Odenike, Olatoyosi

Introduction: TP53 mutations are found in 18% of adult patients (pts) with acute lymphoblastic leukemias (ALL), and portends poor prognosis (Saygin, Blood Cancer Discov 2024). TP53 mutations are often associated with low hypodiploidy and Li Fraumeni syndrome (germline) in children. However, we and others have shown that TP53-mutant (TP53-m) ALL arises from pre-existing TP53-m clonal hematopoiesis in adults as opposed to germline origin. The impact of co-occurring mutations, TP53 allelic frequency (AF) and different types of treatment on outcomes of TP53-m ALL are not fully characterized. We set out to investigate the clinical and molecular predictors of outcomes in adults with TP53-mutant ALL. Methods: We retrospectively studied 107 patients with TP53-m ALL treated at seven different academic centers in North America. Genetic profiling of pre-treatment bone marrow samples was performed with a comprehensive panel covering 147 myeloid and lymphoid genes. We also performed RNA-sequencing to identify fusions that define ALL subtypes. Single nucleotide polymorphism (SNP) array was used to define low hypodiploidy. Results: The median age at diagnosis was 59 years (range, 10-80), 42% were female, 70% White. 89% of pts had B-ALL while 11% had T-lineage ALL. 24% of pts were classified to have therapy-related ALL based on their history of exposure to genotoxic therapy for another cancer. 45% of pts had hypodiploid karyotype, 79% of whom were low-hypodiploid. 7% had hyperdiploid karyotype and 5% had BCR::ABL1. 11 pts had two different TP53 variants. 90% of TP53 variants involved the DNA binding domain. Most frequently observed co-occurring mutations involved CDKN2A (20%), NOTCH1 (12%) and RB1 (10%) genes. 71% of pts were treated with standard cytotoxic chemotherapy, while the remaining pts received newer antibody-based therapies (i.e., inotuzumab, blinatumomab) or venetoclax in first-line setting. 11% of pts received allogeneic hematopoietic cell transplant (HCT) in first complete remission (CR1) while 3% received HCT after relapse (CR2 or CR3). When patients with vs without low hypodiploidy were compared, we did not observe a significant difference in overall survival (OS) as outcomes were poor in both groups (median, 17 vs 19 months, p= 0.89). However, pts who had TP53 AF >0.5 had significantly worse OS when compared to pts with TP53 VAF <0.5 (13 vs 25 months, p= 0.03). Conclusions: TP53-m ALL is a very high-risk disease subtype and its dismal outcome is independent from presence of co-existing low hypodiploidy. Loss of heterozygosity, characterized by TP53 AF >0.5 is associated with even worse survival. New therapies are urgently needed to improve outcomes in this subset.

Background: Chromosomal rearrangements involving the KMT2A gene and mutations involving the nucleophosmin (NPM1) gene have been associated with response to menin inhibitors in multiple studies of acute myeloid leukemia (AML) patients characterized by these genetic alterations. Both alterations are more common in younger AML patients and those with NPM1 mutations historically perform better. However, the prevalence and outcomes of older (≥60 years) AML patients with these alterations who are treated with current therapies is less well understood. We present results from the Beat AML Master Trial (BAMT) that analyze the outcomes of this large, but less common subset of patients in an older AML population. Methods: Patients were consented and enrolled on this precision medicine-based Beat AML Master Trial (NCT03013998) from November 2016 to June 2024. Patients were included in this analysis if they harbor either the classic NPM1 mutation or a KMT2A rearrangement (over 10 different gene partners). Additionally, 2 patients with a NUP98 rearrangement were included with the KMT2A cohort as they are known to have similar biology in terms of menin dependence. These patients were treated with the following therapies: a sub-study specific targeted therapy for the dominant clone, venetoclax + hypomethylating agent (Ven/HMA), intensive chemotherapy (IC), alternative non-intensive therapy (NIT), or no therapy. Clinical/genetic characteristics and median overall survival (OS) were analyzed in each