Response In Acute Myeloid Leukemia Research Articles

Characterization of m6A regulator-mediated methylation modification patterns and tumor microenvironment infiltration in acute myeloid leukemia.

BackgroundPrevious studies have confirmed the existence of epigenetic regulation of immune responses in acute myeloid leukemia. However, the potential role of RNA N6‐methyladenosine (m6A) remodeling in tumor microenvironment (TME) infiltration remains unclear.Methods and Materialsm6A patterns of 469 AML patients (420 of which provided survival data) based on 18 m6A regulators were systematically evaluated. Based on the expression of 18 m6A regulators, unsupervised agglomerative cluster analysis was applied to recognize the various m6A modification types and to classify patients. We linked these patterns to TME infiltration characteristics and identified three distinct populations of m6A modifications.ResultsThese three TME cell infiltration patterns are characterized by a high degree of concordance with the three tumor immunophenotypes, which include immunoinflammatory, immunorejection, and immune inert patterns. We showed that assessment of m6A modification patterns within individually neoplasms can forecast the stage of neoplasmic inflammation, TME basal activity, subtype, hereditary mutation, and clinical patient prognosis. Limited low m6Ascore, featuring increased mutational load and immune activation, indicates an inflammatory phenotype of TME with a 5‐year survival rate at 14.4% compared to the high‐m6Ascore group (40.9%).ConclusionsData from two different cohorts demonstrated that a higher m6Ascore showed a marked therapeutic superiority as well as clinical advantage. Assessing m6A modification patterns in AML patients could improve our knowledge of the TME infiltrative profile as well as directing effective immunotherapeutic approaches.

Isocitrate dehydrogenase mutations are associated with altered IL-1β responses in acute myeloid leukemia.

Mutations in isocitrate dehydrogenase 2 (IDH2) have been noted to impact cellular differentiation in addition to DNA and histone methylation. However, little is known about the impact of IDH2 mutations on intracellular signaling. Using an isogenic cell line model, we investigated both differentiation and signaling responses in IDH2 mutant cells and show augmented responses to inflammatory immune ligands. Using phospho-specific flow and mass cytometry, we demonstrate IDH2mutant cells were significantly more sensitive to IL-1β at multiple downstream readouts. Further, bulk RNA sequencing confirmed increases in cytokine-related signaling pathways and NF-κB target genes. Single-cell RNA sequencing of unstimulated and stimulated cells confirmed altered IL-1β transcriptional responses in the IDH2 mutant cells. Targeted inhibition of the IKK complex reduced IL-1β responses and induced cell death in primary IDH-mutated leukemia samples. Together, these results confirm altered IL-1β signaling in IDH2 mutant cells and identify this pathway as a potential therapeutic target.

Clonal architecture predicts clinical outcomes and drug sensitivity in acute myeloid leukemia

The impact of clonal heterogeneity on disease behavior or drug response in acute myeloid leukemia remains poorly understood. Using a cohort of 2,829 patients, we identify features of clonality associated with clinical features and drug sensitivities. High variant allele frequency for 7 mutations (including NRAS and TET2) associate with dismal prognosis; elevated GATA2 variant allele frequency correlates with better outcomes. Clinical features such as white blood cell count and blast percentage correlate with the subclonal abundance of mutations such as TP53 and IDH1. Furthermore, patients with cohesin mutations occurring before NPM1, or transcription factor mutations occurring before splicing factor mutations, show shorter survival. Surprisingly, a branched pattern of clonal evolution is associated with superior clinical outcomes. Finally, several mutations (including NRAS and IDH1) predict drug sensitivity based on their subclonal abundance. Together, these results demonstrate the importance of assessing clonal heterogeneity with implications for prognosis and actionable biomarkers for therapy.

M6A Regulator-Mediated Methylation Modification Patterns and Tumor Microenvironment Infiltration Characterization in Acute Myeloid Leukemia.

