ELN Classification Research Articles

Imatinib with intensive chemotherapy in AML with t(9;22)(q34.1;q11.2)/BCR::ABL1. A DATAML registry study

Acute myeloid leukemia (AML) with t(9;22) (q34.1; q11.2)/BCR::ABL1, a distinct entity within the group of AML with defining genetic abnormalities, belong to the adverse-risk group of the 2022 ELN classification. However, there is little data on outcome since the era of tyrosine kinase inhibitors. Among 5819 AML cases included in the DATAML registry, 20 patients with de novo BCR::ABL1+AML (0.3%) were identified. Eighteen patients treated with standard induction chemotherapy were analyzed in this study. Imatinib was added to chemotherapy in 16 patients. The female-to-male ratio was 1.25 and median age was 54 years. The t(9;22) translocation was the sole chromosomal abnormality in 12 patients. Main gene mutations detected by NGS were ASXL1, RUNX1 and NPM1. Compared with patients with myeloid blast phase of chronic myeloid leukemia (CML-BP), de novo BCR::ABL1+AML had higher WBC, fewer additional chromosomal abnormalities, lower CD36 or CD7 expression and no ABL1 mutations. Seventeen patients (94.4%) achieved complete remission (CR) or CR with incomplete hematologic recovery. Twelve patients were allografted in first remission. With a median follow-up of 6.3 years, the median OS was not reached and 2-year OS was 77% (95% CI: 50–91). Four out of five patients who were not transplanted did not relapse. Comparison of BCR::ABL1+AML, CML-BP, 2017 ELN intermediate (n = 643) and adverse-risk patients (n = 863) showed that patients with BCR::ABL1+AML had a significant better outcome than intermediate and adverse-risk patients. BCR::ABL1+AML patients treated with imatinib and intensive chemotherapy should not be included in the adverse-risk group of current AML classifications.

Stellae-123 gene expression signature improved risk stratification in Taiwanese acute myeloid leukemia patients

The European Leukemia Net recommendations provide valuable guidance in treatment decisions of patients with acute myeloid leukemia (AML). However, the genetic complexity and heterogeneity of AML are not fully covered, notwithstanding that gene expression analysis is crucial in the risk stratification of AML. The Stellae-123 score, an AI-based model that captures gene expression patterns, has demonstrated robust survival predictions in AML patients across four western-population cohorts. This study aims to evaluate the applicability of Stellae-123 in a Taiwanese cohort. The Stellae-123 model was applied to 304 de novo AML patients diagnosed and treated at the National Taiwan University Hospital. We find that the pretrained (BeatAML-based) model achieved c-indexes of 0.631 and 0.632 for the prediction of overall survival (OS) and relapse-free survival (RFS), respectively. Model retraining within our cohort further improve the cross-validated c-indexes to 0.667 and 0.667 for OS and RFS prediction, respectively. Multivariable analysis identify both pretrained and retrained models as independent prognostic biomarkers. We further show that incorporating age, Stellae-123, and ELN classification remarkably improves risk stratification, revealing c-indices of 0.73 and 0.728 for OS and RFS, respectively. In summary, the Stellae-123 gene expression signature is a valuable prognostic tool for AML patients and model retraining can improve the accuracy and applicability of the model in different populations.

EPR24-100: A Comparison of Somatic Mutations and ELN Classification in De Novo Acute Myeloid Leukemia Between Appalachian and Non-Appalachian Kentucky.

EPR24-100: A Comparison of Somatic Mutations and ELN Classification in De Novo Acute Myeloid Leukemia Between Appalachian and Non-Appalachian Kentucky.

A blastic plasmacytoid dendritic cell neoplasm-like immunophenotype is negatively associated with CEBPA bZIP mutation and predicts unfavorable prognosis in acute myeloid leukemia.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive myeloid malignancy which characteristically expresses an atypical phenotype including CD123+, CD56+, and CD4+. We are aimed to investigate the clinical and prognostic characteristics of AML patients exhibiting BPDCN-like immunophenotype and provide additional insights for risk stratification of AML. A total of 241 newly diagnosed AML patients were enrolled in this retrospective study and categorized into BPDCN-like positive (n = 125)/negative (n = 116) groups, determined by the present with CD123+ along with either CD56+ or CD4+, or both. Subsequently, an analysis was conducted to examine the general clinical characteristics, genetic profiles, and prognosis of the two respective groups. Patients with BPDCN-like immunophenotype manifested higher frequencies of acute myelomonocytic leukemia and acute monoblastic leukemia. Surprisingly, the presence of the BPDCN-like immunophenotype exhibited an inverse relationship with CEBPA bZIP mutation. Notably, patients with BPDCN-like phenotype had both worse OS and EFS compared to those without BPDCN-like phenotype. In the CN-AML subgroups, the BPDCN-like phenotype was associated with worse EFS. Similarly, a statistically significant disparity was observed in both OS and EFS within the favorable-risk subgroup, while only OS was significant within the adverse-risk subgrouMoreover, patients possessing favorable-risk genetics without BPDCN-like phenotype had the longest survival, whereas those who had both adverse-risk genetics and BPDCN-like phenotype exhibited the worst survival. Our study indicated that BPDCN-like phenotype negatively associated with CEBPA bZIP mutation and revealed a significantly poor prognosis in AML. Moreover, the 2022 ELN classification, in combination with the BPDCN-like phenotype, may better distinguish between different risk groups.

Fms-like Tyrosine Kinase 3 Ligand Kinetic Profile Is the Strongest Factor Predicting Refractoriness after Induction and Event-Free Survival in Adults with AML: A Filo Prospective Multicentric Study

Background: Recently, a monocentric study has shown in adults with a non-previously treated acute myeloid leukemia (AML) that the stagnation of low levels of Fms-like tyrosine kinase 3 ligand concentration (FLc) in plasma, up to day 22 after an intensive induction, was associated with refractoriness and lower survivals (Peterlin et al, 2021). The present study wanted to confirm these results prospectively on a larger cohort of patients and in a multicentre way. Methods: This was a prospective non-interventional multicentre investigator sponsored trial (FLAMVAL study, clinicaltrials.gov: NCT04641910. One of the main objective was to study the impact on various outcomes of FL levels, evaluated during an intensive induction, in adults (>=18 year (y) old) with a non-previously treated non-M3 AML. Patients could receive a standard intensive induction chemotherapy combining anthracycline + cytarabine as part of a trial or not. Outcomes to be studied were responses, 1y overall survival (OS) and event-free survival (EFS), and 1-y leukemia-free survival (LFS) and relapse in responders. Response was evaluated according to ELN2017 criteria at day+30 after induction. Using a new cytokine multiplex assay from Milliplex (MILLIPLEX®), FL levels (expressed in pg/mL) were evaluated at Day (D) 1, D8, D15 and D22 from Day 1 of induction. Results: Between June 2021 and August 2022, 226 patients from 16 FILO centres were included but 204 with full evaluation of FL levels (816 samples) were considered for analyses. Their characteristics are reported in Table 1. At the time of analysis (July 2023), 1-y OS, EFS and LFS were 87+-5%, 78.3+-6% and 59.8+-8%, respectively. Median [Q1-Q3] FLc were 1.22 [0-4.19] at D1, 13.83 [2.26-72.46] at D8, 128.55 [13.06-293.43] at D15 and 24.14 [4.60-155.14] at D22. The number of refractory patients was significantly higher for those patients with a FLc < median at Day 8 (30.4% vs 13.7%, p=0.01), D15 (35.6% vs 8%, p<0.001) and D22 (31.1% vs 12.9%, p=0.007). 1-y OS and LFS were similar between patients with a FLc < or >= median at the four times considered. This was true also for 1y-EFS at D1 and D22. However, 1-y EFS was significantly worse for those with a FLc < median at D8 (48.5 % (41-55) vs 31 % (25-37), p=0.004) and at D15 (47.6 (40-55) vs 31% (25-37), p=0.002). As reported before (Peterlin et al, 2021), all patients but 4 (with a decrease of levels all along) can be categorized according to three FLc kinetic profiles: i) sustained increase from days 1 to 22 (FLI group n=39, 19% of the cohort), ii) increase from days 1 to 15, then decrease at day 22 (FLD group, n=86, 42% of the cohort) and iii) stagnation of low levels all along (<100 pg/mL from days 1 to 22, FLL group, n=75, 37% of the cohort). OS and LFS were similar between these three groups while 1-y EFS was significantly lower for the FLL group (45% [33; 57]) compared to FLI and FLD groups (64% [49; 79] and 71% [ 61; 80], p<0.001) ( Figure 1). This difference was due to a higher proportion of refractory patients in the FLL group (n=45/75 42.7% vs FLI =5/39, 12.8% vs FLD n=8/86, 9.3%, p<0.001, 2 patients not evaluated for response). Similar incidence of relapse was observed for responders comparing the three groups. Interestingly, only 8.8% (n=11/125) of the FLI/FLD patients had a FLc level <100 pg/ml at both times D8 and D15, suggesting that a FLL status can be predicted as soon as D15. For multivariate analyses, we compared FLc kinetic profiles (FLL vs FLI/FLD) on one hand and FLc medians (D1 D8 D15 and D22) on the other hand with other factors associated with a p value <0.20 by univariate analyses. In both models, only FLc kinetic profile and medians together with ELN2017 classification were found to be independent factors predicting response and EFS. However, FLL status was the strongest factor associated with refractoriness (OR: 6.2, 95%CI: 2.94-13.73, p<0.001, ELN favorable vs Intermediate p=0.003, favorable vs adverse p=0.002) and lower EFS (OR: 2.58, 95%CI: 1.40-4.79, p=0.002, ELN p=0.01 and 0.004). Conclusion: This large prospective multicentre trial confirms that a stagnation of low levels of FLc during a first-line induction in adults with non-M3 AML is the strongest factor (above ELN classification) associated with refractoriness and lower EFS in these patients. The study suggests also that this simple test could be useful to envisage salvage therapy including allotransplant just after D15 of induction. Funding This study was funded by Astellas Pharma Inc.

