July 08, 2026 —
Genespire, in collaboration with researchers at the San Raffaele Telethon Institute for Gene Therapy, announced the publication of preclinical data supporting its liver-directed immune-shielded lentiviral vector gene therapy approach for methylmalonic acidemia, or MMA.
The findings, published in the Journal of Hepatology, showed that a single systemic administration of a lentiviral vector encoding the MMUT gene produced durable therapeutic benefits in a validated mouse model of MMA. The effects lasted for the average lifespan of laboratory mice, supporting the potential durability of the approach through postnatal growth and liver maturation.
MMA is a rare inherited metabolic disorder most commonly caused by mutations in the gene encoding methylmalonyl-CoA mutase, or MUT, a mitochondrial enzyme required for the metabolism of certain proteins and fats. When the enzyme is deficient, methylmalonic acid and other toxic metabolites accumulate, leading to recurrent metabolic crises, growth failure, neurological impairment, and damage to the liver, kidneys, brain, and other organs.
Genespire’s platform uses immune-shielded lentiviral vectors, or ISLVs, designed for intravenous administration and long-term production of therapeutic proteins from the patient’s liver. The approach is intended to provide an off-the-shelf, single-administration therapy for pediatric genetic diseases, particularly inherited metabolic disorders with high unmet need.
In the published study, researchers also evaluated a vector containing an optimized MMUT transgene, which improved therapeutic efficacy. In the same MMA mouse model, this optimized version produced dose-dependent improvements in metabolomic biomarkers, with gene transfer efficiency exceeding 80% of the liver.
The study further suggested that genetically corrected liver cells may gradually replace diseased cells over time. This finding indicates that therapeutic benefit could progressively improve, even when starting from lower initial treatment doses.
Genespire said the data support continued advancement of GENE202, its lead MMA program, toward clinical development. The company believes the results contribute to a broader preclinical package supporting the potential initiation of clinical testing in pediatric patients with MMA.
The work also reflects the continued translation of lentiviral gene therapy technologies from ex vivo applications into systemic in vivo delivery. If successfully advanced into human studies, Genespire’s ISLV platform could offer a differentiated liver-directed strategy for metabolic diseases requiring durable therapeutic protein expression.
While the findings remain preclinical, the durability, liver transduction efficiency, and biomarker improvements reported in the study provide a rationale for further development of GENE202 as a potential disease-targeted therapy for MMA, a condition for which no approved disease-modifying drugs are currently available.
