Multiple Sclerosis (MS) is a chronic condition where the immune system attacks the protective myelin sheath surrounding nerve fibers in the central nervous system. This autoimmune attack causes inflammation and damage, disrupting communication between the brain and the body. Managing MS involves disease-modifying therapies (DMTs) designed to reduce relapses and slow disability progression. Sanofi Genzyme offers a portfolio of treatments for relapsing forms of MS, differentiated by their mechanism of action, administration route, and suitability for varying disease activity levels.
Oral Disease-Modifying Therapy
Sanofi Genzyme’s oral treatment for relapsing MS is teriflunomide (Aubagio), a convenient, once-daily pill. This medication functions as an immunomodulatory agent with anti-inflammatory properties, providing a steady, continuous effect on the immune system. Its mechanism involves the selective and reversible inhibition of the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH).
DHODH is required for the de novo pyrimidine synthesis pathway, which is necessary for the rapid proliferation of activated T and B lymphocytes. By blocking this enzyme, teriflunomide effectively reduces the growth of these activated immune cells, which are thought to drive the inflammatory damage in MS. This action reduces the number of activated lymphocytes that can enter the central nervous system, thereby decreasing overall disease activity.
The standard recommended dose for this therapy is 14 mg, taken orally once per day. Because the drug can affect liver function and blood cell counts, regular monitoring of transaminase and bilirubin levels is performed before starting treatment and monthly for the first six months. Hypertension is also a potential adverse reaction, requiring periodic blood pressure checks during treatment.
Teriflunomide is indicated for the treatment of relapsing forms of MS, including Clinically Isolated Syndrome (CIS), Relapsing-Remitting MS (RRMS), and active Secondary Progressive MS (SPMS). Due to the potential for fetal harm, the drug is contraindicated in pregnant women and females of reproductive potential who are not using effective contraception. This oral therapy is often considered a first-line option for many individuals newly diagnosed with relapsing forms of the disease.
High-Efficacy Infusion Therapy
For patients requiring a more robust intervention, Sanofi Genzyme offers alemtuzumab (Lemtrada), typically reserved for those who have had an inadequate response to other MS therapies. This medication is a monoclonal antibody targeting the CD52 protein, which is highly abundant on the surface of mature lymphocytes, including T and B cells. The binding of the antibody results in the rapid and profound depletion of these circulating immune cells.
The treatment uses a unique, short-course intravenous administration schedule designed to reset the immune system. The first course involves five consecutive days of infusion, followed by a second course of three consecutive days administered 12 months later. Following initial depletion, the immune system undergoes a process of repopulation, resulting in a newly constituted immune profile that is thought to be less inflammatory.
Due to its potency and the potential for serious adverse effects, alemtuzumab is only available through a restricted distribution system called the Risk Evaluation and Mitigation Strategy (REMS) program. This program is necessary to manage risks such as serious autoimmune conditions, including secondary autoimmune thyroid disorders and immune thrombocytopenia (ITP). Patients must undergo comprehensive safety monitoring, including regular complete blood counts, serum creatinine levels, and urinalysis for up to 48 months after the last dose.
The therapy also carries the risk of serious infusion reactions, which require the drug to be administered in a certified healthcare setting with immediate access to equipment and personnel trained to manage emergencies. There is an increased risk of certain malignancies, such as thyroid cancer and melanoma, necessitating baseline and yearly skin exams. This high-efficacy approach is considered an escalation therapy for patients with highly active or rapidly progressing disease.
Differentiating Treatment Selection and Administration
Selecting between these two therapies requires weighing differences in administration, mechanism, and risk profiles against a patient’s specific disease activity. Teriflunomide administration is straightforward, involving a continuous, daily oral dose that integrates easily into a patient’s routine. Conversely, alemtuzumab requires pulsed intravenous infusions over several days, with courses separated by a full year.
Clinicians often consider teriflunomide as a maintenance therapy or a first-line option, appropriate for patients seeking a convenient oral medication with a manageable side effect profile. Its mechanism of inhibiting cell proliferation offers a continuous, gentler form of immunomodulation. The required monitoring is frequent at the start but becomes less intensive over the long term compared to the alternative therapy.
Alemtuzumab is selected for patients with higher disease activity or those who have not responded adequately to a first-line treatment. Its mechanism involves profound, temporary immune depletion and subsequent repopulation, aiming for a more complete and lasting alteration of the disease course. This powerful effect mandates the strict, multi-year monitoring outlined in the REMS program due to the significant risk of secondary autoimmune conditions.
The final decision balances patient preference for a pill versus an infusion, the clinician’s assessment of disease aggressiveness, and the patient’s willingness to commit to the rigorous, long-term safety monitoring required for the high-efficacy infusion therapy. The two drugs represent distinct strategies for managing the immune-mediated inflammation that characterizes relapsing MS.