Solid Bio plummets on early DMD gene therapy readout

Solid Bio’s run of negative news is continuing with another setback for its Duchenne muscular dystrophy gene therapy.

Just a few months after the FDA relaxed a clinical hold it placed on the program due to safety and manufacturing concerns, the company has revealed that its SGT-001 candidate achieved low levels of expression of microdystrophin protein at the starting dose in a phase 1/2 trial.

Solid Bio says it is working toward escalating the dose used in the trial as soon as it can, but the early-stage miss didn’t go down well with investors and shares in the company were down more than two-thirds premarket.

The preliminary results come from biopsy data from the first three of six patients enrolled into the IGNITE DMD trial, and show that three months after SGT-001 was administered only one had detectable microdystrophin using western blot analysis but was “below the 5% level of quantification of the assay.”

The biotech’s co-founder and CEO Ilan Ganot said that despite the disappointing start that he is “confident we have the right approach in place to evaluate its potential at higher doses.” He also said Solid Bio’s scalable manufacturing process means it has “sufficient drug product available to dose escalate without delay.”

It’s possible of course that hiking the dose of SGT-001 will improve production, but the miss means that investors will have an anxious wait for data on higher doses due later in the year.

Moreover, the readout suffers in comparison to the impressive results in a phase 1/2 trial of a rival DMD gene therapy from Sarepta last year, which revealed production of microdystrophin at a level 38% of normal in the first three subjects enrolled, followed later on by improvements in muscle function.

DMD is a rare muscle-wasting disease that mostly affects boys and typically is fatal by age 30. It is caused by a defect in the gene coding for dystrophin, a protein found in muscles that is critical for movement.

Gene therapies like SGT-001, Sarepta’s AAVrh74.MHCK7.micro-dystrophin and Pfizer’s PF-06939926 are intended to produce a truncated version of the dystrophin protein to restore some functionality, in the hope of counteracting the progressive muscle injury that characterizes DMD. Studies have suggested that as little as 15% expression could be enough to have a clinical benefit.

Solid Bio insists it has the cash reserves needed to bring its program through the dose-escalation trials, but it risks falling behind in what is shaping up to be a competitive field.