Bortezomib is significantly beneficial for
de novo
pediatric AML patients with low phosphorylation of the NF‐κB subunit RelA
Abstract Acute myeloid leukemia (AML) accounting for approximately 17% of all childhood acute leukemias, arises either de novo or from a backround of myelodysplasia or previous chemotherapy. Cytogenetics is considered one of the most valuable prognostic determinants in AML while current risk–group classification in the limited cases of pediatric AML, is mainly based on cytogenetics and early treatment response. We reviewed the clinical and cytogenetic characteristics and the outcomes of 33 cases of childhood AML between 1997 and 2007 in order to investigate the incidence of the main FAB subtypes, the incidence of primary AML compared to secondary AML (s-AML) and the correlation between specific chromosome abnormalities and outcome in greek pediatric AML patients. Chromosome studies were performed on unstimulated bone marrow cells, derived from 33 pediatric AML patients, who were <18 years of age at the time of diagnosis. Eighteen patients were male and 15 were female. According to FAB classification one patient was classified as M0 (3%), 13 patients as M2 (39.4%), 4 as M3 (12.12%), 4 as M5 (12.12%), 2 as M6 (6.1%) and 4 as M7 (12.12%). No patient was classified as M4 while 5 patients with s-AML (15.15%) could not be classified. The median follow-up of all patients was 57.95 months (0.03–132.47). Overal survival and event free survival were 66,7% and 75,8% respectively. Eight patients with s-AML and 25 patients with primary AML were identified. The median age of patients with s-AML at diagnosis was 9.15 years while the median age of patients with primary AML was 7.2 years. Six out of 8 patients with s-AML died at a median follow up of 11.03 months. Nineteen out of 25 patients with primary AML are alive in complete remission (CR). Cytogenetic analysis was performed at diagnosis in 32 patients and results were obtained in 30 of them. The karyotype was abnormal in 21 out of 30 patients (70%). Normal karyotype was found in 9 patients, t(8;21)(q22;q22) in 5, t(15;17)(q22;q21) in 3, t(9;11)(p22;q23) in 3, −7/del(7q) in 5, del(9q) in 3, and complex karyotype in 4 patients. Three out of 4 patients with M3 are alive in CR with a median follow-up of 98.6 months while one with s-AML-M3 died 13 days post diagnosis. Three out of five patients with M2 and t(8;21), including 1 patient with s-AML, died at a median follow-up of 4.35 months. Three out of 5 patients with −7/del(7q) had s-AML and died in less than 4 years, while the two others are alive for more than 5 years, in CR. Although all patients with M7 had complex karyotypes, they are alive after a median follow-up of 96.73 months, 3 of them in CR and 1 in relapse. These results indicate that in greek patients, the main FAB subtypes show a distribution similar to that reported in the literature with the exception of M4 which is absent in our study but with a reported incidence of 20%. Pediatric patients with s-AML are older and their outcome is poor and is related to a higher probability of poor cytogenetic features compared to primary AML patients. Interestingly all patients with M7 had a good clinical course although they exhibited complex karyotypes.
