ISSN 1866-8836
Клеточная терапия и трансплантация

MP-07. Effectiveness of post-transplant cyclophosphamide in children and adolescents with chronic myeloid leukemia after allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning regimens

Polina V. Sheveleva, Elena V. Morozova, Anna A. Osipova, Olesya V. Paina, Olga A. Slesarchuk, Kirill A. Ekushov, Tatyana L. Gindina, Nikolay N. Mamaev, Ekaterina A. Izmailova, Ildar M. Barkhatov, Tatyana A. Bykova, Elena V. Semenova, Alexander D. Kulagin, Ludmila S. Zubarovskaya

RM Gorbacheva Research Institute, Pavlov University, St. Petersburg, Russia


Contact: Dr. Polina V. Sheveleva, e-mail: sheveleva_p@list.ru

doi 10.18620/ctt-1866-8836-2023-12-3-1-176

Summary

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative method for chronic myeloid leukemia (CML) resistant to tyrosine kinase inhibitors (TKIs). Despite long history, the administration of conditioning regimens depending on the intensity of doses and the prevention of graft-versus-host disease (GvHD) still represents an important issue. The aim of study to was to evaluate the efficacy of reduced-intensity conditioning regimen (RIC) with post-transplant cyclophosphamide (PTCY) to reduce transplant-related complications and mortality in children and adolescent with CML.

Patients and methods

Sixteen patients (pts) had a failure to treatment with TKIs and received allo-HSCT at the RM Gorbacheva Research Institute between 2008 to 2022. The median age at allo-HSCT was 16 years. Median time from diagnosis to allo-HSCT was 34 (5-188) months. At the moment of allo-HSCT, 6 pts were in chronic phase (CP1, 5; CP2, 1 case), 7 pts in accelerated phase (AP), and 3 pts in lymphoid blast crisis. Indications for allo-HSCT in CP and AP were as follows: lacking or lost molecular response (MR) and/or cytogenetic response (CyR) in 7 patients, disease progression to advanced phase (n=3), T315I mutation (n=3). RIC regimen consisted of busulfan 8-10 mg/kg + fludarabine 150-180 mg/m2 (n=13, 82%), or mеlphalan 140 mg/m2 + fludarabine 150-180 mg/m2 (n=2, 12%). The myeloablative conditioning regime (MAC) consisted of busulfan (16 mg/kg) with cyclophosphamide (120 mg/kg) used in 1 case (6 %). Matched related donor was used in 4 pts, matched unrelated donor (UD), in 7 pts; mismatched UD, in 4 pts, haploidentical donor, in 1 case. GvHD prophylaxis consisted of PTCY in 10 pts (63%), anti-thymocyte globulin in 6 pts (37%). Bone marrow (n=7) or peripheral blood cells (n=9) were used as stem cell source; median number of injected CD34+ cells was 3 (1.8 to 8.8), or 6.8 (5.0 to 13.6) ×106/kg weight of the recipient, respectively.

Results

Fourteen patients (87%) achieved engraftment with a median of 19 days (11 to 27); 14 of them achieved сomplete hematologic response and cytogenetic remission; 10 pts achieved complete molecular remission (CMR) оn day +100. Two patients received second allo-HSCT due to graft failure, and one of them received third allo-HSCT. Grade III–IV acute GvHD was registered in 20% (n=2) of cases in PTCy group and 33% (n=2) in ATG. Severe chronic GvHD was registered only in ATG-treated group (n=3; 50%), and was not documented in PTCY group. Four pts (25%) relapsed after allo-HSCT. Among them, one pt with hematologic relapse received chemotherapy + second-generation TKIs, 3 pts with molecular relapse underwent donor lymphocyte infusions + 2G-TKIs thus resulting into CMR. Four pts died due to the following reasons: grade IV aGvHD in one pt with MAC, severe сGvHD (n=1), severe infection (n=1) after third allo-HSCT, and disease progression (n=1). OS after allo-HSCT was 75 % with a median follow-up of 55 months.

Conclusions

Allo-HSCT with RIC and PTCy is an effective and relatively safe therapeutic option in children and adolescents with TKI-resistance CML.

Keywords

Chronic myeloid leukemia, allo-HSCT, children, adolescents, reduced-intensity conditioning.


Supplement 12-3
09/30/2023

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doi 10.18620/ctt-1866-8836-2023-12-3-1-176

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