Arber, Daniel A.

SummaryAmong 210 patients with myelodysplastic syndromes (MDSs) with del(5q), molecular information was available at diagnosis or at least 3 months before leukaemic transformation in 146 cases. Multivariate analysis identified therapy‐related setting (p = 0.02; HR 2.3) and TP53 variant allele frequency (VAF) ≥22% (p < 0.01; HR 2.8), but not SF3B1 mutation (p = 0.65), as independent risk factors for survival. Median survival was 11.7 versus 4 years (5/10‐year survival 73%/52% vs. 42%/14%) in the absence (N = 112) versus presence (N = 34) of ≥1 risk factors; leukaemia‐free survival was affected by TP53 VAF ≥22% (p < 0.01). Such information might inform treatment decision‐making in MDS‐del(5q) regarding allogeneic stem cell transplant.

Introduction: ECOG ACRIN E1910 is a randomized phase III trial that showed that adults with newly diagnosed BCR::ABL1 negative acute lymphoblastic leukemia (ALL) who become MRD negative (&lt;0.01%) after induction chemo who receive blinatumomab with conventional chemotherapy (chemo) have improved survival compared with those who received chemo only (Litzow et al, Blood (2022) 140: Supplement 2, LBA-1). However, not all pts were able to receive all four planned cycles of blinatumomab in consolidation. In this report we assessed outcomes of pts in the blinatumomab arm of the trial who received all 4 cycles of blinatumomab compared to those who received 1-2 cycles. Methods: Patient between the ages of 30 and 70 with newly diagnosed BCR::ABL1 negative B-lineage ALL were enrolled and initially received 2.5 months of combination induction chemo utilizing a BFM-like regimen adapted from the E2993/UKALLXII clinical trial, with pegaspargase (after induction only for patients &gt;=55 years of age) and addition of rituximab for CD20 positive patients. After remission induction (step 1) pts in morphologic complete remission (CR/CRi) received an intensification course of high dose methotrexate with pegaspargase for CNS prophylaxis (step 2). At the conclusion of step 2, remission and MRD status were determined centrally by 6-color flow cytometry with MRD negativity defined as &lt;0.01%. In the primary analysis subset, MRD negative patients were randomized to receive an additional 4cycles of consolidation chemo or 2 cycles of blinatumomab at 28 mcg/day (flat dose) for 28 days each cycle followed by 3 cycles of consolidation chemo, another 4-week cycle of blinatumomab (3rd cycle of blinatumomab) followed by an additional cycle of chemo and then a 4th cycle of blinatumomab (step 3). Following completion of consolidation chemo +/- blinatumomab, pts were given 2.5 years of POMP maintenance therapy timed from the start of the intensification cycle (step 4). Estimates of OS were calculated using the Kaplan-Meier method. Comparison of OS between treatment arms were conducted using the stratified log-rank test and Cox proportional-hazards model with age, CD20 status, rituximab use, and whether pts intend to receive HSCT or not as stratification factors. As the number of cycles needed to optimize outcome has not been studied, an unplanned landmark analysis was used to compare OS of pts in the blinatumomab arm who received all 4 cycles o those who received 1-2 cycles. Time 0 was chosen as 9 months post step 3 randomization (the time that patients were supposed to complete 4 cycles of blina). Four pts who received blinatumomab but died within 9 months post step 3 randomization were therefore excluded from this analysis. Results: The study was activated on December 17, 2013 and closed to enrollment on October 15, 2019. 772 pts were screened for the trial and 488 were enrolled on step 1 induction therapy. The median age of the pts was 51 years (range 30-70). 224 MRD negative pts were randomized, 112 pts to each arm. In the blinatumomab arm 12 pts received 1 cycle (11%), 32 pts received 2 cycles (29%), 4 pts received 3 cycles (4%) and 63 pts received 4 cycles (57%). The OS of pts who received 1-2 cycles of blinatumomab was compared to control (Figure 1) The difference was not significant (hazard ratio 0.62, 95% CI 0.28 to 1.34, p=0.22). Fig 2 compares the survival of those who received 1-2 cycles to those who received 4 cycles ( (HR: 0.39, 95% CI 0.12 to 1.16, p=0.076). Conclusion: The addition of blinatumomab to consolidation chemotherapy resulted in a significantly better overall survival compared to chemotherapy alone in pts with newly diagnosed B-lineage ALL who were MRD negative after intensification. This represents a new standard of care for pts aged 30-70 years with BCR::ABL1 negative ALL. The optimal dose and number of cycles is however unknown. In this unplanned subgroup analysis we demonstrate that a survival benefit can only be confirmed in patients who receive the intended 4 cycles of blinatumomab during consolidation. Further studies will be needed to determine if fewer cycles can provide a similar benefit.

