Primary Refractory Acute Myeloid Leukemia Research Articles

Haploidentical transplantation in primary refractory/relapsed secondary vs de novo AML: from the ALWP/EBMT

AbstractWe compared the outcomes of haploidentical stem cell transplantation (haplo-HSCT) with posttransplant cyclophosphamide (PTCy) in 719 patients with primary refractory (PR) or first relapse (Rel) secondary acute myeloid leukemia (sAML; n = 129) vs those with de novo AML (n = 590), who received HSCT between 2010 and 2022. A higher percentage of patients with sAML vs de novo AML had PR disease (73.6% vs 58.6%; P = .002). In 81.4% of patients with sAML , the antecedent hematological disorder was myelodysplastic syndrome. Engraftment was 83.5% vs 88.4% in sAML and de novo AML, respectively (P = .13). In multivariate analysis, haplo-HSCT outcomes did not differ significantly between the groups: nonrelapse mortality hazard ratio (HR), 1.38 (95% confidence interval [CI], 0.96-1.98; P = .083), relapse incidence HR, 0.68 (95% CI, 0.4.7.-1.00; P = .051). The HRs for leukemia-free survival, overall survival, and graft-versus-host disease (GVHD)–free, and GVHD and relapse–free survival were 0.99 (95% CI, 0.76-1.28; P = .94), 0.99 (95% CI, 0.77-1.29; P = .97), and 0.99 (95% CI, 0.77-1.27; P = .94), respectively. We conclude that outcomes of haplo-HSCT with PTCy are not different for PR/Rel sAML in comparison with PR/Rel de novo AML, a finding of major clinical importance.

Gemtuzumab ozogamicin for relapsed or primary refractory acute myeloid leukemia in children-the Polish Pediatric Leukemia and Lymphoma Study Group experience.

Gemtuzumab ozogamicin (GO), one of the first targeted drugs used in oncology, consists of an anti-cluster of differentiation 33 (CD33) monoclonal antibody bound to a derivative of cytotoxic calicheamicin. After the drug withdrawn in 2010 due to a significantly higher rate of early deaths, GO regained approval in 2017 for the treatment of newly diagnosed, refractory, or relapsed acute myeloid leukemia (AML) in adults and children over 15 years of age. The objective of the study was a retrospective analysis of clinical characteristics, treatment outcomes, and GO toxicity profile in children with primary refractory or relapsed (R/R) AML treated in Poland from 2008 to 2022. Data were collected through the Polish Registry of Acute Myeloid Leukemia. From January 2008 to December 2022, 35 children with R/R AML were treated with GO in seven centers of the Polish Pediatric Leukemia and Lymphoma Study Group. Most of the children (30 of 35) received only one GO cycle in combination with various chemotherapy cycles (IDA-FLA, DOXO-FLA, FLA, FLAG, and others). Eighteen children (51%) achieved complete remission (CR), 14 did not respond to treatment, and three progressed. GO therapy was followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) in 18 children in CR. The 5-year overall survival (OS) after GO therapy was 37.1% ± 8.7% for the total cohort. There was a trend toward a superior outcome in patients with strong expression of CD33 expression (over 50% positive cells) compared with that in patients with lower expression of CD33 (OS, 41.2% ± 11.9% versus 27.8% ± 13.2%; p = 0.5; 5-year event-free survival, 35.4% ± 11.6% versus 25.7% ± 12.3%; p = 0.5, respectively). Children under 15 years have better outcome (OS, 34.9% ± 10.4% versus 30% ± 14.5%, p = 0.3). The most common adverse events were bone marrow aplasia, fever of unknown origin, infections, and elevated liver enzyme elevation. Sinusoidal obstruction syndrome occurred in two children. The use of GO in severely pretreated children, including those under 15 years of age, with previous failure of AML treatment is a feasible and effective bridging therapy to allo-HSCT with an acceptable toxicity profile.

Azacitidine-venetoclax versus azacitidine salvage treatment for primary induction failure or first relapsed acute myeloid leukaemia patients.

To compare the efficacy of venetoclax-azacitidine (VEN-AZA) with AZA in the real-life for patients with first relapsed or refractory acute myeloid leukaemia (R/R AML). We retrospectively analysed R/R AML patients treated with VEN-AZA at the Institut Paoli Calmettes between September 2020 and February 2022. We compared them to a historical cohort of patients treated with AZA between 2010 and 2021. Thirty-five patients treated with VEN-AZA were compared with 140 patients treated with AZA. There were more favourable cytogenetics (25.7% vs. 8.6%; p = 0.01) and less FLT3-ITD mutated AML (8.8% vs. 25.5%; p = .049) in the VEN-AZA group. The overall 30-day mortality rate was 7.4% and the overall 90-day mortality was 20%, with no difference between the groups. The complete remission rate was 48.6% in the VEN-AZA group versus 15% (p < .0001). The composite complete response rate was 65.7% in the VEN-AZA group versus 23.6% (p < .0001). OS was 12.8 months in the VEN-AZA group versus 7.3 months (p = 0.059). Patients with primary refractory AML, poor-risk cytogenetics, prior hematopoietic stem-cell transplantation (HSCT) and FLT3-ITD mutated AML had lower response and survival rates. VEN-AZA was associated with a better response rate and a longer survival than AZA monotherapy in AML patients who relapsed after or were refractory tointensive chemotherapy.

Psychiatric and Substance Use Disorders Are Independent Predictors of Treatment Response and Outcomes in United States Veterans with Newly Diagnosed Acute Myeloid Leukemia Treated with Venetoclax Combinations

