Gemtuzumab Research Articles

Fractionated Gemtuzumab Ozogamicin Followed By Non-Engraftment Donor Leukocyte Infusions for Relapsed/Refractory Acute Myeloid Leukemia

Background: Previous studies have shown durable AML patient responses following donor lymphocyte infusions (DLI) in the absence of engraftment in both the frontline and relapsed setting (Dey et al, BJH 2005, Colvin et al, BBMT 2009, Ai et al, Blood 2010). Herein we report results from the completed dose-escalation phase from our trial of fractionated dosing of gemtuzumab ozogamicin (GO) followed by non-engraftment mismatched allogeneic donor cells infusion in patients with relapsed/refractory (R/R) AML. In this trial, instead of engraftment, it is postulated that donor cells serve as a potent immune stimulator. Study Design and Methods: In this phase I/II study, GO 6-9mg/m 2 total dose was administered as a fractionated 2-3mg/m 2 dose (capped at 4.5mg) on days 1, 4, and 7, followed by infusion of HLA-mismatched (0-3/6 antigens) related donor cells on day 8 [NCT03374332]. The dose-escalation phase 1 cohort used a 3+3 design combining GO with donor leucocyte infusion (DLI) at dose 1-2x10 7 CD3+ cells/kg (Dose Level 1) or 1-2x10 8 CD3+ cells/kg (Dose Level 2). Patients enrolled in the phase II portion were treated at the maximum tolerated dose (MTD) level. Lab correlative studies were drawn pre and post DLI to assess immune effector cells and leukemic blast surface expression as well as cytokine release profiles. Patients 18 years of age and older with histologically confirmed R/R AML who had recurrence or progression after at least 1 prior standard treatment were eligible. Enrollees must have had no active systemic infections and adequate lung, liver, cardiac, and renal function with an ECOG PS 0-1. Patients in CR or CRi after initial treatment could receive up to 2 additional treatments with GO+DLI. Results: Eleven patients (7 men and 4 women) were enrolled into the study. The median age was 72 years (54-81 years) and patients had received 1-4 previous lines of treatment. All patients were refractory to hypomethylating agents and venetoclax. No patient was a candidate for allogeneic stem cell transplant at the time of study enrollment. Ten patients received 3/6 and one patient received 1/6 HLA mismatched donor cells from a first- or second-degree relative. The MTD was determined to be 2x10 8 CD3+ cells/kg. Three patients were enrolled on dose level 1 and eight patients were enrolled on dose level 2. Treatment was well tolerated with minimal Grade 3 or 4 non-hematologic adverse events attributable to the study ( Table 1). One patient at dose level 2 developed septic shock and died prior to DLI while another patient at dose level 2 developed cryptococcal fungemia and died within one week of DLI. No donor experienced a Grade 3 or 4 adverse event. All patients had fever post DLI that fit criteria for Grade 1 or 2 CRS while one patient developed Grade 3 CR. Two patients with Grade 2 CRS and one patient with Grade 3 CRS received tociluzimab. One patient attained a CR after one cycle of GO+DLI. All other patients had progressive disease. Ultimately the study was stopped early due to futility. Median IL-6 and IL-8 levels were higher in the first 3 patients at dose level 2 (605.5pg/mL and 218.5 pg/mL) compared to the three patients in dose level 1 (79pg/mL and 57.8 pg/mL) but the difference was not statistically significant. IL-10 levels were significantly higher in dose level 2 than dose level 1(125 vs 14.8 pg/mL, p=0.05) Conclusions: The MTD of DLI in combination with GO for relapsed/refractory AML patients is 2x10 8 CD3+ cells/kg. Treatment in an older relapsed/refractory population was well tolerated. Patients reliably developed fevers post DLI with Grade1 or 2 CRS. However, there was no evidence that fever development corresponded to a clinical benefit or that the addition of non-engraftment DLI augmented the effect of single agent gemtuzumab. Additional analysis of cytokine release profiles for the remaining patients as well as immune checkpoint inhibition on leukemic blasts for all patients will be presented at the meeting.

Multicenter Retrospective Evaluation of Treatment of High-Risk Acute Promyelocytic Leukemia (APL): Results from the Hematology Research Outcomes (HERO) Consortium

Background: Regimens employing all-trans retinoid acid and arsenic (ATRA+ATO) are the backbone of high-risk APL treatment. The APML4 regimen consists of a three-phase treatment approach: induction with ATRA, ATO, and idarubicin; two cycles of consolidation with ATRA+ATO; and maintenance with ATRA, methotrexate, and mercaptopurine. 1 MD Anderson Cancer Center (MDACC) developed a regimen incorporating gemtuzumab ozogamicin (GO) in addition to ATRA+ATO. 2 Differences in tolerability and efficacy between these two approaches are unknown as no comparative data exists. We aimed to describe real-world treatment outcomes for high-risk APL, comparing toxicity between APML4 and ATRA+ATO+GO. Methods We conducted a multicenter, retrospective cohort study including patients treated among six US centers participating in the pharmacist-led collaborative research consortium, HERO. Adults (>18 years) with newly diagnosed high-risk APL (t(15;17)(q24.1;q21.2)) according to the Sanz risk model 3 between April 2014 and June 2022, who received at least one dose of an induction regimen under the institution's high-risk protocol were compared based on induction regimen received. Patients with incomplete records were excluded. The primary endpoint was a composite of mortality, ICU admission, or confirmed infection during induction. Secondary endpoints included individual components of the primary endpoint, other induction-related toxicities, and complete response (CR) rate after induction. Analyses were performed as intent-to-treat which included all patients who received APML4 and ATRA+ATO+GO inductions regardless of consolidation strategies. Chi-square or Fisher's exact tests were utilized to evaluate dichotomous variables. Continuous variables were analyzed via Student's t-test or Mann-Whitney U test. Kaplan-Meier analysis with log-rank test was performed to estimate progression-free survival (PFS) and overall survival (OS). Results Fifty-seven patients with high-risk APL who started either APML4 (n=41) or ATRA+ATO+GO (n=16) as induction treatment met inclusion criteria. Baseline characteristics were balanced (Table 1) except for race and ethnicity, with a higher percentage of non-Hispanic white patients in the APML4 cohort (p=0.020) and a higher percentage of Hispanic/LatinX in the ATRA+ATO+GO cohort (p=0.011). Of evaluated molecular abnormalities, FLT3-ITD was most common (76%). Steroid prophylaxis was more common in the ATRA+ATO+GO cohort (p=0.015). Additional cytoreductive therapy was frequent in both arms: hydroxyurea used more often in the APML4 cohort (p=0.033) and idarubicin in the ATRA+ATO+GO cohort (p<0.001) (Table 1). Induction mortality was 7%, including 3 deaths in the APML4 cohort and 1 in the ATRA+ATO+GO (Table 2; p=1.000). Time to platelet recovery was longer with APML4 than ATRA+ATO+GO (median 27 vs 23 days, p=0.021) as was time to ANC recovery (median 38 vs. 29 days, p=0.020). No additional significant differences in individual safety outcomes were observed. Of note, there was no difference in differentiation syndrome that required dose changes or holds between the two cohorts. There were no detectable differences in treatment effectiveness, with 92.7% of patients in the APML4 arm and 93.8% of patients in the ATRA+ATO/GO arm achieving a CR at end of induction (Table 2). With a median follow-up of 35 months, neither group reached the median for overall survival and the estimated 36-month survival was similar between cohorts; 92.5% (95%CI 84.3-100) for APML4 and 94.1% (95%CI 83.1-100) for ATRA+ATO+GO. Conclusion ATRA+ATO-based regimens yield similar short- and long-term efficacy in a high-risk APL population, though hematologic recovery occurred earlier in the ATRA+ATO+GO cohort. No clinically significant differences in acute toxicities exist between APML4 and ATRA+ATO+GO induction strategies as demonstrated by this real-world multicenter analysis.

