Secondary Acute Myeloid Leukemia Research Articles

Venetoclax Plus Azacitadine for Middle Aged and Elderly Patients with Newly Diagnosed Acute Myeloid Leukemia: Interim Analysis of a Prospective, Multicenter, Single-Arm, Phase 2 Trial

Background: “7+3” induction is the standard regimen in newly diagnosed young patients (pts) with acute myeloid leukemia (AML) fit for intensive chemotherapy with 60-80% complete remission rate. However, middle aged and elderly pts may experience more severe complications during induction therapy and overall survival is shorter than that of younger pts. Recently, venetoclax with azacitadine as induction therapy was approved as the first line therapy for pts with aged more than 75 years or unfit pts with composite complete remission (CRc) of 60-70%. We hypothesize that venetoclax with azacitadine as induction therapy in fit middle aged and elderly pts may have similar CRc rate and less complications. This study aims to evaluate the safety and efficacy of venetoclax plus azacitadine as induction therapy in fit middle aged and elderly newly diagnosed AML pts. Methods: This is an interim analysis of an ongoing phase 2 clinical trial (NCT05471700) of a planned 40 untreated AML pts aged 45-65 who were fit for intensive chemotherapy according to Ferrara Criteria. In cycle 1, pts received azacitadine 75mg/m2/day on d1-7 and venetoclax escalated from 100mg to 200mg to 400mg until 28-day cycle was finished. For pts with FLT3-ITD positive, sorafenib was optional administered at a dose of 400mg twice daily. Bone marrow assessments were performed on d28. Pts who achieved CRc (defined as complete remission[CR] and CR with incomplete hematologic recovery[CRi]) with intermediate or adverse risk groups received 1 or 2 cycles of consolidation with venetoclax plus azacitadine or center-specific cytarabine-based consolidation. Allogeneic stem cell transplantation (HSCT) was performed if a donor was available. Pts in favorable risk gruop received 3 to 4 cycles of center-specific intermediate or high dose cytarabine-base consolidation. Non-responders or pts who achieved partial remission received 1 more cycle of venetoclax plus azacitadine. Who could not get CRc after 2 cycles of induction would be withdrawn from the study. The primary objective is to determine the CRc rate. The secondary objective is safety, MRD negative rate, duration of remission (DOR), the rate of allo-HSCT, event free survival (EFS), and overall survival (OS). The endpoint is to show that venetoclax plus azacitadine is not inferior to “3+7” induction in fit pts with newly diagnosed AML aged 45-65. Results: From 10/9/2022 to 6/30/2023, a total of 32 pts was enrolled to this study, comprising 18 males and 14 females. There were 27 (84%) pts with de novo AML, 2(6%) pts were secondary AML, 3 pts (9.4%) were therapy-related AML. Median age was 58 years (range, 45-64 years). There were 2(6%), 14(44%) and 16(50%) pts were in the favorable, intermediate and adverse risk group, respectively. The baseline patient characteristics are summarized in Table 1. Outcome data were updated as of June 30, 2023, for a median follow-up of 2.2(0.2-8.8) months. Among 27 evaluable pts, 21(77.8%) achieved CRc with 11(40.8%) in CR and 10(37.0%) in CRi, 2(7.4%) achieved PR in cycle1, while 23(85.2%) achieved CRc with 14(51.9%) in CR and 9(33.3%) in CRi, 4(14.8%) got induction failure after 2 cycles(Figure 1). A total of 16 (61.5%) pts got MRD negative among the pts with CRc after cycle1, and 17 (65.4%) after cycle2. CRc rate after 2 cycles in ELN2017 favorable, intermediate, adverse risk group was 100%, 83.3% and 85.0%, respectively, and MRD negative rate was 100%, 88.9% and 55.6%, respectively. The regimen was well tolerated. No mortality occurred during induction therapy. The most common non-hematological grade 3/4 AE were febrile neutropenia (n=13, 40.6%)，followed by pneumonia (n=3, 9.4%).Sepsis occurred in 1 (3.1%) pt. With a median follow-up of 2.2(0.2-8.8) months, the median remission duration, EFS and OS have not been reached. Conclusions: Preliminary results indicate that venetoclax plus azacitadine as an induction regimen for fit middle aged and elderly pts with newly diagnosed AML is promising with high CRc and low toxicity. Recruitment of adults with newly diagnosed aged 45-65 AML pts for this trial is ongoing.

Unmet Medical Needs Amongst Older Patients Aged ≥60 Years with Newly Diagnosed Acute Myeloid Leukemia Receiving Intensive Chemotherapy: Experience from a Predominately United States Community Setting

Background: Venetoclax (Ven) in combination with hypomethylating agents is approved for treatment in patients (pts) with newly diagnosed (ND) acute myeloid leukemia (AML) who are ≥75 years old or unfit for intensive chemotherapy (IC), based on the longer median overall survival (OS) with Ven+azacitidine (Aza) compared with Aza in combination with placebo in the Phase III VIALE-A study (NCT02993523). Several studies are now evaluating Ven-based regimens in pts eligible for IC, for example Ven+Aza compared with IC (NCT04801797). Additionally, Ven in combination with cladribine (CLAD) and low-dose cytarabine (LDAC) is currently under investigation in a Phase II single-arm study (NCT03586609) amongst older pts (aged ≥60 years) with ND AML. An interim analysis of this trial evaluated 60 pts where complete remission (CR) and CR with incomplete count recovery (CRi) was observed in 93% of pts, and the median OS, overall and by transplant status, was not reached; 1-year OS was 72.9% and 2-year OS was 63.5% (Kadia et al. J Clin Oncol 2022). The aim of this study is to better understand treatment outcomes amongst older pts (aged ≥60 years) with ND AML receiving IC in a routine clinical care setting in the United States (US). Methods: This was a retrospective cohort study using the Flatiron Health electronic health record-derived, US nationwide, de-identified database. Pts aged ≥60 years with ND AML who initiated IC within 60 days of AML diagnosis (Dx) between January 1, 2014, and November 30, 2022, with ≥2 visits recorded within 3 months of AML Dx, and ≥3 months of follow-up before study end date (February 28, 2023) were included. Clinical trial participants and pts with acute promyelocytic leukemia or core binding factor were excluded. Descriptive analysis on patient characteristics was conducted. The proportion of pts who achieved real-world response (defined as <5% bone marrow [BM] blasts), real-world CR/CRi (defined as <5% BM blast with either platelet count <100 x 10 9/L or absolute neutrophil count <1000 x 10 9/L) and received a stem cell transplant (SCT) post-remission were reported. Thirty-day mortality, 60-day mortality, 1-year real-world OS (rwOS), and 2-year rwOS were evaluated using Kaplan-Meier (KM) analyses. The starting points for KM analyses were IC treatment initiation (all pts), SCT (pts who underwent SCT post-remission), and remission (pts who did not undergo SCT post-remission). Pts were censored at the last activity date or SCT date (whichever occurred earliest) for the overall patient cohort, and the last activity date for pts with or without SCT post-remission. Results: A total of 1105 pts met the study criteria. The median (IQR) age was 67 (64-71) years, 57% were male, 27% had secondary AML, 48% had BM blast >50% at Dx, and 66% were treated in the community setting. Excluding 340 pts with unknown cytogenetic and molecular data, 19%, 32%, and 48% of pts had European LeukemiaNet 2017 favorable, intermediate, and adverse risk, respectively. At a median (IQR) follow-up of 13 (6-28) months from AML Dx, 74% (n=821) of pts achieved real-world response, including 66% (n=724) who achieved real-world CR/CRi. For all pts, the 30-day mortality was 3%, 60-day mortality was 6%, 1-year rwOS was 58%, 2-year OS was 34%, and the median rwOS was 14.3 months ( Figure A). A total of 37% (n=306/821) of pts underwent SCT post-remission; 98% (n=300/306) underwent allogeneic-SCT and 2% (n=6/306) underwent autologous-SCT. The median rwOS was 40.4 months for pts undergoing SCT post-remission, and 13.8 months for pts without SCT post-remission ( Figure B). Conclusions: In this large real-world data study, we observed older pts (aged ≥60 years) with ND AML receiving IC treatment had a median OS of <14 months and <35% of pts remained alive 2 years after IC initiation. Findings from this study suggest the need for other novel treatment options, including Ven based regimens, to improve OS in older pts (aged ≥60 years) with ND AML who are eligible for IC. Future studies are warranted to conduct randomized controlled trials to comparatively evaluate IC vs other novel treatment options in older pts (aged ≥60 years) with ND AML, or conduct the appropriate statistical adjustment to minimize confounding in indirect treatment comparisons from different studies.

Clinical Outcomes and Cardiovascular Adverse Events of Patients with Acute Myeloid Leukemia Treated with Venetoclax Plus a Hypomethylating Agent or Low-Dose Cytarabine in the Veterans Health Administration: A National Retrospective Cohort Study