Abstract Abstract 4257 Background Resistance to imatinib is one of the most important issues in treatment of CML. Proteasome inhibitor, bortezomib, is known to be effective in therapy of various neoplasms. Preclinical studies demonstrate the ability of bortezomib in chemosensitization and overcoming of chemotherapy resistance. Objective Analysis of ex vivo drug resistance to bortezomib and another 23 drugs including tyrosine kinase inhibitors (TKI) in CML, in comparison to acute adult and pediatric leukemia. Material and methods A total number of 241 patients entered the study, including: 106 Ph(-)ALL and 53 AML children (age 0.1-18, median 7 years) and 46 AML and 36 CML adults (age 18-69, median 41 years). All children were diagnosed as de novo leukemia, AML adults as de novo (n=20) or relapsed/refractory (n=26). Due to similar drug sensitivity, all adult AML patients were pooled into one group (Gil et al, Anticancer Res, 2007;27:4021). Among CML patients 19 had advanced disease; 16 were resistant to imatinib and 6 had ABL-kinase domain mutations (M244V, E255K, Y253H, M351T and 2 with F317L). Ex vivo drug resistance profile was studied by the MTT assay with the use of following drugs: prednisolone, vincristine, idarubicin, daunorubicin, doxorubicin, mitoxantrone, etoposide, L-asparaginase, melphalan, cytarabine, fludarabine, cladribine, thiotepa, treosulfan, 4-HOO-cyclophosphamide, thioguanine, bortezomib, topotecan, clofarabine and busulfan. CML patients were also tested for sensitivity to TKI: imatinib, dasatinib and nilotinib. Results CML cells were more resistant than AML blasts to following drugs: prednisolone (1.5-fold; p=0.037), vincristine (2.3-fold; p=0.004), doxorubicin (>6.9-fold; p<0.001), etoposide (7.4-fold; p<0.001), melphalan (5.9-fold; p=0.001), cytarabine (12.5-fold; p=0.005), fludarabine (2.6-fold; p=0.008), thiotepa (5.4-fold: p=0.001), 4-HOO-cyclophosphamide (2.3-fold; p=0.015), thioguanine (>4-fold; p<0.001), bortezomib (6.2-fold; p<0.001), topotecan (20-fold; p<0.001), and clofarabine (50-fold; p<0.001). No differences in sensitivity were found for idarubicin, daunorubicin, mitoxantrone, L-asparaginase, cladribine, and treosulfan, while CML cells were 2-fold more sensitive to busulfan (p=0.035). Adult and pediatric AML samples did not differ significantly in ex vivo drug resistance to all tested drugs. Pediatric AML samples were more resistant than pediatric ALL samples to most of tested drugs, however they had comparable sensitivity to cytarabine, thioguanine, bortezomib, and clofarabine. CML patients with mutation had higher ex vivo resistance to: vincristine (3.3-fold; p=0.044), idarubicin (7.9-fold; p=0.031), thiotepa (13.7-fold; p=0.044), and busulfan (21.6-fold; p=0.024). No significant differences were observed with respect to other drugs, including all 3 TKI's. CML patients resistant to imatinib had higher ex vivo resistance to: vincristine (2.5-fold; p=0.016), daunorubicin (3.1-fold; p=0.011), etoposide (2.2-fold; p=0.031), and busulfan (4.5-fold; p=0.032). No significant differences were observed in respect to other drugs, including all 3 TKI's. No significant differences were observed between CML patients with non-advanced and advanced disease to all tested drugs, including TKI's. Conclusions CML cells are ex vivo more resistant to most drugs than acute leukemia blasts. Bortezomib alone has no ex vivo activity in CML patients. No differences between CML subgroups in sensitivity to 3 various TKI was detected. These findings require further investigations. Acknowledgments This study was supported by grants: EC 2008/2009 ZPORR SPS.IV-3040-UE/217/2009; EFS 9/9/POKL/4.4.1/2008; UMK 09/2009 and MNiSW N407 078 32/2964. Disclosures: No relevant conflicts of interest to declare.
