SPS Immunotherapies

Immunotherapies used in SPS

Immunotherapy is the use of medications or other interventions to address specific abnormalities in the function of a person’s immune system.

An important part of the immune system are certain white blood cells called lymphocytes. Two types of lymphocytes are B cells and T cells. B cells make antibodies. T cells are vital in identifying and killing cells with infection and in regulating other aspects of the immune response.
 

Certain subsets of B cells and T cells can be the intended target of some immunotherapies for treating SPS.

“First Line” Immunotherapies

• Intravenous immunoglobulins (IVIg) Immunoglobulins are antibodies that impact many components of the immune system activities. IVIg has purified immunoglobulins that have been obtained from pooled human donor sources.

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• Subcutaneous immunoglobulin (SCIG) SCIG is another route of giving immunoglobulins. It is delivered by a pump system with IV tubing, infusing the immunoglobulins into the subcutaneous layer of the skin. For people on high doses of immunoglobulins, this could involve multiple infusion sites. This treatment can be self-administered, making it more convenient.

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IVIg Maintenance Therapy in GAD + SPSD

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• Intravenous methylprednisolone (Solu-Medrol) This immunotherapy is usually a short course of high dose intravenous steroids which are used for the management of some autoimmune disorders. It is sometimes followed by a more prolonged course of oral steroids (prednisolone or prednisone) that is often slowly tapered over weeks.

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• Plasma exchange (PLEX) or plasmapheresis A special catheter (central line) or port is sterilely placed into a large blood vessel. During the plasmapheresis treatment, blood comes from the patient, through the catheter to the plasmapheresis machine where it is treated and then returned to the patient. The process of plasma exchange involves “cleaning” the blood by removing some of its liquid plasma which contains antibodies. Then the rest of the patient’s blood is returned to the patient with either donated plasma or albumin to replace some of what was removed. A typical course of plasmapheresis might be 5 – 7 treatments done every other day. For those who respond, it may then be done less often as an ongoing maintenance therapy.

“Second Line” Immunotherapies

These are the immunotherapies with B cells and or T cells as the intended target.

• Rituximab – Depletes B cells. It is given by intravenous infusion using different regimens. One typical course would be to give two doses, two weeks apart, repeating about every 6 months.

• Cyclophosphamide (Cytoxan) – Targets B cells and T cells, given by intravenous infusion with various protocols.

• Mycophenolate mofetil (CellCept, Myfortic) – Oral medication which has been used as additional immunotherapy to decrease B cell and T cell growth.

• Azathioprine (Imuran) – Orally administered, decreases the number of B and T cells.

Experimental

Autologous stem cell transplants Stem cells are normal cells that have the unique ability to form many other types of cells. Stem cell transplants have been used to treat some severe autoimmune diseases. These transplants are a multi-step, complicated process where the person with the autoimmune disease becomes their own stem cell donor (autologous). The process involves receiving medication to generate an increased number of normal bone marrow stem cells, which will then be treated outside of the body and infused back into the patient to reset the immune system.

There have been several small trials of autologous stem cell transplants in SPS patients who have already responded poorly to other therapies. Results have been mixed, with some patients doing well for at least a few years. Some patients initially did well and then relapsed. Some patients have no improvement or change in their SPS symptoms.

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There are many important questions requiring further research about which patients with SPS might have the best chance of a good and sustained response to a stem cell transplant. The procedure itself is complicated and considered high-risk.