Doctors directly linked a pediatric patient's tumor to gene therapy treatment viruses in a rare documented safety case. A routine scan revealed a golf-ball sized tumor on Adam's brain in 2025 after he received gene therapy following a failed stem cell transplant at 13 months old. Encoded Therapeutics tested gene therapy for Dravet syndrome in 21 children, with some receiving sirolimus (rapamycin) as an immune suppressant alongside steroids.
Adam's tumor discovery
- ▪Adam was 13 months old when Adam's stem cell transplant failed
- ▪A routine scan revealed a golf-ball sized tumor on Adam's brain in 2025
- ▪Doctors warned that a second stem cell transplant for Adam carried a 10% to 15% risk of death
- ▪Adam's parents Mary Beth and Dave Brennan chose gene therapy over a second stem cell transplant after the first transplant failed
Immune suppression tradeoff
- ▪A key concern in gene therapy trials is that patients could mount an immune response against the engineered viruses used to deliver new genes into the brain
- ▪A medicine increasingly used to mitigate the risk of deadly gene therapy side effects could also blunt the therapy's effectiveness, according to a new study
- ▪Sirolimus is a drug historically given to prevent rejection in transplant recipients
- ▪Sirolimus is also known as rapamycin
Dravet syndrome trial
- ▪Adam was born with a life-threatening rare disease
- ▪Dravet syndrome is a severe form of genetic epilepsy
- ▪The Encoded Therapeutics Dravet syndrome trial included 21 children
- ▪Encoded Therapeutics assigned most of the 21 children in the Dravet syndrome trial to receive steroids, the most commonly used immune suppressant
- ▪A subset of patients in the Encoded Therapeutics Dravet syndrome trial, including most of the patients on the highest dose level, were assigned to also receive sirolimus
- ▪Encoded Therapeutics tested a gene therapy for Dravet syndrome in a trial
- ▪After receiving gene therapy, Adam reached milestones, learned sign language, and taught himself to read
Perspective of Gene therapy researchers and clinicians
- ▪A medicine increasingly used to mitigate the risk of deadly gene therapy side effects could also blunt the therapy's effectiveness, according to a new study
- ▪A key concern in gene therapy trials is that patients could mount an immune response against the engineered viruses used to deliver new genes into the brain
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