ASEF BioX: The development of personalised gene therapy in seven months

At the last ASEF BioX Reading Circle event of the season, held on Wednesday 11 June 2025, ASEF Generation 2024 Fellow Lena Kogoj presented her paper, titled “Patient-Specific In Vivo Gene Editing to Treat a Rare Genetic Disease”.

This is a breakthrough success in the field of treating diseases with personalised gene therapies. In 2019, for the first time, CRISPR technology was used to treat and successfully cure a patient with sickle cell anaemia. This involved ex vivo therapy. Just 6 years later, for the first time in history, scientists were able to use in vivo gene editing to save the life of an infant with a rare genetic disease called carbamoyl phosphate synthase deficiency 1. In this disease, toxic ammonia, a by-product of protein metabolism, cannot be metabolised normally. The retention of ammonia in the body causes about 50% of patients to die as infants. Patients receive glycerol phenylbutyrate, which reduces the accumulation of ammonia, and can only eat extremely protein-restricted foods. In just seven months, scientists have developed a personalised treatment. During development, they prepared patient cell lines, tested different genome editors on them, and carried out toxicity studies in primate and mouse models. Key to this was the collaboration with the FDA, which approved this experimental treatment. The prepared drug was injected into the patient twice, at 7 and 8 months of age. The therapy successfully corrected mutations in the infant’s genome, allowing an increase in the protein content of the diet and a reduction in the dose of glycerol phenylbutyrate to lower blood ammonia levels.

Many more studies are needed in the future to examine more closely the two-hour safety of these therapies. Following the presentation, the Fellows also had an interesting debate on the research that led to this success, as well as the regulatory aspects and ethical dilemmas of gene therapies.