Ultragenyx · Nasdaq: RARE · UX111 (rebisufligene etisparvovec)

The 8-K says the letter concerns CMC and facility-inspection observations, which the company says are readily addressable. It does not mention the letter's statement that the corrective actions do not appear comprehensive enough to address systemic issues, or the Form 483s.

The letter says “Your corrective actions do not appear to be comprehensive enough to address the systemic issues observed during the inspection” [FDA · Jul 7 · p. 1]. The 8-K says “The Company believes that these observations are readily addressable, related to facilities and processes, and are not directly related to the quality of the product” [8-K · Jul 11]. The 8-K does not mention systemic issues or the adequacy of the corrective actions, [8-K · searched] and the word does not appear in the later filings searched. [Later filings · searched]

The 8-K describes “additional information and improvements related to specific aspects of chemistry, manufacturing and controls (“CMC”) and observations from the recently completed manufacturing facility inspections” [8-K · Jul 11]. It does not mention the Form FDA 483s, Current Good Manufacturing Practice or a follow-up inspection. [8-K · searched] The 10-Q of Aug 6, 2025 says the inspections were at “our gene therapy manufacturing facility and that of our third-party manufacturer” [10-Q · Aug 6].

On the clinical side, the letter says “We are currently evaluating the clinical data to determine if it adequately supports the proposed indication” [FDA · Jul 7 · p. 17]; the 8-K says “The CRL did not note any review issues related to the clinical data package nor clinical inspections” [8-K · Jul 11], and that it “asked that updated clinical data from current patients be included in the resubmission” [8-K · Jul 11].

The company resubmitted in January 2026, was given a September 19, 2026 action date, and reported approval and a priority review voucher on September 17, 2026. Its August 2025 10-Q said the FDA will cease awarding vouchers after September 30, 2026.

On Jul 11, 2025 the 8-K said “Once resolution is achieved, the Company expects to resubmit the BLA and anticipates up to a six-month review period to follow the resubmission” [8-K · Jul 11]. In August it said it “will work with the FDA through a Type A meeting to agree on the planned resolution of the observations” [8-K · Aug 5]; in November, “The company plans to resubmit the BLA early in 2026” [8-K · Nov 4].

The resubmission was announced on Jan 30, 2026, “with a PDUFA date expected in the third quarter of 2026” [8-K · Jan 30]; in April, “The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026” [8-K · Apr 2].

On vouchers, the company's 10-Q of Aug 6, 2025 says it sold two earlier vouchers “for an average amount of $105.3 million for each PRV” [10-Q · Aug 6], and that “the FDA will cease awarding PRVs after September 30, 2026” [10-Q · Aug 6]. On Sep 17, 2026 the company reported “standard full approval” [8-K · Sep 17] and said “The Company received a Priority Review Voucher upon this approval.” [8-K · Sep 17]

The three deficiencies that can be read in the letter are all manufacturing (CMC) findings from pre-license inspections. Pages 3 to 7 are redacted. Under clinical, the letter says the FDA was still evaluating the data.

The letter says the FDA “cannot grant final approval because of the deficiencies outlined below” [FDA · Jul 7 · p. 1], under the heading “Chemistry, Manufacturing, and Controls (CMC)” [FDA · Jul 7 · p. 1].

Each of the three numbered deficiencies follows a pre-license inspection after which CBER issued a “Form FDA 483, List of Inspectional Observations” [FDA · Jul 7 · p. 1]. For each, the letter says the company's responses “do not sufficiently address the deficiencies noted during the inspection” [FDA · Jul 7 · p. 1], that “Your corrective actions do not appear to be comprehensive enough to address the systemic issues observed during the inspection” [FDA · Jul 7 · p. 1], and that the corrections “may require additional review and verification” [FDA · Jul 7 · p. 2] at a later inspection and “therefore remain unresolved” [FDA · Jul 7 · p. 2]. The first two inspections are of “Ultragenyx Pharmaceutical Inc.” [FDA · Jul 7 · p. 1]; the third reads “CBER conducted a pre-license inspection (PLI) of , and issued” [FDA · Jul 7 · p. 2].

Pages 3 to 7 contain only the redaction code “(b) (4)” [FDA · Jul 7 · p. 3]. The numbering resumes at 9 under “ADDITIONAL COMMENTS” [FDA · Jul 7 · p. 8]. Under clinical, the letter says “We are currently evaluating the clinical data to determine if it adequately supports the proposed indication” [FDA · Jul 7 · p. 17] and asks, “With your resubmission, please provide updated safety and efficacy data” [FDA · Jul 7 · p. 17].

A resubmission “must fully address all the deficiencies listed” [FDA · Jul 7 · p. 17].

The company resubmitted in January 2026 with responses to the CMC observations, seeking accelerated approval. On September 17, 2026 it reported standard full approval.

The letter said a resubmission “must fully address all the deficiencies listed” [FDA · Jul 7 · p. 17]. The company's Jan 30, 2026 8-K says the resubmitted BLA “includes comprehensive responses to chemistry, manufacturing, and controls (CMC)-related observations outlined in a Complete Response Letter” [8-K · Jan 30], and that it was “seeking accelerated approval” [8-K · Jan 30].

On Sep 17, 2026 the company announced the FDA “granted standard full approval of FAYUVI™ (rebisufligene etisparvovec-hopf), also known as UX111” [8-K · Sep 17]. Not in this record: the FDA's approval letter and label, what the company does with the voucher, and filings after Sep 17, 2026. [not in record]