Phase 1/2 Study of Donor-Derived Anti-CD33 Chimeric Antigen Receptor Expressing T Cells (VCAR33) in Patients with Relapsed or Refractory Acute Myeloid Leukemia after Allogeneic Hematopoietic Cell Transplantation

Background and Significance: Although allogeneic hematopoietic cell transplantation (alloHCT) is a potentially curative therapy for patients with high-risk acute myeloid leukemia (AML), relapse occurs in 30% to 40% of alloHCT recipients and is associated with a 2-year post-relapse survival rate of less than 20%. Chimeric antigen receptor (CAR) T cells targeting tumor-associated antigens have demonstrated efficacy in relapsed/refractory (R/R) acute lymphoblastic leukemia and other hematologic malignancies, but there is limited clinical experience with CAR T cell therapies for AML. Current challenges for autologous AML CAR T cell therapy include the inability to harvest adequate numbers of functional, undifferentiated T cells as CAR T cell starting material. In addition, the potential presence of AML blasts in an autologous cell collection can interfere with T cell proliferation and function during the manufacturing process. To circumvent these impediments in patients with R/R AML after alloHCT, VCAR33 represents a CD33-directed CAR T cell product generated from lymphocytes from each patient's prior allogeneic stem cell donor. CAR T cell manufacture from HLA-matched donors will likely not only eliminate delays and failures in production due to lymphopenia but also improve T cell function by using healthy starting material. CD33 is a preferential target for AML CAR T cell therapy as it is expressed on the majority (>80%) of AML blasts and because prior clinical experience with gemtuzumab ozogamicin (GO; tradename: Mylotarg TM) has demonstrated the safety and efficacy of targeting CD33. Study Design and Methods: Study NCTxxxxxxxx* is a multi-center phase 1/2 study evaluating the safety and preliminary efficacy of VCAR33, donor-derived allogeneic CAR T cells targeting CD33 (Figure 1). The CAR construct used for the manufacture of VCAR33 contains a lintuzumab-derived binding domain and a CD28 co-stimulatory domain. Key inclusion criteria include adult patients with relapsed or measurable residual disease positive (MRD+) AML after undergoing alloHCT with an 8/8 HLA-matched related or unrelated donor. Patients who have undergone alloHCT with trem-cel, a CD33-deleted allogeneic stem cell product intended to facilitate the post-HCT treatment with CD33-directed therapies by reducing on-target off-tumor hematotoxicity, may also participate. Patients will be assigned to one of two study arms based on their AML disease burden: Arm A for morphologic disease with ≥ 5% blasts in the bone marrow, or Arm B for MRD+ defined as < 5% blasts in the bone marrow with ≥ 0.1% CD33+ leukemia cells by flow cytometry. The patient's prior stem cell donor undergoes apheresis for collection of mononuclear cells, which are used as starting material for VCAR33 manufacturing. Patients will receive lymphodepletion on days -5 to -2 with fludarabine (total 120 mg/m 2) and cyclophosphamide (total 1000 mg/m 2) followed by infusion of VCAR33 on Day 0. Each study arm will enroll and escalate independently according to a standard 3+3 trial design, starting at 1 x 10 6 CAR T cells/kg for Dose Level 1. The dose limiting toxicity monitoring period is 28 days, at which time patients will undergo evaluation of disease response. Secondary endpoints include incidence of cytokine release syndrome, graft-vs-host disease, and clinical response. Exploratory endpoints aim to correlate VCAR33 properties with clinical response by characterizing T cell phenotypes within the VCAR33 product and by examining VCAR33 expansion and persistence after infusion. Follow up on trial will continue for up to 2 years after infusion followed by long term monitoring for up to 15 years. Patients may undergo second alloHCT for consolidation of remission or for rescue of prolonged cytopenia due to on-target off-tumor effects of VCAR33. *NCT number pending. Clinical trial information submitted to CT.gov on July 19, 2023.

The Genomic Landscape and Its Clinical Implication in NPM1-Mutated AML Patients: A Study within the AMLSG 09-09 Clinical Trial

