Alexion, AstraZeneca Rare Disease, has entered a definitive purchase and license agreement with Pfizer for a portfolio of preclinical gene therapy programs and enabling technologies. The agreement adds complementary pipeline assets and innovative technologies for next-generation genomic medicines.   Alexion will purchase and license the assets of Pfizer’s early-stage rare disease gene therapy portfolio for a total consideration of up to $1 billion, plus royalties on sales. The transaction, sub...