Abstract Abstract 4899 [Background] The WHO classification has been widely accepted among physicians who are engaged in treating pediatric AML patients. In 2008, the revised WHO classification has expanded the two categories in AML; AML with recurrent genetic abnormalities and AML with myelodysplasia-related changes. The epidemiology and prognostic significance of these refined categories remains to be explored in children. [Methods] JPLSG AML-05 is a nationwide clinical trial for children with de novo AML, excluding acute promyelocytic leukemia and myeloid leukemia with Down syndrome, which was conducted between November 2006 and December 2010 in Japan. A central review of diagnosis based on the WHO classification was prospectively performed on each case soon after morphological, cytogenetical and immunological data were submitted to data center. Regarding the cases with discrepant results among these parameters, further diagnostic tests including FISH and chimera gene analyses were underwent to confirm the diagnoses. [Results] Four hundred and eighty four patients were enrolled in the study. Thirty patients did not meet the criteria of AML. We could not collected suitable data for diagnosis in 6 patients. Regarding the rest 448 patients, diagnoses based on the WHO classification 2001 and 2008 were determined. According to the 2001 version, 227 (50.6%) had AML with recurrent genetic abnormalities:124 (27.7%) of AML with t(8;21)(q22;q22);(AML1/ETO ), 32 (7.1%) of AML with inv(16)(p13q22); (CBFβ/MYH11), 38 (8.5%) of AML with t(9;11)(p22;q23), and 33 (7.4%) of AML with the other11q23 (MLL) abnormalities, 36 (8.0%) had AML with multilineage dysplasia, and 185 (41.3%) had AML, not otherwise categorized. According to 2008 version, 235 (52.5%) had AML with recurrent genetic abnormalities: 124 (27.7%) of t(8;21)(q22;q22);(AML1/ETO ), 32 (7.1%) of AML with inv(16)(p13q22); (CBFβ/MYH11), 38 (8.5%) of AML with t(9;11)(p22;q23), 33 (7.4%) of AML with the other11q23 (MLL) abnormalities,4 of AML with t(6;9)(p23;q34);DEK-NUP214,2 of AML with inv(3)(q21q26.2) or t(3;3)(q21;q26.2);RPN1-EVI13, and 2 of AML with t(1;22)(p13;q13);RBM15-MKL, 88 (19.6.7%) had AML with myelodysplasia-related changes (29 from morphological features of myelodysplasia and 59 from myelodysplasia-related cytogenetic abnormalities), 119 (26.6%) had AML, not otherwise categorized and 7(1.6%) had mixed phenotype acute leukemia (6 of T/myeloid and 1 of B/myeloid). [Discussion] Our comprehensive approach for diagnosis was a useful modality for precise diagnosis of uncertain cases, which might have been assigned to the category of AML, with not otherwise categorized, previously. As a result, the present study shows an increased prevalence of AML with recurrent genetic abnormalities or AML with myeloid dysplasia-related changes among pediatric patients with previously untreated AML. Analysis of the AML-05 trial will elucidate the prognostic impact of these categories. Disclosures: No relevant conflicts of interest to declare.
Abstract Abstract 4283 Background The role of Gemtuzumab ozogamicin (GO) for acute myeloid leukemia (AML) remains controversial. GO was removed from the U.S. market in 2010 due to concerns of increased induction mortality in adults. Other studies have shown a survival benefit without increased treatment related mortality. Moreover, no data are available on the resources required to deliver GO based chemotherapy. Since pediatric data are limited, we evaluated in-hospital mortality and resource utilization in pediatric AML patients treated with GO and standard chemotherapy. Methods We used the Pediatric Information Health System (PHIS) to establish a cohort of children < 19 years old treated for de novo AML with GO and standard cytarabine, daunorubicin, and etoposide (ADE) induction. Cohort assembly was validated by local chart review and used ICD-9 diagnosis codes and manual review of chemotherapy. Case fatality was determined after induction (defined from the start of therapy to the initiation course 3), at 6 months and at 12 months. Resource utilization was determined for each patient based on daily billing data. Each resource variable was dichotomized (exposure or no exposure) for each inpatient day and then summarized during each study period to determine resource utilization days per 1,000 hospital days. Results In total, 253 children who had billing data for GO during the first course of ADE induction were identified. Median age was 9.6 years; a slight male predominance was observed (54%) and most patients were white (69%). In-hospital case-fatality rates were 2.4% during induction, 6.7% at 6 months, and 13.0% at 12 months from start of therapy. PHIS billing data demonstrated that patients received opioids almost on one in four hospital days, that during induction period 12% of patients received vasopressors on at least two consecutive days, and 12% needed assisted ventilation. Mean inpatient stay and resource utilization rates are presented in Table 1. Discussion In-hospital mortality rates at the three time points were low and concordant with published data on pediatric AML trials using an ADE induction (Gibson, BJH 2011) and ADE Induction + GO (Cooper, Cancer 2012) and lower than trials using intensively timed DCTER regimens (Woods, Blood 2001; Lange, Blood 2008). Resource utilization data demonstrated an extensive use of resources needed to manage infections (blood cultures, imaging, antimicrobials). While infections are the leading cause of non-relapse morbidity and mortality in pediatric AML, such extensive use of resources has not been previously quantified. In addition, PHIS billing data describe toxicities such as pain (opioid use), hypotension (vasopressor support), and respiratory failure (assisted ventilation) at rates higher than those previously reported in clinical trials. In conclusion, the in-hospital mortality of children treated with GO at PHIS centers appears comparable to previously published studies of ADE and ADE + GO. The resource utilization data provide a more comprehensive description of resources needed to treat pediatric AML than previously reported. In addition, the resource utilization data suggest that toxicities reported on clinical trials may underestimate the resources needed to administer AML induction therapy safely. Disclosures: No relevant conflicts of interest to declare.