Venetoclax Exposure Reduction in Venetoclax-Hypomethylating Agents Combination Is Feasible and Has the Same Efficacy in Patients with Acute Myeloblastic Leukemia. Experience of a Single Center

BACKGROUND The combination of venetoclax (VEN) and azacitidine (AZA) is the actual standard of care for patients with acute myeloid leukemia (AML) not eligible for intensive treatment ( Di Nardo et al. N Engl J Med 2020; 383:617-629). Despite being considered a low-intensity treatment, dose adjustments are frequently needed in this group of patients due to prolonged myelosuppression and increased incidence of infection. Reducing the duration of VEN administration might improve the safety profile, although its efficacy is still unknown in this setting. AIM We present the experience of the Institut Català d'Oncologia-Hospital Duran i Reynals in patients with AML treated with VEN in combination with hypomethylating agents (HMA) to evaluate the efficacy of VEN exposure reduction in patients who require VEN adjustment due to myelotoxicity. METHODS We retrospectively analyzed 68 patients with AML treated with VEN+HMA as a first-line or as salvage therapy between May 2019 and April 2023. We specifically evaluated patients in complete remission (CR) after 1 to 3 cycles of VEN combination who require VEN scheme shortening to 7 (low dose) or 14-21 (intermediate dose) days every 28 days cycle due to myelotoxicity. Response to treatment was defined according to ELN2022 criteria. RESULTS Median age at diagnosis was 75 years (range 33-85 years). Forty-seven (69%) were male. Twenty-eight (41.2%) were classified according to the 2022 ELN classification as an adverse risk, 33 (48.5%) as intermediate risk and 7 (10.3%) as a favorable risk group. The median number of cycles was 7 (range 1-23). ORR of the whole series was 76.5%. Forty-six (67.6%) patients achieved a composite complete response (CRc) (CR, CR with partial hematologic recovery, and CR with incomplete hematologic recovery). Among the 46 responding patients, seven of them (15.2%) discontinued treatment because of patient's decision after achieving CR and they were not considered for further analysis. The remaining 39 patients reached the best response in the first 2 cycles. Twenty-eight (71.8%) patients received VEN+HMA as first-line treatment and 11 (28.2%), as salvage therapy. No significant differences were found between these two groups regarding sex, age or ELN2022 risk. Nine out of these 39 patients (23.1%) received VEN for 28 days every 28 days cycle (VEN28 group), 21 (53.8%) patients received VEN for 14 or 21 per cycle (VEN14-21 group), and 9 (23.1%) patients received VEN for 7 days per cycle (VEN7 group). With a median follow-up of 18.8 months (range 14.6-23.1), the median OS of the VEN14-21 group was 15.9 months but it was not reached for the VEN7 group. Regarding EFS, the median EFS of the VEN14-21 group was 11.4 months though it was not reached for the VEN7 group. No statistically significant differences were found comparing OS and EFS between the VEN14-21 group and the VEN7 group nor were both of them with the VEN28 group (Figure 1). CONCLUSION Shortening VEN exposure to 14-21 or 7 days per cycle with concomitant HMA administration seems to induce a similar response rate and is likely to have comparable efficacy to the 28-day cycle. Among responders, VEN dose reduction seems to be associated with favorable outcomes. Prospective clinical trials that further evaluate the efficacy and safety of shortened VEN administration are required.

Safety, Pharmacodynamic, and Anti-Tumor Activity of SL-172154 As Monotherapy and in Combination with Azacitidine (AZA) in Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML) and Higher-Risk Myelodysplastic Syndromes/Neoplasms (HR-MDS) Patients (pts)

Background: CD47 blocking antibodies and SIRPα-Fc fusion proteins have demonstrated activity in combination with azacitidine (AZA) in previously untreated (UnTx) HR-MDS and AML pts. SL-172154 (SIRPα-Fc-CD40L), a hexameric, bi-functional fusion protein consisting of SIRPα domains linked to CD40L domains through an inert Fc linker demonstrated improved anti-tumor activity in comparison to naked CD47 blocking antibodies in pre-clinical studies [de Silva et al. Cancer Immunol Res 2020]. SL-172154, as a CD47 inhibitor, requires combination with AZA to enhance pro-phagocytic signals on leukemic stem cells/blasts thereby potentiating macrophage phagocytosis in AML/HR-MDS. Here we report the results from the Phase 1 Dose Escalation. cohorts for SL-172154 monotherapy [SL-mono] and for SL-172154 + AZA combination [SL-AZA] in pts with HR-MDS or AML. Methods: The objectives of the dose escalation cohorts include evaluation of safety, dose-limiting toxicity (DLT), recommended phase 2 dose, pharmacokinetic and pharmacodynamic effects and efficacy per IWG 2006 for MDS and ELN 2017 for AML. SL-172154 was administered IV weekly of a 28-day cycle as monotherapy or with AZA 75 mg/m 2 for 7 days per cycle. mTPI-2 was used for dose escalation with a DLT threshold of 20%. Pts ≥ 18 years old with R/R HR-MDS or R/R AML were eligible for dose escalation cohorts. In addition, UnTx pts with TP53 mutant (TP53m)-MDS were eligible for SL-AZA cohorts. Results: As of May 25, 2023, 37 pts were enrolled (19 in SL-mono; 18 in SL-AZA cohorts): 14 women; median age 70 years [range 44-81]. 27 pts had R/R AML (16 de novo; 11 secondary), 5 had R/R MDS, and 5 were UnTx TP53m-MDS. 23 (85%) of 27 R/R AML pts had adverse genetic abnormalities per 2017 ELN classification, including 9 (33%) with TP53m or del 17. The median number of prior lines of AML therapy was 2 [range 1-4]; 25 (93%) had received venetoclax (VEN) and 23 (85%) had received a hypomethylating agent (HMA). All 5 pts with R/R MDS had previously received HMA and 2 pts were previously treated with VEN. SL-172154 was dose escalated as monotherapy or with AZA as shown in Table 1. Infusion-related reactions (IRRs) were the most common SL-172154-related treatment-emergent AEs (TEAEs) reported in 13 (68%) and 8 (44%) pts in SL-mono and SL-AZA cohorts, respectively. IRRs (51 events) were Grade (G) 1 or 2 except for 3 G3 events (1 each at 6 mg/kg SL-mono and SL-AZA; 1 at 3 mg/kg SL-mono). Other SL-172154-related TEAEs observed in ≥ 3 pts were AST increased (4; 21%), ALT increased (3; 16%) and nausea (3; 17%) in SL-mono cohorts, and nausea (3; 17%) in SL-AZA cohorts. All events of AST/ALT increased were transient. Only one DLT (G3 IRR in the 6 mg/kg SL-AZA cohort) was reported, which required a dose reduction to 3 mg/kg. As of July 10, 2023, in SL-mono cohorts, 1 pt with R/R AML post 7+3, FLAG and VEN/AZA achieved Morphologic Leukemia-Free State (blast reduction from 19% to <5%) after 1 cycle of 6 mg/kg SL-172154 and proceeded to allogeneic hematopoietic cell transplant (allo-HCT) after cycle 2. In 12 evaluable pts with R/R AML receiving SL-AZA, although no objective responses (OR) were observed, relative reduction in bone marrow (BM) blasts from baseline was reported in 2/5 pts at 1 mg SL-AZA (-50%, -75%) and 5/7 pts at 3 mg SL-AZA (ranging from -35% to -90%). One pt underwent an allo-HCT. In 4 evaluable pts with UnTx TP53m-MDS, the ORs were 1 complete remission (CR), 1 marrow CR, and 2 stable disease. 2 of them proceeded to allo-HCT. SL-172154 induced elevations in serum IL-12p40, IP-10, IL-8, IL-10, MIP3α and MCP1: greater response at 3 mg/kg compared to 1 mg/kg while similar between 3 and 6 mg/kg. In the BM, SL-172154 induced a dose-dependent increase in phagocytic cells (CD11b, HLA-DR, CD16, CD36 and CD64) within mature myeloid immune cell compartments (CD45highCD34-). Reduction in leukemic blasts (CD45lowCD34+) was associated with an increase in mature myeloid and phagocytic cell phenotypes (3 mg/kg SL-AZA > 1 mg/kg SL-AZA). Conclusions: SL-172154 was well tolerated up to 3 mg/kg as monotherapy and in combination with AZA. Preliminary efficacy signals were detected in UnTx TP53m-MDS and R/R AML. A response to SL-172154 monotherapy, dose-dependent increases in serum cytokines and accumulation of mature myeloid cells in BM suggest a potential role for CD40 stimulation. Based on the safety, preliminary efficacy and pharmacodynamic activity, 3 mg/kg SL-172154+ AZA is being evaluated in treatment naïve pts with TP53m AML and HR-MDS.

