AbbVie is adding substantial ballast to its pipeline through a deal to buy Pharmacyclics for a whopping $21 billion.

The moves gives AbbVie access to Pharmacyclics’ Johnson & Johnson-parterned blood cancer pill Imbruvica (ibrutinib), which pulled in annual sales of more than $500 million last year but is widely expected to achieve coveted blockbuster status by the end of 2015.

Imbruvica has already bagged four US approvals across three different types of blood cancers, including chronic lymphocytic leukemia, mantle cell lymphoma and Waldenstrom's macroglobulinemia, and AbbVie says “significant opportunity” also exists with further indications.

Pharmacyclics has three other molecules in early-stage clinical trials, giving AbbVie a “strategically compelling opportunity” that will diversify its offering and thus help reduce its reliance on autoimmune blockbuster Humira (adalimumab), which is facing competition from cheaper biosimilars.

The transaction should be “highly accretive” to both revenue and earning by 2017, AbbVie said.

Media reports suggest that J&J and Novartis were also circling to snap up the biotech.