The study, published this month in Health Affairs, concludes that legislative and regulatory efforts to promote the development of drugs to treat rare diseases has been largely successful.
In 1983, the Orphan Drug Act was passed to incentivize the development of drugs to treat rare diseases by providing sponsors with tax deductions, fee-waivers and a longer period of marketing exclusivity. In the years following, FDA has also developed numerous guidances intended to help sponsors develop orphan drugs.
Prior to the acts passage, FDA had approved only 10 drugs to treat rare diseases. However, since then, orphan drugs have accounted for a growing percentage of drug approvals. Last year, orphan drugs represented nearly half (47%) of all newly drugs approved by FDA.
Measuring Innovation
In order to compare the level of innovation for orphan drugs relative to non-orphan drugs, two researchers, Kathleen Miller and Michael Lanthier, at FDAs Office for Planning, looked at all new molecular entities (NMEs) approved by FDA between 1983 and 2014.
In that time, FDA approved a total of 843 NMEs, nearly a quarter of which (209) had orphan designation.
For most of the three decades since the Orphan Drug Act was passed, the researchers say there have several cyclical changes in the number of orphan drugs approved, with large drops in the number of orphan products approved in 1994, 2000 and between 2005 and 2006.
However, since 2010, there has been a significant increase in the number of orphan products approved, which the researchers say is driven by “a greater focus on cancer therapies, more large companies developing orphan drugs, and orphan drugs occupying a larger proportion of the overall NME pipeline.”
The researchers then broke the approvals up based on three levels of innovativeness: first-in-class, advance-in-class and addition-to-class. First-in-class products represent NMEs that are the first to be approved within a pharmacologic class, while advance-in-class drugs represent non-first-in-class NMEs that qualified for priority review. Addition-to-class drugs represent NMEs that were not first in class and did not provide enough advantage over existing treatments to warrant a priority review.
**New Molecular Entities Approved Between 1983-2014** **Category** **Orphan (N: 209)** **Non-Orphan (N: 634)** **Total: 843** First-in-class 106 (51%) 165 (26%) 271 (32%) Advance-in-class 75 (36%) 125 (20%) 200 (24%) Addition-to-class 28 (13%) 344 (54%) 372 (44%)
Based on this analysis, orphan drugs accounted for 40% of all first-in-class drug approvals since the designation was created in 1983.
When breaking orphan approvals down by therapeutic class, the researchers found drugs to treat rare cancers accounted for more than a third (35%) of orphan NME approvals, while the next largest therapeutic class, drugs to treat metabolic disorders, accounted for an eighth (12%) of orphan NME approvals.
The researchers also conclude that there are fewer “me-too” products among orphan drugs, which they say is likely a result of the small patient populations these drugs treat discouraging companies from pursuing products where there is already competition, unless they are confident in their products advantage over existing treatments.
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