People considering treatment will find it confusing that there are in fact two different types of HSCT available. Understanding what differentiates Myleoablative from Non-Myleoablative HSCT is helpful. It will help you to decide which type of HSCT is appropriate for your specific needs, as well as where to go for treatment. On the whole most facilities offering this treatment will opt for one type or the other. There are currently no facilities that offer both kinds of HSCT.
WHAT IS THE DIFFERENCE IN THE TWO TYPES OF HSCT?
MYLEOABLATIVE and NON-MYELOABLATIVE HSCT are both equally respected forms of treatment. Both types ablate (destroy) the lymphocytes in the body that are self-intolerant. These are responsible for the underlying nerve damage/ destruction. Lymphocytes are the white blood cells that in normal circumstances destroy bacteria and other harmful substances in the blood. In terms of MS these usually helpful cells become ‘rogue’. They become intent on attacking the Myelin sheath that surrounds and protect our nerves. Both types of HSCT remove of these errant blood cells. Once removed the process of HSCT replaces them with ‘Naive’ ones that are behave correctly!
Myeloablative HSCT is the more stringent type of treatment. This type of HSCT is intended to completely destroy the body’s (auto reactive) lymphocytes. It also destroys the bone marrow. Myleoablative HSCT most commonly incorporates a BEAM (Carmustine, Cytarabine, Etoposide, Melphalan) chemotherapy protocol. The chemotherapy is administered over a period of six days. ATG is often added for a couple of days as a supplementary rather than essential lymphoablation. Many HSCT doctors consider Myleoablative to be the most ‘reliable’ form of HSCT. The protocol is destroys the lymphocytes more completely and ultimately reduces the chance of any of the ‘baddies” surviving!
The Non-Myleoablative protocol varies according to the doctor performing it. Generally speaking the procedure is less harsh on the body. During the treatment the Lymphocytes are not entirely eliminated. Instead they are “diminished” to a threshold level below which autoimmune-mediated damage occurs. With this form of HSCT the bone marrow is not completely wiped out making the treatment less dangerous. The patient is allowed to recover more easily.
This “gentler” chemotherapy has a lower mortality rate. However the trade off is that compared with the Myeloablative protocol there remains a proportion of patients (20-25%) that fail. This means is that the treatment does not succeed in destroying all of the lymphocytes necessary to halt the disease. If this happens “top-ups” of cyclophosphamide infusions (more chemo), are administered post-transplantation. Re-treatments often address this issue. Using “top-ups” is very common with many facilities. It will cause an MS patient that has not responded favorably back into remission.
Thoughts among Hematologist’s until recently have been that if you have a progressive form of MS (PPMS or SPMS) Myleoablative HSCT has been the most effective form of treatment.
The general trend however, with treatment today is a movement towards non-myleoablative as a more favored treatment around the world. It is less harsh on the body and recovery is much faster. Ironically, there are currently no places that offer Myleoablative HSCT to treat progressive cases of MS. The facilities that use Myleoblative HSCT are all signed up to the EBMT and treat only Relapse Remitting forms of MS.
In the past few years many new facilities performing HSCT have opened up. These are located all over the world. Each one performs their own specific form of HSCT. Each Hematologist has a unique preferred protocol. Non-Myleoablative HSCT has emerged as the most popular form of HSCT. It is exciting to see very successful results with Non-Myleoablative HSCT for PPMS and other progressive cases. The Maximov Facility in Russia regularly treats progressive cases. The protocol is updated regularly. It is constantly being tweaked and improved. In Russia specifically Dr. Fedorenko prides himself on customizing the treatment to suit each new patient. The fact that Non-Myleoablative HSCT is am easier procedure to endure, coupled with faster treatment, and recovery time, continue to popularize this option. It also enables people who are older or perhaps less robust to get treatment and come through it more easily.