They are testing another set of CFTR modulators (from Sionna Therapeutics) in an effort to find a treatment for people who aren't eligible for, or cannot tolerate, Vertex modulators. Only in Ph 2 at the moment, but they seem to actually be more effective in normalizing CFTR function than the miraculous Vertex drugs! (Also, some people can tolerate the Vertex drugs at a lower dose, so that might be worth looking into. Alyftrek, the latest generation of Vertex drugs, might be worth a try as well.)