Mutations Highly Specific for Secondary AML Are Associated with Poor Outcomes in Patients with NPM1-Mutated ELN Favorable Risk AML

Background: NPM1 is commonly mutated in acute myeloid leukemia (AML) and represents a distinct entity under the WHO 2016 classification. It is one of the few mutations that can potentially support favorable risk by European LeukemiaNet (ELN) 2017 criteria. Mutations that are highly specific for secondary AML including SRSF2, SF3B1, U2AF1, ZRSR2, ASXL1, EZH2, BCOR, and STAG2 (sMut) (Lindsley et al.) have been shown to confer poor prognosis. The impact of these mutations on NPM1-mutated AML warrants further investigation. Objective: In this study, we explore the outcomes in patients with NPM1-mutated AML. Methods: This was a retrospective study of NPM1-mutated AML patients who were diagnosed and treated at the Moffitt Cancer Center from 2013 to March 2021. Inclusion was restricted to NPM1-mutated patients with mutation analysis (NGS) performed at diagnosis (n=159). Kaplan-Meier, univariate, and multivariate analyses were performed. Results: Among 159 patients (78M/81F, median age 63 years at diagnosis), 80.5% had de novo AML. By ELN 2017 criteria, 63.5% (101/159) had favorable risk, 27.7% (44/159) had intermediate risk, and 8.2% (13/159) had adverse risk disease. Almost 90% had intermediate risk cytogenetics at the time of diagnosis. Common co-mutations included DNMT3A (47.2%), FLT3-ITD (35.8%), TET2 (26.4%), IDH1 (17.6%), FLT3-TKD (15.1%), and IDH2 (13.8%). sMut comprised 19.5% (31/159) of patients and 20.8% (21/101) of those with ELN favorable risk. In patients with treatment response data, those with sMut never achieved CR/CRi in 35.7% (10/28) compared to 17.2% (22/128) of patients without sMut (p=0.038). The overall survival (OS) was 43.7 months with a median follow up of 35.5 months. Patients with sMut had worse OS compared to those without sMut (14.7 months vs 57.6 months, p=0.011). Among patients with favorable risk disease, OS was 11.6 months compared to not reached for those with sMut and without sMut, respectively (p<0.0001). Univariate analysis showed sMut and allogeneic hematopoietic cell transplant (HCT) significantly impacted OS (sMut: HR 3.48, 95% CI: 1.80-6.72, p<0.001; HCT: HR 0.17, 95% CI: 0.07-0.44, p<0.001). Multivariate regression using covariates including age, AML type, sMut, and HCT confirmed their prognostic significance on survival (sMut: HR 2.40, 95% CI: 1.17-4.93, p=0.017; HCT: HR 0.26, 95% CI: 0.08-0.56, p=0.002). Conclusions: Our findings suggest NPM1-mutated AML patients with sMut have significantly worse prognosis despite being classified primarily as favorable risk by ELN 2017 at diagnosis. This may have treatment implications altering the need for and/or timing of HCT. These findings should be assessed prospectively and validated in independent datasets. Figure 1 Figure 1. Disclosures Hussaini: Adaptive: Consultancy, Honoraria, Speakers Bureau; Stemline: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy; Celegene: Consultancy; Decibio: Consultancy; Guidepoint: Consultancy; Bluprint Medicine: Consultancy. Talati: AbbVie: Honoraria; Pfizer: Honoraria; Astellas: Speakers Bureau; BMS: Honoraria; Jazz: Speakers Bureau. Kuykendall: Incyte: Consultancy; Novartis: Honoraria, Speakers Bureau; Protagonist: Consultancy, Research Funding; Celgene/BMS: Honoraria; Abbvie: Honoraria; Blueprint: Honoraria; Pharmaessentia: Honoraria. Padron: Blueprint: Honoraria; Incyte: Research Funding; Kura: Research Funding; Stemline: Honoraria; Taiho: Honoraria; BMS: Research Funding. Sallman: Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Magenta: Consultancy; Takeda: Consultancy; Kite: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Intellia: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding. Sweet: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees. Komrokji: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Geron: Consultancy; BMSCelgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Acceleron: Consultancy; AbbVie: Consultancy; Jazz: Consultancy, Speakers Bureau; Taiho Oncology: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Membership on an entity's Board of Directors or advisory committees. Lancet: AbbVie: Consultancy; Celgene/BMS: Consultancy; Daiichi Sankyo: Consultancy; ElevateBio Management: Consultancy; Millenium Pharma/Takeda: Consultancy; BerGenBio: Consultancy; Jazz: Consultancy; Agios: Consultancy; Astellas: Consultancy.

