Complement Therapeutics Doses First Patient in Phase I/II Trial for Geographic Atrophy

CTx001 gene therapy aims to treat vision loss from age-related macular degeneration

Mar. 25, 2026 at 10:21am

Got story updates? Submit your updates here. ›

Complement Therapeutics, a clinical-stage biotech company, has dosed the first patient in its Opti-GAIN Phase I/II clinical trial evaluating the safety, tolerability and preliminary efficacy of its investigational gene therapy CTx001 for the treatment of Geographic Atrophy (GA) secondary to Age-related Macular Degeneration (AMD). CTx001 is designed to deliver mini-CR1, a potent modulator of the complement system, to retinal cells via a single subretinal injection.

Why it matters

Geographic Atrophy is a leading cause of vision loss with no approved treatments, so new therapeutic approaches like CTx001 are critical to address this significant unmet medical need. The Opti-GAIN study is being conducted alongside Complement's Pre-GAIN natural history study, which aims to provide insights to support the development of novel endpoints to assess the treatment effect of CTx001.

The details

Opti-GAIN is a multi-center Phase I/II study that will evaluate CTx001 across three dose cohorts in an open-label, dose-escalation design, followed by a dose-expansion phase. The study is being led by Dr. Arshad M. Khanani, Director of Clinical Research at Sierra Eye Associates in Reno, Nevada. CTx001 is an AAV2-based gene therapy designed to deliver mini-CR1, a truncated form of Complement Receptor 1 that can modulate both the alternative and classical complement pathways. The subretinal delivery of CTx001 aims to enable local retinal production of mini-CR1 and broad ocular biodistribution.

  • The first patient was dosed in the Opti-GAIN study on March 25, 2026.

The players

Complement Therapeutics GmbH

A clinical-stage biotechnology company developing next-generation therapeutics for complement-mediated diseases.

Dr. Arshad M. Khanani

The trial's Chief Investigator and Director of Clinical Research at Sierra Eye Associates in Reno, Nevada.

CTx001

An investigational AAV2-based gene therapy designed to deliver mini-CR1, a potent modulator of multiple pathways of the complement system, to retinal cells.

Got photos? Submit your photos here. ›

What they’re saying

“Geographic Atrophy remains an area of significant unmet need, and there is a clear need to evaluate novel approaches for patients facing progressive vision loss.”

— Dr. Arshad M. Khanani, Chief Investigator, Opti-GAIN study; Director of Clinical Research, Sierra Eye Associates

“Dosing the first patient in Opti-GAIN is an important milestone for Complement Therapeutics and for the advancement of CTx001 in Geographic Atrophy.”

— Dr. Rafiq Hasan, Chief Executive Officer, Complement Therapeutics

What’s next

Complement Therapeutics plans to advance the Opti-GAIN study through the dose-escalation and dose-expansion phases to further evaluate the safety, tolerability and preliminary efficacy of CTx001 in patients with Geographic Atrophy secondary to AMD.

The takeaway

The initiation of the Opti-GAIN study represents an important step forward in the development of novel gene therapy approaches to treat Geographic Atrophy, a leading cause of vision loss with no approved treatments currently available.