Recent studies have demonstrated epigenetic regulation of immune responses. Nevertheless, the underlying effect of RNA N6-methyladenosine (m6A) modifications on tumor microenvironment cell infiltration remains elusive. In this study, we thoroughly assessed m6A modification patterns of 255 myeloid leukemia specimens based on 23 m6A regulators. Consensus clustering of the 23 m6A regulators was performed to determine three distinct m6A modification patterns that were remarkably consistent with three immunophenotypes of tumors: immunorejection, immune activation, and immune inertness. Further evaluation and prognostic analysis of the m6A modification patterns of individual tumors revealed that low m6A score was characterized by increased mutational burden, immune activation, and survival rates, whereas high m6A score was characterized by poorer survival rates and the absence of effective immune infiltration. In addition, this study investigated the association between m6A regulators and antitumor immune responses and discovered higher expression of the immune regulators PD-L1, PD-L2, MRP1, and MRP2 in low m6A scores. Generally, the expression pattern of m6A regulators was remarkably associated with prognostic results and antitumor immune responses in acute myeloid leukemia and may be an underlying target and biological marker for immune therapies.

Identification of m6A-Related lncRNAs Associated With Prognoses and Immune Responses in Acute Myeloid Leukemia.

Background: Acute myeloid leukemia (AML) remains the most common type of hematopoietic malignancy in adults and has an unfavorable outcome. Herein, we aimed to construct an N6-methylandenosine (m6A)-related long noncoding RNAs (lncRNAs) signature to accurately predict the prognosis of patients with AML using the data downloaded from The Cancer Genome Atlas (TCGA) database. Methods: The RNA-seq and clinical data were obtained from the TCGA AML cohort. First, Pearson correlation analysis was performed to identify the m6A-related lncRNAs. Next, univariate Cox regression analysis was used to determine the candidate lncRNAs with prognostic value. Then, feature selection was carried out by Least absolute shrinkage and selection operator (LASSO) analysis, and seven eligible m6A-related lncRNAs were included to construct the prognostic risk signature. Kaplan–Meier and receiver operating characteristic (ROC) curve analyses were performed to evaluate the predictive capacity of the risk signature both in the training and testing datasets. A nomogram was used to predict 1-year, 2-year, and 3-year overall survival (OS) of AML patients. Next, the expression levels of lncRNAs in the signature were validated in AML samples by qRT-PCR. Functional enrichment analyses were carried out to identify probable biological processes and cellular pathways. The ceRNA network was developed to explore the downstream targets and mechanisms of m6A-related lncRNAs in AML. Results: Seven m6A-related lncRNAs were identified as a prognostic signature. The low-risk group hold significantly prolonged OS. The nomogram showed excellent accuracy of the signature for predicting 1-year, 2-year and 3-year OS (AUC = 0.769, 0.820, and 0.800, respectively). Moreover, the risk scores were significantly correlated with enrichment in cancer hallmark- and malignancy-related pathways and immunotherapy response in AML patients. Conclusion: We developed and validated a novel risk signature with m6A-related lncRNAs which could predict prognosis accurately and reflect the immunotherapy response in AML patients.

Vesicular trafficking is a key determinant of the statin response in acute myeloid leukemia

AbstractCholesterol homeostasis has been proposed as one mechanism contributing to chemoresistance in AML and hence, inclusion of statins in therapeutic regimens as part of clinical trials in AML has shown encouraging results. Chemical screening of primary human AML specimens by our group led to the identification of lipophilic statins as potent inhibitors of AMLs from a wide range of cytogenetic groups. Genetic screening to identify modulators of the statin response uncovered the role of protein geranylgeranylation and of RAB proteins, coordinating various aspect of vesicular trafficking, in mediating the effects of statins on AML cell viability. We further show that statins can inhibit vesicle-mediated transport in primary human specimens, and that statins sensitive samples show expression signatures reminiscent of enhanced vesicular trafficking. Overall, this study sheds light into the mechanism of action of statins in AML and identifies a novel vulnerability for cytogenetically diverse AML.

Feasibility of Capturing AML Morphologic Response Assessments Using Real-World Data