BACKGROUND: Venetoclax (VEN) combinations have become the standard frontline therapy for patients with newly diagnosed acute myeloid leukemia (AML) who are deemed unable to tolerate intensive induction chemotherapy, either due to age or comorbidities. However, outcomes in the real-world setting have been inferior to those observed in clinical trials. Preexisting psychiatric diagnoses and substance use disorders (SUDs) have previously been associated with increased mortality in patients with cancer, but their prognostic influence in veterans with AML is unclear. The aim of this study was to measure the prevalence of psychiatric and SUDs in veterans with AML treated with VEN combinations, determining the impact of these conditions on treatment response and outcomes. METHODS: This was a retrospective cohort study of veterans with newly diagnosed AML who received frontline therapy with VEN combinations within the national Veterans Affairs (VA) Healthcare System. To measure the prevalence of psychiatric and SUDs, we used the Centers for Medicare and Medicaid Services (CMS) Chronic Conditions Data Warehouse algorithm, which tracks health conditions by administrative claims data with International Classification of Diseases (ICD) diagnostic and procedural codes. Our endpoints were rates of complete remission or complete remission with incomplete marrow recovery (CR/CRi), early mortality (EM, or death within 60 days of treatment initiation), intensive care unit (ICU) admissions, and overall survival (OS). We evaluated the relationship between comorbid medical conditions and outcomes using Kaplan-Meier analysis and Cox proportional hazards regression models, first unadjusted, and then adjusted for all covariates. Patients who underwent allogeneic stem cell transplantation (HSCT) were excluded from statistical analyses. RESULTS: We identified 452 veterans treated with VEN up to April 1, 2022 (Table 1). In combination with VEN, 60% (n=270) received azacitadine, 37% (n=168) received decitabine, and 3% (n=14) received low-dose cytarabine. Median age was 74.3 years (IQR: 71.2-78.5) with 52% ≥75 years. By European LeukemiaNet (ELN) 2017 risk classification, 61% (n=274) were classified as adverse risk. Forty-six percent (n=206) of veterans had a preexisting psychiatric diagnosis, and 19% (n=84) had SUDs; 11% (n=49) had both comorbidities. Psychiatric disorders were significantly more prevalent in younger veterans (68% in &amp;lt;65 years vs 50% in 65-74 years vs 39% in ≥75 years, p&amp;lt;0.003); same was true for SUDs (38% in &amp;lt;65 years vs 26% in 65-74 years vs 9% in ≥75 years, p&amp;lt;0.001). For the entire cohort, CR/CRi was achieved by 57% (n=257), and only 3% (n=12) received HSCT. Zero veterans with SUDs and 8 with psychiatric diagnoses were transplanted. At the end of study period, 69% (n=310) had died. Median OS was 216 days (95% CI: 195-254). The 60-day mortality rate was 20% (n=87), of which 8 veterans had primary refractory AML. ICU admissions after treatment initiation was significantly higher in veterans with SUDs compared to those without history of SUDs (5.0 versus 2.2 per 5 person-years, p&amp;lt;0.001). On multivariable analyses (Table 2), both psychiatric and SUDs were independently associated with decreased odds of CR/CRi. Veterans with psychiatric disturbances had a 1.97 times higher hazard of EM (95% CI: 1.16-3.39, p=0.01) and a 1.28 times higher hazard of death (95% CI: 1.00-1.64, p=0.05) compared to veterans without concurrent psychiatric disorders. CONCLUSION: Psychiatric diagnoses and SUDs were not only prevalent among veterans with AML, but they also negatively impacted treatment response, EM, and OS-independently of age, sociodemographic variables, markers of disease risk, and VEN combination. Veterans with SUDs also had significantly higher ICU admissions after treatment initiation for AML. Compared to published clinical trials data, veterans experienced inferior outcomes. Veterans with psychiatric and SUDs may have difficulty adhering to regimens, reemergence of their mental instability and illness that is triggered by AML diagnosis and its treatment, or biologic mechanisms associated with these comorbidities. Better understanding of these factors contributing to health disparities and targeting these comorbidities with supportive care interventions alongside AML-specific therapy may improve outcomes and warrant further study.

Comparative Effectiveness of Reinduction Approaches for Pediatric Relapsed Acute Myeloid Leukemia

Introduction: Intensive frontline chemotherapy achieves initial remission rates above 80% in pediatric acute myeloid leukemia (AML), however, approximately half of patients relapse, and overall survival (OS) after relapse is poor. There is a paucity of comparative effectiveness data on salvage regimens to inform selection of optimal post-relapse therapy. The objective of this analysis was to compare outcomes following relapse by prevalent reinduction regimens in a multi-center real-world dataset. Methods: Patients 18 years and younger who had received frontline chemotherapy for AML between 2011-2019 at 12 pediatric institutions were eligible for inclusion. Trained personnel completed manual chart abstraction to obtain demographics, diagnosis, treatment, and outcome information. The analysis included patients who achieved morphologic remission and then experienced disease relapse; patients with primary refractory AML and those who pursued palliative therapy only after relapse were excluded. Prevalent reinduction regimens were classified as (1) intensive without anthracycline [e.g. fludarabine/cytarabine and high-dose cytarabine-containing regimens], (2) intensive with anthracycline (e.g. CPX-351, mitoxantrone/cytarabine and cytarabine/daunorubicin/etoposide), and (3) non-intensive (including azacytidine or decitabine-based regimens). Primary outcomes were OS after relapse and end reinduction disease response defined by morphologic remission (&amp;lt;5% blasts) and measurable residual disease (MRD)-negative remission (&amp;lt;0.1% blasts). Covariate distributions were compared by reinduction regimen using chi-square tests. Survival analyses used Kaplan-Meier methods and multivariable cox proportional hazards models. End induction response was evaluated using logistic regression. Adjustment was made for covariates found to both differ by reinduction regimen and be associated with outcome, regardless of statistical significance. Results: Of 530 patients, 157 (29.6%) experienced a relapse at a median of 9.7 months (IQR 6.5-16.3) after initial diagnosis. Median post-relapse follow-up was 2.2 years (IQR 1.1-3.2). One- and 2-year OS rates from relapse were 44.9 ± 4.1% and 38.6 ± 4.1%, respectively. Of 157 patients with relapse, 129 from 9 institutions had available information on post-relapse treatment and pursued reinduction with curative intent. Patients were 48.8% female, 27.1% Hispanic, 14.7% non-Hispanic Black and had a median age of 7.1 years (IQR 2.70-14.2) at relapse. Most patients (89.2%) relapsed after completion of frontline therapy, and 24% had undergone hematopoietic cell transplantation (HCT) in first clinical remission. Reinduction regimens were as follows: 79 (61.2%) received intensive reinduction without anthracycline, 34 (26.4%) received intensive reinduction with anthracycline and 16 (12.4%) received non-intensive reinduction. Patients with a non-intensive reinduction were more likely to have relapsed within one year of initial diagnosis (50% versus 34%, p = 0.23) and undergone transplant prior to relapse (75.0% versus 16.8%, p &amp;lt; 0.001). Covariates were balanced across intensive induction regimens. One-year OS was 50.3 ± 4.6%, with 63 (40.1%) achieving morphologic remission and 40 (31.0%) achieving an MRD-negativity after first reinduction cycle. Seventy-three patients (56.9%) underwent HCT after relapse; 11 (15.1%) received a second transplant. OS curves and adjusted outcome comparisons by reinduction regimen are shown in the Figure and Table. One-year OS was 51.1 ± 5.8%, 60.2 ± 9.0% and 26.7 ± 11.4% for intensive therapy without anthracycline, with anthracycline and non-intensive, respectively. However, after adjustment hazard ratios (HRs) were not statistically significant [HR = 0.85 (p = 0.65) and 1.77 (p = 0.23) for intensive with anthracycline and non-intensive, compared to non-intensive without anthracycline, respectively]. Conclusions: After controlling for patient, disease and treatment characteristics, we did not identify a significant difference in remission rates or OS by reinduction approaches for pediatric relapsed AML. Although anthracycline-based reinduction did not improve OS, adjusted point estimates suggest that anthracyclines may improve end reinduction disease response. Ongoing cohort expansion will enable comparative effectiveness analyses of specific reinduction regimens.

