Novartis AG has proposed buying radiopharmaceuticals specialist Advanced Accelerator Applications SA (AAA) in a deal valuing the company at $3.9 billion. The transaction would add the EU-approved neuroendocrine tumor therapy Lutathera (lutetium [177Lu] oxodotreotide) to the company's portfolio, as well as a new technology platform that Novartis said has potential applications across a number of early oncology development programs.