for people ages 18-80 (full criteria)
at Orange, California and other locations
study started
estimated completion
Principal Investigator
by Tahseen Mozaffar, MD
Headshot of Tahseen Mozaffar
Tahseen Mozaffar



This is a phase 1/2 open-label, ascending dose, multicenter clinical study to evaluate the safety and efficacy of AT845 in adult (aged ≥ 18 years) subjects, ambulatory or nonambulatory, with Late Onset Pompe Disease (LOPD).

Official Title

A Phase 1/2, Open-Label, Ascending-Dose Clinical Study to Evaluate the Safety and Preliminary Efficacy of AT845, an AAV8-Delivered Gene Transfer Therapy in Patients With Late Onset Pompe Disease


This study (FORTIS) will evaluate the safety and efficacy of an investigational gene replacement therapy, AT845, in adult subjects with LOPD. Subjects will receive a single dose of AT845 delivered via intravenous (IV) infusion.

Up to 3 nominal dose levels of AT845 are planned to be evaluated in this study. A single AT845 administration via IV infusion is planned for each subject. The initial dosing cohort received a single dose of 3x1013 vg/kg of AT845. The second dose cohort will receive a single dose of 6×1013 vg/kg. The third dose cohort will receive a single dose of 1×1014 vg/kg. Dose escalation between cohorts will be based on evaluations of safety and in consultation with the independent DMC.

There will be a core observation period of 48 weeks with scheduled visits and assessments. Following the conclusion of the core observation period, subjects will be seen every 6 months for a safety follow-up visit for up to 5 years postdose.


Pompe Disease (Late-onset), LOPD, Glycogen Storage Disease Type II


You can join if…

Open to people ages 18-80

  • Subject is aged ≥ 18 years (ambulatory or nonambulatory).
  • Subject has a documented clinical diagnosis of Pompe disease by genetic testing.
  • Subject has received enzyme replacement therapy (ERT) with rhGAA for the previous ≥ 2 years.
  • Subject has been on a stable standard dose (at least 20 mg/kg every 2 weeks) of ERT with rhGAA for at least the previous 6 months.
  • Subject has upright FVC ≥ 30% of predicted normal value.
  • Subject or legally authorized representative(s) (LAR) (if applicable) provides written informed consent.
  • Subject must agree to use appropriate contraception following consent through 6 months post AT845 administration.

You CAN'T join if...

  • Subject is currently participating in an interventional study or has received gene or cell therapy.
  • Subject tests positive for AAV8 neutralizing antibodies with titers above protocol specified threshold.
  • Subject has received immune-modulating agents within 90 days before dosing (use of inhaled corticosteroids is allowed).
  • Subject tests positive for GAA total antibodies with titers above protocol specified threshold.
  • Subject has a high risk for a severe allergic reaction to rhGAA (ie, previous moderate to severe anaphylactic reaction to alglucosidase alfa or and/or a history of sustained high immunoglobulin G [IgG] antibody titers to alglucosidase alfa that in the opinion of the Investigator suggests a high risk for an allergic reaction to ERT).
  • Subject has an active viral infection based on clinical observation.
  • Subject has a history of, or currently has, a clinically important cardiac condition, such as an echocardiogram (ECHO) with ejection fraction below 40%, or has symptoms or signs of cardiomyopathy that in the opinion of the Investigator precludes enrollment.
  • Subject has a clinically significant underlying liver disease.
  • Subject has a contraindication to study drug or ingredients or to corticosteroids.


  • University of California Irvine, Department of Neurology accepting new patients
    Orange California 92868 United States
  • Stanford University accepting new patients
    Palo Alto California 94304 United States

Lead Scientist at UC Irvine

  • Tahseen Mozaffar, MD
    Clinical Professor, Neurology, School of Medicine. Authored (or co-authored) 134 research publications


accepting new patients
Start Date
Completion Date
Astellas Gene Therapies
Phase 1/2 Pompe Disease Research Study
Study Type
Expecting 12 study participants
Last Updated