What is a Complete Response Letter (CRL)?

A Complete Response Letter is an FDA communication with a manufacturer rejecting approval of a drug following review of a new drug application (NDA). A CRL can be issued for not satisfactorily meeting any number of conditions needed for drug approval including concerns about data, risk-benefit of the drug, manufacturing sites, etc. CRLs are shared in confidence with manufacturers so reasons for the rejection are not known publicly unless a company decides to share the information voluntarily. A CRL does not preclude a company from resubmitting a drug application and it is common to see resubmissions upon addressing FDA concerns.