Upstaza, one-time gene therapy, under FDA review for approval

It's under priority review, with US agency's decision due on or before Nov. 13

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The U.S. Food and Drug Administration (FDA) has agreed to review an application seeking the approval of Upstaza (eladocagene exuparvovec), PTC Therapeutics’ one-time gene therapy for AADC deficiency.

The FDA placed the company’s application under priority review, which shortens the review period to about six months from the usual 10 months. A regulatory decision is expected on or before Nov. 13.

“We are excited to be one step closer to bringing an approved therapy to patients with AADC deficiency in the United States,” Matthew B. Klein, MD, CEO of PTC, said in a company press release.

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Gene therapy designed to deliver healthy DDC gene to brain cells

AADC deficiency is caused by mutations in the DDC gene, which provides instructions to make the enzyme aromatic L-amino acid decarboxylase or AADC. This enzyme is required to make certain brain signaling molecules (neurotransmitters), including dopamine and serotonin.

The disorder’s induced lack of the AADC enzyme results in abnormally low levels of these neurotransmitters, chemical messengers that enable communication between nerve cells, affecting brain signaling and giving rise to disease symptoms.

Upstaza is designed to deliver a healthy copy of the DDC gene to nerve cells in the brain, allowing these cells to make a functional version of the AADC enzyme and, subsequently, the production of neurotransmitters.

The gene therapy is administered directly into the brain via a one-time surgical procedure done at a specialty clinic. It delivers its genetic payload using a modified version of a virus, adeno-associated virus serotype 2 (AAV2), that has been engineered to deliver the therapeutic gene rather than cause infection.

Upstaza has been approved in both the European Union and the U.K. since 2022. In both markets, it’s indicated to treat patients ages 18 months and older.

PTC applied for FDA approval of Upstaza in March, following a meeting with the agency late last year to discuss data needed to support an agency review. PTC’s application is based on findings in multiple clinical trials and compassionate use programs, showing that the gene therapy led to long-term reductions in symptom severity as well as improvements in motor function.

“The data collected to date continue to support the transformative benefit of Upstaza, this highly innovative gene therapy directly infused into the brain,” Klein said.