Pathologic, cytogenetic, and molecular features of acute myeloid leukemia with megakaryocytic differentiation: A report from the Children's Oncology Group.

2023

e30251

02/2023

1545-5017

BACKGROUND: Acute myeloid leukemia (AML) with megakaryocytic differentiation (AMkL) is a rare subtype of AML more common in children. Recent literature has identified multiple fusions associated with this type of leukemia.

METHODS: Morphology, cytogenetics, and genomic sequencing were assessed in patients from Children's Oncology Group trials AAML0531 and AAML1031 with central-pathology review confirmed non-Down syndrome AMkL. The 5-year event-free survival (EFS), overall survival (OS), and RR were evaluated in these AMkL subcategories.

RESULTS: A total of 107 cases of AMkL (5.5%) were included. Distinct fusions were identified in the majority: RBM15::MRTFA (20%), CBFA2T3::GLIS2 (16%), NUP98 (10%), KMT2A (7%), TEC::MLLT10 (2%), MECOM (1%), and FUS::ERG (1%); many of the remaining cases were classified as AMkL with (other) myelodysplasia-related changes (MRC). Very few cases had AML-associated somatic mutations. Cases with CBFA2T3::GLIS2 were enriched in trisomy 3 (p = .015) and the RAM phenotype, with associated high CD56 expression (p < .001). Cases with NUP98 fusions were enriched in trisomy 6 (p < .001), monosomy 13/del(13q) (p < .001), trisomy 21 (p = .026), and/or complex karyotypes (p = .026). While different 5-year EFS and OS were observed in AMkL in each trial, in general, those with CBFA2T3::GLIS2 or KMT2A rearrangements had worse outcomes compared to other AMkL, while those with RBM15::MRTFA or classified as AMkl-MRC fared better. AMkL with NUP98 fusions also had poor outcomes in the AAML1031 trial.

CONCLUSION: Given the differences in outcomes, AMkL classification by fusions, cytogenetics, and morphology may be warranted to help in risk stratification and therapeutic options.

10.1002/pbc.30251

Pediatr Blood Cancer

36789545

Acute erythroid leukemia is enriched in NUP98 fusions: a report from the Children's Oncology Group.

2020

6000-6008

2020 Dec 08

2473-9537

<p>Acute erythroid leukemia (AEL) is a rare subtype of acute myeloid leukemia (AML) primarily affecting older adults and was previously classified into erythroid/myeloid and pure erythroid subtypes. In this pediatric AEL study, we evaluated morphologic, immunophenotypic, cytogenetic, molecular, and clinical data of 24 (1.2%) cases from all cases undergoing central pathology review in Children's Oncology Group trials AAML0531 and AAML1031. Of 24 cases, 5 had a pure erythroid phenotype, and 19 had an erythroid/myeloid phenotype. NUP98 fusions were highly enriched in patients with AEL, occurring in 7 of 22 cases for which molecular data were available (31.8% vs 6.7% in other AML subtypes). Of 5 cases of pure erythroid leukemias (PELs), 3 had NUP98 fusions, and 4 had complex karyotypes. Erythroid/myeloid leukemias were reclassified by using the 2017 World Health Organization hematopathology classification as: myelodysplastic syndrome (MDS) with excess blasts-1 (n = 3), MDS with excess blasts-2 (n = 7), AML (nonerythroid, n = 5), and unknown MDS/AML (n = 4); the 5 cases of nonerythroid AML included 1 with an NUP98-NSD1 fusion, 2 with myelodysplasia-related changes, and 1 with a complex karyotype. Three cases of MDS with excess blasts-2 also had NUP98 rearrangements. WT1 mutations were present in 5 of 14 cases, all erythroid/myeloid leukemia. Outcomes assessment revealed statistically poorer overall survival (5-year, 20% ± 36% vs 66% ± 23%; P = .004) and event-free survival (5-year, 20% ± 36% vs 46% ± 23%; P = .019) for those with PEL than those with erythroid/myeloid leukemia. Our study supports that AEL is a morphologically and genetically heterogeneous entity that is enriched in NUP98 fusions, with the pure erythroid subtype associated with particularly adverse outcomes.</p>

10.1182/bloodadvances.2020002712

Blood Adv

33284945

Phase I/II Study of CPX-351 Followed by Fludarabine, Cytarabine, and Granulocyte-Colony Stimulating Factor for Children With Relapsed Acute Myeloid Leukemia: A Report From the Children's Oncology Group.

