On Thursday, the U.S. Food and Drug Administration approved Ultragenyx Pharmaceutical Inc. (RARE)'s Fayuvi (rebisufligene etisparvovec-hopf, UX111) for pediatric patients with mucopolysaccharidosis type IIIA (MPS IIIA, Sanfilippo syndrome Type A).

Financial Impact and Priority Review Voucher

Fayuvi is the first-ever FDA-approved treatment for Sanfilippo syndrome Type A, a progressive and fatal neurodegenerative disease, and the second gene therapy and sixth FDA approval overall for Ultragenyx.

The company received a Priority Review Voucher upon this approval, which is expected to significantly bolster the company's balance sheet given the market rate for PRVs is around $200 million.

William Blair sees the approval of Fayuvi as an incremental positive, but sees a lack of key value inflection points for the company in the next 12 months and therefore rates the stock Market Perform.

The company stated that the wholesale acquisition cost for Fayuvi will be $3.95 million, and analyst Sami Corwin currently models $325 million in peak sales for Fayuvi.

Sales Force Synergy and Commercial Strategy

The management highlighted that there is more than a 75% overlap between Doljovi, Mepsevii, and Genglycos prescribers, indicating that the current sales force will support the Fayuvi launch.

The company indicated that there are approximately 300 to 400 Sanfilippo patients identified in the US.

While Ultragenyx did not provide specific numbers, it indicated there are several patients identified that are ready to receive treatment in the U.S.

In terms of ex-U.S. launches, the company indicated that it plans to submit a regulatory filing in European territories soon while also highlighting that it has received strong patient interest from Middle Eastern territories.

In August, the FDA granted accelerated approval to Ultragenyx's gene therapy, Genglycos (pariglasgene brecaparvovec-opnr, or DTX401), as the first-ever FDA-approved treatment for Glycogen Storage Disease Type Ia (GSDIa).

RARE Price Action: Ultragenyx Pharmaceutical shares were up 1.03% at $14.65 during premarket trading on Friday, according to market data.