Background: Response in acute myeloid leukemia (AML) is based on morphologic evaluation of bone marrow (BM) and peripheral blood lab-based assessments. Electronic health records (EHRs) hold structured information on peripheral blood assessments, but it may be incomplete; unstructured documents containing BM morphologic evaluations can be abstracted to derive data on morphologic leukemia-free state (MLFS). The objective of this analysis was to assess the feasibility of capturing MLFS using EHR with enough completeness for analytic use. The association of MLFS status with real-world time to next treatment (rwTTNT) and real-world overall survival (rwOS) was evaluated.Methods: This analysis utilized data from the nationwide Flatiron Health EHR-derived de-identified database and included 2,560 patients diagnosed with AML who initiated first line therapy(1L) with either 7+3 regimen or a hypomethylating agent (HMA) + venetoclax between January 1, 2014 and February 28, 2021; with follow up through May 31, 2021. Evidence of MLFS using abstracted data from BM biopsies was defined as ≤ 5% blasts in the BM, no Auer rods, and no extramedullary disease. Patients' first BM biopsy in the EHR that occurred between 14 to 60 days after 1L initiation were used to assess MLFS in investigations of rwTTNT and rwOS, regardless of MLFS completeness. The Kaplan-Meier method was used to evaluate the association of MLFS with rwTTNT and rwOS landmarked at 60 days after 1L initiation to account for differences in time between 1L initiation and MLFS assessment.Results: Among the full cohort, 2,142 (84%) patients had a BM biopsy at any point during 1L. The median and mean number of biopsies in the EHR per patient that occurred during 1L were 2 and 2.5 (SD: 1.6), respectively, with a range of 1 to 13 biopsies per patient. There were 5,328 BM biopsies across all patients during 1L, and complete information was available to derive MLFS status for 4,584 (86%) biopsies. Blast percentage was the most frequently missing component. There were 1,811 (70%) patients who had a BM biopsy between 14 and 60 days after 1L initiation. There were 2,589 BM biopsies across all patients between 14 and 60 days after 1L initiation, and complete information was available to derive MLFS status for 2,259 (87%) of biopsies. All 1,811 patients with a BM biopsy between 14 and 60 days after 1L initiation had complete information to ascertain MLFS status on at least one biopsy. The median time between 1L initiation and the first BM biopsy that occurred at least 14 days after 1L initiation was 44 days.There were 1,573 patients (with BM biopsy in 14-60 days post 1L) included in analyses of rwTTNT and rwOS (238 patients were excluded due to incomplete information on MLFS components on their first BM biopsy). Patients without complete information to derive MLFS status were less likely to be an advanced age at diagnosis (75+), more likely to be seen at an academic practice, and had longer average follow-up (Table 1). Among patients with complete information to derive MLFS status, 1,123 patients had evidence of MLFS and 450 patients had no evidence of achieving MLFS. When landmarked at 60 days after 1L initiation, median rwTTNT was 5.8 months (95% CI: 4.8, 7.9) and 3.4 months (95% CI: 2.6, 4.1) for patients with and without evidence of MLFS, respectively. Median rwOS landmarked at 60 days after 1L initiation showed a similar trend, with a median rwOS of 26.9 months (95% CI: 19.4, 40.6) and 12.5 months (95% CI: 11.1, 15.5) for patients with and without evidence of MLFS, respectively.Conclusion: Bone marrow biopsies were available during 1L for a high proportion of the study population. Similarly, components to derive MLFS status were available for the large majority of biopsies. When focusing on biopsies occurring between 14 to 60 days after 1L initiation, complete information to ascertain MLFS status was available for at least one BM among all patients. In analyses with analytic endpoints, MLFS status was associated with longer rwTTNT and rwOS, in line with study hypotheses. Together, this information indicates a high degree of completeness in deriving MLFS using EHR data that may be used for analytic purposes. [Display omitted] DisclosuresGuinter: Flatiron Health, Inc.: Current Employment; Roche: Current equity holder in publicly-traded company. Kim: Flatiron Health, Inc.: Current Employment; Roche: Current equity holder in publicly-traded company. Jacob: Flatiron Health, Inc.: Current Employment; Roche: Current equity holder in publicly-traded company. Wise: Flatiron Health, Inc.: Current Employment; Roche: Current equity holder in publicly-traded company. Cha: Flatiron Health, Inc.: Current Employment; Roche: Current equity holder in publicly-traded company. Sawas: Affimed: Research Funding; Roche: Current equity holder in publicly-traded company; Flat Iron Health: Current Employment; Seattle Genetics: Honoraria; Gilead: Speakers Bureau; Acrotech: Honoraria; Daiichi-Sankyo: Speakers Bureau; Seattle Genetics: Speakers Bureau.

Sensitivity of Acute Myelocytic Leukemia Cells to the Dienone Compound VLX1570 Is Associated with Inhibition of the Ubiquitin-Proteasome System.