CPX-351 for Acute Myeloid Leukaemia: Real World Results Are Comparable to Trial Outcomes and Exceeds Them in Non-Adverse Risk Patients- a Multicentre Experience from West Midlands Hospitals on Behalf of West Midlands Research Consortium ( WMRC) UK

Patients with secondary AML or MDS derived AML have poor outcomes compared to de-novo AML. The benefits of intensive chemotherapy without anticipated transplant consolidation have been previously doubted. Outcomes in USA trial centres have not often been closely replicable in real world settings. From November 2018 CPX-351 has been available in the UK for secondary AML, therapy related AML, AML with MDS related Karyotype (AML-MRC) and licensed but not funded for AML with myelodysplastic related changes. Objectives Here we report our experience specifically on patient outcomes and toxicity across 5 Hospitals in West Midlands, UK Methods Patients receiving CPX 351 outcomes were evaluated retrospectively from 2018 to 2021. Baseline genetics, CPX 351 indications, patient's comorbidities, overall survival, remission status, number of cycles delivered, early mortality, reasons for early discontinuation, intensive care admission and time for neutrophil recovery (>0.5) was recorded. Time-to-event outcomes reported here are from a data cut on 01-06-21 Results In a total cohort of 57 patients baseline characteristics are shown on table 1 and compared with the original trial CPX-351 group. Median follow up was 376 days (range 21 to 1248 days). The mean age was 63, 17 patients were under 60, 31 males and 26 females. The most common indication for CPX-351 was AML with antecedent MDS/MPN 51% (N=29), therapy related 14% (N=8), MDS related karyotype (AML-MRC) 19% (N=11) and 16% (N=9) other patients. Mean Charleston co-morbidity score was 2.7 (range 0-6), 10.5% (N=6) had previous non myeloid malignancies, 8.7% (N=5) had prior ischaemic heart disease, only 3.5% (N=2) had ejection fractions under 50%. The most common mutations were TP53 21% (N=12), ASXL1 15.7% (N=9), TET2 15.7% (N=9), IDH2 10.5% (N=6), RUNX1 10.5% (N=6), SRSF2 7% (N=4), JAK2 3.5% (N=2), FLT3 5% (N=3), NPM1 5%(N=3) and IDH1 5% (N=3). MRC cytogenetic risk was adverse in 19 patients (33%), intermediate in 35 patients (61%) and favourable in 3 patients (5%). 30 patients (53%) had adverse European Leukaemia Network classification, 17 (30%) had intermediate and 10 (17%) had favourable. 30-day mortality was 3/57 (5%), 60-day mortality was 6 (10.5%) comparable to the 5.9% and 10.6% rates for the original trial. 9% or 5/57 patients were admitted to ITU with 2 survivors beyond 60 days. Neutropenic fever requiring antibiotics was 100% whereas only 5/57 (9%) had radiological evidence of fungal infection. Only one patient died from COVID 19. The mean time to neutrophil recovery was 35 days with a range of 12 to 84 days. 29 patients completed 1 cycle, 25 completed 2 cycles, only 3 completed 3 cycles. The reasons for stopping were death, refractory disease, drop in performance status, alternative chemotherapy chosen or moving to transplantation (39%). Composite remission rate including CRi was 61% 36/57, adverse ELN group demonstrated 50% 15/30, intermediate 76% 13/17 and favourable 80% 8/10. Mutated P53 was associated with a 50% 6/12 rate whereas in wild type P53 the remission rate was 60% 30/45. Overall median survival from diagnosis was 429 days [95% CI 274 to 788 days]. To compare with the original trial, we removed the under 60s and those with less than 1 year follow up, in this cohort of 30 patients the median survival was 289 days (9.5 months) with 95% CI of 255 to 476 days. P53 mutated patients had an estimated median survival of 257 days versus wild type p53 with 524 days hazard ratio of 2.418 (CI 1.077 to 5.248) with p value of 0.032. Median survival for ELN groups was 373 days (adverse), 413 days (intermediate) and not reached for favourable. Of the 36 patients who achieved a remission, 22 went on to receive an allogenic transplant with follow from 254 to 1248 days, median survival estimated 706 days (95% CI 429-not reached). Patients in remission who haven't received a transplant have a similar estimated survival of 788 days (305-not reached) pending longer follow up. Conclusion This is the first UK multicentre analysis to show comparable results to the landmark trial (median survival 9.5 months in equivalent cases). The improved overall remission rate 61% versus the 47% in the trial and the longer median survival 14 months versus 9.5 months in the trial is expected given the younger age and increase in favourable risk genetics. This study therefore supplies further data of CPX-351 efficacy in younger patients not included in the original studies and may now be used as a standard comparator arm. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Germline and Somatic Variants of CSF3R Define Distinct Myeloid Neoplasia Syndromes

Somatic and germline (GL) variants of CSF3R are found in myeloid neoplasia (MN) and severe congenital neutropenia (SCN). In particular, somatic gain-of-function mutations in the juxtamembrane region of the receptor occur in chronic neutrophilic leukemia (CNL) or secondary AML. Another hotspot for somatic nonsense variants frequently mutated in these categories of pts involves the intracellular domain which regulates inhibitory growth pathways. We hypothesized that the somatic CSF3R variants could reveal previously unrecognized GL SCN mutations. When we studied a cohort of 2,610 pts with MN, we identified a total of 68 CSF3R variants (CSF3RMT). Using a bioanalytic pipeline, we assigned pathogenicity and type of origin (somatic vs. GL) to these variants, particularly those not previously described. In total, we found 32 GL (CSF3RGL) and 36 somatic (CSF3RS) mutations. Of the GL variants, 4 were previously described in pts with SCN consistent with heterozygous loss of function of the CSF3R gene. However, 15 additional alterations were located in similar regions and were predicted to be pathogenic while 13 variants were previously never described. Most of the CSF3RGL mutations were identified in pts with AML and MDS (88%). Interestingly, 2 (6%) pts had co-existing idiopathic neutropenia that progressed to secondary MDS. Another pt had aplastic anemia that eventually progressed to secondary AML. CSF3RGL were most often located in either the intracellular domain (44%) or the extracellular domain (34%) while none of the CSF3RGL mutations were found in the juxtamembrane region (Fig1). AML was detected in 21% of the pts with a CSF3RGL intracellular domain mutation and 18% of the pts with extracellular domain mutations. Of the germline missense variants, E808K (28%), R698C (9%), and E149D (9%) were the most frequently detected. Among the pts with E808K, 22% developed AML. The previously non-reported variants were detected in either the intracellular (50%) or the extracellular domain (50%). Missense variants were detected in 9/10 of the novel mutations in the following locations: L723V (20%), R428K (10%), G731R (10%), V406fs (10%), G687S (10%), P682H (10%), T154I (10%), and S413L (10%). One truncating mutation was found (c.1865-6delC) and it was located in intron 14 and has unknown impact on CSF3R function. Complex karyotype was noted in 19 % of the cases with CSF3RGL. DNMT3A (19%), NRAS (13%), FLT3 (9%), and BCOR (9%), were the most commonly found co-mutations. CSF3R S mutations were all heterozygous and found in 18 pts with AML and 18 pts with MDS and other MN. Overall, these lesions mapped within the intracellular proximal and distal domains (53%), the extracellular domain (14%) the juxtamembrane domain (25%), and the transmembrane domain (8%). Of note, MDS/MPN pts with CSF3RS