Background: Acute myeloid leukemia (AML) is the most common acute leukemia in adults with a median age at diagnosis of 68 years. Standard curative treatment consists of intensive induction chemotherapy followed by consolidation, allogeneic stem-cell transplantation, or both. However, older patients may be ineligible for intensive chemotherapy due to impaired performance status or significant comorbidities. For those medically unfit, the combination of venetoclax plus a hypomethylating agent (VEN + HMA) can be used based on the results of the phase 3 VIALE-A clinical trial (PMID: 32786187). With a median follow-up of 20.5 months, azacitidine-venetoclax achieved superior OS than azacitidine monotherapy (14.7 versus 9.6 months; HR 0.66; 95% CI 0.52-0.85; P<0.001). The only cardiac event reported was atrial fibrillation in 5% of patients. Our retrospective study explores real-world clinical outcomes and new cardiovascular adverse events of patients treated with venetoclax plus either azacitidine, decitabine, or LDAC (VEN + LDAC) in the Veterans Health Administration (VHA). Methods Medical records of 198 veterans who were patients in the VHA and treated with VEN + HMA or VEN + LDAC between January 1, 2016, and December 31, 2021, were randomly selected and reviewed. Patients with a diagnosis of AML who received front-line therapy were included. Patients with acute promyelocytic leukemia were excluded. Overall survival (OS) was defined as the period between the date of diagnosis and the date of death from any cause and was estimated using the Kaplan-Meier method. Cardiovascular adverse events were characterized as those that occurred from the first dose until 30 days after discontinuation of treatment. Results A total of 101 patients were included. The median age at diagnosis was 74 years, 98% were male, 48% presented with de novo AML, 64% had an Eastern Cooperative Oncology Group performance-status score ≤ 1, and 52% had poor cytogenetic risk according to the European LeukemiaNet (ELN) 2017 stratification. Azacitidine was used in 62% of patients, decitabine in 34%, and LDAC in 4%. Based on the common terminology criteria for adverse events (CTCAE) version 5, 28% of the cohort had grade ≥3 (≥G3) anemia, 36% ≥G3 thrombocytopenia, and 62% ≥G3 neutropenia. The median OS was 8.5 months (95% CI:6.4-12.3). Those who received azacitidine had an OS of 7.7 months (95% CI: 5.6 - 12.4) versus 10.7 with decitabine (5.3 - 19.9), however the difference was not significant (p=0.29). Twenty-five percent of patients experienced at least one new cardiovascular adverse event. Of those, 11% already had a cardiovascular comorbidity at baseline. The most common adverse events were atrial fibrillation in 9%, non-ST elevation myocardial infarction in 4%, cardiopulmonary arrest in 3%, cardiogenic pulmonary edema in 2%, and LVEF decrease in 2%. Conclusion This is the first study to analyze the OS and the array of new cardiovascular events of patients with AML treated with VEN + HMA or VEN + LDAC in the VHA. Our national retrospective cohort study showed an inferior median OS and more new adverse cardiovascular events in patients treated with VEN + HMA than what was seen in the VIALE-A study. This is likely due to the clinical design of the phase 3 trial. Furthermore, we had a higher percentage of patients with secondary AML and poor cytogenetic risk which are known adverse prognostic factors. The limitations of this study include its retrospective and observational nature with data that was created for patient care, not research, and might contain missing information. Besides, the VHA sites are exclusively located in the United States and the cohort is mainly composed of male patients which is not fully applicable to the general population. Further studies are needed to determine the real-world OS and profile of cardiovascular adverse events of venetoclax combination therapy.

Acute Myeloid Leukemia with Inv(3) or t(3;3): A Clinical and Cytogenetic Characterization of 40 Patients

Background: Acute myeloid leukemia (AML) with inv(3) or t(3;3) is an extremely aggressive and rare subtype of AML. Leukemogenesis in inv(3) AML is in part due to juxtaposition of the GATA2 enhancer in close proximity to the MECOM/EVI1 promoter; as the result, the fusion drives EVI1 overexpression and uncontrolled proliferation of myeloid progenitors. Given its rarity, published clinical outcome data are limited. To improve our understanding of the clinical outcomes of inv(3) AML, we conducted a retrospective study to describe the clinical features of a cohort of newly diagnosed inv(3)/t(3;3) AML patients treated at Stanford Cancer Center between 2002 and 2023. Methods: Data were retrospectively collected from databases associated with the Stanford Health Care electronic health record (EHR), and diagnosis dates came from the Stanford Cancer Registry. Inv(3)/t(3;3) AML diagnosis was defined according to WHO criteria as the presence of ≥20% blasts in the bone marrow (BM) or peripheral blood (PB) and the presence of inv(3)(q21.3q26.2) or t(3;3)(q21.3;q26.2) on cytogenetic analysis at initial diagnosis. Response to first induction, salvage, and consolidation therapy as well as allogeneic hematopoietic stem cell transplant (alloHSCT) were captured. CR was defined as the presence of <5% of blasts in the BM evaluation by morphological evaluation after each line of treatment. Overall survival (OS) was defined as time from diagnosis to death from any cause. A descriptive study of the main demographic, clinical, hematologic, and cytogenetic variables of patients who received intensive and non-intensive therapy was performed. The analysis was performed using R 4.3.1. A p value of < 0.05 was defined to be statistically significant. Results: A total of 40 patients met inclusion criteria including 68% (n=27) with de novo AML, 25% (n=10) with secondary AML from an antecedent hematological disorder and 7.5% (n=3) therapy-related AML. Clinical characteristics of the patients are summarized in Figure 1A. The median age at time of diagnosis was 56 (range, 19-78). There was a slight female predominance, with 58% (n=23) female and 42% (n=17) males. Ninety-three percent of patients had an ECOG score ≤1 (n=37). Median leukocyte, hemoglobin, and platelet counts were 4.5 K/uL, [1.3-761], 9.4 g/dL, [3.4-13.6], and 98 K/uL [9-592], respectively. The median blast percentage in BM and PB was 49% [13-98] and 30% [0-95], respectively. Inv(3)/t(3;3) was the only cytogenetic aberration in 10 patients (25%) and chromosome (chr) 7 abnormalities were the most common additional aberration, present in 22 patients (55%). CR after the first induction therapy was achieved in 9 patients (22%); 6 patients (15%) died during or shortly after induction therapy, and the remaining 25 (63%) were resistant. Salvage therapies for patients included re-induction with 7+3, FLAG-Ida, mitoxantrone-containing regimens, clofarabine-based protocols, or combination of hypomethylating agents with venetoclax. Seventeen (43%) patients underwent alloHSCT (10 in CR and 7 with active disease). When comparing intensive vs non-intensive induction regimen, no statistical significance was identified for complete remission (CR) rate (p= 1.00), overall survival (OS) rate (p=0.65) or relapse-free survival (RFS) rate (p=0.86). Similarly, no statistically significant prognostic factors (age, WBC, BM blast %, platelet count, hemoglobin, ANC, or time to transplant) for OS were identified. Interestingly, chr 7 abnormalities in inv(3) patients conferred a worse prognosis in this cohort (OS 41% vs. 59%, p= 0.0064, Figure 1B). This association was confirmed using a multiple Cox proportional hazards regression adjusting for age and blast percentage. Moreover, while chr 7 abnormality was also associated with a lower response rate (CR 14% vs. 40%), it did not reach statistical significance (p=0.12). Conclusions: In summary, de novo AML inv(3)/t(3;3) is a rare and aggressive subtype of AML conferring extremely poor prognosis. There appears to be an increase of incidence in females affecting a slightly younger demographic. Consistent with previous studies, the presence of chr 7 abnormalities was associated with even worse outcomes, which interestingly also drive EVI1 overexpression. The exact link between 3q26 loci rearrangements and chr 7 abnormalities warrants further investigation.

Characteristics and Clinical Outcomes of Patients with Acute Myeloid Leukemia with TP53 Mutations - a Single Center Experience

Introduction TP53-mutated acute myeloid leukemia (AML) carries a dismal prognosis. Optimal induction therapy is uncertain, and it remains unclear whether allogeneic stem cell transplant (allo-SCT) improves survival. Methods We investigated 89 cases of TP53-mutated AML diagnosed at or referred to Thomas Jefferson Hospital between April 2016 and May 2023 and reviewed clinical characteristics and outcomes. Remission status was determined by bone marrow biopsy and aspiration after at least 1 cycle of anti-leukemic therapy (ALT). ALT was classified into high- or low-intensity treatment. High-intensity treatment was defined as regimens containing high-dose cytarabine (≥ 200 mg/m 2/day) for at least five consecutive days in combination with an anthracycline. Low-intensity treatment was defined as hypomethylating agent (HMA)-based therapy containing either azacitidine or decitabine with or without venetoclax. Results Median age at diagnosis was 66 (range, 23-91). Forty-nine percent had de novo AML, and the rest had secondary AML. Ninety-one percent had newly diagnosed AML and 9% were found to have a TP53 mutation at relapse. Median somatic mutation count as detected by next-generation sequencing (NGS) was 2 (range, 1-9). Thirty percent were treated with high-intensity treatment, 46% with low-intensity treatment, and 22% received supportive care only. Detailed patient characteristics are in Table 1. Median overall survival (OS) for the entire group was 3.17 months [95% confidence interval (CI) 1.90-5.13 months], and 5.13 months (95% CI 3.83-8.00 months) for patients who received any ALT. Of 69 patients who received ALT, composite complete remission (CRc) rates were 26% with high-intensity treatment and 34% with low-intensity treatment ( p = 0.56). Fifty-six percent did not achieve a remission, and 12% were not able to be assessed due to early mortality. The 30-day mortality was 15% and 7% with high- and low-intensity treatments, respectively. OS was not different between patients who received high- and low-intensity treatments (5.13 months vs 5.27 months, p = 0.65). Twenty-four percent underwent allo-SCT with a median follow-up of 15.2 months. The median time to transplant was 180 days from time of diagnosis (range, 119-341). Median hematopoietic cell transplantation-specific comorbidity index was 3 (range, 1-7). The majority of patients (69%) received a reduced intensity or non-myeloablative regimen, and 63% received a haploidentical transplant. Eighty-one percent of transplant recipients were in CR or CR with incomplete count recovery at the time of transplant; the remaining had either primary induction failure or relapsed disease. Median OS was significantly longer for patients who received allo-SCT compared to those who received chemotherapy only (18.0 months vs 3.7 months, p <0.0001) (Figure 1). Cumulative incidence of relapse post-transplant was 36% at 1 year and 79% at 2 years. Conclusions TP53-mutated AML is associated with a dismal outcome. In our single-center analysis, approximately one-third of patients achieved remission after initial ALT. Consolidation with allo-SCT is associated with improved survival, however relapse risk remains high. Treatment strategies aimed at reducing disease relapse post-transplant are warranted.