Dienone compounds with a 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have been widely reported to show tumor cell selectivity. These compounds target the ubiquitin-proteasome system (UPS), known to be essential for the viability of tumor cells. The induction of oxidative stress, depletion of glutathione, and induction of high-molecular-weight (HMW) complexes have also been reported. We here examined the response of acute myeloid leukemia (AML) cells to the dienone compound VLX1570. AML cells have relatively high protein turnover rates and have also been reported to be sensitive to depletion of reduced glutathione. We found AML cells of diverse cytogenetic backgrounds to be sensitive to VLX1570, with drug exposure resulting in an accumulation of ubiquitin complexes, induction of ER stress, and the loss of cell viability in a dose-dependent manner. Caspase activation was observed but was not required for the loss of cell viability. Glutathione depletion was also observed but did not correlate to VLX1570 sensitivity. Formation of HMW complexes occurred at higher concentrations of VLX1570 than those required for the loss of cell viability and was not enhanced by glutathione depletion. To study the effect of VLX1570 we developed a zebrafish PDX model of AML and confirmed antigrowth activity in vivo. Our results show that VLX1570 induces UPS inhibition in AML cells and encourage further work in developing compounds useful for cancer therapeutics.

Monocytic differentiation and AHR signaling as Primary Nodes of BET Inhibitor Response in Acute Myeloid Leukemia.

To understand mechanisms of response to BET inhibitors (BETi), we mined the Beat AML functional genomic dataset and performed genome-wide CRISPR screens on BETi- sensitive and BETi- resistant AML cells. Both strategies revealed regulators of monocytic differentiation, SPI1, JUNB, FOS, and aryl-hydrocarbon receptor signaling (AHR/ARNT), as determinants of BETi response. AHR activation synergized with BETi while inhibition antagonized BETi-mediated cytotoxicity. Consistent with BETi sensitivity dependence on monocytic differentiation, ex vivo sensitivity to BETi in primary AML patient samples correlated with higher expression of monocytic markers CSF1R, LILRs, and VCAN. In addition, HL-60 cell line differentiation enhanced its sensitivity to BETi. Further, screens to rescue BETi sensitivity identified BCL2 and CDK6 as druggable vulnerabilities. Finally, monocytic AML patient samples refractory to venetoclax ex vivo were significantly more sensitive to combined BETi + venetoclax. Together, our work highlights mechanisms that could predict BETi response and identifies combination strategies to overcome resistance.

A Genomic Signature Predicting Venetoclax Treatment Response in Acute Myeloid Leukemia (AML) Identified By Protein Network Mapping and Validated By Ex Vivo Ddrug Sensitivity Testing

A Genomic Signature Predicting Venetoclax Treatment Response in Acute Myeloid Leukemia (AML) Identified By Protein Network Mapping and Validated By Ex Vivo Ddrug Sensitivity Testing

Measurable residual disease response in acute myeloid leukemia treated with venetoclax and azacitidine.

7018 Background: In the phase 3 VIALE-A trial, rates of composite complete remission (CRc; complete remission [CR] + CR with incomplete hematologic recovery [CRi]) and measurable residual disease response (MRD<10-3) were higher in patients (pts) treated with venetoclax (Ven) + azacitidine (Aza) compared to Aza alone (23.4%/7.6%, p<0.001). There is limited evidence of the clinical significance of MRD monitoring in pts receiving low-intensity chemotherapy. Herein, we explored the outcomes of pts treated with Ven+Aza who achieved both CRc and MRD<10-3 in the VIALE-A trial (NCT02993523). Methods: Enrolled pts were ≥18 years and unfit for intensive chemotherapy. Pts received Ven 400 mg orally; days 1–28 and Aza 75 mg/m2; days 1-7/28-day cycle. Bone marrow aspirate samples for multiparametric flow cytometry assessments by integrated leukemia-associated immunophenotypes and different than normal procedures were collected for central analysis (Covance Central Laboratory Services) at baseline, end of cycle 1, and every 3 cycles thereafter. Assessments were performed independent of disease responses. MRD response was defined as <1 residual blast /1000 leukocytes (<10-3). CRc, DoR, OS, and EFS were assessed. Disease assessments were per modified International Working Group response criteria for AML. Results: 211/286 (74%) pts treated with Ven+Aza with at least one valid post-baseline MRD assessment were considered MRD evaluable; 78/211 (37%) achieved MRD<10-3 and 133/211 (63%) had MRD≥10-3. Median age (MRD<10-3/ MRD≥10-3) was 76 (range: 49-89)/77 (58-91) yrs. Pts (MRD<10-3/ MRD≥10-3) received median of 14.5 (range: 1-28) /7.0 (1-30) cycles of Ven+Aza. At median follow-up of 22.0 (range: 20.1-23.0)/20.8 (19.8-22.3) months (mos), CRc + MRD<10-3/ MRD≥10-3 was achieved by 67 (86%)/ 97 (73%); 20/67 (30%) achieved CRc + MRD<10-3 by end of cycle 1. Median DoR, OS, and EFS were not reached in pts with CRc + MRD<10-3 response (Table). The 12-mo estimates for DoR, OS, and EFS for pts with CRc + MRD<10-3response were 81.2%, 94.0%, and 83.2%, respectively. Adverse events ≥grade 3 (MRD<10-3/ MRD≥10-3) were febrile neutropenia (50%/43%), neutropenia (50%/35%), and thrombocytopenia (44%/44%), similar to the overall population. Conclusions: Pts with best response of CRc who achieved MRD<10-3 response with Ven+Aza treatment had longer DoR, OS, and EFS than pts who were CRc and MRD positive. Clinical trial information: NCT02993523. [Table: see text]

P53 Protein Isoform Profiles in AML: Correlation with Distinct Differentiation Stages and Response to Epigenetic Differentiation Therapy.

p53 protein isoform expression has been found to correlate with prognosis and chemotherapy response in acute myeloid leukemia (AML). We aimed to investigate how p53 protein isoforms are modulated during epigenetic differentiation therapy in AML, and if p53 isoform expression could be a potential biomarker for predicting a response to this treatment. p53 full-length (FL), p53β and p53γ protein isoforms were analyzed by 1D and 2D gel immunoblots in AML cell lines, primary AML cells from untreated patients and AML cells from patients before and after treatment with valproic acid (VPA), all-trans retinoic acid (ATRA) and theophylline. Furthermore, global gene expression profiling analysis was performed on samples from the clinical protocol. Correlation analyses were performed between p53 protein isoform expression and in vitro VPA sensitivity and FAB (French–American–British) class in primary AML cells. The results show downregulation of p53β/γ and upregulation of p53FL in AML cell lines treated with VPA, and in some of the patients treated with differentiation therapy. p53FL positively correlated with in vitro VPA sensitivity and the FAB class of AML, while p53β/γ isoforms negatively correlated with the same. Our results indicate that p53 protein isoforms are modulated by and may predict sensitivity to differentiation therapy in AML.

Increased frequency of TIGIT+CD73-CD8+ T cells with a TOX+ TCF-1low profile in patients with newly diagnosed and relapsed AML

ABSTRACT The inhibitory receptor TIGIT, as well as theectonucleotidases CD39 and CD73 constitute potential exhaustion markers for T cells. Detailed analysis of these markers can shed light into dysregulation of the T-cell response in acute myeloid leukemia (AML) and will help to identify potential therapeutic targets. The phenotype and expression of transcription factors was assessed on different T-cell populations derived from peripheral blood (PB, n = 38) and bone marrow (BM, n = 43). PB and BM from patients with AML diagnosis, in remission and at relapse were compared with PB from healthy volunteers (HD) (n = 12) using multiparameter flow cytometry. An increased frequency of terminally differentiated (CD45R−CCR7−)CD8+ T cells was detected in PB and BM regardless of the disease state. Moreover, we detected an increased frequency of two distinct T-cell populations characterized by the co-expression of PD-1 or CD39 on TIGIT+CD73−CD8+ T cells in newly diagnosed and relapsed AML in comparison to HDs. In contrast to the PD-1+TIGIT+CD73−CD8+ T-cell population, the frequency of CD39+TIGIT+CD73−CD8+ T cells was normalized in remission. PD-1+- and CD39+TIGIT+CD73−CD8+ T cells exhibited additional features of exhaustion by decreased expression of CD127 and TCF-1 and increased intracellular expression of the transcription factor TOX. CD8+ T cells in AML exhibit a key signature of two subpopulations, PD-1+TOX+TIGIT+CD73−CD8+- and CD39+TOX+TIGIT+CD73−CD8+ T cells that were increased at different stages of the disease. These results provide a rationale to analyze TIGIT blockade in combination with inhibition of the purinergic signaling and depletion of TOX to improve T-cell mediated cytotoxicity in AML. Abbreviations: AML: Acute myeloid leukemia; pAML: newly diagnosed AML; rAML: relapse AML; lrAML: AML in remission; HD: healthy donor; PB: peripheral blood; BM: bone marrow; TIGIT: T-cell immunoreceptor with Ig and ITIM domains; PD-1: Programmed cell death protein 1; CD73: ecto-5′-nucleotidase; CD39: ectonucleoside triphosphate diphosphohydrolase 1; ATP: adenosine triphosphate; ADO: adenosine; CD127: interleukin-7 receptor; CAR-T cell: chimeric antigen receptor T cell; TCF-1: transcription factor T-cell factor 1; TOX: Thymocyte selection-associated high mobility group box protein; NFAT: nuclear factor of activated T cells; NA: Naïve; CM: Central Memory; EM Effector Memory; EMRA: Terminal Effector Memory cells; FMO: Fluorescence minus one; PVR: poliovirus receptor; PVRL2: poliovirus receptor-related 2; IFN-γ: Interferon-γ; IL-2: interleukin-2; MCF: multiparametric flow cytometry; TNFα: Tumornekrosefaktor α; RT: room temperature.