mutations (11%) had lesions distributed between the intracellular, juxtamembrane and extracellular domains while none of the AML pts had mutations in the extracellular domain. Of all mutations, 36% were truncating events previously described in the context of post SCN AML while 61% were missense mutations. T618I was the most frequent CSF3RS detected (25%), followed by Q749X (11%), Q741X (9%), Q743X (6%). Juxtamembrane hits (CNL-like lesion) were all in the same canonical region (T618I). In contrast, somatic hits otherwise typical for post SCN AML were found in 33% of CSF3RS alterations and included the following: Q749X(4), Q741X (3), Q739X (2), S742X, Q743X, and E405K (not typical for post SCN AML). Taken together the combined allelic burden of these variants did not exceed that of general population (OR: 0.9503) suggesting that they are not significant risk alleles. Of note is that none of these variants were found to be in biallelic (somatic/GL) configurations. Complex karyotype was found in 19% of the pts with CSF3RS followed by del7q in 13% of cases. Importantly, an antecedent history of neutropenia was noted only in 14% of the pts carrying CSF3RS. Regarding associated mutations, ASXL1 (43%), RUNX1 (23%), SETBP1 (23%), TET2 (23%), DNMT3A (17%), SRSF2 (16%), EZH2 (14%), IDH2 (11%), and NRAS (11%) were the most common co-mutations. We have investigated CSF3RS mutations for the presence of GL alterations, but compound heterozygous configurations were not identified. We concluded that CSF3R mutations typically associated with SCN transformation to myeloid neoplasia can occur without GL variants associated with this defect. Figure 1 Figure 1. Disclosures Balasubramanian: Servier Pharmaceuticals: Research Funding. Patel: Apellis: Consultancy, Other: educational talks, Speakers Bureau; Alexion: Consultancy, Other: educational talks, Speakers Bureau. Advani: Kite Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Glycomimetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; OBI: Research Funding; Immunogen: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding. Carraway: AbbVie: Other: Independent review committee; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Other: Independent review committee; Astex: Other: Independent review committee; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene, a Bristol Myers Squibb company: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Maciejewski: Novartis: Consultancy; Regeneron: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Alexion: Consultancy.

Allogeneic Hematopoietic Cell Transplantation for Acute Myeloid Leukemia with Hyperdiploid Complex Karyotype: A Study from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Introduction: Cytogenetics remains one of the most important prognostic factors in acute myeloid leukemia (AML) patients, even for outcomes after allogeneic hematopoietic cell transplantation (allo-HCT). Complex karyotype (CK) constitutes a cytogenetic category with a very adverse prognosis in this setting. However, CK is a heterogenous and loosely defined category which comprises a high diversity of cytogenetic subtypes, which is highly enriched with specific cytogenetic subtypes characterized by losses of chromosomal material at critical regions known to confer a poor prognosis per se, such as monosomal karyotype, del(7q)/-7, del(5q)/-5 or abnormalities leading to 17p region loss. On the contrary, rare AML cases characterized with only multiple numerical abnormalities known as pure hyperdiploid karyotype (HDK), have a controversial prognosis. We hypothesized that pure complex HDK AML has a distinct and much better prognosis after allo-HCT compared to non-HDK, CK AML. Methods: We selected from the EBMT registry adult patients with AML and a full cytogenetic report. HDK was defined by the presence of 49 chromosomes