Background: Mutations in the Nucleophosmin 1 gene ( NPM1 mut ) represent one of the most common genetic lesions in acute myeloid leukemia (AML).Based on its characteristic clinico-pathologic features, NPM1 mutAML has been recognized as a distinct entity among the category “AML with recurrent genetic abnormalities”. According to the ELN 2022 genetic risk-stratification, NPM1 mut AML, in the absence of FLT3-ITD mutation, is associated with a favorable prognosis. However, a significant proportion of these patients (pts) relapse after intensive therapy suggesting that other co-mutations may have an impact on outcome. Aims: To comprehensively characterize the genomic landscape and leukemogenic trajectoriesin a large cohort of NPM1 mut AML pts and to investigate its prognostic and predictive impact on outcome. Methods: Targeted DNA sequencing (mean read depth: 1817) on the entire coding region of 263 genes was performed in 568 NPM1 mut AML pts (median age: 58.7 years; 18-60 years, n=317; >60 years, n=251). All pts were enrolled in the randomized open-label Phase 3 AMLSG 09-09 trial [NCT00893399; Döhner H et al. Lancet Haematol 2023]. In this trial, pts were assigned to intensive chemotherapy plus all- trans retinoic acid with or without gemtuzumab ozogamicin; none of the pts received midostaurin. Results: In total n=3,058 variants (variant allele frequency of ≥1%) were identified in 195/263 genes. The median number of co-mutations was 3 (range 0-11). The most common co-mutated genes were DNMT3A (49.5%), FLT3-TKD (42.8%) PTPN11 (24.8%), NRAS (22.7%) TET2 (21.7%), IDH2 (21.3%), IDH1 (18%), and FLT3-ITD (17.3%). DNMT3AR882 hotspot mutations occurred more frequently in younger pts (36.6% vs 17.1%), while there was no difference for DNMT3AnonR882 mutations between the two age groups (21.8% and 21.9%). An age-dependent difference was also identified for mutations in myelodysplasia-related genes ( ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, and ZRSR2) as defined by the ICC, occurring with a higher incidence in older pts (30.3% vs 12.3% in younger pts). Analyzing the mutational pattern of co-mutations, we found statistically significant tertiary gene-gene interactions: e.g., NPM1- NFE2- STAG2 (p<.001), NPM1- IDH2- SRSF2 (p<.001), NPM1- CEBPA- TET2 (p<.001), NPM1- DNMT3AR882- NRAS (p=.002), and NPM1- ASXL1- SRSF2 (p=.004); mutual exclusivities were identified for NPM1- DNMT3AR882- DNMT3AnonR882 (p<.001), NPM1- IDH2- TET2 (p<.001), NPM1- DNMT3AR882- SRSF2 (p<.001), NPM1- IDH1- TET2 (p<.001), and NPM1- FLT3-ITD- KRAS (p<.002). Correlating co-mutation data with outcome, we found that DNMT3AR882 hotspot mutations confer inferior event-free (EFS) and overall survival (OS) only in younger pts (EFS, p<.001 vs p=.11, Figure 1a; OS, p=.003 vs p=.8), whereas DNMT3AnonR882 mutations did not impact prognosis within the two age groups. We also found a negative prognostic impact of IDH1 mutations which was restricted to younger pts (EFS, p=.05), whereas IDH2 mutations were associated with superior EFS in older pts (p=.04) and superior OS in both groups (p=.05 and p=.03). Of note, co-mutations occurring in one or more of the myelodysplasia-related genes did not impact EFS or OS (Figure 1b). In multivariable analysis (all pts) including age, WBC, LDH, allogeneic transplantation in CR1, and mutations with an incidence of at least 3% as covariables, age (HR,1.03; p<.001), DNMT3AR882 (HR, 1.86; p<.001), FLT3-ITD (HR, 1.54; p=.012), IDH1 (HR, 1.48; p=.009), MYC (HR, 1.83; p=.032), and WT1 (HR, 1.73; p=.012), were associated with an inferior EFS, while SMC3 mutation showed favorable EFS (HR, 0.44; p=.019). To further study the leukemogenic trajectories, we used an oncogenetic tree modeling algorithm, which yielded a tree with several main branches including DNMT3AR882, DNMT3AnonR882, FLT3-TKD , IDH1, IDH2, PTPN11, and TET2. These mutations might represent initiating events which predispose to additional events with further distinct branches. Conclusions: Our study provides comprehensive data on the genomic landscape and its clinical impact in pts with NPM1mut AML fit for intensive chemotherapy. The co-mutational pattern clearly differs between younger and older NPM1 mutAML pts. Using this large dataset allowed the identification of secondary and tertiary gene-gene interactions with significant impact on outcome. Further data analysis is ongoing and will be presented at the meeting.

CD33-TIM3 Dual CAR T Cells: Enhancing Specificity While Maintaining Efficacy Against AML

Background: The myeloid associated antigen CD33 is overexpressed in over 88% of Acute myeloid leukemia (AML) patients, making it a suitable target antigen for CAR T cell therapy across different genetic subtypes. Despite the development of clinical trial data, there remains a concern about on-target off-leukemia toxicity. To enhance specificity, we generated dual targeting CAR T cells that target CD33 and/or T-cell immunoglobulin and mucin-domain containing-3 (TIM3). The latter is known to be expressed on LSCs, but not on healthy hematopoietic precursor or stem cells. Notably, TIM3 is recognized for its inhibitory immunomodulatory role further enhancing the suitability of this target antigen. The objective of this research was to explore various CD33 and TIM3 dual-targeting CAR T cells approaches that enhance AML specificity and maintain high anti-AML activity. Methods: The hybridoma technology was used to generate antibodies against TIM3 immunized mice. Antibodies were screened for TIM3 specificity via ELISA and FACS. The anti-TIM3 single-chain variable fragment (scFv) DNA sequence was sequenced from hybridoma cells. Furthermore, the binding ability to TIM3 antigen (PDB ID: 5F71) was evaluated using AlphaFold. The CD33 scFv was derived from Gemtuzumab ozogamicin (clone: hP67.6). ScFv sequences and co-stimulation domains (CD28 or 4-1BB) were cloned into a pMP71 vector. Retrovirus for transduction was produced using the 293Vec-GALV and RD114 retroviral production system. In vitro co-culture assays of CAR T cells and target cells were performed to study the efficacy of CAR T cells. The cytotoxicity against wild-type and TIM3 transduced AML cell lines (THP-1 and OCI-AML3) was assessed by multiparameter flow cytometry (MPFC). The secretion of effector cytokines (IFN-γ, TNF, IL-2) was analyzed via CBA assays. In addition, avidity between CAR T cells and target cells was determined by Z-Movie analyzer. The different CAR constructs were screened for on-target off-tumor toxicity in colony forming unit assays (CFU) using isolated CD34 + hematopoietic stem and progenitor cells (HSPCs) from healthy doners after 14 days. In order to compare CAR constructs regarding long-term efficacy in antigen restimulation assays, CAR T cells were co-cultured with irradiated TIM3 transduced OCI-AML3 every 4 days at an E: T ratio of 1:1 for 24 days. Moreover, CAR T-cell proliferation, checkpoint marker expression and T-cell subset differentiation were analyzed via MPFC. Results: All dual CAR T cells (compound, split, tandem, pooled) were generated with high and robust transduction efficacy (Figure 1A). TIM3-dependent fratricide was not observed during CAR T cell manufacturing. Compared to single antigen targeting CAR T cells, dual CAR T cells showed enhanced cytotoxicity against AML cell lines and primary AML cells (Figure 1B). Moreover, we also observed a strong increase in the secretion of proinflammatory cytokines (IFN-γ and IL-2) and higher avidity of dual CAR T cells. Notably, split CAR T cells demonstrated greater specificity in cocultures directed against mono vs. dual-target antigen expression cell lines. In accordance with these observations, split CAR T cells did not exert on-target off-leukemia toxicity against healthy HSC in CFU assays. In the antigen restimulation assay, we observed that compound CAR T cells exhibited diminished expanding capacity and heightened expression of exhaustion markers in comparison to the other CAR T constructs. Conclusion: We developed multiple CD33 and TIM3 dual CAR T cells using both “AND” and “OR” gating strategies in this study. Our findings revealed that dual CAR T cells provided higher avidity and cytotoxicity compared to single targeting CAR T cells against dual antigen expressing target cells in vitro. Importantly, only the split CAR T constructs demonstrated specific killing of CD33 +TIM3 + cell lines and primary AML cells while sparing HSPCs. Prospectively, compound, tandem, pooled CD33 TIM3 specific CAR T cells might be helpful in a bridge to transplant setting, whereas split CAR T cells might provide a higher safety profile, thereby allowing a transplant independent approach. To advance our concepts, we are currently conducting in vivo experiments in an NSG mouse model.

