AbbVie has entered a definitive agreement to acquire Pharmacyclics in a transaction valued at approximately $21 billion, gaining its flagship asset Imbruvica (ibrutinib) for hematologic malignancies. The acquisition expands AbbVie’s clinical and commercial presence in oncology. The transaction, subject to customary closing conditions, is expected to close in mid-2015. Imbruvica is a Bruton’s tyrosine kinase (BTK) inhibitor approved for four indications to treat three different type...