Naghmeh Niktoreh

Therapy-related acute myeloid leukemia (AML; tAML) is one of the most feared therapy-emergent complications. This study aims to determine the clinical and pathological significance and define therapeutic implications and poor prognosticators in pediatric tAML. We analyzed a total of 119 pediatric patients (aged 2-20 years) who were centrally diagnosed with tAML within the Acute Myeloid Leukemia Berlin-Frankfurt-Münster (AML-BFM) study group between 1993 and 2019. Compared with de novo AML, tAML was associated with decreased white blood count and involvement of the central nervous system. Latency to tAML was inversely correlated with age at primary malignancy. Patients with tAML were more likely to have abnormal karyotypes, overrepresenting KMT2A rearrangements, the unfavorable cytogenetics –7/del(7q), as well as complex and monosomal karyotypes, whereas core-binding AML was underrepresented. The occurrence of stratification-relevant molecular genetics was comparable with de novo AML, whereas CEBPAdm was absent in tAML. Survival rates in tAML improved from 10% ± 6% in AML-BFM 1993/1998 to 50% ± 10% in the registries 2012/2017; however, this is still worse than de novo AML. Hematopoietic stem cell transplantation (HSCT) in no evidence of leukemia (NEL; 35 Gy), and latency ≤1 year were identified as the strongest poor prognosticators. Over the past 26 years, outcome and survival significantly improved in pediatric tAML. Our results suggest that HSCT in NEL after 2 induction cycles is the most promising therapeutic approach for achieving improved survival. Radiation, adverse cytogenetics, and latency ≤1 year should be considered as poor prognosticators in pediatric tAML.

WT1 is a true chameleon, both acting as an oncogene and tumor suppressor. As its exact role in leukemogenesis is still ambiguous, research with model systems representing natural conditions surrounding the genetic alterations in WT1 is necessary. In a cohort of 59 leukemia/lymphoma cell lines, we showed aberrant expression for WT1 mRNA, which does not always translate into protein levels. We also analyzed the expression pattern of the four major WT1 protein isoforms in the cell lines and primary AML blasts with/without WT1 mutations and demonstrated that the presence of mutations does not influence these patterns. By introduction of key intronic and exonic sequences of WT1 into a lentiviral expression vector, we developed a unique tool that can stably overexpress the four WT1 isoforms at their naturally occurring tissue-dependent ratio. To develop better cellular model systems for WT1, we sequenced large parts of its gene locus and also other important myeloid risk factor genes and revealed previously unknown alterations. Functionally, inhibition of the nonsense-mediated mRNA decay machinery revealed that under natural conditions, the mutated WT1 alleles go through a robust degradation. These results offer new insights and model systems regarding the characteristics of WT1 in leukemia and lymphoma.

In acute myeloid leukaemia (AML) RUNX1 mutation is characterised by certain clinicopathological features with poor prognosis and adverse risk by the European LeukemiaNet recommendation. Though initially considered as provisional category, the recent World Health Organisation (WHO) classification of 2022 removed RUNX1-mutated AML from the unique entity. However, the significance of RUNX1 mutation in paediatric AML remains unclear. We retrospectively analysed a German cohort of 488 paediatric patients with de novo AML, enroled in the AMLR12 or AMLR17 registry of the AML-BFM Study Group (Essen, Germany). A total of 23 paediatric AML patients (4.7%) harboured RUNX1 mutations, 18 of which (78%) had RUNX1 mutation at initial diagnosis. RUNX1 mutations were associated with older age, male gender, number of coexisting alterations and presence of FLT3-ITD but mutually exclusive of KRAS, KIT and NPM1 mutation. RUNX1 mutations did not prognostically impact overall or event-free survival. Response rates did not differ between patients with and without RUNX1 mutations. This comprehensive study, comprising the largest analysis of RUNX1 mutation in a paediatric cohort to date, reveals distinct but not unique clinicopathologic features, with no prognostic significance of RUNX1-mutated paediatric AML. These results broaden the perspective on the relevance of RUNX1 alterations in leukaemogenesis in AML.

In acute myeloid leukaemia (AML) RUNX1 mutation is characterized by certain clinicopathological features with poor prognosis and adverse risk by the European LeukemiaNet recommendation. Though initially considered as provisional category, the recent World Health Organization (WHO) classification of 2022 removed RUNX1-mutated AML from the unique entity. However, the significance of RUNX1 mutation in paediatric AML remains unclear. We retrospectively analysed a German cohort of 488 paediatric patients with de novo AML, enrolled in the AMLR12 or AMLR17 registry of the AML-BFM Study Group (Essen, Germany). A total of 23 paediatric AML patients (4.7%) harboured RUNX1 mutations, 18 of which (3.7%) had RUNX1 mutation at initial diagnosis. RUNX1 mutations were associated with older age, male gender, number of coexisting alterations and presence of FLT3-ITD but mutually exclusive of KRAS, KIT and NPM1 mutation. RUNX1 mutations did not prognostically impact overall- or event-free survival. Response rates did not differ between patients with and without RUNX1 mutations. This comprehensive study, comprising the largest analysis of RUNX1 mutation in a paediatric cohort to date, reveals distinct but not unique clinicopathologic features, with no prognostic significance of RUNX1-mutated paediatric AML. These results broaden the perspective on the relevance of RUNX1 alterations in leukaemogenesis in AML.