Background: According to the international consensus classification (ICC), diagnosis of myelodysplastic syndromes (MDS) with del(5q) requires presence of i) del5q, alone or associated with no more than one other cytogenetic abnormality, exclusive of -7/del(7q), ii) &lt;5% bone marrow (BM) and &lt;2% circulating blasts, and iii) the absence of “multi-hit” TP53 ( Arber et al. Blood 2022;140: 1200). We have recently reported on TP53 variant allele frequency (VAF) ≥22% being the sole genetic predictor of inferior survival in MDS-del(5q) (Fleti. et al. AJH 2023;98:E76). In the current study, we examined the additional prognostic impact of therapy-related setting, in the context of TP53 VAF and other risk factors. Methods : The current study included patients with MDS-del(5q) who were seen at the Mayo Clinic or Moffitt Cancer Center, USA. Diagnosis of MDS-del(5q) and therapy-related qualification was according to ICC criteria ( Arber et al. Blood 2022;140: 1200), with the exception that patients with biallelic or multi-hit TP53 were included to allow unbiased analysis of impact on prognosis. Patient selection was based on availability of mutation information from next-generation sequencing (NGS). The latter was assessed either at diagnosis or at different time points during the disease course, but at least 3 months before leukemic transformation. Otherwise, all analyses, including estimation of overall and leukemia-free survival, were based on variables collected at time of initial diagnosis of MDS-del(5q). TP53 mutation VAF threshold of 22% was considered based on our previously published report cited above. Age cutoff at 67 years was determined by ROC analysis. Conventional statistical methods were applied using JMP Pro 16.0.0 software (SAS Institute, Cary, NC, USA). Results: A total of 210 patients (median age 72 years; 65% females), meeting the above-stipulated criteria for MDS-del(5q), were considered: 172 primary and 38 therapy-related. Table 1 outlines clinical and laboratory characteristics obtained at the time of diagnosis: 42% were transfusion-dependent, 69% had hemoglobin level &lt;10 g/dL, 30% platelet count &lt;150 x 10(9)/L, and 15% carried additional cytogenetic abnormality. NGS data performed either at diagnosis or at least 3 months prior to leukemic transformation was available in 146 patients; the most frequent mutations were TP53 (21%), SF3B1 (16%), DNMT3A (12%), TET2 (12%), ASXL1 (10%), and JAK2 (7%) (Table 1). At a median follow-up of 3.9 years (range 0.002-18.5) for living patients, 95 (45%) deaths and 34 (16%) leukemic transformations were recorded; treatment undertaken included lenalidomide in 162 (77%) cases. NGS data-exclusive multivariable analysis that included all 210 patients identified therapy-related setting (p&lt;0.01; HR 2.9; Figure 1a), age &gt;67 years (p=0.01; HR 1.8), transfusion-dependency (p=0.04; HR 1.5), and platelet count &lt;150 x 10(9)/L (p=0.03; HR 1.6), as independent predictors of inferior survival. The significant effect of age and platelet count was sustained when analysis was limited to patients with primary MDS-del(5q) but lost when applied to therapy-related disease. NGS data-inclusive multivariable analysis, which was applicable to the subset of 146 patients, identified, as risk factors, therapy-related setting (p&lt;0.01; HR 2.3) and TP53 VAF ≥22% (p&lt;0.01; HR 2.4; Figure 1b) while age &gt;67 years sustained borderline significance (p=0.07; HR 1.8). Figure 1c depicts survival data based on the presence or absence of TP53 VAF ≥22% and therapy-related qualification; low-risk with no risk factors (N=112; median survival 11.7 years; 5/10-year survival 73%/52%) and high-risk with one or both risk factors (N=34; median survival 4 years; 5/10-year survival 42%/14%); leukemia-free survival was affected by TP53 VAF ≥22% (p&lt;0.01) but not therapy-related setting (p=0.13). Conclusions : The current study highlights TP53 VAF and therapy-related setting as the most prominent risk factors for survival in MDS-del(5q) and proposes a simple risk model that distinguishes patients with a projected 10-year survival that exceeds 50%, in the absence of both risk factors, and plummets to 14%, in the presence of one of the two risk factors. Accordingly, allogeneic stem cell transplant might be deferred in the former instance while it should be pursued sooner than later, in the latter instance.

