Solid Biosciences has announced that the US Food and Drug Administration has put its phase 2/3 study of SGT-001, an experimental gene therapy for Duchenne muscular dystrophy, on clinical hold.
The FDA has halted the IGNITE DMD trial because of safety concerns, after a patient experienced a serious adverse event (SAE) which was deemed related to the drug. Following the news, shares in the biotech dropped up to 71%.
According to Solid Bio, to date six patients have been dosed with SGT-001 – this includes three patients in the first cohort at a 5E13 vg/kg dose who are well and continue to be followed per study protocol.
However, three patients were subsequently dosed in the second cohort at a 2E14vg/kg dose – the first two patients in this cohort are doing well with no report of SAE.
The third patient in this cohort experienced the SAE, which was characterised by complement activation, thrombocytopenia, a decrease in red blood cell count, acute kidney injury and cardio-pulmonary insufficiency.
Solid Bio has reported that the patient is being closely monitored by his care team and is recovering, and continuing to improve.
It reported the event to the FDA and the study’s Data Safety Monitoring Board (DSMB). The FDA then notified Solid Bio that the study had been placed on hold.
“We remain committed to bringing meaningful new therapies to the Duchenne community and continue to believe in the differentiated construct of SGT-001 and the potential benefits it may offer to patients,” said Ilan Ganot, Solid Bio’s CEO, president and co-founder.
“In the coming weeks, we anticipate that we will have a better understanding of the biological activity and potential benefit of SGT-001. We look forward to sharing this additional data and working with the FDA to resolve the clinical hold and determining next steps for the programme.”
This is not the first time a DMD gene therapy candidate has been set back by safety fears – in August, the FDA rejected Sarepta Therapeutics’ DMD drug Vyondys 53.
The complete response letter raised concerns about a risk of infections related to the intravenous infusion port used to administer the therapy. It also highlighted worries about kidney toxicity seen in preclinical studies.
In the meantime, rival candidate viltolarsen from Japanese pharma Nippon Shinyaku (NS Pharma) has been filed with the FDA for the treatment of DMD. Although the FDA has not yet set an approval decision date, if there are no significant issues viltolarsen could enter the market by mid-2020.
For Solid Bio, the wait will be longer – there is not indication as to when, and if, the trial will re-commence.
For the time being, the company will work with the regulatory authority to determine next steps, and has also planned to report additional biomarker data from the study before the end of the year.