IC-01. Post-transplant сyclophosphamide versus conventional GVHD prophylaxis in unrelated donor hematopoietic stem cell transplantation in children with acute myeloid leukemia
Anastasia S. Borovkova, Olesia V. Paina, Zhemal Z. Rakhmanova, Polina V. Kozhokar, Anastasiia S. Frolova, Lubov A. Tsvetkova, Svetlana V. Razumova, Kirill A. Ekushov, Inna V. Markova, Anna A. Osipova, Tatiana A. Bykova, Elena V. Babenko, Alexandr L. Alyanskiy, Ildar M. Barkhatov, Elena V. Semenova, Alexander D. Kulagin, Ivan S. Moiseev, Ludmila L. Zubarovskaya
RM Gorbacheva Research Institute, Pavlov University, St. Petersburg, Russia
Correspondence:
Dr. Anastasia S. Borovkova, phone: +7 (921) 982-22-08, e-mail: bonastasya@mail.ru
Summary
Use of post-transplantation cyclophosphamide (PTCy) with or without additional immunosuppression has been shown to be effective prophylaxis against GVHD following different types of HSCT in adults with hematological malignancies. However, there are limited reports on allo-HSCT with PTCy in children. The aim of the study was to compare efficacy of unrelated HSCT with PTCy and conventional ATG-based GVHD prophylaxis in children with AML.
Patients and methods
We have retrospectively evaluated outcomes in 90 cases of first allogeneic HSCT from matched (n=68), or 9/10 mismatched (n=22) unrelated donors performed by the CIC725 team for children with AML. PTCy was used in 33 patients (37%), and ATG-based GVHD prophylaxis regimens was performed in 57 patients (63%). We excluded those pts who received combination of PTCy and ATG. The median patient age was comparable between PTCy-group and control group (8.8 y.o vs 8.4 y.o., p=0.779). The disease status pre-transplant in PTCy- versus ATG-treated patients was as follows: 1st complete remission (CR1), in 21 (63.6%) and 23 cases (40.4%); CR2, in 5 (15.2%) and 16 cases (28.1%); advanced disease (non-CR1/CR2), in 7 (21.2%) and 18 patients (31.5%, p=0.111). Ratios of MMUD donors were similar in the groups (24.5% vs 24.56%). Bone marrow served as the stem cell source in 40 patients (44%); PBSC, in 50 (56%), p=0.106. Myeloablative conditioning (MAC) was used in 57.7% of total, and its usage was comparable between the study groups (p=0.384).
Results
Cumulative probability of engraftment on day +42, time to neutrophils and platelet engraftment were similar between groups: 90.9% (95%CI 72.0-97.3%) vs 84.2% (95% CI 71.3%-91.7%), p=0.277; 21 (19-25) days vs 17 (14-19) days (p=0.277); 20 (18-25) days vs 17 (14-20) days, p=0.5, respectively. OS rate was higher in PTCy-group: 68.4% (95% CI 48.9%-81.8%) vs 40.1% (95%CI 27.4%-52.5%), p=0.01, with median follow-up of 79 months (31-225). There was no difference for the 2-year EFS, 2-year relapse incidence between the study cohorts: 60.6% (95%CI 42%-74.9%) vs 45.5% (95%CI 32.4%-57.9%), p=0.119; 33% (95%CI 17.9%-49.6%) vs 19.3% (95%CI 10.2%-30.5%), p=0.193. The incidence of grade II-IV aGVHD, III-IV aGVHD at day 125, moderate-severe cGVHD incidence at 3 years, 2-year NRM rates were significantly lower in PTCy-group: 19.7% (95%CI 7.8-35.5%) vs 62% (95%CI 46.1-74.4%), with p<0.001; 9.8% (95CI% 2.4-23.4%) vs 40.6 (95%CI 26.4-54.3%), p=0.004; 25.2% (95%CI 9.7%-44.2%) vs 71.7% (95%CI 50-85.3%), p<0.001; 6.1% (95%CI 1-17.9%) vs 35.1% (95%CI 22.9-47.5%), p=0.002, respectively.
Conclusion
The use of PTCy in children with AML receiving HSCT from MUD/MMUD is a promising option. If compared to ATG prophylaxis, PTCy shows better aGVHD and cGVHD control, lower non-relapse mortality and OS benefit, without increasing primary graft failure and relapse risk.
Keywords
Acute myeloid leukemia, children, allogeneic hematopoietic stem cell transplantation, post-transplant cyclophosphamide, efficiency.