2020

JCO1903306

2020 May 13

1527-7755

<p><strong>PURPOSE: </strong>Effective regimens are needed for children with relapsed acute myeloid leukemia (AML). AAML1421 is a phase I/II study of CPX-351, a liposomal preparation of daunorubicin and cytarabine. AAML1421 sought to determine the recommended phase II dose (RP2D) of CPX-351 and the response rate after up to 2 cycles of therapy.</p>

<p><strong>PATIENTS AND METHODS: </strong>Children &gt; 1 and ≤ 21 years of age with relapsed/refractory AML were eligible for dose finding; those in first relapse were eligible for the efficacy phase. Dose-limiting toxicity (DLT) assessment occurred during cycle 1. Two cycles of therapy were offered (cycle 1: CPX-351; cycle 2: FLAG [fludarabine 30 mg/m/dose on days 1-5; cytarabine 2,000 mg/m/dose on days 1-5; and granulocyte-colony stimulating factor 5 µg/kg/dose, days 1-5 and day 15 through absolute neutrophil count &gt; 500/µL]). Response was assessed after each cycle.</p>

<p><strong>RESULTS: </strong>Thirty-eight patients enrolled: 6 in the dose-finding phase and 32 in the efficacy phase. During dose finding, 1/6 patients experienced a DLT (grade 3 decrease in ejection fraction). The RP2D was 135 units/m on days 1, 3, and 5. Toxicities of grade ≥ 3 during cycle 1 included fever/neutropenia (45%), infection (47%), and rash (40%). There was no toxic mortality. Best responses included 20 complete response (CR; 54%), 5 CR with partial recovery of platelet count (CRp; 14%), and 5 CR with incomplete blood count recovery (14%). Twenty-one of 25 with CR/CRp had no detectable residual disease (RD; 84%) by flow cytometry. Hematopoietic stem cell transplantation (HSCT) was used as consolidation in 29/30 responders (96.7%); 20/25 (80%) had no RD before HSCT.</p>

<p><strong>CONCLUSION: </strong>The RP2D of CPX-351 is 135 units/m/dose on days 1, 3, and 5. Toxicity was manageable, and protocol therapy was effective. Response rates are superior to prior published North American cooperative group clinical trials for children with AML in first relapse.</p>

10.1200/JCO.19.03306

J. Clin. Oncol.

32401633

Functional Properties of KIT Mutations are Associated with Differential Clinical Outcomes and Response to Targeted Therapeutics in CBF Acute Myeloid Leukemia.

2019

2019 Jun 10

1078-0432

<p><strong>PURPOSE: </strong> mutations (+) are common in core binding factor (CBF) AML and have been associated with varying prognostic significance. We sought to define the functional and clinical significance of distinct mutations in CBF pediatric AML.</p>

<p><strong>EXPERIMENTAL DESIGN: </strong>Following transfection of exon 17 (E17) and exon 8 (E8) mutations into HEK293 and Ba/F3 cells, KIT phosphorylation, cytokine independent growth, and response to tyrosine kinase inhibitors (TKI) were evaluated. Clinical outcomes of patients treated on COG AAML0531 (NCT01407757), a phase III study of gemtuzumab ozogamicin (GO), were analyzed according to mutation status (+ vs wild type (-)) and mutation location (E8 vs. E17).</p>

