In recent years, with the development of a class of treatments called “monoclonal antibody,” a whole new world of treatment options has opened up, and much of that world is populated by rare disorders like XLH.
A monoclonal antibody is an antibody (no kidding, right?) that’s is cloned from a single specific cell. It’s designed to bond with a protein (what you may think of as a hormone) to prevent that protein from doing its job. You can think of proteins as message-carriers, telling other proteins and organs what to do. You can easily identify which treatments are monoclonal antibodies, since their generic names (marketing names are different) end in the acronym for monoclonal antibody, mab. One of the best-known is denosumab, which is used to treat osteoporosis.
You’re probably already ahead of me with another example: burosumab, known commercially as Crysvita. While the osteoporosis antibody prevents a protein from decreasing calcium in bones, burosumab prevents the protein/hormone FGF23 from causing phosphate wasting.
We’re just starting to see what is likely to be an avalanche of additional uses for monoclonal antibodies, and already there are two whole new categories of treatments that are likely to help rare disorders: gene editing and cell editing. There’s already been preliminary research into a possible way to treat XLH with gene editing, and you can read what little has been published about it, on page 16 here. Bottom line: gene editing for XLH is being researched by scientists in Europe, with encouraging results in a strain of mice that have genetic hypophosphatemia. Instead of trying to make the body stop producing too much FGF23 (a Herculean task), instead, the researchers found a way to make the body to produce its own monoclonal antibody that binds with FGF23 to stop the phosphate-wasting. Ingenious!
I’ll have more to say about gene editing and how it works once I wrap my head around the science better. For now, two things to keep in mind: 1) it’s coming, and 2) it’s going to be life-changing for so many people. Unlike monoclonal antibody treatment, gene editing is a “one and done” treatment, not a monthly (or twice-monthly) injection for life!
I don’t expect to benefit from gene editing personally (I’ll be too old by the time it’s available), but I do expect to see it being used for other XLHers in my lifetime. It won’t just happen if we don’t advocate for it though. Some of the challenges I foresee include: 1) educating potential patient-volunteers about the risks/benefits of participating in the clinical trials for gene editing; 2) making sure the research is inclusive of the autosomal hypophosphatemias, and any other relevant disorders, not limiting it to x-linked hypophosphatemia, so as to maximize the potential benefits and spread the cost of the clinical trials across a larger patient population; and 3) overcoming the medical community’s persistent, false understanding of the cost/benefit ratio of treating XLHers, especially with respect to adult patients who continue to be viewed as not deserving of expensive treatment.
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The author is a well-read patient (and reading more about gene editing now!), not a doctor, and is not providing medical or legal advice.
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