The FDA detailed how sponsors can support the effectiveness of investigational new drugs or new drug uses for treatment of certain rare diseases, in final guidance released on March 13.
The guidance is aimed at replacement or corrective therapies targeting rare diseases that are slowly progressive, low-prevalence rare diseases that result from defects in a single enzyme. The final document includes several new elements that were not in the draft guidance the agency released in July 2018.
“There are many reasons that make demonstrating effectiveness extremely challenging” for drugs intended to treat such rare diseases, the agency said. For example, replacement enzymes may penetrate different tissues to a different extent, which may result in differences in response to treatment in the tissues.