Overcoming Venetoclax (Ven) Resistance through Glutamine (Gln) Depletion: Final Analysis of the Phase 1 Trial of Ven and Pegcrisantaspase (PegC) Combination in Relapsed and Refractory (R/R) Acute Myeloid Leukemia (AML)

Background: Ven-based therapies have been an advancement in the front-line treatment of AML; however development of resistance is common and the efficacy of Ven-containing regimens in R/R AML has been far less promising. We reported in vitro and in vivo depletion of Gln induced by long-acting Erwinia asparaginase, PegC, inhibited proliferation of complex karyotype (CK) AML and synergistically enhanced the antiapoptotic activity of Ven-mediated antagonism of Bcl-2 by decreasing the expression of proteins such as Mcl-1, whose translation is cap-dependent. Here we report the final results of our phase 1 clinical trial (NCT04666649) of VenPegC for treatment of R/R AML including patients (pts) previously treated with Ven. Methods: Pts received Ven 400 mg on D1-28 and PegC (500, 750, 1000 IU/m 2 in cohorts 1-3, IV) D1 &amp; D15 every 4 weeks (wk). Primary study endpoints were incidences of regimen limiting toxicities (RLT) and RP2D. Secondary endpoints included rate of composite complete remissions. Correlative studies included monitoring plasma amino acid levels and asparaginase activity, and expression of proteins regulating cap-dependent mRNA translation in bone marrow (BM) mononuclear cells pre- and post-VenPegC treatment. Results: As of July 31, 2023, 26 pts were enrolled of whom 24 received at least 1 dose of PegC and 17 completed at least 1 cycle of PegC (2 doses). The median age was 61 (range 24-79), 16 (62%) were female; 9 (35%) had CK-AML and 5 (19%) had TP53 mutations; 18 (69%) were previously treated with Ven. Median prior lines of treatment were 2 (range 1-5). No RLT was observed in cohort 1 (n=3). Cohort 2 was expanded to 6 pts due to transient asymptomatic hypertriglyceridemia. Two pts in cohort 3 (n=3) developed grade 3 hyperbilirubinemia determined as RLT. Expansion cohort included 11 pts who were treated at MTD/RP2D (PegC 750 IU/m 2 plus Ven 400 mg) given as out-pt without a need for hospitalization. No pancreatitis, thrombohemorrhagic events, or silent inactivation were observed in the entire study population. Overall response rate (ORR) for pts who received ≥1 cycle of PegC was 47% (8/17), Fig 1. CR+ CRh+CRi rate was 29% (5/17); 1 pt had a partial remission with full count recovery and is currently receiving cycle 6; 2 pts had stable disease. Four pts showed hematologic improvement. Twelve (71%) pts who received ≥1 cycle of PegC were previously treated with Ven and were Ven-refractory. ORR in Ven-refractory pts was 42% (5/12); of the 5 pts who harbored a RAS or PTPN11 mutation and previously treated with Ven, 60% responded. Remarkably, all pts (3/3) who had a RUNX1 mutation achieved a CR; Pt 6 (relapsed AML with NRAS/cKIT/RUNX1 mutations) achieved an MRD-negative CRh and underwent an allogeneic stem cell transplant (alloHSCT); Pt 12 (primary refractory AML with TP53/NRAS/RUNX1 mutations) achieved a clearance of BM blasts after 1 dose of PegC and achieved MRD-negative CR at the end of cycle 1, and Pt 15 (post-alloHSCT relapsed AML with NRAS/PTPN11/CSF3R/RUNX1 mutations) achieved a CRi and received 10 cycles of VenPegC. Pt 31 (post-alloHSCT relapsed AML with FLT3-ITD) who had persistent disease after gilteritinib achieved an MRD-negative CRi, pending 2 nd alloHSCT. Nadir plasma asparaginase activity of &amp;gt;0.1 IU/mL was achieved in cycle 1 for all pts who received ≥1 cycle of VenPegC. All pts with available results achieved undetectable asparagine (Asn) level by day 7 and Asn remained undetectable throughout the study. Plasma Gln reduction from baseline occurred in all pts (except 1) within cycle 1. Pts in cohort 1 reached nadir Gln after initial PegC exposure in an average of 22 days compared to 16 days in cohort 2. In general, pts who achieved CR had the lowest absolute plasma Gln levels. Available Glu and Gln are shown in Fig.1 for pts who achieved a CR/PR. Out of the 8 assessed pts (4 responders &amp; 4 non-responders), VenPegC inhibited cap-dependent translation after 1 cycle in responders, as evidenced by decreased phosphorylated eIF4E (active, pheIF4E) in 4/4 pts and decreased phosphorylated 4EBP1 (inactive, ph4EBP1), a negative regulator of eIF4E, in 2/4 pts. Conversely, pheIF4E and ph4EBP1 expression was increased in 3/4 and 4/4 of the non-responders, respectively (Fig.2). Conclusion: VenPegC is a novel regimen that can induce complete remission in some heavily pretreated R/R AML patients, even with previous exposure to Ven. Pts with RUNX1 mutation, whose translation depends on pheIF4E, may benefit further from this regimen.

Clonal Dynamics of FLT3-ITD Positive Acute Myeloid Leukemia Patients with Relapsed/Refractory Disease Following Intensive Chemotherapy +/- Midostaurin

Introduction: Despite the wider use of midostaurin (MIDO) in combination with intensive chemotherapy (ICT) as the 1st-line treatment for FLT3-mutated acute myeloid leukemia (AML), complete remission (CR) rates are close to 60%, and relapses occur in over 40% of cases, demonstrating the ability of leukemic cells to resist and evade therapy ( Stone et al., NEJM 2017). Conventional fragment-length analyses of paired diagnosis/relapse samples have shown that FLT3-internal tandem duplications (ITDs) are retained in 80% and 50% of cases following ICT alone and MIDO+ICT respectively ( Schmalbrock et al., Blood 2021). Only limited data are available on the dynamics of FLT3-ITDs or other co-mutations in refractory patients (pts). Here, we conducted a retrospective study involving 115 pts with relapsed/refractory AML harboring FLT3-ITD at diagnosis. Materials and methods: Clonal evolution was examined in paired diagnosis/progression blood or bone marrow samples from 115 pts with FLT3-ITD+ AML treated with MIDO+ICT (n=33) or ICT alone (n=82). Among them, 21 pts had primary refractory disease (MIDO+ICT, n=8; ICT, n=13) and 94 pts relapsed after achieving CR (MIDO+ICT, n=25; ICT, n=69). FLT3-ITDs and co-mutations were screened on genomic DNA by high-throughput sequencing at both timepoints using a custom-designed panel. For accurate annotation and quantification of FLT3-ITDs from sequencing data, we used the recentlypublished FiLT3r algorithm ( Boudry et al., BMC Bioinformatics 2022). For each ITD detected, FiLT3r allelic ratio (AR) was assessed by the ratio between the mutated allele and the wild-type allele. Results: A total of 226 FLT3-ITDs were detected in 115 pts at AML diagnosis, among which 120 (53%) ITDs were found with an AR below 0.05 ( Figure 1). Among pts who achieved CR and experienced relapse (n=94), 48 had multiple FLT3-ITDs at diagnosis and 46 had a single FLT3-ITD at diagnosis. Overall, we observed a simplification of the FLT3-ITD repertoire upon relapse with the persistence of at least one initial clone in 8/12 [67%] and 24/36 [67%] pts with multiple ITDs receiving MIDO+ICT and ICT alone respectively. In relapsed pts who initially had a single FLT3-ITD clone at diagnosis, the addition of MIDO to ICT was associated with a higher rate of FLT3-ITD negativity compared to pts receiving ICT alone (6/13 [46%] vs 5/33 [15%]; P = 0.05) ( Figure 2). Interestingly, among 21 pts with primary refractory AML, we observed that FLT3-ITD mutation status became negative in 5/8 pts (62%) and 2/13 pts (15%) after induction with MIDO+ICT and ICT alone respectively. We then compared the initial characteristics between retained and lost FLT3-ITDs at AML relapse. Lost FLT3-ITDs had significantly lower AR than retained clones in both treatment groups. In order to limit the impact of sample dilution on the allele burden, we defined adjusted variant allele frequencies (VAFs) as the VAFs of FLT3-ITDs normalized to the VAFs of NPM1 mutations, whenever applicable. In so doing, we observed that adjusted VAFs of retained FLT3-ITDs increased at relapse, regardless of the treatment group (adjusted VAF, diagnosis vs relapse: 0.28 vs 0.86 and 0.88 vs 1.6 in the MIDO+ICT group and ICT alone group; P = 2.3e-03 and P = 2.4e-04). Importantly, an adjusted VAF higher than 1 was strongly suggestive of a homozygous state of FLT3-ITD. Such situation was found to be more prevalent at relapse in both treatment groups. Besides the selection of a dominant FLT3-ITD clone, other relapse-related changes including the acquisition of additional mutations will be presented. Conclusion: Our study of the clonal dynamics of AML with FLT3-ITD mutations provides insights into the mechanisms underlying therapy escape. Our data suggest that clonal interference characterized by multiple FLT3-ITD clones is associated with a greater ability to select a FLT3-ITD-positive clone at relapse in pts receiving MIDO+ICT. Although the addition of MIDO to ICT increases the probability of eradicating a single FLT3-ITD clone, FLT3-ITD+ relapses remain common following this combination, often with the selection of homozygous FLT3-ITD clones and/or the emergence of new mutations. Finally, our data in refractory situation emphasize the need to reassess mutational status at each stage of progression before implementing targeted therapy.