group separately. Overall survival (OS) was calculated from master consent and estimated using the Kaplan-Meier method. Results: Of 1096 AML patients enrolled on the BAMT, 246 patients had either an NPM1 (N=207, 18.9%) or KMT2A (N=39, 3.6%) genetic alteration. The baseline characteristics for the NPM1 cohort were median age 72 years (range: 60-92), 50% female, and ECOG performance status: 0-16%, 1-58%, 2-25% and 3-1%. Additional disease characteristics include treatment related AML at 11% and complex karyotype (≥3 abnormalities) at 3%. Median OS for the entire NPM1 cohort was 18.4 months (95% CI: 14.2-24.7). Patients were treated on a sub-study (35%), Ven/HMA (19%), IC (26%), NIT (8%) or no treatment (9%). Between treatment groups, median OS was 21 months (95% CI: 12.8-31.7) for those treated on a sub-study, 22 months (95% CI: 12.6-not reached (NR)) for Ven/HMA, 41.6 months (95% CI: 18.2-NR) for IC, and 6.3 months (95% CI: 1.3-23) for NIT, which was significantly different (p<0.0001). The baseline characteristics for the KMT2A cohort were median age 69 years (range: 60-88), 44% female, and ECOG performance status: 0-19%, 1-45%, 2-35% and 3-0%. Treatment related AML occurred in 23% of patients and complex karyotype in 31%. Median OS for the KMT2A cohort was 6.5 months (95% CI: 3.6-31.6). Patients were treated on a sub-study (38%), Ven/HMA (15%), IC (15%), NIT (15%), or no treatment (5%). Between treatment groups, median OS was 31.6 months (95% CI: 3.2-NR) for sub-study, 5.0 months (95% CI: 3.0-NR) for Ven/HMA, 12.7 months (95% CI: 4.9-NR) for IC, and 2.9 months (95% CI: 1.5-NR) for NIT, which was also significantly different (p<0.0001). Conclusions: In this cohort of older AML patients who possess NPM1 or KMT2A mutations, initial demographics and clinical characteristics upon presentation are as expected. Within each cohort and depending on the type of therapy received, there were interesting differences in survival. Median OS was the highest for the NPM1 cohort that received IC while the KMT2A cohort had the highest median OS when enrolled on a KMT2A targeted sub-study; a finding that supports precision-based medicine for this high-risk KMT2A group characterized by poor outcomes. As menin inhibitor combinations with induction chemotherapy or Ven/HMA move to the frontline setting, we anticipate seeing significant improvement in outcomes for AML patients in both of these genomic subsets. Further multivariable analysis will be performed to validate treatment effect on OS. Our analyses for these two cohorts also provide valuable outcome benchmarks for the design of future precision oncology studies that seek to improve survival in these subsets of older AML patients.

Introduction: The development of increasingly sensitive tests for the detection of measurable residual disease (MRD), such as multiparameter flow cytometry (MFC) and next-generation sequencing (NGS) assays, has changed clinical practice in acute lymphoblastic leukemia (ALL). IGH V(D)J-based NGS MRD is the most sensitive assay to predict relapse in patients (pts) with B-ALL (Short, Blood Adv 2022). However, data regarding the use of T-cell receptor (TR) NGS MRD in T-ALL are limited and recent reports from pediatric cohorts suggest that persistent TR MRD may not predict relapse in T-ALL (Roy, ASH 2023, abstract 2976). With limited options for the treatment of relapsed/refractory T-ALL, accurate prediction of high relapse risk may provide an opportunity for early intervention. In this study, we evaluated the prognostic utility of TRB/TRG NGS MRD and its correlation with MFC MRD in adult patients with T-ALL. Methods: We retrospectively evaluated the MRD data and clinical outcomes of precursor T (pre-T) and early T precursor (ETP) ALL patients treated at four academic centers in the US. MRD was evaluated using MFC in CLIA-certified labs at individual sites with a sensitivity of 10-4, and the clonoSEQ (Adaptive Technologies, lnc) NGS assay, with a sensitivity of 10-6. Pts were included if they had a trackable TR clone and NGS MRD remission assessment in at least one time point. The correlation between the percentage of MRD by MFC vs NGS was calculated with the Pearson correlation coefficient, using every available MRD assessment for T-ALL pts in complete remission. Relapse-free survival was stratified based on NGS MRD level at the time of post-induction and post-consolidation assays, and comparisons were made with the log-rank test. The positive predictive value (PPV) for relapse of NGS MRD was calculated for pts with MRD > 10-6 at the post-induction and post-consolidation period. Results: A total of 19 pts who met our inclusion criteria, with a median age of 30 years (range, 18-65). 