Low-dose Ara-C Research Articles

PICALM::MLLT10 may indicate a new subgroup of acute leukemias with miscellaneous immunophenotype and poor initial treatment response but showing sensitivity to venetoclax.

The PICALM::MLLT10 fusion gene is a rare but recurrent event in acute leukemia (AL) associated with poor prognosis. It is still confused whether PICALM::MLLT10 can solely correspond to acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) or acute leukemias of ambiguous lineage (ALAL). Here, we reported a series of PICALM::MLLT10 positive AL patients with miscellaneous immunophenotype including T-ALL, ALAL, AML, and B-ALL, complex karyotype, half of extramedullary disease (EMD), frequently concomitant PHF6 mutation, and poor initial treatment response to standard chemotherapy aiming to different immunophenotype, but showing sensitivity to combining chemotherapy especially integrated with venetoclax, suggesting this fusion gene may indicate a new subgroup of AL. Eighteen PICALM::MLLT10 positive patients of 533 AL patients (18/533, 3.4%) were identified by RNA sequencing in our center. We found PICALM::MLLT10 positive AL showing miscellaneous immunophenotype, higher expression of leukemic stemness genes and lower expression of biomarkers of venetoclax resistance, more extramedullary involvement, and especially poor response to conventional induction chemotherapy, but may benefit from venetoclax as well as low-dose Ara-C, granulocyte colony-stimulating factor (G-CSF), and anthracyclines combination chemotherapy. Sequential hematopoietic stem cell transplantation (HSCT) after chemotherapy combined with venetoclax may further improve long-term survival in AL patients with complete remission (CR) even measurable residual disease (MRD) positive.

Acute Myeloid Leukemia in Elderly, Unfit Patients: Analysis of Turkish AML Prospective Registry Database, on Behalf of Acute Leukemia Working Group of Turkish Society of Hematology

Objective: Low dose Ara-C and hypomethylating agents (HMAs) - decitabine (DEC) and azacitidine (AZA) - have made it possible to treat more elderly patients with acute myeloid leukemia (AML). Both HMAs demonstrated efficacy in monotherapy and in combination with targeted therapies. We analyzed the outcomes of elderly and unfit patients with newly diagnosed AML in our population. Methods: Analyses of our database revealed 222 eligible AML patients from diagnosed between January 2013 to December 2020. All patients were received low intensity treatments including AZA +/- venetoclax, DEC and low dose Ara-C. The effects of cytogenetic risk group, response rate, treatment type on overall survival (OS) and PFS (progression-free survival) were evaluated. Survival analyses were performed with the Kaplan-Meier method and log-rank test. A p-value of <0.05 was considered statistically significant. Results: Median age was 73 years (51-89). Eastern Cooperative Oncology Group (ECOG) performance score was <2 and ≥2 for 75 patients (36.8%) and 147 patients (63.2%), respectively. Of the patients 8.2% had favorable, 76.9% intermediate and 15.0% adverse risk according to European Leukemia Network (ELN) risk classification. Extramedullary involvement was present in 4.5%. Low dose treatment regimens included AZA in 119 patients (53.6%), DEC in 38 (17.6%), low dose ARA-C in 26 (11.7%) and AZA + venetoclax in 39 (17.1%). Complete remission was achieved in 61 patients (27.5%), whereas 39 patients (17.6%) had partial remission (PR) and 64 (28.8%) had stable/progressive disease (SD/PD). Overall response rate was 48.1%. CR rate was higher with AZA + venetoclax (44.7%, p=0,005) and other regimens had similar outcomes. Median OS was 10.3 months. No significant difference difference in PFS was observed between the regimens. However, the lowest PFS was observed with low-dose Ara-C (p=0.33). ELN risk groups revealed no significant effect on PFS and OS (p=0.77 and p=0.82, respectively). Infections were the most common cause of death (42.7%). Conclusions: The prognosis of AML in the elderly remains poor. HMA monotherapy is effective among elderly and unfit patients. However, combination therapies may be more effective and safe. The incorporation of targeted therapies may provide additional benefit in this patient group. However, the accessibility of several novel targeted drugs is still very limited in many countries.

The Signaling Pathways Enriched in High-Risk AML Patients Revealed By the Integrative miRNA-mRNA Analysis - Pilot Study

Introduction Acute myeloid leukemia (AML) is highly heterogeneous disease with broad spectrum of mechanisms involved in pathogenesis. The unique microenvironment of hematopoietic niche (HN) consists of several proteins with corresponding receptors on normal and leukemic cells. The interactions within HN include ligand-receptor pairs as SDF-1/CXCR4; OPN/CD44; Jagged-1/Notch-1; ANG-1/Tie-2 and Slit2/Robo4. MicroRNAs (miRNAs) are small noncoding RNA molecules that post-transcriptionally modulate gene expression by binding to targeted mRNAs. The dysregulation of ligand-receptor interactions by miRNAs could disrupt the niche's equilibrium and may contribute to the establishment of a leukemic burden and progression of AML. In our study we aimed to explore the clinical impact of miRNAs profile in the context of the mRNA genes expression involved in ligand-receptors interactions in the bone marrow of newly diagnosed AML patients (pts). Methods The expression of 12 mature miRNAs: miR-15a-5p, miR-34a-5p, miR-125b-5p, miR-139-5p, miR-146-5p, miR-181a-5p, miR-199b-5p, miR-204-5p, miR-218-5p, miR-299-5p, miR-424-3p, miR-452-5p was determined in duplicates in bone marrow samples of de novo AML pts using real-time PCR. The miRNAs expression was normalized using the mean expression of all miRNAs in a given sample. The expression assessment of 10 following genes: CXLC12 (coding SDF-1 ), CXCR4, NOTCH1, JAG1 (coding Jagged-1), SPP1 (coding osteopontin) , CD44, SLIT2, ROBO4, ANGPT1 (coding angiopoietin-1) , TEK (coding Tie-2 receptor) was performed in the bone marrow at the time of AML diagnosis. The gene expression was determined in duplicates by real-time PCR using the QuantStudio 7 (Applied Biosystems-ThermoFisher Scientific). Gene expression was normalized using selected reference genes ( MRPL19 and PPIA). Differential expression analysis was conducted using a heteroscedastic t-test, volcano plots were used to visualize results. Using significantly deregulated miRNAs and genes in high-risk AML, OmicsNet (https://www.omicsnet.ca) was used to create miRNA-mRNA biological network. For network creation, protein-protein interactions (STRING) and miRNA-mRNA (TarBase) databases were used. Further, a pathway enrichment analysis was performed using Reactome database. Results The study group consisted of 28 (16 women and 12 men) newly diagnosed AML adults with the mean age 57.7 ± 12.8 years. Among them, 14.3% pts had a low-risk, 39.3.% intermediate-risk and 39.3% high-risk AML according to European LeukemiaNet ( ELN) 2022 risk stratification. In 2 pts molecular data was not available. The most common subtype was AML not otherwise specified (11 pts, 39.3%), followed by AML with myelodysplasia-related cytogenetic abnormality (6 pts, 21.4%), AML with myelodysplasia-related gene mutation (5 pts, 17.9%), and AML with recurrent genetic abnormality (4 pts, 14.3%). At diagnosis the median white blood cell count was 26.7 × 10 9/L (interquartile range, IQR: 3.0 - 73.1 × 10 9/L), the median bone marrow blasts was 63.0% (IQR: 41.0- 88.3) and the median lactate dehydrogenase (LDH) level was 532.5 U/L (IQR: 284.0-986.5). The majority of pts (86%) received intensive chemotherapy according to Polish Adult Leukemia Group (PALG) protocols. In FLT3 mutated pts standard induction/consolidation therapy was enriched with midostaurin. Low intensity treatment consisted of azacitidine (1 pts), low dose Ara-C (LDAra-C, 2 pts) and LDAra-C + cladribine (1 pts). Patients with high-risk AML had higher expression of miR-125b-5p (fold change- FC=2.3, p=0.017) and lower expression of miR-15a-5p (FC=0.6, p=0.043) as compared to low- and intermediate-risk pts. Similarly, two genes were significantly upregulated in ELN high-risk group - TEK (FC=4.1, p=0.017) and SPP1 (FC=6.7, p=0.041). OmicsNet was used to construct miRNA-gene interaction networks between miR-125b-5p, miR-15a-5p, TEK, SPP1 and other miRNAs target genes. In final multi-omic network, 6 miRNAs and 50 mRNA/proteins were included (Figure 1). We found that the pathways of PDGF, NGF, FGFR, PI3K, IGF1R and EGFR signaling are significantly enriched in high-risk AML patients. Conclusions Our preliminary results indicate the signaling pathways disturbed in high-risk AML patients. The miR-125b-5p, miR-15a-5p as well as the TEK and SPP1 gene expression may possibly act as biomarkers in patients with de novo AML.

