Capsida Biotherapeutics Reports Death in Phase 1/2 Trial of CAP-002 for STXBP1 Developmental and Epileptic Encephalopathy
Capsida Biotherapeutics
Targeted Gene Therapy Developer
Recently, aClinical Patient Death Event Occurs with Rare Neurological Disease Gene Therapy Candidate.
Recently,Capsida Biotherapeutics Reports Its Gene Therapy CandidateIn the Phase 1/2 clinical trial of CAP-002, one patient died.
CAP-002 is aCandidate Gene Therapy for Rare Neurological Disorders, Indication under DevelopmentSTXBP1 Developmental Epileptic Encephalopathy (STXBP1-DEE). There is currently no disease-modifying therapy for STXBP1-DEE. Current treatments are limited to supportive care, including anti-seizure medications as well as physical, occupational, and speech therapy.
CAP-002 UtilizationCapsida's Proprietary Engineered Capsid(This engineered viral vector is able to penetrate the blood-brain barrier and avoid off-target effects in the liver.Dorsal Root Ganglion (DRG), Hepatotoxicity is a Prominent Safety Issue in AAV Gene Therapy; DRG Toxicity is Also Considered a Potential Safety Concern.Functional PortabilitySTXBP1 gene, to achieve stable supplementation in the brain after a single intravenous infusionSTXBP1 protein level.
InCapsida Biotherapeutics Inc. previously reported NHPIn GLP toxicology data,STXBP1 expression throughout the brain is dose-dependent, with off-target effects in the liver andDRG。NHP GLP Toxicology Results withPharmacological data from the STXBP1-DEE mouse model together indicate that all doses of CAP-002 are able toCorrect epileptic seizures, developmental disorders, and movement abnormalities.
In addition,Toxicology studies also showed that CAP-002 was well-tolerated, with no adverse clinical or histopathological findings in the entire central nervous system, DRG, or peripheral organs including the liver.
However, although the preclinical data was all good, a serious incident of patient death occurred just as it advanced into clinical trials.——May 2025,CAP-002 Receives FDA IND Clearance to Initiate Phase 1/2 Clinical Trial, Aiming to Enroll 12 ParticipantsSTXBP1-DEE Patients.
On September 10, 2025, Capsida Biotherapeutics Inc. reported the death of the first patient dosed in the Phase 1/2 clinical trial of CAP-002.
Currently, the company has not disclosed the details of the patient's death in this case.
Capsida Biotherapeutics Inc. has voluntarily paused the clinical trial of CAP-002 while determining the root cause of the patient's death. Capsida has alerted the FDA and will provide a full report to the FDA in accordance with regulations. Capsida has voluntarily paused the clinical trial of CAP-002 while determining the root cause of the patient's death and will evaluate subsequent steps pending the outcome of the ongoing review.
It is worth noting that, this isThe first human clinical trial initiated by Capsida Biotherapeutics Inc. In other words, the deceased patient was also the first to receiveThe proprietary engineered capsids of Capsida Biotherapeutics Inc. may have an adverse impact on subsequent clinical recruitment and development efforts, but this will depend on the outcome of the review.
In fact,The high difficulty of developing new drugs for the central nervous system (CNS) is an undeniable fact.
However, CNS diseases are one of the most recognized disease areas with the lowest contribution from drug treatments and the highest unmet clinical needs.
Based on social responsibility and potential market, major pharmaceutical companies have never ceased their research and development efforts for new CNS drugs, including several Aβ monoclonal antibodies launched in recent years. It is believed that with the efforts of the scientific community in the future, there will be more and better drugs emerging to benefit patients worldwide.
References:
1.https://capsida.com/a-letter-to-the-stxbp1-community/
2.https://capsida.com/capsida-presents-new-glp-toxicology-data-supporting-recent-fda-ind-clearance-of-its-first-in-class-iv-administered-gene-therapy-for-stxbp1-developmental-and-epileptic-encephalopathy/
3.https://capsida.com/pipeline/