Targeting of PI3K/AKT signaling and DNA damage response in acute myeloid leukemia: a novel therapeutic strategy to boost chemotherapy response and overcome resistance.

Resistance of cancer patients to DNA damaging radiation therapy and chemotherapy remains a major problem in the clinic. The current review discusses the molecular mechanisms of therapy resistance in acute myeloid leukemia (AML) conferred by cooperative chemotherapy-induced DNA damage response (DDR) and mutational activation of PI3K/AKT signaling. In addition, strategies to overcome resistance are discussed, with particular focus on studies underpinning the vast potential of therapies combining standard chemotherapy AML regimens with small molecule inhibitors targeting key regulatory hubs at the interface of DDR and oncogenic signaling pathways.

Magnesium levels and outcome after allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia

Low intake of magnesium has been associated with the occurrence of lymphomas and decreased magnesium levels suppress the cytotoxic function of T cells and natural killer cells in patients with “X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia” (XMEN) syndrome. These cell types are also important mediators of immune-mediated effects after allogeneic hematopoietic stem cell transplantation. Here, we show that high posttransplant magnesium levels independently associate with a lower incidence of relapse, a higher risk of acute graft-versus-host disease, and a higher non-relapse mortality in 368 patients with acute myeloid leukemia from our center. Magnesium serum levels might impact on donor-cell-mediated immune responses in acute myeloid leukemia.

Mitochondria in Their Prime Drive Venetoclax Response in Acute Myeloid Leukemia

Venetoclax has changed the clinical outlook for elderly and unfit patients with acute myeloid leukemia, but development of resistance is a challenge. In this issue of Cancer Cell, Bhatt etal. provide a general mechanism for how resistance emerges but also indications for how venetoclax-resistant cases may be treated.

“Triple” Combination of Targeting Methyltransferase, BCL-2 and PD-1 Facilitates Therapeutic Responses in Acute Myeloid Leukemia (AML)

“Triple” Combination of Targeting Methyltransferase, BCL-2 and PD-1 Facilitates Therapeutic Responses in Acute Myeloid Leukemia (AML)

Early Assessment of Treatment Response in Acute Myeloid Leukemia Using FLT PET/CT Imaging: A Trial of the ECOG-ACRIN Cancer Research Group (EAI141)

