Confronted with an expanding set of funding, regulatory, and payment challenges, biotechnology companies must focus on being more selective about the drugs they choose to develop and should join forces with other drug makers and academic researchers, executives at the industry’s biggest annual gathering said yesterday. “You have to decide where you are strong in research and development and where you need partners,’’ said Christopher A. Viehbacher, chief executive of France’s Sanofi SA, which recently bought Genzyme Corp. in Cambridge, Mass.
