Amgen has entered into a definitive agreement with GSK to reacquire all of its remaining rights to bone drugs Prolia (denosumab) and Xgeva (denosumab) and cancer therapy Vectibix (panitumumab) in 48 countries around the globe.

GSK has held select regional rights to Prolia and Xgeva since 2009 and to Vectibix since 2010 under license from Amgen. In 2014, these combined licenses generated sales of around $111 million for GSK, which Amgen is expecting to boost its books by 2017.

Under the terms of the deal, Amgen will make undisclosed milestone payments to GSK on signing and on the successful rehoming of these products, after which the US biotech giant will book all product sales.

"This unique agreement with GSK allows Amgen to regain rights to three important growth products, and to directly serve more patients in key expansion markets," noted chairman Robert Bradway, and it also allows the firm to build additional commercial infrastructure in oncology and bone health, two strategically important therapeutic areas with emerging late-stage pipeline assets.

GSK will continue to hold the license and sell and distribute the products for an interim transition period that will vary by country, but the majority of markets are planned to be transitioned back to Amgen within 12 months.