<p><strong>RESULTS: </strong> mutations were detected in 63/205(31%) patients; 22 (35%) involved only E8, 32(51%) only E17, 6(10%) both exons, and 3(5%) alternative exons. Functional studies demonstrated that E17, but not E8, mutations result in aberrant KIT phosphorylation and growth. TKI exposure significantly impacted growth of E17, but not E8, transfected cells. + CBF AML patients had comparable overall survival (OS) to that of - (78%, vs. 81%, p=0.905) but higher relapse rates (RR 43% vs. 21%, p=0.005). E17 + outcomes were inferior to patients [disease free survival (DFS) 51% vs. 73%, p=0.027; RR 21% vs. 46%, p=0.007)] although GO abrogated this negative prognostic impact. E8 mutations lacked significant prognostic impact and GO failed to significantly improve outcome.</p>

<p><strong>CONCLUSIONS: </strong>E17 mutations impact prognosis in CBF AML, as well as response to GO and TKIs, thus clinical trials utilizing both agents should be considered for + patients.</p>

10.1158/1078-0432.CCR-18-1897

Clin. Cancer Res.

31182436

ABCB1 SNP predicts outcome in patients with acute myeloid leukemia treated with Gemtuzumab ozogamicin: a report from Children's Oncology Group AAML0531 Trial.

2019

51

2019 May 21

2044-5385

<p>Gemtuzumab-ozogamicin (GO), a humanized-anti-CD33 antibody linked with the toxin-calicheamicin-γ is a reemerging and promising drug for AML. Calicheamicin a key element of GO, induces DNA-damage and cell-death once the linked CD33-antibody facilitates its uptake. Calicheamicin efflux by the drug-transporter PgP-1 have been implicated in GO response thus in this study, we evaluated impact of ABCB1-SNPs on GO response. Genomic-DNA samples from 942 patients randomized to receive standard therapy with or without addition of GO (COG-AAML0531) were genotyped for ABCB1-SNPs. Our most interesting results show that for rs1045642, patients with minor-T-allele (CT/TT) had better outcome as compared to patients with CC genotype in GO-arm (Event-free survival-EFS: p = 0.022; and risk of relapse-RR, p = 0.007). In contrast, no difference between genotypes was observed for any of the clinical endpoints within No-GO arm (all p &gt; 0.05). Consistent results were obtained when genotype groups were compared by GO and No-GO arms. The in vitro evaluation using HL60-cells further demonstrated consistent impact of rs1045642-T-allele on calicheamicin induced DNA-damage and cell-viability. Our results show the significance of ABCB1 SNPs on GO response in AML and warrants the need to investigate this in other cohorts. Once validated, ABCB1-SNPs in conjunction with CD33-SNPs can open up opportunities to personalize GO-therapy.</p>

10.1038/s41408-019-0211-y

Blood Cancer J

31113932

Gemtuzumab ozogamicin in infants with AML: results from the Children's Oncology Group trials, AAML03P1 and AAML0531.

2017

2017 Jul 03

1528-0020

10.1182/blood-2017-01-762336

Blood

28674028

CD33 Splicing Polymorphism Determines Gemtuzumab Ozogamicin Response in De Novo Acute Myeloid Leukemia: Report From Randomized Phase III Children's Oncology Group Trial AAML0531.