KMT2A rearrangements (KMT2A-r) are among the most common structural aberrations in pediatric acute myeloid leukemia (AML) and are very important for the risk group stratification of patients. Here, we report the outcome of 967 pediatric AML patients with a known KMT2A-r status. The large cohort was characterized by morphology, multicolor flow cytometry, classical cytogenetics and mutation analysis via panel sequencing. In total, the blasts of 241 patients (24.9%) showed KMT2A-r. KMT2A-r is associated with FAB M5, a high white blood cell count and younger age at diagnosis. When subgroups were combined, KMT2A-r had no impact on event-free survival (EFS) and overall survival (OS); however, various subgroups showed a different prognosis, ranging from a KMT2A/AFDN (n = 11) to a 100% chance of survival for patients harboring the rare translocation KMT2A/SEPTIN9 (n = 3, follow up of 3.7 to 9.6 years). A positive correlation of KMT2A-r with KRAS mutations (p < 0.001) existed, albeit without any prognostic impact. In addition, FLT3-ITDs were detected less frequently in AML with KMT2A-r (p < 0.001). Furthermore, KMT2A-r were mutually exclusive, with mutations in NPM1 (p = 0.002), KIT (p = 0.036), WT1 (p < 0.001) and CEBPA (p = 0.006), and translocations NUP98/NSD1 (p = 0.009), RUNX1/RUNX1T1 (p = 0.003) and CBFB/MYH11 (p = 0.006). In the 346 patients tested for CSPG4 expression, a correlation between CSPG4 expression and KMT2A-r was confirmed. However, CSPG4 expression also occurred in patients without KMT2A-r and had no significant prognostic impact on EFS and OS.

Post-relapse therapy remains critical for survival in children with acute myeloid leukemia (AML). We evaluated survival, response and prognostic variables following relapse in independent cooperative group studies conducted by COG and the population-based AML-BFM study group. BFM included 197 patients who relapsed after closure of the last I-BFM relapse trial until 2017, while COG included 852 patients who relapsed on the last Phase 3 trials (AAML0531, AAML1031). Overall survival at 5 years (OS) was 42 ± 4% (BFM) and 35 ± 2% (COG). Initial high-risk features (BFM 32 ± 6%, COG 26 ± 4%) and short time to relapse (BFM 29 ± 4%, COG 25 ± 2%) predicted diminished survival. In the BFM dataset, there was no difference in OS for patients who had a complete remission with full hematopoietic recovery (CR) following post-relapse re-induction compared to those with partial neutrophil and platelet recovery (CRp and CRi) only (52 ± 7% vs. 63 ± 10%, p = 0.39). Among 90 patients alive at last follow-up, 87 had received a post-relapse hematopoietic stem cell transplant (HSCT). OS for patients with post-relapse HSCT was 54 ± 4%. In conclusion, initial high-risk features and early relapse remain prognostic. Response assessment with full hematopoietic recovery following initial relapse therapy does not predict survival. These data indicate the need for post-relapse risk stratification in future studies of relapse therapies.

Acute myeloid leukemia is a life-threatening malignant disorder arising in a complex and dysregulated microenvironment that, in part, promotes the leukemogenesis. Treatment of relapsed and refractory AML, despite the current overall success rates in management of pediatric AML, remains a challenge with limited options considering the heavy but unsuccessful pretreatments in these patients. For relapsed/refractory (R/R) patients, hematopoietic stem cell transplantation (HSCT) following ablative chemotherapy presents the only opportunity to cure AML. Even though in some cases immune-mediated graft-versus-leukemia (GvL) effect has been proven to efficiently eradicate leukemic blasts, the immune- and chemotherapy-related toxicities and adverse effects considerably restrict the feasibility and therapeutic power. Thus, immunotherapy presents a potent tool against acute leukemia but needs to be engineered to function more specifically and with decreased toxicity. To identify innovative immunotherapeutic approaches, sound knowledge concerning immune-evasive strategies of AML blasts and the clinical impact of an immune-privileged microenvironment is indispensable. Based on our knowledge to date, several promising immunotherapies are under clinical evaluation and further innovative approaches are on their way. In this review, we first focus on immunological dysregulations contributing to leukemogenesis and progression in AML. Second, we highlight the most promising therapeutic targets for redirecting the leukemic immunosuppressive microenvironment into a highly immunogenic environment again capable of anti-leukemic immune surveillance.