Abstract The Casitas B-Lineage Lymphoma (CBL) gene encodes for an E3 ubiquitin ligase that targets activated receptor tyrosine kinases for degradation. Mutations of the CBL gene have been described in juvenile myelomonocytic leukemia (JMML) but less is known about mutations and variants of CBL in de novo AML. We previously reported that somatic mutations of CBL are rare in pediatric AML. In this report we present a comprehensive evaluation of genomic and transcript variants of CBL including novel deletion events as well as transcript variants which, in combination with somatic mutations, account for over 6% of pediatric AML with extreme association with inv(16) and favorable outcome. Initial assessment of CBL transcript in a cohort of 100 patients identified previously reported deletion of exon 8 (CBL ΔE8, N=2) associated with CBL splice mutations as well as a novel whole exon 8 and 9 deletion variant (CBL ΔE8+9, N=3) without identifiable underlying somatic alterations. Long distance PCR, as well as custom Nanostring CNV array evaluation revealed a genomic deletion underlying this transcript variant. Subsequent whole genome sequencing as part of COG/NCI TARGET AML initiative, identified discrete genomic deletions of 1998, 3588 and 6189 bp across exon 8 and 9, leading to the generation of this novel variant. We evaluated the functional consequence of the novel CBL ΔE8+9 deletion variant by expressing it in IL3-dependent Ba/F3 cell line. Compared to control cells, Ba/F3 cells expressing CBL ΔE8+9 demonstrated cytokine independent growth. A comprehensive profiling of CBL variants was conducted in 796 pediatric de novo AML patients by transcript profiling (transcript variants) or by exome capture sequencing (somatic mutations including point mutations and smaller indels). All patients were treated on Children's Oncology Group studies AAML03P1 (N=167) and AAML0531 (N=629) and presence of CBL variants was correlated with disease characteristics and clinical outcome. Of the 796 patient specimens tested, 50 patients (6.3%) had one of 3 distinct CBL variants; transcript variant (N=28), somatic mutation (N=14), or dual transcript variant and somatic mutation (N=8). All cases of CBL ΔE8+9 were associated with a corresponding genomic deletion. Out of 14 cases of CBL ΔE8 and 1 case of CBL ΔE9, only 4 cases (27%) had a splice site mutation identified as the underlying mechanism of splice variant. Presence of CBL variants was correlated with clinical characteristics and outcome. Those with CBL variants had a significantly higher prevalence of inv(16) compared with CBL wild type (WT) (37% vs. 13%, p<0.001). This association differed by CBL variant type; 44% transcript variants and 50% dual variants had inv(16) compared to 14% somatic mutations and 13% CBL WT (p<0.001). NPMc+ was more prevalent in those with CBL somatic mutations (29%) than transcript variant (4%), dual variant (0%) or CBL WT (8%) (p=0.035). Similarly, genetic risk groups differed between CBL variants vs. WT (Low risk 70% vs 39%, p=<0.001; Standard risk 22% vs. 46%, p=0.001; High risk 8% vs. 15%, p=0.196). Clinical characteristics including gender, age, race and ethnicity were not significantly different. FAB morphologic assessment revealed an enrichment for the M4 subtype in CBL variant vs. WT (53% vs. 23%, P<.001) which is likely accounted for by the association of inv(16) with this morphologic group. Patients with CBL variants had a 100% clinical remission rate by end of induction II compared to 89% for CBL WT patients (p=0.014). Survival from study entry was similar between CBL mutant vs. WT patients (5 year OS 72% vs. 66%, p=0.24; 5 year EFS 61% vs. 50%, p=0.11). Due to the strong association of CBL mutation with core binding factor leukemia, we assessed whether CBL variant was prognostic of outcome within this favorable risk group, but there was no significant difference in outcomes. Variants of the CBL gene in pediatric AML include genetic mutations with and without whole exon deletions. These CBL variants are highly associated with low risk AML but do not provide independent risk prognosis. The cooperating events of CBL variants in core binding factor leukemia deserve greater study. Our initial analysis of the transcript variants in a cell line model suggest that these large exon 8+9 deletions represent important oncogenic events. The authors would like to gratefully acknowledge the important contributions of the late Dr. Robert Arceci to the AML TARGET initiative. Disclosures No relevant conflicts of interest to declare.
