Orphan drug
A drug for a rare disease (in the US, fewer than 200,000 patients) that gets extra incentives, tax credits, fee waivers and seven years of market exclusivity, to make development worthwhile. Most cancers qualify, so most cancer drugs are orphans.
The US Orphan Drug Act of 1983 and its EU equivalent in 2000 were designed for neglected diseases, but because cancer is subdivided into many molecularly and anatomically defined groups, each individually rare, around 40% of new cancer drugs now carry orphan status, some of them blockbusters. The incentives have clearly accelerated drugs for rare cancers such as GIST, CML and mesothelioma, and critics argue they are also gamed by 'salami-slicing' indications and contribute to high prices. Orphan status is separate from the accelerated, breakthrough and priority pathways that speed review.