Abstract
Recent advances in multiple sclerosis (MS) management have shifted perspectives on treatment strategies, advocating for the early initiation of high-efficacy disease-modifying therapies (heDMTs). This perspective review discusses the rationale, benefits, and challenges associated with early heDMT initiation, reflecting on the obsolescence of the traditional "first-line" and "second-line" treatment classifications. The article emerges from the last update of the consensus document of the Spanish Society of Neurology on the treatment of MS. During its development, there was a recognized need to further discuss the concept of treatment lines and the early use of heDMTs. Evidence from randomized controlled trials and real-world studies suggests that early heDMT initiation leads to improved clinical outcomes, including reduced relapse rates, slowed disease progression, and decreased radiological activity, especially in younger patients or those in early disease stages. Despite the historical belief that heDMTs involve more risks and adverse events compared to moderate-efficacy DMTs (meDMTs), some studies have reported comparable safety profiles between early heDMTs and meDMTs, though long-term safety data are still lacking. The review also addresses the need for a personalized approach based on patient characteristics, prognostic factors, and preferences, explores the importance of therapeutic inertia, and highlights the evolving landscape of international and national guidelines that increasingly advocate for early intensive treatment approaches. The article also addresses the challenges of ensuring access to these therapies and the importance of further research to establish long-term safety and effectiveness of DMTs in MS.