Capsida has yet to disclose the exact cause of death. The patient had received the gene therapy CAP-002 for a type of epilepsy.
A patient has died after being treated with Capsida Biotherapeutics’ investigational gene therapy CAP-002, in development for STXBP1-related epileptic encephalopathy disorders.
In an announcement on Thursday, Capsida called the development “devastating.” The biotech doesn’t yet know the cause of the death and is “working with urgency to gather information and find answers.” Capsida will provide additional information regarding the mortality, and what its plans are for its CAP-002 program, after it has completed its assessment.
Following the patient death, Capsida said that it has voluntarily paused the study in question and has informed the FDA of the development.
“We wish to express our deepest condolences to the patient’s family and know that the entire community is grieving this loss,” the biotech wrote on Thursday.
In its own statement, the STXBP1 Foundation, a parent-led patient advocacy group, wrote that it is in “close contact” with Capsida and study investigators. The group likewise promised to “share verified updates as the formal safety review progresses.”
STXBP1 is a molecule that plays a role in cellular communication in the central nervous system. Dysfunctions in this protein can give rise to developmental and epileptic encephalopathy. Patients with this condition suffer from early-onset seizures, developmental delays and intellectual disabilities, and are at a heightened risk of sudden death. There are no disease-modifying treatments for STXBP1-driven conditions.
Administered intravenously, CAP-002 is a gene therapy that works by providing a stable supply of the STXBP1 protein throughout the brain. Capsida in its website claims that the asset has a “superior safety profile” versus other gene therapies because it doesn’t target “non-therapeutic organs.” The FDA has previously granted CAP-002 fast track and orphan drug designations.
Patient deaths have become an increasing concern this year. Most prominently, three mortalities have been tied to Sarepta Therapeutics’ gene therapies, including two linked to its Duchenne muscular dystrophy treatment Elevidys and a third associated with an investigational product for limb-girdle muscular dystrophy.
Three other companies also reported patient deaths last month. Allogene Therapeutics on Aug. 1 scrapped ALLO-647, a monoclonal antibody used for lymphodepletion, after it was implicated in a mortality in a Phase II study for the biotech’s CAR T therapy cemacabtagene ansegedleucel. A few days later, CytomX likewise reported a death in an early-stage study for an investigational antibody-drug conjugate being tested for colorectal cancer.
Also in early August, Agios Pharmaceuticals disclosed three deaths—all of which occurred in July—in patients who had been treated with its approved anemia drug Pyrukynd.
