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Complete response letter

A Complete Response Letter is a regulatory action by the US Food and Drug Administration in response to a New Drug Application or a Biologics License Application, indicating that the application will not be approved in its present form[1].

Under the Prescription Drug User Fee Act, the FDA has a limited timespan, known as the PDUFA date, to decide on an application, and it may either approve the application or issue a Complete Response Letter[2]. Grounds for issuing one may include labeling issues, current Good Manufacturing Practice concerns or concerns about the safety or effectiveness of the drug[3].

A sponsor that receives a Complete Response Letter may withdraw the application, request a hearing or resubmit the application[1]. Hearings are open to the public, so this route is relatively rarely chosen[4].

FDA policy classifies resubmissions following a Complete Response Letter as Class 1 or Class 2[5]. If a response is complete, it is classified within 30 days[6]. A Class 1 response typically denotes minor amendments, such as labeling, assay validation data or minor re-analysis of the data, while a Class 2 response typically involves more extensive concerns and/or a reinspection[6]. A Class 1 response is typically handled within 3 months and a Class 2 response within 6 months[5].

Why it matters to investors

When the FDA decides an application within the time set by the PDUFA date, it may either approve the application or issue a Complete Response Letter[2]. Complete Response Letters are typically not disclosed publicly because they often include proprietary information, and company press releases typically leave out most of the details, including the reasons[7][8].

Related: New Drug Application (NDA), Biologics License Application (BLA)

Sources

  1. "21 CFR 314.110" . www.accessdata.fda.gov . Archived from the original on November 28, 2002 . Retrieved 2021-06-30 . web.archive.org (via Wikipedia: Complete Response Letter)
  2. Thayer, Ann M. (15 May 2017). "The complete response letter: The mail no one wants to receive" . ACS C&EN . Retrieved 2021-06-30 . cen.acs.org (via Wikipedia: Complete Response Letter)
  3. Chandanais, Ryan (8 December 2017). "Complete Response Letters: What Drug Manufacturers Hope to Avoid" . Pharmacy Times . Retrieved 2021-06-30 . pharmacytimes.com (via Wikipedia: Complete Response Letter)
  4. "FDA Complete Response Letters: The design v. reality of FDA's responses to drug applications" . Healthcare Law Insights . 2015-01-12 . Retrieved 2021-06-30 . healthcarelawinsights.com (via Wikipedia: Complete Response Letter)
  5. "MAPP 6020.5 Rev. 2: Classifying Resubmissions of original NDAs, BLAs and Efficacy Cupplements in Response to Complete Response Letters" . Food and Drug Administration, Center for Drug Evaluation and Research . Retrieved 2021-06-30 . fda.gov (via Wikipedia: Complete Response Letter)
  6. "MAPPing Out The Timing Of A Complete Response Submission" . Camargo . 27 February 2015 . Retrieved 2021-06-30 . camargopharma.com (via Wikipedia: Complete Response Letter)
  7. Mullard, Asher (2015-07-01). "Should the FDA disclose complete response letters?" . Nature Reviews Drug Discovery . 14 (7): 449. doi : 10.1038/nrd4686 . ISSN 1474-1784 . S2CID 34872830 . doi.org (via Wikipedia: Complete Response Letter)
  8. Lurie, Peter; Chahal, Harinder S.; Sigelman, Daniel W.; Stacy, Sylvie; Sclar, Joshua; Ddamulira, Barbara (2015-06-10). "Comparison of content of FDA letters not approving applications for new drugs and associated public announcements from sponsors: cross sectional study" . BMJ . 350 h2758. doi : 10.1136/bmj.h2758 . ISSN 1756-1833 . PMC 4462714 . PMID 26063327 . bmj.com (via Wikipedia: Complete Response Letter)

Checked 8 October 2026. How we check sources