Data-Driven Multiparameter Flow Cytometry (MFC) Classification of Blast Differentiation in Elderly Patients with Acute Myeloid Leukemia (AML)

Background: The identification of the nearest normal counterpart of blasts has been part of the patients' diagnostic workup and contributed to the sub-classification of AML. While there is a progressive displacement of morphologically defined AML subtypes by those with recurrent genetic abnormalities, recent studies in younger patients eligible for intensive chemotherapy suggested that a phenotypic sub-classification of AML might be prognostic. However, an antigen-based assessment of blast differentiation is in part complex and subjective, and to our knowledge has not been systematically investigated in elderly AML. Aim: Develop a data-driven approach to facilitate and systematize the phenotypic dissection of older AML patients ineligible to receive intensive chemotherapy. Methods: The study included 252 patients (>65yo) that were randomized to azacitidine vs low-dose Ara-C plus fludarabine in the PETHEMA-FLUGAZA trial. MFC was performed using the EuroFlow AML panel in bone marrow aspirates. The percentage of expression of each marker in hematopoietic progenitor cells (HPC), granulocytic, monocytic and erythroid precursors, as well as in maturing granulocytes, monocytes and nucleated red blood cells (NRBC) was determined in 15 healthy adults. The data were merged and a matrix was obtained for each subject. The percentage of expression of each marker was determined in patients' blasts. After projecting each case onto the matrix generated from healthy adults, the distance between blasts and normal populations was calculated, and the shortest distance identified the corresponding differentiation stage. Blasts were isolated according to patient-specific aberrant phenotypes for DNA and RNA co-isolation and subsequent next-generation sequencing (n=179/252) and RNA-seq (n=190/252). Results: Of the 252 patients, 64% were classified with an HPC-like AML phenotype, 27% a granulocytic-precursor, 2% monocytic-precursor, 2% erythroid-precursors, <1% maturing-granulocytic, 4% maturing-monocytic and <1% maturing-NRBC. Cell types from the same lineage were regrouped into granulocytic-, monocytic and erythroid-like AML. Overall, there was a 46% concordance between phenotypic and FAB classification. Interestingly, patients classified as HPC-like AML treated with azacitidine (and not those receiving semi-intensive chemotherapy) showed slightly longer overall survival when compared to those with maturing AML subtypes. We next investigated the relationship between phenotypically-defined stages of blast arrest and the presence of underlying mutations. Interestingly, there was scarce overlap in the top three recurrently mutated genes across the HPC- ( SRSF2, TET2, RUNX1), granulocytic- ( ASXL1, FLT3, TET2), monocytic ( FLT3, NF1, TET2), and erythroid-like ( TP53, DNMT3A, NF1) AML subtypes. Conversely, EPAS1, FLT3 and NF1 were more frequently mutated ( p<.05) in erythroid- and monocytic- vs HPC-like AML. Amongst the maturing subtypes, monocytic-like AML was characterized by frequent SH2B3 and absent TP53 mutations ( p<.05). The comparison between HPC-like vs all maturing subtypes identified several deregulated genes associated with different stages of hematopoiesis (i.e., HOXA3, ANKRD28, CLEC2B, HSD17B11, SYPL1, HBD, S100A8, ITGAM). Granulocytic-like AML patients showed deregulation of 200 genes; 44 of which were upregulated and enriched in granulocytic-related pathways. Only 23 genes were deregulated upon comparing the transcriptional profile of HPC- vs monocytic-like blasts. A total of 415 genes were deregulated between HPC- and erythroid-like blats; 269 of which being overexpressed and associated with pathways such as transferrin transport, erythrocyte development and differentiation. Accordingly, the transcriptional profile of blasts corroborated our data-driven approach. Conclusions: This study builds upon recent interest in non-genetic drivers of AML heterogeneity and classification systems based on the partial recapitulation of myeloid development, and shows that these concepts may be applied in elderly patients. Our proof-of-concept data-driven approach has the potential to be incorporated into flow cytometry analytical software towards a more objective dissection of AML subtypes based on blast differentiation, which could potentially yield prognostic information complementary to other routine diagnostic procedures.

Down Syndrome with Acute Myeloid Leukemia in an Adolescent Male Successfully Treated with Low Dose Ara-C in Combination with Hypomethylating Agent

Introduction Patients with Down syndrome (DS) are prone to developing hematological malignancies, with risk of acute myeloid leukemia (AML) being 150 -fold higher compared to the general population. DS patients with leukemia are likely to experience significant chemotherapy related toxicities, hence require dose modifications. The myeloid leukemia of Down Syndrome (ML-DS) typically reflects acute megakaryoblastic leukemia (AMKL) a rare subtype of AML. ML-DS typically evolves from transient aberrant/abnormal myelopoiesis (TAM), aka transient myeloproliferative disorder (TMD), a pre-leukemic syndrome that almost always precedes myeloid leukemia in Down syndrome. GATA1, the hallmark driver mutation of TAM, is found in all TMD/TAM cases. AML in DS can occur de-novo which represents a different entity, appears immunophenotypically as (non-AMKL) AML, but differs morphologically from the classical ML-DS. The de-novo type AML in DS is reported to have worse prognosis. Poor outcomes are due to increased chemosensitivity and resulting chemotherapy-related toxicities when treated on standard high dose Ara-C based AML regimens. There is currently a lack of consensus on standard-of-care AML therapy applicable to this population. Methods Case report, retrospective electronic medical record review with institutional board review exemption Results We report a case of a 25-year-old male with trisomy 21, presenting with a one-month history of low-grade fevers, fatigue, and upper back pain. Initial laboratories showed a white cell count of 6.6 K/uL, hemoglobin 11.9 gm/dL, platelets 352 K/uL. CT chest showed a large right-sided pleural effusion, pleural thickening and multiple sclerotic bone lesions concerning for malignancy. Positron emission tomography (PET) CT revealed multiple hypermetabolic foci in the pelvis, spine, ribs, and cervical lymph nodes. Thoracocentesis was completed and pleural fluid pathology revealed atypical cells, flow cytometry showed 18% blasts positive for CD38, CD45, CD117 and negative for CD34 and HLA DR indicative of a myeloid neoplasm. Bone marrow aspirate and biopsy showed 10% CD117 positive immature myeloid cells. Morphology was not megakaryoblastic. Bone marrow flow cytometry results were consistent with that of pleural fluid with CD117 and myeloperoxidase (MPO) positive blasts. Fluorescent in-situ hybridization was negative for fusions/rearrangements. Next generation sequencing (NGS) detected NPM1 mutation and also a low level (variant allelic frequency <3%) FLT3 p.Y599C mutation (not internal tandem duplication or tyrosine kinase domain). GATA1 mutation was absent. A diagnosis of AML with NPM1 mutation and staging CNS1 was confirmed. Our patient was defined as DS and AML. Given innate fragility and higher chemo sensitivity in patients with DS, we elected to treat him off protocol with Cladribine and low dose Ara-C alternating with Decitabine. This regime was derived from an adult leukemia protocol. Cycle 1 was complicated by central line related occlusive thrombus requiring anticoagulation, slow count recovery, and a brief episode of febrile neutropenia managed with antibiotics. End of induction marrow evaluation was negative for minimal residual disease (MRD). Flow cytometry on pleural fluid was also negative for abnormal blasts that were previously detected. Repeat molecular testing with NGS was negative for NPM1, DNMT3A, and FLT3 mutations. The patient received a total of 8 cycles of chemotherapy. On subsequent bone marrow evaluations, blasts remained <5% and MRD was negative. Interval PET scan showed significant improvement. Patient is currently more than a year off therapy and remains in remission. Conclusion Patients with DS and AML have a higher mortality due to increased risk of cardiotoxicity and infection from chemotherapy. There is a risk of either undertreatment or less commonly overtreatment leading to early mortality. Our case describes an adolescent male with DS and AML with pulmonary comorbidity who was successfully treated with a low-dose Ara-C regimen adapted from an adult protocol and had great clinical outcome. AML treatment in DS remains a challenge and further research is warranted to develop tailored regimens effectively balancing curative intent and reduced toxicity. This regimen could be considered in pediatric patients with Down Syndrome and other comorbidities.

