Morphologic Leukemia-free State Research Articles

Early Bone Marrow Evaluation of Venetoclax Plus Hypomethylating Agents in Acute Myeloid Leukemia Patients

Introduction Venetoclax plus hypomethylating agents (VEN-HMAs) has been approved for the first-line treatment of acute myeloid leukemia (AML) and shown excellent efficacy. The standard duration of Venetoclax in VEN-HMAs is 28 days and the recommended bone marrow evaluation is approximately 21st to 28th day after stopping therapy. However, some patients developed severe myelosuppression during treatment and had to terminate the medication or reduce the dose. Some studies have indicated that shorter duration of venetoclax administration to 14 days has the same efficacy and better safety profile in treatment of AML. Therefore, we tried to investigate that early bone marrow evaluation on the 15th day of VEN-HMAs in the first cycle might evaluate bone marrow response earlier and make timely adjustments to the following regimens. In this study, we collected 52 patients who underwent bone marrow evaluation on the 15th day in the first VEN-HMAs cycle and observed the efficacy of early bone marrow evaluation. Method This study collected clinical data from 52 patients with AML who received the VEN-HMAs at the First Hospital of China Medical University from September 2019 to March 2024. The study was divided into newly diagnosed (ND) and relapsed/refractory (R/R) groups to evaluate basic information, ELN 2022 risk group classification, treatment response, duration of myelosuppression, the following regimens and survival outcomes. All the patients received 15th day of bone marrow. The primary endpoints were MLFS (Morphologic leukemia-free state) and complete remission (CR). The secondary endpoints were MRD (minimal residual disease), overall survival (OS) and relapse free survival (RFS). Statistical analyses were performed using SPSS 22.0 and R language 4.2.2. Survival curves were drawn with Kaplan-Meier and survival analysis between groups were performed using Log-rank test. P-values less than 0.05 were indicated statistical difference. Results A total of 52 patients completed the study, with 40 in the ND group and 12 in the R/R group. The median age of patients in the two groups were 66.0 years and 54.5 years. A total of 46 (88.5%) de novo AML and 6 (11.5%) secondary AML patients were included in this study. According to the 2022 ELN criteria, 11(21.2%), 15 (28.8%), and 26 (50.0%) patients were grouped to favorable, intermediate, and adverse risk groups, respectively. The total myelosuppression duration in two groups were 29.65 (±3.82) and 43.0 (±10.61) days. The data showed that 29 patients (72.5%) in ND AML patients obtained MLFS on the 15th day of VEN-HMAs in the first cycle. Among them, 19 patients received VEN for 14 days (VEN-14) due to severe myelosuppression or infection, and 10 patients continued VEN until 28 days (VEN-28). In the VEN-14 group, 63.2% (12/19) patients obtained CR MRD-, while 70% (7/10) patients in the VEN-28 group obtained CR MRD- (P=0.203). Based on the basic information containing age, sex, ELN risk stratification, bone marrow and peripheral blood count without statistical difference between the two groups, we compared the OS and RFS of VEN-14 group and VEN-28 group without statistical significance (OS: P=0.446, mOS had not been reached in both group; RFS: P=0.669, mRFS: 12m vs. 6m). Median follow-up time was 12 months. The myelosuppression duration in the VEN-14 and VEN-28 group were 33.5 (±6.12) and 23.5 (±3.76) days (P=0.271). Among the remaining 11 patients in ND group, 3 patients achieved partial response (PR) and 8 patients showed no response (NR) after 28 days of oral venetoclax without or with additional agents (3 cases, Cytarabine or Homoharringtonine) by re-evaluation of bone marrow. In the R/R group, 8 (66.7%) patients achieved MLFS in the early evaluation, including 2 with VEN-14 and 6 with VEN-28. 4 patients with NR or PR continued oral venetoclax to 28 days. The final CR MRD- rate was 41.6% (5/12) and CR/CRi (CR with incomplete hematologic recovery) rate was 75% (9/12). Conclusion Our real-world study indicated that early bone marrow evaluation is recommended in the AML target therapy, which can enhance clinical decision-making. For patients experiencing severe myelosuppression who have achieved MLFS, timely suspension of venetoclax is beneficial to the recovery of myelosuppression and doesn't affect short-term efficacy and long-term survival. Conversely, for patients with inadequate therapeutic efficacy, it allows for timely adjustments or changing treatment options.

Clinical efficacy and immune response of BCL-2 inhibitors combined with hypomethylating agents in the treatment of acute myeloid leukemia

ObjectiveAcute myeloid leukemia (AML) is a malignant clonal proliferative disease with a high mortality rate. The combination therapy of BCL-2 inhibitor Venetoclax (VEN) and hypomethylating agents (HMAs) has significant anti-leukemia activity.MethodsWe analyzed the efficacy, safety and immune response characteristics of AML patients who were unfit for high-dose chemotherapy and accepted the medication of VEN + HMAs.ResultsAfter VEN + HMAs treatment, 31 newly diagnosed AML patients had the morphologic leukemia-free state rate (MLFS%) of 80.6% (25/31), complete response rate (CR%) of 54.8% (17/31), the minimal residual disease negative rate (MRD-%) of 51.6% (16/31), and the median progression-free survival (PFS) of 14 months. After treatment, the proportion of bone marrow primitive cells, the MRD level, white blood cell (WBC) count, fibrinogen (FIB) level and the proportion of B cells were significantly decreased. The red blood cell (RBC) count, hemoglobin (HGB) level, platelet count (PLT) count, activated partial thromboplastin time (APTT), the proportion of total T cells, CD8 + T cells and the IFN-γ level were significantly increased. After VEN + HMAs treatment, 12 relapsed AML patients had a MLFS% of 50% (6/12), CR% of 33.3% (4/12), MRD-% of 25% (3/12), and a median PFS of 7 months. After treatment, the proportion of bone marrow primitive cells and MRD level were slightly decreased, the proportions of CD8 + T cells and NK cells were significantly increased, the proportion of B cells and IL-10 level were significantly decreased. 12 AML patients who receive microtransplantation (MST) treatment using VEN + HMAs as a pretreatment regimen had a PFS of 20.5 months, which was much greater than VEN + HMAs group alone. Hematological recovery was better in the MST group with significantly increased RBC count, HGB level and PLT count. The most common adverse events were myelosuppression, agranulocytosis, infection and cardiovascular toxicity. No fatal adverse events were reported.ConclusionThe combination of BCL-2 inhibitors and HMAs had good efficacy and safety in AML patients who were unfit for high-dose chemotherapy, which may improve the immune microenvironment and enhance anti-leukemia immune response.

Relationship between morphologic remission with or without hematologic recovery and outcome after allogeneic hematopoietic cell transplantation in adult acute myeloid leukemia.

Outcomes of adults with AML after allografting vary widely. While numerous covariates have been associated with relapse, non-relapse mortality (NRM), and/or shorter survival, the impact of incomplete blood count recovery before transplantation has remained unclear. To address this uncertainty, we examined all adults with AML or MDS/AML who received an allograft in first or second remission between 2006 and 2023 at a single institution. Of 1264 patients, 891 (70%) met criteria for CR, whereas 291 (23%), 24 (2%), and 58 (5%) were classified as CRh, CRi, and morphologic leukemia-free state (MLFS), respectively. CR, CRh, CRi, and MLFS patients differed significantly regarding demographics, disease biology, pre-transplant measurable residual disease, and types of transplants. After multivariable adjustment, outcomes for CRh and CRi patients were not significantly different from each other or from those of CR patients. In contrast, outcomes of MLFS patients were substantially worse than those of CR and CRh patients, with significantly higher risk of NRM and relapse, and significantly shorter relapse-free and overall survival. Similar results were obtained in several distinct subsets. Together, our analysis provides empiric evidence for the importance of distinguishing MLFS from CR and CRh patients for optimized risk assessment and, possibly, individualized treatment decision making.

