Stem Cell Transplant Can Produce Long-term Benefits in Relapsing MS Patients

A stem cell transplant can prevent disability progression and maintain disease remission over long periods of time in most patients with relapsing forms of multiple sclerosis (MS) who failed to respond adequately to disease-modifying therapies (DMTs), a study reports.

The study, “Long-Term Clinical Outcomes of Hematopoietic Stem Cell Transplantation in Multiple Sclerosis,” was published in the journal Neurology.

Since the late 1990s, researchers have been exploring the therapeutic potential of autologous hematopoietic stem cell transplant (AHSCT) for MS patients who failed to respond to conventional DMTs.

In an AHSCT, a patient’s healthy blood cell progenitors, also known as hematopoietic stem cells, are collected from the bone marrow before he or she undergoes immunoablation — a procedure in which a combination of chemotherapy agents is used to wipe out the patient’s overactive immune system.

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By partly or fully destroying a patient’s faulty immune system, immunoablation “makes room” for the new, less reactive immune cells that will be derived from the blood cell precursors collected earlier. Once these cells are inserted back into the patient’s body, they can reconstitute the immune system.

Because this procedure allows for a full reset of the body’s immune system, it has the potential to significantly lower disease activity, along with MS relapses.

Despite being promising from a theoretical point of view, the transplant’s long-term effects still need to be studied in these patients.

Now, a group of investigators in Italy have reported the long-term clinical outcomes of a large group of 210 MS patients who had a stem cell transplant between 1997 and 2019.

Patients included in the analyses had a mean age of 35 years, and the majority had been diagnosed with a relapsing form of MS, such as relapsing-remitting MS (RRMS) or active secondary progressive MS, according to a press release from the National Multiple Sclerosis Society. Most of them had also received BEAM+ATG, an intense chemotherapy combination as part of the immunoablation regimen that preceded the transplant itself.

At the study’s start, participants had a mean expanded disability status scale (EDSS) score of 6, corresponding to a moderate-to-high level of disability, in which patients need the help of a cane or crutch to move around.

When re-evaluated a decade after receiving the transplant, more than half (65.5%) of the patients continued showing no signs of disability worsening. These values were even higher (71.3%) in the subset of 122 RRMS patients included in the study.

The levels of disability in this subgroup of patients started to decrease since the transplant, with EDSS scores dropping a mean of 0.09 units per year.

Before 2007, three patients died within a period of 100 days following AHSCT, but after 2007, no patient died within 100 days of having the procedure.

Statistical analyses also found that patients who had immunoablation with BEAM+ATG and those who experienced a higher number of relapses before receiving the transplant, were more likely to show no signs of disability progression 10 years after the procedure.

“The BEAM+ATG conditioning protocol is associated with a more pronounced suppression of clinical relapses and MRI inflammatory activity,” the investigators wrote.

Taken together, the data provide “evidence that for people with MS, AHSCT induces durable disease remission,” the team wrote. Specifically, “aHSCT prevents disability worsening in the majority of patients and induces durable improvement in disability in patients with RRMS.”

These findings are in line with those of previous studies suggesting that a stem cell transplant may be particularly effective for specific groups of patients with active forms of MS who have failed to respond adequately to DMTs.

Based on data from these studies, the National MS Society recently released a set of recommendations on who would be the best candidates for this procedure. According to the experts, patients with relapsing forms of the disease, who are younger than 50, and who continue showing signs of disease activity despite treatment with high-efficacy DMTs, are likely to benefit most from a stem cell transplant.