Introduction: Patients with acute myeloid leukemia (AML) are often treated with intensive induction chemotherapy to achieve complete remission (CR). Early response to standard anthracycline plus cytarabine induction (7+3) is assessed by a day 14 nadir bone marrow biopsy. The nadir marrow has limitations, though, including sampling issues and ambiguity as to whether blasts are leukemia cells vs. regenerating marrow. In prior studies, the predictive value for remission of the nadir marrow is only 67-84%. A more accurate predictor of residual disease (RD) would give clinicians an opportunity to modify therapy earlier. Positron emission tomography (PET/CT) with 3'-deoxy-3'-[18F]fluorothymidine (FLT) is a molecular imaging modality that can assess cellular proliferation in the bone marrow compartment. A prior single-institution pilot study showed a significant difference in the marrow FLT uptake between patients with AML who achieved CR and those who had RD after count recovery. Methods: EAI141 was an ECOG-ACRIN-led, prospective, multi-center study designed to assess FLT PET/CT as a predictor of CR after AML induction. The primary objective was to evaluate the predictive value of post-treatment FLT PET/CT imaging for detecting RD, with the secondary objectives of evaluating the predictive value for detecting CR and estimating the sensitivity and specificity. Maximum standardized uptake value (SUVmax) of > 7 g/mL in total bone marrow compartment was chosen prospectively based on data from a pilot study as a marker for presence of leukemia cells at nadir. The predictive values, sensitivity, and specificity of the FLT PET/CT and the nadir bone marrow biopsy were calculated. Eligible subjects were 18 years or older with previously untreated AML who were to receive induction with 7+3. Subjects underwent a nadir marrow biopsy and an FLT PET/CT scan 10-17 days after starting induction, and prior to any re-induction if disease was noted on the nadir marrow. A recovery marrow was performed 28-35 days after initial treatment or re-induction to assess CR or RD. Subjects could undergo an optional pre-treatment scan. Relapse-free survival (RFS) and overall survival (OS) were additional clinical outcomes. Results: 87 subjects from 9 centers were enrolled between 2016-2018, and 61 were considered evaluable. Reasons for being not evaluable included study ineligibility (n=3), no post-treatment scan (n=13), and no remission marrow (n=10). Median age was 58 years (range 21-73); 56% were men and 44% were women. CR was achieved in 56% (34/61). Treatment was a single induction course in 79% (48/61) and re-induction in 21% (13/61). Predictive value based on FLT PET/CT was 60% (9/15, 95% CI 32%-84%) for RD and 61% (28/46, 95% CI 45%-75%) for CR. Of patients who achieved CR, 28/34 had SUVmax ≤ 7 g/mL (sensitivity of 82%) and 9/27 of those who did not had high SUVmax > 7 g/mL (specificity 33%). Predictive value of an aplastic marrow was 59% (26/44) for CR and 56% (9/16) for RD. Of patients who achieved CR, 26/33 had marrow hypoplasia (sensitivity 79%) and 9/27 with RD had disease in the nadir marrow (specificity 33%). Significant heterogeneity of bone marrow compartment post treatment (SUVhetero ranging from 0.24 to 1.07) was observed in FLT-PET/CT scans. Heterogeneity of bone marrow compartment decreased about 50% from pre-treatment to post-treatment FLT PET/CT. OS for all participants, stratified by post-treatment FLT PET/CT response and nadir marrow results, are summarized in the Figure. Conclusions: Although this study did not show significant advantage of FLT PET/CT compared to nadir marrow to predict RD or CR on the average, it did show signal heterogeneity in the study population that may be relevant to disease biology not appreciated by a single sampling site for the nadir or remission marrow. For example, in patients with false negative nadir biopsy, in approximately 20% of patients assessment with FLT PET/CT was correct, likely reflecting bone marrow heterogeneity and limitation of a single point sampling. Similarly, in almost 60% of patients with false positive nadir biopsy, FLT PET/CT assessment was correct. Figure 1 Disclosures Jeraj: AIQ Solutions: Current equity holder in private company. Kostakoglu:F. Hoffmann-La Roche: Consultancy. Strickland:KiTE: Consultancy; Kura: Consultancy; Astellas: Consultancy; Jazz: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Sunesis: Research Funding; ArcherDx: Consultancy; AbbVie: Consultancy. Uy:Daiichi Sankyo: Consultancy; Pfizer: Consultancy; Agios: Consultancy; Genentech: Consultancy; Jazz Pharmaceuticals: Consultancy; Astellas Pharma: Honoraria. Perlman:GE Healthcare: Research Funding; AIQ: Research Funding.

Monosomy 7 and Co-Occurrent Genomic Aberrations Determine Chemotherapy Response in Acute Myeloid Leukemia (AML) Patients Using the Cellworks Omics Biology Model (CBM): Mycare-021-04