9 pts (47%) had ETP-ALL, 10 pts had pre-T ALL. Pts had a trackable TRB/TRG clone in 76% of cases, with 66% having a trackable TRG clone and 38% having a trackable TRB clone. 10 pts (53%) were treated with a modified AALL0434 regimen as first line therapy, 6 pts (32%) were treated with CALGB10403, 1 pt (5%) was treated with hyperCVAD, 1 pt (5%) was treated with a BFM regimen, and 1 pt (5%) was treated with CALGB9511. Out of 11 T-ALL pts with MRD data available post-induction, 6 pts (55%) had detectable MRD by NGS and no detectable MRD by MFC. Out of 13 pts with available post-consolidation MRD data, 2 pts (15%) had undetectable MRD by both NGS and MFC and 9 pts (69%) had detectable MRD by NGS only. There were no pts with detectable MRD by MFC and undetectable MRD by NGS at either timepoint. A total of 64 MRD data points from 19 pts were available to evaluate MRD correlation by MFC vs NGS, for which the Pearson correlation coefficient showed a statistically significant linear correlation (p < 0.01). At post-induction, 9 pts had NGS MRD > 10-4 and 2 pts had NGS MRD < 10-4. With a median follow-up time of 19.8 months, pts with NGS MRD > 10-4 had a median RFS of 19.8 months and pts with NGS MRD < 10-4 had a median RFS of 14.8 months. The log-rank test comparing RFS between these two groups was not statistically significant (p= 0.18). Persistent NGS MRD at post-induction had a PPV for relapse of only 18%. At post-consolidation, 7 pts had NGS MRD > 10-4, 4 pts had NGS MRD < 10-4, and 2 pts had undetectable MRD by NGS. With a median follow-up time of 17.3 months, pts with NGS MRD > 10-4 had a median RFS of 15.3 months and pts with NGS MRD < 10-4 or undetectable had a median RFS of 20.6 months. The log-rank test comparing RFS between these two groups was not statistically significant (p= 0.6). Persistent NGS MRD at post-consolidation had a PPV for relapse of only 27%. Conclusion: Despite statistically significant linear correlation between MFC and NGS MRD testing, there were no RFS differences between pts with NGS MRD > 10-4 vs NGS MRD < 10-4. All patients had persistent NGS MRD post-induction, which is markedly lower than the reported 20-25% NGS undetectable MRD rate in B-ALL post-induction. Persistent NGS MRD has low PPV for relapse in T-ALL, which limits its utility in clinical decision making for this population.

Abstract With emerging new drugs in myelofibrosis (MF), a robust and harmonized framework for defining the severity of anemia and response to treatment will enhance clinical investigation and facilitate interstudy comparisons. Accordingly, the lead authors on the 2013 edition of the International Working Group–European LeukemiaNet (IWG-ELN) response criteria in MF were summoned to revise their document with the intent to (1) account for gender-specific differences in determining hemoglobin levels for eligibility criteria; (2) revise the definition of transfusion-dependent anemia (TDA) based on current restrictive transfusion practices; and (3) provide a structurally simple and easy to apply response criteria that are sensitive enough to detect efficacy signals (minor response) and also account for major responses. The initial draft of the 2024 IWG-ELN proposed criteria was subsequently circulated around a wider group of international experts and their feedback incorporated. The proposed articles include new definitions for TDA (≥3 units in the 12 weeks before study enrollment) and hemoglobin thresholds for eligibility criteria (<10 g/dL for women and <11 g/dL for men). The revised document also provides separate (TDA vs non-TDA) and graded (major vs minor response) response criteria while preserving the requirement for a 12-week period of screening and observation on treatment.