Cladribine and cytarabine in children refractory high risk multisystem Langerhans cell histiocytosis

There is no uniform regimen for refractory Langerhans cell histiocytosis (LCH). We retrospectively described patients with refractory multisystem and risk organ involvement LCH treated with the low-dose (Ara-c, 100 mg/m2/d × 5day; 2-CDA, 5 mg/m2/d × 5day) chemotherapy (LDC) and the intermediate-dose (Ara-c, 500 mg/m2/d × 5day; 2-CDA, 9 mg/m2/d × 5day) chemotherapy (IDC). 26 patients and 10 patients receiving the LDC and IDC regimen from January 2013 to December 2016 were included in the study. The overall response rate exhibited no significant difference between the LDC and IDC groups after four courses (76.9% vs 90%, P = 0.375) and eight courses (80.8% vs 100%, P = 0.135) of treatment. No statistical differences in the overall survival rate were observed between the two groups, but 5-year event-free survival rate of patients in the IDC group was higher than that in the LDC group at the median follow-up of 6.16 and 5.07 years (88.9% vs 52.9%, P = 0.033). The patients in the IDC group had more severe myelosuppression than those in the LDC group (grade 3/4 myelosuppression, 80% vs 19.2%, P = 0.001). The intermediate-dose regimen of 2CDA and Ara-c had a higher event-free survival rate and a similar overall survival rate compared with the low-dose regimen.

Rapid progression of left ventricular hypertrophy caused by leukaemic infiltration of myocardium.

A man in his 40s was hospitalized due to recurrence of acute myeloid leukaemia. Echocardiography was performed because of negative T waves in the electrocardiogram. Severe and global left ventricular hypertrophy (LVH) was observed (Panels B and E, see Supplementary data online, Video S2), which was not found 15 months ago (Panels A and D, Supplementary data online, Video S1). Computed tomography scan also showed severe LVH (Panel H), which was not found 3 months ago (Panel G). Thus, it was confirmed that the rapid hypertrophic change occurred within 3 months. Low-dose Ara-C (cytosine arabinoside) and VP-16 (etoposide) therapy was administered for leukaemia. Echocardiography, after two weeks from the start of treatment, showed reduced LVH (Panels C and F). Therefore, the myocardial infiltration of leukaemia cells was considered as the cause of LVH. Unfortunately, 16 weeks later, the patient died by multiple organ failure. Autopsy showed that the cardiac wall thickened and numerous numbers of leukaemia cells infiltrated in the myocardium (Panels J and K). Distribution of the myocardial fibre was disarrayed but necrosis was not found. Infiltration of leukaemia cells was observed in multiple organs.

Q-TWiST in Venetoclax-Based Regimens in Elderly Patients with AML: A Quality-Adjusted Analysis

Introduction: Non-intensive venetoclax-based regimens are the current standard of treatment for acute myeloid leukemia (AML) in the elderly. Phase 3 VIALE-C (LDAC vs. LDAC+Ven) and VIALE-A (Aza vs. Aza+Ven) trials showed improved median overall survival (OS) from 4.1 to 7.2 months (VIALE-C) and from 9.6 to 14.7 months (VIALE-A), with serious adverse events (SAEs) in 73% low-dose AraC (LDAC), 83% (Aza + Ven), 66% (LDAC + Ven). Quality of the time gained with these regimens is particularly important in this population. Q-TWiST is a useful tool to adjust the OS to quality time without symptoms or toxicity. This kind of analysis has been previously published in newly diagnosed AML in glasdegib + LDAC vs LDAC trials (Solem CT, 2020), and in the CPX-352 vs 7+3 (Cortes JE, 2021) trial. However, venetoclax-based non-intensive regimens have not been analyzed with this method. Methods: We performed a retrospective, longitudinal analysis of data gathered from a single-center cohort. All newly diagnosed, >60 years old patients with upfront management with venetoclax-based non-intensive chemotherapy combined with LDAC or hypomethylating agents (HMA) at our institution were included. TOX time was defined as the period of time before remission and/or time with serious adverse events (SAE) as defined by Office for Human Research Protections (OHRP) guidance (2007). REL time was defined as time from relapse until death, last follow-up or the start of a second line treatment, TWiST was defined as the time in remission and without SAEs. Q-TWiST analysis was performed as previously described (Solem CT, 2020). Results: We included 17 patients, 58.8% were male, mean age was 74 (70-78) years. The diagnosis was de novo AML in 52.9%, and secondary AML in 46.9%. European LeukemiaNet (ELN) risk was favorable in 5.8%, intermediate in 11.7% and adverse in 41.1%, 35.2% was unknown, FLT3-ITD mutations were present in 23.5%. 25% of the population had basal ECOG performance status ≥3, HCT-CI score was ≥3 in 47%. Considering the patients with baseline geriatric assessment: 14.2% were frail, 42.8% pre-frail and 42.8% robust. Venetoclax was combined with azacitidine in 35.2% and LDAC in 64.7%, 11.7% received additional midostaurin. Venetoclax dose was 100 mg/day in combination with strong CYP3A4 inhibitors (mainly itraconazole) in all patients. By last cycle, venetoclax was adjusted to <28 days in 76.6% of patients. Azacitidine dose was adjusted in 60% of patients, and LDAC in 9%. 76% of patients achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) with the treatment, 23.5% had no response and 28% relapsed. With a mean follow up of 42.4 (25.7-59.1), mean OS was 43.1 (95% IC 26.6-59.6), progression free survival (PFS) 37 (95% IC 19.1-54.8), Q-TWiST 36.3 (95% IC 19.7-53), and TWiST 30.3 (95% IC 13.5-47.1) weeks. Other variables related to toxicity are shown in table 1. Comparison with previously reported Q-TWiST with LDAC and 7+3 as frontline therapy in the elderly is described in Figure 1. Conclusions: the Q-TWiST in our unselected population was better than the Q-TWiST described for LDAC arm in the glasdegib trial, this is striking considering the comparison between real world data in a low-income setting with clinical trial population. This suggests that venetoclax-based non intensive chemotherapy not only offers longer OS but also longer quality-adjusted time compared to previous standard to this vulnerable population. When compared to 7+3 regimens the Q-TWiST was slightly shorter in our cohort,probably associated with the inclusion criteria of the trial, including ability to tolerate 7+3 regimen and an age limit of 75 years, which different from our population. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Prospective Phase 2 Study of Venetoclax and Low Dose Ara-C (VALDAC) to Target Rising Molecular Measurable Residual Disease and Early Relapse in Acute Myeloid Leukemia

