An expert neurologist reviews efficacy and safety data of rozanolixizumab, an FcRn-targeting agent approved for treatment of gMG, as well as how it differs from efgartigimod.
James F. Howard Jr, MD: A second FcRn [neonatal Fc receptor] inhibitor was recently approved. Rozanolixizumab—we call it Rosie for short because it’s a real tongue twister—recently gained approval in the US to treat generalized AChR [acetylcholine receptor]– and muscle-positive myasthenia gravis. It is a subcutaneously administered drug, but it’s not an injection. Rather, it’s an infusion, whereas of efgartigimod subcu[taneous] is 5.6 cc administered subcutaneously in concert with hyaluronidase, which sort of breaks down the surrounding collagen that allows larger volume to be injected in 60 to 90 seconds, much as we do in oncology. Rosie requires an infusion over a period of many minutes to get it into the system. Its efficacy appears similar to [that of] efgartigimod. We see rapid reductions in IgG level in terms of antibody level as well as improvements in the MG ADL [myasthenia gravis activities of daily living] health score and the QMG [qualified MG] score. There is no head-to-head comparison between the 2, and there are no data to suggest or support preferences among patients between the 2. So we’re still too early in the game. Rosie is a full-size antibody. It’s not a small Fc fragment. And some have suggested that that may play a role in terms of the adverse event profile that will be seen. So the adverse event profile was quite similar to what was seen in the efgartigimod trials. Percentages are different to a degree, but the numbers are different. So again, we can’t draw a one-to-one comparison. My belief is that many of the FcRns will do the same thing in terms of immunoglobulin or IgG antibody clearance. And the differentiating features are going to be in terms of adverse event profiles, as we accumulate data over a longer period of time. The logistics of administration, etc.
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