Abstract Although the 2022 European LeukemiaNet (ELN) acute myeloid leukemia (AML) risk classification reliably predicts outcomes in younger patients treated with intensive chemotherapy, it is unclear whether it applies to adults ≥60 years treated with lower-intensity treatment (LIT). We aimed to test the prognostic impact of ELN risk in patients with newly diagnosed (ND) AML aged ≥60 years given LIT and to further refine risk stratification for these patients. A total of 595 patients were included: 11% had favorable-, 11% intermediate-, and 78% had adverse-risk AML. ELN risk was prognostic for overall survival (OS) (P < .001) but did not stratify favorable- from intermediate-risk (P = .71). Within adverse-risk AML, the impact of additional molecular abnormalities was further evaluated. Multivariable analysis was performed on a training set (n = 316) and identified IDH2 mutation as an independent favorable prognostic factor, and KRAS, MLL2, and TP53 mutations as unfavorable (P < .05). A “mutation score” was calculated for each combination of these mutations, assigning adverse-risk patients to 2 risk groups: −1 to 0 points (“Beat-AML intermediate”) vs 1+ points (“Beat-AML adverse”). In the final refined risk classification, ELN favorable- and intermediate-risk were combined into a newly defined “Beat-AML favorable-risk” group, in addition to mutation scoring within the ELN adverse-risk group. This approach redefines risk for older patients with ND AML and proposes refined Beat-AML risk groups with improved discrimination for OS (2-year OS, 48% vs 33% vs 11%, respectively; P < .001), providing patients and providers additional information for treatment decision-making.

Background: Acute myeloid leukemia (AML) therapy in older patients (age ≥ 60) has undergone a transformation with the introduction of multiple targeted therapies, which has allowed more patients to receive therapy than before. The most successful has been the combination of venetoclax + azacitidine (VA) which generated higher overall complete response rates in phase 2 studies than would be expected with azacitidine alone, leading to accelerated FDA approval on 21Nov2018. The VIALE-A phase 3 study confirmed the improved overall survival (OS, median 14.7 versus 9.6 months) of VA, leading to full FDA approval for marketing. This retrospective analysis provides real world data on the impact of baseline clinical and genomic markers of individuals receiving intensive chemotherapy versus VA. Methods: The precision medicine Beat AML Master Trial (NCT03013998) assigns patients to biomarker specific sub-study treatments based on targeted DNA sequencing and cytogenetics. However, a large subset of patients did not enroll on a sub-study, but were followed for off-study treatment and OS. From this subset, patients enrolled onward from 21Nov2018, when VA received accelerated approval, were examined for differences in clinical/genetic characteristics and OS in those receiving venetoclax + hypomethylating agent (V/HMA), any form of intensive chemotherapy (IC), alternative non-intensive therapy (NIT), or no therapy. The genetic mutations identified in this study are characterized by a variant allele frequency of 20%+, as defined in the trial for determining the dominant clone. The method of Kaplan-Meier was used to estimate OS, and the Cox model was fit to associate patient characteristics with OS. Results: From 21Nov2018, a total of 468 AML patients consented to the Beat AML trial and did not enroll to a sub-study. Treatment was chosen by the investigator based upon available clinical and genomic data. Of these 468 patients, 62 did not receive treatment, 2 had treatment data missing, 226 were treated with V/HMA, 112 with IC, and 66 with NIT. Demographics for all patients include median age 71 (60-90), 40% female, performance status (PS) (0-20%; 1-55%; 2-22%; 3-3%), median white blood cell (WBC) 4.1 (range 0.3-298.6), complex karyotype (CK) 20.6%, core binding factor (CBF) 7.8%, KMT2A-rearranged 3.6%, NPM1-mutated (m) 15.6%, IDH2m 14.6%, TP53m 13.2%, FLT3-ITD/TKD 12.9%, and NRASm/ PTPN11m/ KRASm/ NF1m/ CBLm 23.6%. Demographics that were significantly different (p<0.01) among the three groups (V/HMA, IC, and NIT) include age (younger in IC), PS (worse in NIT), AST/ALT (worse in NIT), CBF (more in IC), CK and TP53m (less in IC). Of the 404 patients who underwent treatment with V/HMA, IC, or NIT, 208 have died with those surviving having a median follow-up of 22.3 months. Figure 1 summarizes the OS of each treatment group. The median OS (95% CI) from time of initiating therapy is 13.6 (10.9-16.8) for V/HMA, 33.8 (20.7-not reached) for IC, and 11.6 (5.2-21.3) months for NIT. Univariable analysis for OS was significant at p<0.05 for increased age, WBC, PS, hemoglobin, CBF, CK, NPM1m, TP53m, TET2m and IC versus V/HMA. Multivariable analysis was significant at p<0.05 (hazard ratio) for increased age (1.14), PS (1.83), WBC (1.08), hemoglobin (0.91), and select genomic aberrations including CBF (0.37), NPM1m (0.35), and TP53m (2.1). Conclusions: These results from a large cohort of older AML patients treated with V/HMA, IC, or NIT show that their outcome is best defined by pre-treatment clinical features previously identified including age, performance status, WBC and hemoglobin along with limited genomic characteristics including CBF, NPM1m, and TP53m. While univariate analysis of OS favored IC over V/HMA and NIT, multivariable analysis supports that this advantage was most likely due to the favorable clinical and genomic features. The OS of V/HMA patients in this cohort is similar to that in the VIALE-A registration study of VA, providing further justification for this treatment for older AML patients deemed ineligible for intensive chemotherapy. Additionally, this data supports use of the patient cohort in this study for ongoing work in understanding and/or validating biomarkers associated with survival with V/HMA.

Background. Acute myeloid leukemia (AML) is a heterogenous disease that occurs primarily in older adults with a median age of 69 years at diagnosis. Most studies that characterize the genomic landscape of AML include younger adults with the majority of patients being younger than 60 years of age. We aimed to study the mutational landscape of newly diagnosed AML patients aged 60 years or older. Methods.Samples were collected from the multi-center Beat AML Master Trial (Burd, Nat Med 2020). Patients were enrolled between 2016 and 2023. Informed consent was obtained according to the Declaration of Helsinki. Patients diagnosed with non-APL AML and who were aged ≥ 60 years old were included. Patients underwent bone marrow aspiration and biopsy, cytogenetic analysis, FLT3-ITD ratio assessment (LeukoStrat CDx FLT3 Mutation Assay, Invivoscribe) and next generation sequencing (NGS) using FoundationOne®Heme(Foundation Medicine) to interrogate the entire coding region of 406 genes and select introns of 31 genes involved in rearrangements, as well as RNA sequencing to interrogate 265 genes known to be somatically altered in human hematological malignancies. The presence of multiple hotspot mutations within one gene in an individual patient was counted as one gene mutation. Patterns of co-occurrence between gene mutations were calculated using the Phi correlation coefficient. Statistical analyses were performed using R statistical software. P<0.01 was considered statistically significant. Results. A total of 1088 newly diagnosed AML patients were identified, of whom 1032 were 60 years or older. Patients had a median age of 72 years at time of diagnosis (range 60-92 years). Forty-two percent of the patients were female, most patients were non-Hispanic and 79% were Caucasian. NGS data were available for 1024 patients and mutations were identified in 461 different genes. Patients had a median number of 11.0 mutations (range 3.0 to 28.0). The most frequently mutated genes were DNMT3A (n=257; 25.1%), TP53(n=255; 24.9%), TET2 (n=243; 23.7%), RUNX1 (n=225; 22.0%), SRSF2 (n=221; 21.6%), ASXL1 (n=216; 21.1%), NPM1 (n=206; 20.1%), FLT3 (n=205; 20.0%), IDH2 (n=190; 18.6%), NRAS (n=208; 16.9%), PTPN11(n=104; 10.2%), STAG2 (n=101, 9.9% and IDH1 (n=99; 9.7%) (Figure 1A). FLT3-ITD was present in 98 (12.1%) of the 810 patients who were tested. Strongest significant co-occurrence was found between FLT3and NPM1 (n=103), STAG2 and ASXL1 (n=63), ASXL1 and RUNX1 (n=92), ASXL1 and SRSF2 (n=88), RUNX1 and SRSF2 (n=94), STAG2 and SRSF2 (n=51) and DNMT3A and NPM1 (n=92) (p<0.01). Pairwise negative correlations were observed between TP53 and NPM1 (n=6), TP53 and SRSF2 (n=17), and between NPM1 and RUNX1 (n=6) (p<0.01) (Figure 1B). The cytogenetic profiles and the full genomic landscape will be presented during the ASH meeting. Discussion. This is the largest study investigating the mutational profile in older adults with AML aged 60 years and older. Due to the 7-day screening period of the Beat AML study, patient selection was biased towards less-rapidly proliferative AML. We showed that the pattern of gene mutations was markedly different from other studies in AML that mainly included younger AML patients (Papaemmanuil, NEJM 2016; TCGA, NEJM 2013 ). The frequency of mutated TP53 was substantially higher in older AML patients, as was the occurrence of myelodysplasia-related gene mutations (e.g., SRSF2, RUNX1, ASXL1, STAG2, U2AF1, and SF3B1) and gene mutations in IDH1, IDH2 and TET2. In contrast, NPM1 mutation was less frequently mutated in older AML patients. Furthermore, we demonstrated that a large proportion (46%) of the AML patients older than 60 years of age do have a mutation that is potentially targetable for treatment ( FLT3 IDH1 IDH2 and NPM1). The high incidence of mutated TP53 and MDS-related gene mutations underscores the increased incidence of high-risk AML and the need for innovative personalized therapies in this older age group. Figure 1. A. Co-occurrence of the 15 most frequently mutated genes, and B. co-correlation between the 15 most frequently mutated genes. Blue indicates positive correlation, red indicated negative correlation. Only significant correlations (p<0.01) are shown.

Background. The inclusion of gene mutations and chromosomal abnormalities in the 2022 WHO and ICC Classifications of MDS has enhanced diagnostic precision and is expected to improve clinical decision-making process. Although these two systems share similarities, clinically relevant discrepancies still exist and potentially cause inconsistency in their adoption in a clinical setting. In this study on behalf of the International Consortium for MDS (icMDS), we adopted a data-driven approach to provide a harmonization roadmap between the 2022 WHO and ICC classification for MDS. A modified Delphi Process consensus approach is currently ongoing among icMDS experts to finalize a harmonized MDS classification scheme. Methods. We analyzed retrospective international cohorts of patients with a diagnosis of MDS (n=7017) and AML (n=1002) according to WHO 2016 criteria. Hierarchical Dirichlet Processes were applied to define clusters capturing broad dependencies among all gene mutations and cytogenetic abnormalities. To investigate the features of importance and their impact on the clustering process, we employed the SHapley Additive exPlanations approach (SHAP). This allowed to define harmonized labels for each clinical entity. The clinical relevance of the unsupervised clustering was assessed through the analysis of phenotypic features and outcomes among each group. ( Blood 2022;140: 9828-9830) Results. Patients' characteristics are summarized in Table 1. We identified 9 clusters, defined by specific genomic features. The cluster of highest hierarchical importance was characterized by biallelic inactivation of TP53 (biTP53). According to SHAP analysis, bi TP53 was defined as 2 or more TP53 mutations, or 1 mutation with copy number loss or cnLOH. Most patients assigned to bi TP53 cluster had TP53 VAF>10% (77.9%) and complex karyotype (70.1%). Assignment to bi TP53 cluster was irrespective of blast count. Patients with monoallelic TP53 mutation segregated into other clusters. Hierarchically, the second cluster included patients with del(5q). SHAP analysis highlighted 5q deletion