Introduction The 2021 European LeukemiaNet (ELN) recognizes MRD relapse as ≥1 log rise confirmed on repeat testing (Heuser Blood 2021). Molecular MRD relapse (e.g. NPM1mut) precedes clinical relapse by ~3-4 months (Ivey NEJM 2016) and provides a window of opportunity for pre-emptive therapy to be delivered prior to clinical relapse. Venetoclax (VEN)-based low intensity therapy is associated with rapid achievement of clinical response in older patients (pts) with AML (DiNardo NEJM 2020 and Wei Blood 2020) but only has modest activity in relapsed/refractory AML. We hypothesized that VEN-based therapy initiated at the time of MRD relapse could be associated with improved clinical response and longer clinical benefit. We therefore conducted a prospective study to explore the efficacy of low dose ara-C (LDAC) + VEN in pts with AML and MRD relapse (ACTRN12619000746134). Methods This multicenter phase 2 study stratified pts into either oligoblastic relapse (marrow blasts 5-15%; Group A), or molecular MRD relapse (Group B). Pts received VEN 600 mg (days 1-28, without dose ramp-up for Group B) and LDAC 20 mg/m2 sc (days 1-10). Primary objectives were morphologic or MRD response (≥1 log reduction) in groups A and B, respectively. Key secondary objectives were realization of allogeneic hematopoietic cell transplantation (HCT), relapse-free (RFS) and overall survival (OS). The study was approved by Alfred Health ethics committee (196/19). NPM1mut and other fusions (per 100 ABL1) from bone marrow were analyzed by RT-qPCR, and IDH1/2mut by Bio-RadTM droplet digital PCR. Results A total of 48 pts were recruited (median age 67; range 18-80). Cytogenetic risk was intermediate in 91%, favorable in 4.5% and adverse in 4.5%. Most (94%) had received prior intensive chemotherapy and only 2 (4%) had received prior HCT in first remission. The median interval from AML diagnosis to study entry was 13.7 months (IQR 9, 23). At the time of study screening, 22 (46%) pts had oligoblastic disease and 26 (54%) MRD relapse. Oligoblastic relapse included pts with early progression not captured by interval MRD surveillance. Pts received a median of 3 cycles (range 1-21+) of VEN-LDAC (ongoing in 11). Reasons for treatment cessation in 37 pts were: HCT (n=19, 51%), treatment failure (n=11, 30%), adverse events (n=3), donor lymphocyte infusion (DLI, n=2) or death before response assessment (n=2). One patient (Group B, NPM1mut) was deemed not evaluable for response assessment after only receiving 9 days of therapy but included in the survival analysis. Among 22 pts with oligoblastic disease, CR/CRi was achieved in 17 (77%). Two additional pts achieved morphologic leukemia-free state and 1 had stable disease. MRD response (≥1 log reduction) among those with an evaluable marker (N=8; all NPM1 mutated) was achieved in 8/8 (100%), with MRD negative in 6/8 (75%) (Figure). Among 25 evaluable pts with MRD relapse, MRD response (≥1 log reduction) was observed in 68% and MRD negative in 52%. Of patients with NPM1mut AML treated at MRD relapse, 13/19 (68%) achieved an MRD response and 10/19 (53%) an MRD negative response (Figure). An MRD response was observed in 2/3 with IDH1/2mut, 1/2 with core-binding factor and 1/1 with KMT2A::MLLT3. Bridging to HCT or DLI (median time 4 months) was successful in 18/27 (67%) pts ≤70 years. With a median follow up time of 14.4 months, the median RFS was 21.5 months and not reached for OS. The estimated 18-month RFS was 63.3% (95% CI, 48.0-83.5) and OS 71.1% (95% CI, 56.5-89.4). Similar outcomes were observed for Groups A and B. Subsequent HCT (as a time-dependent covariate) was the only significant factor for RFS (HR 0.13, 95% CI 0.03-0.61) but not OS (HR 0.48, 95% CI 0.13-1.75) in a multivariate Cox regression model that included age, features at original diagnosis (NPM1, FLT3-ITD and ELN 2017 risk), time since AML diagnosis, and study cohort (A vs B). FLT3-ITD was detected in 3/7 (43%) of relapsed pts. Conclusions In this prospective study of pts with early relapsing AML (oligoblastic or MRD relapse), VEN in combination with LDAC induced a high rate of molecular MRD response, resulting in excellent RFS and OS outcomes. Follow-up is ongoing to determine the durability of response. This novel MRD-targeting approach is being further investigated in a multi-arm, precision-based platform trial ( INTERCEPT: Investigating Novel Therapy to Target Early Relapse and Clonal Evolution as Pre-emptive Therapy in AML; ACTRN12621001265864). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Venetoclax Added to Cladribine (CLAD) + Low Dose AraC (LDAC) Alternating with Azacitidine (AZA) Is Highly Active As Frontline Therapy in Older Patients with Newly Diagnosed Acute Myeloid Leukemia in a Phase 2 Study

Background The combination of venetoclax with AZA for patients with newly diagnosed AML who are older or unfit for intensive chemotherapy significantly improves remission rates and survival compared to AZA alone. A low-intensity backbone combining venetoclax with cladribine (CLAD) plus low-dose araC (LDAC) alternating with HMA has demonstrated encouraging results in older patients with newly diagnosed AML (Kadia TM, et al. J Clin Oncol. 2022). Here we report an updated cohort of patients with longer-term follow up treated on the phase 2 clinical trial of venetoclax added to CLAD/LDAC alternating with AZA. Methods This is a phase 2 study (NCT03586609) investigating the combination of venetoclax with CLAD/LDAC alternating with AZA in older (age ≥ 60 years) or patients <60 years that are unfit for intensive chemotherapy with newly diagnosed AML (excluding APL, CBF). The primary objective was composite complete response rate (CRc; CR+CRi); secondary endpoints were overall survival (OS), disease-free survival (DFS), overall response rate (ORR), and toxicity. Induction was with cladribine 5 mg/m2 IV on D1-5 and araC 20mg SQ BID on D1-10. Consolidation/maintenance consisted of 2 courses of cladribine 5 mg/m2 IV on D1-3 and araC 20 mg SQ BID on D1-10 alternating with 2 cycles of AZA 75 mg/m2 on D1-7, for up to 18 courses. Venetoclax 400 mg was added for each course with dose adjustments for concomitant CYP3A inhibitors. Venetoclax was given for 21 days during induction and for 7-14 days for consolidation depending on measurable residual disease (MRD) and tolerability. One cycle was 4 weeks and up to 2 cycles of induction were allowed. Results A total of 93 patients were treated on study with a median age was 68 years (range: 57 - 84); 28 (30%) patients were ≥ 70 yrs and 1 patient <60, unfit for intensive chemotherapy was enrolled. 29 (31%) patients had secondary or therapy related AML. 52 (56%) had diploid cytogenetics with 11 (12%) having adverse cytogenetics at enrollment. By European Leukemia Network (ELN) risk, 24%, 24%, and 53% were favorable, intermediate, and adverse risk, respectively. The most commonly mutated genes were DNMT3A in 28 (30%), NPM1 in 26 (28%), RAS in 23 (25%), TET2 in 22 (24%), and IDH2 in 20 (22%). TP53 was mutated in 8 (9%) patients. Among 93 evaluable patients the CRc rate was 92%. Best response was CR in 72 (78%), CRi in 13 (14%), no response in 5 (5%), and death in 2 (2%) patients. In responding patients with a bone marrow sample evaluable for assessment of MRD by flow cytometry, 71/85 (84%) achieved MRD negativity while on study. Responses were preserved across ELN risk groups with the CRc (CR/CRi) rate of 95% (86%/9%), 95% (82%/14%), and 90% (73%/17%) for patients with ELN favorable, intermediate, and adverse risk, respectively. CRc rate for TP53 mutated disease was 88% (7/8, 86% MRD negative) and for NPM1 mutated disease was 96% (25/26, 100% MRD negative). 35 (41%) responders received a subsequent allogeneic stem cell transplantation (alloSCT). Early mortality was low with two patients (2%) dying within 4 weeks and five patients (5%) dying with in 8 weeks. The most frequent grade 3/4 non-heme adverse events were febrile neutropenia (n=12), infection (n=7), atrial fibrillation (n=2), and allergic reaction (n=2). One patient developed grade 4 tumor lysis syndrome. With a median follow up of 22.8 months, the median duration of response (DOR) is not reached (95% CI: NE - NE months). Estimated 12- and 24-month DOR are 88.4% (95% CI: 81.0 - 96.4%) and 81.0% (95% CI: 71.0 - 92.4%), respectively. Median disease-free survival (DFS) is not yet reached (95% CI: 24.5 - NE months). Estimated 12- and 24-month DFS are 76.0% (95% CI: 66.8 - 86.4%) and 63.4% (95% CI: 52.1 - 77.1%), respectively. Median overall survival (OS) is not yet reached (95% CI: 25.4 - NE months). Estimated 12- and 24-month OS are 75.7% (95% CI: 66.9 - 85.7%) and 68.3% (95% CI: 58.1 - 80.1%), respectively (Figure). Conclusion Venetoclax added to CLAD/LDAC alternating with AZA is a highly effective, lower-intensity regimen which is well tolerated among older patients with newly diagnosed AML, producing high CRc and MRD negative remission rates and is effective in transitioning older adults to alloSCT. The rates of DFS and OS are encouraging. Further study of this non-anthracycline containing regimen is warranted in older patients both fit and unfit for intensive chemotherapy as a safe and effective induction treatment strategy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Application of the SORE6 Reporter in the Studies of Acute Myeloid Leukemia - a Novel Model for Disease Relapses