Genomic Landscape and Prognosis in Pediatric Acute Myeloid Leukemia: A Study on the French ELAM02 Trial
Abstract Background. Acute Myeloid Leukemia (AML) is a rare and genetically heterogeneous disease that constitutes 15 to 20% of childhood leukemia. Despite major treatment improvement over the past decades pediatric AML remains a challenging disease with poor outcome compared to acute lymphoid leukemia (ALL). About 50% of these patients relapse after standard intensive chemotherapy. Molecular analysis pointed out the prognostic impact of gene mutation such as FLT3-ITD, NPM1 or CEBPA; and new categories of regulators like epigenetic modifiers. More recently mutational profiling studies revealed distinct molecular subgroups with prognostic significant and stratification in adult AML. Nevertheless cytogenetic and mutational profiles are quite different between adult and pediatric AML. Extensive genomic studies have not been reported to date in pediatric AML. In this context it is of importance to identify additional genetic or molecular abnormalities to better understand leukemogenesis and also to predict outcome and serve as novel therapeutic targets. Methods. We performed a mutational analysis on diagnostic samples from patients enrolled in the French National Multicenter ELAM02 trial. 438 patients with de novo AML (except AML3) were enrolled between march 2005 and December 2011 (median age: 8,22yrs [0-18.61]; median WBC: 15.4G/l [0.4-575]; cytogenetic subgroups: CBF-AML[n=97], NK-AML [n=109], MLL-AML[n=95], MRC2 other[n=77], MRC3 [n=55], failure [n=5]). Diagnostic samples were prospectively collected and 386 of the 438 patients (88%) were studied by next-generation sequencing (Miseq, Illumina with haloplex librairy and ion Proton, thermofischer with ampliseq librairy) including 36 genes frequently reported in myeloid malignancy. Two different technologies of next generation sequencing (NGS) were used, allowing direct validation. FLT3-ITD was detected and quantified by Genescan analysis. Results. We identified 579 driver mutations involving 36 genes or regions in 386 patients (mean 1.5 per case), with at least 1 driver mutation in 291 patients (75%) and 2 or more driver mutations in 44% of samples. The number of mutation identified at diagnosis in cytogenetic subgroup is significantly lower in MLL-AML (0.44 mutation/patient; p<10-4). Mutations involving genes from the tyrosine kinase pathways (i.e RAS, FLT3, KIT, PTPN11, JAK2, MPL, CBL) were the most frequent and represent 56.3% of all aberrations. Among them N-RAS was detected in 26.4% of all cases, followed by FLT3-ITD, KIT and K-RAS in 14.8%, 12.4% and 12.2% respectively. We identified 64 driver mutations in the group of transcription factors (CEBPA, RUNX1, GATA, ETV6), 60 in the combined group of chromatin modifier (ASXL1, EZH2, BCOR) and DNA methylation (DNMT3A, IDH, TET2), 59 in the group of tumor suppressor genes (WT1, PHF6, TP53) 36 mutations in NPM1 gene, and few mutations in cohesion and spliceosome