ViiV Healthcare, a global specialist HIV company dedicated to delivering advances in treatment and care for people living with HIV, and research-driven pharmaceutical company, Shionogi & Co., Ltd. have received the initial results from the SPRING-2 (ING113086) phase III study of the investigational integrase inhibitor dolutegravir in treatment-naïve adults with HIV-1.

The study met its primary objective, demonstrating non-inferiority of dolutegravir to raltegravir. Through 48 weeks, 88% of study participants on dolutegravir were virologically suppressed (<50 copies/mL) vs. 85% of participants on raltegravir [with a 95% confidence interval (CI) for the difference, -2.2% to + 7.1%; the lower end of the CI (-2.2%) was above the prespecified -10% non-inferiority limit].

SPRING-2 is an ongoing non-inferiority study designed to compare the efficacy and safety of dolutegravir 50mg administered once-daily versus raltegravir 400mg administered twice daily, both with two nucleoside reverse transcriptase inhibitors(NRTIs); 411 treatment-naïve study participants were randomised in each arm. The primary endpoint of the study was the proportion of study participants with undetectable HIV-1 RNA (<50c/mL) through 48 weeks. The tolerability of dolutegravir was similar to that of raltegravir, with rates of adverse events leading to withdrawal at 2% in both arms. Drug-related nausea was reported by 10% of patients in each arm; no other adverse events related to study medication were reported by more than 5% of participants in either arm.

“The SPRING-2 findings indicate that once daily unboosted dolutegravir may offer people living with HIV an additional treatment option in the future. These are the first large-scale safety and efficacy data in naïve patients, and we look forward to seeing further data in 2012 to build a more comprehensive picture of the role of dolutegravir,” said Dr John Pottage, chief medical officer, ViiV Healthcare.

“At ViiV Healthcare we have a total focus on the needs of people living with HIV, and as a result we see the continued need for new, effective and convenient therapies. We are committed to building connections and collaborations, like the Shionogi-ViiV Healthcare dolutegravir programme, to meet these needs,” said Dr Dominique Limet, CEO, ViiV Healthcare.

“The SPRING-2 study has met its primary endpoint for dolutegravir in treatment-naïve patients. This marks an important milestone for the development of dolutegravir and the Shionogi-ViiV Healthcare joint venture. We look forward to completing further phase III studies in a variety of clinical settings in order to fully understand the potential clinical benefit for a range of HIV patient populations,” said Dr Tsutae "Den" Nagata, chief medical officer, Shionogi & Co., Ltd.

SPRING-2 is the first of four Phase III studies that are due to be reported in 2012. Data from the clinical trials SINGLE (ING114467), VIKING-3 (ING112574) and SAILING (ING111762), will be received throughout the year and will allow further determination of the profile of dolutegravir.  These studies are designed to support a future regulatory file for dolutegravir.

SPRING-2 (ING113086) is a phase III, randomized, double-blind, multicentre, parallel group, non-inferiority study. The study included 822 HIV-1 infected treatment-naïve participants. The study compares the efficacy and safety of dolutegravir and raltegravir as part of an overall treatment regimen; both treatment arms are administered with investigator-selected dual nucleoside reverse transcriptase inhibitor therapy (either abacavir + lamivudine or tenofovir + emtricitabine).

The primary objective for SPRING-2 is to demonstrate the antiviral activity of dolutegravir 50mg administered once-daily compared to raltegravir 400mg administered twice daily over 48-weeks. Secondary objectives include the assessment of antiviral activity of dolutegravir compared to raltegravir at 96-weeks, to compare the tolerability, long-term safety and antiviral and immunologic activity of dolutegravir to raltegravir and to evaluate viral resistance in study participants experiencing virological failure.

S/GSK1349572 (dolutegravir) is an investigational integrase inhibitor (INI) currently in development by Shionogi-ViiV Healthcare LLC for the treatment of HIV. It is currently the only once-daily, unboosted INI in Phase III clinical development. 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. Given the stage of development of this investigational HIV therapy, the full picture of the efficacy and safety of dolutegravir has not been conclusively determined.

The Shionogi-ViiV Healthcare LLC is a joint venture between Shionogi & Co., Ltd. and ViiV Healthcare Ltd., a global company with a sole focus on HIV. Dolutegravir is the lead compound in the Shionogi-ViiV Healthcare LLC partnership. Shionogi-ViiVHealthcare LLC is also developing another integrase inhibitor which is at an earlier stage of development.