In a deal worth around $32 billion, Irish drug maker Shire – headquartered in Dublin but managed from Boston, Massachusetts – has agreed a takeover of US biopharmaceutical company Baxalta, spun off last year from Baxter International.

The offer, to be secured with an $18 billion credit facility to be financed through a debt issue, translates to a value of $45.57 for each Baxalta share, a premium of about 37.5%. Shire had offered approximately $30 billion in an initial approach for the company last August.

The latest price is 37.5% above Baxalta's price on Aug. 3, before Shire publicly revealed its interest. Baxalta rejected Shire's previous $30 billion all-stock offer in August, arguing it significantly undervalued the company.

Both companies boards’ have agreed to the merger, which is expected to close in the middle of this year.

Shire CEO Flemming Ornskov said the merged company would have leadership positions in multiple, high-value franchises with anticipated annual revenues of more than $20 billion by 2020.

The deal would also create a global leader in rare diseases with products touted as best-in-class products in hematology, immunology, neuroscience, lysosomal storage diseases, gastrointestinal/endocrine diseases and hereditary angioedema.

The company’s portfolio would include more than 60 programs in development, more than 50 of these for rare diseases, as well as the newly approved Baxalta products Adynovate, Vonvendi and Obizur.

Shire expects more than 30 recent and planned product launches from the merged pipeline, contributing around $5 billion in annual revenues by 2020. Annual cost synergies amounting to more than $500 million are expected to be realized within the first three years, and the transaction is expected to be accretive to earnings in 2017.

In a separate deal announced earlier, Baxalta has agreed with Symphogen an immuno-oncology collaboration that could be worth up to $1.6 billion. The partners will advance novel therapeutics against six targets, with the first program due to enter clinical studies in 2017.

Following the successful completion of phase 1 trials, Baxalta will gain exclusive rights to complete late-stage development and global commercialization.

Immuno-oncology, which focuses on activating and directing immune systems against tumor growth, is generating promising new therapies that research shows could significantly improve outcomes for several cancers.