Effects of Oral Cladribine on TSPO Availability in Individuals with RRMS
In a small study, 14 participants with relapsing-remitting multiple sclerosis (RRMS) showed a 21% increase in TSPO availability in normal-appearing white matter and a 16% increase in the whole brain over 18 months. Additionally, their median annualized relapse rate significantly decreased from 0.67 to 0.00, and serum neurofilament light chain levels improved.
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Why it matters
These findings suggest that cladribine may affect glial activation and relapse rates in RRMS, but the small sample size and preliminary nature of the data limit the conclusions that can be drawn.
What this does not prove
This is a small, single-arm pilot study, and findings may not indicate comprehensive efficacy or safety of cladribine in managing RRMS pathology.
Next milestone
No next milestone was established from the available source.
Study facts
- Study design
- Interventional
- Participants / samples
- 14 · enrolled participants
- Randomised
- No
- Controlled
- Yes
- Primary endpoint met
- Not reported
- Relevant MS type
- Not reported
- Publication date
- 2026-09-30
- Evidence reviewed
- Abstract only
- Regulatory approval
- Not reported
- Research areas
- Neuroinflammation
Original sources
- Primary evidenceImpact of Oral Cladribine on TSPO-PET-Measurable Immune Cell Activation in Multiple Sclerosis. ↗DOI: 10.1007/s40120-026-01044-5
Supporting passages (15)
study phaseThis study was registered on ClinicalTrials.gov (NCT04239820) on January 21, 2020.
study designIn this prospective, single-arm pilot study, we investigated the effect of oral cladribine on glial activation using 18 kDa translocator protein (TSPO) positron emission tomography (PET) in a real-world, longitudinal RRMS cohort.
subjectsMETHODS: People with RRMS initiating oral cladribine underwent TSPO-PET with [11C]PK11195, 3-T brain magnetic resonance imaging (MRI), serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) measurements, and clinical assessments at baseline and 18 months.
sample sizeFourteen people with RRMS and 14 healthy controls were enrolled.
sample size basisFourteen people with RRMS and 14 healthy controls were enrolled.
randomizedIn this prospective, single-arm pilot study, we investigated the effect of oral cladribine on glial activation using 18 kDa translocator protein (TSPO) positron emission tomography (PET) in a real-world, longitudinal RRMS cohort.
controlledRESULTS: Fourteen people with RRMS and 14 healthy controls were enrolled.
peer reviewedJournal: Neurology and therapy
research categoriesexploratory findings raise the possibility that cladribine may have limited ability to control smoldering pathology.
publication datePublication date: 2026-09-30
comparatorRESULTS: Fourteen people with RRMS and 14 healthy controls were enrolled.
primary endpointThe primary outcome was change in TSPO availability quantified as a percentage of TSPO-active voxels and distribution volume ratio.
follow upMETHODS: People with RRMS initiating oral cladribine underwent TSPO-PET with [11C]PK11195, 3-T brain magnetic resonance imaging (MRI), serum neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) measurements, and clinical assessments at baseline and 18 months.
findingsOver 18 months, TSPO availability quantified as percentage of TSPO-active voxels increased 21% in normal-appearing white matter (NAWM) (mean [95% CI] change 1.2 [0.2-2.3]; p = 0.026) and 16% in the whole brain (mean [95% CI] change 0.9 [0.01-1.8]; p = 0.047).
limitationsThis possibility warrants further investigation in larger prospective studies.
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