This study delves into the long-term progression of Chronic Lesion Tissue (CLT) in relapsing-remitting multiple sclerosis (RRMS) patients, examining its effects on clinical and radiological indicators of disease progression.

Key Findings:

• Consistent Growth: CLT increases at a steady annual rate of 7.75%, significantly impacting brain atrophy and disability.
• Clinical Impact: Patients with higher CLT expansion exhibit faster central brain atrophy, particularly in deep grey matter, and worsening disability scores.

Implications for Clinical Trials:

• CLT expansion provides a promising biomarker for RRMS progression, offering a basis for designing smaller, targeted trials to evaluate therapies aimed at mitigating smouldering inflammation.
• Calculations show that trials targeting CLT expansion require relatively small cohorts, making them feasible and efficient.

Why It Matters:

This research highlights the potential of monitoring CLT dynamics to better understand RRMS progression, tailor interventions, and refine clinical trial design.