Chiron is one of the world's top biotech firms. It focuses on three areas: biopharmaceuticals, vaccines, and blood testing. Its flagship product is tobramycin solution for inhalation (TOBI), an antibiotic for cystic fibrosis patients. Proleukin, another bestseller, was the first treatment approved for metastatic kidney cancer and melanoma. Betaseron, its multiple sclerosis drug, is sold by Berlex Labs, the US affiliate of Schering, which licenses the drug for the European market (where it is known as Betaferon). The vaccines unit sells pediatric, flu, and adult infection vaccines; its blood-testing products detect HIV and other viruses. Novartis, one of Chiron's R&D partners, owns 42% of the company.