapy, but had not been treated with an integrase inhibitor.

At 24 weeks, 79% of study participants receiving the once-daily dolutegravir regimen were virologically suppressed (HIV-1 RNA <50 c/mL) vs. 70% of participants on the twice-daily raltegravir regimen. This difference in response was statistically significant with a 95% confidence interval for the difference of 3.4% to 15.9% (p=0.003).

The SAILING study was designed to demonstrate non-inferiority of a regimen containing dolutegravir versus raltegravir (both with up to two background agents) and the analysis met this criterion; statistical superiority was concluded as part of a pre-specified testing procedure. These data were presented at the 20th Conference on Retroviruses and Opportunistic Infections (CROI) in Atlanta, Georgia.

Differences in treatment outcome in favour of the dolutegravir arm were driven by greater virologic response: at Week 24, 15% of patients receiving the dolutegravir regimen had virologic non-response vs. 24% of patients receiving the raltegravir regimen.  In addition, fewer subjects failed therapy with integrase inhibitor resistance on dolutegravir (n=2) than on raltegravir (n=10, p=0.016).

Overall, the tolerability of dolutegravir (DTG) was similar to that of raltegravir (RAL). At 24 weeks, 2% of subjects on the dolutegravir regimen discontinued due to adverse events (AEs) vs. 4% of subjects on the raltegravir regimen. The rate of drug-related AEs was similar for both arms (DTG 20%, RAL 23%) and commonly reported AEs (defined as events that occurred in more than 10% of subjects) were similar on both arms, namely diarrhoea (20% DTG, 17% RAL) and upper respiratory tract infection (11% DTG, 8% RAL).

“People living with HIV who have developed resistance to more than one antiretroviral drug class face increasingly narrow treatment options and clinical decisions become increasingly complex. We welcome these initial results supporting the efficacy and tolerability of dolutegravir as a potentially useful addition in the management of HIV in treatment-experienced patients.” said John Pottage, chief scientific and medical officer, ViiV Healthcare.  “These encouraging data were included as part of the comprehensive clinical data package supporting recent regulatory submissions for dolutegravir and we look forward to receiving the primary analysis at 48 weeks in due course.”

The primary objective of the ongoing double-blind, double-dummy phase III SAILING study is to demonstrate the antiviral activity of once-daily dolutegravir 50mg compared to twice-daily raltegravir 400mg over 48 weeks in HIV-1 infected, antiretroviral-experienced, integrase inhibitor-naïve adults. At baseline, 715 study participants were randomised 1:1 to receive either dolutegravir or raltegravir plus investigator-selected background regimen of no more than 2 agents, one of which was fully active. All subjects had documented genotypic or phenotypic resistance to agents from at least two antiretroviral therapy drug classes, and ongoing virologic replication.  Median baseline HIV-1 RNA levels were 4.18 log10 c/mL and median baseline CD4+ cell counts were 200 cells/mm3. The study population included 32% women, 42% were of African American/African heritage, and 46% of study participants were classified as CDC Class C (patients who have one or more AIDS-defining illness). The 48-week primary analysis of this study will be presented at a future scientific meeting.

S/GSK1349572 (dolutegravir, DTG) is an investigational integrase inhibitor currently in development for the treatment of HIV; it does not require an additional pharmacokinetic boosting drug to be added to the regimen. Integrase inhibitors block HIV replication by preventing the viral DNA from integrating into the genetic material of human immune cells (T-cells). This step is essential in the HIV replication cycle and is also responsible for establishing chronic infection.

SAILING is the fourth phase III dolutegravir study reporting in 2012 and 2013. Data from the two studies in treatment-naïve populations, SPRING-2 (ING113086) and SINGLE (ING114467), were announced in April and July of 2012 respectively. Data from VIKING-3 (ING112574) in integrase inhibitor-resistant patients were announced in November 2012. Dolutegravir is not yet approved as a treatment for HIV or any other indication anywhere in the world.