FDA Grants Orphan Drug Designation, page-11

Great news, Megagane and thanks.

While not wanting to put a dampener on celebrations, I would question the following…

Importantly this now allows the FDA to priority review Neuron's drug for Rett syndrome which is very bullish for receiving breakthrough designation. Orphan drug designation bodes very well for the next step in breakthrough designation…

Priority review is something that can only applied for around the time of submitting application for marketing approval, so it doesn’t come into play at this point. Having orphan drug designation, btw, doesn’t automatically entitle its sponsor to priority review.

Also, I don’t think that receiving orphan drug designation should be construed as a bullish sign that the drug will also be granted breakthrough therapy designation. These two designations are unrelated, imo. It should be remembered that efficacy hurdles are much higher for BTD than with orphan drug designation. Orphan drug designation only requires that a medically plausible rationale be presented which suggests that the drug might have a favourable effect on the disease. One third of orphan drugs are designated on the basis of in vitro or animal data only. BTD, on the other hand, requires some sound clinical data evidence of substantial impact on one or more clinically meaningful endpoints.