Positive interim safety data were announced from a phase 1/2 clinical trial evaluating AT845 for the treatment of late-onset Pompe disease, as presented at the 18th Annual WorldSymposium 2022.

AT845 is an investigational adeno-associated virus-based gene replacement therapy by Astellas Gene Therapies. It aims to deliver a functional copy of the alpha-glucosidase (GAA) gene to the muscles of patients with late-onset Pompe disease. The gene is under a heart- and skeletal muscle-specific promotor.

The phase 1/2 trial is an ascending dose and multicenter study that aims to evaluate the safety and efficacy of AT845 in 8 patients with late-onset Pompe disease aged 18 years and older. It is currently recruiting participants in the US, Germany, and the UK.

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The primary endpoints of the trial are the frequency of adverse events, serious adverse events, and changes from baseline in relevant clinical laboratory tests, GAA protein expression, and enzymatic activity in muscle biopsies at week 12.

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As of the data cut-off date of December 3, 2021, the trial enrolled 4 participants. Two of these received 3 x 1013 vg per kg of treatment and the other 2 received 6 x 1013 vg per kg.

“In the two participants in Cohort 1 with follow-up duration through week 24 after dosing, AT845 demonstrated an encouraging safety profile,” Weston Miller, MD, senior medical director of Clinical Development at Astellas said in a press release. “Importantly, there have been no serious adverse events reported following dosing in any of the four participants as of the time of the data cut.”

Dr. Miler also reported that 1 participant had elevated transaminases, but this is considered a common immune-mediated treatment response, he said. “These safety data are encouraging, and the program continues to enroll participants.”


Astellas announces positive safety data from the FORTIS study of AT845 in adults with late-onset Pompe disease. News release. Astellas; February 7, 2022. 

Gene transfer study in patients with late onset Pompe disease (FORTIS). US National Library of Medicine. Updated August 27, 2021. Accessed February 16, 2022.