sub-groups. Identified mutations are indicated in the figure according cytogenetic subgroups. Among the 438 patients, 398 (91%) were in complete remission (CR) after two courses (induction and first consolidation), the 5-year overall survival (OS) is 71.5% [65-78] and the 5-year leukemia free survival (LFS) is 56.6% [49.7-63.5]. In univariate analysis, we found that FLT3-ITD, mutations in RUNX1, WT1 and PHF6 were associated with reduced LFS (p=0.0003 for FLT3-ITD, p=0.01 for RUNX1, p=0.02 for WT1 and p=0.025 for PHF6) and reduced OS (p=0.0003 for FLT3-ITD, p=0.0003 for RUNX1, p=0.015 for WT1 and p=0.04 for PHF6). Mutations in NPM1 is associated with an improved 5-yr LFS (p=0.014) and 5-yr OS (p=0.005). Multivariate analysis revealed that FLT3-ITD, RUNX1 and PHF6 were independently associated with an adverse outcome and NPM1 with an improved outcome. Conclusions. We performed an extensive mutational study in de novo pediatric AML enrolled in the ELAM02 trial. We described the genomic landscape of 386 patients and showed the frequency of different mutations according cytogenetics. Interestingly we found mutations in genes involved in constitutional or pre-leukemic disease such as PTPN11, RUNX1, MPL or ETV6. We found that FLT3-ITD, RUNX1 and PHF6 mutations predict poor outcome although NPM1 mutations predict a better outcome. Mutational profiling reveals useful information for risk stratification and therapeutic decisions. Figure Figure. Disclosures Baruchel: Amgen: Consultancy.
Bortezomib (BTZ) was recently evaluated in a randomized Phase 3 clinical trial which compared standard chemotherapy (cytarabine, daunorubicin, etoposide; ADE) to standard therapy with BTZ (ADEB) for de novo pediatric acute myeloid leukemia. While the study concluded that BTZ did not improve outcome overall, we examined patient subgroups benefitting from BTZ-containing chemotherapy using proteomic analyses. The proteasome inhibitor BTZ disrupts protein homeostasis and activates cytoprotective heat shock responses. We measured total heat shock factor 1 (HSF1) and phosphorylated HSF1 (HSF1-pSer326) in leukemic cells from 483 pediatric patients using Reverse Phase Protein Arrays. HSF1-pSer326 phosphorylation was significantly lower in pediatric AML compared to CD34+ non-malignant cells. We identified a strong correlation between HSF1-pSer326 expression and BTZ sensitivity. BTZ significantly improved outcome of patients with low-HSF1-pSer326 with a 5-year event-free survival of 44% (ADE) vs. 67% for low-HSF1-pSer326 treated with ADEB (P=0.019). To determine the effect of HSF1 expression on BTZ potency in vitro, cell viability with HSF1 gene variants that mimicked phosphorylated (S326A) and non-phosphorylated (S326E) HSF1-pSer326 were examined. Those with increased HSF1 phosphorylation showed clear resistance to BTZ vs. those with wild type or reduced HSF1-phosphorylation. We hypothesize that HSF1-pSer326 expression could identify patients that benefit from BTZ-containing chemotherapy.