Successful management of relapse is critical to improve outcomes of children with acute myeloid leukemia (AML). We evaluated response, survival and prognostic factors after a second relapse of AML. Among 1222 pediatric patients of the population-based AML-Berlin–Frankfurt–Munster (BFM) study group (2004 until 2017), 73 patients met the quality parameters for inclusion in this study. Central review of source documentation warranted the accuracy of reported data. Treatment approaches included palliation in 17 patients (23%), intensive therapy with curative intent (n = 46, 63%) and other regimens (n = 10). Twenty-five patients (35%) received hematopoietic stem cell transplantation (HSCT), 21 of whom (88%) had a prior HSCT. Survival was poor, with a five-year probability of overall survival (pOS) of 15 ± 4% and 31 ± 9% following HSCT (n = 25). Early second relapse (within one year after first relapse) was associated with dismal outcome (pOS 2 ± 2%, n = 44 vs. 33 ± 9%, n = 29; p < 0.0001). A third complete remission (CR) is required for survival: 31% (n = 14) of patients with intensive treatment achieved a third CR with a pOS of 36 ± 13%, while 28 patients (62%) were non-responders (pOS 7 ± 5%). In conclusion, survival is poor but possible, particularly after a late second relapse and an intensive chemotherapy followed by HSCT. This analysis provides a baseline for future treatment planning.

BACKGROUND: Children with high risk acute myeloid leukemia (AML) still experience consistently high rates of relapse. Survival after first relapse increased from 21% between 1987 and 1997 up to 39% in recent studies. However, since 2009, there have been no publications on subsequent large pediatric AML relapse trials. As the indications for HSCT during first-line treatment have been extended since then, the current survival of these patients at relapse remains unclear. Herein, we report outcome results from the BFM and COG study group, which represents the largest available dataset analyzed for post-relapse survival. PATIENTS AND METHODS: Pediatric patients with first relapse of AML (no Down syndrome, secondary leukemia or FAB M3) have been analyzed from two large study groups with patients from the United States, Canada, Australia, New Zealand, Germany, Austria, Czech Republic and Switzerland. Out of 1222 patients in the BFM cohort (AML-BFM study 2004, registry 2012 and study 2012), 350 experienced at least one relapse and 197 of those had a first relapse after closure of the last I-BFM relapse trial (04/2009 through 2017). Within the Children's Oncology Group (COG) Phase 3 trials (AAML0531 and AAML1031, n=2119) 852 pediatric patients suffered a relapse. Five-year probability of overall survival (pOS) and event-free survival (pEFS) were calculated according to Kaplan-Meier. EFS was calculated for the BFM cohort as time from relapse to the next event (second relapse, death, failure to achieve a second remission or secondary malignancy) or until last follow-up, while OS reflects the time from relapse until death or last follow-up. The Cox proportional hazards model was used for multivariate analysis of outcomes. Living patients were censored at last follow-up with a median follow-up after relapse of 4·2 years (BFM) and 4·8 years (COG). Data have been frozen at 03/27/2020 (BFM) and 03/31/2020 (COG). RESULTS: In the 197 patients with relapse after closure of the last BFM relapse trial (04/2009 through 2017) the pOS at 5 years was 42±4% (BFM). The 5-year pOS in patients relapsing after COG trials 2006-2018 was 35±2% (n=852). Patients experiencing a relapse between 2014 to 2017 had a pOS of 49±6% (BFM, n=78) and 40±3% (COG, n=333). Risk classification at initial diagnosis and a short time from diagnosis to relapse predicted a diminished survival probability in both cohorts (see Table 1). However, the absence of full hematopoietic regeneration of the bone marrow after re-induction did not predict survival: Within the BFM dataset, a subgroup analysis in all patients receiving DNX-FLA (n=156) have been performed. Initial characteristics are comparable to the total cohort. Among these patients 147 were evaluable for response (7 excluded due to early death before evaluation, 2 for insufficient data). Eighty-nine (57%) achieved a CR (n=69) or CRp (n=20) and 52 (33%) no response. Overall survival was superior for patients with a CR/CRp (54±6% (CR/CRp) vs. 32±7% (No CR/CRp); p=0·0064), but long-term survival was still possible even with a poor re-induction response. Patients with a CRp had a comparable survival to those with a CR after a second re-induction (pOS 60±11% (CRp) vs. pOS 52±7% (CR); p=0·57). Patients with >5% leukemic blasts (n=32) had the lowest survival (pOS 27±9%). The 5-year pEFS for this cohort was 29±4% (pEFS 50±6% (CR) vs. pEFS 50±11% (CRp)). The analysis of post-relapse treatment showed that the vast majority of patients who survive had a HSCT following relapse. By landmark analysis, survival was significantly higher in patients with subsequent HSCT compared to that of non-transplanted patients (BFM: pOS 53±4%, n=154 vs. pOS 5±5%, n=21; p(Mantel-Byar)=0·0002). CONCLUSION: This is the largest report to date on post relapse survival in children with AML. Our analysis confirmed previously described risk factors for poor survival while also highlighting new findings contrary to established standards. Strikingly, the absence of full hematopoietic regeneration of the bone marrow after re-induction did not predict survival at first relapse, thereby questioning the current value of the established International Working Group Criteria published by Cheson et al for response-evaluation in pediatric AML. As the international pediatric AML community embarks on collaborative efforts to evaluate new therapies in children with relapsed AML, a comprehensive review of post relapse survival is critical. Disclosures: Bourquin: Servier: Other: Travel Support. Reinhardt:Novartis: Membership on an entity's Board of Directors or advisory committees; CLS Behring: Research Funding; bluebird bio: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Roche: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding.