Pfizer Inc. (NYSE: PFE) said on Monday it has received a Refusal-to-File letter from the United States Food and Drug Administration (FDA) for tafamidis, the company’s oral investigational compound for patients with Transthyretin Familial Amyloid Polyneuropathy (TTR-FAP).

Usually manifesting itself between 20 and 40 years of age, FAP is characterized by the systemic deposition of amyloidogenic variants of the transthyretin protein, especially in the peripheral nervous system, causing a progressive sensory and motorial polyneuropathy.

Upon preliminary review, the FDA determined that the application was not sufficiently complete to permit a substantive review. If it determines that the NDA is not sufficiently complete, the U.S. health regulator issues a refuse to file letter to the applicant.

The company said additional information needed to support this filing is available without further clinical studies.

Pfizer said it is working closely with the FDA to resubmit the application as quickly as possible.

A Refusal to File letter does not provide comment on the acceptability of the clinical data, and no judgment was made on the efficacy or safety of tafamidis as part of the letter.

Shares of Pfizer ended Friday's regular trading at $20.38.