The Food and Drug Administration took an unprecedented step toward regulatory transparency on Thursday by publishing more than 200 Complete Response Letters (CRLs) that detail why the agency initially rejected drug and biological product applications between 2020 and 2024.
The published letters focus exclusively on applications that were eventually approved after sponsors addressed the FDA's concerns. By compiling these previously scattered documents into a centralized database, the agency aims to provide greater insight into its decision-making process and help reduce uncertainty for drug developers.
Breaking Down Regulatory Opacity
"For far too long, drug developers have been playing a guessing game when navigating the FDA," FDA Commissioner Marty Makary, MD, MPH, said in a statement. "Drug developers and capital markets alike want predictability. So today we're one step closer to delivering it to them, with an ultimate goal of bringing cures and meaningful treatments to patients faster."
CRLs are issued when the FDA completes its review cycle but determines it cannot approve an application in its current form. The agency most frequently cites safety and efficacy concerns, manufacturing deficiencies, and bioequivalence issues as reasons for rejection. These deficiencies are detailed in the letters along with recommendations for addressing them.
Addressing Industry-Wide Communication Gaps
The transparency initiative addresses a significant communication problem that has plagued the pharmaceutical industry for years. According to a 2015 analysis conducted by FDA researchers, sponsors avoided mentioning 85% of the FDA's concerns about safety and efficacy when publicly announcing their applications were not approved. When the agency calls for new clinical trials for safety or efficacy reasons, that information goes undisclosed approximately 40% of the time.
This lack of transparency has created a cycle where lessons learned from non-approvals are not shared within the industry, leading companies to repeatedly make similar mistakes, the FDA noted.
Recent High-Profile Rejections
The database includes several notable recent CRLs, including Unicycive Therapeutics' New Drug Application for oxylanthanum carbonate for treating hyperphosphatemia in chronic kidney disease patients on dialysis, and Regeneron's supplemental Biologic License Application for an extended 24-week dosing duration for aflibercept 8 mg (EYLEA HD) in wet age-related macular degeneration, diabetic macular edema, and diabetic retinopathy.
Other included rejections involve Aldeyra Therapeutics' resubmission of an NDA for reproxalap for dry eye disease and Milestone Pharmaceutical's application for etripamil nasal spray (Cardamyst) for paroxysmal supraventricular tachycardia treatment.
Database Access and Future Plans
The initial batch of published decision letters is accessible through openFDA, described as the first centralized database of past CRLs. The documents have been redacted to protect trade secrets and confidential commercial information, and the agency is currently working to publish additional CRLs from its archives.
While Thursday's release represents a significant step forward, there remains considerable interest in CRLs for products that were never approved—documents that have traditionally not been released and would provide even greater insight into the FDA's decision-making process.