Sequential Conditioning Regimen with Thiotepa, Clofarabine and Busulfan (TEC/CloB2A2) and Post-Transplant Cyclophosphamide in Adults with Refractory AML: A Retrospective Monocentric Study

Background : Since almost 20 years, sequential allogeneic stem cell transplantation is proposed to fit and relatively young patients with refractory hematologic malignancies (mainly acute myeloid leukemia (AML)) and who will otherwise die from the disease. This procedure is characterized by the use of a renforced conditioning regimen combining a debulking chemotherapy followed after 3 days of rest by the conditioning regimen itself. However, the results overall remain dismal as only a small proportion of patients are finally cured. Recently, a combination of thiotepa, etoposide, cyclophosphamide (TEC) followed by fludarabine/busulfan/ATG (FB2A2) using any type of donor for refractory hematologic malignancies have shown some promising results (Dulery, 2018). As clofarabine may have better antileukemic effect than fludarabine, we have investigated in our patients with refractory AML a new sequential approach combining TEC+clofarabine/busulfan/ATG (TEC/CloB2A2). Methods : We have investigated in our Hematology Department a new sequential conditioning regimen replacing fludarabine by clofarabine as part of a TEC/FB2A2 regimen with the hope to obtain less relapse and better survival in a cohort of patients with refractory AML. The TEC/CloB2A2 regimen consisted of Thiotepa 5 mg/kg at day(d)-13, Cyclophosphamide 400 mg/m²/d from d-12 to d-9 and Etoposide phosphate 100 mg/m²/d from d-12 to d-9, followed after 3 days of rest, by Clofarabine 30 mg/m²/d from d-5 to d-1, Busulfan 3,2 mg/kg/d d-5 and d-4 and Thymoglobuline 2,5 mg/kg/d d-3 and d-2. GVHD prophylaxis consisted of high-dose of post-transplant Cyclophosphamide (PTCY) 50 mg/kg/d at d+3 and d+5 in combination with mycophenolate mofetyl and cyclosporine starting at d+6. Any type of donor have been considered. Results : Between February 2020 and August 2022, 12 patients have been treated. Patient characterisitcs are given in the Table. Median age was 58 years (y) old. The majority of patients had primary refractory AML (n=9). This was the first transplant for all patients. One patient needed desensibilization before conditioning due to high level of anti-HLA antibodies directed against the donor. All but 2 donors were haploidentical. One patient with a matched donor did not receive PTCY after transplant. Two patients died during the aplasia phase, one at d+6 of sepsis and multiple organ failure (MOF) and one at d+30 of disseminated fungal infection. The median time of neutrophils (&amp;gt; 1 Giga/L) and platelets (&amp;gt; 50 Giga/L) recoveries were 22 days (range : 12-137) and 34 days (range : 16-241), respectively. There were no primary or secondary graft failures. Responses were evaluated at a median of 57 days (range : 26-70) after transplant. Five complete remission (CR), 3 CR with incomplete platelet recovery (CRp) and two failures were documented for an overall CR/CRp rate of 67%. Only one cutaneous grade 2 acute GVHD occured after transplant but no chronic GVHD. Six out of 8 CR/CRp patients received maintenance treatment after transplant to prevent relapse using 5'azacytidine alone in 1, 5 azacytidine+ donor lymphocyte infusion (DLI) in 2, DLI alone in 1. The last two patients received maintenance as part of a trial. The three patients receiving DLI developped acute GVHD thereafter including 2 grade 2 and one grade 3. Six of the patients achieving CR/CRp relapsed (75%) at a median of 160 days (range : 48-344) post-transplant. At last follow-up (July 2023), only one patient is alive in CR (8%) at 795 days from transplant (SET/CLoB2A2 +PTCY and sibling donor, grade 3 acute GVHD after DLI). Causes of deaths were relapse in 6, and infections in five (disseminated fungal infection n=1, COVID-19 n=2, bacterial infection + MOF n=1 and + distress respiratory syndrome n=1). Non-relapse mortality (NRM) was 25% and 41% at 1y and 2y, respectively. 1-y and 2y overall survival and leukemia-free survival were both at 25% (9.3-66.6) and 8.3% (1.2-54.4), respectively. Conclusion : The sequential TEC/CloB2A2 conditioning regimen is not associated with better outcomes compared to the TEC/FB2A2 sequential conditioning regimen. Other sequential approaches and/or GVHD/maintenance strategies have to be considered in the future for these very high-risk refractory AML patients in order to obtain better graft-versus-leukemia effect and lesser toxicity.

Comparison of Two Venetoclax-Based Regimens As Salvage Therapies Bridged to Allogeneic Hematopoietic Cell Transplantation in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Introduction ： Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment for relapsed or refractory acute myeloid leukemia (R/R-AML) patients. However, it is not clear about appropriate salvage therapy bridged to allo-HSCT for R/R-AML patients. In this study, we compared the outcomes of R/R-AML patients treated with venetoclax plus hypomethylating agents (VEN-HMA) regimen or venetoclax plus azacitidine and homoharringtonine (VAH) regimen as salvage therapies bridged to allo-HSCT. Methods ： A total of 105 R/R-AML patients treated with VEN-HMA regimen or VAH regimen bridged to allo-HSCT between September 2018 and February 2023 were enrolled. The outcomes including survival, relapse and NRM after allo-HSCT were analyzed in two groups. Results ： Forty-four patients were treated with VEN-HMA regimen, and 61 with VAH regimen. Seventy-four patients had primary refractory AML and 31 relapsed AML, including 19 relapsed after chemotherapy and 12 relapsed after allo-HSCT. Thirty-one (70.5%) patients achieved composite complete remission (CRc) in VEN-HMA group including 20 (45.5%) with minimal residual disease (MRD) negative, as well as 52 (85.2%) with CRc including 40 (65.6%) with MRD negative in VAH group (P=0.09). Twenty-five (56.8%) patients were stratified with adverse risk in VEN-HMA group and 45 (73.8%) in VAH group according to the 2022 European Leukemia Net (ELN) classification (P=0.07). The 2-year overall survival (OS) and event-free survival (EFS) in VAH group were higher (78.4% vs 58.7%, P=0.03; 68.3% vs 38.7%, P=0.003), as well as 2-year cumulative incidence of relapse (CIR) was lower than VEN-HMA group (23.2% vs 42.4%, P=0.04). Among patients with CRc, the 2-year OS, EFS and CIR was 67.5%, 48.9% and 37.0% in VEN-HMA group, as well as 82.5%, 72.5% and 23.6% in VAH group (P=0.15, 0.05 and 0.24). Among patients with MRD negative, the 2-year OS, EFS and CIR was 75.5%, 55.5% and 31.6% in VEN-HMA group, as well as 90.8%, 80.0% and 17.5% in VAH group (P=0.15, 0.10 and 0.28). Among patients with adverse risk, the 2-year OS and EFS in VAH group were higher (79.3% vs 47.7%, P=0.01; 70.9% vs 24.1%, P=0.0002), as well as 2-year CIR was lower than VEN-HMA group (17.4% vs 45.8%, P=0.01). Non-relapse mortality (NRM) was similar between VEN-HMA group and VAH group (18.9% vs 8.5%, P=0.12). Conclusion ： VAH regimen is an effective salvage therapy bridged to allo-HSCT for R/R-AML patients compared with VEN-HMA regimen. Keywords ： Venetoclax, Azacitidine, Homoharringtonine, Relapsed/Refractory AML, Allogeneic Hematopoietic Cell Transplantation.

