4 December 2017 - US FDA approval of a new drug typically coincides with a period of patent protection, during which the manufacturer will often apply for additional indications to expand the market for the product. 

For example, the tyrosine kinase inhibitor imatinib (Gleevec; Novartis) was originally approved to treat Philadelphia chromosome–positive chronic myelogenous leukaemia, but has since been approved for treatment of other cancers. 

Many non-cancer drugs also follow this pattern, including botulinum toxin A (Botox; Allergan), which was originally approved for the treatment of strabismus and blepharospasm and subsequently approved for treatment of cervical dystonia, cosmetic uses, and chronic migraine.

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