Intensive chemotherapy after hypomethylating agent and venetoclax in adult acute myeloid leukemia

AbstractThe combination of a hypomethylating agent (HMA) and venetoclax (VEN) is approved for adults aged >75 years with newly diagnosed acute myeloid leukemia (AML) as well as those ineligible for intensive chemotherapy (IC). HMA/VEN is increasingly substituted for IC in adults with AML aged <75 years, particularly in those with adverse cytogenetic and molecular features. When patients fail to respond or relapse after HMA/VEN, the utility of salvage IC is largely unknown. We performed a retrospective single-institution study and identified 46 patients who received IC after HMA/VEN, including 24 patients who received HMA/VEN as their first treatment for AML. This population had complete remission (CR)/CR with incomplete count recovery (CRi)/morphologic leukemia-free state rate of 37%, CR/CRi rate of 28%, and a median overall survival (mOS) of 7.2 months (95% confidence interval, 5.0-10.3). Patients who relapsed after an initial response to HMA/VEN and subsequently received IC were more likely to achieve a CR/CRi than those refractory to HMA/VEN (50% vs 19%; P = .04), although there was no statistically significant difference in survival (mOS, 8.8 vs 5.4 months; P = .64). Age >65 years predicted poorer survival (mOS, 4.3 vs 10.6 months; P < .001). IC after HMA/VEN should be further studied and chosen with caution.

Predictive Models for Long Term Survival of AML Patients Treated with Venetoclax and Azacitidine or 7+3 Based on Post Treatment Events and Responses: Retrospective Cohort Study.

The treatment of acute myeloid leukemia (AML) in older or unfit patients typically involves a regimen of venetoclax plus azacitidine (ven/aza). Toxicity and treatment responses are highly variable following treatment initiation and clinical decision-making continually evolves in response to these as treatment progresses. To improve clinical decision support (CDS) following treatment initiation, predictive models based on evolving and dynamic toxicities, disease responses, and other features should be developed. This study aims to generate machine learning (ML)-based predictive models that incorporate individual predictors of overall survival (OS) for patients with AML, based on clinical events occurring after the initiation of ven/aza or 7+3 regimen. Data from 221 patients with AML, who received either the ven/aza (n=101 patients) or 7+3 regimen (n=120 patients) as their initial induction therapy, were retrospectively analyzed. We performed stratified univariate and multivariate analyses to quantify the association between toxicities, hospital events, and short-term disease responses and OS for the 7+3 and ven/aza subgroups separately. We compared the estimates of confounders to assess potential effect modifications by treatment. 17 ML-based predictive models were developed. The optimal predictive models were selected based on their predictability and discriminability using cross-validation. Uncertainty in the estimation was assessed through bootstrapping. The cumulative incidence of posttreatment toxicities varies between the ven/aza and 7+3 regimen. A variety of laboratory features and clinical events during the first 30 days were differentially associated with OS for the two treatments. An initial transfer to intensive care unit (ICU) worsened OS for 7+3 patients (aHR 1.18, 95% CI 1.10-1.28), while ICU readmission adversely affected OS for those on ven/aza (aHR 1.24, 95% CI 1.12-1.37). At the initial follow-up, achieving a morphologic leukemia free state (MLFS) did not affect OS for ven/aza (aHR 0.99, 95% CI 0.94-1.05), but worsened OS following 7+3 (aHR 1.16, 95% CI 1.01-1.31) compared to that of complete remission (CR). Having blasts over 5% at the initial follow-up negatively impacted OS for both 7+3 (P<.001) and ven/aza (P<.001) treated patients. A best response of CR and CR with incomplete recovery (CRi) was superior to MLFS and refractory disease after ven/aza (P<.001), whereas for 7+3, CR was superior to CRi, MLFS, and refractory disease (P<.001), indicating unequal outcomes. Treatment-specific predictive models, trained on 120 7+3 and 101 ven/aza patients using over 114 features, achieved survival AUCs over 0.70. Our findings indicate that toxicities, clinical events, and responses evolve differently in patients receiving ven/aza compared with that of 7+3 regimen. ML-based predictive models were shown to be a feasible strategy for CDS in both forms of AML treatment. If validated with larger and more diverse data sets, these findings could offer valuable insights for developing AML-CDS tools that leverage posttreatment clinical data.

A phase ib clinical trial of oral ciprofloxacin and etoposide in subjects with resistant acute myeloid leukemia

A phase 1b study was conducted to evaluate the safety and feasibility of ciprofloxacin and etoposide combination treatment in subjects with relapsed and refractory acute myeloid leukemia. Eleven subjects were enrolled in the study. Utilizing the standard ‘3 + 3’ design, escalating ciprofloxacin doses (750 mg, 1000 mg) twice daily on D1-D10 in combination with a fixed dose (200 mg) of etoposide on D2-D8 were administered. Maximum tolerated dose was determined to be 1000 mg of ciprofloxacin in combination with 200 mg of etoposide. Serious adverse events occurred in 54.5% (n = 6) subjects and 91% (n = 10) subjects reported ≥ grade 3 toxicities. Nine subjects completed treatment, one had a dose-limiting toxicity, and one withdrew. One subject achieved complete remission with a duration of 111 days and one subject achieved morphologic leukemia-free state after cycle 1. While the combination demonstrated safety and an acceptable toxicity profile, only modest hematologic and clinical benefits were observed. This trial was registered at www.clinicaltrials.gov as #NCT02773732.

Safety and efficacy of lisaftoclax, a novel BCL-2 inhibitor, in combination with azacitidine in patients with treatment-naïve or relapsed or refractory acute myeloid leukemia.

6541 Background: Investigational agent lisaftoclax (Lisa) was shown in preclinical findings to synergistically induce apoptosis in acute myeloid leukemia (AML). Here, we present follow up safety and efficacy data from a phase 1b/2 study evaluating Lisa + azacitidine (AZA) in adults with AML. Methods: Elderly (≥ 75 years)/unfit treatment-naïve (TN) and relapsed or refractory (R/R) AML (≥ 18 years) patients (pts) were enrolled. Lisa (400/600/800 mg) was administered orally once daily in 28-day cycles (a daily ramp up schedule was used for Lisa to prevent tumor lysis syndrome, TLS) combined with AZA (75 mg/m2/day on D1-7). Results: As of January 25, 2024, 76 AML pts were enrolled (R/R [n = 37]; elderly/unfit TN [n = 39]). The median (range) age was 66 (20-81) years and 61.8% of pts were male. All pts treated with Lisa + AZA reported TEAEs, with 89.5% Grade 3/4 AEs; and 43.4% SAEs. Common TEAEs (≥ 30%) included neutropenia (60.5%), thrombocytopenia (60.5%), diarrhea (42.1%), hypokalemia (40.8%), pyrexia (35.5%), and vomiting (30.3%). Grade ≥ 3 TEAEs reported in ≥ 10% of pts were neutropenia (57.9%), thrombocytopenia (50.0%), anemia (27.6%), pneumonia (17.1%), and febrile neutropenia (10.5%). No TLS was reported, and the 30-/60-day mortality rates were 1.3% and 3.9%, respectively. In pts with R/R AML treated with Lisa + AZA, the overall response ([ORR] = CR + CRi + morphologic leukemia-free state [MLFS] + PR) and composite complete remission (CRc = CR + CRi) rates were 72.7% and 45.5%, respectively. In the 600 mg cohort (n = 30), ORR and CRc were 76.7% and 50.0%; the median (range) duration of treatment (mDoT), 3.8 (0.8‒15.4) month (mo); median time to CRc (mTTCRc), 2.5 (95% CI, 1.5-6.1) mo; median PFS was 10.2 (95% CI, 6.5-NR) mo; and median OS was 14.7 (95% CI, 7.8-NR) mo. Among 39 pts with TN AML treated with Lisa + AZA, ORR and CRc were 64.1% and 51.3%, respectively (Table). In the 600 mg cohort (n = 29), mDoT was 3.3 (1.0- 9.9) mo; mTTCRc was 1.9 (95% CI, 1.2-3.3) mo; median PFS was not reached (3.5, NR). 600 mg of Lisa + AZA was established as the recommended phase 2 dose. Conclusions: Our data support an emerging role for this new BCL-2 inhibitor Lisa combined with AZA for the treatment of elderly/unfit TN and R/R AML pts, especially with low early mortality and promising mPFS. A phase 3, randomized, double-blind clinical study is in progress to determine whether Lisa + AZA improves OS in elderly/unfit pts with AML. *HW, XW, and YL are co-first authors. Clinical trial information: NCT04501120 . [Table: see text]

Overexposure to venetoclax is associated with prolonged-duration of neutropenia during venetoclax and azacitidine therapy in Japanese patients with acute myeloid leukemia.