Tyrosine Kinase Inhibitors with Intensive Chemotherapy in AML with t(9;22)(q34.1;q11.2)/ BCR::ABL1: Time to Reconsider Prognostic Risk? a Study from the Dataml Registry

Introduction De novo AML with t(9;22)(q34.1;q11.2)/ BCR::ABL1 is now a distinct entity of the ICC and WHO 2022 classifications within the group of AML with defining genetic abnormalities. This entity is distinguished from cases with history of chronic myeloid leukemia (CML) and ≥ 20% blasts, which are classified as CML in myeloid blast phase (CML-BP), although the distinction between both entities could be challenging. In the 2022 ELN classification, AML with BCR::ABL1 belong to the adverse risk group. However, this entity is very rare and generally excluded from clinical trials. Thus, there is little data on outcome especially since the era of BCR::ABL1 inhibitors (Orsmark-Pietras C et al.). In this study, we thought to describe treatments and outcome of patients (pts) with de novo AML with t(9;22)(q34.1;q11.2)/ BCR::ABL1 in comparison with CML-BP and ELN 2017 intermediate (Int) or adverse (Adv) risk AML. Methods Inclusion criteria were: pts aged ≥ 18y, included in the DATAML registry between 2000 and 2021, with either de novo BCR::ABL1 AML defined as no previous history of CML, no previous treatment with TKI and ≥ 20% blasts in bone marrow/blood or CML-BP defined as the occurrence of ≥ 20% blasts following the diagnosis of CML in chronic phase. Outcomes of pts with de novo BCR::ABL1 AML were compared with those of CML-BP pts and AML with ELN 2017 Int (n=643) or Adv (n=863) risk treated with intensive chemotherapy (IC) over the same period. A 50-gene NGS panel was retrospectively performed on available samples. Results We identified 20 pts with de novo BCR::ABL1 AML among 5819 AML (0.3%). We only studied the 18 pts who received IC. Their main characteristics were: female to male ratio (55.6%), median age (54y), extramedullary disease (47%) including splenomegaly (35%); high WBC at diagnosis; isolated t(9;22) (67%); p210 isotype (78%), mutations in ASXL1, RUNX1, NPM1, TET2, BCOR, BCORL1, DNMT3A, EZH2, IDH1, KDM6A, NF1, SMC1A, SRSF2, WT1. Comparisons with the 24 pts CML-BP who were treated with IC are shown in the Table. The main differences between both groups was a higher WBC and the presence of NPM1 mutation in de novo pts whereas ABL1 mutations were found in CML-BP only. Induction chemotherapy was mainly cytarabine and daunorubicin (45-90 mg/m²) combined with imatinib (median dose 600 mg, range 400-800). Only 2 patients did not receive imatinib because the drug was not available in 2000-2003. Those 2 pts achieved complete remission (CR) but subsequently relapsed and died from progression. Overall, 17 pts (94.4%) achieved CR or CR with incomplete hematologic recovery (CRi) after one or two induction cycles, one pt failed and there was no early death. Consolidation was mainly high dose cytarabine with imatinib and 12 pts received an allogeneic hematopoietic cell transplantation (alloHCT) in first CR/CRi with myeloablative or reduced intensity conditioning in 7 and 5 pts, respectively. Five pts received maintenance therapy with imatinib (n=4) or nilotinib (n=1). Of note, 4 of the 5 CR/CRi pts who were not transplanted in CR1 did not relapse. With a median follow-up of 76.3 months, median RFS was not reached and 2y-RFS was 82.4% (95%CI, 55-94). Median OS was not reached and 2-y OS was 77.4% (95%CI, 50.3-90.9). Of note, there were 3 late deaths at 48, 60 and 84 months unrelated to AML (1 lung cancer, 1 pancreatic cancer, 1 infection). CR/CRi rate was significantly higher in pts with de novo BCR::ABL1 AML(94.4%) compared with CML-BP (79.2%), AML with ELN 2017 Int (83.4%) or Adv (68.5%) risk (P<0.0001). RFS (median, CML-BP: 100.5 months, IQR 19.7-NR; ELN-Int: 20.6 months, IQR 7.2-115.3; ELN-Adv: 10.3 months, IQR 4.4-48.1; P<0.0001) and OS (median, CML-BP: 33.9 months, IQR 14.6-NR; ELN-Int: 26.9 months, IQR 10.3-117.3; ELN-Adv: 11.8 months, IQR 4.7-40.0; P<0.0001) were also significantly improved. 2-y OS was 77.4%, 57.0%, 53.7% and 33.4% in de novo BCR::ABL1 AML, CML-BP, AML with ELN2017 Int and Adv, respectively (P<0.0001) (Figure). Conclusion De novo AML with t(9;22)(q34.1;q11.2)/ BCR::ABL1 is a very rare event in AML classifications (<1%) with particular features. Pts treated with IC and imatinib have a high rate of CR, very low incidence of relapse and a remarkable OS rate that do not support the ELN2022 risk classification . Pts may have prolonged RFS and OS without alloHCT. Further studies are needed to confirm these results and reclassify these AMLs in the intermediate or even favorable group of the ELN 2022 classification.

