Rare Disease Effectiveness Guidance

FDA has published a draft guidance, Slowly Progressive, Low-Prevalence Rare Diseases with Substrate Deposition That Results from Single Enzyme Defects: Providing Evidence of Effectiveness for Replacement or Corrective Therapies, to give guidance to sponsors on the evidence necessary to demonstrate the effectiveness of new drugs or new drug uses intended for slowly progressive, low-prevalence rare diseases associated with substrate deposition and caused by single enzyme defects. The document does not apply to: 

•          low-prevalence rare diseases with rapidly progressive clinical courses; and
•          low-prevalence rare diseases with previously characterized endpoints predictive of clinical benefit.

The agency says it encourages sponsors to discuss with the relevant review divisions whether the approach outlined in the guidance applies to their specific drug development programs.