Stem cell transplantation in rheumatoid arthritis

The therapeutic potential of high dose cytotoxic therapy and stem cell transplantation (SCT) in severe rheumatoid arthritis (RA) was originally supported by animal studies and serendipitous clinical cases where allogeneic and autologous procedures were shown to ameliorate and potentially cure the disease. Phase I and Phase II clinical studies established the feasibility, safety and efficacy of autologous stem cell mobilisation and transplantation. Although it was clear that the effects of high dose chemotherapy and autologous SCT could safely achieve profound responses, sustained control of disease usually required the reintroduction of disease modifying agents. Responses were improved with dose escalation of the conditioning regimen, and also with post-SCT therapy, such as rituximab, but were not observed with graft manipulation. Phase III studies were attempted, but recruitment was compromised by the increasingly widespread use of biological anti-rheumatic agents. Autologous SCT is now only reasonably considered in relatively rare patients whose disease has resisted conventional and biological treatments, and small numbers of cases continue to be registered with the EBMT. Occasional patients treated with allogeneic and syngeneic SCT continue to stimulate academic interest, particularly as some appear to be cured, but significant logistical and toxicity issues mean that routine and widespread application is unrealistic. In summary, SCT continues to have a limited therapeutic potential in rare patients with RA refractory to modern therapy and sufficient fitness for the procedure. From a scientific perspective, ablation of the dysfunctional rheumatoid immune system and its reconstruction with SCT has provided useful insights into the pathophysiology of RA.