2017

JCO2016712513

2017 Jun 23

1527-7755

<p>Purpose Gemtuzumab ozogamicin (GO), a CD33-targeted immunoconjugate, is a re-emerging therapy for acute myeloid leukemia (AML). CD33 single nucleotide polymorphism rs12459419 C&gt;T in the splice enhancer region regulates the expression of an alternatively spliced CD33 isoform lacking exon2 (D2-CD33), thus eliminating the CD33 IgV domain, which is the antibody-binding site for GO, as well as diagnostic immunophenotypic panels. We aimed to determine the impact of the genotype of this splicing polymorphism in patients with AML treated with GO-containing chemotherapy. Patients and Methods CD33 splicing single nucleotide polymorphism was evaluated in newly diagnosed patients with AML randomly assigned to receive standard five-course chemotherapy alone (No-GO arm, n = 408) or chemotherapy with the addition of two doses of GO once during induction and once during intensification (GO arm, n = 408) as per the Children's Oncology Group AAML0531 trial. Results The rs12459419 genotype was CC in 415 patients (51%), CT in 316 patients (39%), and TT in 85 patients (10%), with a minor allele frequency of 30%. The T allele was significantly associated with higher levels of D2-CD33 transcript ( P &lt; 1.0E(-6)) and with lower diagnostic leukemic cell surface CD33 intensity ( P &lt; 1.0E(-6)). Patients with the CC genotype had significantly lower relapse risk in the GO arm than in the No-GO arm (26% v 49%; P &lt; .001). However, in patients with the CT or TT genotype, exposure to GO did not influence relapse risk (39% v 40%; P = .85). Disease-free survival was higher in patients with the CC genotype in the GO arm than in the No-GO arm (65% v 46%, respectively; P = .004), but this benefit of GO addition was not seen in patients with the CT or TT genotype. Conclusion Our results suggest that patients with the CC genotype for rs12459419 have a substantial response to GO, making this a potential biomarker for the selection of patients with a likelihood of significant response to GO.</p>

10.1200/JCO.2016.71.2513

J. Clin. Oncol.

28644774

Disease Characteristics and Prognostic Implications of Cell Surface FLT3 Receptor (CD135) Expression in Pediatric Acute Myeloid Leukemia: A Report from the Children's Oncology Group.

2017

2017 Jan 20

1078-0432

<p><strong>PURPOSE: </strong>The FLT3 cell-surface receptor tyrosine kinase (CD135) is expressed in a majority of both acute lymphoid leukemia (ALL) and myeloid leukemia (AML). However, the prognostic significance of CD135 expression in AML remains unclear. We therefore evaluated the association between FLT3 surface expression and disease characteristics and outcomes in pediatric patients with AML.</p>

<p><strong>EXPERIMENTAL DESIGN: </strong>We analyzed FLT3 receptor expression on AML blasts by multi-dimensional flow cytometry and its association with disease characteristics, clinical outcomes, and FLT3 transcript level in 367 children with AML treated on the Children's Oncology Group trial AAML0531.</p>

<p><strong>RESULTS: </strong>There was high variability in blast CD135 cell-surface expression across specimens. CD135 expression measure by flow cytometry was not correlated with FLT3 transcript expression determined by quantitative RT-PCR. Overall, CD135 expression was not significantly different for patients with FLT3/WT and those with FLT3/ITD and FLT3/ALM (p=0.25). High cell-surface CD135 expression was associated with FAB M5 subtype (p&lt;0.001), KMT2A rearrangements (p=0.009) and inversely associated with inv(16)/t(16;16) (p&lt; 0.001). Complete remission rate, overall survival, disease-free survival, and relapse rates were not significantly different between patients with low and high CD135 expression.</p>

<p><strong>CONCLUSIONS: </strong>FLT3 cell-surface expression did not vary by FLT3 mutational status, but high FLT3 expression was strongly associated with KMT2A rearrangements. Our study found that there was no prognostic significance of FLT3 expression in pediatric AML.</p>

10.1158/1078-0432.CCR-16-2353

Clin. Cancer Res.

28108543

Gemtuzumab Ozogamicin Reduces Relapse Risk in FLT3/ITD Acute Myeloid Leukemia: A Report from the Children's Oncology Group.