or more. Patients were then stratified by pure HDK (pHDK) and HDK with other cytogenetic abnormalities (HDK+), characterized by HDK and the presence of a prognostic-defining cytogenetic abnormality such as del(5q)/-5, del(7q)/-7, del(17p)/-17/i(17q), inv(3q21-26)/t(3;3)(q21;q26) or t(9;22). We included only first allo-HCT from a sibling or unrelated donor (UD) performed between 2000 and 2018. Results: A total of 236 patients were identified as having HDK. There were 95 pHDK and 141 HDK+. Median age at transplantation was 53 years (range, 18-74) and median follow-up was 43 months (range, 35-56). A diagnosis of secondary AML was reported in 48 patients (20%). At the time of allo-HCT, 180 patients (76%) were in first remission (CR1), and 56 were beyond CR1 (24%). Eighty-five (39%) patients received an allo-HCT from a sibling donor, with more matched unrelated donors (MUD) in HDK+ patients (p=0.02). Most patients (70%) had a Karnofsky performance status (KPS) score of more than 90% at the time of transplantation. A myeloablative conditioning regimen was administered in 46% of the patients. In vivo T-cell depletion was part of the regimen in 66% of the patients. The most frequent trisomies were trisomy 8, 21, 13, and 22. The 2-year probability of non-relapse mortality (NRM) was 26% for the entire cohort. The 2-year probability of LFS was 50% for pHDK and 31% for HDK+ (p=0.003). The 2-year probability of overall survival (OS) was 57% for pHDK and 36% for HDK+ (p=0.007). The 2-year cumulative incidence of relapse (RI) was 22% for pHDK and 44% for HDK+ (p=0.001) (Figure 1). The cumulative incidence of grade II-IV acute graft-versus-host disease (GvHD) and chronic GvHD was 34% and 33%, respectively, for the entire cohort. Finally, the 2-year probability of GvHD and relapse-free survival (GRFS) was 36% for pHDK and 21% for HDK+ (p=0.01). On multivariate analysis, pHDK remained associated with significantly better LFS, OS and GRFS and higher RI (all p-values<0.004). Age was associated with lower OS (p=0.05). Being in remission at the time of allo-HCT was associated with better LFS, OS and GRFS, and lower NRM and RI (all p-values<0.02). Secondary AML, donor type, KPS, and conditioning regimen intensity were not associated with any outcome in multivariate analysis. Conclusions: AML with pHDK has a better outcome after allo-HCT in terms of RI, LFS, OS and GRFS. pHDK AML constitutes probably a distinct cytogenetic entity from HDK+ or other non-hyperdiploid CK AML. CK remains a strong indication for allo-HCT, but the type of abnormalities included in CK significantly influences the outcome and should guide how to manage patients after allo-HCT in terms of immunosuppression withdrawal or prophylactic/preemptive post-transplant interventions such as use of hypomethylating agents or donor lymphocyte infusions. Figure 1 Figure 1. Disclosures Labopin: Jazz Pharmaceuticals: Honoraria. Ganser: Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria; Celgene: Honoraria. Socie: Alexion: Research Funding. Forcade: Novartis: Other: travel grant. Chalandon: Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Gilead, Amgen, Jazz, Astra Zenec: Other: Travel EXpenses, Accomodation; Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Amgen: Other: Advisory Board; Incyte: Speakers Bureau. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Kröger: Novartis: Research Funding; Riemser: Honoraria, Research Funding; Sanofi: Honoraria; Neovii: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Gilead/Kite: Honoraria; Celgene: Honoraria, Research Funding; AOP Pharma: Honoraria. Esteve: Jazz: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Abbvie: Consultancy; Novartis: Consultancy, Research Funding; Astellas: Consultancy; Pfizer: Consultancy; Novartis: Research Funding. Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria.

