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Published: 29 June 2023
Cormac Sheridan1
Nature Biotechnology
(2023)Cite this article
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Biogen’s drug Qalsody is the first drug to gain approval for a genetically defined form of ALS, but there is more to come as developers zoom in on a wide range of disease targets.
Qalsody, which Biogen licensed from Ionis Pharmaceuticals, is the fourth ALS drug to gain approval, after Rilutek (riluzole), Radicava (edaravone) and Relyvrio (sodium phenylbutyrate and taurursodiol), all of which have modest effects on disease progression. The mechanisms underpinning these other drugs are not as precisely characterized at a molecular level as that of Qalsody: the drug reduces a mutated form of superoxide dismutase 1 (SOD1), an enzyme that prevents oxidative damage. When mutated, the presence of toxic protein aggregates and the enzyme’s loss of function may both contribute to the disease pathology. The case for Qalsody’s approval relies on numerous independent studies demonstrating that high levels of NfL are associated with fast disease progression and early death. NfL is a cylindrical neurofilament present abundantly in the cytoplasm of neurons. Any form of neuronal damage results in NfL release into the cerebrospinal fluid and the plasma, which can be readily measured by an immunoassay. NfL is not diagnostic of ALS — it is a non-specific marker of neuronal damage and is elevated in a range of other neurodegenerative diseases as well as ALS. In Biogen’s 28-week pivotal study, those on the drug had an average 55% reduction from baseline NfL concentrations, whereas those on placebo experienced an average 12% increase. The FDA concluded that these effects “are reasonably likely” to predict a clinical benefit in patients. Todd Carter, CSO at Voyager Therapeutics, concurs. “I think that may be one of the first signs that you’re having an effect,” he says.
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Author informationAuthors and AffiliationsDublin, Ireland
Cormac Sheridan
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Cite this articleSheridan, C. Unprecedented blood biomarker enables ALS drug approval.
Nat Biotechnol (2023). https://doi.org/10.1038/s41587-023-01862-0
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Published: 29 June 2023
DOI: https://doi.org/10.1038/s41587-023-01862-0
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