AstraZeneca said on Tuesday it will buy clinical-stage biopharmaceutical company Fusion Pharmaceuticals Inc for about $2 billion in cash to boost its oncology portfolio. The drugmaker will pay $21 per Fusion share, a premium of more than 97 per cent to the U.S.-listed company's closing price on Monday.

AstraZeneca will also pay a non-transferable contingent value right of $3 per share, taking the combined transaction value to about $2.4 billion. Fusion, which is developing "next-generation" radioconjugates (RCs) to treat cancer, will become a wholly-owned subsidiary of AstraZeneca, with operations continuing in Canada and the U.S., it said. RCs have emerged as a promising modality in cancer treatment over recent years, AstraZeneca said.