Picalm::MLLT10 can Identify a New Subgroup of Acute Leukemias of Ambiguous Lineage with Unique Extramedullary Disease and Treatment Response

Background: Mixed-phenotype acute leukemias (MPAL), which is included in acute leukemias of ambiguous lineage (ALAL), can be classified as four different subtypes based on recurring genetic alterations including BCR::ABL, KMT2A and ZNF384 gene rearrangement as well as BCL11B activation. The 2022 WHO classification has already mentioned PICALM::MLLT10 fusions are also enriched in MPAL but need more data. In 2022 ELN classification, PICALM::MLLT10 was identified as acute myeloid leukemia (AML) with other rare recurring translocations but not ALAL. In addition, there is no separate classification for PICALM::MLLT10 in the new ICC classification. Therefore, it is still confused whether PICALM::MLLT10 corresponds to AML or acute lymphoblastic leukemia (ALL) or ALAL. Methods: Fourteen PICALM::MLLT10 positive patients of 390 AL patients (14/390, 3.6%) were identified by RNA sequencing (RNA-seq) in our center from 2020-2022, including 8 female and 6 male, with a median age of 33 years (16-50 years). These patients were newly diagnosed AL according to bone marrow morphology and immunology including 5 ALAL, 5 T-ALL [ 4 early T-cell precursor ALL (ETP-ALL), 1 cortical T-ALL], 2 AML, 1 B-ALL with aberrant expression of myeloid antigen, and 1 B/T MPAL. Results: The mean white blood cell counts of these patients was 8.25×10 9/L (2.34-51×10 9/L) and platelet counts was 168.5×10 12/L (39-429×10 12/L) individually. It should be mentioned that extramedullary disease (EMD) was found in 7 cases (7/14), including mediastinum, tonsil, and skin. In terms of immunotyping, CD7 was identified in all patients (14/14) and CD33 in 71.4% (10/14) patients. The major concurrence mutations were PHF6 mutation (8/14), JAK3 mutation (5/14), and SUZ12 mutation (4/14). Characteristic cytogenetic abnormality t(10;11)(p12.3;q14.2) was only found in three cases (3/14) (Table 1). The PICALM breakpoints are mainly concentrated in exon 17 (n=6) and exon 19 (n=8). Exon 4 (n=8), exon 6 (n=2), exon 9 (n=2) and exon 10 (n=2) are the most commonbreakpointsof MLLT10. To our knowledge, this is the first report about the breakpoints and fusion gene forms of PICALM::MLLT10. For initial treatment, these patients individually received standard ALL induction chemotherapy (VDPCP, vincristine, idarubicin, pegaspargase, cyclophosphamide, prednisone) and AML induction chemotherapy (3+7 IA regimen including idarubicin, cytarabine). The initial complete remission (CR) rate was only 35.7% (5/14), and 9 patients showing no remission (NR). These NR patients subsequently received salvage chemotherapy. It is worth mentioning that 6 of them received combined chemotherapy regimen including low doses of cytarabine (LDAC), granulocyte colony-stimulating factor (G-CSF) and anthracyclines such as aclarubicin or idarubicin or homoharringtonine (CAG or IAG or HAG), and 2 of 6 patients also further received combination therapy with venetoclax (CAG or IAG +VEN). Finally, 5 of them dramatically achieved CR (5/6). In the other 3 patients, 1 patient who was failure to initial Hyper-CVAD A/B regimen also dramatically achieved CR after the more Hyper-CVAD A regimen combined with venetoclax, and 1 patient achieved CR while another still NR with both receiving CLAG (cladribine, cytarabine, G-CSF) regimen. Subsequently 11 patients (9 CR, 2 with refractory disease) received allogenic hematopoietic stem cell transplantation (allo-HSCT), and all the CR patients survived well after HSCT (follow up 3-24 months, median 15 months) without relapse, while 2 NR patients died soon after transplantation because of severe complications (Table 2). Conclusions: Our data suggested PICALM::MLLT10 positive AL should be more appropriately recognized as an independent ALAL entity and may benefit from LDAC, G-CSF and anthracyclines combination chemotherapy as well as venetoclax. Sequential HSCT after chemotherapy combined with venetoclax may further improve long-term survival in AL patients with CR even MRD positive.

Gemtuzumab Ozogamicin for Patients with Newly Diagnosed CD33 Positive Acute Myeloid Leukemia: Results from a French Retrospective Observational Study

Introduction: Gemtuzumab ozogamicin (GO) is an antibody-drug conjugate targeting CD33 with a calicheamicin derivative payload. GO is approved in France in combination with daunorubicin and cytarabine for treatment-naïve patients aged ≥15 years with de novo CD33-positive acute myeloid leukemia (AML). Before the European Medicines Agency granted marketing authorization in 2018, GO was available in France with an authorization for temporary use (ATU) for specific patients since 2010, and between 2018 and 2019 as part of a “post-ATU” cohort until its reimbursement. This study aimed to describe the real-world use, effectiveness, and safety of GO in treatment-naïve patients with CD33-positive AML in France, as requested by the French Transparency Commission. Methods: This retrospective, multicenter, observational study included all patients in the French ATU and post-ATU cohorts treated between 01 December 2014 and 31 October 2022. Patient and disease characteristics, treatment (dose/combination), response outcomes, and adverse events (AEs) of interest were described. Prognostic factors for event-free survival (EFS), relapse-free survival (RFS), and overall survival (OS) were identified using Cox proportional hazard models. Results: Overall, 113 patients were included (ATU cohort, N=62; post-ATU cohort, N=51). The median age when GO was initiated was 63.0 years (range, 19-91); 54.9% (n=62) of patients were male; 81.8% (n=72/88) had an ECOG performance score 0-1, and 65.3% (n=64/98) had favorable risk according to the ELN classification 2017 ( Table). During the first induction treatment, most patients (98.1%; n=105/107) received GO in association with other agents, most commonly cytarabine and daunorubicin (60.0%; n=63/105). Most patients (78.5%, n=84/107) received 3 doses of GO during first induction. In all cases, patients received GO in second (7.1%; n=8) or subsequent (2.7%; n=3) induction courses - always in association with cytarabine and with or without daunorubicin/other agents. GO was given during the first, second, and subsequent consolidation treatment in 46.9% (n=53), 32.7% (n=37), and 2.7% (n=3) of patients, respectively, usually with cytarabine with or without daunorubicin. After a median follow-up of 44.6 months (95% CI, 33.8-69.3), 78.6% (n=88/112) of patients responded post-induction - of these, 72.3% (n=81) achieved a complete response (CR) and 6.3% (n=7) achieved a CR without platelet recovery. Minimal residual disease was evaluable in 46 patients; 52.2% (n=24) achieved a CR without minimal residual disease. Median EFS was 13.1 months (95% CI, 9.9-17.5); EFS by ELN risk group is shown in the Table. Median RFS was 17.5 months (95% CI, 12.6-35.6) and median OS was 49.8 months (95% CI, 21.8-not estimable; Figure). After a median period of 13.0 months (range, 3.0-33.0) following GO treatment, 31.5% (n=35/111) of patients received a hematopoietic stem cell transplant. Older age predicted shorter OS (hazard ratio [HR] 1.1 [95% CI, 1.0-1.1]; p<0.001). Having an FLT3TKD mutation (HR 4.1 [95% CI, 1.4-12.4]; p=0.013) or adverse cytogenetic classification (HR 13.0 [95% CI, 2.3-73.8]; p=0.015) predicted shorter EFS. Having ECOG-PS ≥2 (HR 6.6 [95% CI, 1.8-24.5]; p=0.005) or adverse cytogenetic classification (HR 72.7 [95% CI, 7.6-699.1]; p=0.001) predicted shorter RFS. AEs of interest were reported for 38.9% (n=44) of patients; 13.3% (n=15) were serious and 26.6% (n=30) were treatment-related (TRAE). The most common AEs were thrombocytopenia (21.2%; n=24), pyrexia (4.4%; n=5), and hepatic cytolysis (3.5%; n=4). AEs of special interest included persistent thrombocytopenia (15.9%; n=18), severe hemorrhage (5.3%; n=6), and veno-occlusive disease/sinusoidal obstruction syndrome (0.9%; n=1). Overall, 46.9% (n=53) patients died, with relapse or progressive disease accounting for 41.5% of deaths (n=22/53). Two (1.8%) patients died from TRAEs (laryngeal edema/pulmonary alveolar hemorrhage and hepatic cytolysis). Conclusions: GO was predominantly administered according to its indication. Response rates were similar to those reported in the pivotal ALFA-0701 study. Median OS was longer in this study than in ALFA-0701 (49.8 vs 27.5 months), although median RFS and EFS were reduced. No new safety signals were reported. Overall, GO appears safe and effective in real-world practice when added to induction therapy for treating patients with de novo CD33-positive AML.