Maintenance Therapy with Chidamide Plus Azacitidine after Allogeneic Hematopoietic Stem Cell Transplantation for High-Risk Acute Myeloid Leukemia Patients

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is theoretically the only curative option for high-risk acute myeloid leukemia (AML) patients. However, many patients relapse after allo-HSCT, and treatment options are very limited. Azacitidine, a DNA methyltransferase inhibitor exhibits anti-leukemia activity in myeloid diseases. Chidamide, a selective histone deacetylase inhibitor, effectively induces apoptosis of AML cells. They have synergistic inhibitory effect on AML cells when combined together. Therefore, we conducted a multicentre, prospective study (ChiCTR2300067593) to examine the tolerability and efficacy of a combination of both chidamide and azacitidine as a maintenance therapy for high-risk AML patients after allo-HSCT. Patients and methods： Patients ≤ 60 years of age with high-risk AML post- allo-HSCT were enrolled. The high-risk characteristics of AML were defined as one or more of the following criteria: a) Patients with poor prognosis according to the genetic risk stratification assessment of European Leukmia Net (ELN) in 2022; b) Primary refractory or recurrent AML; c) Secondary AML (secondary to MDS or treatment-related AML). All patients received Chidamide 5 mg/d combined with azacitidine 75 mg/m2/d for 5 days. The cycle interval was 6-8 weeks. A total of 6 cycles was recommended. Treatment started as early as 3 months after transplantation. The primary endpoint of this study was cumulative incidence of relapse (CIR). The secondary endpoints included rates of overall survival (OS) and event-free survival (EFS). Survival outcomes were estimated using Kaplan-Meier analysis. Results： Thirty-six patients have been recruited. The median age was 42 years (range, 16-59). Baseline characteristics are shown in Table 1. With a median follow-up time of 412（185-762）days, the 1-year CIR was 12.3 (6.5-18.1) %, the 1-year OS and EFS rates were 100.0% and 87.7 (81.9-93.5) %, respectively. The median OS and EFS time were not reached. Four patients relapsed, two died, and two are still alive and ready for the second transplantation. The most common adverse events (AEs) were thrombocytopenia reaction and gastrointestinal tract reaction. Grade 2 or 3 AEs were observed in 16.7% (6/36) and 25.0% (9/36) of the patients, respectively. No grade >3 AEs were noted. 9 patients (6/36,16.7%) developed grade 3-4 thrombocytopenia, without active hemorrhage. All of them received blood transfusion and thrombopoietin receptor agonist. The median persistence of thrombocytopenia was 3 (2-5) d. Chronic graft-versus-host-disease (cGVHD) occurred in 25.0% (9/36) of patients. Four cases (4/36, 11.1%) were complicated with infection. They were one case of intestinal infection, one case of pulmonary and EBV infections, one case of hepatitis B virus activation and one case of herpes zoster. And all infected patients recovered safely after anti-infection and symptom-oriented treatment. CMV activation was not observed. Non relapse mortality (NRM) was zero. Conclusions： We conclude that chidamide plus azacitidine can be administered safely after allo- HSCT with no evidence of an increased incidence of GVHD, and this combination may decrease the relapse rate in high-risk AML patients. This novel maintenance therapy may be a promising way to prevent relapse in high-risk AML patients.

Selinexor in Combination with Venetoclax and Azacitidine for Newly Diagnosed (ND) Unfit Acute Myeloid Leukemia (AML): A Multicenter, Open-Label Prospective Study

Introduction: Acute myeloid leukemia (AML) predominantly affects the elderly, with a median age at diagnosis around 68 years (Bhansali, 2023). Due to existing or potential comorbidities and frailty, many patients are unable to undergo conventional intensive chemotherapy at the time of diagnosis. The combination of venetoclax with azacytidine has shown improved clinical response rates of 64% with a median overall survival of 14.7 months (DiNardo, 2020). However, subgroup data demonstrated no significant benefits in the Chinese population, in pts with poor risk, or in those with TP53 mutations. Therefore, managing AML in elderly or unfit pts remains a significant challenge. Selinexor has shown promising tolerability and clinical activity in AML through various phase 1/2 trials. The triple regimen of selinexor, venetoclax, and azacytidine (SAV) has demonstrated favorable results in AML pts with severe co-morbidities in real-world settings. To further evaluate its efficacy and safety, we have designed a prospective study (NCT05736965) to assess the SAV regimen for ND AML pts who are ineligible for intensive therapy. Methods: To report the efficacy and safety of ND AML pts ineligible for intensive chemotherapy, treated with a triple regimen from 6 sites. The study enrolled pts who were unfit for intensive chemotherapy, ≥75 years, had significant comorbidities, an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of ≥3, organ dysfunction, or had abandoned intensive chemotherapy. The primary study objectives were the complete response (CR)/complete response with incomplete count recovery (CRi) rate and overall response rate (ORR). Responses were assessed according to the ELN2022 criteria. Pts received the following treatment regimen: Selinexor 60mg on days 3, 10, and 17; Azacitidine 75mg/m2 on days 1-3, 8-9, and 15-16; Venetoclax 100mg on day 1, 200mg on day 2, and 400mg on days 3 to 14. Each treatment cycle lasted for 28 days. Pts who achieved CR, CRh, or CRi, as per the center's treatment guidelines, were eligible for transplantation at any time point. Remaining pts continued to receive the SAV regimen until disease progression or intolerable toxicity. Results: From March 2023 to the data cutoff on June 10, 2023, a total of 20 pts were enrolled in the study, of which 16 had de novo or therapy-related AML, and 4 had secondary AML with a history of myelodysplastic syndrome. Table 1 displays the baseline characteristics and responses of the newly diagnosed AML pts. The median age of the 20 pts was 64 years (range: 28-80), and the majority of them had high-risk disease: 12/20 (60%) had intermediate-risk, and 8/20 (40%) had adverse-risk according to the ELN 2022 criteria. Additionally, 4/20 (20%) of the pts had therapy-related AML, 6/20 (30%) were aged ≥75 years, 12/20 (60%) had ≥2 high-risk molecular mutations, and a significant proportion had high blast counts. All pts completed at least 1 cycle of treatment (range: 1-4). Specifically, 1patient completed 4 cycles, 2pts completed 3 cycles, and 7pts completed 2 cycles. The remaining 10pts have just completed their first cycle of treatment and evaluation. With the exception of one patient with disease progression (PD), all other pts are still undergoing treatment. As the treatment duration extends, the depth of remission in pts may further deepen. The CR/CRi rates and ORR across the ELN 2022 risk groups for all pts, intermediate-risk group, and adverse-risk group were as follows: 80% (16/20) and 90% (18/20), 75% (9/12) and 91.7% (11/12), 87.5% (7/8) and 87.5% (7/8), respectively. In comparison, the VIALE-A data showed a CR/CRi rate of 52.9% for adverse-risk pts, indicating a higher remission rate observed in this study. As of now, 3 pts were MRD-negative. The reported adverse events of grade 3 or higher occurring in ≥10% of pts in the triple regimen were thrombocytopenia (35%), neutropenia (35%), and infections (15%). The most frequently reported adverse events of Grade 1-2 included anemia, nausea, fatigue, anorexia, and hyponatremia. All adverse events could be managed and improved through dose adjustments and supportive treatment. Conclusions: The SAV regimen has been found to be safe and effective, with encouraging complete response (CR) rates in newly diagnosed AML pts, especially in adverse risk patients. Further trial enrollment and correlative analysis are currently underway to thoroughly observe the efficacy and safety of the SAV regimen.

Tagraxofusp in Combination with Azacitidine and Venetoclax in Newly Diagnosed CD123+ Acute Myeloid Leukemia, Expansion Cohort of a Phase 1b Multicenter Trial

Background: CD123 is a subunit of the interleukin 3 (IL3) receptor expressed on the surface of blasts in most acute myeloid leukemias (AMLs). Tagraxofusp (TAG), a CD123-directed therapy, is a recombinant protein drug consisting of IL3 fused to a truncated diphtheria toxin payload approved for treatment of blastic plasmacytoid dendritic cell neoplasm. We found TAG resistance in AML cells was mediated by DNA methylation and silencing of diphthamide genes (e.g., DPH1), which causes resistance to diphtheria toxin (Togami, JCI 2019). The hypomethylating agent azacitidine (AZA) reversed TAG resistance, and TAG plus AZA prolonged survival vs. either alone in xenograft models. TAG-exposed AML cells were also sensitized to the BCL2 inhibitor venetoclax (VEN). We performed a phase 1b trial combining these agents in myeloid malignancies and reported acceptable safety in dose escalation of TAG with AZA-VEN (ASH 2021). Here, we report an expansion cohort in newly diagnosed AML treated with TAG-AZA-VEN. Methods: Patients (pts) were adults with AML ineligible or declining intensive induction chemotherapy. CD123+ blasts were required (tested locally by flow or IHC, any level). Eligibility included albumin >3.2 g/dL and normal cardiac ejection fraction. Pts were treated on 28-day cycles with AZA 75 mg/m2 d1-7, VEN 400 mg d1-21 with ramp up in cycle 1, and TAG 12 µg/kg d4-6 ( Fig A), with cycle 1 hospitalization to mitigate risks of capillary leak syndrome (CLS). Also included are 3 pts who received TAG 7 µg/kg (n=2) or 9 µg/kg (n=1) in escalation. TAG was given on d4 to avoid VEN ramp up overlap and because preclinical data showed AZA pretreatment can sensitize AML cells to TAG. Results: 26 pts with AML were treated; median age 71 (range 60-81). All were adverse risk per ELN 2022 criteria, including 13 (50%) with a mutation in TP53 and others with 1 or more of ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, or U2AF1. Eight (31%) had complex karyotype, 8 (31%) secondary AML, and 5 (19%) therapy-related AML. Adverse events (AEs) were like those seen with TAG or AZA/VEN, without evidence of exacerbation by combination. Grade 3+ AEs occurring in >15% of pts regardless of attribution included thrombocytopenia (54%), leukopenia (54%), febrile neutropenia (35%), and anemia (31%). CLS, a known TAG side effect, occurred in 19% (n=5; three grade 2, one gr 3, one gr 4; all in cycle 1) and was manageable by albumin supplementation and diuresis. Mortality at 30 days was 11.5%, with causes of death of sepsis (n=2), multiorgan system failure (n=1). 18 of 26 pts (69%) achieved a best response of CR (10; 39%), CRi (5; 19%), or MLFS (3; 12%). Of the 13 with TP53 mutation, 7 (54%) achieved CR/CRi/MLFS (CR=4, CRi=2, or MLFS=1). Bone marrow blasts decreased in all pts who had a biopsy after starting treatment ( Fig A). For the 18 achieving CR/CRi/MLFS, the median duration of response was 12.4 months (mo) (95% CI, 6.1-NA). 13 of 26 (50%) proceeded to allogeneic stem cell transplantation, which included 6/13 (46%) with TP53 mutation. The median number of cycles was 3 for both pts who did (range 1-15) and did not (range 2-4) proceed to transplant. The median follow-up was 10.7 mo, including post-transplant timepoints. Median overall survival (OS) was 14 mo (95% CI, 9.5-NA) and progression-free survival (PFS) was 8.5 mo (95% CI, 5.1-NA). In pts with TP53 mutation, median OS was 9.5 mo (95% CI, 1.8-NA); and not reached (NR) without ( Fig B). PFS for pts with TP53 mutation was 5.1 mo (95% CI, 1.8-NA), and 13.3 mo (95% CI, 8.6-NA) without. Measurable residual disease (MRD) was assessed by flow cytometry in 17 pts who achieved CR/CRi/MLFS; 12/17 (71%) were MRD negative (<0.1%). 4/7 (57%) with TP53 mutation achieving CR/CRi/MLFS were MRD negative. Median OS for pts who became MRD negative was NR. Median OS for the 13 pts who received allogeneic transplant was 18.2 mo (95% CI, 14.0-NA). Median PFS for the transplanted pts was 13.3 mo (95% CI, 8.2-NA). Conclusions: Treatment of AML with triplet TAG-AZA-VEN is feasible and shows encouraging activity as up-front therapy in adverse risk AML, including in pts with TP53 mutation. These data (OS 14 mo; TP53 mutant OS 9.5 mo) compare favorably to HMA/VEN in ELN adverse risk (OS 12 mo; Lachowiez, BloodAdv 2023) or TP53 mutant AML with poor risk cytogenetics (OS 5.2 mo; Pollyea, CCR 2022), albeit with some differences between populations. No new safety signals were observed. Further development of this combination is warranted, including directly compared to AZA-VEN.

