Lymphocyte Changes in Animals Treated with Natalizumab
In a study analyzing data from 627 subjects, treatment with natalizumab resulted in a significant increase in lymphocyte counts compared to placebo. Additionally, individuals without anti-drug antibody responses exhibited substantial increases in lymphocyte counts, indicating a potential biomarker for monitoring treatment.
- Tags
- #MSResearch
- Most relevant to
- —
- Human efficacy
- Not yet assessed
- Mechanism
- Not yet assessed
- Evidence strength
- Not yet assessed
- Outcome
- Not yet assessed
Why it matters
These findings suggest that measuring lymphocyte counts could help identify patients who are responding well to natalizumab and those who may develop anti-drug antibody responses, potentially improving patient management.
What this does not prove
The study suggests a correlation between lymphocytosis and treatment responses but does not establish causation between these factors.
Next milestone
No next milestone was established from the available source.
Study facts
- Study design
- Not reported
- Participants / samples
- 627 · n = 627 natalizumab vs n = 315 placebo in the AFFIRM clinical trial; n = 185 from the Cardiff MS register
- Randomised
- Not reported
- Controlled
- Not reported
- Primary endpoint met
- Not reported
- Relevant MS type
- Not reported
- Publication date
- 2026-10-17
- Evidence reviewed
- Abstract only
- Regulatory approval
- Not reported
- Research areas
- Not classified
Original sources
- Primary evidenceLymphocytosis as a biomarker for natalizumab treatment response in multiple sclerosis: The link with anti-drug antibodies. ↗DOI: 10.1177/13524585261495351
Supporting passages (8)
sample size627
sample size basisMETHODS: Lymphocyte counts and immunogenicity data from the pivotal AFFIRM clinical trial (n = 627 natalizumab vs n = 315 placebo) and real-world data from the Cardiff MS register (n = 185) were analysed to assess the relationship between lymphocyte counts, anti-drug antibody responses, drug levels and disease activity.
publication date2026-10-17
interventionNatalizumab
primary endpointCONCLUSION: The absence of relative lymphocytosis is associated with anti-drug antibody responses and may provide a simple biomarker to prompt anti-drug antibody testing before disease breakthrough occurs.
findingsRESULTS: Natalizumab treatment induced an absolute change in lymphocyte counts by week 12 (1.40 ± 0.92 vs -0.05 ± 0.62 × 109 cells/L in natalizumab vs placebo; p < 0.0001) that was absent in the persistent anti-drug antibody group (-0.12 ± 0.60 × 109 cells/L).
findingsIncreases in lymphocyte counts by ⩾ 0.8 × 109 cells/L from the baseline discriminated individuals without anti-drug antibody responses with high sensitivity (≥ 84%) and specificity (≥ 91%).
limitationsTitle: Lymphocytosis as a biomarker for natalizumab treatment response in multiple sclerosis: The link with anti-drug antibodies.
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