Rare Neurological Diseases: Spinal Muscular Atrophy and Huntington's Disease - Episode 18
Surya Singh, MD: I think the payer’s perspective on the currently single-approved therapy for SMA [spinal muscular atrophy], and then looking forward, having multiple treatment options available starting in the next several weeks with the potential approval of Zolgensma [onasemnogene abeparvovec-xioi], is that, No. 1, our members or payers’ members are for the first time, in this specific instance, able to sort of realistically have hope of their child, in most cases, doing far better than they did before. That’s the biggest headline message of, “Hey, this is what we’re supposed to be doing in medical science.” Clinical care of patients is—I don’t want to call them the poster vulnerable population—for a population of a rare condition that has some unique characteristics, but it is really the first time they have treatment. So that’s fantastic.
I think one of the things that’s very challenging about this scenario, before I get to just talking about cost, is assessment of value. We don’t know what the longevity and durability of the treatment are. People usually think about longevity in terms of the patient. But here, as we’re just about on the cusp of sort of viral delivered gene therapy, at the onset really, or as close to the onset of the clinical manifestations of the disease being administered, the question becomes, does this method for producing the protein that we want continue to work? Or does the body find some way to be able to decrease those levels? And what happens then? Does it require a boost?
Without getting into a lot of the nitty-gritty science of it, which is incredibly fascinating and impactful, there are a lot of questions about what happens over a certain period of time. The implication of that from the payer perspective is that since we’re dealing with 2, maybe 3 different mechanisms of action between the viral AAV [adeno-associated virus]—delivered gene therapy in the antisense oligonucleotide treatments already on the market and then future treatments that are also in the pipeline, the question of combination therapy becomes important.
In the 12 patients who received the gene therapy, higher-dose gene therapy, after the follow-up period of 24 months, 5 of them went on to receive nusinersen. I won’t even dub it a cost perspective, but really from a value perspective, the question is, how much benefit incrementally does that combination give you? Regardless of what the price of the gene therapy is, if it’s $1.5 million or $4 million, if you add on to that—$750,000 in year 1 and then somewhere about $375,000 or $500,000 in every subsequent year—you’re dealing with these massive numbers. Because we’re progressing science, as more combination therapies become available, that becomes tougher to wrestle with when it’s not just SMA alone. It’s 8, then 20, then 40, then 55 other things over the next 5 years or so.
I would say that the payer’s definition of disease modification really depends heavily on what the expected trajectory is for that patient. With something like this, with spinal muscular atrophy, the trajectory of each patient is just that—a trajectory. You can categorize them, and that’s the purpose in some ways of the diagnostic category of types 1 through 4, or type 0—presymptomatic. But I think the best answer to that is that, yes, absolutely, no change in milestones might be considered a win. It might be considered real modification of the disease course.
I think payers generally look at it as, “Is it a modification? Is it a difference in trajectory for this patient individually when it’s something that’s as variable and coarse as this SMA is?”