AL-06. The outcomes of hematopoietic stem cell transplantation in pediatric patients with chemorefractory acute myeloid leukemia
Maria A. Ilyushina, Larisa N. Shelikhova, Daria A. Shasheleva, Elena E. Kurnikova, Yakov O. Muzalevsky, Irina I. Kalinina, Galina A. Novichkova, Aleksey A. Maschan, Michael A. Maschan
Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
Contact: Dr. Maria A. Ilyushina, e-mail: maria.ilushina@gmail.com
Summary
The hematopoietic stem cell transplantation (HSCT) is known to be most efficient for patients in an initial remission. In this research, we analyzed a cohort of children with chemorefractory acute myeloid leukemia (AML) in order to study the efficiency of HSCT in this cohort of patients.
Materials and methods
A total of 69 pts with chemorefractory AML (induction failure (n=32), refractory relapse (n=37), 30 female/39 male, median age 9.4 years (1.1-22), underwent HSCT between Feb 2012 and Jan 2020, at median follow-up of 5.47 years (2-9). 49 pts were transplanted from haploidentical, 12 from matched family donors, 8 from matched unrelated donors. All pts received treosulfan-based conditioning regimen. The following conditioning regimens of GvHD prophylaxis were used: regimen 1 (n=9) included ATGAM 50 mg/kg + Tacro/MTX; regimen 2 (n=11) consisted of: thymoglobulin (5mg/kg), rituximab (200 mg/m2), and bortezomib on day +2,+5 (n=9); regimen 3 (n=36) included tocilizumab (8 mg/kg), and post-transplant bortezomib (n=33). Moreover, 24 pts received additional abatacept at 10 mg/kg on day+2,+7,+14, +28; regimen 4 was performed with post-transplant cyclophosphamide. Ten pts did not receive any prophylaxis. TCRαβ+/CD19+-depletion of stem cells with CliniMACS technology was implemented in 55 cases; 12 patients received native BM. Twenty-one patients received post-transplant therapy by means of hypomethylating agents; 48 pts. Were subjected to modified donor lymphocyte infusions (DLI).
Results
Primary engraftment was achieved in 66 of 69 pts (3 pts died before engraftment), the median time to recovery of ANC and platelets was 14 days (10-49). Complete chimerism by the day +30 was achieved by 85% pts. The cumulative incidence (CI) of grade 2-4 aGvHD was 55%, chronic GvHD, 17%. Serotherapy (ATG) did not affect the incidence of GvHD. Among all patients, transplant-related mortality was 8%, CI of relapse, 52%. The incidence of relapse in a subgroup with CMV reactivation was 47%, in CMV reactivation-free subgroup, 58% (p=0.5). NK-cell recovery at day +30 was significantly associated with decreased incidence of relapse, CI of relapse was 76% in patients with below-median peripheral blood NK recovery, and 43% in those with over-median NK-cell numbers (p=0.013). At a median follow-up of 5,5 years, event-free survival was 37% and overall survival was 42%.
Conclusion
Performing HSCT in patients with refractory AML resulted in a remission in 85% of patients and long-term survival of 40%. Improving early NK cell recovery may open up the opportunity to effectively enhance the anti-tumor effect and decrease the relapse rates in children with chemorefractory AML.
Conflict of interest
The authors do not declare any competing interests.
Keywords
Acute myeloid leukemia, chemorefractory, allogeneic hematopoietic stem cell transplantation, NK-cell, recovery.