Azacitidine Combined with Novel Flavonoid Derivative GL-V9 Demonstrated Synergistic Anti-Leukemia Effect in Acute Myeloid Leukemia By Targeting DDIT4/mTOR Signaling

Background Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by the clonal expansion of malignant progenitor cells and impaired cell differentiation. GL-V9, a nature compound derived from wogonin, has shown superior anti-tumor potential by inhibiting cancer cell growth. Azacitidine (AZA), a DNA hypomethylation agent, has demonstrated therapeutic efficacy against AML. In this study, we investigated the anti-leukemia effect and potential mechanism of AZA combined with GL-V9 in AML cells, aiming to provide evidence for future clinical treatment. Methods We employed Cell Counting Kit-8 (CCK-8) to assess cell viability, Annexin-V/PI staining followed by flow cytometry analysis to measure apoptosis. CalcuSyn analysis was used to evaluate the synergistic effect. RNA-seq was performed in U937 cells and differentially expressed genes (DEGs) were identified and subjected to KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. RT-qPCR and Western Blot were used to examine gene expression. Results Our results demonstrated significant cell proliferation arrest in U937 and MV4-11 cells treated with the combination of AZA and GL-V9, compared to the single drug ( Fig. 1A&B). CalcuSyn analysis showed a strong synergistic effect for the combination ( Fig. 1A&B). Similar results were also found in primary AML cells derived from 2 AML patients [patient 1 exhibited t(6;11) (q27;q23) chromosomal translocation, while Patient 2 presented with secondary AML, transformed from CMML (Chronic Myelomonocytic Leukemia) and featured ASXL1 and SRSF2 mutations] ( Fig. 1C&D). Moreover, AZA plus GL-V9 induced a substantial increase in cell apoptosis in U937 and MV4-11 cells compared to the single drug ( Fig. 1E&F). Consistently, the AZA+GL-V9 combination led to a notable increase in the protein level of Bax, BAD, BIM, and a decrease in BCL2 ( Fig. 1G). These data indicated the combination of AZA with GL-V9 has synergistic anti-leukemia effects in AML. To understand the underlying mechanisms of this synergy, we performed RNA-seq analysis in U937 cells, identifying 1385 and 586 DEGs (|log 2FC|≥2.0, P<0.05) upon AZA or GL-V9 treatment, respectively ( Fig. 2A). The mTOR signaling pathway exhibits prominent enrichment in the KEGG analysis of the overlapping DEGs between AZA and GL-V9 ( Fig. 2B). DDIT4, a negative regulator of mTOR emerged as one of the top DEGs in response to both AZA and GL-V9 treatment. Importantly, the AZA+GL-V9 treatment exhibited a higher expression level of DDIT4 compared to either drug alone and suppressed the phosphorylation of mTOR ( Fig. 2C). Additionally, the DDIT4 expression level was significantly decreased in AML patients, which derived from a public database (TCGA-AML, GSE13159)] ( Fig. 2D) and Zhongda Hospital (Nanjing, China) compared to the healthy controls ( Fig. 2E). To be noticed, high DDIT4 expression was associated with extended overall survival (P=0.021) ( Fig. 2F) and relapse-free survival (P=0.015) ( Fig. 2G), indicating DDIT4 may act as a tumor suppressor in AML. These findings suggested that the combination may exert the anti-leukemia effect by targeting the DDIT4/mTOR signaling pathway, as summarized in Fig. 2H. Conclusions Our study provides novel evidence of the synergistic effect on cell growth arrest and apoptosis treated with a new nature compound derived from wogonin combined with AZA in AML. Furthermore, we identified the mechanism underlying the synergy through targeting of DDIT4/mTOR signaling. These results offer preliminary support for the potential application of this combination therapy in treating AML patients.

Venetoclax-Based Therapy before Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia

Introduction The BCL-2 inhibitor venetoclax (VEN) is effective in older patients with untreated acute myeloid leukemia (AML). Few reports exist on the use of VEN as a bridging therapy for allogeneic hematopoietic cell transplantation (HCT) for AML. Previous studies have shown that NPM1 and IDH2 gene mutations are associated with high response rates to VEN therapy. We performed a retrospective cohort study to analyze the efficacy of VEN-based bridging therapy before HCT. Methods We included 46 patients who were eligible for HCT and received bridging therapy combined with VEN between April 2021 and June 2023 at our center. We evaluated response rates to VEN and HCT outcomes. None of the patients received VEN prior to the study. The response rate to VEN was evaluated using the 2022 European LeukemiaNet (ELN) criteria. We estimated overall survival (OS) using the Kaplan-Meier method, log-rank test, and Gray's test for univariate analysis of cumulative incidence of relapse (CIR) and non-relapse mortality (NRM). We used the Cox proportional hazards model for a multivariate analysis of OS. We extracted DNA from the bone marrow or peripheral blood, and analyzed gene mutations using next-generation sequencing (NGS), targeting 70 genes known to be recurrently mutated in myeloid malignancies. Results Of the 46 patients, 32 had de novo AML, 7 had de novo MDS/AML, 5 had secondary AML, 1 had secondary MDS/AML, and 1 had myeloid sarcoma. The median age was 59 (21-70) years. Nineteen were women and 7 had a history of HCT. The regimens combined with VEN were azacitidine in 39 cases and low-dose cytarabine in 7. According to the 2022 ELN risk classification by genetics at diagnosis, 7 were favorable, 11 were intermediate, and 27 were at adverse risk. Nine patients were in hematological complete remission (CR) / CR with incomplete count recovery (CRi) while 37 were not, when VEN was initiated. The maximum response rates among the patients who started VEN treatment in the non-CR group were: 18 with CR/CRi (49%) and no response in 19 (51%). The median time from the first dose of VEN to HCT was 70 (27-315) days. Forty-one patients underwent HCT and 19 (43%) were in CR/CRi at HCT. The reasons for discontinuation of VEN were HCT in 34 cases, failure in 9, and adverse events in 4 (hematological toxicity in 3 cases and infection in 1). Sixteen patients died due to primary disease (n=9), infection (n=5), thrombotic microangiopathy (n=1), and multi-organ failure (n=1). The median post-HCT observation period of survivors was 156 (25-775) days, and at 1-year after HCT, OS was 49.6% (95% CI: 28.0-67.9), CIR was 40.6% (95% CI: 24.1-56.6) and NRM was 15.2% (95% CI: 5.5-29.5). At 1-year after HCT, outcomes of the patients who were in CR/CRi at HCT was better than that of those who were not (OS, 80.8% vs. 26.4%, p=0.002; CIR, 13.4% vs. 61.8%, p<0.01; NRM, 0% vs. 26.7%, p<0.05). In 35 of the patients who underwent the first HCT, the 1-year OS was 88.9% in those who were in CR and 36.5% in those who were not (p=0.015). Thirty cases were non-CR at the start of the VEN regimen prior to their first HCT. This group had a 1-year OS of 57.8% (95% CI, 27.4-79.3). In 11 patients who achieved CR before HCT and 18 others who did not, the 1-year OS rates were 83.3% and 39.9%, respectively (p=0.10). Genetic analysis was performed by NGS in 37 patients before starting VEN, revealing mutations in TP53 (n=9), RUNX1 (n=7), IDH1 (n=6), ASXL1 (n=6), and DNMT3A (n=6) (Fig. 1A). Alterations in MDS-related genes (n=20) and kinase-related genes ( KIT, PTPN11, FLT3, KRAS, n=11) were frequent. Among the patients receiving their first HCTs, the 1-year OS was 0% in the group with TP53 mutations, and 63.9% in the wild-type TP53 group (p=0.04). The OS was worse in patients with mutated TP53 or kinase-related genes (n=19) than those without either mutation (n=15) (Fig. 1B, 1-year OS 28.7% vs. 72.9%, p=0.029). A multivariate analysis of OS revealed that patients who were not in CR at HCT (HR, 25.01 [95% CI, 2.406-259.9], p=0.007), those who previously underwent HCT (HR, 36.81 [95% CI, 4.599-294.7], p=0.035), and those with TP53 or kinase-related gene mutations (HR, 6.311 [95% CI, 1.137-350.0], p=0.035) had significantly lower OS rates. There was no significant difference in OS between the different ELN risk categories. Conclusions Non-CR at the time of HCT, a history of HCT, and mutations in TP53 or kinase-related genes were found to be independent poor prognostic factors for OS after VEN-based bridging treatment followed by HCT.

