Genentech Eyes Potential Approval of SMA Drug After Positive Trial Results

Spinal Muscular Atrophy

Another treatment for spinal muscular atrophy could soon be available for patients. Genentech announced this morning that its experimental SMA drug risdiplam hit the mark in the second part of the pivotal SUNFISH study of patients with Type 2 and 3 of the disease.

In the study, risdiplam was administered to SMA patients with both types of the disease who are between the ages of two and 25. The study met its primary endpoint of change from baseline in the Motor Function Measure 32 (MFM-32) scale after one year of treatment with risdiplam, compared to placebo, Genentech announced. There were no treatment-related safety findings leading to withdrawal seen in any risdiplam trial to date, the company said. Full data from the SUNFISH study will be presented at a future medical conference, Genentech said.

Genentech noted that it plans to share data from this trial, as well as other trials of risdiplam in SMA with the U.S. Food and Drug Administration, as well as other global health authorities. There are currently two other SMA treatments already on the market. Biogen’s Spinraza has been approved for all forms of SMA, types 0 through 5. Novartis’ gene therapy treatment Zolgensma was approved for patients under the age of two with bi-allelic mutations in the survival motor neuron 1 gene. Both of those drugs have a high cost for patients. Spinraza is priced at $750,000 for the first year and $375,000 for every year after. Zolgensma has a $2.1 million price tag but the treatment is a gene therapy and is viewed as a potential “one-and-done” treatment.

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“The positive outcome of this trial is an important milestone for people with Type 2 or 3 SMA, too many of whom remain untreated,” said Levi Garraway, chief medical officer and head of global product development at Roche, Genentech’s parent company. “SUNFISH is the largest placebo-controlled study ever undertaken in Type 2 or 3 SMA patients. We thank the SMA community for their partnership and look forward to sharing these results with regulators and bringing risdiplam to people living with this condition.”

For risdiplam, an investigational, survival motor neuron-2 (SMN2) splicing modifier, the SUNFISH data builds on the positive data from the first part of the FIREFISH trial in Type 1 SMA announced earlier this year. In that trial, which was also a two-part trial in infants, patients showed key motor milestones after one year of treatment with risdiplam. The second part of that trial, which is assessing efficacy as measured by the proportion of infants sitting without support after 12 months of treatment, is ongoing.

Spinal muscular atrophy is a progressive neuromuscular disease that causes devastating muscle atrophy and disease-related complications. SMA is caused by a mutation in the SMN1 gene, which codes for SMN, a protein necessary for motor neuron function. It is estimated that SMA affects about one in 11,000 babies. The disease leads to the loss of nerve cells in the spinal cord that control muscle movement. Depending on the type of SMA, an individual’s physical strength and their ability to walk, eat or breathe can be significantly diminished or lost.

Risdiplam is designed to increase and sustain SMN protein levels throughout the central nervous system and peripheral tissues of the body. In addition to the SUNFISH and FIREFISH trials, risdiplam is being studied in two additional trials. In the JEWELFISH trial, which is currently recruiting patients, risdiplam will be administered to people with SMA ranging from 6 months old to 60 years old who have been previously treated with SMA-directed therapies. The RAINBOWFISH trial, also recruiting, will investigate risdiplam in SMA-diagnosed patients from birth to six weeks of age who are not yet presenting symptoms.

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