Immunosuppressive therapy for patients with myelodysplastic syndrome: a prospective randomized multicenter phase III trial comparing antithymocyte globulin plus cyclosporine with best supportive care--SAKK 33/99.

PURPOSE

Immunosuppressive treatment is reported to improve cytopenia in some patients with myelodysplastic syndrome (MDS). Combined antithymocyte globulin (ATG) and cyclosporine (CSA) is most effective in patients with immune-mediated marrow failure.

PATIENTS AND METHODS

This trial was designed to assess the impact of immunosuppression on hematopoiesis, transfusion requirements, transformation, and survival in patients with MDS randomly assigned to 15 mg/kg of horse ATG for 5 days and oral CSA for 180 days (ATG+CSA) or best supportive care (BSC), stratified by treatment center and International Prognostic Scoring System (IPSS) risk score. Primary end point was best hematologic response at 6 months. Eligible patients had an Eastern Cooperative Oncology Group performance status of ≤ 2 and transfusion dependency of less than 2 years in duration.

RESULTS

Between 2000 and 2006, 45 patients received ATG+CSA (median age, 62 years; range, 23 to 75 years; 56% men) and 43 patients received BSC (median age, 65 years; range, 24 to 76 years; 81% men). IPSS score was low, intermediate-1, intermediate-2, high, and not evaluable in eight, 24, seven, one, and five patients on ATG+CSA, respectively, and eight, 25, five, zero, and five patients on BSC, respectively. Refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess of blasts (RAEB) -I, RAEB-II, and hypoplastic disease were present in 21, six, nine, zero, and nine patients on ATG+CSA, respectively, and 18, eight, 11, two, and four patients on BSC, respectively. By month 6, 13 of 45 patients on ATG+CSA had a hematologic response compared with four of 43 patients on BSC (P = .0156). Two-year transformation-free survival (TFS) rates were 46% (95% CI, 28% to 62%) and 55% (95% CI, 34% to 70%) for ATG+CSA and BSC patients, respectively (P = .730), whereas overall survival (OS) estimates were 49% (95% CI, 31% to 66%) and 63% (95% CI, 42% to 78%), respectively (P = .828).

CONCLUSION

This open-label randomized phase III trial demonstrates that ATG+CSA treatment seems to be associated with hematologic response in a subset of patients without apparent impact on TFS and OS.