Rare disease is a general term for a group of diseases with a very low incidence, also known as orphan disease. According to the World Health Organization (WHO), diseases with 0.065% to 0.1% of the total population can be defined as rare diseases. However, all countries in the world according to their own specific conditions, there are some differences  in the identification of rare diseases. For example, the United States defines rare disease as a disease with less than 200,000 patients (or less than 1/1500) a year; Japan defines rare disease as having less than 50,000 illnesses (or a 1/2500); Europe defines a disease with a disease incidence of less than 1/2000 as a rare disease. There is no clear definition of rare diseases in China, but the consensus generally reached by many experts is that the prevalence of adults is less than one in 500,000 and the incidence of neonatal diseases less than one in 10,000 may be regarded as rare.

It is understood that there are more than 7,000 kinds of rare diseases known to date, accounting for about 10% of human diseases. The number of rare diseases in China has reached 20 million. Of these rare diseases, 80% are inherited diseases, of which 50% are neurological genetic diseases.

Orphan Drugs, a drug used to prevent, treat and diagnose rare diseases, initially characterized by the low number of orphan drugs suitable for orphan drugs due to the low prevalence of rare diseases, coupled with the difficulty of developing orphan drugs , A great initial investment, many pharmaceutical companies take into account the issue of return on investment, research and development is not active, or even reluctant to get involved in the field.

America

As early as 1983, the United States enacted the "Orphan Drug Act" and later introduced the special treatment of orphan drug evaluation. Coupled with a series of supportive policies such as preferential tax policies, financial support for clinical trials and the market exclusive period extension, the awareness of orphan medicine has been increasing constantly. The enthusiasm of the pharmaceutical companies in the development of orphan medicine has been increasing year by year and its enthusiasm has not diminished.

Now the economic benefits brought by the small orphan medicine can not be underestimated. The treatment of rare diseases has become one of the most profitable sectors in the pharmaceutical industry. Many international large-scale pharmaceutical companies have stepped up R & D investment in rare diseases in recent years, The leading orphan drug market is not just the veteran Novartis, Roche, Johnson & Johnson, Pfizer, Bristol-Myers Squibb, Merck and other multinational companies, but also a rising star of new medical, Albert, Shire, 2016 the world's best-selling orphan Revlimid, the drug for new-based medicine, has more than $ 7 billion in global sales in 2016 and more than $ 4 billion in sales in the United States. Evaluate Pharma's 2017 Orphan Drugs Report also mentioned that global total sales of orphan drugs are expected to reach 209 billion U.S. dollars in 2022 and 21.4% in the prescription drug market (excluding generic drugs); growth rate (2017 to 2022 Year compound annual growth rate of +11.1%) will be the entire prescription drug market twice.

In 2017, a total of 22 orphan medicines were included in the original FDA approved new drug (including NME and BLA). (See Table 1 for details)

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Table 1 2017 orphan drugs approved by the FDA for new drugs