alone, or with one other chromosomal abnormality other than -7, and absence of bi TP53, as the most relevant features. Most of these patients had blast counts <5% (88.1%). The third distinct cluster included patients with SF3B1 mutations (in the absence of concurrent del(7q), abn3q26.2, complex karyotype or RUNX1 mutation). Most patients with MDS and SF3B1 mutation had <5% blasts (94.2%). Common co-mutated variants in the SF3B1 cluster included mutant DNMT3A (25.2%) and TET2 (38.3%). Morphologically defined MDS cases (i.e., not meeting criteria for bi TP53, del(5q) or SF3B1) were preferentially assigned to the following additional clusters: SF3B1 and concurrent higher-risk mutations (e.g., RUNX1 and ASXL1); SRSF2 and concomitant TET2 mutations; U2AF1 mutations with del(20q), del(7q) or -7; SRSF2 with TET2 mutations and co-mutational patterns including RUNX1 and ASXL1; and AML-like genomic signatures. Our analyses suggest that morphologically defined MDS is characterized by a large heterogeneity in terms of mutation profiles, not entirely captured by the presence of unilineage versus multilineage dysplasia, percentage of bone marrow blasts, and presence of hypocellularity and fibrosis. To better investigate the continuum between high risk MDS (i.e., patients with ≥10% blasts) and AML, an exploratory comparison was made using a cohort of AML (defined according to WHO 2016) patients analyzed using the same statistical methods. Only a partial overlap in genetic signatures was observed between MDS with ≥10% blasts and AML. However, similarities were observed between the AML-like MDS clusters (characterized by mutant NPM1, bZIP CEBPA, and Core Binding Factor abnormalities) and AML clusters defined by the same genetic signature, thus supporting the classification of these entities as AML, irrespective of blast count. Conclusion. Our study demonstrated the utility of a data-driven approach based on advanced statistical methods to generate a harmonized classification for MDS. Table 2 shows a provisional, hierarchical classification algorithm. Further refinement of entity labels and classification criteria is the subject of the ongoing modified Delphi Process consensus approach among icMDS experts.

Background: Oral decitabine/cedazuridine (ASTX727) is a fixed dose combination of decitabine (35 mg) and the cytidine deaminase inhibitor cedazuridine (100 mg) given once daily X 5 days on a 28-day cycle producing pharmacokinetic (PK) exposure equivalent to the standard intravenous (IV) decitabine regimen of 20 mg/m 2 daily X 5 days on a 28-day cycle. This was demonstrated in the pivotal ASCERTAIN study (Garcia-Manero, et al, ASH 2019) as it provided a PK bridge to existing decitabine data and demonstrated median OS was 31.7 mo. (Savona,et al. Intl. MDSF International Congress on MDS, 2021). Subjects were initially classified by the International Prognosis Scoring System (IPSS) for historical reasons, however IPSS-R and IPSS-M are enhancements to IPSS that provide dynamic risk assessment for predicting clinical outcomes in MDS. Here, the objective was to re-classify the MDS subjects enrolled on the ASCERTAIN study by IPSS-R and IPSS-M and measure the impact of informing patient outcomes based on re-calculated risk assessment. Methods: One hundred thirty-three subjects with MDS/CMML (chronic myelomonocytic leukemia) were enrolled in ASCERTAIN and were randomly assigned either IV decitabine for cycle 1 and oral decitabine/cedazuridine for cycle 2 or the opposite treatment sequence. All subjects continuing beyond cycle 2 received oral decitabine/cedazuridine for all subsequent cycles until treatment discontinuation for disease progression, toxicity, patient's decision, or HSCT. Whole blood collected prior to treatment was used for DNA isolation and molecular abnormalities identified using next-generation sequencing (NGS) hematologic malignancy panel of 179 genes including all genes commonly mutated in MDS. In the initial analysis of clinical outcomes, subjects were classified by IPSS with response assessment by IWG 2006 IPSS low and Int-1 risk