Treatment Patterns and Outcomes of Patients with Acute Myeloid Leukemia (AML) from 2013 to 2022: A Connect ® Myeloid Registry Study

Introduction There has been a rapid evolution in diagnostic and management evaluation for AML, associated with the introduction of new therapies, some of which target specific mutations, over the past decade. The Connect ® Myeloid Registry (NCT01688011) is a multicenter, prospective, observational cohort study that began enrollment in December 2013 and represents a rich source of information to evaluate changes in disease course and outcomes over time in patients with myeloid diseases. We evaluated 10-year longitudinal data from patients with AML treated in real-world clinical practice at community and academic institutions to understand the evolution of diagnosis and treatment of patients with this myeloid condition. Methods Patients in the AML cohort were ≥ 55 years of age and newly diagnosed with AML according to the 2008 revised World Health Organization criteria and were grouped by year of diagnosis: 2013-2016 (Group 1; before commercial availability of numerous novel therapies including venetoclax, midostaurin, ivosidenib, enasidenib, gemtuzumab ozogamicin, and others), and 2017-2022 (Group 2; after availability of new therapies). Baseline demographic and clinical characteristics, treatment patterns, and outcomes were evaluated by group. Overall survival (OS) from the date of diagnosis was estimated by the Kaplan-Meier method. Results A total of 773 patients with AML (Group 1, n = 292; Group 2, n = 481) were assessed. Median (range) age was 70.0 years (55.0-91.0) in Group 1, and 71.0 years (55.0-97.0) in Group 2. Median OS was 11.0 months (95% confidence interval [CI]: 9.0-14.0) in Group 1, and 16.0 months (13.0-18.0) in Group 2 ( P = 0.039; Figure). A higher percentage of patients in Group 2 survived to 60 months compared with Group 1 ( Figure). Improved survival over time was primarily observed in patients < 75 years of age at diagnosis; median (95% CI) OS among patients < 75 years of age increased over time from 14.0 months (11.0-17.0) in Group 1 to 20.0 months (17.0-24.0) in Group 2 ( P = 0.022) but remained unchanged over time among patients ≥ 75 years of age (9.0 months [6.0-10.0] in Group 1; 9.0 months [6.0-13.0] in Group 2; P = NS). Rates of transplant increased significantly over time for younger patients; among those < 75 years of age at diagnosis, 45/201 (22%) in Group 1 received a transplant, compared with 99/318 (31%) in Group 2( P = 0.035). The proportion of patients receiving molecular testing increased over time from 68.8% in Group 1 to 86.9% in Group 2. The mean (standard deviation) number of mutations tested among those who underwent molecular testing also increased over time, from 6.1 (5.9) in Group 1 to 11.8 (7.4) in Group 2. Longer median (95% CI) OS was observed in patients who received molecular testing compared with those who did not: 14.0 months (11.0-17.0) versus 9.0 months (7.0-11.0) in Group 1; 16.0 months (13.0-19.0) versus 13.0 months (6.0-17.0) in Group 2. The proportion of patients receiving first-line treatment with intensive chemotherapy (IC) regimens was similar in the 2 time periods (Group 1, 51.0%; Group 2, 47.1%). Among patients not receiving IC, those in Group 2 increasingly received targeted therapies and venetoclax-based regimens and less-frequent low-intensity chemotherapy and supportive care. Conclusions In the AML cohort of Connect ® Myeloid, one of the longest-running US registries of myeloid diseases, we observed that patient characteristics at diagnosis were similar from 2013-2022. A statistically significant increase in median OS was observed over time. The increased rate of transplant, higher rates of molecular testing, and uptake of novel, targeted, treatments may have contributed to the improvement in survival. These results demonstrate the need for long-running, prospective observational studies to continue to understand rapidly changing treatment algorithms, combinations, and outcomes in AML.

MRD Directed Treatment Intensification with Either FLAG-Ida or DA-Cladribine Improves Survival in Older AML Patients: Results from the NCRI AML18 Randomised Trial

Background Following intensive chemotherapy in acute myeloid leukemia (AML), residual disease, assessed by failure to achieve a remission (CR/CRi) or the presence of measurable residual disease (MRD) in remission identifies a poor risk group of patients. In the NCRI AML16 trial for older adults (>60yrs), patients who were MRD+ve by flow cytometry in their remission bone marrow after course 1 had significantly poorer survival (26% at 3yrs vs 42% if MRD-ve) due to a higher risk of relapse (Freeman et al JCO 2016). These results suggested that flow cytometric MRD after course 1, by identifying patients who have a poor outcome with standard therapy, could be used to risk stratify for further treatment. However, although not infrequently used, it is uncertain whether chemotherapy intensification is of benefit to older adults with residual disease. In the AML18 trial we therefore conducted a course 2 randomization to evaluate MRD directed chemotherapy intensification in older adults. Methods AML18 patients who did not achieve MRD negativity after their first course (either not in CR/CRi or MRD+ve or MRD unknown) were randomized to either continue treatment with up to two courses of standard DA (Daunorubicin, AraC) (DA3+8 followed by DA2+5) or to receive up to 2 courses of intensified chemotherapy:- either FLAG-Ida or DA with Cladribine (DAC) (DA3+8, followed by DA2+5 both including Cladribine 5 mg/m 2 x 5 days). Course 1 had comprised DA (3+10) with 0, 1 or 2 doses of gemtuzumab ozogamicin. FLAG-Ida was dose reduced for patients over 70yrs and in course 3 for all patients (Fludarabine from 30mg/m 2 days 1-5 to 25mg/m 2 days 1-4, Idarubicin from 8mg/m 2 days 3-5 to 5mg/m 2 days 2-4). The DAC randomization was closed May 2019 due to drug supply issues. The primary endpoint was overall survival (OS). Rate ratios (RR) were used when appropriate to account for non-proportional hazards effect. Secondary endpoints included conversion to MRD negativity (defined as undetectable MFC-MRD) following course 2. Results Between Nov 2014 and Jan 2023, 523 patients (median age 67yrs) entered this randomization (193 DA, 191 FLAG-Ida, 139 DAC) following course 1 response assessment. Of these patients 164 (31%) were not in CR/CRi, 260 (50%) were in CR/CRi MRD+ve and the remaining 99 (19%) were in CR/CRi but with MRD unknown (due to an absence of a leukaemia-associated-immunophenotype at diagnosis or inadequate/missing samples). 99/477 (21%) of patients had adverse risk cytogenetics. All characteristics were balanced between arms. Median follow-up was 51 months. Following course 2, 47% (78/164) of those not in CR/CRi after course 1 converted to CR/CRi within 50 days: 55%, 57%, 34% for DA, DAC and FLAG-Ida respectively (DA vs DAC P=0.63, DA vs FLAG P=0.015). Of 282 patients providing MRD results after both course 1 and 2, 51% (60/117), 63% (50/79) and 58% (50/86) converted to MRD negativity after DA, DAC and FLAG-Ida respectively (DA vs DAC P=0.16, DA vs FLAG P=0.33). Greater hematological toxicity was seen with DAC or FLAG-Ida compared to DA (P<.001 for both platelet and neutrophil recovery). Day 60 mortality was increased in patients randomized to FLAG-Ida (9% vs 4% with DA and 4% with DAC, P=0.032). In total, 213 (41%) patients underwent allogeneic SCT (DA 42%, DAC 47%, Flag-Ida 35%). OS at 5yrs was 27%, 32% and 32% for DA, DAC and Flag-Ida respectively (DAC vs DA HR=0.82 95%CI 0.62-1.09, P=0.174; FLAG-Ida vs DA HR=0.90 95%CI 0.70-1.16, P=0.407). In subgroup analyses, comparing patients with known and unknown MRD status, there was no detectable survival benefit from intensification for MRD unknown patients (FLAG-Ida vs DA RR 1.52 95%CI 0.92-2.50, P value = 0.105; DAC vs DA RR 1.10, 95%CI 0.81-1.45, P value = 0.549). In a sensitivity analysis, excluding patients with unknown MRD, there was a significant OS benefit for both DAC (OS at 5yrs, 32% vs 22% for DA; RR 0.84, 95%CI 0.77-0.98, P=0.029, Figure A) and FLAG-Ida (OS at 5yrs, 34% vs 23% for DA; RR 0.71, 95%CI 0.54-0.96, P=0.026, Figure B). Conclusion In older AML patients with evidence of residual disease following first induction, we saw a significant long-term survival benefit for intensified therapy with both DAC and FLAG-Ida in a randomized comparison with DA. This was despite early toxicity, observed particularly after FLAG-Ida. DAC intensification appeared better tolerated, delivered more patients to transplant and was associated with a greater conversion to MRD negativity.

