Biogen Plans to Initiate Phase 4 Study Evaluating Benefit of Spinraza in Patients Treated with Zolgensma

Biogen Inc., today announced, it plans to initiate a global Phase 4 clinical study, RESPOND, to examine the clinical benefit and assess the safety of SPINRAZA (nusinersen) in infants and children with spinal muscular atrophy (SMA) who still have unmet clinical needs following treatment with gene therapy Zolgensma (onasemnogene abeparvovec).

People with SMA do not produce enough survival motor neuron (SMN) protein, which is critical for the maintenance of motor neurons that support sitting, walking and basic functions of life, including breathing and swallowing. The RESPOND study will seek to understand if the proven efficacy of SPINRAZA and its continuous production of SMN protein may also benefit patients previously treated with gene therapy.

In a long-term study of Zolgensma, it has been reported that, to date, 4 out of 10 patients have been subsequently treated with SPINRAZA.Based on the planned study design, RESPOND will be a 2-year, open-label study to evaluate the efficacy and safety of SPINRAZA in SMA patients previously treated with Zolgensma to further inform treatment decisions. Efficacy will be assessed by change from baseline on motor function measures, additional clinical outcomes (e.g., swallowing), and caregiver burden. Neurofilament levels, an exploratory endpoint, will also be evaluated as a marker of biological disease activity. The primary study group aims to include 40 infants aged 9 months or younger (at the time of first SPINRAZA dose) who have 2 copies of SMN2 (likely to develop SMA Type 1) and received Zolgensma at 6 months old or younger. A second study group will include 20 children and will generate data in patients with a broader age range (up to 3 years old at the time of first SPINRAZA dose). After a screening period, participants will receive the approved 12mg dose of SPINRAZA, which is four loading doses followed by maintenance doses every four months, over the two-year study period.2

Biogen plans to submit the study protocol to the regulatory authorities in the coming months and aims for the first eligible patients to be enrolled in the RESPOND study in Q1 2021. The study is projected to enroll 60 children up to 3 years old who are determined by the investigator to have the potential for additional clinical improvement after receiving Zolgensma. Physicians will evaluate children for participation using criteria that may include one or more of the following: suboptimal motor function (e.g., a score lower than 50 on the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders [CHOP INTEND]); the need for respiratory support; abnormal swallowing or feeding ability; or other factors deemed relevant by the investigator.



  1. Zolgensma EU Summary of Product Characteristics (SmPC). Available at: Accessed on July 13, 2020.
  2. SPINRAZA U.S. Prescribing Information. Available at: Accessed on July 13, 2020.

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