A Phase 1 Study of CD38-Bispecific Antibody (XmAb18968) for Patients with CD38 Expressing Relapsed/Refractory Acute Myeloid Leukemia

Background: Outcomes of adults with relapsed/refractory acute myeloid leukemia (RR-AML) have remained poor. CD38 is a transmembrane glycoprotein that is highly expressed in AML and is potentially targetable with CD38 blocking agents [Naik J et al. Haematologica 2019, Tembhare et al. J Immunother Cancer 2020]. XmAb18968 is a novel CD38-CD3 bi-specific T-cell engager with Fc domain modified to minimize Fcγ receptor binding and non-selective T-cell activation resulting in reduced cytokine release without compromising target cell killing. We designed a phase I clinical trial to assess the safety and tolerability of XmAb18968 in patients with RR-AML. Methods: We conducted a multicenter, open label, phase I dose escalation study of XmAb18968 (NCT05038644). Patients aged ≥18 years with relapsed/refractory AML, ECOG PS 0-2 and adequate organ function were eligible. Major exclusion criteria are hematopoietic cell transplantation within 6 months of enrollment, active acute graft-versus-host disease, and acute promyelocytic leukemia. Dose escalation was conducted using 3+3 design and 4 separate dose levels were studied [0.8mg, 1mg, 1.3mg, 1.5mg]. XmAb18968 was administered intravenously on days 1, 8, 15, 22 on a 28-day cycle. During cycle 1 alone, day 1 dose was fractionated and administered over 2 days to minimize the risk of significant cytokine release syndrome (CRS). Treatment was continued until progression or unacceptable toxicity. The primary objective was to determine the safety and dose limiting toxicity (DLT) and secondary objective was to determine the preliminary efficacy. Measurable residual disease (MRD) status was assessed using multicolor flow cytometry with 0.01% sensitivity. Correlative studies included pharmacokinetics, characterizing changes in serum cytokines and phenotypic expression of activated T-cells and leukemic cells, correlation of the phenotypic expression with changes in transcriptome at the single-cell level, proteomics evaluation of cytokine secretion at the single-cell level and correlation of response with N-glycan profiling, quantitative site-occupancy, and direct glycopeptide analysis. Results: Thirteen patients with RR-AML were enrolled, 12 of whom were evaluable (1 patient came off study before DLT period). Median age was 63 years (45-77), 77% with adverse risk disease, 38% with secondary AML, and received median two (range 2-7) prior lines of therapy. Twelve of 13 patients (92%) were previously treated with venetoclax based regimen and 31% had prior allogeneic HCT. Adverse risk mutations included TP53 (31%), RUNX1 (23%), and ASXL1 (15%). Grade 3 or higher adverse events included anemia (8%), neutropenia (15%), and thrombocytopenia (23%) (Table 1). CRS grades 1-2 were noted in 62% of patients, no grade ≥3 CRS or neurotoxicity (any grade) was seen. There was no dose limiting toxicity (DLT). Of the 12 evaluable total patients, clinically meaningful response was noted in two patients who were MRD positive by flow cytometry prior to study entry and achieved MRD negative CR (Table 2). These two patients who achieved MRD negative CR subsequently proceeded to allogeneic HCT. Median time to response was 1 cycle. Median OS of the cohort was 6.2 months (1.8-NR). Conclusions: XmAb18968 is safe and well tolerated in patients with RR-AML. Dose escalation yielded MRD negative CR in RR-AML patients who were MRD positive at study entry. Details on correlative studies examining mechanisms of therapeutic efficacy and resistance will be reported in the main meeting.

Real World Outcomes of CPX-351 Compared to Traditional Chemotherapy with Cytarabine Consolidation for Treatment of Secondary Acute Myeloid Leukemia

Introduction: Outcomes in patients with secondary AML (sAML) are inferior to those with de novo AML which has led investigators to seek alternatives to traditional treatment. Liposomal daunorubicin and cytarabine, or CPX-351, for the treatment of sAML has shown superior complete remission/complete remission with incomplete count recovery (CR/CRi), event-free survival (EFS), and overall survival (OS) compared to the traditional non-liposomal formulations of daunorubicin and cytarabine (“7+3”). However, this agent was originally studied in combination with a suboptimal consolidation regimen which did not include standard of care high dose cytarabine (HiDAC). This is often cited as a limitation of the study and may have contributed to the significantly lower response rates reported when compared to historical data. Here we present a real-world comparison of the efficacy and safety of patients with sAML receiving CPX-351 versus traditional 7+3 with HiDAC consolidation. Methods: Patients were at least 18 years of age with sAML, defined as: t-AML, AML-with Myelodysplasia-Related Changes (MRC), or AML with a history of chronic myelomonocytic leukemia (CMML). Patients were included if they had received induction (and consolidation, if applicable) with CPX-351 or induction with 7+3 (daunorubicin 60 mg/m 2 for 3 days and cytarabine 100 mg/m 2 for 7 days), followed by consolidation with cytarabine (≥1000 mg/m 2 x 6 doses). Nominal data were analyzed using chi squared tests or Fisher's exact tests. Continuous data were analyzed using the Mann-Whitney U test. A Kaplan Meier estimator was used for survival outcomes. Results: Overall, 58 patients with sAML were included, with 36 (62%) receiving CPX-351 and 22 (38%) receiving 7+3 followed by cytarabine-based consolidation between April 2013 and June 2022. Patients in the CPX-351 were older (67.5 vs 62 years, p=0.04) and had a higher prevalence of poor-risk cytogenetics (p=0.22). Other baseline characteristics were similar (Table 1). The rate of CR/CRi following induction was significantly higher in patients who received 7+3-based induction vs patients who received CPX-351 (81.8% vs 44.4%, p=0.01). Twenty-five percent of patients achieved CR/CRi in the CPX-351 arm with one induction cycle, compared to 95.5% in the 7+3 group. Median progression-free survival (PFS) was 3 vs 6.1 months (p=0.67) and median OS was 18.3 vs 9.3 months (p=0.73) in the CPX-351 and 7+3 cohorts, respectively (Figure 1). Thirty-nine percent of patients in the 7+3 cohort proceeded to allogeneic stem cell transplant compared to 81% in the CPX-351 cohort, however median OS in patients who underwent transplant was similar between the two cohorts (16.8 vs 15.8 months). Median OS was longer in the CPX-351 cohort however this was not statistically significant (Figure 1). Rates of both febrile neutropenia (94.3% vs 95.5%; P>0.99) and confirmed infections (54.3% vs 50%) were similar amongst those treated with CPX-351 and 7+3. Bacteremia and pneumonia were the most common infections in both cohorts. Median duration of neutropenia was significantly longer in the CPX-351 cohort (43 days vs. 27 days, p=0.002) with no major difference in duration of thrombocytopenia. In the 7+3 cohort, 11 deaths were directly attributed to progression, while 5 were associated with infection. In the CPX-351 cohort, 6 deaths were directly attributed to progression, while 8 were attributed to infection. At day 60, two deaths were observed in the CPX-351 cohort and there were no deaths in the 7+3 cohort. Conclusion: These findings suggest use of traditional 7+3 induction followed by HiDAC consolidation may be an alternative to CPX-351 for patients with sAML. Although median PFS was longer in the 7+3 cohort, this did not translate into longer median OS, likely due to the low rate of patients proceeding to transplant. Similar rates of overall survival in patients undergoing allogeneic stem cell transplantation support the hypothesis that transplant should be the goal for most patients with sAML. The retrospective nature of the study may limit broader application of this data.

STAG2 and PHF6: Comparison of 2 X-Linked Gene Mutations in Myeloid Neoplasms

INTRODUCTION: The Stromal Antigen 2 ( STAG2), on Xq25, is the most common cohesin complex gene mutated in myeloid neoplasms (MN) (5-10%). STAG2 mutations ( STAG2m) were incorporated in the ELN2022 as AML-MDS defining genetic mutations inferring poor prognosis and is a genetic marker in IPSS-M risk stratification. The PHD-finger protein 6 ( PHF6) gene, on Xq26.3, is a tumor suppressor gene, mutated in 3% of MN, and is more common in T-ALL. PHF6m is believed to be a late event in MN with little data on its prognostic implications in MN. Both STAG2m and PHF6m are more prevalent in males, but their implications on the clinical presentation of MN have not been compared prior. METHOD: Our study is a multicenter study at Mayo Clinic (Rochester, Florida, Arizona). After IRB approval, we retrospectively analyzed charts of 7935 patients who had NGS between 2016-2022. STAG2m was found in 96 patients, and PHF6m in 116 (including 3 with concurrent STAG2m and PHF6m). We excluded 4 PHF6m patients who had T-ALL. Data was captured at time of NGS. MDS risk stratification was by IPSS-M and AML by ELN2022. Overall survival (OS) was calculated from date of NGS to date of last follow-up. BlueSky Software was used for statistical analysis. RESULTS: Characteristics: We compared 96 STAG2m vs 112 PHF6m MN patients. Of STAG2m cases, 78% were male vs 76% in PHF6m MN. Median age was 72 vs 73 years, respectively. Diagnoses included AML (29% of STAG2m vs 34% of PHF6m MN), MDS (54% vs 28%), MDS/MPN (10% vs 21%) and MPN (3% vs 9%). MDS was more common among STAG2m MN (p<.001) while MDS/MPN was more common among PHF6m MN (=.05). MDS-IB was the most common subtype in both (69% vs 52% in STAG2m vs PHF6m MDS). MDS-LB and 5q subtypes were only found in PHF6m MDS, and there was more PHF6m MDS-RS (13% vs 2%). Median IPSS-M score was 0.9 vs 0.8 in STAG2m vs PHF6m MDS (both high-risk). Majority of STAG2m AML were adverse risk (96%) while PHF6m AML were intermediate (79%) (p<.001). AML cases included 43% vs 30% secondary AML (sAML) in STAG2m vs PHF6m AML. Among STAG2m and PHF6m MN, 17% of each were tMN. Cytogenetic abnormalities were more common in PHF6m MN (50% vs 31%, p=.005). The median bone marrow (BM) blasts count among STAG2m MN was 7% vs 4% in PHF6m MN (p=.03). Genetic characteristics: STAG2m were nonsense, frameshift and splice site (54%, 36% and 11%). PHF6m were nonsense, frameshift, splice site, missense and start loss variant mutations (44%, 33%, 12%, 10% and 1%). The median variant allele frequency (VAF) of STAG2m MN was 50% compared to 32% in PHF6m MN (p=.008). Co-mutations: The median number of co-mutations was 3 in STAG2m and 4 in PHF6m MN (p=.04). The most common were TET2m (37% in STAG2m MN vs 45% in PHF6m MN), RUNX1m (31% in both), SRSF2m (39% vs 20%), ASXL1m (66% vs 38%), BCORm (19% vs 6%), U2AF1m (13% vs 14%) and IDH2m (18% vs 7%). ASXL1m, SRSF2m, BCORm, IDH2m and SF3B1m were more common among STAG2m MN (p=<.001, .003, .006, .02, .09). JAK2m, IDH1m are more common among PHF6m MN (p=.02, .06). Survival: Of STAG2m and PHF6m MN, 70% and 72% of patients received treatment. HSCT was performed in 23 (24%) and 23 (21%) of STAG2m and PHF6m patients, including AML (n=9, n=10), MDS (n=12, n=8), MDS/MPN (n=2, n=2). OS among STAG2m and PHF6m MN was 20.5 and 22.1 months, respectively. OS among AML cases was 13.5 vs 21 months (p=.6) in STAG2m vs PHF6m, was NR vs 22 months (p=.4) in MDS, 11.7 vs 17.6 months in MDS/MPN (p=.4), and 10.4 vs 27.4 months (p=.5) in MPN. There was no difference between males and females in either STAG2m or PHF6m MN. HSCT led to longer OS among both STAG2m (NR vs 19.9 months, p=.01) and PHF6m MN patients (NR vs 17.6 months, p=.07). Among AML patients, HSCT did not significantly impact OS (18 vs 9.6 months, p=.3 and 25.1 vs 21 months, p=.2, in STAG2m and PHF6m). HSCT improved OS in STAG2m MDS (NR vs 20.5 months, p=.03). In PHF6m MDS, OS was 22.1 vs 13.1 months in HSCT vs non-HSCT (p=.3). CONCLUSION: STAG2m and PHF6m are 2 X-linked mutations that occur in MN. Both commonly occur in elderly males. MDS was the most common diagnosis in STAG2m MN. STAG2m co-occurred particularly with SRSF2m ASXL1m and BCORm, which are associated with poor prognosis. In our cohort, STAG2m AML carried a poorer prognosis than PHF6m AML. Our study confirms the ELN2022 AML risk stratification. MDS risk classification and OS did not differ between STAG2m and PHF6m in our cohort. A larger cohort is required to confirm our findings and may provide stronger validation.