2015

2015 Dec 7

1078-0432

<p><strong>PURPOSE: </strong>Gemtuzumab ozogamicin (GO), a calicheamicin-conjugated mAb against CD33, has been used in the treatment of acute myeloid leukemia (AML). We evaluated the impact of the addition of GO to standard chemotherapy and hematopoietic stem cell transplant (HCT) in patients with FLT3/ITD.</p>

<p><strong>EXPERIMENTAL DESIGN: </strong>We analyzed children with FLT3/ITD-positive AML (n = 183) treated on two consecutive Children's Oncology Group AML trials (NCT00070174 and NCT00372593). Outcomes were assessed for FLT3/ITD patients receiving standard chemotherapy with or without GO (GO vs. No-GO, respectively), and the impact of consolidation HCT for high-risk FLT3/ITD patients [high FLT3/ITD allelic ratio (ITD-AR)].</p>

<p><strong>RESULTS: </strong>For all FLT3/ITD patients, complete remission (CR) rates for the GO versus No-GO cohorts were identical (64% vs. 64%; P = 0.98). Relapse rate (RR) after initial CR was 37% for GO recipients versus 59% for No-GO recipients (P = 0.02), disease-free survival (DFS) was similar (47% vs. 41%; P = 0.45), with higher treatment-related mortality (TRM) in GO recipients (16% vs. 0%; P = 0.008). Among high-risk FLT3/ITD patients with high ITD-AR, those who received HCT in first CR with prior exposure to GO had a significant reduction in RR (15% vs. 53%; P = 0.007), with a corresponding DFS of 65% versus 40% (P = 0.08), and higher TRM (19% vs. 7%; P = 0.08).</p>

<p><strong>CONCLUSIONS: </strong>CD33 targeting with HCT consolidation may be an important therapeutic strategy in high-risk FLT3/ITD AML and its efficacy and associated toxicity warrant further investigation. Clin Cancer Res; 1-7. ©2015 AACR.</p>

10.1158/1078-0432.CCR-15-1349

Clin. Cancer Res.

26644412

CD33 Expression and Its Association With Gemtuzumab Ozogamicin Response: Results From the Randomized Phase III Children's Oncology Group Trial AAML0531.

2016

747-55

2016 Mar 1

1527-7755

<p><strong>PURPOSE: </strong>CD33 is variably expressed on acute myeloid leukemia (AML) blasts and is targeted by gemtuzumab ozogamicin (GO). GO has shown benefit in both adult and pediatric AML trials, yet limited data exist about whether GO response correlates with CD33 expression level.</p>

<p><strong>PATIENTS AND METHODS: </strong>CD33 expression levels were prospectively quantified by multidimensional flow cytometry in 825 patients enrolled in Children's Oncology Group AAML0531 and correlated with response to GO.</p>

<p><strong>RESULTS: </strong>Patients with low CD33 expression (lowest quartile of expression [Q1]) had no benefit with the addition of GO to conventional chemotherapy (relapse risk [RR]: GO 36% v No-GO 34%, P = .731; event-free survival [EFS]: GO 53% v No-GO 58%, P = .456). However, patients with higher CD33 expression (Q2 to Q4) had significantly reduced RR (GO 32% v No-GO 49%, P &lt; .001) and improved EFS (GO 53% v No-GO 41%, P = .005). This differential effect was observed in all risk groups. Specifically, low-risk (LR), intermediate-risk (IR), and high-risk (HR) patients with low CD33 expression had similar outcomes regardless of GO exposure, whereas the addition of GO to conventional chemotherapy resulted in a significant decrease in RR and disease-free survival (DFS) for patients with higher CD33 expression (LR RR, GO 13% v No-GO 35%, P = .001; LR DFS, GO 79% v No-GO 59%, P = .007; IR RR, GO 44% v No-GO 57%, P = .044; IR DFS, GO 51% v No-GO 40%, P = .078; HR RR, GO 40% v No-GO 73%, P = .016; HR DFS, GO 47% v No-GO 28%, P = .135).</p>

<p><strong>CONCLUSION: </strong>We demonstrate that GO lacks clinical benefit in patients with low CD33 expression but significantly reduces RR and improves EFS in patients with high CD33 expression, which suggests a role for CD33-targeted therapeutics in subsets of pediatric AML.</p>

10.1200/JCO.2015.62.6846

J. Clin. Oncol.

26786921