levels were categorized as lower-risk MDS (LR-MDS), whereas IPSS Int-2 and high-risk categories were categorized as higher-risk MDS (HR-MDS). Subjects with sufficient data based on (e.g., available heme parameters, cytogenetics, NGS etc.) were reclassified by IPSS-R and IPSS-M. Subjects with IPSS-R score of ≤3.5 or IPSS-M of either very low, low, or moderate low were categorized as LR-MDS. Similarly subjects with IPSS-R score of >3.5 or an IPSS-M categorization of either moderate high, high, or very high were categorized as HR-MDS. Reclassified subjects were reassessed for CR (Complete Response), OS, and LFS and Harrell's concordance index (c-index) was used to describe the level of agreement between each scale and outcomes. Results: Based on the available data, the number of MDS subjects in the different risk classifications were the following: IPSS: 117, IPSS-R: 104, and IPSS-M: 105. Thirteen and 12 subjects on the IPSS could not be reclassified in the IPSS-R and IPSS-M, respectively, including 5 Int-1 and 2 low-risk MDS cases. CMML subjects were excluded from these analyses. Re-classification generally resulted in the upgrade of the subjects from LR-MDS to HR-MDS (Fig. 1). Thirty-one (26.5%) subjects from IPSS were reallocated in the IPSS-R to different risk categories; 3 (9.7%) were downgraded and 28 (90.3%) were upgraded. Similarly on reclassification with IPSS-M 34 (32.4%) of the patients reclassified; 5 (14.8%) were downgraded and 29 (85.3%) were upgraded. For IPSS LR-MDS, 23.2% of patients achieved CR, and 22.9% in the IPSS HR-MDS. Similarly, 21.6% patients achieved CR in the IPSS-R LR-MDS, and 23.9% in the IPSS-R HR-MDS; 26.3% patients achieved CR in the IPSS-M LR-MDS, and 20.9% in the IPSS-M HR-MDS. The c-index for the IPSS was .64 (OS) and .67 (LFS), IPSS-R was .70 (OS) and .71 (LFS), and .75 (OS) and .78 (LFS) for the IPSS-M (Table1). Conclusion: Reclassification from IPSS to IPSS-R or IPSS-M upgraded multiple subjects from a LR to a HR category, describing the ASCERTAIN patient population as a majority higher risk population with worse prognosis than previously assumed based on the IPSS. The efficacy as measured by the CR rates did not change when the LR and HR categories were defined by the different risk stratification systems. In contrast, the c-index improves with migration from IPSS to IPSS-R to IPSS-M, indicating an increased discriminatory ability of IPSS-M score in comparison to IPSS and IPSS-R, to predict patient outcomes.

Abstract Acute myeloid leukemia (AML), an aggressive malignancy with unmet medical need, lacks immunotherapeutic options. CD123, the cellular receptor for interleukin-3, expressed in AML is an attractive target for tumor-specific therapy. Vibecotamab (XmAb14045), a humanized bispecific antibody, monovalently binds both CD3 and CD123 to recruit cytotoxic T cells to kill CD123+ tumor cells. This phase 1 study’s primary objectives were safety and tolerability and identification of a maximum tolerated dose/recommended dose for use as monotherapy in patients with relapsed/refractory AML. Identification of a recommended phase 2 vibecotamab dose comprised 3 step-up doses (Week 1), which were noted to reduce cytokine response syndrome (CRS), followed by weekly dosing (1.7 μg/kg, Cohort -1D). In 16 of 120 patients, at least 1 treatment-emergent adverse event was classified as a dose-limiting toxicity. CRS, the most common adverse event (59.2%), managed with premedication, were mostly ≤grade 2. A secondary objective was assessment of efficacy in patients with CD123-expressing leukemias. A total of 10 of 111 (9.0%) efficacy-evaluable patients with AML achieved an overall response of morphologic leukemia-free state or better with an overall objective response rate (ORR) of 9.0%. Response was only observed in patients receiving a target dose of 0.75 μg/kg or higher (n = 87) in which the efficacy-evaluable ORR was 11.5%. Response was associated with lower baseline blast counts in blood and bone marrow (<25%) suggesting potential benefit. This trial was registered at www.clinicaltrials.gov as #NCT02730312.