Orchard Therapeutics announced the U.S. Food and Drug Administration (FDA) has approved Lenmeldy? (atidarsagene autotemcel), formerly known as OTL-200, for the treatment of children with pre-symptomatic late infantile (PSLI), pre-symptomatic early juvenile (PSEJ) or early symptomatic early juvenile (ESEJ)?collectively referred to as early-onset?metachromatic leukodystrophy (MLD). MLD is a rare, fatal genetic disorder caused by a mutation in the gene responsible for encoding the enzyme arylsulfatase A (ARSA) leading to neurological damage and developmental regression due to the accumulation of fats called sulfatides in the brain and other areas of the body which, when not broken down, damage the central nervous system over time.

In its most severe form, babies develop normally but in late infancy start to rapidly lose the ability to walk, talk and interact with the world around them. These children eventually deteriorate into a vegetative state, which may require 24-hour intensive care, and the majority pass away within five years of disease onset, creating an enormous emotional and financial burden on the family. Lenmeldy aims to correct the underlying genetic cause of MLD by inserting one or more functional copies of the human ARSA gene ex vivo (outside the body) into the genome of a patient?s own hematopoietic stem cells (HSCs) using a lentiviral vector.

The genetically repaired cells are infused back into the patient, where, once engrafted, they differentiate into multiple cell types, some of which migrate across the blood-brain barrier into the central nervous system and express the functional enzyme. This approach has the potential to restore enzymatic function to stop or slow disease progression with a single treatment. Lenmeldy was granted Priority Review in September 2023.

It was previously given both Rare Pediatric Disease (RPD) and Regenerative Medicine Advanced Therapy (RMAT) designations from FDA. In connection with the approval, Orchard Therapeutics received a Priority Review Voucher (PRV), which will be transferred to GSK in accordance with the terms of the original licensing agreement. The FDA approval of Lenmeldy is based on data from 37 pediatric patients with early-onset MLD, enrolled in two single-arm, open-label clinical studies or treated under European expanded access frameworks, who received a one-time administration of the gene therapy and compared with natural history data.

All treated patients were administered Lenmeldy and subsequently monitored at Ospedale San Raffaele in Milan, Italy. With more than 12 years of follow-up in the earliest treated patients (median 6.76 years), treatment with Lenmeldy significantly extended overall survival and resulted in the preservation of motor function and cognitive skills in most late infantile MLD patients past ages at which untreated patients showed severe cognitive and motor impairments. Lenmeldy also resulted in the preservation of motor function and cognitive skills in some early juvenile MLD patients which is not expected when compared to untreated patients.

The most common non-laboratory adverse reactions (incidence = 10%) were: febrile neutropenia (85%), stomatitis (77%), respiratory tract infections (54%), rash (33%), device related infections (31%), other viral infections (28%), pyrexia (21%), gastroenteritis (21%), and hepatomegaly (18%). The most common laboratory abnormalities were: elevated D-dimer (67%), neutropenia (28%), and elevated liver enzymes (23%). Please see below for additional details and Important Safety Information.

MLD is a rare and life-threatening inherited disease of the body?s metabolic system estimated to occur in approximately one in every 100,000 live births based on existing literature. MLD is caused by a mutation in the arylsulfatase-A (ARSA) gene that results in the accumulation of sulfatides in the brain and other areas of the body, including the liver, gallbladder, kidneys, and/or spleen. Over time, the nervous system is damaged, leading to neurological problems such as motor, behavioral and cognitive regression, severe spasticity and seizures.

Patients with MLD gradually lose the ability to move, talk, swallow, eat and see. In its late infantile form, mortality at five years from onset is estimated at 50% and 44% at 10 years for juvenile patients. Lenmeldy?

(atidarsagene autotemcel), formerly known as OTL-200, is the only approved therapy in the U.S. for the treatment of children with pre-symptomatic late infantile (PSLI), pre-symptomatic early juvenile (PSEJ) or early-symptomatic early juvenile (ESEJ) metachromatic leukodystrophy (MLD).