Takeda has announced its intention to buy US drugmaker Ariad for around $5.2 billion, in a move designed to boost its oncology offering.

The firms have entered into an exclusive definitive agreement under which the Japanese drugs giant will buy all of the outstanding shares in Ariad for $24.00 per share in cash.

The move gives Takeda access to Ariad's Iclusig (ponatinib), which is cleared for the treatment of certain patients with chronic myeloid leukaemia and acute lymphoblastic leukaemia, and is forecast to generate sales for up to $180 million for 2016.

Further back in the pipeline, investigational targeted therapy brigatinib has the potential to add a differentiated, global therapy in a genetically-defined subpopulation of non-small cell lung cancer (NSCLC), the firm noted.

"The acquisition of Ariad is a unique opportunity that will enable us to positively impact the lives of more patients worldwide, advance our strategic priorities and generate attractive returns for our shareholders," said Christophe Weber, Takeda's president and chief executive. "Opportunities to acquire such high-quality, complementary targeted therapies do not come often."

According to Takeda, the move will "provide immediate revenue, bring considerable long-term revenue potential and deliver synergy savings".

The deal, which represents a premium of about 75 percent to Ariad's closing share price on January 6, has been cleared by the boards of directors of both companies and is expected to close by the end of February.

Takeda projects the acquisition to be accretive to underlying core earnings by FY2018 and broadly neutral in FY2017.