Most patients diagnosed with acute myeloid leukemia (AML) suffer from disease relapses within two years after the initial remission. Treatment options for relapsed AML are limited and the clinical outcome associated with this stage of disease is dismal. Partly due to the lack of experimental models, the biology underlying AML relapses is not well understood. We hypothesized that the cancer stem-like (CSL) cells, which represent a minority of the neoplastic cell population, are the major contributors of AML relapses. SORE6, a reporter designed to detect the expression and activity of inducible pluripotent stem cell factors, was used to identify/purify CSL cells in two FLT3-mutated AML cell lines, MOLM-13 and MV4-11. Both cell lines contained ~10% of SORE6+ cells at the steady state, as revealed by their expression of the reporter green fluorescence protein. Compared to SORE6- cells, SORE6+ cells had significantly more spheroid formation in the hanging drop assay (75 vs 35%, p=.006), and were significantly more resistant to Ara-C (inhibitory concentration at 50%, 60 vs 25 nM, p=.0005) and Venetoclax (2.6 vs 8.2 nM, p=.002) in the presence of low-dose Ara-C. By western blots, SORE6+ cells were found to express substantially higher levels of Myc/FLT3/pSTAT5 than SORE6- cells. Myc appeared to be a key driver of SORE6 activity, and the reporter activity was effectively suppressed by Myc pharmacologic inhibitors or shRNA. By subjecting a mixture of bar-coded SORE6- and SORE6+ MOLM-13 cells (in 9:1 ratio to mimic that at the steady state) to the lowest concentration of Ara-C that resulted in no detectable viability in the cell culture, we consistently found evidence of cell regeneration after 8-12 days of undetectable cell viability. Regeneration initially occurred slowly, and the cell growth went into a log phase after 1-2 weeks. Using PCR to detect the relative proportion of bar-coded SORE6- and SORE6+ cells, we found that the regenerated cell population contained a substantially higher proportion of SORE6+ cells, with 64% SORE6+ cells in the initial slow-growth phase. In comparison, the proportion of cells originating from SORE6+ cells increased to an average of 86% during the log-growth phase. Importantly, cells in the log-growth phase were found to have a significantly higher resistance to Ara-C and had significantly more spheroid formation in the hanging drop assay compared to untreated cells. To further validate the concept that CSL cells are the key contributors to the AML relapse, we collected pairs of initially diagnostic and relapsed bone marrow specimens derived from the same patients. By immunocytochemistry, we found that relapsed AML blasts were more frequently positive for Myc, a surrogate marker of SORE6 activity, compared to those in the pre-treatment samples. To conclude, using SORE6, we have developed a technically simple experimental model that capitulates some of the key features of AML relapses. Our model has provided direct evidence that CSL cells are key contributors to the disease relapse in AML. We believe that this in-vitro model is valuable in testing the efficacy of new therapeutic agents against AML, especially those designed to target the CSL cell population.

Personalization of Induction Therapy for Pediatric AML to Ara-C+Dauno+ Etoposide (ADE) or Clofarabine+Ara-C According to a Polygenic Ara-C SNP Score- ACS10

Acute myeloid leukemia (AML) is a heterogenous disease with overall suboptimal outcome. Although chemotherapy regimens that include cytarabine (ara-C) induce remission in a majority of pediatric AML patients, approximately 30% relapse and subsequently have very dismal outcome. Ara-C is a prodrug requiring activation to ara-CTP which induces leukemic cell death. Thus, inter-patient variation in each patient's ability to activate ara-C is a significant contributor to clinical outcomes. We recently performed a comprehensive pharmacogenomics evaluation of SNPs in ara-C metabolism pathway genes and developed a polygenic ara-C 10-SNP genotype (ACS10) score based on association with leukemic intracellular ara-CTP levels and clinical outcome (Elsayed et al, 2022, JCO1). Our results demonstrated that patients with low ACS10 score had poor outcomes when given standard induction including low-dose ara-C, daunorubicin and etoposide (ADE); however their outcomes were much better by augmenting therapy with either an increased dose of ara-C or the addition of gemtuzumab ozogamicin1. Conversely, patients with a high ACS10 score fared worse when given high-dose ara-C than low ara-C dose-based ADE induction (LDAC). These results suggest that pediatric AML patients may benefit from pharmacogenetic personalization of ADE therapy according to their ACS10 scores. Additionally, these results motivate research regarding the utility of ACS10 for pharmacogenetic personalization of other therapies for pediatric AML. Clofarabine is another nucleoside analog that inhibits both DNA polymerase as well as ribonucleotide reductase, thus enhancing the activity of ara-C. Recent data from the AML08 clinical trial [NCT00703820] has shown promising results with use of clofarabine with cytarabine during remission induction in pediatric AML patients.2 Therefore, we evaluated the association of ACS10 score with outcomes among 91 patients randomly assigned standard ADE induction on the AML02 clinical trial (LDAC arm) [NCT00136084] and 117 patients randomly assigned an induction of clofarabine and ara-C (Clo+Ara-C arm) on the AML08 trial [NCT00703820] (Figure 1A shows the study design). 5-year event-free survival (EFS) and overall survival (OS) of patients treated with ADE improved with increasing ACS10 score; however, for patients treated with Clo+Ara-C, improvement with increasing ACS10 score was not observed (OS shown in Figure 1A). This differential outcome association pattern suggests that thresholding the ACS10 score at 0 could be used to classify patients into low (<=0) and high (>0) ACS10 groups. Patients within low ACS10 score group had a better outcome with Clo+AraC whereas the high ACS10 score patient group fared better with ADE. In particular, there is significant improvement in EFS and OS within the low-ACS10 score patients when treated with Clo+Ara-C as compared to ADE (Clo+AraC vs. ADE; EFS HR=0.45, 95% CI: 0.23-0.82; p=0.01; OS HR=0.45, 95% CI: 0.19-0.93, p=0.028; Figure 1B). In contrast, patients with a high ACS10 score had worse EFS and OS with Clo+AraC induction than with ADE induction (EFS HR= 1.84, 95% CI: 0.99-3.41, p=0.05; OS HR= 2.40, 95%CI: 1.13-5.13; p=0.02, Figure 1B). These results are unlikely to suffer from a strong historical comparison bias because there are not statistically significant differences in the outcomes of the randomly assigned therapies of the AML02 and AML08 trials as well as outcome by the clinical trial (EFS/OS of each arm of the two trials as well as between AML02 and AML08 trials; p=0.8, data not shown). In summary, consistent with our recent report, these results show that for patients with Low-ACS10 genetic score prognosis is poor with standard ADE induction. However, therapy augmentation options such as Clo+AraC, ADE with high-dose Ara-C, and ADE+gemtuzumab may improve the prognosis. This calls for an action on using preemptive genotyping for selection of the most effective induction 1 chemotherapy regimen to achieve maximum clinical benefit. References. 1. Elsayed AH, et al: Polygenic Ara-C Response Score Identifies Pediatric Patients With Acute Myeloid Leukemia in Need of Chemotherapy Augmentation. JCO 2022, PMID:34990262 2. Rubnitz JE, et al: Clofarabine Can Replace Anthracyclines and Etoposide in Remission Induction Therapy for Childhood Acute Myeloid Leukemia: The AML08 Multicenter, Randomized Phase III Trial. JCO 2019, PMID:3124652 Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