Abstract Background Pediatric acute myeloid leukemia (AML) is a rare disease with roughly 600 cases diagnosed in the United States each year with minimal improvement in clinical outcomes over the last few decades. We previously demonstrated that an ex vivo drug sensitivity assay (DSA) can predict clinical response in myelodysplastic syndrome (Spinner et al. Blood Adv 2020). Here we investigated whether the DSA performed on pre-induction pediatric AML samples correlates with clinical response and can identify potent novel drug combinations. Methods Pre-induction blood or bone marrow samples were assayed from 20 de novo pediatric AML patients diagnosed at Texas Children's between 5/2015 and 10/2020. All patients consented to research (82% enrolled in clinical trial identifier NCT03568994) and received ADE (Cytarabine, Daunorubicin, and Etoposide), and next-generation sequencing was done as part of clinical care. Risk stratification was per AAML1831 guidelines. Drug sensitivity data was analyzed from 13/20 samples that passed quality control with matched treatment conditions: 9/13 (69%) patients had M1/M2 histology, 3/13 (23%) were M4/M5 and 1/13 (8%) was M7 with a median age of 12.3 years. For the ex vivo DSA, samples were incubated in conditioned media and treated with a single dose of up to 25 unique compounds and up to 149 drug combinations. After 72 hours, changes in tumor blast populations were assessed by flow cytometry using an 11-marker panel to identify blasts. For each treatment condition, drug sensitivity was calculated based on the number of blasts remaining after treatment compared to DMSO control. Clinical response data, including minimal residual disease (MRD) percentage by flow cytometry, and 1-year relapse-free survival (RFS), were correlated with drug sensitivity results. Log odds ratios (OR) were calculated with the Haldane-Anscombe correction. ORs were used to quantitatively measure the association between clinical attributes and the DSA to the clinical response data. For evaluation of ORs, a normalized blast score of 70% viability was used to maximize the separation between high and low drug sensitivity. Results Ex vivo drug sensitivity correlated with both MRD (r=0.63) and 1-year RFS (r=0.59) in the de novo patient subset (Fig A). Three patients with an MRD >1% exhibited low ex vivo sensitivity to ADE, and among these 3 patients, 2 did not achieve 1-year RFS. Results from the DSA predicted increased odds of having an MRD >1% compared to demographic and mutational clinical attributes that showed weaker associations with MRD (Fig B). Of the 77 treatment conditions that were tested in 13 patient samples, Bortezomib in combination with Panobinostat (B/P) was the most efficacious treatment in the DSA, where drug sensitivity ranged from low (>100% blast viability) to high (0% blast viability). Separation of patient samples into two distinct low and high DSA response groups was observed with B/P, whereas ADE and single agents showed a graded distribution (Fig C). Within these response groups, pAML3 showed low sensitivity to ADE in the ex vivo DSA and the patient did not respond to ADE. In contrast, pAML8 showed high sensitivity to ADE ex vivo and the patient responded to ADE treatment. While pAML3 and pAML8 showed similar ex vivo sensitivity to B/P as for ADE (Fig D), pAML4 showed preferential sensitivity to ADE and not B/P, and conversely pAML6 showed sensitivity to B/P and not ADE. Conclusion Ex vivo drug sensitivity to ADE correlates with both MRD and 1-year RFS in a cohort of 13 de novo pediatric AML patients. These results suggest that clinical response in pediatric AML may be assessed prior to treatment using an ex vivo drug sensitivity assay. Compared to demographic and mutational clinical characteristics queried, ex vivo drug sensitivity to ADE has the potential to be a more predictive measure compared to clinical attributes alone. Combining genomics with functional ex vivo drug sensitivity data could further enhance precision medicine and biomarker discovery in pediatric AML. The DSA also highlights Bortezomib/Panobinostat as a potential novel drug combination for pediatric AML, and the ability to identify a patient sample that is insensitive to ADE and sensitive to Bortezomib/Panobinostat ex vivo supports the use of the DSA to not only predict clinical response but also to possibly inform treatment decisions for pediatric AML patients. Figure 1 Figure 1. Disclosures Strachan: Notable Labs: Current Employment, Current holder of stock options in a privately-held company. Gu: Notable Labs: Current Employment, Current holder of stock options in a privately-held company. Kita: Notable Labs: Current Employment, Current holder of stock options in a privately-held company. Richardson: Notable Labs: Current holder of stock options in a privately-held company, Ended employment in the past 24 months. Anderson: Notable Labs: Current holder of individual stocks in a privately-held company, Ended employment in the past 24 months. Santaguida: Notable Labs: Consultancy, Current holder of individual stocks in a privately-held company, Ended employment in the past 24 months, Patents & Royalties.