Outcomes for Children with High Risk Acute Myeloid Leukemia on the Myechild 01 International Phase III Clinical Trial

Background: Outcomes for pediatric acute myeloid leukemia (AML) remain disappointing, particularly for patients with poor risk cytogenetic/molecular genetic abnormalities and those who fail to achieve complete remission following course 1 of induction chemotherapy. Despite upfront allogeneic hematopoietic stem cell transplantation (HSCT) for these patients, high rates of relapse persist. The optimal approach to chemotherapy intensification and timing of HSCT for high risk (HR) patients remains unknown, with variable approaches employed by cooperative trial groups. Methods: The MyeChild 01 international phase III trial (NCT02724163) in children with de novo AML allocated patients up to 3 doses of gemtuzumab ozogamicin (GO 3mg/m 2/dose) during the first course of induction chemotherapy (mitoxantrone 12 mg/m2/dose x4; cytarabine 100 mg/m2/dose x20). Patients classified as HR after course 1 received FLA-Ida for course 2 followed by allogeneic HSCT. If required, a third course of bridging therapy (FLA) was given prior to HSCT. HR patients in MyeChild 01 included those with NUP98 fusions, selected KMT2A fusions ( KMT2A::MLLT10, KMT2A::MLLT4, KMT2A::AFF1, KMT2A::ABI1), CBFA2T3::GLIS2, DEK::NUP214, MECOM ( EVI1) rearrangements and all 12p abnormalities including MNX1::ETV6, in addition to the traditional HR abnormalities -7, -5/del(5q) and FLT3-ITD (without concurrent good risk abnormalities, including NPM1 mutations). Patients with induction failure after course 1 (≥ 5% blasts confirmed by flow) and those with non-HR cytogenetics/molecular genetics who remained MRD positive after course 2 (intermediate risk cytogenetics) or 3 (good risk cytogenetics) were also classified as HR. Here, we report the estimated 2-year outcomes for patients assigned HR post course 1 who received mitoxantrone and cytarabine and at least 1 dose of GO during course 1 (MA-GO). Outcomes of trial randomisations (1 vs 2 or 3 GO doses; consolidation for standard risk patients; HSCT conditioning) will be reported separately. Results: Of 749 patients enrolled at initial diagnosis, 183 received MA-GO during course 1 and were assigned HR post course 1. Of these, 172 (94%) patients had poor risk cytogenetic/molecular genetics, of which 32 also failed to achieve CR. Additionally, 11 (6%) patients did not have poor risk cytogenetic/molecular genetics but failed to achieve CR with MA-GO and thus were assigned to the HR group. Post course 1, 140 (77%) of these HR patients achieved CR/CRi, with 102/155 (66%) patients with evaluable samples achieving MRD negativity post course 1. Following course 1, 174 (95%) remained on trial and received FLA-Ida as course 2 and 163 patients (89%) proceeded to HSCT, 55 on trial and 108 following discontinuation from the trial. Estimated event-free survival (EFS) and overall survival (OS) at 2 years was 62% (95% CI: 56-70%) and 71% (64-78%) respectively (Figure 1 & 2). Estimated cumulative incidence of relapse (CIR) and death in remission at 2 years was 26% (19-33%) and 7% (3-11%) respectively. For HR patients who received MA-GO in course 1, on trial FLA-Ida as course 2 and on or off trial HSCT (n = 156), 2 year estimated outcomes were EFS 69% (62-77%), OS 77% (70-85%) and CIR 24% (17-32%). The most common cytogenetic/molecular genetic abnormalities were rearrangements of KMT2A (50/183, 27%), with KMT2A::MLLT10 predominating (70%). FLT3-ITD (19%), NUP98 fusions (14%), -7 (13%), abn(12p) (11%), del(5q) (8%) and CBFA2T3::GLIS2 (6%) accounted for the majority of other abnormalities with outcomes varying by subtype. Collectively, KMT2A-rearranged patients had EFS and OS of 68% (55-83%) and 71% (59-86%) respectively and CIR of 26% (12-40%). For FLT3-ITD, the EFS and OS was 75% (62-92%) and 83% (69-99%) respectively with a CIR of 14% (1-26%). Of the 25 patients with a NUP98 fusion, 17 (68%) were NUP98::NSD1. The EFS and OS for patients with NUP98 fusions was 71% (55-92%) and 96% (88-100%) respectively with CIR 25% (1-48%). Conclusions: Two intensive courses of induction chemotherapy, including GO and mitoxantrone in course 1 and FLA-Ida in course 2, consolidated with allogeneic HSCT, appears to be an effective approach for most HR patients. 2 year estimated outcomes for HR patients compare favourably to recent trials of GO in pediatric AML, with particularly encouraging data for patients with KMT2A-r and FLT3-ITD.

Immunotherapy in Acute Myeloid Leukemia: A Literature Review of Emerging Strategies.

