Capsida Biotherapeutics said it still cannot determine the cause behind a child’s death in its CAP-002 gene therapy trial, citing continued obstacles in accessing autopsy tissue samples. The company said its investigation efforts have been stymied because the hospital where the study took place declined to share tissues. CAP-002 is described as a first-in-class effort in the wave of gene therapies designed to deliver genes deep into the brain, targeting diseases where crossing the blood-brain barrier is a central challenge. The update matters for gene therapy operators and regulators because it emphasizes how data access constraints can slow causal analysis after serious safety events, affecting timelines for follow-up studies and potential program adjustments.