[Ip-health] Orphan Drugs designations and approvals have something to say about risks | Bill of Health

James Love james.love at keionline.org
Tue Sep 26 04:04:32 PDT 2017

​This is a
2000 word
​ essay ​
on the likelihood of an FDA orphan designation for a drug receiving FDA
marketing approval.


​Orphan Drugs designations and approvals have something to say about risks
Bill of Health

September 25, 2017,

On January 5, 1983, the U.S. Orphan Drug Act became law as Public Law
97-414. Over the past 34 years the Act has been amended numerous times,
often extending or expanding the benefits, which currently include a 50
percent tax credit for qualifying clinical trials, exemptions or discounts
on prescription drug user fees, an easier and faster path to FDA approval,
and seven years of marketing exclusivity for an approved orphan indication.

The Orphan Drug Act involves a system of designations and approvals
relating to specific indications a drug will treat. A qualifying orphan
indication is one that involves 200,000 or fewer patients in the United
States, and can be based upon a subpopulation for a particular disease.

I have collected data from the FDA on all orphan designations and approvals
from the beginning of the program through September 17, 2017. These are in
a Google Sheet, available here as an html or an xlsx file. In this note, I
use the data to calculate the likelihood of FDA marketing approval, once
the FDA grants an orphan designation.

The results are then compared to estimates by others of the likelihood of
approval for drugs entering clinical testing.
. . .

The data on orphan drug designations and approvals has the advantage of
being transparent, including a large number (4350) of observations, and a
set of drugs that are increasingly important, and often extremely

. . .

In the past 33 years, the times from designation to approval have averaged
between 4 or 5 years, depending upon the period.  The likelihood of success
(approval by the FDA), once the FDA designation is granted is generally in
the range of .2 to .25, when lags of 4 or 5 years are used.

James Love.  Knowledge Ecology International
KEI DC tel: +1.202.332.2670, US Mobile: +1.202.361.3040, Geneva Mobile:
+41.76.413.6584, twitter.com/jamie_love

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