Prognostic Impact of Clonality of Myelodysplasia-Related Gene Mutations in AML

Introduction: The 2022 International Consensus Classification (ICC) stresses the importance of molecular- and cytogenetic aberrations over previous medical history. Nine mutations are used to define a subgroup of AML with myelodysplasia related gene mutations (AML-MRGM). On a lower hierarchical level specific cytogenetic changes are used to define a subgroup of AML with myelodysplasia related cytogenetic abnormalities (AML-MRCA). Both groups together with TP53 mutations are categorized within the adverse risk group of the 2022 ELN classification. We evaluated the prognostic implications of clonality of MRGM mutations. Methods: 552 newly-diagnosed adult AML patients (pts.) with a median age of 55 years who received intensive induction chemotherapy followed by consolidation chemotherapy or allogeneic stem cell transplantation and with available genetic and follow-up data were included. Mutations present at diagnosis were identified by Illumina myeloid panel sequencing covering 48 AML-associated genes. Variant allele frequency (VAF) was adjusted for sex for mutations located on the X chromosome (BCOR, STAG2, ZRSR2). The prognostic VAF cutoff was identified by maximally selected rank statistics. We defined AML-MRGM as having at least one MRG mutation, AML-MRCA as having at least one MRCA without MRGM, TP53 mutated patients as having TP53 mutations regardless of the presence of MRGM or MRCA and for the remaining pts. de novo AML and secondary/therapy-related AML according to medical history of the patient. For multivariate analysis value imputation was used for missing values. Results:40 (7.2%) of 552 pts. were TP53 mutated,196 (35.5%) had at least one MRGM, and 47 pts. (8.5%) had MRCA. Among the clinically defined cases 215 pts. (38.9%) had genuine de novo AML and 54 (9.8%) had a previous history of a hematologic malignancy or cytotoxic treatment. The median follow-up was 5.8 years. Overall survival (OS) and relapse free survival (RFS) for de novo AML and secondary AML based on medical history were not significantly different and were therefore grouped together as clinically-defined AML (cdAML). AML-MRGM pts. had a significantly lower complete remission (CR) rate (OR=0.32, 95%CI 0.18-0.56, p<0.001) and shorter OS, but not RFS, compared to cdAML pts. (OS, HR 1.38, 95%CI 1.04-1.83, p=0.02; RFS, HR 1.12, 95%CI 0.84-1.48, p=0.44). AML-MRCA had similar OS and RFS compared to both cdAML and AML-MRGM pts., but a significantly better CR rate than AML-MRGM pts. (OR 5.68, 95%CI 1.64-38.65, p=0.01). Pts. with TP53 mutations had a worse OS and RFS than all other subgroups. A VAF of 45% was identified as a prognostic cutoff by maximally selected rank statistics. Patients with MRGM and VAF ≥ 45% were associated with higher age (p=0.04) and a lower platelet count at diagnosis (p=0.04). A VAF ≥ 45% was identified in 81 pts. (41.3%) and was associated with a significantly worse OS and RFS compared to the 115 pts. (58.7%) with a VAF below 45% (OS, HR 1.70, 95%CI 1.12-2.57, p=0.01; RFS, HR 1.65, 95%CI 1.05-2.57, p=0.03) (Figure 1). Patients with VAF ≥ 45% had an OS and RFS similar to AML-MRCA pts., but significantly shorter OS and RFS than cdAML pts. (OS, HR 1.89, 95%CI 1.32-2.69, p<0.001; RFS, HR 1.52, 95%CI 1.04-2.21, p=0.03). In multivariate analysis the presence of MRGM with a VAF ≥45% was an independent adverse prognostic factor for OS. Conclusion: In the present study, we confirm myelodysplasia-related gene mutations and TP53 mutations as negative prognostic markers in line with the hierarchical significance proposed by ELN. Our study suggests that the presence of MRGM is associated with worse OS especially if it is present at a VAF ≥ 45%, likely representing patients with at least one MRG mutation in the major AML clone.

The ELN 2022 Risk Stratification Has No Impact on the Dismal Prognosis of Patients with Acute Undifferentiated Leukemia

Introduction: Acute undifferentiated leukemia (AUL) is a rare subtype of acute leukemia. It is characterized by lack of expression of myeloid or lymphoid lineage markers, frequently expressing CD56 or CD7. The dismal prognosis of AUL was reported in small studies; the largest previously reported group with this disorder included 24 patients (Weinberg, Mod Pathol, 2019). Furthermore, data are lacking regarding cytogenetic and molecular patterns of AUL. In this study, the cytogenetic and molecular changes of AUL patients are described, together with the clinical outcome. Methods: AUL was defined, in accordance with the WHO classification, as an acute leukemia that does not qualify for myeloid, B- or T-cell lineage. Immunophenotyping of BM cells at diagnosis was performed using 8-color flow cytometry. Multi-parameter Cytognos acute orientation tube (ALOT) and the combination of the following antigens were used: CD34/CD117/CD14/CD56/CD36/CD123/HLA-DR/CD45/CD64/CD11c. (Weinberg, Mod Pathol, 2019). Results: Three hundred and eighty-five patients with acute myeloid leukemia (AML) were diagnosed at Rambam Health Care Campus in Haifa, Israel between April 2015 and April 2021, of whom 30 (8%) were defined as AUL. The baseline characteristics are presented in Table 1. The median age was 62 years, none of the patients harbored NPM1 mutation, with 1 patient expressing FLT3-ITD mutation. Cytogenetic analysis was completed for all patients: 9 (30%) had adverse-risk cytogenetics by ELN 2022 criteria. A comprehensive molecular study using molecular inverted probe was performed on all patients, with final results available on 17. Nine of these 17 (53%) had high-risk mutations; RUNX1 was found in 4 patients. Notably, 4 other patients had JAK2 mutation, with or without previous myeloproliferative neoplasm. Only 3 patients had mutations characterizing secondary AML (Lindsley, Blood, 2015). Only 2 patients in this cohort had TP53 mutation or del17p. Fourteen patients were classified as adverse-risk AML by ELN 2022 using cytogenetic and molecular markers, while 15 were classified as intermediate risk. Only 4 patients in this adverse-risk cohort were not allogeneic hematopoietic stem cell transplant (HSCT) candidates due to age or comorbidity limitations. The outcome of the cohort is presented in Table 2. Twenty-two fit patients received 7+3 intensive chemotherapy, of whom 10 achieved complete remission (CR) after induction. Four of the 10 patients needed reinduction chemotherapy due to a high blast count on the bone marrow performed at day 14. Five patients were treated with low-intensity therapies such as hypomethylating agents ± novel agents; 2 achieved CR. One patient received FLAG-Ida chemotherapy and another patient was treated with ECOG1910 protocol due to clinical presentation more compatible with acute lymphoid leukemia; both achieved CR. Of the 14 patients achieving CR, 4 relapsed before HSCT and needed further salvage therapy. Eventually, 13 (50% of the transplant-eligible candidate cohort) patients proceeded to HSCT. Relapse occurred in 14 patients (10 post-HSCT and 4 before HSCT), none of them achieved long-term survival. Four of the 30 patients are alive, all in remission. The median overall survival of the entire cohort is 1 year (Fig 1). The outcome of patients with adverse or intermediate risk according to the ELN risk classification did not differ. The CR rate and relapse rate and median overall survival (OS) were similar in both groups (Table 2; Fig 1). Discussion: These data emphasize the dismal outcome of patients diagnosed with AUL, with the 5-year OS of 7.5%, far lower than the survival of other types of acute leukemia. In this cohort, 15 patients were classified as intermediate risk AML; yet, their CR rate and long-term survival were not different from the whole cohort. The CR rate achieved with the widely used 7+3 protocol, was inferior, raising the question whether this protocol should be the “standard of choice” in such patients. A limitation of this study is that not all patients were evaluated by the NGS panel, bringing about the issue whether more patients had high-risk mutations, who would then be classified as adverse risk. Conclusion: The unique subtype of AUL is associated with a particularly adverse risk genotype, irrespective of known prognostic determinants, as in the 2022 ELN classification.