Methylation Biology of a Blood-Based MDS Risk Stratification Test

Background: Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid malignancies associated with a myriad of deleterious outcomes and a 5-year relative survival of 37%. MDS risk stratification is key for optimal treatment decisions. We previously demonstrated that methylation-based markers may help stratify MDS risk and achieved comparable performance relative to IPSS-R (the Revised International Prognostic Scoring System) by assessing the risk prediction ability of a classifier trained with features from either Bone Marrow (BM) whole-genome bisulfite sequencing (WGBS) or serum targeted methylation (TM) sequencing. Here, we elucidate the biological underpinnings of the methylation-based classifier and explore the survival stratification performance of our previously reported classifier. Methods: Utilizing datasets from BM WGBS and matched Serum TM sequencing of 127 patients with MDS (N=104) and secondary AML (N=23), we delineated the features used by the classifier by identifying differentially methylated regions (DMRs) that distinguished patients with overall survival of >3 years from those with <3 years. Our approach also included a functional enrichment and driver gene analysis associated with these DMRs, as well as cluster analysis across patients. We performed further evaluations of the survival outcomes of our BM WGBS and matched Serum TM prognostic classifier using concordance indices and log-rank tests. Results: Our analysis revealed 7,742 DMRs in BM WGBS and 14,093 DMRs in the Serum TM that significantly separated the long and short-term survival groups. Unsupervised hierarchical clustering of differential methylation patterns in both BM WGBS and Serum TM highlighted three distinctive subgroups of samples: short-term survivors, long-term survivors, and a group with intermediate survival outcomes. Notably, the short-term survivor group exhibited extensive hypermethylation across a majority of DMRs, which were linked to key biological pathways including calcium signaling, cAMP, MAPK, Rap1, and PI3K-Akt. Enrichment analysis of the BM WGBS DMRs between individuals with <3 and >3 years of survival underscored the differential hypermethylation of promoters, CpG islands, and CpG shores in association with worse survival outcomes. Our analysis of BM WGBS DMR driver genes via Hypergeometric Optimization of Motif EnRichment (HOMER) revealed potential contributors to differential survival outcomes, including known genes associated with MDS/AML, such as EWS/FLI-1, ERG, Pu.1, and RUNX1. Both pathway and driver gene analysis recapitulated previously known drivers of MDS to AML progression. The methylation classifier achieved comparable risk stratification performance for both BM WGBS comparing with IPSS-R (C-index: 0.69 [95% CI: 0.61-0.77] for methylation vs 0.71 [95% CI: 0.64-0.77] for IPSS-R) and Serum TM (C-index: 0.68 [95% CI: 0.60-0.75] for methylation vs. 0.70 [95% CI: 0.63-0.78] for IPSS-R). At a specificity threshold of 0.8, both BM WGBS and Serum TM prognostic classifiers were able to stratify between predicted short and predicted long survivors (BM WGBS HR: 2.83, p<0.0001; Serum TM HR: 3.01, p=0.0008). Conclusions: Our findings generated biological insights into the methylation-based risk stratification of MDS, shedding light on the specific genomic features and biological pathways that underlie these methylation patterns. We also demonstrated that methylation-based MDS risk stratification performs comparably with IPSS-R. These insights not only expand our understanding of the complexity of MDS, but also reinforce the potential of methylation-based sequencing as a viable, possibly less-invasive, alternative for MDS risk stratification compared to traditional IPSS-R methods.

Daunorubicin/Cytarabine Liposome +/- Gemtuzumab Ozogamicin for Adult Patients with Newly Diagnosed, Low-Intermediate Risk, FLT3-Wild Type, AML: A Pilot Study

Introduction: Liposomal-encapsulated cytarabine and daunorubicin (CPX-351 or Vyxeos) has been approved by the Food and Drug Administration (FDA) for use in the treatment of newly diagnosed therapy-related AML (tAML) and AML with myelodysplasia-related changes (AML-MRCs). This was based on results of a phase III study conducted in patients with secondary AML (Lancet JE et al. JCO 2018). Despite data that highlighted the advantage of CPX-351 for sAML, it is intuitively likely that this powerful drug is also suitable for non-sAML. The mechanism of action is applicable for every AML. The aim of this study is to evaluate the role of CPX-351 for patients with de novo low/ intermediate risk, FLT3-negative AML. While a definitive phase III study is planned, herein is described the pilot forerunner study. Methods: This pilot multi-center study is planned to recruit 20 patients, ages 18-70 years, with low-intermediate risk FLT3-negative AML. Induction therapy is with CPX-351 on days 1,3,5. One dose of gemtuzumab ozogamicin (GO) can be added on day 1, at the discretion of the treating physician. Re-induction with CPX-351 on day 1,3 is permitted based on the results of day 14 bone marrow examination and at the discretion of the treating physician. Post-induction therapy followed the practice of the participating institutions. The primary endpoint was response rate. A key secondary endpoint was MRD evaluation, after induction, by multi-parameter flow cytometry with a threshold of 0.1%. As the initial genetic evaluation at diagnosis takes time, it was assumed upfront that an adverse risk may only become apparent in some patients with AML after initiation of therapy. Such subjects would ultimately be excluded from the study analysis. Results: Between August 2022 and June 2023, 20 patients were recruited and received the CPX-351 but 4 were finally diagnosed as high-risk and were excluded. The median age of the 15 patients that were included in the analysis was 56 years (range: 21-70), 53.3% were females. Eight of 15 patients (53.3%) were categorized as intermediate risk, according to the 2016 ELN guidelines, and 46.6% as favorable. Four patients (26.6%) received GO in addition to the CPX-351. None of the patients needed to receive re-induction. 100% of the patients achieved CR. Five of 13 evaluable patients (38.4%) achieved MRD-negativity post induction. No unfamiliar or severe adverse events were reported, even among patients who received GO. One patient died from sepsis after hematopoietic stem cell transplant. The median time from day 1 of treatment to neutrophil recovery (ANC≥500/µL) and platelet recovery (≥50,000/µL) was 29 and 24 days, respectively, for the entire cohort and 27 and 24 days, respectively, for those who also received GO. Discussion: The hallmark of this study is reflected by the focus on patients with the low and intermediate-risk AML and not tAML and AML-MRCs, as was approved by the FDA. It includes also young patients (≥18 years), and not only those≥ 60 years. In addition, the CPX-351 was only given as induction therapy (with an option for re-induction) but not after achieving CR. The combination of CPX-351 with GO, although not previously reported, was based on current practice of adding GO to standard induction in some patients, allowing for a realistic future true comparator with standard 7+3 induction. In addition, MRD assessment post induction with CPX-351 has not been previously reported. The CR rate was 100% and the MRD results were a basis for subsequent studies. Finally, this is a pilot study that precedes a definitive planned phase III study that will compare standard induction with 7+3 versus CPX-351, with post-induction MRD monitoring and GO optional in both arms. Such a study may ultimately lead to a paradigm shift in the initial induction therapy of non-adverse risk patients with AML.