Abstract The t(6;9)(p23;q34) translocation, which results in the formation of a chimeric fusion gene DEK/CAN on the der(6) chromosome, is a rare recurring cytogenetic aberration reported in patients (pts) with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Because the abnormality is an infrequent finding in AML with most reports describing 2 to 8 cases, the US Intergroup Cytogenetics Consortium investigated the frequency and clinical, pathologic and cytogenetic characteristics of t(6;9) leukemia among pts registered to 19 different treatment protocols. Among 6567 pts with evaluable karyotypes, 62 (0.9%) had t(6;9): 30 on pediatric trials (mean 12 yrs; 15/15 male/female) and 32 on adult trials (mean 38 yrs; 21/11 male/female), compared to the mean age of 8 yrs for pts on pediatric AML/MDS trials and 54 yrs for pts on adult AML/MDS trials. Three cases (5%) showed a complex (3- or 4-way) variant translocation and only 7 (11%) of the 62 pts showed secondary aberrations: 3 (10%) of 30 pediatric cases and 4 (13%) of 32 of the adult cases. The majority of t(6;9) cases were classified as FAB-M2 (34%), M4 (31%) or M1 (19%). Although the immunophenotyping (N=7) and morphology data (N=17) were limited, increased basophilia and Auer rods were observed and the blasts showed CD13, CD15, and CD33 expression, in agreement with a previously reported preliminary study (Am J Clin Pathol107:430–437,1997). Four pts (1 pediatric and 3 adults) had MDS. Among the remaining 58 pts, 25 (78%) adults had previously untreated AML (16 de novo, 2 secondary, and 7 unknown secondary/de novo status) while all 29 pediatric AML patients had de novo AML. For the 54 patients with previously untreated AML, complete remission rates were slightly higher, but not statistically significantly (p=.20) in children (69%), when compared to adults (52%). Disease-free survival (DFS) (combined median 8.8 mo, 95% CI, 5.1–13.7) and overall survival (OS) (combined median 11.9 mo, 95% CI, 10.0–14.3) were poor regardless of age, a finding in distinct contrast to the t(8:21) favorable risk group also commonly observed in M2/M4 AML. Kaplan-Meier estimates of 3-yr survival were 25% for pediatric cases and 9% for adults. Analysis of stem cell transplantation (SCT) was inconclusive due to the small number of transplanted patients (N=15), but suggested that allogeneic SCT might be associated with better OS than no SCT (hazard ratio [HR] 0.39 after SCT, 95% CI 0.14 – 1.11), while autologous SCT might not (HR 1.49, 95% CI 0.57–3.85). Based on this study of t(6;9), largest to date and previously published data, AML with t(6;9) leukemia is a distinct AML subgroup with distinguishing clinicopathological features including poor outcome in relatively young patients, not explained by other known poor prognostic factors that warrants novel therapeutic strategies. Similar to other recurring cytogenetic abnormality subtypes of de novo acute myeloid leukemia of the WHO classification, t(6;9) may warrant a specific leukemia disease subtype.
Abstract Despite improvements in the treatment of children with de novo acute myeloid leukemia (AML), a substantial fraction of patients experience relapse. The Children’s Oncology Group Phase I trial, AAML00P2, sought to test the safety and feasibility of combining Gemtuzumab (GMTZ) with a standard AML reinduction regimen of mitoxantrone and cytarabine in a dose de-escalation design. Patients received cytarabine 1000 mg/m2/dose every 12 hours on days 1–4 with mitoxantrone 12 mg/m2/dose daily on days 3–6. The starting dose of GMTZ for dose finding was 3 mg/m2 once on day 7. Doses for patients under 3 years of age were as follows: cytarabine 33 mg/kg/dose, mitoxantrone 0.4 mg/kg/dose, and GMTZ 0.1 mg/kg/dose. Three patients were enrolled in the dose finding strata and an additional 18 patients were subsequently enrolled to acquire further toxicity data. Of these, 15 were male and 6 female. The median patient age was 11.3 years, range 1.2 to 19.2 years. No patients in the initial dose finding cohort experienced a dose limiting toxicity. Toxicities observed in the entire cohort of 21 patients included hematologic and infectious complications typical of AML therapy. One patient had grade III bilirubin elevation. No patients had grade III or IV hepatic toxicity or grade III or IV veno-occlusive disease (VOD). Data on toxicity in stem cell transplant post GMTZ exposure is limited. However, no episodes of VOD have been reported. In summary, GMTZ combined with cytarabine and mitoxantrone is reasonably well tolerated in pediatric AML patients.