A Comparison of Somatic Mutations and ELN Classification in De Novo Acute Myeloid Leukemia between Appalachian and Non-Appalachian Kentucky

Introduction The Appalachian region's cancer mortality rate is 10% higher than the national rate. Central Appalachia, which is predominantly in Kentucky, exceeds the national average by 35%. Appalachian Kentucky has higher mortality rates for prostate, lung, cervical, and head and neck cancers compared to non-Appalachian Kentucky. This can be attributed to health care disparities, environmental factors, and unique genomic characteristics of the tumors seen in the Appalachian population. Based on this, we hypothesized that patients with acute myeloid leukemia (AML) in Appalachian Kentucky would have worse outcomes and higher mutational burden compared to patients in non-Appalachian Kentucky. To test this hypothesis, we compared overall survival (OS) and frequency of molecular mutations between patients from Appalachian (ApK) and Non-Appalachian Kentucky (Non-ApK). Methods A single-center retrospective analysis was done utilizing the Kentucky Cancer Registry (KCR) to identify patients with De Novo AML from January 2015 to January 2021. Patients with available cytogenetic and somatic mutations profile from next-generation sequencing (NGS) were included. Demographic, clinical, laboratory, and pathologic data were obtained from clinical records. Statistical analysis was done using the Mann-Whitney U test for continuous variables and proportions were compared using Chi-square test. The Kaplan-Meier curves were used for overall survival. Results A total of 225 patients with de novo AML were identified. The median age at diagnosis was 61 (range, 21-86). The population was fairly distributed among males (52%) and females (48%). Approximately 56% (n=127) of patients were from ApK and 46% (n=98) were from non-ApK. Of the patients from ApK, approximately 22% (n=29) had favorable risk AML per the ELN 2022 classification, while 24% (n=30) had intermediate and 54% (n=68) had poor risk AML. This was not statistically different from the Non-ApK patients where 22% (n=22) had favorable, 21% (n=21) had intermediate, and 56% (n=55) of patients had poor risk AML (Table 1). The median number of clinically significant mutations were also similar between the two groups (p value = 0.47). The most commonly occurring somatic mutations were NPM1, DNMT3A and FLT3-ITD, which occurred at similar frequencies between the ApK and non-ApK cohorts. There was no difference in the median overall survival between the two cohorts (17 versus 22 months, p =0.47; 90% CI). Median OS and 1-year OS for the entire cohort were 21 months and 47.1%, respectively. Conclusions This study demonstrated that the outcomes of de novo AML is similar for patients from Appalachian versus Non-Appalachian Kentucky when treated at an Academic Medical Center. There were no statistically significant differences between ELN 2022 risk classification and mutational abnormalities tested between these two groups. This suggests that the biology in de novo AML is similar in both ApK and non-ApK patients.

Updated Results from a Phase I Dose Escalation Study of the Rapidly-Switchable Universal CAR-T Therapy UniCAR-T-CD123 in Relapsed/Refractory AML

Introduction CAR-T efficacy in AML has been limited by a lack of ideal target antigens as well as the aggressive and resistant nature of disease. CD123 expression on leukemic blasts has been observed in about 80% of AML patients. However, the antigen is also expressed on non-malignant hematopoietic cells including neutrophils and endothelial cells. As consequence, targeting of CD123 with conventional CAR-T has been shown to result in persistent cytopenias, capillary leakage syndrome, CRS, and ICANS. AVC-101 (UniCAR02-T-CD123) is an adapter CAR-T, consisting of a universal CAR-T cell (UniCAR-T) and a CD123 targeting module (TM). The TM binds to the CAR-T cell via a peptide tag and induces T cell activity against CD123 bearing cells. Due to the short half-life of the TM, interruption of its continuous IV administration will rapidly switch T cell activity off, and mitigate toxicities as shown previously. Since the presentation of initial results, the study was amended to include a stricter and prolonged schedule of TM consolidation cycles. Given the excellent safety enabled by the switchable mechanism, additional dose levels (DL) of TM were added. Methods Key inclusion criteria included rrAML patients with ECOG ≤ 1, CD123 expression in ≥ 20% of blasts, and no suitable approved treatment option available or MRD positive AML patients. Initial dosing was applied using an adaptive Bayesian optimal interval design for drug-combination trials, escalating either cell dose or TM concentration based on posterior probability calculation of AEs. Dose escalation for the two additional dose levels was guided by a classical 3+3 design. Patients received standard Flu/Cy lymphodepletion (LD) for 3 days and TM was administered as continuous infusion, whereas UniCAR-T cells were given as one-time infusion on cycle 1 day 1. After completion of the initial 20-day induction cycle, responding patients were allowed to receive up to 3 consolidation cycles of 12 days continuous TM infusion with 7-14 days treatment free intervals in between cycles. Results As of this time 19 patients have received the induction cycle, 8 patients have also received at least one consolidation cycle (1-3, total 13 cycles). Patients were heavily pretreated with a median of 4 (2-7) prior treatment lines. Twelve of these patients had received a prior allogeneic (Allo) stem cell transplantation (SCT). Most of the patients (60%) were in adverse risk category according to ELN classification. In the initial escalation phase, 19 patients were treated in 16 dose cohorts. We observed a single DLT at DL 8 (reversible drop in fibrinogen levels, reported earlier) but no DLTs occurred in 11 patients treated in the yet highest dose cohort of 4 mg/day TM and 500 million UniCAR-T. Treatment was generally well tolerated irrespective of age and prior treatments. CRS was observed in 12 patients, mostly grade 1 or 2. Three grade 3 CRS and 1 grade 2 ICANS were reported, all resolving within 24 hrs from interruption of TM administration. Treatment-related AEs were most frequent in cycle 1, none were reported in cycles 3 and 4. No treatment-induced lasting myelosuppression was observed, and no patient required SCT support for WBC reconstitution. ORR in the first 19 patients was 53% (8/15) for the rrAML population and 75% (3/4) for the MRD population. Since the last presentation, extended administration of TM (20-day induction followed by three 12-day consolidation cycles 1-2 weeks apart) initiated by protocol amendment resulted in durable, ongoing responses approaching 5 months, longer than any prior. A 64-year-old MRD+ patient (#19) with 4 prior lines of therapy experienced a 3-log reduction in MRD levels (NPM1 mutation by qPCR) in both bone marrow and blood (Figure 1) and became transplant eligible. Re-administration of TM resulted in a significant re-expansion of UniCAR-T (Figure 2) without further cell dosing or LD. Another patient (#20) with overt hematological relapse after AlloSCT achieved a CR, ongoing at 5 months. Full safety and efficacy results of the additional 2 dose cohorts with prolonged TM consolidation will be presented at the meeting. Conclusions AVC-101 continues to be safe and tolerable. Repeated dosing of TM in consolidation cycles resulted in robust re-expansion of UniCAR-T with deeper remissions of extended durability. The switchable mechanism provides proven rapid reversal of safety events, enabling higher dose levels.

LONG-TERM Outcomes after Venetoclax-Hypomethylating Agent Combination Therapy Discontinuation, in Patients with ACUTE Myeloid Leukemia. Experience of a Single Center

CONCLUSION The combination of azacitidine and venetoclax has become the standard of care in patients with acute myeloid leukemia (AML) who are not eligible for intensive chemotherapy ( Di Nardo et al. N Engl J Med 2020; 383:617-629). Despite being considered a low-intensity treatment, long-term administration of venetoclax based combinations treatment can be challenging due to a multitude of factors, ranging from drug-related toxicity to logistical and quality of life obstacles often bringing to dose adjustments or discontinuation. We analyzed long-term outcomes of patients with AML treated with venetoclax in combination with hypomethylanting agents who required discontinuation of treatment, after reaching complete remission (CR), due to toxicity or patient decision treated at the Institut Català d'Oncologia-Hospital Duran i Reynals. Observational and retrospective study that includes patients diagnosed with AML who received treatment with venetoclax in combination with hypomethylating agents as first line or as salvage therapy, between May 2019 and April 2023. Bone marrow was analyzed pre-treatment for somatic mutations via targeted next-generation sequencing (NGS). 68 patients were included in the study. The median age at diagnosis was 75 years (range 33-85 years), with a predominance of males (69%). Twenty-eight (41.2%) patients were classified according to the 2022 ELN classification as an adverse risk, 33 (48.5%) as intermediate risk and 7 (10.3%) as a favourable risk subgroup. Forty-eight (70.6%) patients received the combination as first line treatment and 20 (29.4%) as salvage therapy. No significant differences were found between the two groups regarding sex, age or ELN2022 risk. The median number of cycles received was 7 (range 1-23 cycles). The overall response rate (ORR) was 76.5% (52 of 68 patients), of which 46 (68%) patients achieved a composite CR (CRc) (CR, CR with partial hematologic recovery, and CR with incomplete hematologic recovery). Among the 52 responding patients, 88.5% of the patients obtained the best response in the first 2 treatment cycles. Median overall survival (OS) and event-free survival (EFS) of the series were 12.7 and 10.9 months, respectively. 30 days mortality was 7.7% (3 patients due to infectious event and 1 patient due to progression). Seven of the 52 responding patients (13.5%) discontinued treatment after achieving CRc. The median number of cycles received prior to discontinuation was 2 (range 1-11 cycles). The reasons for treatment discontinuation were: patient decision (4), grade 4 myelotoxicity (2) and recurrent infections (1). Pre-treatment NGS data (n=7) from the patients who discontinued the treatment showed a median of 4 (range 2-9) mutations with a predominance of mutations in genes that encode epigenetic modifiers ( DNMT3A n=4 and TET2 n=3). RUNX1 mutation was also frequently seen at diagnosis in 3 patients. The median follow-up from the end of treatment until last visit or dead was 8.1 (3.5-10.0) months. Two of the 7 patients have died during the treatment-free period, one of them due to non-haematological cause and the other one due to disease relapse. This last patient had a TP53 mutation (VAF 78%), and the observation period without treatment for this patient was 8.5 months. No other patients had a TP53 mutation. Median EFS and OS of patients who discontinued treatment were 7.3 and 8.5 months, respectively. No statistically significant difference was observed in OS of the responding patients according to treatment discontinuation or not (Figure 1). Our findings confirm the high efficacy of venetoclax and azacitidine combination in AML. Discontinuation of treatment in responding patients was associated with similar durable responses and OS compared to patients who continue under treatment. Identifying the subgroup of patients who may benefit from de-escalation strategies is mandatory. Further studies are needed to determine which patients might be appropriate for treatment suspension or discontinuation while in remission.

