This reminded me of something I'd read before and a quick search shows that they were supposedly working on something that was called "SA55+SA58" earlier. Way out of my wheelhouse, but I'm wondering if it's just nomenclature or if they moved on from the SA55 component. I'm not sure monoclonal antibodies are the way out of this, but I'll jump on just about any hope bandwagon.
https://www.biorxiv.org/content/10.1101/2022.08.03.499114v1.full