Background: Monosomy 7/Del 7 (-7) or its long arm (del(7q)) is one of the most common cytogenetic abnormalities in pediatric and adult myeloid malignancies, particularly in adverse-risk acute myeloid leukemias (AMLs). In general, (-7) is associated with poor response to induction chemotherapy (PMID 12393746). At the same time, not all patients fare poorly so the ability to identify responders and non-responders remains a high priority. Aim: To predict the response for induction chemotherapy in AML patients with (-7) and identify novel genomic signatures of response and resistance. Methods: Genomic data from 13 consecutive patients with (-7) were analyzed using the Cellworks Omics Biology Model (CBM) to generate patient-specific protein network models. All data was anonymized, de-identified and exempt from IRB review. For each model, disease simulations were performed and patients were segregated into HOXA-upregulated and HOXA-downregulated cohorts based on the simulation levels of HOXA5 and HOXA9. Digital drug simulations for induction chemotherapy were accomplished by measuring the impact of drug effect on a cell growth score, a composite of cell proliferation, viability and apoptosis indices. Each patient-specific model was analyzed to identify mechanisms underlying treatment outcomes. Results: 7/13 (54%) of (-7) patients failed to achieve remission after induction chemotherapy (Table 1) which highlighted that (-7) alone does not confer resistance to chemotherapy. CBM identified other genomic alterations that determine chemotherapy response, including DNA repair deficiency genes, mismatch repair (MMR), and homologous recombination repair (HRR) genes. DNA methylation and histone methylation (H3K27me) impacting HOXA gene expression, mainly HOXA5 and HOXA9, were identified as upstream regulators of DNA repair genes. Loss or reduced levels of EZH2 is associated with lower H3K27 methylation and thereby higher expression of HOXA5 and HOXA9 gene targets. High active levels of HOXA correlated with low rates of successful remission induction (22%, n=7) and lower activity levels of HOXA correlated with successful induction chemotherapy (100%, n=4) (Table 1). CBM identified that (-7) results in a decreased expression of EZH2, CARD11, EIF3, PMS2, HUS1, KMT2C (MLL3), CDK5 and IKZF1 genes. Since EZH2 abnormalities alone are not implicated in poor prognosis for AML patients, we sought other aberrations that prevent HOXA upregulation. Using CBM, we identified multiple accompanying aberrations which regulate HOXA genes. Deletions of KAT6A, ASXL1, DNMT3B, DNMT3L genes and high KMT2A-partial tandem duplication correspond to HOXA-upregulation whereas EED amplification, gain of function mutations in DNMT3A, mutations in IDH1/2, MYC and KAT6A amplification and KDM4A deletion result in HOXA-downregulation. Conclusion: Alterations of chromatin regulation have consequences for transcription factors that regulate expression of DNA repair genes. Under conditions where DNA repair is enhanced, induction chemotherapy was 78% less likely to effect remission in (-7) AML patients undergoing induction chemotherapy. Loss of H3K27 methylation associated with loss of PRC2 function by any means resulted in HOXA-upregulation and upregulation of DNA repair genes induced resistance to induction therapy. On the other hand, CBM analysis identified genetic signatures associated with a 100% remission rate from AML induction therapy despite the presence of (-7). Generation of H3K27me caused by PRC2 activation resulting from numerous mechanisms led to HOXA-downregulation and 100% response to induction therapy. Stratification of patients harboring (-7) by HOXA biomarker analysis could inform treatment planning, avoid drug-related adverse events and reduce treatment costs after validation with a larger prospective dataset. Disclosures Castro: Cellworks Group Inc: Consultancy. Watson:Cellworks Group Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cellmax Life Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mercy Bioanalytics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; SEER Biosciences, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; BioAI Health Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Kumar:Cellworks Research India Private Limited: Current Employment. Nair:Cellworks Research India Private Limited: Current Employment. Grover:Cellworks Research India Private Limited: Current Employment. Sahu:Cellworks Research India Private Limited: Current Employment. Mohapatra:Cellworks Research India Private Limited: Current Employment. G:Cellworks Research India Private Limited: Current Employment. Agarwal:Cellworks Research India Private Limited: Current Employment. Suseela:Cellworks Research India Private Limited: Current Employment. Ganesh:Cellworks Research India Private Limited: Current Employment. Sauban:Cellworks Research India Private Limited: Current Employment. Kumar:Cellworks Research India Private Limited: Current Employment. Raman:Cellworks Research India Private Limited: Current Employment. Singh:Cellworks Research India Private Limited: Current Employment. Basu:Cellworks Research India Private Limited: Current Employment. Lunkad:Cellworks Research India Private Limited: Current Employment. Mundkur:Cellworks Group Inc.: Current Employment. Macpherson:Cellworks Group Inc.: Current Employment. Kapoor:Cellworks Research India Private Limited: Current Employment. Howard:Servier: Consultancy, Other: Speaker; Boston Scientific: Consultancy; Sanofi: Consultancy, Other: Speaker; EUSA Pharma: Consultancy; Cellworks: Consultancy.

Flotetuzumab As Salvage Therapy for Primary Induction Failure and Early Relapse Acute Myeloid Leukemia

Flotetuzumab As Salvage Therapy for Primary Induction Failure and Early Relapse Acute Myeloid Leukemia