A Phase 2 Study of Lenalidomide in Combination with Mitoxantrone, Etoposide, and Cytarabine (Len plus MEC) in Patients with Relapsed or Refractory Acute Myeloid Leukemia

Background: Outcomes for patients with relapsed or refractory acute myeloid leukemia (R/R AML) remain extremely poor. Response rates with salvage chemotherapy regimens, such as mitoxantrone, etoposide, and Cytarabine (MEC), have been associated with a complete remission rate of around 20-30%. We previously reported a phase I study combining Lenalidomide (Len) with MEC salvage chemotherapy, with encouraging response rates in R/R AML compared to other historical standards (DeAngelo et al. AJH 2018). This led to the current phase 2 study (NCT03118466) of Len combined with MEC in R/R AML to evaluate for the efficacy of this combination. Methods: We conducted a phase 2 study of Len plus MEC in adult patients (≥ 18 yrs) with R/R AML after 1 or more cycles of induction chemotherapy. Patients received Len dosed at 50mg/day on days 1-10, and Mitoxantrone 8mg/m2/d, Etoposide 100mg/m2/d and Cytarabine 1000mg/m2/d on days 4 through 8 of induction (Kohrt et al AJH 2010). Patients who achieved a complete remission (CR), complete remission with incomplete blood count recovery (CRi) or incomplete platelet recovery (CRp) could proceed with consolidation chemotherapy or hematopoietic stem cell transplantation at the discretion of the treating physician. The study followed a Simon two-stage design powered to detect improvement to a 45% response rate. The primary objective was to determine the response rate. Secondary objectives included time to neutrophil and platelet count recovery, treatment related mortality, rates of relapse, and overall survival. Results: A total of 40 patients were enrolled and received study treatment. The median age was 56 years (range, 19-70); 58% of the patients were male. 73% of patients had relapsed after initial therapy (29/40) while 27% had primary refractory AML (11/40) after their initial induction chemotherapy. The median number of prior therapies was 2 (range, 1-4). The majority of patients had adverse ELN 2023 risk (n=22; 55%). Recurrent gene mutations in 5 or more patients included DNMT3A (n=8), TET2 (n=7), NRAS (n=6), IDH2 (n=5), and ASXL1 (n=5); 2 patients harbored TP53 mutations. The most frequent grade 3-4 treatment-related toxicities were febrile neutropenia (n = 30; 75%), platelet count decrease (n = 40; 100%), anemia (n = 18; 45%), neutrophil count decrease (n = 14; 34%), blood bilirubin increase (n=6, 14%), and anorexia (n = 5; 12%). Three patients (8%) died during the study treatment period, all secondary to hepatic failure; no other early deaths occurred. Two of these patients had baseline grade 1 bilirubin elevation (no other patients in the study reported baseline bilirubin elevations). Median follow-up was 21 months. The overall response rate was 50% (20/40) where 19 achieved CR while 1 achieved CRi. Of 20 responders, the median time to neutrophil count recovery was 28 days and to platelet recovery was 34 days. The median time to relapse was 22.6 months. The median overall survival (OS) of the entire cohort was 16 months (Figure 1). Conclusions: Len plus MEC was associated with a high response rate and improved OS in patients with R/R AML as compared to historical controls. The overall safety profile was similar to prior MEC chemotherapy trials but several patients did experience early hepatic toxicity. Overall these data support evaluating high-dose Len combined with MEC for patients with R/R AML in a randomized study.

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 &amp;gt;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.

The Occurrence of Infection and TP53 Mutation Are Risk Factors for Cardiovascular Toxicity of Acute Myeloid Leukemia Induction Therapy

Introduction: For almost 50 years,induction therapy (IT) is the standard of care for acute myeloid leukemia (AML) patients. Nevertheless, little is known about cardiovascular (CV) toxicity during IT. We aimed to describe CV events (CVE)occurring during IT and to identify clinical, hematological and molecular risk factors of such events. Methods: Two hundred and twenty-four patients of 18 years or more (median age 61 (51;67) years, 58% males), treated with ITbetween 2014 and 2021 were enrolled in this study. Two hundred and one (90%) received an anthracycline-based IT, the others received gemtuzumab ozogamicin as part of a clinical protocol research. Survival from the time from initiation of IT until death or until the initiation of the second course of therapy (either salvage regimen in case of primary refractory or relapsed AML, or intensive consolidation therapy in case of response) was considered. The primary endpoint was the time to occurrence of the first CVE after IT initiation, with death as a competing event. Multivariate analysis included significant covariate, identified by univariate models among initial characteristics and occurrence of infection (coded as time dependent covariate). Results: Hematological characteristics were as follows: European LeukemiaNet (ELN) 2022 risk of myelodysplastic neoplasm (MDS)/AML was low, intermediate and adverse in 13%, 29% and 58% of patients respectively. Main mutations encounters were: DNMT3A, FLT3, NPM1, TET2, NRAS, RUNX1, ASXL1, IDH2, PTPN11, BCOR, SRSF2, WT1 and TP53. Main CV risk factors were tobacco (36%), arterial hypertension (35%), obesity (24%), hyperlipidemia (22%), diabetes mellitus (11%). Baseline left ventricular ejection fraction (assessed by transthoracic echocardiography) was &amp;gt;45% in all patients, &amp;gt;55% in 95% of patients. Seventy-five patients (33%) presented a CVE during IT. Eighty-six percent of CVE were severe (grade 3 or more). Patients presenting CVE during IT were significantly older (p=0.02) and presented more often a past history of dilated cardiomyopathy (p=0.04), arterial hypertension (p=0.005) or dyslipidemia (p=0.005). At baseline, CVE patients presented a greater left auricle volume (p=0.005), higher tricuspid regurgitation grade (p=0.01), and more often a right ventricular dilatation or a significative valvopathy (respectively p=0.01 and p=0.03). There was no difference in CVE occurrence between patients treated with and without anthracyclin (p=0.2). Competing risk models identified the following adverse characteristic for the risk of first CVE, namely the occurrence of the first infectious event (Hazard ratio [HR]= 2.43, p=0.005), TP53 mutation (HR=1.79, p=0.04). No other clinical characteristics nor mutation (including TET2 and DNMT3A) were identified. Multivariate analyses demonstrated that TP53 mutation (HR=1.78, p=0.04) and occurrence of infection (HR=2.29, p=0.008) retained independent prognostic value, see Table 1. In a response stratified model, only TP53 mutation was a risk factor of first CVE (HR=2.46, p=0.008). Conclusions: CVE occurred in 33% of patients during IT and were severe. The major adverse role of onset of infection for CVE occurrence after IT could overcome the prognostic value of mutations usually associated with CV risk in the healthy population (i.e. TET2, DNMT3A, ASXL1, ...). TP53 mutation was the only molecular abnormality associated with CVE, in agreement with the increased risk of doxorubicin-induced cardiac toxicity in a mouse model of TP53 clonal hematopoiesis developed by Sano et al. These results suggest that TP53 mutated patients could benefit from careful CV monitoring and optimization of primary prevention treatment.

