Multiple Sclerosis (MS) is a chronic, autoimmune disease affecting the central nervous system, including the brain and spinal cord. The immune system mistakenly attacks myelin, the protective covering around nerve fibers, causing inflammation and damage. This damage disrupts the flow of information between the brain and body, leading to neurological symptoms. Infusion therapy is a potent method for administering disease-modifying therapies (DMTs) designed to reduce the frequency and severity of relapses and slow disease progression.
The Delivery Method and Biological Function
Infusion therapy involves administering medication directly into the bloodstream through an intravenous (IV) line, allowing for rapid and precise delivery. This route is necessary because many effective DMTs for MS are complex biologic drugs, such as monoclonal antibodies. These large protein molecules would be destroyed by the digestive system if taken orally. Delivering these medications directly into the vein ensures a higher, more consistent dose reaches the target sites, maximizing their therapeutic effect.
These infused biologic drugs modulate the immune system’s abnormal response that causes MS. The mechanism often involves targeting specific immune cells, primarily lymphocytes, implicated in the inflammatory cascade. For instance, some treatments selectively deplete B-cells, a type of lymphocyte that contributes to nerve damage by activating pro-inflammatory processes. By reducing these harmful immune cells, the therapies suppress the inflammatory attack on the central nervous system, reducing new lesions and slowing disability progression.
Other treatments prevent immune cells from crossing the blood-brain barrier, a specialized membrane separating circulating blood from the brain and spinal cord tissue. By blocking this entry, the therapy inhibits immune cells from initiating an inflammatory attack within the central nervous system.
Key Medications Administered via Infusion
Several FDA-approved disease-modifying therapies for MS are administered via infusion, each having a distinct mechanism. Natalizumab (Tysabri) is approved for relapsing forms of MS, including relapsing-remitting MS (RRMS). This medication blocks immune cells from passing out of the bloodstream and into the brain and spinal cord, effectively quarantining the inflammatory activity.
Ocrelizumab (Ocrevus) is approved for both relapsing forms of MS and primary progressive MS (PPMS). This drug is a monoclonal antibody that selectively targets B-cells expressing the CD20 protein on their surface. By depleting these B-cells, Ocrevus reduces relapses in RRMS and slows disability progression in PPMS, making it the only DMT approved for PPMS.
Alemtuzumab (Lemtrada) is typically reserved for patients with relapsing MS who have had an inadequate response to at least two other MS medications. This potent therapy severely reduces the numbers of both B and T lymphocytes. Following treatment, the immune system rebuilds itself, ideally without the inflammatory cells that cause MS damage. Ublituximab-xiiy (Briumvi) is a newer treatment for relapsing MS that also targets the CD20 antigen on B-cells, offering a twice-yearly option.
The Patient Experience and Treatment Schedule
Infusion therapy for MS is typically administered in a specialized infusion center, hospital outpatient center, or doctor’s clinic; some patients may qualify for at-home infusions. Prior to the infusion, patients are often given pre-medications, such as corticosteroids, antihistamines, and acetaminophen, to minimize the risk of an infusion-related reaction. The treatment begins with the insertion of an intravenous catheter, and the medication is administered at a controlled pace.
The duration of the infusion session varies significantly depending on the specific drug used. For example, a Natalizumab infusion usually takes about one hour, while Ocrelizumab infusions can take a few hours. Alemtuzumab involves daily infusions over several consecutive days for the initial course. Throughout the procedure, a nurse monitors the patient for signs of an adverse reaction, such as changes in vital signs or symptoms like a rash or difficulty breathing.
Treatment frequency is a significant advantage, often requiring less frequent dosing compared to daily oral or injectable medications. Ocrelizumab and Ublituximab-xiiy are typically given every six months after the initial dosing schedule. Natalizumab is usually administered every four weeks, while Alemtuzumab involves two treatment courses given one year apart. Following the infusion, patients are monitored for a period to ensure there are no immediate post-infusion reactions before they are cleared to leave.