AstraZeneca is to buy 55 per cent of privately held biotech firm Acerta Pharma for $4 billion to give it access to a new kind of blood cancer drug, boosting its long-term growth at the cost of a near-term hit to earnings. It is a lofty price but AstraZeneca believes acalabrutinib could sell more than $5 billion a year, supporting its return to growth and completing the transformation of the drugmaker's oncology business. By doing a dilutive acquisition we don't make our lives easier in the short term but we are committed to our stated goals and we will manage through, Chief Executive Pascal Soriot told reporters on Thursday.