In the last twenty years, we have witnessed a paradigm shift in the treatment and prognosis of acute myeloid leukemia (AML), thanks to the introduction of new efficient drugs or approaches to refine old therapies, such as Gemtuzumab Ozogamicin, CPX 3-5-1, hypomethylating agents, and Venetoclax, the optimization of conditioning regimens in allogeneic hematopoietic stem cell transplantation and the improvement of supportive care. However, the long-term survival of non-M3 and non-core binding factor-AML is still dismal. For this reason, the expectations for the recently developed immunotherapies, such as antibody-based therapy, checkpoint inhibitors, and chimeric antigen receptor strategies, successfully tested in other hematologic malignancies, were very high. The inherent characteristics of AML blasts hampered the development of these treatments, and the path of immunotherapy in AML has been bumpy. Herein, we provide a detailed review of potential antigenic targets, available data from pre-clinical and clinical trials, and future directions of immunotherapies in AML.

Development of a gene edited next-generation hematopoietic cell transplant to enable acute myeloid leukemia treatment by solving off-tumor toxicity

Immunotherapy of acute myeloid leukemia (AML) has been challenging because the lack of tumor-specific antigens results in "on-target, off-tumor" toxicity. To unlock the full potential of AML therapies, we used CRISPR-Cas9 to genetically ablate the myeloid protein CD33 from healthy donor hematopoietic stem and progenitor cells (HSPCs), creating tremtelectogene empogeditemcel (trem-cel). Trem-cel is a HSPC transplant product designed to provide a reconstituted hematopoietic compartment that is resistant to anti-CD33 drug cytotoxicity. Here, we describe preclinical studies and process development of clinical-scale manufacturing of trem-cel. Preclinical data showed proof-of-concept with loss of CD33 surface protein and no impact on myeloid cell differentiation or function. At clinical scale, trem-cel could be manufactured reproducibly, routinely achieving >70% CD33 editing with no effect on cell viability, differentiation, and function. Trem-cel pharmacology studies using mouse xenograft models showed long-term engraftment, multilineage differentiation, and persistence of gene editing. Toxicology assessment revealed no adverse findings, and no significant or reproducible off-target editing events. Importantly, CD33-knockout myeloid cells were resistant to the CD33-targeted agent gemtuzumab ozogamicin invitro and in vivo. These studies supported the initiation of the first-in-human, multicenter clinical trial evaluating the safety and efficacy of trem-cel in patients with AML (NCT04849910).

Gemtuzumab Ozogamicin Monotherapy Is a Well-tolerated Palliative Chemotherapy Option in Pediatric Multiply Relapsed Acute Myeloid Leukemia: A Multicenter Case Series and Review of the Literature.

Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody that is Food and Drug Administration approved in upfront acute myeloid leukemia (AML) for patients over 1-month old, and for relapsed or refractory AML in patients over 2 years old. GO is now integrated in upfront pediatric AML treatment, and often in CD33+ relapse treatment combined with intensive conventional chemotherapy. Although GO was initially tested as a monotherapeutic agent in relapsed or refractory AML, there are few data in pediatric patients supporting this indication. In this review, we report 4 cases of multiply relapsed pediatric AML patients who were treated with GO monotherapy with palliative intent. Three of 4 patients obtained a complete response with GO reinduction, either as monotherapy or paired with conventional chemotherapy. Three patients remained in remission respectively for 5, 17, and 9 months with GO continuation monotherapy. The literature was reviewed regarding the use of GO in pediatric AML relapse settings.

Fractionated vs single-dose gemtuzumab ozogamicin with determinants of benefit in older patients with AML: the UK NCRI AML18 trial

AbstractAddition of gemtuzumab ozogamicin (GO) to induction chemotherapy improves outcomes in older patients with acute myeloid leukemia (AML), but it is uncertain whether a fractionated schedule provides additional benefit to a single dose. We randomized 852 older adults (median age, 68-years) with AML/high-risk myelodysplasia to GO on day 1 (GO1) or on days 1 and 4 (GO2) of course 1 induction. The median follow-up period was 50.2 months. Although complete remission (CR) rates after course 1 did not significantly differ between arms (GO2, 63%; GO1, 57%; odds ratio [OR], 0.78; P = .08), there were significantly more patients who achieved CR with a measurable residual disease (MRD)<0.1% (50% vs 41%; OR, 0.72; P = .027). This differential MRD reduction with GO2 varied across molecular subtypes, being greatest for IDH mutations. The 5-year overall survival (OS) was 29% for patients in the GO2 arm and 24% for those in the GO1 arm (hazard ratio [HR], 0.89; P = .14). In a sensitivity analysis excluding patients found to have adverse cytogenetics or TP53 mutations, the 5-year OS was 33% for GO2 and 26% for GO1 (HR, 0.83; P = .045). In total, 228 (27%) patients received an allogeneic transplantation in first remission. Posttransplant OS was superior in the GO2 arm (HR, 0.67; P = .033); furthermore, the survival advantage from GO2 in the sensitivity analysis was lost when data of patients were censored at transplantation. In conclusion, GO2 was associated with a greater reduction in MRD and improved survival in older adults with nonadverse risk genetics. This benefit from GO2 was dependent on allogeneic transplantation to translate the better leukemia clearance into improved survival. This trial was registered at www.isrctn.com as #ISRCTN 31682779.

A clinical trial of zosuquidar plus gemtuzumab ozogamicin (GO) in relapsed or refractory acute myeloid leukemia (RR AML): evidence of efficacy based on leukemic blast P-glycoprotein functional phenotype.

To evaluate safety, tolerability, potential efficacy, and pharmacodynamics (PD) of zosuquidar (Zos) in combination with gemtuzumab ozogamicin (GO) in elderly patients with relapsed or refractory (RR) acute myeloid leukemia (AML). Patients with RR AML (N = 41) were treated with Zos as a 48-h continuous intravenous infusion initiated 4h prior to a 2-h infusion of GO on days 1 and 15. P-glycoprotein (P-gp) status of the patients' leukemic blasts and PD determinations were assessed with ex vivo bioassays. Patient outcomes were analyzed for the total cohort and as stratified into P-gp-positive (P-gp +) and P-gp-negative (P-gp‒) subgroups. The eligible cohort exhibited a 34% overall remission rate (ORR), a composite of patients that exhibited complete remission (CR), CR with incomplete platelet recovery, or morphologic remission. Patients with 1st relapsed disease exhibited 40% ORR. P-gp phenotype did not significantly predict ORR. However, the P-gp + subgroup exhibited a greater median overall survival (OS) of 6.0months vs. 1.8months for patients in the P-gp‒ subgroup (p = 0.01). PD analyses revealed 90-95% inhibition of blast P-gp function during Zos infusion. Treatment related toxicities were observed and resolved with decrease or discontinued Zos or GO dosages. Zos plus GO elicited appreciable ORR for an elderly patient population with RR AML. The greater OS of the P-gp + subgroup vs. the P-gp‒ subgroup suggests that patients with P-gp + leukemic blasts were being more effectively targeted by GO with Zos co-therapy. The poorer OS of the P-gp‒ subgroup suggests activity of Zos-insensitive multidrug resistant mechanisms. NCT00233909; First posted October 06, 2005.

