GlaxoSmithKline plc (GSK) - Get Report said Monday that it's agreed to buy ovarian cancer drug specialists Tesaro Inc. (TSRO) - Get Report for around $5.1 billion in cash, but cautioned that it wouldn't add to the pharma giant's bottom line until 2022.

GlaxoSmithKline said it will pay $75 a share for the Waltham, Mass.-based Tesaro, a 110% premium to the 30-day moving average of its share price, and said the deal will hit its near-term earnings by a "mid to high" single digit percentage, but will start to add to its adjusted bottom line by 2022. However, the group said it won't change its shareholder return policies and expects to pay an 80 pence per share dividend for the 2018 financial year.

"The acquisition of TESARO will strengthen our pharmaceuticals business by accelerating the build of our oncology pipeline and commercial footprint, along with providing access to new scientific capabilities," said CEO Emma Walmsley. "This combination will support our aim to deliver long-term sustainable growth and is consistent with our capital allocation priorities. We look forward to working with TESARO's talented team to bring valuable new medicines to patients."

Tesaro shares surged 59 % to $73.72 each following news of the deal, while GlaxoSmithKline fell 7.5% in London to change hands at a session low of £15.00 each.

"This transaction marks the beginning of a new global partnership that will accelerate our oncology business and allow our mission of delivering transformative products to individuals living with cancer to endure," said CEO Lonnie Moulder. "Our Board and Management team are very pleased to announce this transaction, and we are grateful to the management team at GSK for their tremendous vision and the opportunity to preserve and build upon the impact we have had in the cancer community to date."

GlaxoSmithKline's play for Tesaro comes just hours after the London-based group agreed to sell its Horlicks nutrition business in India to Unilever for $3.8 billion, which topped competing offers from Neslte SA (NSRGY) - Get Report   and Coca-Cola Co. (KO) - Get Report for the malted drink. CEO Walmsley said proceeds from sales such as Horlicks will help fund the group's growth in the pharmaceutical space, including the Tesaro acquisition.