Bisantrene in Combination with Fludarabine and Clofarabine As Salvage Therapy for Adult Patients with Relapsed or Refractory Acute Myeloid Leukemia (AML)- an Open-Label, Phase II, Study

Background: Bisantrene (Bis), is a topoisomerase-II inhibitor with anthracycline-like activity, lower cardiotoxicity, and activity in patients (pts) with relapsed (rel)/primary refractory (PR) acute myeloid leukemia (AML) (Am J Hematol, 2021). Bis was also found to synergize with the cytotoxic purine nucleoside analogs clofarabine (Clo) and fludarabine (Flu) in vitro (J Clin Exp Oncol, 2021). We now conducted a phase II study combining Bis with Clo and Flu in pts with Rel/PR AML (NCT04989335). Methods: This was a phase II open-label single-center study with 2 stages: a stage with 3+3 dose escalation to assess the safety and provide phase 2 dose (RP2D, 4 vs 5 days) of infusion (i.v.) with up to 12 pts and an expansion phase with up to 17 pts (Simon 2-stage design 9+8) to assess the primary efficacy and confirm the safety of f Bis/Clo/Flu combination pts with Rel/PR AML. Flu (10 mg/m 2) was administered i.v. over 1 hour (h), followed by a 1-h infusion of Clo (30 mg/m 2), and then a 2-h infusion of Bis at 250 mg/m 2, with a 1-hour break for 4 days. The primary endpoint was achieving a partial response (PR). Efficacy was assessed by bone marrow (BM) examination 21 - 30 days post-therapy. Safety included treatment-emergent adverse events (TEAEs), all-cause mortality, and cardiac monitoring with ECG and troponins Toxicity was assessed as per Common Terminology Criteria for Adverse Events (CTCAE v5.0). Interim analysis was planned after the first 12 pts. Results: 20 pts were included from August 2021. The median age was 48 (19-69) years and 55% were male.14 pts had de novo AML and 5 had secondary AML, 11 pts were in rel, while 9 had PR disease. Median lines of therapy were 4(3-9), 12 with ≤ 4 and 8 &amp;gt;4 lines of therapy. All pts were refractory to the last line of therapy.15 pts (75%) were in relapse post allogeneic transplantation (HSCT). 5 (25%) pts had active extramedullary disease (EMD, 1 with CNS involvement). Median bone marrow blasts pre-Bis/Clo/Flu treatment was 50%. Cytogenetic was normal in 10 (50%) of the pts, 5 had a complex karyotype, 2 MLL rearrangements, 1 t8; 21 and 2 pts had other chromosomal abnormalities. The maximum tolerated dose of the Bis/Clo/Flu combination was 4 days of infusion due to grade 3 liver toxicity in 2 pts and 1 pt that died from sepsis in the first stage of the study. Overall 10 pts developed liver toxicity with elevated liver enzymes and bilirubin in 9 of them (grade 1-4 pts; grade 2-3 pts and grade 3-3 pts). Liver toxicity was transient and resolved in all pts. Two pts had treatment interruption due to liver toxicity. 4 pts had grade I renal toxicity, 7 had mild fluid retention, and 18 developed neutropenic fever of which 10 pts had verified bacteremia. Five pts had pneumonia, 4 invasive fungal infections, and 2 sepsis (1/2 died).1 additional pt died from cerebral venous sinus thrombosis. Overall 5 pts died early and could not be evaluated for response. Clinical-relevant cardiac toxicity was not observed in any of the pts and no one developed ECG changes Transient grade 1 elevation of troponin levels was observed in 4 pts. Six pts responded (CR-5, PR-1) 3 with EMD, however, responses were short-lived and lasted up to 3 months. Five pts (responding-4, active disease-1, being the second transplant in 4) underwent HSCT 1-3 months post-Bis/Clo/Flu with reduced /intermediate intensity conditioning. Stem cell donors were haploidentical-2, matched unrelated -1, and matched sibling-2, respectively. Three pts died: one from graft versus host disease and the other from relapse within 4 months post-transplant and the third from sepsis 2 years post-HSCT. Two of the transplanted pts are in complete remission with a 2-month follow-up. Conclusions : In this Phase II study in a very advanced group of relapsed refractory AML ptsresistant to multiple previous lines of chemotherapy including transplantation and with a median of 50% blasts at study initiation, Bis/Clo/Flu combination therapy was found to be safe and well tolerated without cardiac toxicity or tumor lysis syndrome. The maximum length of Bis/Clo/Flu administration was 4 days due to rapidly reversible liver toxicity, and transaminitis. As expected in this highly pretreated population, the infection rates were high. Six /15 evaluable pts (40%) respond, enabling an HSCT in 5 of them. These rather impressive results in such a heavily pretreated population support further studies of Bisantrene-based combinations, including those with venetoclax or hypomethylating agents.

Non-T-Depleted Haploidentical Transplantation with Post-Transplant Cyclophosphamide in Patients with Relapsed/Refractory Secondary Versus De Novo AML: A Study from the ALWP/EBMT

