Complete response letter (CRL)

A complete response letter (CRL) is the document the FDA issues at the end of a review cycle when it decides not to approve an NDA or BLA as submitted. It lists the deficiencies the company must address and, where possible, recommends what it would take to fix them.

How it works

A CRL is not necessarily a final rejection. The sponsor can resubmit after addressing the issues, request a meeting with the FDA, or withdraw the application. Resubmissions are classified by scope:

• Class 1: minor issues such as labeling or safety update data, with a 2-month review goal.
• Class 2: everything else, including new clinical data or facility reinspection, with a 6-month review goal.

Deficiencies fall into rough buckets: clinical (efficacy or safety not established, sometimes requiring a new trial), manufacturing or CMC (chemistry, manufacturing and controls), and facility inspection findings, including problems at third-party manufacturers.

Historically, companies chose what to disclose about their CRLs. In 2025 the FDA began publicly releasing complete response letters, making it easier to compare company summaries with the agency's actual language.

Why it matters for traders

A CRL is usually the worst-case outcome on a PDUFA date, and single-asset biotechs can lose half or more of their value in a day. The details drive the recovery:

• Manufacturing-only CRLs are often viewed as fixable within months.
• Requests for a new trial can mean years of delay and new financing needs.
• Company framing vs. the letter. Compare the press release with the FDA's published text.

Example

Northwind Therapeutics (NWTX) receives a CRL citing only inspection findings at its contract manufacturer. Shares fall 35% from $40 to $26. After the site is remediated, NWTX files a Class 2 resubmission, setting a new goal date six months out.

FAQ

Is a CRL the same as a rejection?

It means the application cannot be approved as submitted, but the company can fix the deficiencies and resubmit.

How long after a CRL can a drug be approved?

It depends on the issues. A Class 1 resubmission has a 2-month review goal and a Class 2 has 6 months, plus whatever time is needed to fix the problems first.