The FDA’s go-ahead for Roche Holding AG’s Enspryng (satralizumab-mwge) in anti-aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder had watchers of the space weighing its market odds against two therapies approved earlier: Soliris (eculizumab) from Boston-based Alexion Pharmaceuticals Inc., and the more recently cleared Uplizna (inebilizumab-cdon) from Viela Bio Inc., of Gaithersburg, Md.