Stratification Using ECOG, ADL and HCT-CI Scales, but Not CGA Enables Identifying Elderly AML Patients Fit for Intensive Chemotherapy - a Multicenter Study from Polish Adult Leukemia Group

Introduction: A key part of decision-making in older AML patients is an insightful clinical assessment before qualification for treatment with intensive chemotherapy (IC). It was demonstrated that among the patients initially deemed “fit” for IC, there are vulnerable patients who experience greater treatment toxicity and have poorer outcomes. Comprehensive geriatric assessment (CGA) is a well-recognized tool for identifying such patients. However, due to its time-consuming nature, it is not commonly used. A number of other prognostic models exist, but none of them enable fast and optimal identification of patients eligible for IC. Aim: In this prospective observational study our group aimed to I) assess clinical outcomes of elderly AML patients who were stratified by Eastern Cooperative Oncology Group Performance Status (ECOG PS), Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI), Activity of Daily Living (ADL) scales and received IC and II) evaluate the predictive and prognostic value of CGA components. Material and methods: AML patients aged between 60 and 75 were considered fit for IC if they met all 3 stratification criteria: ECOG PS<2 and HCT-CI<3 and ADL=6. IC regimens included daunorubicin and cytarabine (DA) or daunorubicin, cytarabine and cladribine (DAC) followed by 2 consolidation cycles according to local references. CGA was performed by a qualified medical professional before treatment initiation. CGA included Instrumental Activities of Daily Living Score (iADL), timed up and go test (TUG), geriatric depression scale (GDS), Mini-mental scale Examination (MMSE) and Mini Nutritional Assessment (MNA). The correlations between CGA and complete response (CR) rate were determined by Chi-square test or Fisher's exact test. The Kaplan-Meier analysis and log-rank test were used to compare relapse-free survival (RFS) and overall survival (OS) Results: In total, 85 patients with a median age of 65 years [IQR:63.5-69.0] and slight male predominance (53%) were included in the study. Most patients had HCT-CI score <2 (71.8%). Secondary AML was diagnosed in 23.5% of patients, and most patients had intermediate (32.9%) or adverse (37.6%) ELN cytogenetic risk. Fifty-five (58.8%) patients achieved CR after induction. Median OS reached 16.0 months [95% CI: 11.0-21.00] with median RFS 15.3 months [95% CI: 12.1-18.4]. No significant difference in CR rate (p=0.451), OS (p=0.484) or RFS (p=0.529) was demonstrated between DA or DAC groups. Regardless of induction regimen, patients with CR presented significantly improved OS (p=0.015 for DA, p=0.029 for DAC) compared with non-CR patients. None of the CGA components was shown to influence the CR rate, OS or RFS. Conclusions: In patients aged 60-70 years with AML, stratification by ECOG, ADL, and HCT-CI is an effective tool for qualifying patients for intensive chemotherapy. Comprehensive geriatric assessment does not improve identification of vulnerable patients in this group.

The Cytogenetic and Molecular Testing Landscape in Patients with Newly Diagnosed Acute Myeloid Leukemia in Routine Clinical Practices in the United States

Background: The prognostic and treatment (Tx) landscape for newly diagnosed acute myeloid leukemia (ND AML) has evolved in recent years; several novel therapies have been recommended in Tx guidelines. Tx for patients (pts) with actionable IDH1, IDH2, or FLT3 mutations includes Venetoclax (Ven)-based regimens (i.e. Ven+hypomethylating agents [HMAs] and Ven+low-dose cytarabine), HMA monotherapy (i.e. Azacitidine [Aza] or decitabine), and targeted Tx (i.e. ivosidenib±Aza, enasidenib±Aza, sorafenib±HMAs, and gilteritinib+Aza). This study aims to better understand the cytogenetic and molecular testing landscape among pts with ND AML receiving first-line (1L) Tx in routine clinical settings in the United States (US). Methods: This retrospective cohort study used data from the Flatiron Health database: a US nationwide, electronic health record-derived de-identified database. Pts with ND AML, aged ≥18 years, diagnosed with AML between January 1, 2020, and December 31, 2022, with ≥2 visits recorded within 3 months of AML diagnosis (Dx), and 1L Tx initiated any time after AML Dx were included.Pts with secondary AML, acute promyelocytic leukemia or t(9;22) were excluded. Descriptive analyses evaluated the cytogenetic testing pattern, molecular testing pattern (including next generation sequencing [NGS] and polymerase chain reaction [PCR]), and 1L Tx pattern for pts harboring IDH1/2 or FLT3 mutations (categorized as Ven-based, HMA monotherapy, and targeted Tx). Results: A total of 1577 pts met the study criteria. Overall, 95% (n=1501) of pts received a cytogenetic test and 91% (n=1434) received molecular testing that corresponded to a positive or negative result from the first specimen collected. Of the pts with molecular testing, 70% (n=1005) were treated in the community setting, 27% (n=390) in the academic setting, and 3% (n=39) in both academic and community settings. NGS was the most used molecular testing technique in all settings (76%, 50%, and 61% in the community setting, academic setting, and both settings, respectively) vs PCR (11%, 34%, and 26%, respectively). Testing rates were relatively consistent from 2020 to 2022 ( Figure). Bone marrow aspirate alone was the most common specimen type used for molecular testing (82%, 65% and 72%, in the community setting, academic setting, and both settings, respectively), followed by blood only (14%, 25%, and 21%, respectively). A total of 78% of pts treated in the community setting had their first specimen collected at AML Dx for molecular testing (vs 63% in the academic setting and 59% in both settings). Overall, 85% of pts treated in the community setting had their first specimen collected for molecular testing before 1L Tx initiation (vs 75% in the academic setting and 90% in both settings), and 35% had repeated molecular testing (proxy by second specimen collected) after 2 weeks of 1L Tx initiation (vs 40% in the academic setting and 29% in both settings). Of the pts who received molecular testing, 25% (n=365) harbored IDH1/2 or FLT3 mutations. A total of 39% (n=142) of pts with IDH1/2 or FLT3 mutations received Ven-based Tx, 9% (n=34) received HMA monotherapy, 3% (n=12) received targeted Tx, and 49% (n=177) received chemotherapy excluding HMAs. Conclusions: This study found that cytogenetic and molecular testing have been integrated into routine clinical care settings for pts with ND AML receiving 1L Tx. The consistent testing rates in recent years, common use of NGS molecular testing technique, and the majority of pts having first specimen collected for molecular testing prior to 1L Tx initiation reflect physicians' intention to leverage molecular data to better inform Tx decisions. The subset of pts with second specimen collected for molecular testing after 2 weeks of 1L Tx initiation suggests some physicians' efforts to evaluate new and/or persistent targeted stable mutations. Although the rate of molecular testing was high, nearly half of pts harboring IDH1/2 or FLT3 mutations received Tx guideline recommended regimens, and Ven-based Tx was more commonly administered than HMA monotherapy or targeted Tx; suggesting physicians are more commonly choosing a mutation agnostic Tx approach in ND AML. Future studies are warranted to better understand potential barriers to the timely report of molecular testing results in routine clinical practice for pts with AML.

ABC Regimen (Azacitidine, Venetoclax and Chidamide) Is Comparable to the “3+7” Regimen in Newly Diagnosed AML: A Real-World Experience from South China

Background: Traditional “3+7” intense chemotherapy (IC) regimen is the standard treatment backbone for fitness patients with newly diagnosed AML. The azacitidine plus venetoclax (AB) regimen has recently been recommended for elderly AML patients or those ineligible for IC treatment. However, neither the “3+7” IC nor “AB” regimen unmet the needs ofadequate safety and effectiveness, especially on aspects of early death and some subtypes of leukemia, such as M5, or with RUNX1, FLT3-ITD, TP53 mutation, or with MCL-1 up-expression. Chidamide, a novel oral histone deacetylase inhibitor, can overcome the upregulating of MCL-1 expression induced by venetoclax, and synergy with azacitidine and venetoclax induces apoptosis of acute myeloid leukemia cells. Azacitidine-Venetoclax -Chidamide (ABC) combination regimen had been successfully used for refractory relapsed AML and newly diagnosed AML-M5 by Prof. Bin Xu and Prof. Shengli Xue, respectively. Whether the ABC regimen can be comparable to the “3+7” IC regimen in newly diagnosed AML induction therapy is still unknown. Aim: This pilot study aims to evaluate the efficacy and safety of the ABC regimen versus the “3+7” IC regimen in newly diagnosed AML. Method: A total of 112 patients with newly diagnosed AML (not APL) were enrolled in this study. Thirty-one patients from the ABC Collaboration Group were unfitness or unwilling to undergo IC therapy and received ABC regimen treatment from May 2022 to July 2023. Eighty-one patients from GDPH in the AML Collaboration Group of South China were treated with a “3+7” (IC) regimen between November 2010 and August 2013. Treatment protocol: The ABC-28d protocol consists of azacitidine 75mg/M 2, d1-7; venetoclax 100mg d1, 200mg d2, 400mg d3-28, and Chidamide 10mg, d1-6/week for 2 weeks, 28 days as one cycle. The ABC-14d regimen consists of azacitidine 75mg/M 2, d1-7; venetoclax 100mg d1, 200mg d2, 400mg d3-14, and Chidamide 5mg, d1-6/week for 2 weeks, 28 days as one cycle. “3+7” IC regimen consists of idarubicin 10mg/M 2, d1-3; cytarabine 100 mg/M 2, d1-7. Baseline characteristics for patients are listed in Table 1. We compared the complete response (CR) and overall response rate (ORR= CR+ CR with incomplete recovery of blood counts CRi + partial response PR) after the first course of treatment, cumulative response rate, and adverse events between these two cohorts. Results: The outcome data of the ABC regimen was updated as of July 2023 for a median follow-up of 78 days (range 28- 402) for the ABC cohort. The ORR and CR/CRi rate of the ABC cohort after the first cycle therapy was not significantly different from the IC cohort (80.6% vs 75.3%, P =0.108 and 71% vs 65.8%, P=0.552). And the cumulative response rate of the ABC cohort was 87.1%. In primary AML, the CR rate of patients in the ABC cohort was higher than the IC cohort (84% vs 65.8%, P=0.075). Of concern, all 12 patients with M4/M5 treated with the ABC regimen achieved CR (100% vs 76.2%, P=0.03). In secondary AML, the ABC regimen was also poor (CR/CRi rate 33.3%). The ABC regimen is not only applicable to the elder patients (CR rate 100%, 15/15) but also young patients(<60 Y) same as the IC regimen ( CR rate: 71.4% vs 65.8%, P=0.726). The response was summarized in Table 1 and Figure 1. Up to 30 July 2023, the ABC cohort has not reached the median remission duration and overall survival (OS). Grade 3 or 4 hematologic adverse events occurred in 81.2% of patients. Neutrophil and platelet median recovery times were 21 days(0-58) and 16 days (0-58), respectively. Patients in the ABC-14d cohort had lower rates of hematologic AEs than ABC-28d cohort (Neutrophil: 12.13±14.33 vs 26.33±16.89, P =0.024 and Platelet: 11.88±13.92 vs 24.58±18.59, P = 0.048). The most frequent non-hematologic AEs of any grade were neutropenic fever (n=15), pneumonia (n=8) and reversible nephrotoxicity (n=4). In the ABC cohort, no patient experienced early death at week 4 or 8. Conclusions: This preliminary study showed that the safety and efficacy of the ABC regimen were comparable to the traditional “3+7” regimen for newly diagnosed AML, even better for the subtype of AML-M4/M5. The ABC-14 days regimen showed comparable efficacy but better tolerability. However, whether the ABC regimen can replace the traditional intense chemotherapy needs to be confirmed by further randomized controlled trials.

