Reverta and RSRT Join Forces to Advance a Gene Therapy for Rett Syndrome

Reverta has begun a collaboration with the Rett Syndrome Research Trust (RSRT), and we are glad to share it. RSRT is putting $1.1 million behind the manufacturing of our gene therapy for Rett syndrome. For us it signals real belief in the program, and it moves us a step closer to the clinic.

Our program builds on Vania Broccoli's 2020 eLife study, the first to reach across the whole brain with an engineered viral capsid. That capsid worked only in mice, so our therapy is built instead for CapX, a newer capsid from Ben Deverman that binds the human transferrin receptor and outperforms the older vector. We reach it through a license RSRT holds with Apertura Gene Therapy.

Why our science is different

MECP2, the protein that people with Rett lack or cannot use, has to sit within a narrow range: too little causes Rett, too much causes MECP2 duplication syndrome. That range is not even the same in every cell, since neurons carry more than cells like astrocytes. So our therapy does two things at once. It holds expression down where it is not needed, sparing the healthy cells in girls who carry one working MECP2 copy, and it matches the amount each cell type is meant to have rather than pushing one flat dose across the brain.

A delivery system built for the brain

However good the cargo is, it counts for nothing if it cannot arrive, and getting a payload into every corner of the brain has stood among the field's stubbornest barriers for years.

This is the gap CapX closes. It is an engineered AAV capsid, licensed from Apertura Gene Therapy, that slips past the blood-brain barrier on the back of an ordinary intravenous infusion. The key is the human transferrin receptor. The capsid grabs that protein, which sits in abundance on the brain's blood vessels, and treats it as an entry point, spreading throughout the brain as it goes.

No one has dosed CapX in a person yet. Even so, its progress has the field paying close attention, and its first clinical use in other conditions is expected around the end of this year or the start of 2027. Put that delivery together with cargo engineered as carefully as ours, and you have a pairing that was out of reach even a couple of years ago. That is a large part of why this stage feels different to us.

What this partnership makes possible

Our work with RSRT opens on a stage of development that rarely draws the spotlight: manufacturing.

Good science on its own does not carry a therapy forward. Turning it into doses that come out consistent, in the volumes a trial demands, at the purity regulators insist on, is a heavy engineering job in its own right. It calls for the right people, the right facilities, and a careful, repeated cycle of tuning.

That is what RSRT's $1.1 million pays for, and the work happens at Viralgen, a manufacturer that has produced many AAV therapies. Batch by batch, we will scale up production of our CapX-plus-cassette therapy, sharpening the method as we go. We are after a process that behaves the same way on every run and yields material clean enough for the clinic, which is the bar a therapy has to clear before it can go into a person.

You will not see this stage written up in journals or announced in the press. Even so, until the therapy can be made dependably, nothing downstream follows: no trial groups, no data on whether it works, no striking results. And because most of what we learn transfers to any Rett effort that rides on CapX, the money does double duty, for the whole field and not only for us.

Right now the biology looks more encouraging than it ever has, and the delivery tools finally fit the problem they are meant to solve. Alongside RSRT, we are taking on the slow, unflashy work that gets a therapy out of the lab and to the children counting on it. We will share more as it moves along.