Key Takeaways
- PulseSight Therapeutics reported positive phase 1 results for PST-611, a first-in-class gene therapy for geographic atrophy, demonstrating excellent safety and tolerability
- Although the trial was primarily designed to assess safety, investigators observed encouraging early efficacy signals
- PulseSight plans to launch a repeat-dose phase 2a trial in up to 20 patients in H2 2026
PulseSight Therapeutics announced positive results from its phase 1 clinical trial evaluating PST-611 in patients with geographic atrophy (GA).
The findings from the first-in-human PST-611-CT1 study were presented in a podium session at the ARVO 2026 Annual Meeting.
According to PulseSight, PST-611 is a first-in-class gene therapy candidate designed to restore iron balance by encoding transferrin, a natural iron transporter critical to iron homeostasis. The PST-611-CT1 trial evaluated the safety and tolerability of two ascending dose levels of PST-611 in six patients across two sequential cohorts. Patients were monitored over a 16-week follow-up period.
The study was conducted in Paris and Grenoble under the leadership of Professor Francine Behar-Cohen, MD, PhD, at the Department of Ophthalmology, Cochin – Assistance Publique-Hôpitaux de Paris (AP-HP), and Professor Christophe Chiquet, MD, PhD, at the Department of Ophthalmology, CHU Grenoble Alpes.
According to the company, the trial met both its primary and secondary objectives, demonstrating an excellent safety and tolerability profile at both dose levels. Most ocular adverse events were mild, while two were classified as moderate. Investigators reported no intraocular inflammation, no treatment-emergent serious adverse events (SAEs), and no suspected unexpected serious adverse reactions (SUSARs). Best Corrected Visual Acuity (BCVA) remained stable throughout the study.
Although the study was not designed to evaluate efficacy, investigators observed early signals suggesting potential therapeutic benefit. These included spontaneous patient reports of vision improvement and anatomical indications of slowed GA lesion growth. In one patient, the observed efficacy signal reportedly persisted beyond the official study follow-up period.
“Geographic atrophy is a progressive, sight-threatening disease with no effective treatment currently available in Europe — the unmet medical need is real and urgent,” said Professor Behar-Cohen. “These Phase 1 results are therefore particularly meaningful. PST-611 demonstrated excellent tolerability, which is fundamental when treating patients with a chronic condition. What makes these results stand out are the early efficacy signals we observed, both anatomically and functionally.”
She added that the planned Phase 2a study would help determine the therapy’s potential in a larger patient population over a longer observation period.
PulseSight has submitted a Clinical Trial Authorization (CTA) application to the French regulatory authority, Agence Nationale de Sécurité du Médicament et des produits de santé (ANSM), for the upcoming PST-611-CT2 study. The Phase 2a trial is designed to evaluate the safety and explore the efficacy of three administrations of high-dose PST-611 over 52 weeks in up to 20 patients across three clinical sites. Pending regulatory approval, patient enrollment is expected to begin in the second half of 2026, with topline results anticipated in 2028.
