NEW ORLEANS (FRONTLINE MEDICAL NEWS) – Stem cell-mediated functional regeneration continues to attract interest in the treatment of multiple sclerosis (MS). The reality, however, is daunting.

“Several types of cell-based therapeutic strategies are under investigation, with different risks, benefits, and goals. Some of these strategies show promise but significant methodological questions need to be answered,” Dr. Andrew D. Goodmansaid at a meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis.

The present reality is that stem cell transplantation is not yet ready for general use to treat MS. Yet, the possible benefits of the approach demand further exploration, including clinical trials, according to Dr. Goodman, professor of neurology, chief of the neuroimmunology unit, and director of the multiple sclerosis center at the University of Rochester (N.Y.).

MS stem cell therapy hinges on the pluripotent nature of stem cells, particularly mesenchymal stem cells (MSCs) and hematopoietic stem cells. MS therapy would involve regeneration of nerve cell myelin in the brain and/or spinal cord and possibly suppression of inflammation.

Autologous HSC transplantation

Immunoablation followed by the autologous HSC transplantation (HSCT) has been explored in the ASTIMS phase II randomized trials ( Neurology. Mar 10;84[10]:981-8 and HALT-MS, JAMA Neurol. 2015 Feb;72[2]:159-69 ), and in a Northwestern University case series ( JAMA. 2015 Jan 20;313[3]:275-84 ).

ASTIMS compared high-dose chemotherapy followed by autologous HSCT with mitoxantrone (which is no longer used). Only 22% percent of patients had relapsing-remitting MS (RRMS; the one where HSCT generally works) and 78% had primary progressive MS (where HSCT generally does not work well or is not optimal). Yet, HSCT worked, with new T2 lesions reduced by 79%. No difference in disability progression was evident. Interim (3-year) results of HALT-MS were encouraging, with sustained remission of active RRMS and improved neurologic function. The Northwestern case series also documented improvements in neurologic disability and other clinical outcomes.

“The available data suggest that immunoablation and HSCT is highly effective in active RRMS. Patients most likely to benefit are young and still ambulatory with a relatively recent disease onset featuring highly active MS with MRI lesion activity and continued activity despite first- and second-line agents,” Dr. Goodman said.

While encouraging, the small patient numbers of the two trials and uncontrolled nature of the case series prevent conclusions concerning the therapeutic use of autologous HSCT in RRMS. Furthermore, risks of the approach include MS relapse, treatment-related adverse effects, adverse effects due to myelosuppression and immunoablation, and secondary autoimmune disorders that may arise at a later time.

Mesenchymal stem cell transplantation

MSCs offer the advantages of a variety of sources in adult tissue, established methods of culture, and either local or peripheral administration. Their finite capacity for proliferation is a drawback. Studies to date of MSC transplantation in MS have involved about 100 patients, so it is much too early to consider MSC use. Even if therapy is contemplated, whether it should be directed at quelling inflammation or to promote repair is undecided. As well, cell production and delivery issues need to be addressed, Dr. Goodman said.

Human oligodendrocyte progenitor cell transplantation

The implantation of CD 140a+ cell populations containing human oligodendrocyte progenitor cells (hOPCs) into the cerebral hemispheres of patients with non-relapsing secondary progressive MS as a means of stabilizing or improving neurological function is being planned. The NYSTEM project, with Dr. Goodman as a lead investigator, will first seek to identify the maximum tolerated dose of hOPCs.

The study is planned with the knowledge of safety issues that include cancer tumorigenesis. Yet exploration of the possible benefits will be evident only by testing in humans. “I don’t know of any way to find out except by trying,” Dr. Goodman said.

Dr. Goodman disclosed receiving research support and/or serving as a consultant to Avanir, Teva, Genzyme/Sanofi, Sun Pharma, Ono, Roche, AbbVie, Biogen, Novartis, Acorda, Purdue, and EMD Serono.