An observational study was conducted to evaluate the pharmacokinetics of venetoclax and its impact on the efficacy and safety for Japanese patients with acute myeloid leukemia (AML) treated with venetoclax and azacitidine therapy. The association between the plasma concentration, after the first cycle of azacitidine and venetoclax therapy, and the efficacy and safety was evaluated in 33 patients with untreated or relapsed/refractory AML. Full dose of venetoclax was administered to all patients. Venetoclax treatment was 28day long in 82% of patients; the relative dose intensity of azacitidine was 82%. Trough concentration was significantly higher among patients with complete remission (CR) and CR with incomplete hematologic recovery (CRi) than those with the morphologic leukemia-free state and partial remission, and no response groups (P = 0.01). Median duration of grade 3 neutropenia was 28 days (range 8-46 days). Area under the concentration-time curve (AUC0-24) was significantly higher among patients with protracted grade 3 neutropenia (≥ 28 days) than those with a shorter duration (< 28 days) (P = 0.03); multivariate analysis revealed that a higher AUC0-24 was a significant predictor of a longer duration of neutropenia (odds ratio 54.3, P = 0.007). Plasma concentrations of venetoclax were variable in Japanese patients with AML. Higher plasma concentrations were associated with CR/CRi and protracted grade 3 neutropenia. Therefore, it is essential to adjust the duration of venetoclax administration based on individual pharmacokinetic data to limit total drug exposure, reduce severe neutropenia, and achieve higher efficacy.

Safety and tolerability of AMG 330 in adults with relapsed/refractory AML: a phase 1a dose-escalation study

AMG 330, a bispecific T-cell engager (BiTE®) that binds CD33 and CD3 on T cells facilitates T-cell–mediated cytotoxicity against CD33+ cells. This first-in-human, open-label, dose-escalation study evaluated the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of AMG 330 in adults with relapsed/refractory acute myeloid leukemia (R/R AML). Amongst 77 patients treated with AMG 330 (0.5 µg/day–1.6 mg/day) on 14-day or 28-day cycles, maximum tolerated dose was not reached; median duration of treatment was 29 days. The most frequent treatment-related adverse events were cytokine release syndrome (CRS; 78%) and rash (30%); 10% of patients experienced grade 3/4 CRS. CRS was mitigated with stepwise dosing of AMG 330, prophylactic dexamethasone, and early treatment with tocilizumab. Among 60 evaluable patients, eight achieved complete remission or morphologic leukemia-free state; of the 52 non-responders, 37% had ≥50% reduction in AML bone marrow blasts. AMG 330 is a promising CD33-targeted therapeutic strategy for R/R AML.

Azacitidine, Venetoclax, and Gilteritinib in Newly Diagnosed and Relapsed or Refractory FLT3-Mutated AML.

Azacitidine plus venetoclax is a standard of care for patients with newly diagnosed AML who are unfit for intensive chemotherapy. However, FLT3 mutations are a common mechanism of resistance to this regimen. The addition of gilteritinib, an oral FLT3 inhibitor, to azacitidine and venetoclax may improve outcomes in patients with FLT3-mutated AML. This phase I/II study evaluated azacitidine, venetoclax, and gilteritinib in two cohorts: patients with (1) newly diagnosed FLT3-mutated AML who were unfit for intensive chemotherapy or (2) relapsed/refractory FLT3-mutated AML (ClinicalTrials.gov identifier: NCT04140487). The primary end points were the maximum tolerated dose of gilteritinib (phase I) and the combined complete remission (CR)/CR with incomplete hematologic recovery (CRi) rate (phase II). Fifty-two patients were enrolled (frontline [n = 30]; relapsed/refractory [n = 22]). The recommended phase II dose was gilteritinib 80 mg once daily in combination with azacitidine and venetoclax. In the frontline cohort, the median age was 71 years and 73% of patients had an FLT3-internal tandem duplication (ITD) mutation. The CR/CRi rate was 96% (CR, 90%; CRi, 6%). Sixty-five percent of evaluable patients achieved FLT3-ITD measurable residual disease <5 × 10-5 within four cycles. With a median follow-up of 19.3 months, the median relapse-free survival (RFS) and overall survival (OS) have not been reached and the 18-month RFS and OS rates are 71% and 72%, respectively. In the relapsed/refractory cohort, the CR/CRi rate was 27%; nine additional patients (41%) achieved a morphologic leukemia-free state. The most common grade 3 or higher nonhematologic adverse events were infection (62%) and febrile neutropenia (38%), which were more frequent in the relapsed/refractory cohort. The combination of azacitidine, venetoclax, and gilteritinib resulted in high rates of CR/CRi, deep FLT3 molecular responses, and encouraging survival in newly diagnosed FLT3-mutated AML. Myelosuppression was manageable with mitigative dosing strategies.

Alrizomadlin (APG-115) Alone or Combined with Azacitidine (AZA) in Patients (pts) with Relapsed or Refractory (R/R) Acute Myeloid Leukemia (AML) or Relapsed or Progressive Higher-Risk Myelodysplastic Syndrome (HR-MDS): Phase 1b Trial Results

*Drs. Yifan Zhai and Jianxiang Wang are co-corresponding authors. Background Pts with R/R AML and HR-MDS failing hypomethylating agents have limited therapeutic options and relatively dismal outcomes with available therapies. Investigational alrizomadlin is a novel, orally active, potent, small-molecule selective inhibitor that destabilizes the p53-MDM2 complex and activates p53-mediated apoptosis in tumor cells and has shown apoptotic activity in AML and MDS xenograft models, alone and combined with AZA. Here, we present safety and efficacy results of this therapy in these pts. Methods This open-label dose escalation and expansion trial included adults with R/R AML or relapsed/progressed HR-MDS (IPSS-R ≥ 4.5). MTD and RP2D of alrizomadlin ± AZA were determined by dose escalation. Alrizomadlin (100/150/200/250 mg) was administered orally on Days (D) 1-7 in 28-day cycles. In the combination dose escalation group, alrizomadlin (100/150/200 mg) + AZA (75 mg/m 2) was administered orally once daily on D 1-7 in 28-day cycles and at the combination RP2D during dose expansion. Responses were assessed per revised International Working Group (IWG) Response Criteria 2003, ELN 2017 classifications for AML, and IWG 2006 for MDS. Extensive pharmacokinetic (PK) analyses were performed. Results As of June 1, 2023, 29 pts were enrolled in China. In the monotherapy group, 21 pts (median [range] age, 65 [32-76] years; 76.2%, R/R AML) had a median (range) of 2 (1-10) prior lines of therapy. In the combination group, 8 pts (median [range] age of 69.5 [20-76] years; 50%, R/R AML) had a median (range) of 2 (1-4) prior lines of therapy. In both groups, common any-grade treatment-related adverse events (TRAEs; ≥ 20%) were hematologic- and gastrointestinal-related toxicities, hypokalemia, and dizziness, and most grade ≥ 3 TRAEs were hematologic toxicities. No grade ≥ 3 gastrointestinal toxicities were reported (Figure 1). One DLT, a pulmonary embolism (PE), was reported among 6 evaluable patients at the alrizomadlin 100 mg + AZA dose level: a 59-year-old pt with MDS had a prior COVID-19 infection and abnormal coagulation function before (and during) study treatment. The study investigator attributed the PE to the pt's COVID-19 infection, age, primary disease, and long-term bed rest. One pt in each arm discontinued treatment because of AEs. In pts with AML, the overall response rate (ORR) was defined as complete remission (CR) + CR with incomplete hematologic recovery (CRi) + partial response (PR) + morphologic leukemia-free state (MLFS). In pts with MDS, ORR was defined as CR + PR + marrow CR (mCR). In the monotherapy group, the ORR and CR/CRi rates among pts with R/R AML were 25% (4/16) and 18.75% (3/16), respectively. Three of 6 pts with MDS that progressed to R/R AML experienced responses, including 2 CRis and 1 MLFS. One of 10 pts with R/R AML treated with venetoclax + HMA experienced a CRi. In the monotherapy cohort, 4 pts with MDS refractory to HMAs were evaluated, of whom 2 experienced an mCR. The monotherapy RP2D was determined as 200 mg. In the combination group, 6 pts had an efficacy evaluation at least once. Among these pts, 3 of 3 with MDS experienced an mCR and 1 of 3 with R/R AML, MLFS. Among 4 pts with prior venetoclax + HMA treatment, 2 with MDS experienced an mCR and 2 with R/R AML showed a half marrow blast reduction at the end of C1 (Table 1). No PK drug-drug interaction between alrizomadlin and AZA was observed. Conclusions Alrizomadlin alone or combined with AZA demonstrated a manageable safety profile and preliminary efficacy in pts with R/R AML and HMA-refractory MDS. An antileukemic effect was observed in both monotherapy and combination settings, including a few pts whose disease failed on prior venetoclax treatment. Evaluation of the alrizomadlin + AZA cohort is ongoing. Internal study (CT.gov) identifiers: APG-115-AC101 (NCT04275518).

