Roche Holding announced Monday its $8.3 billion acquisition of InterMune, a suburban San Francisco-based company lung disease drug developer, marking the latest in a series of deals by the Swiss drug giant.

The proposed purchase of InterMune is Roche’s largest deal since its $46.8 billion takeover of Genentech in 2009, and second major deal this summer following Roche’s $1.7 billion buy of San Diego-based Seragon Pharmaceuticals in July.