Risdiplam-Treated Infants with Type 1 Spinal Muscular Atrophy versus Historical Controls.

Basil T Darras Riccardo Masson Maria Mazurkiewicz-Bełdzińska Kristy Rose Hui Xiong Edmar Zanoteli Giovanni Baranello Claudio Bruno Dmitry Vlodavets Yi Wang Muna El-Khairi Marianne Gerber Ksenija Gorni Omar Khwaja Heidemarie Kletzl Renata S Scalco Paulo Fontoura Laurent Servais

N Engl J Med

From the Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston (B.T.D.); the Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan (R.M., G.B.), and the Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa (C.B.) - both in Italy; the Department of Developmental Neurology, Medical University of Gdańsk, Gdańsk, Poland (M.M.-B.); the Paediatric Gait Analysis Service of New South Wales, the Children's Hospital at Westmead and the University of Sydney, Sydney (K.R.); the Department of Pediatrics, Peking University First Hospital, Beijing (H.X.), and Children's Hospital of Fudan University, Shanghai (Y.W.) - both in China; the Department of Neurology, Faculdade de Medicina, Universidade de São Paulo, São Paulo (E.Z.); the Dubowitz Neuromuscular Centre, National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre, University College London Great Ormond Street Institute of Child Health, and Great Ormond Street Hospital for Children NHS Foundation Trust, London (G.B.), Roche Products, Welwyn Garden City (M.E.-K.), and the Muscular Dystrophy UK Oxford Neuromuscular Centre, the Department of Paediatrics, University of Oxford, Oxford (L.S.) - all in the United Kingdom; Russian Children Neuromuscular Center, Veltischev Clinical Pediatric Research Institute, Pirogov Russian National Research Medical University, Moscow (D.V.); Pharma Development, Safety (M.G.), Product Development Medical Affairs - Neuroscience and Rare Disease (K.G., P.F.), and Pharma Development Neurology (R.S.S.), F. Hoffmann-La Roche, and Roche Pharmaceutical Research and Early Development, Roche Innovation Center Basel (O.K., H.K.) - both in Basel, Switzerland; the Division of Child Neurology, Centre de Références des Maladies Neuromusculaires, the Department of Pediatrics, University Hospital Liege, University of Liege, Liege, Belgium (L.S.); and I-Motion, Institut de Myologie, Assistance Publique Hôpitaux de Paris, Hôpital Armand Trousseau, Paris (L.S.).

Published: July 2021

Type 1 spinal muscular atrophy (SMA) is a severe neuromuscular condition that affects infants, characterized by an inability to sit unsupported and low levels of survival of motor neuron (SMN) protein.
The study tested risdiplam, a medication that enhances SMN protein levels, in infants aged 1 to 7 months and evaluated its effectiveness and safety over 12 months compared to historical controls.
Results showed that 29% of infants could sit without support after treatment and significant improvements were seen in key motor function assessments versus historical data.

Background: Type 1 spinal muscular atrophy (SMA) is a progressive neuromuscular disease characterized by an onset at 6 months of age or younger, an inability to sit without support, and deficient levels of survival of motor neuron (SMN) protein. Risdiplam is an orally administered small molecule that modifies pre-messenger RNA splicing and increases levels of functional SMN protein in blood.

Methods: We conducted an open-label study of risdiplam in infants with type 1 SMA who were 1 to 7 months of age at enrollment. Part 1 of the study (published previously) determined the dose to be used in part 2 (reported here), which assessed the efficacy and safety of daily risdiplam as compared with no treatment in historical controls. The primary end point was the ability to sit without support for at least 5 seconds after 12 months of treatment. Key secondary end points were a score of 40 or higher on the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND; range, 0 to 64, with higher scores indicating better motor function), an increase of at least 4 points from baseline in the CHOP-INTEND score, a motor-milestone response as measured by Section 2 of the Hammersmith Infant Neurological Examination (HINE-2), and survival without permanent ventilation. For the secondary end points, comparisons were made with the upper boundary of 90% confidence intervals for natural-history data from 40 infants with type 1 SMA.

Results: A total of 41 infants were enrolled. After 12 months of treatment, 12 infants (29%) were able to sit without support for at least 5 seconds, a milestone not attained in this disorder. The percentages of infants in whom the key secondary end points were met as compared with the upper boundary of confidence intervals from historical controls were 56% as compared with 17% for a CHOP-INTEND score of 40 or higher, 90% as compared with 17% for an increase of at least 4 points from baseline in the CHOP-INTEND score, 78% as compared with 12% for a HINE-2 motor-milestone response, and 85% as compared with 42% for survival without permanent ventilation (P<0.001 for all comparisons). The most common serious adverse events were pneumonia, bronchiolitis, hypotonia, and respiratory failure.

Conclusions: In this study involving infants with type 1 SMA, risdiplam resulted in higher percentages of infants who met motor milestones and who showed improvements in motor function than the percentages observed in historical cohorts. Longer and larger trials are required to determine the long-term safety and efficacy of risdiplam in infants with type 1 SMA. (Funded by F. Hoffmann-La Roche; FIREFISH ClinicalTrials.gov number, NCT02913482.).

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http://dx.doi.org/10.1056/NEJMoa2102047	DOI Listing

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