Continuing last week’s theme of good news, there’s a new initiative by Kyowa Kirin (in its various iterations internationally) to combine natural history study data about XLH from all around the world. It’s called APEX, and it combines data from the US (DMP), Europe/Israel (IXLHR), and Japan and South Korea (Sunflower).
Ideally, we’d have just one natural history study for XLH, available around the world, collecting exactly the same data and asking exactly the same questions everywhere. That way, we’d know that, for example, the blood tests in one country were being performed in the same way as the next country, e.g., that phosphorus levels were tested after fasting. (I think they’re probably doing that already for the phosphorus tests, but I’m sure there are other, less well-known ways for the test results to end up not being exactly comparable.)
Unfortunately, international studies are complicated. The XLH Network started out trying to do a natural history study in 2018 that was going to be just the US initially (because we had help making sure we followed all the medical/privacy laws here), with the intention of then expanding to other regions of the world, but the challenges with differing privacy and health laws around the world were just too much to overcome.
APEX is a good start toward collecting data all around the world, but there are still some limitations, due to variations among independently established studies. It appears that the individual principal investigators are starting to collaborate more to make the data-collection match (and to expand on the questions being asked), and I hope that continues. For now, though, this is a good start, with more than 1500 patients enrolled!
Personally, I love that the article does NOT refer to the old treatment (phosphorus/calcitriol) in any terms that would suggest it was somehow standard or preferable to burosumab. They say simply, “Two treatment options are currently available for XLH …” Eventually, we should get to the point where burosumab becomes the default, and phos/calcitriol becomes more of an “if you can’t access burosumab, then phos/calcitriol is better than nothing.” But for now, simply presenting them equally is a big improvement over the previous approach, which was to present phos/calcitriol as the default, and then sort of include a post script for burosumab, but in such a way that it sounded experimental and risky.
The linked article is just an overview of the baseline data and how it was obtained. There’s little in the way of new and surprising information. One thing I’d like to see in the future though is a breakdown of the adult demographics. There’s potentially a BIG difference in the experiences of a twenty-something XLHers and an eight-something XLHer, but they’re lumping all of the adults together. We know it’s a progressive disorder, so we need to see how the numbers change with each decade of adulthood. (They may plan to do this already, so this isn’t a critique, just a wish list item from me.)
All in all, really valuable work, and I look forward to seeing further analysis as the data collection continues and insights improve.
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Please note that the author is a well-read patient, not a doctor, and is not offering medical or legal advice.
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