MYC Pathway Upregulation Identified in Non-Responders to Hypomethylating Agents and Presents a Therapeutic Target in Acute Myeloid Leukemia

Background: In the current era of acute myeloid leukemia (AML) management, hypomethylating agents (HMAs) remain as the backbone of combination regimens for front-line treatment of elderly or unfit patients (pts) and/or as salvage therapy in relapsed/refractory pts. Data on biological predictors of HMA response are limited. Our previous work explored cytidine deaminase (CDA), known to inactivate HMAs, and nucleophosmin 1 (NPM1), determined by core pathway analysis to indirectly influence CDA expression. No clear correlation was identified in pt samples between CDA protein expression and NPM1 status or response, and pharmacogenomic analysis showed no CDA single nucleotide polymorphisms were predictive of response to HMAs. We aimed to expand prior findings using RNA sequencing (RNA seq) and gene set enrichment analysis (GSEA) to identify gene signatures predictive of HMA response and propose potential therapeutic targets. Methods: AML pts with banked samples who received frontline, bridging, or salvage HMA-based therapy between January 2014 to December 2018 were reviewed. Responses following at least 2 cycles of HMA were categorized as complete response (CR), CRi (CR with incomplete hematologic recovery), morphologic leukemia-free state (MLFS), complete hematologic response (CHR), or refractory. Pts were categorized as responders (CR, CRi, MLFS, CHR) or non-responders (refractory). Tumor cells were purified using immunomagnetic selection from bone marrow aspirates collected at diagnosis (dx). RNA seq was performed on 20 available pt tumor samples. Unsupervised clustering was performed and GSEA was completed to compare identified clusters using a false discovery rate (FDR) cut-off of less than 25%. GSEA-derived gene pathway scores were assessed by Wilcoxon rank-sum test. To evaluate AML cell lines to explore the non-responder phenotype, viability of AML cell lines was assessed following treatment with HMA azacitidine (Aza) and MS177 (a proteolysis targeting chimeric EZH2 degrader, also known to degrade MYC). Immunoblotting was used to assay proteolysis targeting chimeric (PROTAC)-induced MYC degradation. Results: Unsupervised clustering of RNA seq from 20 tumor samples at dx, labeled for response and NPM1 status, revealed 3 distinct groups: a non-responder group, a responder group, and a mixed response group ( Figure 1A). GSEA comparing the non-responder group to the responder group revealed several enriched genes in the non-responder group, including MYC targets (FDR &amp;lt;0.001), E2F targets (FDR &amp;lt;0.001), and G2M checkpoint (FDR=0.244). Upregulation of MYC targets was confirmed by enrichment profiling. Application of enrichment pathway scores revealed significant differences between non-responders and responders for E2F targets (p=0.026), G2M checkpoint (p=0.026), and MYC targets (p=0.0022). To explore MYC as a therapeutic target, we assayed MYC degradation in leukemia cells treated with two PROTAC degraders. The PROTAC MS177 induced marked MYC degradation in HL-60 cells ( Figure 1B). Cytotoxicity assays showed that in Kasumi-1 cells, the 50% inhibitory concentrations (IC50) for Aza and MS177 were 2.9 µM (responder phenotype) and 1.1 µM, respectively ( Figure 1C); in HL-60 cells the IC50 for Aza and MS177 were 10.9 µM (non-responder phenotype) and 0.06 µM, respectively ( Figure 1D). MS177 also showed efficacy in cytotoxicity assays using pt derived tumor samples. Conclusions: Using tumor samples from AML pts receiving HMAs, we identified a non-responder gene phenotype enriched with MYC upregulation. GSEA-derived pathway scoring differentiated non-responders from responders in our dataset. To further evaluate whether the enrichment pathway score is predictive for response across other AML cohorts, we are applying enrichment scores to publicly available AML datasets. With MYC upregulation identified as a potential driver of HMA failure, MYC degradation or inhibitory targets are recognized as potential therapeutic targets for pts with a non-responder gene signature. We established the HL-60 AML cell line, found to be less sensitive to Aza than the Kasumi-1 cell line, demonstrated greater sensitivity to MYC degradation compared to Kasumi-1 cells and may reflect the non-responder phenotype. Further in vitro efforts are ongoing to evaluate MYC targets for the HMA non-responder phenotype.

Fludarabine, Cytarabine (ARA-C) and Pegylated Erwinase (PEGCRISANTASPASE) in Patients with Relapsed or Refractory Leukemia

Background: Asparaginase, which depletes serum asparagine by breaking it down into asparagine, is part of the standard of care along with chemotherapy, in adolescent and young adult patients with acute lymphoblastic leukemia (ALL). Leukemic blasts require asparagine for survival, therefore serving as an important therapeutic target; among the mechanisms of resistance includes the upregulation of expression of asparagine synthetase (AS) (gene located in chromosome 7). Depletion of asparagine and more recently glutamine may also have an important role in the treatment of acute myelogenous leukemia, either alone or in combination with chemotherapy. Pegcristaspase (PegC) is a long-acting pegylated asparaginase derived from Erwinia that also has a glutaminase activity. We hypothesize that the combination of chemotherapy and PegC might overcome resistance and provide therapeutic benefit pts with relapsed and/or refractory leukemias. Methods: This is a phase Ib study of fludarabine, cytarabine (ara-c), and PegC in patients with relapsed or refractory leukemia (NCT 04526795). Pts received induction cycle (C) (defined as 5 weeks) with PegC on day (D) 1 and 15 as single agent. Fludarabine (30mg/m 2/D) and 4 hours later Cytarabine (1.5g/m 2/D) are given D 8 to D 11. A 3+3 dose-escalation approach was implemented to evaluate 3 different dose levels for pegcrisantaspase (level -2: 350 IU/m 2; level -1: 500 IU/m 2; and level 1: 750UI/m 2). Once the MTD is established, an expansion cohort to further evaluate safety and efficacy was opened. Endpoints included safety, overall response rate (complete remission [CR], CR with incomplete count recovery [CRi], partial remission [PR], or morphologic leukemia free state [MLFS] ) of fludarabine, araC, and pegcrisantaspase in patients with relapsed and refractory leukemias. Response was denoted as per the ELN 2017 criteria. Results: From April 2021, 15 pts have been treated on the trial, 12 (80%) pts with AML, 2 pts (13%) with ALL (one patient was Ph+ ALL), and 1 patient with isolated myeloid sarcoma. The median age was 46 years (range, 22-61), median bone marrow blasts were 37% (1-90) . 9/15 (60%) patients had complex karyotype. Patient characteristics are summarized in Table 1. The median lines of prior therapy was 4 (range, 1-9). Six pts were treated at dose level -1 and then at dose level 1. There were no dose limiting toxicities to proceed to the expansion cohort. From the 15 treated pts, 2 patients from the dose level -1 died from sepsis related to disease progression within the first 4 weeks. Overall, 3 pts (20%) responded to treatment (2CRp and 1 CRi). The patient with Ph+ B-ALL achieved CRp, proceeded to SCT, and remains alive in remission. The 2 other patients (both with AML) relapsed after 6 weeks and 4 months, respectively. The median overall survival was 2.6 months. (Figure 1) A total of 29 adverse events (AE) were noted in 13/15 patients. The most common AEs was grade ≥ grade 3 neutropenic fever (10 pts, 67%; including 2 grade 5 events). The only possibly related AE was tumor lysis syndrome in one patient, grade 3, and was successfully managed per institutional guidelines. Conclusion: In this high-risk, heavily treated population, the combination of fludarabine, cytarabine, and PegC is feasible. Responding patients included 2 AML and 1 ALL. Further exploratory analysis about the relation between response and asparagine depletion as well as specific sensitive subsets could clarify which patients might benefit the most from this combination.

