GlaxoSmithKline (GSK) and Pfizer's HIV joint venture ViiV Healthcare has revised its alliance with Shionogi focusing on integrase inhibitors, including lead drug candidate dolutegravir.
ViiV was set up by GSK and Pfizer in 2009 and shortly thereafter formed another joint venture with Japanese drugmaker Shionogi to advance the integrase inhibitor programme.
The revised terms mean that ViiV effectively acquires global development and commercialisation rights to the Shionogi-ViiV joint venture, with the Japanese company receiving a high-teens royalty on sales in return and a 10 per cent stake in ViiV.
The net effect of the agreement means that GSK's share of ViiV drops from 85 per cent to 76.5 per cent, while Pfizer's stake is reduced from 15 per cent to 13.5 per cent. GSK will add an additional 1.8 per cent in equity - taken from Pfizer's stake - if dolutegravir is approved in the US and EU.
ViiV and Shionogi's decision to rewrite the terms of the alliance comes just ahead of the first regulatory submissions for dolutegravir, which is in the same class as Merck & Co's $1.6bn blockbuster Isentress (raltegravir) and Gilead Sciences' elvitegravir.
Shionogi-ViiV completed the phase III trials programme for dolutegravir in the summer and said at the time it would file its first regulatory submissions for the drug by the end of the year.
Gilead's drug was approved in the US in August as part of four-drug HIV therapy Stribild (cobicistat/elvitegravir/emtricitabine/tenofovir) and has also been filed for approval as a single-agent product.
ViiV believes dolutegravir has certain advantages over its rivals - for example a once-daily dose was as effective as twice-daily Isentress in treatment-naïve HIV patients - and that profile has prompted some analysts to predict sales of up to $5bn at peak.
"ViiV Healthcare and Shionogi believe that now is the right time to simplify and evolve their existing arrangement," said ViiV chairman David Redfern.