AML-432 Overall Survival (OS) by Mutant Allele (R140 or R172) in Patients With Late-Stage, Mutant- Relapsed/Refractory Acute Myeloid Leukemia (AML) Treated With Enasidenib or Conventional Care Regimens (CCR) in the Randomized, Open-Label, Phase 3 IDHENTIFY Trial

IDH2 mutations (mIDH2) occur in ~8%-19% of patients with AML, typically as R140Q (~75%) or R172K (~25%) point mutations, which have distinct functional effects and prognostic relevance. In the phase 3 IDHENTIFY trial, enasidenib did not significantly improve OS vs CCR in older patients with mIDH2 relapsed/refractory AML, but a trend for improved OS with enasidenib was detected in patients with IDH2-R172. Investigate molecular profiles and OS in mIDH2 variant subgroups (R140/R172). IDHENTIFY (NCT02577406) enrolled patients aged ≥60 years who had received 2-3 prior AML-directed therapies. Patients were randomized 1:1 to enasidenib 100-mg/day or CCR (azacitidine, intermediate- or low-dose Ara-C, or supportive care). Co-occurring mutations were identified by targeted NGS of BMMC DNA. Total 2-hydroxyglutarate was determined by LC/MS. Of 319 patients enrolled, 88 (28%; 43 enasidenib, 45 CCR) had mIDH2-R172 and 229 (72%; 115 enasidenib, 114 CCR) had mIDH2-R140. Median baseline 2-hydroxyglutarate level and IDH2 VAF were similar between arms and mIDH2 subgroups. Patients with mIDH2-R172 had fewer baseline mutations (median 4 [range 2-8]) than those with mIDH2-R140 (5 [1-11]) (P<0.0001). Common co-mutations were SRSF2 and RUNX1 in the R140 cohort (59% each) and DNMT3A in the R172 cohort (57%). Compared with R172, R140 was enriched with SRSF2, FLT3 (-ITD/-TKD), NPM1, RUNX1, and JAK2, whereas DNMT3A and TP53 were more common with R172. In Cox multivariate analysis including mIDH2 variant, DNMT3A status, and number of baseline mutations, mIDH2-R172 was significantly correlated with improved OS (P=0.04 vs R140) in the enasidenib arm, and number of baseline mutations was significantly (P<0.01) associated with OS in the CCR arm. Median OS in the R172 subgroup was 14.6 months with enasidenib vs 7.8 months with CCR (HR, 0.59 [95%CI 0.35-0.98]; P=0.039); 1-year survival rates were 62% and 30%. In the R140 subgroup, median OS was 5.7 months in both arms (0.93 [0.70-1.24]; P=0.61), and 1-year survival rates were 29% and 25% with enasidenib and CCR. Mutational burden and co-mutational profiles differed between patients with mIDH2-R140 and mIDH2-R172 relapsed/refractory AML. In the R172 subgroup, median OS and 1-year survival rate with enasidenib were approximately double those with CCR.

The prognostic benefit from intermediate-dose cytarabine as consolidation therapy varies by cytogenetic subtype in t(8;21) acute myeloid leukemia: a retrospective cohort study.

BackgroundPatients with different karyotypes had different prognosis in t(8;21) acute myeloid leukemia (AML). Cytarabine (Ara-C) plays an important role as consolidation therapy in t(8;21) AML. T(8;21) AML patients with different karyotypes responded differently to post-remission therapy with Ara-C. However, the optimum dose of Ara-C in patients with different karyotypes remains unclear.MethodsFrom January 2002 to September 2018, a total of 188 younger adult (14–60 years) patients with t(8;21) AML were enrolled in this retrospective study. Cytogenetic analysis and aberration descriptions followed the International System for Human Cytogenetic Nomenclature. All the patients achieved first complete remission (CR1) after induction chemotherapy. Patients received low-dose Ara-C [LDAC (<1 g/m2)], intermediate-dose Ara-C [IDAC (1–1.5 g/m2)], or high-dose Ara-c [HiDAC (2–3 g/m2)] regimens as consolidation therapy after CR1. All patients were followed for survival or relapse until death, or study completion. We analyzed the prognosis of LDAC, IDAC, and HiDAC regimens as consolidation therapy in patients with different karyotypes. The primary endpoint was overall survival (OS) and the secondary endpoint was relapse-free survival (RFS).ResultsThe results showed IDAC significantly improved OS compared with LDAC [hazard rate (HR) =0.55, P=0.0375] when the clinical factors were adjusted. However, no significant difference between HiDAC and IDAC was found. Subgroup analysis further showed that the OS advantage of IDAC was focused on patients with additional cytogenetic abnormalities, including loss of X chromosome (-X), del(9q), or complex karyotype (group B, HR =0.21, P=0.0125), but not on patients with t(8;21)-only or additional loss of Y chromosome (-Y) cytogenetics (group A, HR =0.77, P=0.4804) in multivariate analysis. Similarly, better OS was shown after IDAC than LDAC consolidation in patients in group B, whether they received allogeneic hematopoietic stem cell transplantation (allo-HSCT) or not, but not in group A.ConclusionsIDAC was suitable for patients with additional -X, del(9q), or complex karyotype, while LDAC might be sufficient for patients with t(8;21)-only or additional -Y cytogenetics. It suggested that t(8;21) AML patients with different karyotypes should use different consolidation regimens.

