Trial Information

A Randomized Trial of Antithymocyte Globulin Versus Cyclosporine to Treat the Cytopenia of Myelodysplastic Syndrome

Approximately 40% of the patients with myelodysplastic syndrome (MDS) die as a consequence
of their cytopenia. As in aplastic anemia, the cytopenia of MDS may be partly due to
cytotoxic T cell activity. Immunosuppressive therapy may therefore reverse the cytopenia.
In a phase II pilot study of anti-thymocyte globulin (ATG) to treat myelodysplastic syndrome
(MDS); 41% of patients (61% of patients with refractory anemia) have responded in terms of
transfusion independence. Recently, Jonasova et al [32] reported a 82% substantial
hematological response rate in 18 patients with MDS of the refractory anemia (RA) subtype
treated with cyclosporine alone. Just over 50% of the patients in this series had MDS of
the hypocellular type. Cyclosporine alone if indeed efficacious would be a powerful
therapeutic option that could be readily used by hematologists in the community to treat
patients with MDS. This efficacy needs to be proven in a larger study which includes
patients with the other subtypes of MDS and more patients with the non-hypocellular forms of
MDS (which constitute approximately 70% of the cases in the community). As MDS is a
heterogeneous group of disorders, a randomized comparison with the other immunomodulating
intervention of proven benefit, ATG, is appropriate. In this randomized study patients with
MDS will receive either ATG alone or cyclosporine alone.