Change from baseline to Week 4 in JC viral load in CSF is expressed as log10 copies/mL. Negative values indicate a reduction in viral load.

Only participants with measurable baseline values are included. Post-baseline values of 'Below the Limit of Quantification' or 'Below Limit of Detection' or 'Negative' were set to 50. Log10 (50) = 1.699

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants with undetectable CSF JCV load at baseline were not included in the efficacy analysis. All other enrolled participants were included in the efficacy analysis if values for Week 4 were available.

Change from baseline to Week 8 in JC viral load in CSF is expressed as log10 copies/mL. Negative values indicate a reduction in viral load.

Only participants with measurable baseline values are included. Post-baseline values of 'Below the Limit of Quantification' or 'Below Limit of Detection' or 'Negative' were set to 50. Log10 (50) = 1.699

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants with undetectable CSF JCV load at baseline were not included in the efficacy analysis. All other enrolled participants were included in the efficacy analysis if values for Week 8 were available.

EDSS assesses disability in 8 functional systems. An overall score ranging from 0 (normal) to 10 (death) was calculated. Negative change scores indicate improvement.

Participants with values at the time frames being measured. EDSS was not required for participants who had physical or cognitive impairments that limited their ability to perform the assessment.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

The KPS Index classifies participants' functional impairment. KPS can be used to compare effectiveness of different therapies and to assess the prognosis in individual participants. KPS was recorded on an 11-point scale (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100.) where '0=Dead' and '100=Normal, no complaints, no evidence of disease'. The lower the KPS score, the worse the survival for most serious illnesses. The KPS index is subdivided into 3 categories: incapacitated (0 to 40), self-care (50 to 70), and normal activity (80 to 100).

Negative change from baseline scores indicate improved prognosis.

Participants with values at the time frames being measured. Participants with undetectable CSF JCV load at baseline by the central laboratory were not included in the efficacy analysis.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

The SDMT is a simple substitution task. The test gives participants 90 seconds to pair specific numbers with given geometric figures as a measure for screening cognitive impairment. The total score is the total number of correctly completed boxes in the time allowed. The test score range is from 0 (worst outcome) to 110 (best outcome).

Negative change from baseline scores indicates a worsening outcome.

Participants with values at the time frames being measured. SDMT was not required for participants who had physical or cognitive impairments that limited their ability to perform the assessment.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants rate their neurological function on a scale of 100 mm line, where the 0 end of the scale indicates poor neurological function and 100 indicates excellent neurological function. VAS was not required for participants who had physical or cognitive impairments that limited their ability to perform the assessment.

Negative change from baseline scores indicates a worsening outcome.

Participants with values at the time frames being measured. VAS was not required for participants who had physical or cognitive impairments that limited their ability to perform the assessment.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants with values at the time frames being measured. Participants with undetectable CSF JCV load at baseline by the central laboratory were not included in the efficacy analysis.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants with values at the time frames being measured. Participants with undetectable CSF JCV load at baseline by the central laboratory were not included in the efficacy analysis.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

Participants with values at the time frames being measured. Participants with undetectable CSF JCV load at baseline by the central laboratory were not included in the efficacy analysis.

Local standard of care participants who added mefloquine at Week 4 or Week 8 were counted as being dosed under both treatment arms.

The death event is counted under the treatment arm relative to adding mefloquine to the treatment regimen.

Safety population: All participants who enrolled in the study and were dosed, and who have at least 1 post-baseline safety assessment.

The death event is counted under the treatment arm relative to adding mefloquine to the treatment regimen.