Differential Prognostic Relevance of Measurable Residual Disease in Acute Myeloid Leukemia Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation in First Versus Second Morphologic Remission

Introduction: Allogeneic stem cell transplantation (HSCT) offers still the best chance for relapse-free long-term survival for most patients (pts) with acute myeloid leukemia (AML). Allogeneic HSCT may be performed as first line consolidation or following first relapse. Evaluation of measurable residual disease (MRD) at the time of HSCT allows for risk stratification apart from genetic risk at diagnosis. Outcomes of pts transplanted in first vs. second complete remission (CR) or CR with incomplete recovery (CRi) have not been assessed in the context of MRD status at HSCT. Methods: We analyzed 580 AML pts consolidated by allogeneic peripheral blood HSCT at a median age of 60 (range 16-77) years in either first (79%) or second (21%) complete remission (CR) or CR with incomplete peripheral recovery (CRi). Conditioning regimens were non-myeloablative (66%), reduced-intensity (6%) or myeloablative (28%) according to EBMT guidelines. At diagnosis, cytogenetics, and the mutation status of CEBPA, NPM1 and presence of FLT3-ITD were assessed. Using a next-generation targeted amplicon sequencing approach we analyzed a panel comprising 54 recurrently mutated genes in myeloid malignancies on the MiSeq platform (Illumina). In pts with adequate material available (n=300), MRD status at HSCT based on NPM1 mutations , BAALC, MN1, and WT1 expression were evaluated and interpreted as published previously (Lange 2010, Jentzsch 2017 & 2019, Bill 2018). MRD pos pts were defined by being positive for any of the analyzed markers. Median follow up after HSCT was 3.9years. Results: Compared to pts transplanted in first CR/CRi, pts in second CR/CRi were less likely to have a secondary AML (P=.002). They less frequently had a monosomal (P<.002) or complex (P<.001) karyotype, but were more likely to have a normal karyotype (P<.001), to be NPM1 mutated (P=.001), to be biallelic CEBPA mutated by trend (P=.09), and to harbor a FLT3-ITD (P=.04). Pts in second CR/CRi received significantly less chemotherapy prior to HSCT (relapse to HSCT, 71%, 26%, and 3% of pts received 1, 2, or 3 or more cycles, respectively) than pts in first CR/CRi (diagnosis to HSCT, 16%, 61%, and 23% of pts received 1, 2, or 3 or more cycles, respectively, P<.001). Pts transplanted in second CR/CRi tended to more often be MRD pos (P=.10) and had a significantly higher cumulative incidence of relapse (CIR, P<.001, Figure 1A) and significantly shorter event-free survival (EFS, P=.002, Figure 1B) than pts transplanted in first CR/CRi. The MRD status at HSCT was an important prognostic factor in both pts transplanted in first (CIR, P<.001 and EFS, P=.002) and second CR/CRi (CIR, P<.001 and EFS, P=.04, Figure 1C,D). Similar results were obtained when we analyzed the four MRD markers separately. Noteworthy, MRD pos pts transplanted in first CR/CRi and MRD neg pts transplanted in second CR/CRi had similar CIR (P=.42) and EFS (P=.70), which again reflects the worse outcomes of AML pts transplanted in second compared to first CR/CRi as well as the prognostic significance of MRD assessment irrespective of the adapted markers. In the clinically highly relevant group of ELN intermediate risk AML pts where the optimal consolidation (chemotherapy vs. allogeneic HSCT) remains a matter of debate, both MRD neg pts transplanted in in first or second CR/CRi had favorable outcomes (at three years, CIR 15% and 13%, respectively, and EFS, 64% and 63%, respectively), while outcomes were intermediate in MRD pos pts transplanted in first CR/CRi (at 3 years, CIR 38%, and EFS 46%) and very dismal in MRD pos pts transplanted in second CR/CRi (at 3 years, CIR 86%, and EFS 14%). Conclusion: Despite pts transplanted in second CR/CRi had better disease risk at diagnosis, including a lower incidence of monosomal or complex karyotypes, secondary AML and a higher incidence of NPM1 mutations, they had a higher CIR and shorter OS than pts transplanted in first CR/CRi. While the MRD status at HSCT remained an important risk factor independently of the number of remission, MRD pos pts transplanted in first CR/CRi had comparable outcomes as MRD neg pts transplanted in second CR/CRi. The adverse outcomes of MRD pos patients and pts transplanted in second CR/CRi should be taken into account when planning consolidation treatment in AML pts. Benefit of additional therapies prior to HSCT should be evaluated to improve outcomes of eligible MRD pos AML pts, especially when transplanted in second CR/CRi. Figure 1 Figure 1. Disclosures Jentzsch: Astellas: Honoraria; Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Backhaus: Bayer: Other: Current Employment of Family Member. Franke: Novartis: Honoraria; MSD: Honoraria; Jazz Pharmaceuticals: Honoraria, Other: Travel Sponsoring; Gilead: Honoraria, Other: Travel Sponsoring; BMS: Honoraria; Pfizer: Honoraria. Vucinic: Novartis: Honoraria; Janssen: Honoraria, Other: Travel Sponsoring; Abbvie: Honoraria, Other: Travel Sponsoring; Gilead: Honoraria, Other: Travel Sponsoring; MSD: Honoraria. Platzbecker: Geron: Honoraria; Novartis: Honoraria; Takeda: Honoraria; AbbVie: Honoraria; Janssen: Honoraria; Celgene/BMS: Honoraria. Schwind: Novartis: Honoraria, Research Funding; Pfizer: Honoraria.

