Genzyme Corp., the biotechnology company bought by French drug maker Sanofi last February for $20.1 billion, has named two new executives to head the rare disease and multiple sclerosis businesses.

Both will report to David Meeker, who was named CEO of Cambridge, Mass.-based Genzyme last month after serving as COO when the company was independent. All other businesses of Genzyme have either been sold off or absorbed into Sanofi.

Bill Sibold was recruited from Aliso Viejo,Calif.-based Avanir Pharmaceuticals (Nasdaq: AVNR), where he was the chief commercial officer. Sibold previously spent eight years at Biogen Idec (Nasdaq: BIIB), the maker of marketed multiple sclerosis therapies Avonex and Tysabri. At Biogen, he held a variety of positions including senior vice president for U.S. commercial operations. He will oversee the development of two potential treatments for MS at Genzyme, which will be marketed as Lemtrada and Aubagio if approved.

The new head of rare diseases, Dr. Rogerio Vivaldi, has been with Genzyme since 1997, and most recently served as head of the renal and endocrinology businesses, which have now been absorbed into Sanofi. He also previously served as senior vice president and president of Genzyme Latin America. Genzyme said Vivaldi treated patients with the rare Gaucher disease as early as 1992, and has written scholarly articles about the disease. He will oversee Genzyme’s stable of approved rare disease therapies, including Cerezyme for Gaucher disease, Fabrazyme for Fabry disease and Myozyme/Lumizyme for Pompe disease, as well as development stage assets.