Real World Use of Azacitidine and Venetoclax in Acute Myeloid Leukemia in Frontline and Relapse/Refractory Settings: A Multicentric Study from French Auraml Group

Azacytidine and venetoclax combination regimen (AZA/VEN) is the standard of care in frontline acute myeloid leukemia (AML) settings for unfit to intensive chemotherapy patients. However, AZA/VEN is also associated with an increased hematological toxicity compared to azacytidine alone. In this context, alternative AZA/VEN regimens emerged progressively based on each physician experience and local procedures. Moreover, AZA/VEN is also recognized as a valuable therapeutic option in relapse/refractory settings. In this multicentric study, we aimed to evaluate the efficacy and safety of various AZA/VEN regimen in frontline and relapse/refractory (R/R) patients diagnosed with AML in real life setting. We retrospectively analyzed 331 patients from 11 different French centers (Saint-Etienne, Clermont-Ferrand, Lyon (Hopital Lyon Sud, Centre Léon Bérard), Vichy, Annecy, Chambery, Valence, Bourgoin-Jallieu, Grenoble, Roanne) in Auvergne Rhône Alpes (AURA) region, between January 2019 and February 2023. Composite complete remission was defined as in VIALE-A trial. Measurable residual disease (MRD) negativity was defined as ≤ 10 -3 by flow cytometry (on bone marrow) and/or ≤ 10 -4 for NPM1 by RT-qPCR. Overall, the entire cohort was composed of 186 and 146 patients in frontline and R/R settings respectively. In frontline setting, median age was 74.5 (19.1-86.1) and ELN 2022 risk groups were favorable, intermediate and unfavorable in 14.5, 16.7 and 68.8% respectively. De novo AML, MRC-AML, post-MPN/MDS AML and t-AML were 32.4%, 29.7%, 23.2% and 14.5% respectively. After 6 cycles, median CRc, morphologic leukemia free state (MLFS) and refractory rate were 66.4%, 5.4% and 28.2% respectively. Regarding probability of CRc, there was no significant difference between favorable and intermediate ELN 2022 risk group. Within unfavorable risk group, only complex karyotype was associated with lower CRc rate ( figure 1). Venetoclax dosage (400mg vs 100mg/d) and duration per cycle (28 days vs 21 days vs others) did not influence significantly CRc rate probability and OS. With a median follow-up of 7.3 months, median overall survival (OS) was 12.4 months (IC95%: 3.4-18.5). There was no significant difference in terms of OS according to ELN 2022 risk group classification ( figure 2). Among unfavorable risk group, only patients with unfavorable karyotype had a worst OS (median OS: 4.9 months), while patients with secondary AML mutations had similar OS than favorable/intermediate risk group (19.5 vs 20.2 vs 18.2 months, p=0.32). Reaching MRD negativity at any time during the first 6 cycles was associated with a better OS (26.1 vs 10.3 months, p&amp;lt;0.001). In responding patients, 22/122 withdrew VEN after a median of 5 cycles (range:1-17), while continuing AZA, mainly due to excessive hematological toxicity. Relapse free survival was similar between patients who stopped compared to those who continued up to progression. In multivariate analysis, only ECOG (continuous, HR= 1.52, p=0.04), IDH status (WT vs MUT: HR = 3.13, p=0.04, normal karyotype (yes vs no, HR=0.25, p=0.04) and CR type (CRMRD- vs other, HR= 0.21, p=0.001) significantly influence OS, whereas ELN 2022 did not In R/R settings, CRc rate was 43.8% and OS was 7.9 months. As in frontline setting, venetoclax dosage and duration per cycle did not influence CRs rate and OS. Febrile neutropenia (FN) occurred in 52.9%, 35.1% and 27.1% in cycle 1,2 and 3, respectively. Toxic death rates (TDR) range from 16.6% prior 2020 to 8.6% in 2021 and 6.25% from 2022 to 2023 (p=0.01). In or outpatient management for cycle 1 did not influence FN incidence. Azole prophylaxis did not significantly influence FN incidence. During cycle 1, shorter venetoclax duration regimens (&amp;lt;21 days/cycle) was associated with lower FN (41.5 vs 54.8%, p=0.042) compared to ≥21 days VEN cycle. In this real life settings study, our results suggest that outcome in frontline AZA/VEN treated patients is mainly driven by deep responses. Alternative AZA/VEN regimens were not associated with lower response rate and overall survival, while reducing venetoclax exposure during cycle 1 may reduce FN incidence without significant consequences on CR rate. TDR reduction through time suggest a learning curve and might be related to physician's skills improvement regarding AZA/VEN dosage schedules and supportive care management. An update with additional patients and longer follow-up will be presented at the meeting.

Final Results of the Phase Ib/II Study Evaluating Enasidenib in Combination with Venetoclax in Patients with IDH2-Mutated Relapsed/Refractory Myeloid Malignancies

