When the U.S. Food and Drug Administration (FDA) approved the disease-modifying therapy Mayzent (siponimod) for relapsing types of multiple sclerosis (MS), it specified in its label that the treatment was for people with clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), and — importantly — secondary progressive MS (SPMS) provided they have “active” disease.
The approval is good news, an MS researcher and physician said to Multiple Sclerosis News Today in an interview, but “surprising” in that the FDA’s decision was largely based on a trial that didn’t involve CIS patients and wasn’t focused on responses among particular types of SPMS.
“It’s the first time that I’ve seen in the MS field that regulators made an approval designation — active secondary progressive MS — based on an underpowered subgroup analysis,” said Robert Fox, MD, a neurologist at the Mellen Center for Multiple Sclerosis at the Cleveland Clinic.
Novartis‘ medication, as a first oral therapy approved in the U.S. for a form of SPMS, is a big step forward in MS treatment, he said. But details of the FDA’s decision caught him off guard.
Fox served on the steering committee for the EXPAND Phase 3 clinical trial (NCT01665144), on which the FDA decision was largely based. His clinic was also one of the sites treating and evaluating patients in this pivotal study.
Results of the EXPAND trial showed that Mayzent could reduce the risk of disability progression at three months (the trial’s primary endpoint, or goal) by 21% in treated SPMS patients, compared to those given a placebo. Among those with active SPMS (meaning with relapses), a 33% reduction was observed.
The treatment, an S1P modulator that works in part to keep lymphocytes from entering the brain to trigger inflammation, also decreased the annualized relapse rate by 55% and improved cognitive processing speed in all treated patients.
“What was found, and I think quite clearly found in a large-size study, was that siponimod in patients with secondary progressive MS clearly slowed the progression of clinical disability over the course of the trial,” Fox said. “It’s a statistical concept — obviously patients either progress or they don’t progress — but on an overall basis there was a 21% slowing in the rate of progression of clinical disability.”
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