Might Hydroxychloroquine Treat Primary Progressive Multiple Sclerosis?

More-efficacious therapies for progressive forms of multiple sclerosis (MS) remain an unmet need. Hydroxychloroquine (HCQ) is an antimalarial drug that reduces microglial activation. Of 49 patients with primary progressive (PP) MS recruited for this single-center, open-label study, 40 patients finished the 18-month study. Participants received 200-mg tablets of HCQ twice daily. The prespecified analysis determined that “success” would be if worsening of timed 25-foot walk (T25FW) occurred between 6 and 18 months of treatment in fewer than 10 of the first 35 patients to finish the trial.

At 18 months, 8 of 35 patients had worsened, meeting the prespecified endpoint. Adverse events (AEs) were encountered in 82%, 12% had a serious AE, and 5 par…