Tofersen linked to slow, positive effects in ALS
FROM THE ENCALS MEETING 2022
The bigger picture
While acknowledging that tofersen acts on a genetic mutation found in only about 2% of ALS, Dr. Miller said the study findings carry significance for the wider ALS patient population.
“Assuming we agree there is a clinical effect here, assuming we agree that there is real stabilization of clinical function, I think if we agree on that point then we know that ALS is now a treatable disorder. And that’s a really important point. I’m not sure that we knew that before,” he said. “Yes, there are FDA-approved medications that slow down ALS a bit, but they don’t stabilize it, and if we get the target correct – and we have the correct genetic target here – there can be a substantial influence on slowing down the disease, so that’s one thing to learn for the whole ALS community.”
What lies ahead?
Asked to comment on the study, Richard Bedlack, MD, PhD, who was not involved in the research, said the findings are important and show “clinically meaningful” results. “Based on the new benefit-to-burden ratio, I believe most of my patients with SOD1 mutations will want to try this drug. I would like to be able to offer it to them. But I am curious to see what the FDA will do with these data,” said Dr. Bedlack, professor of neurology at Duke University in Durham, N.C., and director of the Duke ALS Clinic.
“Sometimes that open-label extension gives us time to see differences between patients who initially got drug and those who initially got placebo. That seems to be the case with tofersen here, and it was also the case with AMX0035 [Amylyx Pharmaceuticals Inc.], which did not show a survival benefit in the first 6 months but did in the open-label extension.” A recent FDA advisory board panel concluded there was insufficient evidence of benefit for AMX0035, he noted. “I wonder if the same concern will be raised here, necessitating confirmation in another trial. I hope not, but only time will tell.”
Dr. Miller added that these results “highlight how difficult ALS drug development still is. Among the many uncertainties in setting up a trial (targets, doses, inclusion criteria, outcomes), we still do not know how long we need to treat patients in order to see statistically significant changes in the clinical measures we use (ALSFRS-R, respiratory function, strength, survival, etc.). Most American studies are 6 months long and most European studies are 12 months long. Longer studies may be more likely to show benefits on certain measures (e.g., survival), but they cost more, they are challenged by dropouts as the disease progresses, and the idea of randomizing someone to a placebo for a whole year is psychologically difficult for patients, families, and many clinicians (myself included). So, we are seeing more studies like this one where the first 6 months are randomized, blinded, and placebo controlled, and then there is an open-label extension that lasts many months more.”
The study was sponsored by Biogen. Writing and editorial support was provided by Excel Scientific Solutions. Tofersen was discovered by Ionis Pharmaceuticals Inc. Dr. Miller disclosed ties with Biogen, Ionis Pharmaceuticals Inc., Cytokinetics, C2N, Disarm Therapeutics, and UCB Pharma. Dr. Bedlack disclosed ties with Biogen.