BACKGROUND: Theisocitrate dehydrogenase 2 ( IDH2) gene is mutated in ∼10-15% cases of acute myeloid leukemia (AML) and ∼5% cases of myelodysplastic syndromes (MDS). Enasidenib (ENA) is an oral selective IDH2 inhibitor used for treatment of IDH2-mutated (m IDH2) relapsed/refractory (R/R) AML. Preclinical studies showed that m IDH2 AML cells are particularly sensitive to BCL2 inhibition with venetoclax (VEN) and combination of ENA and VEN is more effective than single agents in patient-derived xenograft models of m IDH2 AML. Based on this rationale, we conducted a phase Ib/II trial evaluating the safety and efficacy of ENA plus VEN in patients (pts) with m IDH2 R/R AML or MDS (NCT04092179). METHODS: This single-arm phase Ib/II trial was conducted at the Princess Margaret Cancer Centre and the University of Alberta Hospital in Canada. Pts ≥ 18 years with m IDH2 R/R AML or MDS, adequate organ function and ECOG performance status ≤ 2 were eligible. Participants were not eligible if they had prior exposure to IDH2 or BCL2 inhibitors. Pts were treated continuously by 28-day cycles of VEN 400 mg daily starting with a 3-day ramp-up on cycle 1 day 1 and with ENA 100 mg daily starting on cycle 1 day 15. The primary endpoints were safety, tolerability and recommended phase 2 dose (RP2D) for the phase Ib part and overall response rate (ORR) for the phase II part. ORR included complete remission (CR), CR with partial hematological recovery (CRh), CR with incomplete hematological recovery (CRi), morphologic leukemia-free state (MLFS) and partial remission (PR) as defined by the European Leukemia Network (ELN). Duration of response (DOR), overall survival (OS), pharmacokinetic (PK) analysis for VEN and bone marrow (BM) IDH2 variant allele frequency (VAF) by droplet digital PCR (ddPCR) were also evaluated. RESULTS: From November 2020 to July 2022, 27 pts were enrolled: 12 in the phase Ib and 15 in the phase II. Almost all pts had AML, except one with MDS who progressed on treatment with azacitidine. The data cutoff date was June 30, 2023. The median age was 70 years (range, 23 - 84) ( Table 1). Patients had a median of 1 prior line of treatment (range, 1-2) including 5 (19%) who had previously undergone allogeneic stem cell transplant (HSCT). Fifteen (56%) and 12 (44%) pts had R140Q and R172K/W IDH2 mutation (mut), respectively. The median BM IDH2 VAF at baseline was 23.4 (range 2.3 - 49.9). The most common (≥ 20%) grade 3-5 treatment emergent adverse events (TEAEs), regardless of attribution, were febrile neutropenia (41%), lung infection (22%) and thrombocytopenia (26%). Nausea, vomiting and diarrhea occurred each in 41% of pts, but were primarily grade 1-2 (only 1 pt with grade 3 diarrhea). Hyperbilirubinemia of any grade occurred in 48% pts, including grade 3 in 15%. No case of IDH inhibitor associated differentiation syndrome (IDH-DS) occurred in this study. Grade 3 leukocytosis without IDH-DS occurred in 2 (8%) pts. No patient discontinued ENA because of an adverse event and no treatment-related death was reported. The PK profile of VEN was not altered by ENA, and the RP2D was VEN 400 mg daily plus ENA 100 mg daily. Among 23 pts with R/R AML evaluable for response, the ORR was 70% (16/23), including 57% (13/23) CR ( Figure 1). In pts with R172 mut, the ORR and CR rates were 83% (10/12) and 67% (8/12), respectively, versus 55% (6/11) and 45% (5/11) in pts with R140 mut. m IDH2 VAF at baseline was similar between responders and non-responders. On follow-up BM samples, there was an association between response and decrease in m IDH2 VAF. Clearance of m IDH2 was observed in 47% (7/15) of analyzed responders. The median time to initial response was 1 month (range, 0.9 - 5.7), and the median time to best response was 2.8 months (range, 0.9 - 12.5). The median DOR was 16.6 months (95% CI 5.0 - NR) and pts received a median of 7 cycles of treatment (range, 1 - 32). With a median follow-up of 17.1 months (range, 0.9 - 31.4), 10 (38%) pts were alive, including 9 (35%) in ongoing remission. The median OS was 9.4 months (95% CI, 8.2 - NR) and the 2-year OS rate was 42% (95% CI, 27 - 66). Four pts proceeded to HSCT after achieving remission, of whom 2/4 (50%) are alive in remission on last follow-up. CONCLUSIONS: The combination of ENA and VEN is safe and well tolerated in pts with R/R m IDH2 myeloid malignancies. The ENA-VEN combination compares favorably to ENA single-agent in this patient population. Further studies of targeted combination therapies using IDH2 and BCL2 inhibitors are warranted.

Outcomes of Patients with Accelerated/Blast-Phase MPNs That Received Allogeneic Stem-Cell Transplant in the Current Era of Myeloid Therapies

Background Patients (pts) with Philadelphia chromosome-negative (Ph-neg) myeloproliferative neoplasms (MPNs) that progress to an accelerated phase (AP) or blast phase (BP) have a median overall survival (mOS) of less than 1 year (Odenike, Blood 2018; Tam et al, JCO 2009). Allogeneic hematopoietic stem cell transplant (allo-HCT) is the only curative approach for MPN-AP/BP, but mOS remains about a year for pts with MPN-BP that undergo allo-HCT (2005-2019) (Orti et al, AJH 2023). We previously reported on outcomes of pts with MPN-AP/BP treated in the current era of myeloid therapies (2017 onward) and found a mOS of 0.73 years in a multi-center cohort of 80 pts (Patel et al, ASH 2022). We aim to characterize treatment patterns and outcomes of pts with MPN-AP/BP that underwent allo-HCT via a multi-center retrospective analysis. Methods Retrospective chart review was performed at 8 institutions to identify pts with pathology-confirmed Ph-neg MPN-AP/BP diagnosed in 2017 or later. All patients that met inclusion criteria were included. Response was assessed using 2017 European Leukemia Net AML (2017 ELN) criteria (Dohner et al, Blood 2017). OS from diagnosis of MPN-AP/BP and from time of allo-HCT was calculated utilizing Kaplan-Meier analysis. Results The full MPN-AP/BP cohort consists of 180 pts. This analysis includes 58 pts that underwent allo-HCT for MPN-AP/BP across 8 institutions. Median age at MPN-AP/BP diagnosiswas 64 years. The most common therapies for chronic-phase MPN included hydroxyurea (55%), JAK inhibitor (JAKi) (26%), interferon (9%), and hypomethylating agent (HMA, 4%). No patient previously received allo-HCT for chronic-phase MPN. Driver mutations included JAK2 (60%), CALR (22%), MPL (10%), but some pts had triple-negative disease (7%). Sixty-two percent of pts had high-risk disease by 2017 ELN criteria. Forty-four pts had next-generation sequencing performed at time of MPN-AP/BP diagnosis. The most frequently co-occurring mutations detected at time of MPN-AP/BP diagnosis were ASXL1 (30%), SRSF2 (23%), RUNX1 (23%), TP53 (18%), TET2 (16%), IDH2 (11%), U2AF1 (7%), EZH2 (7%), and IDH1 (9%). Additional characteristics are in Table 1. One pt proceeded directly to allo-HCT at time of MPN-AP/BP diagnosis. Frontline therapies (1L) for MPN-AP included intensive chemotherapy (IC) (n=26), hypomethylating agent (HMA) + venetoclax (VEN) (n=16), HMA monotherapy (n=14), and low-dose cytarabine (LDAC) + VEN + JAKi (n=1). Responses are summarized in Table 2A. Thirty-seven pts proceeded to allo-HCT after 1L therapy (17 after IC, 10 after HMA+VEN, 9 after HMA, 1 after LDAC+VEN+JAKi). Twenty pts proceeded to allo-HCT after 2 nd-line and beyond (2L+) therapies. Therapies utilized and responses are summarized in Table 2B. Transplant-specific characteristics include 15 pts receiving myeloablative conditioning while 43 received reduced-intensity conditioning. Donor source was matched unrelated donor for 33 pts, haploidentical donor for 10 pts, matched related donor for 9 patients, mismatched unrelated donor for 5 patients, and cord blood for 1 patient. Twenty-two pts developed acute GVHD while 15 developed chronic GVHD. Amongst the 58 pts that underwent allo-HCT, 19 had relapse of disease and 8 patients received treatment after relapse. Amongst the full cohort of 180 patients, mOS was 0.72 years from time of MPN-AP/BP diagnosis. The mOS for the 58 pts that underwent allo-HCT was 1.82 years from time of MPN-AP/BP diagnosis and 1.30 years from time of allo-HCT. Survival analysis by initial MPN-AP/BP therapy demonstrated a mOS from time of MPN-AP/BP diagnosis of 1.9 years for HMA-based therapy, 1.9 years for HMA + VEN, and 1.5 years for IC ( p=0.006). We also analyzed mOS by disease status prior to transplant. Thirty-four pts had a complete response (CR) or CR with incomplete count recovery (CRi) with mOS of 1.7 years from time of allo-HCT, 12 pts with a partial response (PR) or morphologic leukemia-free state (MLFS) had mOS of 1.8 years, and 11 pts with treatment failure (TF) had mOS of 0.47 years (p=0.82). Conclusions Our cohort of 180 pts with MPN-AP/BP treated in the current era of myeloid therapies had limited survival with a mOS of 0.72 years from MPN-AP/BP diagnosis. Amongst the 58 pts that underwent allo-HCT the mOS was 1.82 years with longer mOS seen in pts that received HMA or HMA + VEN as their 1L therapy when compared to IC. This underscores the need for novel management strategies even in pts eligible for allo-HCT.

