There’s new hope for some people who suffer relapsing forms of multiple sclerosis (MS) — the chronic, inflammatory disease of the nervous system thought to affect some 2.8m people worldwide, which generally strikes between the ages of 20 and 40 and is twice as common in women as it is in men.
Symptoms range from the mild, such as blurred vision, and tingling and numbness in the limbs, to the more severe, including mobility problems, paralysis and vision loss, although most people with the condition do not experience severe disability.
There are several types of MS. The most common is relapsing-remitting MS, characterised by disease flare-ups and periods of remission when there is partial or total recovery, reports MedicalNewsToday.
Scientists believe MS is an autoimmune disorder, with immune cells attacking the protective myelin sheath that surrounds nerve cells. Although not hereditary, there is some evidence of genetic susceptibility, with the condition then being triggered by environmental factors.
Treatment can slow the progression of the disease but, as this is a lifelong condition, the cost can mount up, particularly for biologic medications that are effective in treating the relapsing forms of the condition.
One treatment used for people who have not responded well to first-line therapies is natalizumab (Tysabri), a monoclonal antibody: this can slow the progression of symptoms during an MS flare-up and decrease the rate of relapse in those with relapsing-remitting MS.
Now, the US Food and Drugs Administration (FDA) has approved a biosimilar form of natalizumab for people with MS and Crohn’s disease.
The new biosimilar is called Tyruko.
Tysabri works by preventing leukocytes – white blood cells that are part of the immune system – from reaching the central nervous system where they attack the myelin sheaths that surround nerve cells.
It is highly effective at preventing relapses.
Tyruko works in the same way. However, Tysabri can have side effects, the most serious of which is an increased risk of progressive multifocal leukoencephalopathy
(PML), a viral infection of the brain that usually leads to death or severe disability.
Because of this risk, everyone taking Tysabri must be part of the national TOUCH programme, designed to “minimise the risk of PML, minimise death and disability due to PML, and promote informed risk-benefit decisions regarding natalizumab use”.
Tyruko will be monitored in the same way, under an FDA risk evaluation and mitigation strategy (REMS).
Dr Barbara Giesser, neurologist and MS specialist at Pacific Neuroscience Institute at Providence Saint John’s Health Centre in California, said: “Tyruko is a biosimilar form of a medicine that has been around for almost two decades – natalizumab (Tysabri). They have the same mechanism of action, and approval by the FDA means Tyruko is thought to have very similar efficacy and safety as Tysabri.”
Tyruko more cost-effective
Biosimilars are biologic medications that are highly similar to biologics (or reference products) that have already been approved by the FDA.
They have no clinically meaningful differences from the reference product, having the same safety and effectiveness.
According to the FDA, both a biosimilar and its original biologic are made from the same types of sources (e.g, living sources); provide the same benefits when treating diseases or medical conditions; are given at the same strength and dosage, and are not expected to cause new or worsening side effects.
In 2010, the annual cost of Tysabri was around $34 000, and prices have increased since then. The biosimilar is expected to be significantly cheaper than the reference product.
Giesser explained why approval of the biosimilar is important.
“This agent is not a new class of disease-modifying therapy, and its primary potential advantage is that if it is less expensive than Tysabri, which is often the case with biosimilar medications, more people with MS may be able to access it.”
Wider access to treatment
Most people with MS have short periods of symptoms followed by long stretches of remission, with partial or full recovery. The disease is rarely fatal and most people with MS have a normal life expectancy.
Medications like Tysabri, and now Tyruko are important for dealing with the periods when symptoms are most acute, and minimising these relapses.
MedicalNewsToday article – FDA approves first natalizumab biosimilar for MS treatment (Open access)
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