A phase 4 study is underway to assess the safety of nusinersen (Spinraza, Biogen) in infants and children with spinal muscular atrophy (SMA) who have unmet clinical needs following treatment with onasemnogene abeparvovec (Zolgensma).

The study, known as RESPOND, aims to evaluate the safety and efficacy of nusinersen in patients with suboptimal responses to onasemnogene abeparvovec. Individuals living with SMA do not produce enough survival motor neurons, which support sitting, walking, or basic functions of life such as breathing and swallowing.

RESPOND will be a 2-year, open-label study. Efficacy will be based on change from baseline on motor function measures, additional clinical outcomes such as swallowing, and caregiver burden, according to a press release. The first study group aims to include 40 infants aged 9 months or younger at the time of first nusinersen dose. The second group will include 20 children and will generate data in a broader age range of patients (up to 3 years old at the time of the first dose), according to the press release. Participants will receive a 12 mg dose of nusinersen, which is composed of 4 loading doses followed by a maintenance dose every 4 months over the 2-year study period. 

“Available data now show that some patients in the long-term study of Zolgensma have moved on to treatment with Spinraza. We believe that, for certain patients, motor neurons may be insufficiently treated by this gene therapy, and we plan to initiate this study to understand the extent to which Spinraza may potentially improve outcomes,” Chief Medical Officer at Biogen Maha Radhakrishnan, MD, said in the press release. 

More than 10,000 individuals have been treated with nusinersen as of March 31, 2020, according to the press release. SMA is the leading genetic cause of infant mortality, with 1 in 10,000 live births having an SMA diagnosis. 

Reference:
Biogen Plans to Initiate Phase 4 Study Evaluating Benefit of SPINRAZA® (nusinersen) in Patients Treated with Zolgensma® (onasemnogene abeparvovec) (News release), Cambridge, Mass. July 21, 2020, Globe Newswire, accessed July 22, 2020