Disease Modifying Therapies Withdrawal in Inactive Secondary Progressive Multiple Sclerosis Patients Older Than 50 Years (STOP-I-SEP)

Multiple sclerosis (MS) usually evolves over decades and can present several phenotypes. Approximately 85% of newly diagnosed Multiple Sclerosis (MS) patients present the Relapsing-Remitting MS (RRMS) phenotype. After a mean time of approximatively 20 years, a large majority of these patients evolve to the so-called "Secondary Progressive MS" (SPMS) phase. SPMS is characterized by an irreversible disability progression not related to relapses, although relapses could be superimposed. Nevertheless, the shift in-between RRMS and SPMS is not clear. Different subtypes of SPMS have been recently defined by F Lublin et al. This classification takes into account persistent focal inflammatory activity (active vs inactive SPMS) along with disease progression (progressing vs non-progressing SPMS). In clinical routine, it is important to identify these stages of MS as they differently respond to the disease modifying therapies (DMTs).

Introducing DMTs during the RRMS phase had consistently demonstrated a significant impact on the annual relapse rate (ARR) and on the short-term disability progression. Conversely, during the SPMS phase, the impact of DMTs remained uncertain on disability progression, especially in older patients, with "inactive" disease. As a matter of fact, the DMTs are considered to be anti-inflammatory by nature, but the focal inflammation reduces with age and disease duration.

In addition, the DMTs have side effects and cost approximately 10,000 euros per year and per patient. In this context, the usefulness of continuing DMTs in "inactive" SPMS patients older than 50 years is questionable.

In a preliminary retrospective study conducted at our Institute which enrolled 100 SPMS patients, the ARR remained stable 3 years after treatment withdrawal (0.07, 95% CI [0.05, 0.11]), relative to the 3 years prior to treatment withdrawal (0.12, [0.09, 0.16]). EDSS scores were available for 94 patients The percentage of patients experiencing a significant increase of their EDSS score during the 3 years after treatment withdrawal also remained stable compared to the 3 years prior treatment withdrawal. These preliminary data support the safety of DMTs withdrawal in selected SPMS patients. However, further prospective studies are needed to provide evidence-based guidelines for daily practice.

This randomized controlled clinical trial thus aims to compare SPMS patients older than 50 years without evidence of focal inflammatory activity for 3 years, stopping DMTs versus patients with the same criteria still receiving treatment. We hypothesize that stopping DMTs will not induce an increased risk of disability progression or relapse in SPMS patients but will improve their quality of life and have an impact on treatment-related costs.

So far, the impact of DMTs withdrawal in a selected SPMS population has not been explored. Having evidence-based recommendations on the treatment management of these patients is essential, considering the consequences in terms of disability, relapses, side effects, quality of life and costs. DMTs in MS are now available since 20 years, with an increasing number of approved molecules. As a matter of fact, this question concerns a large number of patients: a retrospective analysis of patients included in the Rennes EDMUS database allowed to identify 71 SPMS patients older than 50 years and without evidence of focal inflammatory activity for 3 years actually undergoing a DMT.

For evident conflict of interests, the pharmaceutical firms will not promote or fund clinical trials on treatment withdrawal. A randomized controlled study initiated by academia and financed by public funding should be performed to explore these questions. We will evaluate the impact of these changes from the patient and the health system's points of view. The results of this clinical trial will lead to a concrete change in clinical practice.