Background: Secondary acute myeloid leukemia (sAML) is a distinct type of AML. Transplantation, a potentially curative therapy, outcomes are inferior compared to de novo AML. We recently demonstrated (J Hematol Oncol 2023) that results of non-T-cell depleted haploidentical stem cell transplantation (HaploSCT) with post-transplant cyclophosphamide (PTCy) in sAML in complete remission are not significantly different from those in denovo AML. However, the challenge in relapse (Rel)/primary refractory (PR) AML is much higher. Methods:The study aim was to compare the outcomes of HaploSCT with PTCy, performed between 2010 and 2022, in first Rel(Rel1)/PR sAML versus those in Rel1/PR de novo AML. Statistical tests included a multivariate analysis (MVA) adjusting for potential confounding factors using a Cox proportional-hazards regression model for main outcomes. Results: A total of 719 patients (pts) met the inclusion criteria, 129 with sAML and 590 with de novo AML. Median follow-up was 45.6 (IQR] 39.1-57.9) and 43.5 (IQR, 37.5-48.0) months for pts with sAML and de novo AML, respectively (p=0.20). Pts with de novo AML were younger, with a median age of 55.4 (range 18-77.8) versus 61.3 (21-78.8) years, (p&amp;lt;0.0001). The median year of the transplant was 2018 (2010-2011) in pts with sAML and 2017 (2010-2022) in those with de novo AML (p=0.62) and 65.1% and 57.6%, were male (p=0.11). In 81.4% of sAML pts, the antecedent hematological disorder was myelodysplastic syndrome. The cytogenetic risk was categorized as intermediate (58.6% vs 59.4%), adverse (37.4% vs 34.7%), and favorable (4% vs 5.9%) for pts with sAML and de novo AML, respectively (p=0.75) (data missing for 145 pts). A higher percentage of pts with sAML vs de novo AML had PR disease (73.6% vs 58.6%) (p=0.002). HCT-CI was higher in the sAML vs the de novo AML group, with HCT-CI &amp;gt;3 in 40.3% vs 21.9%, respectively (p&amp;lt;0.0001), while the Karnofsky performance status (KPS) did not differ. There was no difference in the frequency of cytomegalovirus (CMV) seropositivity and female donor to male pt combination between the two pt groups. Reduced intensity conditioning was received by 60.2% and 52.2% of the sAML and de novo AML pts, respectively (p=0.1), with thiotepa/busulfan/fludarabine being the most frequent regimen for both groups (38.8% vs 42%, respectively). Graft source was mainly peripheral blood stem cells (PB) in both sAML (69.8.5%) and de novo (66.8%) groups. All pts received PTCy as graft- versus-host disease (GVHD) prophylaxis in combination with immunosuppression, which was cyclosporine A (CSA)/ mycophenolate mofetil in 41.1% vs 52.9% and CSA/tacrolimus in 41.1% vs 33.6% respectively. Cumulative incidence of absolute neutrophil count (ANC) &amp;gt;0.5 x 10 9/L at day 60 was 83.5% vs 88.4% (p=0.13), respectively. Day 180 incidence of acute (a) GVHD II-IV and III-IV was 20% vs 26.9% (p=0.12) and 8.9% vs 10.4%, (p=0.21), respectively. The 2-year (y) total and extensive chronic (c) GVHD were 25.3% vs 20.7% (p=0.27) and 12.5 % vs 10.3% (p=0.46), respectively. In MVA HaploSCT outcomes did not differ significantly between the Rel1 /PR sAML and de novo groups; 2-y non-relapse mortality (NRM) hazard ratio (HR)=1.38 (95% CI 0.96-1.98, p=0.083). Infections and GVHD were the cause of death in 20.8% and 9.3% of pts who died. The HR for 2-y relapse incidence (RI) was 0.68 (95% CI 0.4.7.-1.00, p=0.051) and RI was the main cause of death in 40.9% and 59.3% of pts who died, respectively. The 2-y leukemia-free survival (LFS), overall survival (OS), and GVHD-free, relapse-free survival (GRFS) did not differ between the two groups with HR=0.99 (95% CI 0.76-1.28, p&amp;lt;0.94), HR=0.99 (95% CI 0.77-1.29, p=0.973) and HR=0.99 (95% CI 0.77-1.27, p=0.94), respectively. Adverse-risk cytogenetics was a poor prognostic factor for RI and both higher age (per 10y) and lower KPS were poor prognostic factors for NRM. Adverse-risk cytogenetics and lower KPS were poor prognostic factors for LFS, OS, and GRFS. In addition, pt CMV seropositivity was a poor prognostic factor for OS. Finally, PB grafts were associated with increased risk of all grades and severe aGVHD. Conclusions: In this registry-based retrospective analysis, we observed similar outcomes, of HaploSCT with PTCy for Rel1/PR sAML compared to Rel1/PR de novo AML, with HaploSCT being able to rescue about one-third of the pts. However, relapse is still 43%. The recently approved novel agents for sAML will hopefully further improve sAML outcomes.

Preliminary Safety and Efficacy of Venetoclax and Selinexor in Combination with Chemotherapy in Pediatric and Young Adult Patients with Relapsed or Refractory Acute Myeloid Leukemia: Selclax

Background: Survival rates for children and adolescent/young adults (AYAs) with relapsed or refractory acute myeloid leukemia (R/R AML) remain poor. Previous clinical trials have demonstrated that the selective inhibitor of nuclear export selinexor and the BCL2 inhibitor venetoclax are each safe and active when combined with chemotherapy in children with R/R AML (NCT02212561, NCT03194932). However, many patients are refractory to these combinations. Preclinical data indicate that selinexor and venetoclax are synergistic and that selinexor may abrogate resistance to venetoclax. We thus aimed to characterize the toxicity profile and explore preliminary activity of venetoclax and selinexor with chemotherapy in pediatric and AYA patients with R/R AML and report results from the dose escalation phase of the SELCLAX clinical trial (NCT04898894). Methods: SELCLAX is a Phase I and expansion cohort study of selinexor and venetoclax in combination with chemotherapy in pediatric and AYA patients with R/R AML. For the dose escalation phase, eligibility criteria included &amp;lt; 30 years of age, adequate organ function and performance status, primary refractory, early first relapse (&amp;lt; 12 months from initial diagnosis), relapsed and refractory to salvage, post-transplant relapse or second or greater relapse AML or acute leukemia of ambiguous lineage (ALAL). The primary endpoint was determination of the recommended phase 2 dose (RP2D) of venetoclax and selinexor with chemotherapy. In the dose level 1 (DL1) cohort, venetoclax was given at 360 mg/m 2 per dose (max 600 mg) on days 1-21 in combination with selinexor at 40 mg/m 2 on days 1, 8, 15. For dose level 2 (DL2), venetoclax was dosed as in DL1, and selinexor was dosed at 40 mg/m 2 twice weekly on days 1, 3, 8, 10, 15, 17. Chemotherapy (fludarabine 30 mg/m 2, cytarabine 2 g/m 2 ± granulocyte colony stimulating factor 5 mcg/kg [FLA(G)]) was given on days 16-20. Response was evaluated by blast percentage in day 8 and 15 peripheral blood and in day 15 and end-cycle bone marrow. Any patient with a two-log (100-fold) reduction in measurable residual disease (MRD) between baseline and Day 15 was designated an “exceptional responder” (ER). At the discretion of the treating physician, ER patients could continue venetoclax until day 28 with additional selinexor (DL1: day 22; DL2: day 22, 24); FLA(G) could either be omitted or given on days 30-34; omission of FLA(G) deemed a patient non-evaluable (NE) for dose-limiting toxicity (DLT). Evaluable patients were assessed for DLTs, and dosing was escalated according to a rolling-six design. Results: As of July 14, 2023, fifteen patients (aged 3-17 years) with R/R AML (n=14) or ALAL (n=1) were enrolled in the dose escalation phase ( Table 1). Nearly all patients had high-risk cytomolecular features: KMT2A-rearranged (n=5), NUP98-rearranged (n=5), -7/del(7) (n=3), or FUS::ERG (n=1). Seven patients were enrolled on DL1 (one NE, replaced); eight patients were enrolled on DL2 (two NE, replaced). In the DL1 cohort, one DLT was reported of grade 3 anorexia requiring nasogastric feeds; however, this was cofounded by a prior history of anorexia, mucositis, and poor dentition requiring extractions and restorations. At DL2, one patient experienced a hematologic DLT with failure to recover absolute neutrophil count above 500/uL and platelet count above 25,000/uL by day 43 from start of FLA(G). There were no DLTs in the other five evaluable patients in DL2 and no serious adverse events (AEs) reported. The most common Grade 3 or 4 AE was febrile neutropenia (16.7%). Of the evaluable patients, five of twelve (41.7%) achieved complete response (CR) or complete response with incomplete count recovery (CRi). One patient was an ER on Day 15 at DL2 and did not receive FLA(G); thus, this patient was not evaluable for DLT assessment. Six patients proceeded to hematopoietic cell transplant after protocol therapy, five of whom are alive to date. Conclusion: Venetoclax and selinexor with FLA(G) chemotherapy is a tolerable combination in pediatric and AYA patients with R/R AML. Early activity of this combination regimen was observed in some patients, including those with primary refractory or early first-relapsed AML. Enrollment of the dose expansion phase at DL2 is underway in two cohorts: venetoclax-naïve and venetoclax-exposed.