Safety and Efficacy of Outpatient Myeloablative Busulfan Conditioning in Allogeneic Stem Cell Transplantation

INTRODUCTION: Busulfan-based regimens are the backbone of myeloablative conditioning (MAC) in allogeneic hematopoietic stem cell transplant (allo-HSCT), particularly for patients (pts) with Acute Myelogenous Leukemia (AML). However, literature on busulfan conditioning administered in the outpatient (OP) setting is limited. Here, we investigate the safety and efficacy of OP busulfan as compared to standard inpatient (IP) administration. METHODS: Pts > 18 years of age who received pharmacokinetically dose adjusted IV busulfan (130 mg/m2 x 4 days) conditioning prior to HSCT between January 2019 and April 2023 at our institution were included in this retrospective analysis. Pts who received non-myeloablative conditioning or who underwent a haploidentical HSCT were excluded. All pts undergoing HSCT were classified as having low-, intermediate-, or high-risk disease by the Disease Risk Index. Pts with AML were classified as having favorable, intermediate, or adverse disease by 2022 ELN classification. CIBMTR guidelines were used to determine neutrophil and platelet engraftment. Oral mucositis was graded per the World Health Organization scale. Clinical grading of acute graft-vs-host disease (AGVHD) was assigned per standard criteria. Adverse events (AEs) were reported in accordance with the CTCAE, v.5. Categorical variables were compared using the Fisher's Exact test. Continuous variables were compared using the Wilcoxon Rank-Sum test. Overall survival (OS) was defined as time from HSCT to time of death from all-cause mortality. Relapse-free survival (RFS) was defined as time from HSCT to time of relapse or non-relapse mortality. The Kaplan-Meier method was used to estimate OS and RFS. Survival differences between cohorts were compared using the Log-rank test. All hypothesis testing was two-sided and conducted at a significance level of 0.05. RESULTS: In total, 54 pts met eligibility criteria; 43 IP and 11 OP. The OP cohort was younger than the IP cohort (35 years vs 47 years median age; p=0.0284). All other patient, disease, and transplant characteristics were similar between cohorts. The majority of pts were male (IP: 56%, OP: 55%) and White/Caucasian (IP: 100%, OP: 91%). AML (IP: 88%, OP: 82%) was the most common indication for HSCT. Most pts were in CR1 (IP: 74%, OP: 89%) and had intermediate risk disease by both DRI (IP: 84%, OP: 64%) and 2022 ELN classification (IP: 62%, OP: 67%). PBSCT (IP: 88%, OP: 91%) and 10/10 MUD (IP: 67%, OP: 45%) were the most common types of HSCT. The majority of pts received a conditioning regimen of Flu/Bu4 (IP: 58%, OP: 55%). The use of PTCy was comparable between groups (p=0.6593). Of the 11 pts who received OP busulfan, 1 had to complete their conditioning IP after experiencing a seizure in the setting of prior meningitis. Between the 2 cohorts, there was no significant difference in the incidence of AEs > grade 2 (p=1), grade 2 AEs (p=0.8695), grade 3 AEs (p=0.7592), grade 4 AEs (p=0.2487), and grade 5 AEs (p=0.6457) within 30 days of conditioning. Incidences of transplant-related GI toxicities, including nausea (p=1), vomiting (p=0.4979), diarrhea/enteritis (p=1), and mucositis (oral: p=0.6102, GI: p=0.2821) were similar. There was no difference in time to neutrophil (p=0.1606) or platelet engraftment (p=0.9742). Length of hospitalization was shorter in the OP vs IP cohort (18 vs 24 days; p<0.0001). During hospitalization, there was no difference in the incidences of neutropenic fever (p=1), infection (p=0.5104), ICU transfer (p=1), or engraftment syndrome (p=0.7076). Number of infections per patient during hospitalization were comparable (p=0.3764). D30 chimerism was similar IP vs OP. Within 180 days of HSCT, there was no difference in the incidence of AGVHD (p=0.5152) or Grade II-IV AGVHD (p=1). Differences in 2-year OS (LR=0.2200) and 4-year RFS (LR=0.3144) were not significant. CONCLUSION: In pts undergoing MAC allo-HSCT with IV busulfan,OP administration shortens the length of hospitalization without delaying engraftment or increasing the risk of toxicity, neutropenic fever, infection, or ICU admission. Additionally, D30 chimerism, rates of engraftment syndrome and AGVHD, and survival were not affected. This makes OP busulfan an attractive option for transplant centers and their pts.

Myelomonocytic/Monocytic Subtypes Are More Resistant to Venetoclax-Based Therapy in Acute Myeloid Leukemia Patients: A Monocentric, Real-Life Retrospective Study

Background： Venetoclax(VEN)-based regimens have seen broad adoption in newly diagnosed patients with acute myeloid leukemia (AML) who are not candidates for intensive induction chemotherapy. Nonetheless, a sizable proportion of AML patients do not respond. Finding biomarkers that can predict treatment results is crucial. FAB (French, American, British) classification system provides a well-described and clinically associated means to segregate AML patients by virtue of myeloid differentiation status. Whether FAB classification can be used as a predictor marker for VE-based therapy is controversial. In the Chinese population of patients with AML, we conducted this single center retrospective study to examine the predictive value of monocytic and myelomonocytic differentiation on the response to VEN-based treatment. Methods: The clinical features, treatment information, and clinical outcomes of AML patients who received at least one dose of VEN treatment at West China Hospital for more than seven days between January 1, 2019, and September 8, 2022 were retrospectively examined in this study. We classified the patients into two groups based on the FAB classification system: the primitive group (includes M0/M1/M2, abbreviated as PRI) and the myelomonocytic/monocytic group (includes M4/M5, abbreviated as M/M). AML response to VEN therapy was determined by the 2017 European Leukemia Net response criteria after one cycle of VEN treatment. The overall response rate (ORR) was defined as the combination of CR, CRi, PR. From the first day of VEN use until the patient dies or the end of follow-up, the overall survival (OS) time is calculated. Logistic regression and COX regression were used to examine the variables that influence ORR and survival. All statistical tests were two-sided, and p-values of 0.05 or lower were considered significant. All statistical analyses were performed using RStudio 4.2.2. Results: There were 267 patients in all, with 162 newly diagnosed (M/M n=69; PRI n=93) and 85 relapsed/refractory (M/M n=44; PRI n=41). The ORR for M/M is 63.77%, while that for PRI is 84.95% among newly diagnosed patients (p=0.018). The ORR for M/M is 40.91% and PRI is 68.29% among relapsed/refractory patients (p=0.0114, Figure1). In addition, we identified (i) FAB classification M/M subtypes, (ii) previously diagnosed MDS/MPN, (iii) IDH1/IDH2 mutations, (iv) relapsed/refractory event, (v) transfusion requirement, and (vi) TP53 mutation as significant factors predicting the response of all patients using univariate logistic regression analysis. M/M subtypes and MDS/MPN also trended toward independent predictors in the multivariate analysis. We identified (i) FAB Classification M/M subtype, (ii) adverse risk AMLs according to the 2022 ELN classification, (iii) CEBPA mutation, and (iv) TP53 mutation as significant factors predicting the risk of all patients using univariate COX regression analysis. M/M subtype and TP53 also trended toward independent predictors in the multivariate analysis (Table1). OS was significantly longer in the PRI than in the M/M(median OS: 621 days vs 266 days, hazard ratio 0.56, 95% CI: 0.39-0.80, p=0.0011). We compared the overall survival of various illness conditions; OS still was significantly longer in the PRI group than in the M/M group among newly diagnosed patients (median OS: newly diagnosed: 1124 days vs 295 days, HR: 0.47, 95% CI: 0.24-0.83, p=0.0017; refractory/relapsed: 204 days vs 266 days, HR 0.68: 95% CI: 0.45-1.97, p=0.72). Conclusion： Our research demonstrates that the response to VEN may differ depending on how advanced the AML is, with PRI patients being more sensitive and M/M patients being more resistant, particularly in newly diagnosed individuals. Previous research has discovered that AML cells with Monocyte/erythroid/Megakaryocyte differentiation are less sensitive to BCL-2 inhibition in vitro, indicating that the differentiation stage of AML may affect its sensitivity to BCL-2 family inhibitors. This is likely due to an increase in MCL1 family expression and a decrease in BCL2 family expression during cell differentiation. In conclusion, M/M subtype may be able to predict VENs resistance and the worse prognosis for patients treated with VEN-based regimens. Legends to figures Figure 1: Differences in ORR and NR (no response) between M/M and PRI in newly diagnosed and relapsed/refractory patients Table1: Regression analysis results

