Avrobio has just announced that they will be stopping work on their investigative gene therapy for Fabry disease based on unexpected and disappointing results from a Phase 2 clinical trial. This trial demonstrated different results from previous investigations and has forced the company to reevaluate.

They will now stop recruiting patients for the trial and will officially be reprioritizing the research line. For the patients still enrolled in the trial (14 individuals), the company will continue to monitor outcomes.

Fabry Disease

Fabry disease is a rare lysosomal storage disorder. The body is not able to properly process sugar or fat. Current treatments include infusions of digestive proteins which Fabry disease patients don’t have.

Current research has focused on the genetic component of the disease, and how gene therapy may be able to improve outcomes for patients.

The Problem

The decision to stop the trial was based on data that showed 3 of the 5 recently dosed patients had declining levels of the protein the gene therapy was supposed to be producing. It appears the patients were resistant to the treatment.

The Phase 1 trial in Canada of 5 individuals demonstrated that the protein was increasing in the patients and they could even stop their standard therapy. For one individual, all toxins had been cleared. These results led to the initiation of the Phase 2 study.

But, the results of the new study were discordant with the past study. The stem cells didn’t take root in the body as well as they had before. In the first study, the engraftment was durable up to 54 months. In the second study, this was not the case. The researchers suspect “intrinsic resistance” for some Fabry disease patients to the engraftment.

Now What?

For now, Avrobio is shifting its focus to gene therapies for other rare diseases. Specifically, they will be focused on Gaucher disease and cystinosis. Research for both of these conditions is underway.

You can read more about this trial cancellation and what it means here.