Pivekimab Sunirine (PVEK, IMGN632), a CD123-Targeting Antibody-Drug Conjugate, in Combination with Azacitidine and Venetoclax in Patients with Newly Diagnosed Acute Myeloid Leukemia

Background In unfit patients (pts) with newly diagnosed (ND) AML, long-term survival remains short (mOS 14.7 months) despite improved responses (CR 37% and CR/CRi 66%) with azacitidine (AZA) and venetoclax (VEN) (VIALE-A, DiNardo NEJM 2020). In a pooled analysis of AZA-VEN in ND AML pts with poor risk cytogenetics the response rates were higher in TP53wt pts (CR/CRi 70%) compared with TP53mut pts (CR/CRi 41%) (Pollyea Clin Cancer Res 2022). The measurable residual disease (MRD)-negative rate was 41% in AZA-VEN treated pts in VIALE-A which was associated with improved survival (Pratz JCO 2022). Pivekimab sunirine (PVEK, IMGN632) is a first-in-class antibody-drug conjugate (ADC) comprising a high-affinity CD123 antibody, cleavable linker, and an indolinobenzodiazepine pseudodimer (IGN) payload. The novel IGN payload alkylates DNA and causes single strand breaks without crosslinking (Kovtun Blood Adv 2018). Methods This is an ongoing, open-label, multicenter, Phase 1b/2 study of PVEK in combination with AZA +VEN in adults with ND CD123-positive AML (any CD123+ expression by local flow cytometry or IHC). Pts received the recommended phase 2 dose of PVEK 0.045 mg/kg IV on D7 + AZA 75 mg/m 2 SC or IV daily on D1-7 + VEN up to 400 mg PO daily for 14 to 28 days (based on cohort assignment) in a 28-day cycle. Bone marrow assessment was performed at D14 (cohort 1) or D21 (cohort 2) of cycle 1 to determine VEN duration. The primary endpoints are composite CR rate (CCR [CR+CRh+CRp+CRi]), MRD rate (assessed centrally [Hematologics, Inc.] by flow cytometry; <0.1% defined as negative) and duration of remission. Key secondary endpoints are safety, pharmacokinetics and immunogenicity. Responses were determined using ELN 2017 criteria (with the addition of CRh) and a 14-day post-marrow count recovery window. Results As of July 17, 2023, data is available for 50 ND pts (n=25 per cohort) treated with PVEK+AZA+VEN and are aggregately reported here. The median age was 74 years (range, 46-83), 42% were ≥ 75 years old, 26% had secondary AML, 64% were ELN 2017 adverse risk, and 38% had a TP53mut. The most common non-hematologic treatment-emergent adverse events (TEAE) (all grades [grade 3+]) seen in > 20% of all pts were febrile neutropenia (44% [38%]), constipation (42% [2%]), peripheral edema (36% [4%]), diarrhea (36% [2%]), hypophosphatemia (32% [0%], nausea (28% [4%]), and hypokalemia (24% [2%]). No veno-occlusive disease (VOD) events were reported. In responders, the median time to achieve absolute neutrophil count ≥500/µL and platelet count ≥50,000/µL was 35.5 days (range, 20-55) and 22 days (range, 20-55), respectively. The median post-remission cycle delay (beyond cycle day 28) was 14 days. Two pts discontinued PVEK due to a TEAE (edema; marrow aplasia). The 60-day mortality was 4%. In the ITT population (N=50) the CR rate was 52% (26/50), and the CCR rate was 66% (33/50). In pts ≥ 75 years old, the CCR rate was 76% (16/21). In pts known to be TP53wt, both the CR and CCR rate was 88% (22/25). Additional response subsets in Table 1. Twenty-one pts received 9-14 days of VEN, 9 pts received 15-21 days of VEN and 20 pts received ≥ 22 days of VEN in cycle 1; of those who received ≤ 14 days of VEN the CR rate was 71% (15/21) and the CCR rate was 76% (16/21). Of the 26 pts who achieved CCR and had an MRD-evaluable sample, 73% (19/26) achieved MRD negativity (CCR MRD-, <0.1% residual blasts); notably all had undetectable MRD levels (lower level of detection is 0.02%). MRD-negativity was achieved rapidly with a median of 1.7 months (range, 0.8-4.5). CCR MRD- rates were high across major molecular subsets, including FLT3 (ITD/TKD) at 100% (7/7), IDH1/2 at 89% (8/9), and NPM1 at 89% (8/9), as well as ELN risk groups (intermediate 80% [8/10]; adverse 64% [9/14]). Conclusion With a manageable safety profile in pts with ND AML, the PVEK+AZA+VEN triplet demonstrated anti-leukemia activity with robust CR rates and early MRD negative responses in a cohort enriched for adverse disease characteristics (64% ELN adverse risk; 38% TP53mut). Encouraging CCR MRD- rates were observed across cytogenetic/molecular subsets, and the majority of responding pts achieved early and deep remissions, which may translate to improved clinical outcomes. The regimen was well tolerated with no new safety signals, and the addition of PVEK to the AZA-VEN backbone did not appear to meaningfully prolong count recovery.

Phase 2 Trial of Mini-Hyper-CVD Plus Inotuzumab Ozogamicin, with or without Blinatumomab, in Older Patients with Newly Diagnosed Philadelphia Chromosome-Negative B-Cell Acute Lymphoblastic Leukemia

Background The introduction of inotuzumab ozogamicin (InO) and blinatumomab (blina) has drastically improved the overall survival (OS) of patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). Older patients with B-ALL have worse outcomes compared with younger patients due to the poor-risk biology of their disease and their inability to tolerate intensive chemotherapy. We aim to study the incorporation of InO and blina with low intensity chemotherapy in older patients with newly diagnosed (ND) B-ALL. Methods Adults ≥60 years with ND Philadelphia chromosome (Ph)-negative B-ALL who were untreated or had received up to two cycles of previous therapy were eligible. Other inclusion criteria included an Eastern Cooperative Oncology Group (ECOG) performance status of ≤3 and adequate organ function. Patients with central nervous system (CNS) disease were eligible. Patients received mini-Hyper-CVD (mHCVD, cyclophosphamide 150mg/m 2 q12h D1-3, dexamethasone 20mg daily D1-4, 11-14, and vincristine 2mg D1, 8 alternating with methotrexate (MTX) 250mg/m 2 D1 & cytarabine 500mg/m 2 q12h D2, 3) for up to 8 cycles. Eight doses of intrathecal (IT) MTX /cytarabine were given for CNS prophylaxis; patients with CNS disease had IT hydrocortisone, MTX, and cytarabine twice weekly till CNS clearance, then weekly x4. Eight doses of rituximab 375mg/m 2 were given on D1, 8 of C1-4 if CD20 was ≥20% by flow cytometry. Initially, InO was given at 1.3-1.8mg/m 2 on D3 of C1 and 1.0-1.3mg/m 2 on D3 in C2-4. The protocol was amended from patient 50 such that InO was given in fractionated doses with a maximum cumulative dose of 2.7mg/m 2 (0.6 mg/m 2 on D2 of C1, 0.3 mg/m 2 on D8 of C1, then 0.3 mg/m 2 on D2 and D8 of C2-4). Ursodeoxycholic acid was given to all patients. Four cycles of blina 28µg/day replaced C5-8 of mHCVD + InO. Maintenance was initially with vincristine 2mg D1, prednisolone 50mg daily D1-5, 6-mercaptopurine 50mg BID & MTX 10mg/m 2 weekly (POMP) for three years. After the protocol amendment, this was reduced to 12 cycles of POMP, with one cycle of blina given after every three POMP cycles (total four blina cycles). Results 83 patients with a median age of 68y (range, 60 - 87; ≥70y, 34%) were enrolled (Table 1). Several patients had high-risk features: 25 (39%) harbored TP53 mutations, 9 (18%) had a Ph-like signature, and 19 (23%) had high-risk cytogenetics (12 low hypodiploidy/near triploidy, 3 tetraploidy, 3 complex and 1 t(4;11)). 77 patients were not in CR at enrollment and evaluable for response. 76 (99%) responded, with 69 (90%) attaining CR. Among responders, 60 (79%) and 71 (94%) patients had no detectable minimal residual disease (MRD) by flow cytometry after C1 and overall, respectively. No early deaths were observed. After a median follow-up of 88 months (IQR, 41-120), the median overall survival (OS) was 56 months (95%CI, 28-85), and the median progression-free survival (PFS) was 47 months (95% CI, 21-72). The 5-year continuous remission duration (CRD) and OS rates were 78% and 49%, respectively. The 5-year OS for patients aged 60-69 without adverse cytogenetics (n=40), age 60-69 with adverse cytogenetics (n=15), age ≥70 without adverse cytogenetics (n=24) and age ≥70 with adverse cytogenetics (n=4) were 73%, 27%, 39% and 0%, respectively. Five (6%) patients underwent allogeneic stem cell transplantation (ASCT) in first CR, 12 (15%) relapsed, 33 (40%) remain in ongoing continuous remission without ASCT, and 33 (40%) died in remission. Of the 12 relapsing patients, 5 had extramedullary disease, all with CNS involvement. 12 (14%) patients died due to progressive disease at a median of 23 (range 2 - 78) months; these patients had a median age of 64 (range 60 - 79) years. Of the 33 who died in remission, nine were due to secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). The median age of these patients was 71 years (range, 64 - 87), with a median time to MDS/AML of 34 months (range, 7 - 75). Fourteen deaths in CR were due to treatment-related complications (9 sepsis, 3 veno-occlusive disease (VOD), 2 ASCT). Six (7%) patients developed veno-occlusive disease, 4/49 (8%) in the pre-amendment group and 2/34 (6%) in the post-amendment group. Conclusion Older patients with ND Ph-negative ALL treated with mHCVD plus InO, with or without blina had excellent response rates and deep remissions. However, further adjustment of the regimen is needed, especially in patients ≥70 years.