Clinical outcome of therapy-related acute myeloid leukemia patients. Real-life experience in a University Hospital and a Cancer Center in France.

t-AML occurs after a primary malignancy treatment and retains a poor prognosis. To determine the impact of primary malignancies, therapeutic strategies, and prognostic factors on clinical outcomes of t-AML. A total of 112 adult patients were included in this study. Fifty-Five patients received intensive chemotherapy (IC), 33 non-IC, and 24 best supportive care. At t-AML diagnosis, 42% and 44% of patients presented an unfavorable karyotype and unfavorable 2010 ELN risk profile, respectively. Among treated patients (n = 88), 43 (49%) achieved complete remission: four out of 33 (12%) and 39 out of 55 (71%) in non-IC and IC groups, respectively. With a median follow-up of 5.5 months, the median overall survival (OS) and disease-free survival (DFS) for the whole population were 9 months and 6.3 months, respectively, and for the 88 treated patients 13.5 months and 8.2 months, respectively. Univariate analysis on OS and DFS showed a significant impact of high white blood cells (WBC) and blast counts at diagnosis, unfavorable karyotype and ELN classification. Multivariate analysis showed a negative impact of WBC count at diagnosis and a positive impact of chemotherapy on OS and DFS in the whole population. It also showed a negative impact of previous auto-HCT and high WBC count on OS and DFS and of IC on OS in treated patients which disappeared when we considered only confounding variables (age, previous cancers, marrow blasts, and 2010 ELN classification). In a pair-matched analysis comparing IC treated t-AML with de novo AML, there was no difference of OS and DFS between the two populations. We showed, in this study that t-AML patients with unfavorable features represented almost half of the population. Best outcomes obtained in patients receiving IC must be balanced by known confounding variables and should be improved by using new innovative agents and therapeutic strategies.

Impact of insurance status and distance from residence to treatment center on the outcomes of patients diagnosed with acute myeloid leukemia

PurposeNumerous factors may affect the survival outcomes of patients with acute myeloid leukemia (AML), mainly disease-related and treatment-related factors. The impact of other factors, such as the insurance status and the distance to healthcare facilities, are still unclear and may differ between different healthcare systems. We investigated the effects of insurance status and distance to the treatment center on the survival of AML patients.Materials and methodsThis is a single-center, observational, retrospective study of patients diagnosed with AML (2015–2020) and treated at the American University of Beirut Medical Center in Lebanon. Data regarding patient baseline characteristics, disease-related factors, insurance status, and area of residence were collected. Multivariate Cox regression analysis was used to identify main independent predictors of overall survival (OS).ResultsWe identified 142 AML patients with a median age of 52 years (range 18–86). Of them, 91 (64%) were males, 77 (54%) had ELN intermediate risk, and 88 (62%) patients received intensive chemotherapy. After a median follow-up of 22.4 months, the median RFS and OS were 37.4 months and not reached, respectively. A Cox regression model for OS was done using the following variables: age, gender, body mass index, comorbidities, smoking status, insurance status, distance from the center, ELN classification, treatment used, and allotransplant. A higher risk of death was seen among the uninsured patients and those living beyond 40 km from the treatment center compared with fully insured patients and those living in proximity to the center (hazard ratio [HR]: 3.65; 95% CI [1.79, 7.45], p-value <0.0001; HR: 4.38; 95% CI [1.75, 10.95], p-value 0.002, respectively).ConclusionsThe outcome of patients with AML does not depend only on disease-related factors, as the insurance status and the distance from the area of residence to the treatment center were found to be independent predictors of survival in AML patients.

Presence of Measurable Residual Disease in NPM1 Positive AML in Remission Pre-Transplant Does Not Impact on Survival after Allogeneic Hematopoietic Stem Cell Transplantation

Due to their biological and clinical features, acute myeloid leukemia (AML) with Nucleophosmin-1 (NPM1) gene mutations represents a distinct entity within the WHO classification 2022. As per ELN classification, they are mainly categorized either as favorable or intermediate-risk disease, and as such patients are referred for allogeneic hematopoietic stem cell transplantation (allo-HSCT) at disease relapse, during CR1 or, less frequently, due to primary refractoriness. However, even when transplanted, relapse remains the most common cause of treatment failure. Besides conditioning intensity, presence of measurable residual disease (MRD) at time of allo-HSCT has recently been shown to be associated with an increased risk of relapse post-transplant. Yet, the reported effect might vary according to genetic and immunophenotypic diversity of the disease, transplant setting and MRD technology used. Here, we aim to determine the impact of NPM1 presence assessed via qPCR on post allo-HSCT outcomes. This retrospective study included adult AML patients harboring an NPM1 mutation (NPM1mut) who received a first allo-HSCT between January 2011 and January 2022 at four German transplant centers. NPM1 mutation status was assessed at diagnosis, and monitored throughout the treatment course by qPCR. NPM1 MRD monitoring was performed as previously described (Papadaki et al., 2009, sensitivity of 10−6). MRD status pre-transplant was correlated with outcome. There were no restrictions regarding donor type or conditioning intensity We identified 161 adult AML patients with available pre-transplant MRD status. Median age of the entire cohort was 55 years (21-75). The majority of patients (86%) had cytogenetically normal AML and presented in hematologic remission (CR1, CR2) (69%) at time of allo-HSCT. Whereas NPM1mut was measurable in all patients with active disease, 85/111 (77%) patients in remission had either NPM1mut persistence after antecedent induction/consolidation therapy (n=68) or molecular relapse (n=17). Conditioning intensity used was RIC in 57, MAC in 12, sequential-RIC in 88 and sequential-MAC in 4 patients. Most patients (n=90) were transplanted from matched unrelated donor (matched related: n=37, haploidentical: n=34), using preferentially PBSCs as graft source (n=146). At a median follow-up of 28 months (3-127), the estimated probability of OS and LFS at 2 years was 63% and 55%, respectively. When patients are stratified into groups with active disease, vs NPM1+CR vs NPM1- CR, 2-year OS and LFS show a significant difference (45% vs. 73% vs. 71%; p=0.002 and 55% vs. 62% vs. 67% p=0.005, respectively). Yet, if considering only patients in remission, no survival difference according to NPM1-MRD status at transplantation was detected (OS, p=0.49 and LFS, p=0.33). Likewise, cumulative incidence of relapse at 2 years was 44%, 15% and 17% (p=0.001); however among remission patients there was no significant difference between MRD+ and MRD- patients before allo-HSCT (p=0.96). CI of NRM at 1-year was 14%, 18% and 8% for non-CR, NPM1+ CR and NPM1- CR patients (p=0.9). Intriguingly, MRD positivity as assessed per qPCR at time of transplant did not impact on post-transplant outcome in our cohort of NPM1 positive AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal