Introduction: It is generally known that horse antithymocytic globulin (ATGAM) are more effective for treatment of pts with acquired AA than rabbit ATG. There is no doubt, that dose regime 160 mg/kg ATGAM Improves response for young pts after 1st course. Optimal ATGAM dose is important unsettled issue to achieve as soon as possible remission in adult pts and reduce time to allo-BMT in refractory cases.

Aim of this study is to evaluateeffectiveness and response rate on ATGAM*100 and ATGAM*160 dose in adult pts with AA.

Material and methods: Twenty-eight patients with acquired AA (NSAA/SAA) required in combined IST with ATGAM and cyclosporin A were included into the prospective study. We are presenting a single-center experience. The median of observation time was 29 (3-47) months. All pts were randomized before IST into 2 groups: ATGAM*100 (ATGAM 20 mg/kg/day 1-5 days, n=14) and ATGAM*160 (ATGAM 40 mg/kg/day 1-4 days, n=14). There were no significant differences between two groups in such parameters as: mеdiane age (26 vs 25 years); gender (M/W: 8/6 vs 9/5); severity (NSAA/SAA: 9/5 vs 7/7); median of Grans (0,68 vs 0,51x109/l) and Ret (30,9 vs 17,04x109/l); presence of PNH-clone ( 9 vs 12 pts); median time to the start of IST after diagnosis were 29 vs 24 months respectively.

Results: The frequency of reaction to drug administration, serum sickness and infections complications were comparable in both groups. Cumulative rate of overall response was higher in ATGAM*100 group (86,6 %) vs ATGAM*160 group (76.1 %). The second course of ATGAM*100 were effective in 3 of 4 pts who did not achieve response after 1st course, however, the second course of ATGAM*160 were not effective in 2 of 2 pts. Complete response rate after the first course of ATGAM*160 was 64%, but in group ATGAM*100 it was 36% (p>0,05) even after 2nd course. It is important to note, that median time to achieve response was less in ATGAM*160 (2,7 vs 6,2 months respectively).

Conclusion: In conclusion we propose that Low-dose of ATGAM for treatment of adult AA patients were effective but not sufficient to reduce timing before allo-BMT


No relevant conflicts of interest to declare.

Author notes


Asterisk with author names denotes non-ASH members.

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