Risdiplam is in clinical development for the treatment of spinal muscular atrophy (SMA). SMA is a severe, inherited, neuromuscular lethal disease that gets worse over time. Patients with the disease lack a survival motor neuron (SMN) 1 gene and fewer copies of SMN2. This gene produces a protein called SMN protein, which is essential for the normal functioning and survival of motor neurons (nerves from the brain and spinal cord that control muscle movements). SMA is usually diagnosed within the first few months of life for the most severe subtype (type I). 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. SMA causes the muscles to fall into disuse, leading to muscle wasting (atrophy) and weakness, and in its most common form (type I), loss of swallowing function, breathing failure and death within the first few years of life. There is currently no cure for SMA but there are treatments to help manage the symptoms.
Risdiplam is an investigational, oral medicine that is designed to increase SMN protein levels in the central nervous system and throughout the body and thereby reducing the symptoms of the disease. If licensed risdiplam will offer a treatment option for paediatric and adult patients with SMA.
Tofersen (BIIB067) is in clinical development for the treatment of amyotrophic lateral sclerosis (ALS – also known as motor neurone disease) caused by mutations in the SOD1 gene (SOD1-ALS). ALS is a progressive disease of the nervous system, where nerve cells in the brain and spinal cord that control voluntary movement gradually deteriorate, causing loss of muscle function and paralysis. ALS is a debilitating and life-threatening disease. The gradual loss of neurons leads to a paralysing effect on muscles used for breathing, which usually leads to death from respiratory failure.