P771: PROGNOSTIC CHARACTERISTICS OF PATIENTS WITH MDS WITH ABERRATIONS OF CHROMOSOME 5. DATA FROM THE DÜSSELDORF MDS REGISTRY

Background: Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders with a wide spectrum of biological and clinical features. Up to 20% of MDS patients present with aberrations of chromosome 5, either as isolated del(5q) or combined with other aberrations. Patients with a medullary blast count < 5% and isolated del(5q), or with one additional aberration except anomalies of chromosome 7, are diagnosed as MDS del(5q), a defined entity according to the WHO 2016 classification. They have a favorable prognosis compared to other types of MDS, although profound anemia, chronic transfusion dependency and the risk of disease progression into AML present clinical challenges. Aims: We analyzed the prognostic impact of karyotype complexity in MDS del(5q). Methods: From the Düsseldorf MDS registry we retrieved 499 patients with MDS or CMML according to WHO 2016, who showed any kind of del(5q). Biological and clinical parameters such as karyotype, IPSS-R and type of treatment were evaluated. Survival and progression to AML was calculated using Kaplan-Meier-plots. Cox regression analysis was performed to identify disease-related prognostic factors. Patients were followed up until Dec 31th 2021. Results: 58% of the patients were female, median age was 67 years. Median medullary blast count was 4% (0-19%), and median survival in the entire group was 28 months. For assessing the natural course of disease, we screened for patients with non-intensive treatment only (best supportive care, lenalidomide, low-dose Ara-C, hydroxyurea). Separation by medullary blast count (< 5%, 5-9% or ≥ 10%) was associated with significantly different median survival times, ranging from 63 months in the first group to 3 months in patients with ≥ 10% medullary blasts (p < 0.001). Survival was also affected by the cytogenetic risk group according to IPSS-R. Patients in the low-risk group (median survival 72 months) differed significantly from patients in the very high risk group (median survival 5 months) (p < 0.001). A similar trend was observed according to karyotype complexity represented by number of aberrations apart from del(5q). Median survival of patients with an isolated del(5q) was 86 months, while patients with a complex karyotype (del(5q) and ≥3 additional aberrations) had a median survival of 5 months. Biological risk factors were assessed using Cox regression analyses. Considering overall survival as endpoint, medullary blast percentage, cytogenetic risk group, and complexity of the karyotype had a significant impact on survival (p < 0.001). In the entire patient cohort, as well as among patients receiving non-intensive treatment, the rate of AML progression was significantly influenced by karyotype complexity (p < 0.001). While the median time to AML progression in both isolated del(5q) and del(5q) combined with one aberration had not been reached at the end of the observation period, the median time to AML progression for patients with del(5q) as part of a complex karyotype was 31 months in the entire cohort and 14 months in the low-intensity treatment group. Image:Summary/Conclusion: Both the IPSS-R cytogenetic risk group and the complexity of the 5q- karyotype showed prognostic impact in patients with del(5q). This was true for overall survival as well as risk of AML progression. Regardless of therapy or medullary blast count in patients with del(5q), the risk of AML progression increased dramatically with increasing complexity of the 5q- karyotype.

Health-related quality of life (HRQoL) with enasidenib versus conventional care regimens in older patients with late-stage mutant-IDH2 relapsed or refractory acute myeloid leukemia (R/R AML).

7032 Background: Enasidenib (ENA) is an oral inhibitor of mutant-IDH2 (mIDH2) proteins. In the phase 3 IDHENTIFY trial, ENA improved event-free survival (EFS), overall response, and complete remission rate vs conventional care regimens (CCR) ( P &lt; 0.01 for all) in patients (pts) ≥ 60 years of age with m IDH2 R/R AML with 2 or 3 prior treatments (Tx) (DiNardo 2021). Pt-reported HRQoL was a secondary trial endpoint. Methods: IDHENTIFY is an open-label, randomized trial (NCT02577406). Pts were preselected to a CCR (SC azacitidine, intermediate- or low-dose Ara-C, or supportive care) and then randomized 1:1 to ENA 100 mg/d or CCR in 28-d cycles. Key HRQoL endpoints were mean changes from baseline (CFB) overall and by clinical response in the Global Health Status/QoL, Physical Functioning, Role Functioning, Fatigue, and Dyspnea domains of the EORTC QLQ-C30 questionnaire, and in EQ-5D-5L utility index (UI) and visual analogue scale scores. The QLQ-C30 and EQ-5D-5L were assessed on D1 of each Tx cycle (C) and at end of Tx. Minimally important differences (MIDs) in CFB scores within or between Tx arms were based on accepted thresholds. Sensitivity analysis using imputed data on CFB was conducted using pattern mixture modeling. Results: HRQoL-evaluable cohorts included 118/158 (74.7%) pts in the ENA arm and 80/161 (49.7%) in the CCR arm; 40 ENA pts and 81 CCR pts were not evaluable due to missing data at baseline (BL; 22 ENA and 51 CCR) and/or at ≥1 post-BL visit (26 ENA and 69 CCR). Pts ineligible for HRQoL analyses had lower response rates and worse EFS and overall survival than HRQoL-evaluable pts. Overall QLQ-C30 completion rates in the ENA and CCR arms were 79% and 65%, respectively ( P &lt; 0.001). While there was no meaningful improvement or worsening from BL (ie, exceeding MID) within either Tx arm in the key QLQ-C30 domains, scores worsened during initial Tx cycles and then improved with continued Tx. Mean EQ-5D-5L scores also worsened during early cycles in both Tx arms, with meaningful UI deterioration in the ENA arm from C2 through C7. However, between-group comparisons showed no consistent differences between ENA and CCR in mean CFB. Sensitivity analysis with imputation of missing CFB data showed worsened HRQoL compared with non-imputed data in the CCR arm but not with ENA. In the ENA arm, clinical responders reported relatively stable mean HRQoL scores over time, and non-responders showed no meaningful differences in CFB vs the CCR arm. Conclusions: HRQoL measures tended to worsen during early cycles in both Tx arms and gradually improved with continued Tx. Data should be interpreted with caution as only approximately one-half of pts in the CCR arm were HRQoL-evaluable. ENA improved clinical efficacy measures vs CCR without compromising HRQoL in older pts with R/R AML. Clinical trial information: NCT02577406.

Overall survival by IDH2 mutant allele (R140 or R172) in patients with late-stage mutant-IDH2 relapsed or refractory acute myeloid leukemia treated with enasidenib or conventional care regimens in the phase 3 IDHENTIFY trial.

7005 Background: IDH2 gene mutations (m IDH2) occur in up to ̃20% of patients (pts) with acute myeloid leukemia (AML), most commonly as R140Q (in ̃75% of cases) or R172K (̃25%) point mutations. The functional effects and prognostic relevance of m IDH2-R140 and m IDH2-R172 can vary (Papaemmanuil 2016). In the randomized, phase 3 IDHENTIFY trial, enasidenib (ENA), an oral mIDH2 inhibitor, did not significantly improve overall survival (OS) vs conventional care regimens (CCR) as salvage treatment (Tx) for older pts with m IDH2 relapsed/refractory (R/R) AML in ITT analysis, but a trend for improved OS with ENA was detected in pts with IDH2-R172 mutations. We further investigated OS and correlative biomarkers in IDHENTIFY pt subgroups defined by m IDH2 variant (R140/R172). Methods: This open-label trial (NCT02577406) enrolled pts ≥ 60 years of age who had received 2 or 3 prior AML Tx. Pts were preselected to a CCR (azacitidine, intermediate- or low-dose Ara-C, or supportive care), and were then randomized 1:1 to ENA 100 mg/d or CCR in 28d cycles. Co-occurring gene mutations were identified by targeted next-generation sequencing (37-gene panel) of bone marrow mononuclear cell (BMMC) DNA. Total 2-HG levels were determined by LC/MS. Results: Of 319 pts enrolled, 88 pts (28%; 43 ENA, 45 CCR) had m IDH2-R172 and 229 (72%; 115 ENA, 114 CCR) had m IDH2-R140. Median baseline (BL) 2-HG levels were similar between Tx arms and m IDH2 variant subgroups, as were IDH2 variant allele frequencies. Pts with m IDH2-R172 had fewer median BL co-mutations (4 [range 2–8]) than did pts with m IDH2-R140 (5 [1–11]) ( P &lt; 0.0001). The most frequently co-occurring mutations were SRSF2 and RUNX1 in the R140 cohort (59% each) and DNMT3A in the R172 cohort (57%). Compared with the R172 cohort, the R140 group was enriched with SRSF2, FLT3 (-ITD/-TKD), NPM1, RUNX1, and JAK2 mutations, whereas DNMT3A and TP53 mutations were more common in the R172 group. In Cox multivariate analysis including m IDH2 variant (R140/R172), DNMT3A mutation status, and number of gene mutations at BL, m IDH2-R172 was significantly ( P = 0.04) correlated with improved OS (vs. R140) in the ENA arm, whereas the number of BL gene mutations was significantly ( P &lt; 0.01) associated with OS in the CCR arm. Median OS in the R172 subgroup was 14.6 mo with ENA vs 7.8 mo with CCR (HR, 0.59 [95%CI 0.35-0.98]; P = 0.039) and 1-yr survival rates were 62% and 30%, respectively. In m IDH2-R140 pts, median OS was 5.7 mo in both Tx arms (0.93 [0.70-1.24]; P = 0.61), and 1-year survival rates were 29% and 25% with ENA and CCR, respectively. Conclusions: Mutational burden and co-mutational profiles differed between pts with m IDH2-R140 and m IDH2-R172 R/R AML. ENA improved survival outcomes for pts with IDH2-R172 mutations, with median OS and 1-year survival rate approximately double those in the CCR arm. Clinical trial information: NCT02577406.