TP53 mutation in newly diagnosed acute myeloid leukemia and myelodysplastic syndrome

Objectives TP53 mutation is found frequently in therapy related acute myeloid leukemia (AML)/ myelodysplastic syndrome (MDS), AML and MDS patients with monosomy or complex karyotype. However, the prevalence and treatment outcome in TP53 mutated AML/MDS patients in Asian population are scarce. We therefore conducted this study to analyze the prevalence and the treatment outcomes of TP53 mutation in AML and MDS-EB patients. Methods Patients with newly diagnosed AML and MDS-EB were recruited, extraction of deoxyribonucleic acid from bone marrow samples were done and then performing TP53 mutation analysis, using MassArray® System (Agena Bioscience, CA, USA). Results A total of 132 AML/MDS patients were recruited, patients with de novo AML, secondary AML, MDS-EB1, MDS-EB2 and T-AML/MDS were seen in 66, 13, 9, 9 and 3%, respectively. TP53 mutation was found in 14 patients (10.6%), and prevalence of TP53 mutation in T-AML/MDS, secondary AML, de novo AML and MDS-EB patients were 50, 17.6, 9.2 and 8%, respectively. Three patients had double heterozygous TP53 mutation. Mutated TP53 was significantly detected in patients with monosomy and complex chromosome. Common TP53 mutation were R290C, T220C, A249S and V31I which V31I mutation was reported only in Taiwanese patients. Most variant allele frequency (VAF) of TP53 mutation in the study were greater than 40%. Three year-overall survival (OS) in the whole population was 22%, 3y-OS in AML and MDS-EB patients were 22 and 27%, respectively. The 1y-OS in patients with TP53-mutant AML/MDS were shorter than that in TP53 wild-type patients, 14% versus 50%, P = 0.001. In multivariate analysis, factors affecting OS in 132 AML/MDS patients was mutant TP53 (P = 0.023, HR = 1.20–7.02), whereas, WBC count> 100,000/μL (P = 0.004, HR = 1.32–4.16) and complex karyotype (P = 0.038, HR = 1.07–9.78) were associated with shorter OS in AML patients. Discussion In this study, the prevalence of TP53 mutation in de novo AML and MDS-EB patients were low but it had impact on survival. Patients with monosomy or complex karyotype had more frequent TP53 mutation.