Development of nanoparticles for the Novel anticancer therapeutic agents for Acute Myeloid Leukemia

Acute myeloid leukaemia is becoming more predominant in blood cancer in geriatrics people groups. In 2017, four new therapeutic candidates have been approved by the FDA: Enasidenib, CPX 351, Midostaurin, and Gemtuzumab ozogamicin; with the approval of Venetoclax and Daurismo, additional advances were achieved in 2018. Ivosidenib and gilteritinib were also accepted as single-agent therapy in persistent and recurrent AML 2018. Most of the anticancer drugs belong to Biopharmaceutical classification system-II (BSC), and BCS class-IV has poor bioavailability because of solubility issues. We will overcome this problem by preparing nanoparticles of this drug by using different nanoparticle preparation methods.

ZBTB16::RARA variant acute promyelocytic leukemia (vAPL) treated with gemtuzumab ozogamicin (GO) with unique pathology and genetic findings.

ZBTB16::RARA variant acute promyelocytic leukemia (vAPL) treated with gemtuzumab ozogamicin (GO) with unique pathology and genetic findings.

Children's Oncology Group's 2023 blueprint for research: Myeloid neoplasms.

During the past decade, the outcomes of pediatric patients with acute myeloid leukemia (AML) have plateaued with 5-year event-free survival (EFS) and overall survival (OS) of approximately 46 and 64%, respectively. Outcomes are particularly poor for those children with high-risk disease, who have 5-year OS of 46%. Substantial survival improvements have been observed for a subset of patients treated with targeted therapies. Specifically, children with KMT2A-rearranged AML and/or FLT3 internal tandem duplication (FLT3-ITD) mutations benefitted from the addition of gemtuzumab ozogamicin, an anti-CD33 antibody-drug conjugate, in the AAML0531 clinical trial (NCT00372593). Sorafenib also improved response and survival in children with FLT3-ITD AML in the AAML1031 clinical trial (NCT01371981). Advances in characterization of prognostic cytomolecular events have helped to identify patients at highest risk of relapse and facilitated allocation to consolidative hematopoietic stem cell transplant (HSCT) in first remission. Some patients clearly have improved survival with HSCT, although the benefit is largely unknown for most patients. Finally, data-driven refinements in supportive care recommendations continue to evolve with meaningful and measurable reductions in toxicity and improvements in EFS and OS. As advances in application of targeted therapies, risk stratification, and improved supportive care measures are incorporated into current trials and become standard-of-care, there is every expectation that we will see improved survival with a reduction in toxic morbidity and mortality. The research agenda of the Children's Oncology Group's Myeloid Diseases Committee continues to build upon experience and outcomes with an overarching goal of curing more children with AML.

UCHMC 1812: A phase 1b trial of CPX-351 plus gemtuzumab ozogamicin for relapsed/refractory acute myeloid leukemia.

7024 Background: Gemtuzumab ozogamicin (GO) is effective in favorable-risk acute myelogenous leukemia (AML), while its activity is limited in higher-risk AML in part due to multi-drug resistance (MDR) mechanisms, particularly P-glycoprotein efflux pumps. CPX-351 provides a survival benefit in secondary AML, a disease characterized by high MDR activity. The objective of this trial is to utilize CPX-351 as a bulk cytoreduction agent, to first reduce the high MDR leukemia clones, followed by sequential treatment with GO in a more favorable leukemia environment. Methods: This was a multicenter phase Ib trial of CPX-351 plus GO in relapsed/refractory (R/R) AML patients with standard 3+3 dose escalation design (NCT03904251). Cohort A was treated with CPX-351 100 u/m2 on days 1, 3, and 5 plus GO 3 mg/m2 (max 4.5 mg) on day 7. Cohort B was treated with the same regimen plus an additional dose of GO 3 mg/m2 on day 4. The primary endpoint was the maximum tolerated dose (MTD), defined as &lt; 2 dose limiting toxicities (DLTs) in the highest dose cohort. Secondary endpoints were IWG complete remission (CR) rate at day 28-42, liver veno-occlusive disease (VOD) rate diagnosed by the Baltimore criteria, and time of hematologic recovery (defined as ANC &gt; 1000/uL and platelet count &gt; 100,000/uL). Patients were enrolled at 4 University of California Hematologic Malignancies Consortium (UCHMC) centers: UC Los Angeles, UC San Francisco, UC Davis, and UC Irvine. Results: Thirteen participants were enrolled. The median age was 63 years (range 29-75). Eleven had relapsed disease, and two had refractory disease. Most received one prior line of therapy (n = 9). Seven had ELN 2022 adverse-risk disease at initial diagnosis, and two had intermediate-risk disease. The MTD was not reached. DLTs were observed in 1/6 participants in cohort A (grade 3 rash), and 1/6 participants in cohort B (grade 5 intracranial hemorrhage in the setting of severe thrombocytopenia). There were no cases of liver VOD. Of 12 evaluable participants, 4 achieved CR (33%), of whom 3 were negative for measurable residual disease by multiparametric flow cytometry, and 1 one achieved partial remission. The median age of responders was 30 years (range 28-65). The median time to return of normal hematopoiesis in those who achieved remission was 37 days (range 36-43). Three participants received allogeneic hematopoietic cell transplant (alloHCT) following investigational therapy: one remains in remission 34 months post-transplant, one died of infectious complications shortly after alloHCT, and one relapsed at day +60. Conclusions: CPX-351 plus two doses of GO 3 mg/m2 is a feasible treatment with acceptable toxicity and reasonable marrow recovery kinetics. However, only three participants went on to curative alloHCT. Further evaluation for efficacy in a larger patient population is needed to determine the utility of this regimen in R/R AML. Clinical trial information: NCT03904251 .

