Treating adults with spinal muscular atrophy (SMA) with Spinraza (nusinersen) was safe and improved their muscle strength, and motor and respiratory function, among other benefits, according to preliminary research.
Three studies presented at the 2019 American Academy of Neurology (AAN) Annual Meeting, recently held in Philadelphia, were designed to address this gap.
In one study, “Outcome measures for Nusinersen efficacy in Adults with Spinal Muscular Atrophy,” eight SMA type 3 patients between the ages of 25 and 56 were treated with Spinraza for an average of seven months (range: 2-13 months). During that time, all patients reported feeling more energized and having greater exercise tolerance.
The data also showed that the three patients who were unable to walk all experienced improvements in cognitive function and sleep, as well as less fatigue, as assessed with the Pediatric Quality of Life Inventory (PedsQL). In contrast, among those able to walk, none had improvements in cognitive function, and half experienced better sleep.
Treatment with Spinraza also was associated with improved motor function, as measured by the Revised Upper Limb Measure (RULM) and the Hammersmith Functional Motor Score-Expanded, and with improved pulmonary function over a mean of 8.5 months. No changes were found in the 6-minute walk test (6MWT) of exercise tolerance, or the SMA-Functional Rating Scale of overall function.
In the second study, “Prospective open-label study of Nusinersen treatment for adults with Spinal Muscular Atrophy,” researchers primarily evaluated muscle and pulmonary function changes at 14 months of treatment with Spinraza in 32 patients with 5q SMA (17 women; mean age 39 years, range 18-65).
Exercise tolerance, motor function, lean mass, and the ulnar muscle’s response to nerve fiber stimulation — called compound muscle action potential, or CMAP — and number of motor units (MUNE) also were analyzed. The ulnar muscle’s main function is to move the wrist and fingers.
A total 185 intrathecal (spinal canal) injections of Spinraza were delivered to the 32 study participants, with 12 receiving the therapy into the cervical spinal cord guided by a medical imaging called fluoroscopy.
Comorbidities, or the patients’ other chronic diseases, included anxiety, depression, renal insufficiency, hypertension, and diabetes mellitus. At the study’s start, the participants — particularly those severely affected — showed limitations in common SMA outcome measures assessing motor function and muscle strength.
Following treatment, the researchers found stability in measures of motor function, with those able to walk performing better than those who could not walk. The early findings also showed a trend towards better CMAP scores and stable MUNE results, which suggests improved nerve supply, the researchers said.
Safety results revealed that Spinraza was well-tolerated. Among observed adverse events, headaches were mostly mild and transient, and no case of post-lumbar puncture syndrome — a common complication of lumbar puncture — required a blood patch. Back pain and pulmonary infections also were noted.
The third study, “Nusinersen Efficacy in Adults with Spinal Muscular Atrophy,” used data from 99 untreated adult SMA patients in the Pediatric Neuromuscular Clinical Research (PNCR) Network‘s database as a baseline, or starting point, for the natural history of SMA. Researchers then compared disease progression in 34 participants being treated with Spinraza to that baseline.
More than 90% of those treated reported improvements in muscle, vocal, and breathing strength, as well as in stamina, chewing and swallowing, and in jaw range of motion. Treated patients also showed improvements in the RULM and 6MWT measures of motor function, in the CHOP-Intend neuromuscular scale — revised for severely affected adults (CHOP-ATEND) — and in lung function.
All of these benefits contrasted to the progressive decline seen in untreated adults.
Although the results aren’t fully consistent between studies — for example, differences in whether 6MWT scores improved — the fact that improvements were found in all studies does suggest that this Spinraza therapy can have benefits for adults with SMA.
Further studies, with larger patient populations, may allow clinicians and researchers to better understand how this treatment might benefit adult SMA patients, the investigators said.