Clinical Features and Treatment in Patients Diagnosed with Blastic Plasmacytoid Dendritic Cell Neoplasm: Interim Analysis from the Pethema Epidemiologic Registry (EPI-BLAS study)

Background BPDCN (Blastic Plasmacytoid Dendritic Cell Neoplasm) is a rare and aggressive hematological neoplasm, and due to its rarity there are scarce registry studies analyzing the disease in real-world. The proposed study seeks to fill this knowledge gap and gain insights into various aspects of the disease, including demographics, presentation features, biological data, treatment patterns, and individual patient outcomes. Ultimately, the study aims to shed light on how to best manage BPDCN and identify patients who could benefit from curative treatments, including front-line agents followed by allogeneic stem cell transplant (allo-HSCT) and novel therapies, like IL3R-diphteric toxin compound (SL-140; Tagraxofusp) which showed remarkable activity in front-line therapy. Methods The EPI-BLAS is a retrospective, multicenter, non-interventional chart review study of patients diagnosed with BPDCN. Approximately 150 patients treated at PETHEMA participating sites in Spain will be included in final analyses. The review will focus on medical records of patients diagnosed with BPDCN, and the data will be entered into an electronic case report form (eCRF) for all patients who meet the inclusion and exclusion criteria. For this analysis, we included a first cohort of 68 adult patients (≥18 years old) who were diagnosed BPDCN between January 2010 and January 2022. Results The median age at diagnosis was 66 years (range 18-87 years). The majority of the patients (74%) was de novo, while 26% of them had a prior history of neoplastic disease [43% of them had prior solid neoplasm (thyroid cancer, prostate adenocarcinoma, melanoma and breast ductal carcinoma) and 57% suffered from hematological neoplasms as large granular lymphocytic leukemia, myelodysplastic syndromes, non-Hodgkin T-cell lymphoma and chronic myelomonocytic leukemia]. Previous anti-cancer therapy was received by 36 patients. Table 1 shows main baseline characteristics of BPDCN patients. Regarding first-line treatment, 34 patients (50%) received AML-like regimens [19 underwent anthracycline and cytarabine (3+7 regimen), 4 FLAGIDA, 4 received FLUGA (fludarabine plus low-dose cytarabine), 1 cytarabine alone, and 1 azacitidine alone]; 9 (13%) acute lymphoblastic leukemia-like regimens; 8 patients (12%) were treated with lymphoma-like regimens; 6 (9%) received medication within clinical trial; 2 (3%) compassionate use of Tagraxofusp, and 9 (13%) supportive care only. Among 59 treated patients, front-line treatment resulted in 27 (47%) complete remission, 1 (2%) morphologic leukemia-free state (MLFS), 6 (10%) partial remission, 14 (24%) showed resistance, 7 (12%) died during induction (causes of death were cerebral bleeding [3] and multiorgan failure [4]), and 4 (7%) had not available response. Of among 42 treated patients with available post-remission treatment, 9 (21%) received an allogeneic hematopoietic stem cell transplant in first CR. With a median follow-up of 9.6 months, the median overall survival of the cohort was 8.58 months. Median OS was 6 months in patients not transplanted and not reached among those transplanted in first CR (p=0.000695) (Figure 1). Conclusions Our preliminary analysis confirms the dismal prognosis of this rare entity (median OS of 8.6 months). We found large heterogeneity of therapeutic approaches, low complete remission rates and scarce rates of allogeneic transplant in the front-line. Improvement of outcomes through well-defined treatment protocols and innovative agents are needed for this high unmet need disease.

Genetic Mutation and Outcome of Venetoclax-Based Therapy in Newly Diagnosed AML in the Real World: Hokkaido Leukemia Net Study

Introduction Venetoclax (VEN) had been approved in Japan since March 2021 for acute myeloid leukemia (AML), and VEN-based regimens were widely used as initial therapy predominantly for elderly or unfit patients. Genetic mutations affect therapeutic outcomes of VEN-based therapy (CD DiNardo, et al. Blood. 2020). We performed gene panel sequencing using a next-generation sequencer for the newly diagnosed AML patients who were initially treated by VEN-based regimen and analyzed the relationship between gene mutations and outcomes in our regional cohort. Patients and Methods Hokkaido Leukemia Net (HLN) is prospective cohort study collecting acute leukemia samples from affiliated hospitals of the North Japan Hematology Study Group (NJHSG) covering Hokkaido and Iwate, Japan. We developed a compact AML panel covering mutation hot spots of 14 genes including TP53, CEBPA, NPM1, FLT3, KIT, NRAS, KRAS, CBL, PTPN11, DNMT3A, IDH1, IDH2, RUNX1 and ASXL1. Treatment efficacy was determined based on European LeukemiaNet 2017 response criteria in AML. This study was conducted in accordance with the Helsinki Declaration and was approved by the institutional review boards. Results A total of 89 AML cases registered in HLN from May 2021 to April 2023 were initially treated by VEN-based therapy (age range, 57-90 years; median age, 75 years; 49 males and 40 females, VEN+AZA 85, VEN+AraC 4). The median overall survival (OS) for all patients was 367 days (range 12-636). Patients who achieved complete remission (CR), CR with incomplete hematologic recovery (CRi), morphologic leukemia-free state (MLFS), or partial remission (PR) during the observation period and had no relapse were designated as Group 1, those who relapsed as Group 2, and those who became Stable disease (SD) or Progressive disease (PD) as Group 3. IDH2 mutations were significantly more frequent in Group 1 (P=0.010), and NPM1 mutations also tended to be more frequent in Group 1 and 2 (P=0.064). Furthermore, the ratio of CR or CRi was more than 80% in the patients with mutation of CEBPA-bZIP, DNMT3A, IDH1, IDH2, and NPM1 mutation-positive groups, respectively. These response groups clearly stratified prognosis. On the other hand, prognostic stratification according to biological disease factors depending on National Comprehensive Cancer Network (NCCN) 2017 stratification could not stratify the VEN-treated cohort (P=0.26) (Figure 1). Next, the mutations with high CR+CRi rate ( CEBPA-bZIP, DNMT3A, IDH1, IDH2, and NPM1) were classified as “high-sensitivity mutations”. Patients with high-sensitivity mutations were significantly less likely to have complex karyotypes (P=0.026), but other patient characteristics such as age, sex, performance status, WBC count, other genetic mutations were not statistically different. Patients with high-sensitivity mutations had a significantly favorable OS than those without (median OS not reached; 95% CI, 367 - NA vs 331 days; 95% CI, 259-430, p=0.0022). Univariate analysis was carried out for age, sex, karyotype, each gene mutation and “high-sensitivity mutations”. IDH2 mutation and high-sensitivity mutations were associated with favorable OS (P=0.016, 0.0022, log-rank test). As previously reported, complex karyotypes and TP53 mutations were associated with poor OS (p&amp;lt;0.001, &amp;lt;0.001, log-rank test). Multivariate analysis including age, sex, “complex karyotype and/or TP53 mutation” and “high-sensitivity mutations” showed that the high-sensitivity mutations were independently associated with favorable OS (HR, 0.16; 95% CI, 0.053 to 0.62, p=0.0067; cox regression). Complex karyotype and/or TP53 mutation was independently associated with poor OS (HR, 2.39; 95% CI, 1.12 to 5.09, p=0.024; cox regression). Based on these results, we were able to stratify the prognosis by dividing the patients into three groups according to the presence of high-sensitivity mutations, complex karyotype and/or TP53 mutations (Figure 2). Conclusion VEN-based therapy abrogates the efficacy of NCCN2017 stratification, however, the genetic mutation profile of the initial disease successfully stratified prognosis.