Treatment phase stratified outcomes of core binding factor acute myeloid leukemia.

e19055 Background: Mutations in core binding factor (CBF) are associated with a favorable prognosis in acute myeloid leukemia (AML). However, between 30-40% of patients with CBF-AML relapse, and relative outcomes with each subsequent line of therapy remain unclear. Additionally, the overall survival of CBF-AML compared to other favorable risk molecular aberrations — such as NPM1mut and CEBPA — is unknown in light of the addition of monoallelic CEBPA in ELN 2022. Therefore, the purpose of this study was to clarify the outcomes of CBF-AML relative to other favorable risk aberrations and to determine the relative overall survival associated with each subsequent relapse. Methods: We retrospectively analyzed 46 consecutive patients with CBF-AML treated from January 2013 to January 2022 at VCU Massey Cancer Center that underwent intensive chemotherapy (IC) with or without gemtuzumab ozogamicin. During the same study period, we analyzed a comparison cohort of 272 consecutive patients: 103 ELN 2017 intermediate-risk patients, 111 adverse-risk patients, eight patients with mono- or biallelic mutations in CEBPA, and 50 with ELN 2017 favorable-risk NPM1mut. All patients were treated with front-line IC. We analyzed survival by the Kaplan-Meier method and compared groups with the log-rank test. Results: We analyzed 46 patients with CBF-AML across 136 treatment phases. Patients with CBF-AML had superior overall survival compared to patients with NPM1mut (median overall survival not reached at a median follow-up time of 5.0 years versus 21.0 m., p = 0.028). There were no differences in survival between CBF-AML and AML with monoallelic or biallelic mutations in CEBPA at a median follow-up time of 3.7 years (not reached, p = 0.976). Expectedly, the overall survival for CBF-AML was superior to ELN 2017 intermediate (30.1 m., p = 0.011) and adverse (10.9 m., p &lt; 0.0001) risk disease. Next, we analyzed survival trends in the relapsed or refractory setting for CBF-AML by lines of therapy, using ELN 2017 intermediate and adverse risk cohorts as a comparison. During the first relapse, CBF-AML was associated with a significantly superior overall survival compared to the adverse cohort (19.1 m. versus 10.0 m., p = 0.024) but not the intermediate cohort (14.5 m., p = 0.734). The absence of KITmut was not associated with improved survival compared to the ELN 2017 intermediate category at the first relapse ( p = 0.610). At the second relapse, the survival disparity disappeared between the CBF-AML and adverse risk groups (7.7 m. vs 4.0 m., p = 0.964). Conclusions: CBF-AML was associated with similar survival to mono- or biallelic mutations in CEBPA, and significantly prolonged overall survival compared to NPM1mut. Relative to a matched cohort of adverse-risk AML at the time of the first relapse, outcomes of relapsed CBF-AML remain favorable. The relative overall survival benefit of CBF-AML disappeared at the time of the second relapse.

Clinical outcomes of core binding factor acute myeloid leukemia in the modern era.

e19054 Background: Acute myeloid leukemia (AML) with alterations in core binding factor (CBF) has a favorable prognosis. The impact of complex cytogenetics or ELN 2022 adverse genetic risk markers — such as ASXL1, RUNX1, EZH2, SRSF2, (and the rest of the secondary-type mutations [STMs]) and TP53 — in CBF-AML is unclear. Additionally, treatment outcomes in CBF-AML using front-line novel approaches, such as a hypomethylating agent (HMA; decitabine or azacitidine) with venetoclax, are unknown. This study analyzed outcomes of CBF-AML with respect to higher-risk molecular and cytogenetic cohorts and treatment approaches. Methods: We identified 58 consecutive patients with CBF-AML treated at VCU Massey Cancer Center from January 1, 2013 to January 1, 2022. We used Fisher’s exact test for between-group comparisons. We analyzed survival by the Kaplan-Meier method and compared groups with the log-rank test. The date of death was used to calculate overall survival; patients were censored at the date of the last contact. Measurable residual disease (MRD) was assessed using PCR-based methods or multiparameter flow cytometry with a minimum sensitivity of 10-3. Results: We analyzed 58 patients with inv(16) or t(8;21) AML treated in the front-line setting. Seven of these patients had concomitant genetic or molecular abnormalities typically considered high risk, including complex cytogenetics or TP53mut. Forty-nine (84.5%) patients received intensive chemotherapy (IC) with FLAG, CPX-351, or conventional 7+3 with or without gemtuzumab ozogamicin; nine patients (15.5%) received lower-intensity therapies with HMAs with or without venetoclax. No differences in overall survival were seen between the patients with CBF-AML with or without complex cytogenetics or TP53mut (not reached for either cohort, median follow-up time of 6.1 y. and 5.0 y., respectively, p = 0.969). There was no difference in the rates of MRD negativity in CBF-AML with or without complex cytogenetics or TP53mut ( p = 0.544). The presence of secondary-type mutations also did not appear to significantly impact survival in CBF-AML ( p = 0.654). There was no difference in the rates of MRD negativity in CBF-AML with STMs and those without STMs ( p = 0.500). Patients that were ineligible for IC and were treated with venetoclax + HMA or HMA monotherapy had significantly reduced composite complete remission rates (CRR; CR + CRi; 25% vs 91.3%, p = 0.007) and median overall survival (3.7 m. versus not reached, p = 0.038). Conclusions: Our data confirm the superior outcomes in induction candidates of CBF-AML treated with IC. The presence of complex cytogenetics, TP53mut, or secondary-type mutations did not appear to influence the rates of MRD negativity or overall survival in CBF-AML.

Disparities in uptake of novel therapies for acute myeloid leukemia.

6540 Background: Multiple novel therapies have recently been approved to treat acute myeloid leukemia (AML). Inequities in the uptake of novel treatments have been seen in other cancers but are not known for this population. Methods: We performed a retrospective analysis of the nationwide Flatiron Health electronic health record (EHR)-derived deidentified database. We assessed sociodemographic associations with novel AML therapies use within two-years of Food and Drug Administration (FDA) approval from 1/2014-8/2022. Therapies were: glasdegib, venetoclax, ivosidenib, midostaurin, CPX-351, gilteritinib, enasidenib, and gemtuzumab ozogamicin (GO). Univariable associations were assessed using X2 testing. Logistic regression modeling of community practices assessed associations between novel therapy receipt and sociodemographics adjusted by treatment year. Variable categories are shown. Results: Of 8081 patients in 280 clinics, 3102 (38%) received at least one novel therapy. The cohort was predominately older (69; interquartile range [57, 77]), male (56%), non-Hispanic (NH)-White (88%), and treated at a community practice (75%). There were 4808 patients treated within 24-months of a novel therapy approval, of which 1937 (40%) received a novel therapy. Venetoclax represented 59% of novel treatments prescribed. Bivariate associations were seen between novel therapy receipt within 24-months of approval and high SES and non-Hispanic (NH)-White race-ethnicity; similar associations were seen when assessed at the treatment regimen level. In a logistic regression model of community practices (N=2,459), older patients (OR 1.01; 95%CI 1.00, 1.02), females (OR 1.2; 95% CI 1.0,1.4), and those from high (vs low) SES (OR 1.4; 95%CI 1.1, 1.6) were more likely to receive novel therapy; there were no associations with sex or race-ethnicity. Conclusions: In this large national database of adults with AML, almost half received novel therapy within 24-months of FDA approval. Though there was no dichotomous difference in uptake by race-ethnicity in community practices, younger and more affluent patients were more likely to receive novel therapy, concerning for disparities in uptake. [Table: see text]