Hematopoietic stem cell transplantation for multiple sclerosis: finding equipoise

[Indications and follow-up for autologous hematopoietic stem cell transplantation in multiple sclerosis: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) in association with the Francophone Society of Multiple Sclerosis]

The Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) organized the 8th allogeneic hematopoietic stem cell transplantation clinical practices harmonization workshop series in September 2017 in Lille, France. In this article we give the indications of autologous stem cell transplantation in multiple sclerosis as well as recommendations regarding post-transplant follow-up of patients under the hospice of the SFGM-TC and the Francophone Society of Multiple Sclerosis.

Hematopoietic stem cell transplantation (HSCT): An approach to autoimmunity

HSCT provides the opportunity to replace a damaged tissue. It is the most important treatment for high risk hematologic malignant and non malignant disorders. An important challenge in the identification of matched donors/patients is the HLA diversity. The Mexican Bone Marrow Registry (DONORMO) has nowadays > 5000 donors. The prevalent alleles are Amerindian, Mediterranean (Semitic and Spanish genes) and African. In theory, it is possible to find 11% of 6/6 A-B-DR low resolution matches for 70% of patients with Mexican ancestry. We contributed with 39 unrelated, cord blood and autologous HSCT for patients with malignant, genetic and autoimmune disorders. Overall disease survival was 50% (2-7 years) depending on the initial diagnosis, conditioning, disease evolution or other factors. Clinical studies using autologous and unrelated HSC are performed on patients with refractory autoimmune diseases producing mixed results: mainly, T1D, RA, MS, SLE. Improvement has been observed in skin damage and quality of life in SLE and systemic sclerosis. Disease stabilization in 2/3 of MS patients. However, in RA and T1D, initial benefits have been followed by eventual relapse. With growing clinical experience and protocol improvement, treatment-related mortality is decreasing. Proof efficacy will be achieved by comparing HSCT with standard therapy in autoimmunity.

High-dose therapy for autoimmune neurologic diseases

PURPOSE OF REVIEW

Autoimmune neurologic diseases are being increasingly recognized, and treated with conventional immunosuppressive agents. Patients with 'refractory' conditions have been treated with high-dose therapy, with or without autologous stem cell transplants. This paper reviews the rationale, methods, and recent results of high-dose therapy and the questions that it raises.

RECENT FINDINGS

High-dose therapy has been used in progressive multiple sclerosis and in myasthenia gravis and autoimmune neuropathies that are refractory to conventional immunotherapy. A variety of methods of immune ablation have been used; most require hematopoietic 'rescue' with stem cell transplantation. High-dose cyclophosphamide alone is immunoablative but not myeloablative, permitting the patient's endogenous stem cells to repopulate the hematopoietic/immune systems. The results have been highly encouraging in many but not all cases, with durable responses in the limited time they have been followed up. The treatments carry some risks and have been reserved for refractory cases until now.

SUMMARY

High-dose therapy, without or with stem cell transplantation, is a valuable resource for the treatment of patients with refractory autoimmune neurologic diseases. It is important to define the diseases and patient characteristics likely to lead to benefit, to optimize the methods of treatment and to establish when in the patient's course to administer it. High-dose therapy may eventually become the standard for treatment of severe progressive autoimmune neurologic disorders.

Stem cell transplantation for autoimmune disorders. Coincidental autoimmune disease in patients transplanted for conventional indications

The practice of stem cell transplantation for severe autoimmune diseases refractory to conventional therapy originated from two landmark discoveries: the excellent results of animal experiments, and serendipitous observations in human coincidental diseases. The latter include patients with an often long-standing autoimmune disease who have developed a haematological condition (aplasia, leukaemia, lymphoma) requiring stem cell transplantation (from marrow as well as from blood). Allogeneic and autologous transplants have been performed. The initial information deriving from both procedures is their feasibility, even more convincing since the patients were affected by two simultaneous severe diseases. The information derived from autologous transplants has, however, now been superseded by the considerable and increasing number of those transplants performed for primary autoimmune diseases. On the other hand, allogeneic stem cell transplantation for very severe autoimmune diseases is being cautiously explored in current protocols. Allogeneic transplants in coincidental disease have also suggested a graft-versus-autoimmunity effect, which may become relevant in conjunction with non-myeloablative, less toxic condition regimens.

Haematopoietic stem cell transplantation for autoimmune disorders: the American perspective

The hypothesis that haematopoietic stem cell transplantation (HSCT) might be useful in treating refractory autoimmune diseases (AID) was suggested by studies in animal models and by the improvement of concurrent autoimmune diseases in patients who had undergone transplantation for haematological disorders. This concept has now been tested in a substantial number of phase I/II clinical trials of autologous HSCT. These early results are promising, even in patients who have failed on multiple standard therapies for AID. Transplantation-related toxicity has decreased with growing experience in the application of this procedure, better patient selection and the modification of treatment protocols. Randomized trials currently under way or under consideration should clarify the role of HSCT in patients with autoimmune disorders.