AML-025 Clinical Relevance of the RUNX1 Mutation in Egyptian Patients With Primary Refractory Acute Myeloid Leukemia

AML-025 Clinical Relevance of the RUNX1 Mutation in Egyptian Patients With Primary Refractory Acute Myeloid Leukemia

POSTER: AML-025 Clinical Relevance of the RUNX1 Mutation in Egyptian Patients With Primary Refractory Acute Myeloid Leukemia

POSTER: AML-025 Clinical Relevance of the RUNX1 Mutation in Egyptian Patients With Primary Refractory Acute Myeloid Leukemia

Phase 1B/2A safety, pharmacokinetics and pharmacodynamics study of fosciclopirox alone and in combination with cytarabine in patients with relapsed/refractory acute myeloid leukemia.

TPS7078 Background: Fosciclopirox (CPX-POM) is a broad-spectrum anticancer agent being developed through a public-private partnership between CicloMed LLC and KU Cancer Center (KUCC). Following intravenous administration, fosciclopirox is rapidly and completely metabolized to its active metabolite ciclopirox (CPX). Given fosciclopirox is a prodrug lacking pharmacologic activity, in vitro mechanistic studies were conducted utilizing CPX as the test article. In collaboration with Notable Labs (Foster City CA), we characterized ex vivo sensitivity to CPX in bone marrow and peripheral blood samples from ten newly diagnosed and relapsed acute myeloid leukemia (AML) patients. Reductions in blast counts were seen in each of the 10 patients studied at clinically relevant concentrations. In vitro experiments in AML cell lines (HL-60 and MV4-11) characterized the mechanism(s) of the anti-leukemia activity of CPX. CPX inhibited proliferation of AML cell lines in a dose- and time-dependent manner with IC50 values ranging from 2.5-4 µM. CPX induced cell cycle arrest in the subG0 phase and CPX-treated cells lost their ability to enter to G0-G1 phase. Moreover, CPX induced early and late phase apoptosis. CPX also activated Caspase 3/7 activity. This preclinical data led to the development of a multi-center Phase 1B/2A clinical proof of concept trial (NCT04956042) in AML patients. Methods: Eligible AML patients are adults with primary refractory (two prior regimens) or relapsed AML; ECOG PS 0-2; adequate end organ function. Prior allogeneic stem cell transplant is allowed if patient is more than 100 days post-transplant with no active graft-versus-host disease. CPX-POM is administered as 900 mg/m2 once daily as an IV infusion on Days 1 to 5 of each 21-day cycle. Day 8 bone marrow sample is collected for correlative studies. Ex vivo Drug Sensitivity Screening (DSS) will be performed on samples obtained prior to treatment and C1 Days 8 and 21. 14 evaluable patients will be enrolled in Cohort 1a. If disease response is observed in at least 4 of 14 patients, an additional 14 patients will be enrolled in Cohort 1b. During Cohort 1a, patients who do not respond to CPX-POM alone may be switched to the combination of CPX-POM + cytarabine. Patients who respond to the combination treatment may continue until evidence of disease progression. If disease response to CPX-POM alone is not observed in at least 4 of 14 patients in Cohort 1a, the study may be terminated or a Cohort 2a may be initiated using the combination of CPX-POM and cytarabine. The trial is currently open at two sites with 14 patients enrolled and 8 evaluable for the primary endpoint. Clinical trial information: NCT04956042 .

Outcomes of adult patients with type 1 primary refractory acute myeloid leukemia: a single center experience

ABSTRACTAdult patients with newly diagnosed de novo acute myeloid leukemia (AML), who had less than a 50% reduction in blast numbers and with > 15% residual blasts after first cycle of induction chemotherapy, defined as type 1 primary refractory (REF1), have grave prognosis. We retrospectively analyzed the data of 58 patients with REF1 who received salvage treatments with curative intension to evaluate the impact of salvage regimens with regard to response and overall survival (OS). Seventeen patients received intermediate- or high-dose cytarabine (ID/HD Ara-C) based intensive salvage chemotherapy, 36 patients received G-CSF primed less intensive chemotherapy and 5 patients received novel targeted drugs based low intensive therapy. The CR/CRi and MLFS rate was 6/17 and 2/17, 14/36 and 3/36, 3/5 and 0/5, respectively. The median OS for the whole cohort was 20.3 months. Median OS was comparable between the 3 arms. Overall, 42 patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), 14 patients in the intensive arm, 24 patients in the less intensive arm and 4 patients in the low intensive arm. Median survival for allo-HSCT patients was significantly longer than for non-allo-HSCT patients (38.8 months vs. 2.1 months, p < 0.001). In multivariate analysis, achievement of CR/CRi after the salvage regimen were predictive of OS. We conclude that no significant difference in outcome among traditional salvage regimens in patients with REF1. G-CSF primed less intensive chemotherapy could serve as an alternative of ID/HD Ara-C based intensive chemotherapy and allo-HSCT is indispensable for long-term survival.

Venetoclax Combined with Azacitidine and Homoharringtonine in Relapsed/Refractory AML: A Multicenter, Phase 2 Trial

BackgroundRelapsed or refractory acute myeloid leukemia (R/R AML) has a dismal prognosis. The aim of this study was to investigate the activity and tolerability of venetoclax combined with azacitidine plus homoharringtonine (VAH) regimen for R/R AML.MethodsThis phase 2 trial was done at ten hospitals in China. Eligible patients were R/R AML (aged 18–65 years) with an Eastern Cooperative Oncology Group performance status of 0–2. Patients received venetoclax (100 mg on day 1, 200 mg on day 2, and 400 mg on days 3–14) and azacitidine (75 mg/m2 on days 1–7) and homoharringtonine (1 mg/m2 on days 1–7). The primary endpoint was composite complete remission rate [CRc, complete response (CR) plus complete response with incomplete blood count recovery (CRi)] after 2 cycles of treatment. The secondary endpoints include safety and survival.ResultsBetween May 27, 2020, and June 16, 2021, we enrolled 96 patients with R/R AML, including 37 primary refractory AML and 59 relapsed AML (16 relapsed after chemotherapy and 43 after allo-HSCT). The CRc rate was 70.8% (95% CI 60.8–79.2). In the patients with CRc, measurable residual disease (MRD)-negative was attained in 58.8% of CRc patients. Accordingly, overall response rate (ORR, CRc plus partial remission (PR)) was 78.1% (95% CI 68.6–85.4). At a median follow-up of 14.7 months (95% CI 6.6–22.8) for all patients, median overall survival (OS) was 22.1 months (95% CI 12.7–Not estimated), and event-free survival (EFS) was 14.3 months (95% CI 7.0–Not estimated). The 1-year OS was 61.5% (95% CI 51.0–70.4), and EFS was 51.0% (95% CI 40.7–60.5). The most common grade 3–4 adverse events were febrile neutropenia (37.4%), sepsis (11.4%), and pneumonia (21.9%).ConclusionsVAH is a promising and well-tolerated regimen in R/R AML, with high CRc and encouraging survival. Further randomized studies are needed to be explored.Trial registration clinicaltrials.gov identifier: NCT04424147.