Nusinersen (Spinraza) for Spinal Muscular Atrophy May Help Older Children

 A drug used to treat a rare and deadly muscle-wasting disease in children still improves muscle control even if treatment begins at a later age, a new study found.

Spinal muscular atrophy (SMA) is a leading genetic cause of death in infants worldwide. It attacks nerve cells in the spinal cord, leading to muscle weakness, which can affect breathing, swallowing, walking and head control.

SMA type 1 is the most common and severe form of the disease. It starts before 6 months of age, with infants never gaining the ability to sit up. The median survival rate is eight to 14 months. That means half have shorter lives, half longer.

Previous studies focused on children 7 months old or younger.

This new study included 33 children, ages 8 months to 8 years, with SMA type 1. They were given an injection of the drug nusinersen (Spinraza) into the spinal canal.

The drug increases production of a protein essential for motor neurons in the spinal cord to survive. It was approved by the U.S. Food and Drug Administration in December 2016, and is the first and only approved treatment for all types of SMA.

Six months after the injection, all 33 children had significant muscle control improvements, even the oldest, the researchers reported.

Five patients, ranging from 18 months to 4 years of age when they got their first injection, were able to sit up without support for the first time.

The study was published Aug. 29 in the online issue of the journal Neurology.

"This study is exciting because we found participants had motor function improvement six months after receiving treatment, even an 8-year-old participant," study author Dr. Laurent Servais said in a journal news release.

Servais is a pediatric neurologist at Pitie-Salpetriere Hospital in Paris, France, and Citadelle Hospital in Liege, Belgium.

"The overall response was to the same extent as that in the previously studied younger population," he noted.

"Spinal muscular atrophy type 1 is a devastating disease, and it is encouraging to see that nusinersen may also help people who are at a later stage in the disease process," Servais said.

More research is needed, he said, to find out if genetic factors affect differences in patients' response to treatment.

Ref : https://en.wikipedia.org/wiki/Nusinersen

FDA approves first drug to treat children and adults with spinal muscular atrophy

The U.S. Food and Drug Administration today approved Spinraza (nusinersen), the first drug approved to treat children and adults with spinal muscular atrophy (SMA), a rare and often fatal genetic disease affecting muscle strength and movement. Spinraza is an injection administered into the fluid surrounding the spinal cord.

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"There has been a long-standing need for a treatment for spinal muscular atrophy, the most common genetic cause of death in infants, and a disease that can affect people at any stage of life," said Billy Dunn, M.D., director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research. "As shown by our suggestion to the sponsor to analyze the results of the study earlier than planned, the FDA is committed to assisting with the development and approval of safe and effective drugs for rare diseases and we worked hard to review this application quickly; we could not be more pleased to have the first approved treatment for this debilitating disease."

SMA is a hereditary disease that causes weakness and muscle wasting because of the loss of lower motor neurons controlling movement. There is wide variability in age of onset, symptoms and rate of progression. Spinraza is approved for use across the range of spinal muscular atrophy patients.

The FDA worked closely with the sponsor during development to help design and implement the analysis upon which this approval was based. The efficacy of Spinraza was demonstrated in a clinical trial in 121 patients with infantile-onset SMA who were diagnosed before 6 months of age and who were less than 7 months old at the time of their first dose. Patients were randomized to receive an injection of Spinraza, into the fluid surrounding the spinal cord, or undergo a mock procedure without drug injection (a skin prick). Twice the number of patients received Spinraza compared to those who underwent the mock procedure. The trial assessed the percentage of patients with improvement in motor milestones, such as head control, sitting, ability to kick in supine position, rolling, crawling, standing and walking.

The FDA asked the sponsor to conduct an interim analysis as a way to evaluate the study results as early as possible; 82 of 121 patients were eligible for this analysis. Forty percent of patients treated with Spinraza achieved improvement in motor milestones as defined in the study, whereas none of the control patients did.

Additional open-label uncontrolled clinical studies were conducted in symptomatic patients who ranged in age from 30 days to 15 years at the time of the first dose, and in presymptomatic patients who ranged in age from 8 days to 42 days at the time of first dose. These studies lacked control groups and therefore were more difficult to interpret than the controlled study, but the findings appeared generally supportive of the clinical efficacy demonstrated in the controlled clinical trial in infantile-onset patients.

The most common side effects found in participants in the clinical trials on Spinraza were upper respiratory infection, lower respiratory infection and constipation. Warnings and precautions include low blood platelet count and toxicity to the kidneys (renal toxicity). Toxicity in the nervous system (neurotoxicity) was observed in animal studies.

The FDA granted this application fast track designation and priority review. The drug also received orphan drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

The sponsor is receiving a rare pediatric disease priority review voucher under a program intended to encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases. A voucher can be redeemed by a sponsor at a later date to receive priority review of a subsequent marketing application for a different product. This is the eighth rare pediatric disease priority review voucher issued by the FDA since the program began.

Spinraza is marketed by Biogen of Cambridge, Massachusetts and was developed by Ionis Pharmaceuticals of Carlsbad, California.

A tetracycline derivative for the treatment of Spinal Muscular Atrophy .....

A chemical cousin of the common antibiotic tetracycline (PTK-SMA1) might be useful in treating spinal muscular atrophy (SMA), a currently incurable disease that is the leading genetic cause of death in infants. This is the finding of a research collaboration involving Adrian Krainer, Ph.D., of Cold Spring Harbor Laboratory (CSHL) and scientists from Paratek Pharmaceuticals and Rosalind Franklin University of Medicine and Science.

About SMA :

SMA is caused by mutations in a gene called Survival of Motor Neuron 1 (SMN1), resulting in a decrease in the levels of SMN protein in the motor neurons of the spinal cord -- the cells that control muscle activity. Without the protein, these neurons degenerate, and infants born with the mutations progressively lose the ability to move, swallow, and breathe. There are no approved therapies for the treatment of SMA.

Mode of action of PTK-SMA1 :

The new molecule boosts the levels of SMN protein in cells by fixing a mistake in a cellular processing mechanism called RNA splicing. The drug candidate targets the splicing of a gene called SMN2, which is essentially a back-up copy to the SMN1 gene that’s mutated beyond repair in SMA patients. SMN2 doesn’t compensate for the loss of SMN1, however, because it produces too little functional protein. Most of the protein that is produced is missing a single important piece, without which the protein rapidly degrades. The significance of this finding is in the fact that “PTK-SMA1 is the only small molecule known to specifically alter RNA splicing by directly and solely targeting the splicing reaction” . Other molecules that affect splicing also affect other cellular processes, thus diluting their potency, and potentially increasing the risk of side effects. PTK-SMA1 has the added advantage of being a derivative of tetracyclines, which are nontoxic and have demonstrated safety in humans...

Source : http://stm.sciencemag.org/content/1/5/5ra12.abstract.