Rationale for Correct Answer

The correct answer is: Natalizumab is FDA-approved for active SPMS but not nonactive SPMS

Currently, all DMTs approved for the treatment of RRMS also have an indication for active SPMS. In contrast, ocrelizumab is the only DMT that is currently FDA-approved for the treatment of PPMS, and no DMTs have indications for the treatment of nonactive SPMS.

References:
Amezcua L. Continuum (Minneap Minn). 2022;28:1083-1103.