Polygenic Ara-C Response Score Identifies Pediatric Patients With Acute Myeloid Leukemia in Need of Chemotherapy Augmentation.

To establish a patient-specific polygenic score derived from cytarabine (ara-C) pathway pharmacogenomic evaluation to personalize acute myeloid leukemia (AML) treatment. Single nucleotide polymorphisms (SNPs) in the ara-C-pathway genes were analyzed with outcome in patients from the multicenter-AML02 trial (N = 166). Multi-SNP predictor modeling was used to develop 10-SNP Ara-C_SNP score (ACS10) using top SNPs predictive of minimal residual disease and event-free survival (EFS) from the AML02-cohort and four SNPs previously associated with ara-C triphosphate levels in the AML97 trial. ACS10 was evaluated for association with outcomes in each clinical trial arms: the standard low-dose ara-C (LDAC, n = 91) and augmented high-dose ara-C (HDAC, n = 75) arms of AML02 and the standard Ara-C, daunorubicin and etoposide (ADE) (n = 465) and the augmented ADE + gemtuzumab ozogamicin (GO; n = 466) arms of AAML0531 trial. In the standard LDAC-arm of AML02 cohort, the low-ACS10 score group (≤ 0) had significantly worse EFS (ACS10 low v high hazard ratio [HR] = 2.81; 95% CI, 1.45 to 5.43; P = .002) and overall survival (OS; HR = 2.98; 95% CI, 1.32 to 6.75; P = .009) compared with the high-ACS10 group (score > 0). These results were validated in the standard-ADE arm of AAML0531, with poor outcome in the low-ASC10 group compared with the high-ACS10 group (EFS: HR = 1.35, 95% CI, 1.04 to 1.75, P = .026; OS: HR = 1.64, 95% CI, 1.2 to 2.22, P = .002). Within the augmented arms (AML02-HDAC and AAML0531-ADE + GO), EFS and OS did not differ between low- and high-ACS10 score groups. In both cohorts, patients with low-ACS10 consistently showed a 10-percentage point improvement in 5-year EFS with augmented therapy (AML02-HDAC or AAML0531-ADE + GO arms) than with standard therapy (AML02-LDAC or AAML0531-ADE arms). Patients with low-ACS10 score experienced significantly poor outcome when treated on standard regimen. Augmentation with either high-dose ara-C or GO addition improved outcome in low-ACS10 group. A polygenic ACS10 score can identify patients with unfavorable pharmacogenetic characteristics and offers a potential for an elective augmented therapy option.

A Randomised Evaluation of Low-Dose Ara-C Plus BCT-100 Versus Low Dose Ara-C in Older Patients with Acute Myeloid Leukaemia: Results from the LI-1 Trial

Background: Among patients with Acute Myeloid Leukaemia (AML) over the age of 60, a considerable number are not considered suitable for intensive remission-induction chemotherapy. Survival in these patients is poor, whether they are treated using hypomethylating agents or low-dose ara-C (LDAC). The possibility of combination therapy with additional agents represents an attractive option. Arginine metabolism plays a key role in AML pathogenesis (Mussai et al. Blood 2013); BCT-100 is a pegylated recombinant human arginase that leads to a rapid depletion in extracellular and intracellular arginine concentrations resulting in G0/G1 arrest, and subsequent death by necrosis. BCT-100 demonstrates significant activity as single-agent against AML cell lines, AML xenografts and primary AML blasts from newly diagnosed or relapsed patients (Mussai et al. Blood 2015). Importantly BCT-100 is synergistic in combination with cytarabine.Aims: To assess the efficacy of LDAC+BCT100 versus LDAC alone in patients aged 60+ unsuitable for intensive therapy, in a “pick a winner” design. This design allows several treatments to be assessed simultaneously in a randomised fashion, with the aim of doubling 2-year survival from 11% to 22% (HR 0.69), with interim assessments after 50 and 100 patients per arm are recruited.Methods: LDAC was given at 20mg BD SC on days 1-10 of each course. Patients randomised to the combination received LDAC as above with BCT-100 1600U/kg on Days 1, 8, 15 and 22 as a 1-hour intravenous infusion. Courses occurred at 4-6 week intervals. Toxicities were recorded using CTCAE version 3. Pharmacokinetic and biomarker samples were assessed in BCT-100 patients. Results here are based upon median follow-up of 3.8 months (range: 0.1 - 20.6 months)Results: Between September 2018 and December 2020, 83 patients were randomised. The trial was prematurely closed due to the COVID pandemic and did not reach the pre-planned first evaluation. Median age was 76.7 years (range 62-88). Overall, 65% were male; 70% de novo AML, 23% secondary AML, and 6% high risk MDS; 2% favourable, 59% intermediate, 23% adverse and 15% unknown/unreported cytogenetics. Median of 2 courses was delivered in either arm (mean 2 LDAC, 2 LDAC+BCT, range for both: 1-12). BCT-100 leads to a depletion of arginine from baseline in the majority of patients.Overall response (CR/CRi) was achieved in 12/81 patients (15%), (LDAC+BCT-100 15%, LDAC 15%, R 1.03 (0.30, 3.51),P=0.963). Thirty-day mortality was not significantly increased (18% vs 11%, HR 1.71 (0.50, 5.84), P=0.393; and 1-year survival showed no evidence of a difference (31% vs 30%, HR 1.28 (0.72, 2.25). Median overall survival time was 3.8 vs 6.4months; overall survival HR 1.11 (0.64, 1.90), P=0.715. The most common cause of death was resistant/recurrent disease: 12(46%) vs 16(59%). BCT-100 was not associated with any haematological toxicity; although rare grade 3/4 cardiac and hepatic events were reported, these were not significantly increased with BCT-100.Summary: The addition of BCT-100 to LDAC did not improve response rate or survival. BCT-100 was well tolerated with an acceptable toxicity profile. Further clinical evaluation of BCT-100 induced arginase depletion continues in a variety of malignancies.Acknowledgements: We are grateful to Blood Cancer UK for funding the trial and Bio-Cancer Treatment International for providing drug and additional support for this Investigator Initiated Study.Figure 1. OS All patients [Display omitted] DisclosuresKnapper: Jazz: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Astellas: Ended employment in the past 24 months, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau. McMullin: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: clinical trial support, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AOP Orphan: Research Funding, Speakers Bureau. Copland: Incyte: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Cyclacel Ltd: Research Funding; Astellas: Honoraria, Speakers Bureau; Jazz: Honoraria, Speakers Bureau. Russell: Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees; Jazz: Research Funding, Speakers Bureau.

A Prospective Phase 2 Study of Venetoclax and Low Dose Ara-C (VALDAC) to Target Rising Molecular Measurable Residual Disease and Early Relapse in Acute Myeloid Leukemia

A Prospective Phase 2 Study of Venetoclax and Low Dose Ara-C (VALDAC) to Target Rising Molecular Measurable Residual Disease and Early Relapse in Acute Myeloid Leukemia