Atidarsagene autotemcel, sold under the brand name Libmeldy among others, is a gene therapy treatment for metachromatic leukodystrophy developed by Orchard Therapeutics. It contains an autologous CD34⁺ cell enriched population that contains haematopoietic stem and progenitor cells transduced using a lentiviral vector encoding the human arylsulfatase A (ARSA) gene.^[6]

The most common side effects include fever and low white blood cell count, mouth sores, respiratory infections, rash, medical line infections, viral infections, fever, gastrointestinal infections and enlarged liver.^[7]

Atidarsagene autotemcel was approved for medical use in the European Union in December 2020,^[4][8] in the United Kingdom in February 2021,^[1] and in the United States in March 2024.^[7] Is it is the first gene therapy approved by the US Food and Drug Administration (FDA) for the treatment of metachromatic leukodystrophy.^[7]

Medical uses

Atidarsagene autotemcel is indicated for the treatment of metachromatic leukodystrophy characterized by biallelic mutations in the arysulfatase A (ARSA) gene leading to a reduction of the ARSA enzymatic activity in children with late infantile or early juvenile forms, without clinical manifestations of the disease; and in children with the early juvenile form, with early clinical manifestations of the disease, who still have the ability to walk independently and before the onset of cognitive decline.^[1][4][9]

In the US, atidarsagene autotemcel is indicated for the treatment of children with pre-symptomatic late infantile, pre-symptomatic early juvenile or early symptomatic early juvenile metachromatic leukodystrophy.^[7]

Atidarsagene autotemcel is a one-time, individualized single-dose infusion made from the recipient's own hematopoietic (blood) stem cells, which have been genetically modified to include functional copies of the ARSA gene.^[7] The stem cells are collected from the recipient and modified by adding a functional copy of the ARSA gene.^[7] The modified stem cells are transplanted back into the recipient where they engraft (attach and multiply) within the bone marrow.^[7] The modified stem cells supply the body with myeloid (immune) cells that produce the ARSA enzyme, which helps break down the harmful build-up of sulfatides and may stop the progression of MLD.^[7] Prior to treatment, recipients must undergo high-dose chemotherapy, a process that removes cells from the bone marrow so they can be replaced with the modified cells in atidarsagene autotemcel.^[7]

History

The FDA assessed the safety and effectiveness of atidarsagene autotemcel based on data from 37 children who received atidarsagene autotemcel in two single-arm, open-label clinical trials and in an expanded access program.^[7] Children who received treatment with atidarsagene autotemcel were compared to untreated children (natural history).^[7] The primary efficacy endpoint was severe motor impairment-free survival, defined as the interval from birth to the first occurrence of loss of locomotion and loss of sitting without support or death.^[7] In children with metachromatic leukodystrophy, treatment with atidarsagene autotemcel significantly reduced the risk of severe motor impairment or death compared with untreated children.^[7] All children with pre-symptomatic late infantile metachromatic leukodystrophy who were treated with atidarsagene autotemcel were alive at six years of age, compared to only 58% of children in the natural history group.^[7] At five years of age, 71% of treated children were able to walk without assistance.^[7] 85% of the children treated had normal language and performance IQ scores, which has not been reported in untreated children.^[7] In addition, children with pre-symptomatic early juvenile and early symptomatic early juvenile metachromatic leukodystrophy showed slowing of motor and/or cognitive disease.^[7]

The FDA granted the application for atidarsagene autotemcel priority review, orphan drug, rare pediatric disease, and regenerative medicine advanced therapy designations.^[7] The FDA granted approval of Lenmeldy to Orchard Therapeutics.^[7]

Society and culture

Legal status

Atidarsagene autotemcel was approved for medical use in the EU in December 2020,^[6][4] in the UK in February 2021,^[1] and the US in March 2024.^[7][10]

Economics

In February 2022, it was announced that NHS England would be providing the drug to metachromatic leukodystrophy patients, after negotiating a discount with the manufacturer.^[11][12] The assessment by BeneluxA concluded that it should only be reimbursed if the company offered a significant price reduction.^[13] The National Centre for Pharmacoeconomics (NCPE) in Ireland recommends "that atidarsagene autotemcel not be considered for reimbursement unless cost effectiveness can be improved relative to existing treatment."^[9]