Treatment Outcomes of Adolescents Compared to Younger Pediatric Patients with Acute Myeloid Leukemia: Do They Need a Special Approach?

BACKGROUND: The reports of studies that compare the survival of adolescents and young adults with younger children with acute myeloid leukemia (AML) are contradictory. PATIENTS AND METHODS: We retrospectively analyzed 220 AML patients aged 0-18 years treated in pediatric oncologic centers in Poland from 2015 to 2022. The evaluated group included 31 infants (below 1 year), 91 younger children (1-9.9 years), 59 older children (10-14.9 years), and 39 adolescents (15-18 years). RESULTS: A 5-year overall survival for adolescents was not significantly inferior compared to younger and older children (74.3 ± 7.6% vs. 80.5 ± 4.4% vs. 77.9 ± 5.1, p = 0.243). However, relapse-free survival was lower in adolescents compared to younger children (76.5 ± 7.8% vs. 65.7 ± 9.0%, p = 0.049), and treatment-related mortality tended to be higher (10.3% vs. 4.4%, p = 0.569). In the univariate analysis, high-risk genetics [HR, 2.0 (95% CI 1.1-3.6; p = 0.014)] and a leukocyte count at diagnosis above 100,000/µL [HR, 2.4 (95% CI 1.3-4.6; p = 0.004)] were found to be unfavorable prognostic factors for survival. CONCLUSIONS: Although we have not found that age over 15 years is an unfavorable factor for overall survival, the optimal approach to therapy in adolescents, as in other age groups, is to adjust the intensity of therapy to individual genetic risk and introduce targeted therapies when indicated.

Pediatric Acute Myeloid Leukemia Post Cytotoxic Therapy-Retrospective Analysis of the Patients Treated in Poland from 2005 to 2022.

Acute P./myeloid leukemia post cytotoxic therapy (AML-pCT) is rare complication of cancer treatment in childhood. The objective of the study was to identify clinical characteristics and provide an analysis of the outcomes in pediatric AML-pCT. We retrospectively analyzed the data of 40 children with AML-pCT, treated from 2005 to 2020 within the Polish Pediatric Leukemia and Lymphoma Study Group. The most common primary malignancies were acute lymphoblastic leukemia (32.5%) and brain tumors (20%). The median latency period was 2.9 years (range: 0.7-12.9). Probabilities of overall (OS), event-free (EFS), and relapse-free survival (RFS) in the whole cohort were 0.49 ± 0.08, 0.43 ± 0.08, and 0.64 ± 0.10, respectively. Significant improvements in outcomes were observed in patients treated from 2015-2022 (two induction cycles followed by stem cell transplantation-SCT in 69% of patients) compared to 2005-2014 (four induction cycles followed by SCT in 49% of patients). The probability of EFS increased from 0.30 ± 0.10 to 0.67 ± 0.12 (p = 0.07) and RFS increased from 0.46 ± 0.11 to 1.0 (p = 0.01). The poorest outcome (OS and EFS 0.25 ± 0.20) was in AML post brain tumor, mainly due to deaths from toxicities. To conclude, treatment results achieved in patients with AML-pCT treated from 2015-2022, with two induction cycles followed by immediate SCT, were better than those reported by other authors, and comparable to the results in de novo AML.

Gemtuzumab ozogamicin for relapsed or primary refractory acute myeloid leukemia in children-the Polish Pediatric Leukemia and Lymphoma Study Group experience.

Background: Gemtuzumab ozogamicin (GO), one of the first targeted drugs used in oncology, consists of an anti-cluster of differentiation 33 (CD33) monoclonal antibody bound to a derivative of cytotoxic calicheamicin. After the drug withdrawn in 2010 due to a significantly higher rate of early deaths, GO regained approval in 2017 for the treatment of newly diagnosed, refractory, or relapsed acute myeloid leukemia (AML) in adults and children over 15 years of age. The objective of the study was a retrospective analysis of clinical characteristics, treatment outcomes, and GO toxicity profile in children with primary refractory or relapsed (R/R) AML treated in Poland from 2008 to 2022. Methods: Data were collected through the Polish Registry of Acute Myeloid Leukemia. From January 2008 to December 2022, 35 children with R/R AML were treated with GO in seven centers of the Polish Pediatric Leukemia and Lymphoma Study Group. Results: Most of the children (30 of 35) received only one GO cycle in combination with various chemotherapy cycles (IDA-FLA, DOXO-FLA, FLA, FLAG, and others). Eighteen children (51%) achieved complete remission (CR), 14 did not respond to treatment, and three progressed. GO therapy was followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) in 18 children in CR. The 5-year overall survival (OS) after GO therapy was 37.1% ± 8.7% for the total cohort. There was a trend toward a superior outcome in patients with strong expression of CD33 expression (over 50% positive cells) compared with that in patients with lower expression of CD33 (OS, 41.2% ± 11.9% versus 27.8% ± 13.2%; p = 0.5; 5-year event-free survival, 35.4% ± 11.6% versus 25.7% ± 12.3%; p = 0.5, respectively). Children under 15 years have better outcome (OS, 34.9% ± 10.4% versus 30% ± 14.5%, p = 0.3). The most common adverse events were bone marrow aplasia, fever of unknown origin, infections, and elevated liver enzyme elevation. Sinusoidal obstruction syndrome occurred in two children. Conclusions: The use of GO in severely pretreated children, including those under 15 years of age, with previous failure of AML treatment is a feasible and effective bridging therapy to allo-HSCT with an acceptable toxicity profile.

Advances in the First Line Treatment of Pediatric Acute Myeloid Leukemia in the Polish Pediatric Leukemia and Lymphoma Study Group from 1983 to 2019.

BACKGROUND: From 1983, standardized therapeutic protocols for pediatric acute myeloid leukemia (AML) based on the BFM group experience were introduced in Poland. We retrospectively analyzed the results of pediatric AML treatment in Poland from 1983 to 2019 (excluding promyelocytic, therapy-related, biphenotypic, and Down syndrome AML). METHODS: The study included 899 children suffering from AML treated with the following: AML-PPPLBC 83 (1983-1993, n = 187), AML-PPGLBC 94 (1994-1997, n = 74), AML-PPGLBC 98 (1998-2004, n = 151), AML-BFM 2004 Interim (2004-2015, n = 356), and AML-BFM 2012 (2015-2019, n = 131). RESULTS: The probability of three-year overall survival was 0.34 ± 0.03, 0.37 ± 0.05, 0.54 ± 0.04, 0.67 ± 0.03, and 0.75 ± 0.05; event-free survival was 0.31 ± 0.03, 0.34 ± 0.05, 0.44 ± 0.04, 0.53 ± 0.03, and 0.67 ± 0.05; and relapse-free survival was 0.52 ± 0.03, 0.65 ± 0.05, 0.58 ± 0.04, 0.66 ± 0.03, and 0.78 ± 0.05, respectively, in the subsequent periods. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients treated with AML-BFM 2012 with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24), while unsatisfactory outcomes were found in the patients with FLT3-ITD. CONCLUSIONS: The use of standardized, systematically modified therapeutic protocols, with the successive consideration of genetic prognostic factors, and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.