Venetoclax Combined with Homoharringtonine,Cytarabine and Aclacinomycin (HAAV) As Induction Therapy in Newly Diagnosed Young Adult Acute Myeloid Leukemia

Background: The remission rate of acute myeloid leukemia (AML) patients using traditional induction chemotherapy is approximately 60-70%. Venetoclax (Ven), a b-cell lymphoma 2 (BCL-2) inhibitor, in combination with chemotherapy or hypomethylating agents, has shown a significant increase in remission rates and improvement in patient survival for elderly or unfit for intensive chemotherapy newly diagnosed AML patients. The HAA regimen (consisting of Homoharringtonine, Cytarabine and Aclacinomycin), a specific traditional induction therapy for acute myeloid leukemia in China. The HAA regimen achieved complete remission rates about 70% as an induction regimen for newly diagnosed AML. Whether the combination of Ven with HAA regimen as an induction treatment can further enhance the complete remission rate in newly diagnosed adult AML patients requires investigation through well-designed clinical trials. Objective: To evaluate the efficacy and safety of HAA combined with Ven as induction regimen (HAAV) in young adult patients with newly diagnosed AML. Design, setting and participants: Single-arm, prospective clinical trial conducted at 8 hospitals in China. Eligible patients (16-60 years old) with newly diagnosed AML (exclude acute promyelocytic leukemia) were enrolled. The trial was registered on ClinicalTrials.gov (NCT05893472) and continues to accrue patients. Induction regimen: The induction regimen consisted of Homoharringtonine (2.5mg/㎡/d，d3-7 ), cytarabine (100mg/㎡/d by continuous intravenous infusion daily on d3-7) and Aclacinomycin (20mg/d, d3-7) combined with venetoclax (100mg d1, 200mg d2, 400mg d3-8). Main outcomes and measures: The primary endpoint was the overall response rate (ORR) after once cycle of HAAV regimen, which included complete remission (CR), complete remission with incomplete count recovery (CRi), morphologic leukemia-free state (MLFS) and partial remission (PR). Secondary endpoints included minimal residual disease (MRD), overall survival (OS), event-free survival (EFS) and adverse events. Results: Untill June 30, 2023, 40 patients were enrolled. The median age is 43 years (range, 18-60), with 60% (24/40) was male. According to the European Leukemia Network prognostic group (2022), 14 (35.0%), 14 (35.0%), and 12 (30.0%) patients were considered to belong to the favorable, intermediate, and adverse groups, respectively. Further details of the patients' characteristics are provided in Table 1. The ORR (CR+PR) was 97.5% (39/40 patients) after one cycle of the induction regimen with the CR rate was 95.0% (38/40). According to the ELN prognostic group (2022), the CR was 100% in favorable-risk patients (14/14), 100% in intermediate-risk patients (14/14), and 83.3% in adverse-risk patients (10/12). For patients who achieved CR, MRD negative rate was 88.9% (32/36) by flow cytometry. During the induction treatment, all patients experienced ≥Grade 3 hematological toxicity, the remaining common adverse reactions were infections and fever. None of patients died during the induction therapy. In patients who achieved response, the median time to recovery of the white blood count (WBC) to ≥1.0 × 10 9/L and the platelet count to ≥20 × 10 9/L after induction therapy was 13 (range: 10-52) and 13 days (range: 2-33), respectively. ( Table 1) Conclusions: Ven combined with HAA (HAAV) is a highly effective and safe induction therapy for young adult patients with de novo AML. To the best of our knowledge, this is the first report about Ven combined with HAA.

Clonal Dynamics and Deterministic Clinical Fate Mapping of Patients with Myelodysplastic Neoplasms and Acute Myeloid Leukemia with TP53 Disruption

Background: Myelodysplastic neoplasms (MDS) and acute myeloid leukemia (AML) with multi-hit TP53 comprise the highest risk subgroup of all myeloid malignancies. TP53 aberration is recognized as a diagnostic category in the 2022 International Consensus Classification (ICC) and the 5 th edition of the WHO. However, these systems do not discern among the subtypes of TP53 aberrations regarding response to therapy. In this study, we explore the clonal dynamics that underlie such prognostic heterogeneity within distinct subgroups of TP53-aberrant MDS and AML, with a specific focus on the effect of hypomethylating agent (HMA) vs. araC-based chemotherapy on TP53 variant allele frequency (VAF). Methods: The UMass Leukemia Registry from the UMass Data Lake identified 76 patients harboring TP53 aberration(s) plus ICD-10 code of either D46.9 (MDS and its subentities) or C92.00 (AML and its subentities) between 2011-2023. Data was integrated with hematopathology records. TP53 exome sequencing was performed with coverage depth 500X to 6500X, and VAFs were adjusted for copy number variation (CNV), as previously described (Patel SA et al., Leuk Lymphoma 2021; 62: 3348-60). Patients with serial bone marrow biopsy samples were included. We defined multi-hit TP53 status as per the ICC: two or more distinct TP53 mutations with VAF ≥ 10%, or a single TP53 mutation plus one of the following abnormalities: (1) del(17p13.1), (2) TP53 VAF &amp;gt;50%, (3) copy-neutral loss-of-heterozygosity, or (4) any complex karyotype. Clonal dynamics were assessed for MDS vs. AML and for varying TP53 allelic states as a function of therapeutic intervention. Clinical fate mapping was performed based on management decisions at various points of clinical care. Results: For patients with TP53-aberrant MDS, 17 patients underwent serial bone marrow biopsies during treatment. Of these, 11 (64.7%) had multi-hit status. Eight patients (47.1%) underwent hematopoietic cell transplant (HCT), and 7 of these 8 patients had received HMA-based front-line therapy. For patients with MDS, we assessed the effect of HMA-based therapy on TP53 VAF. The mean TP53 VAF (sum of VAFs) was significantly lower after HMA-based treatment (35% vs. 12.6%) ( p = 0.0075) (Panel A). For patients with TP53-aberrant AML, 19 patients underwent serial bone marrow biopsies. Of these, 14 (73.7%) had multi-hit status. Only 2 patients (10.5%) underwent HCT. Five patients (26.3%) received araC-based induction, while 11 patients (57.9%) initially received HMA-based induction. For patients with AML with multi-hit TP53, we assessed the effect of HMA-based vs. araC-based front-line therapy on TP53 VAF. HMA therapy led to mean fold reduction in TP53 VAF (pre-treatment to post-treatment) of 11.7 ± 5.8 ( p = 0.019), while araC-based therapy actually led to mean fold increase (but not statistically significant) in TP53 VAF (pre-treatment to post-treatment) of 2.6 ± 1.05 ( p = 0.319) (Panel B). HMA-based treatment resulted in significantly greater reduction in the VAF in aberrant clones and subclones compared to araC-based treatment. Compared to AML, most patients with MDS (62.9%) proceeded with palliative intent therapy at the time of diagnosis. Although patients with AML (53.7%) attempted to proceed with curative intent at the time of diagnosis, only 14.6% eventually proceeded with HCT, largely due to clinical decompensation or disease progression during front-line therapy. Among HCT recipients for MDS ( n =10), 7 (70%) remained in remission. Among HCT recipients for AML (n = 6), 4 (66.7%) remained in morphologic leukemia-free state. Conclusion: There is limited literature on clonal and subclonal diversity in patients with MDS or AML with TP53 aberrations. Such considerations constitute an important therapeutic issue, as certain interventions may only eliminate a fraction of a patient's mutant cells. In our study, HMA- and araC-based regimens had differential effects on various subclones: HMA was more effective in reducing the TP53 mutational burden and increasing patient ability to proceed with HCT. AraC-based therapy appeared less effective, perhaps due to selection pressure in favor of TP53-mutant cells. Prospective trials are required to identify optimal regimens that lead to the best long-term outcomes, and single-cell resolution might assist with more definitively assessing dynamics of clonal response to treatment.