Lysogen: The partial failure of a research on Sanfilippo syndrome weighs on the value of Lysogen

(BFM Bourse) – Lysosomal disease specialist Lysogene falls from the Paris Bourse after failing the primary and secondary criteria of the main cohort of its Phase II/III study of LYS-SAF302. However, the study in the younger patient cohort met its primary and secondary endpoints.

Lysogene, a gene therapy company, on Friday evening announced key results from the Phase II/III AAVance study evaluating LYS-SAF302, its investigational treatment for mucopolysaccharidosis type IIIA (MPS IIIA), also known as the Sanfilippo syndrome.

partial results

As the company states in a press release, the study failed to meet the primary efficacy endpoint in the main cohort (12 patients recruited more than 30 months of age). The aim was to assess the reduction in decline in cognitive development quotient (DQ) 24 months after treatment compared to the natural history data of this disease.

Lysogen’s stock fell Monday in response to this clinical failure in the cohort of patients recruited 30 months of age and older. At around 2:10 p.m., the action fell 25% to $0.57 after rising almost 60% on Friday. Investors expected better results for lysogens.

This 30-month cohort also failed to meet key secondary efficacy endpoints, including the percentage of patients with stabilization or improvement in cognitive AD (developmental age), AD-related language and motor function at 24 months compared to baseline, and changes in VABS-II scores [ test qui mesure les compétences adaptatives (communication, autonomie de la vie quotidienne, socialisation et motricité, NDLR] compared to natural history data.

MPS IIIA affects approximately 1 in 100,000 newborns and is a disease characterized by behavioral problems and severe intellectual regression, most commonly fatal in patients between the ages of 15 and 20. It’s caused by mutations in a gene that makes an enzyme needed to recycle a compound called heparan sulfate (HS) in cells. If this cleansing is not allowed, the HS becomes overloaded, which triggers pronounced neurodegeneration. In the absence of any therapeutic option, Lysogene is developing LYS-SAF302, a gene therapy to be injected into the brain to deliver a functional copy of the defective gene thanks to a single administration.

“Although we are disappointed with the results obtained in the main cohort of patients recruited at the age of 30 months or older, these can probably be explained by the rapid progression of the disease and by recent lessons from other clinical trials that Diseases that involve gene therapy treatment for neurodegenerative diseases should be initiated as early as possible to achieve therapeutic benefit, before irreversible neuronal damage occurs,” said Karen Aiach, Founder of Lysogene.

Hope in subjects under 30 months

In contrast, in subjects recruited less than 30 months of age, Lysogene observed a statistically significant improvement in cognitive development 24 months after treatment compared to natural history. Subjects in this cohort also met key secondary efficacy endpoints. Statistical analysis confirms previously reported qualitative observations in the younger patient population with consistent impact on endpoints. Lysogene therefore believes that the results of the AAVance study make it possible to define the patient population that could benefit from treatment with LYS-SAF302

“The positive efficacy signals observed in very young subjects recruited before the age of 30 months indicate that early administration of LYS-SAF302 gene therapy in children with MPS IIIA can have a truly beneficial effect on these patients and could change her life,” he adds Karen Ach. .

Fruitful talks with the EMA

The Company reports that it entered fruitful discussions with regulatory authorities in the European Union late in the third quarter and plans to expand these discussions to all relevant regulatory authorities to find a way to rapidly advance LYS-SAF302 clinical development in the population younger patients with MPS IIIA.

To advance the development of LYS-SAF302 in accordance with regulatory requirements, Lysogene claims to have sufficient cash resources, with current availability bringing financial visibility through February 2023. “Strategic discussions are ongoing, prioritizing a non-dilution solution in the form of a licensing collaboration for one or more of its programs,” the company also said.

In the meantime, the company is sticking to its cost control initiatives launched earlier this year, which now ensure a liquidity horizon until February 2023. Lysogene will release updated data and key results from this Phase II/III AAVance gene therapy clinical trial on Wednesday, November 23rd.

Sabrina Sadgui – ©2022 BFM Stock Exchange

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