Antithymocyte globulin for treatment of the bone marrow failure associated with myelodysplastic syndromes.

BACKGROUND: Almost half of the deaths that result from myelodysplastic syndromes are due to cytopenia associated with bone marrow failure. Treatment is mostly supportive care.

OBJECTIVE: To determine whether treatment with antithymocyte globulin improves cytopenia and reverses dependence on red blood cell transfusions in patients with myelodysplastic syndromes.

DESIGN: Single-treatment, prospective study.

SETTING: Tertiary referral center.

PATIENTS: 61 patients with myelodysplastic syndromes.

INTERVENTION: Antithymocyte globulin, 40 mg/kg of body weight, given daily for 4 days.

MEASUREMENTS: Evaluation of bone marrow, blood counts, transfusions, progression, and survival for a median of 30 months (range, 1 to 88 months).

RESULTS: Within 8 months of treatment, 21 of 61 patients (34%) no longer required red blood cell transfusions. This independence from transfusions was maintained in 17 responders (81%) for a median of 36 months (range, 3 to 72 months). Ten of 21 patients (47.5%) with severe thrombocytopenia had sustained platelet count increases, and 6 of 11 patients (55%) with severe neutropenia had sustained neutrophil counts of greater than 1 x 10(9) cells/L. Characteristics favorable for response were younger patient age (P = 0.005) and lower platelet counts (P = 0.038). One of the 21 responders (5%) and 22 of the 40 nonresponders (55%) died before the end of the study (P = 0.008). One of the 21 responders (5%) and 13 of the 40 nonresponders (33%) had disease progression (P = 0.086).

CONCLUSIONS: Although this study was a nonrandomized, single-treatment study, 34% of patients treated with antithymocyte globulin became transfusion independent. Response was associated with a statistically significant longer survival and an almost significant decreased time to disease progression. Treatment with antithymocyte globulin did not seem to be detrimental because historical overall median survival times were similar to those of nonresponders.