tinguishing AML from MDS: A fixed blast percentage may no longer be optimal

Patients with acute myeloid leukemia (AML) have conventionally received more "intense" therapy than patients with myelodysplastic syndromes (MDS). Although less intense therapies are being used more often in AML, the AML-MDS dichotomy remains, with the presence of ≥ 20% myeloblasts in marrow or peripheral blood generally regarded as defining AML. Consequently, patients with 19% blasts are typically ineligible for AML studies, with patients with 21% blasts ineligible for MDS studies. Here we cite biologic and clinical data to question this practice. Biologically, abnormalities in chromosome 3q26,and mutations in NPM1, and FLT3, regarded as AML-associated, also occur in MDS. The genetic signatures of MDS, particularly cases with 10-19% blasts (MDS-EB2), resemble those of AML following a preceding MDS ("secondary AML"). Mutationally, secondary AML appears at least as similar to MDS-EB2 as to de novo AML. Patients presenting with de novo AML but with secondary-type AML mutations, appear to have the same poor prognoses associated with clinically defined secondary AML. Seattle data indicate that after accounting for European LeukemiaNet (ELN) 2017 risk, age, performance status, clinically secondary AML, and treatment including allogeneic transplant, patients with WHO-defined AML (n=769) have similar rates of OS, EFS and CR/CRi as patients with MDS-EB2 (n=202). We suggest defining patients with 10-30% blasts ("AML/MDS") as eligible for either AML or MDS studies. This would permit empirical testing of the independent effect of blast percentage on outcome, allow patients access to more therapies, and potentially simplify the regulatory approval process.

Characteristics and outcomes of patients diagnosed with DNMT3A mutated acute myeloblastic leukemia.

e19018 Background: Advances in molecular profiling have identified recurring gene mutations in acute myeloid leukemia (AML) that have independent prognostic significance with several being targets for the development of new small molecule inhibitors. DNMT3A mutations have been reported in up to 34% of patients with AML. Mutations of this gene are associated with silencing of tumor suppressor genes, thereby leading to leukemogenesis. Several prior reports have suggested an association with worse outcomes. Methods: We retrospectively reviewed records of 258 patients with ND AML with DNMT3A mutations who presented to our institution from 2002 to 2020. We analyzed their clinical and laboratory characteristics. We estimated their overall survival (OS) and disease-free survival (DFS) through the Kaplan-Meier method. P-value was 2-tailed, ≤ 0.05 was considered statistically significant with a confidence interval of 95%. Univariate and multivariate analyses were also applied. Results: Our cohort had a median age of 66 years, 56% were female. The majority of the patients (77%) had de novo AML and the M0 FAB subtype was predominantly observed in 70%. Diploid karyotype was detected in 60% while complex karyotype in 14% of patients. DNMT3A was most frequently mutated at codon 882 (64%). NPM1 was the most frequent concomitant mutation followed by FLT3-ITD and IDH2. Age > 65 years (p = 0.001) and presence of concomitant TP53 mutation (p < 0.001) were associated with worse survival and concomitant NPM1 was associated with a 40% reduction of death, p = 0.003. Secondary AML and concurrent TP53 mutation were associated with a higher risk of relapse, (p < 0.001 for both). Intensive chemotherapy (ICT) was administered to 82 patients of which 68 achieved a complete response or CR with incomplete count recovery (CRi). Nineteen patients were treated with Cladribine plus low dose Ara-C (Clad-LDAC) and CR or CRi was achieved in 16 patients. Eleven treated with Clad-LDAC-Ven and all achieved CR/CRi. Hypomethylating agents (HMA) were given to 22 patients of which 10 achieved CR/CRi. Twenty-five received HMA-Ven, of these, CR/CRi was achieved in 20 patients (p = 0.02). There was an 80% and 90% reduction of death with ICT, p < 0.001 and Clad-LDAC-Ven, p = 0.04 respectively. Moreover, the risk for relapse was reduced by 70% and 90% with ICT and Clad-LDAC-Ven respectively. Ninety-seven patients were treated with immunotherapy, FLT3 inhibitors, and IDH inhibitors, which were not included in this analysis. Conclusions: DNMT3A mutations have an independent prognostic impact in patients diagnosed with AML. Among these patients, older age, secondary AML, a concomitant mutation in TP53 showed a significant negative impact in terms of OS and DFS. Concomitant mutations in NPM1 and IDH2 were associated with better outcomes. Treatment with intensive chemotherapy or clad-LDAC-Ven was associated with the highest response rates.