Background: Biallelic TP53 alterations result from either sequence variations or deletions involving TP53 and are not necessarily synonymous with “multi-hit TP53”. According to the 2022 international consensus classification (ICC) for myeloid neoplasms (MN), multi-hit TP53 signifies i) the presence of two or more distinct TP53 mutations, each with variant allele frequency (VAF) ≥10%, ii) a single TP53 mutation with VAF ≥50%, or iii) a single TP53 mutation with VAF ≥10% accompanied by a cytogenetically-apparent del(17p13.1), copy-neutral loss of heterozygosity (LOH) at the 17p TP53 locus, or, in the absence of LOH information, complex karyotype ( Arber et al. Blood 2022;140: 1200). The current study is focused on MN with multi-hit TP53 and examines the additional prognostic impact of morphologic subtype designation, bone marrow (BM) or peripheral blood (PB) blast percentage, TP53 VAF, and MN with diagnostic qualifiers (i.e., therapy-related, or secondary progressing from myelodysplastic/myeloproliferative/overlap syndromes/neoplasms). Methods : The current study was conducted under an institutional review board approved minimum risk protocol that allowed retrospective collection and analysis of data from Mayo Clinic patient records. Multi-hit TP53 was defined as per ICC criteria as outlined above ( Arber et al. Blood 2022;140: 1200). Morphologic subtype designations of MN were according to ICC criteria and assigned at the time of TP53 detection. NGS and cytogenetic information was available in all study patients. Survival analyses were calculated from time of TP53 mutation detection. Conventional statistical methods were applied using JMP Pro 16.0.0 software (SAS Institute, Cary, NC, USA). Results : Initial screening flagged 143 patients with biallelic TP53 abnormalities derived from formal laboratory reports of NGS data and cytogenetic studies; of these, 130 met ICC criteria for multi-hit TP53: pure erythroid leukemia (PEL; N=24), acute myeloid leukemia (AML)-not PEL (N=54), myelodysplastic syndromes (MDS; N=36), MDS/AML (N=11), and other MN (N=5). Of these 130 informative cases, 128 (98%) harbored complex/monosomal karyotype (CK/MK). Further analysis excluded patients with “other” MN (N=5) and those without CK/MK (N=2), the latter to mitigate the confounding effect of CK/MK on survival and the former because of small sample size and disease heterogeneity. Clinical and laboratory characteristics of the 124 study patients are outlined in table 1. Survival analysis stratified by ICC-defined MN subtypes revealed the prognostic relevance of morphological distinction between PEL vs “AML-not PEL” (p&lt;0.01; HR 2.4) and PEL vs “ TP53-muated MDS/AML” (p=0.02; HR 2.3) while survival was similar between “AML-not PEL” and “ TP53-mutated MDS/AML” (p=0.9; Figure 1a). Survival in “ TP53-mutated MDS” was significantly longer, compared to PEL (p&lt;0.01; HR 0.2), “ TP53-mutated AML-not PEL” (p=0.01; HR 0.5), and “ TP53-mutated MDS/AML” (p=0.07; HR 0.5), the latter with borderline significance (Figure 1a). Multivariable analysis confirmed the independent prognostic relevance of ICC subtype designation (p&lt;0.01) and also revealed additional negative prognostic contribution from advanced age (p=0.02), male gender (p=0.02), MN, secondary (p&lt;0.01), MN, therapy-related (p=0.03), and DNMT3A mutation (p=0.02). Significance was retained in all instances, with the exception of MN, therapy-related (p=0.15), when analysis was repeated after excluding PEL cases (Figure 1b). Conclusions : The current study confirms the prognostic validity of the ICC morphologic subtype designation and TP53 VAF classification threshold, in the context of multi-hit TP53. The study also highlights the prognostic distinction between PEL and “ TP53-mutated AML-not PEL” and the prognostic alignment between the latter and “ TP53-muated MDS/AML”, both of which displayed inferior survival, compared to “ TP53-mutated MDS”. The study also suggests additional prognostic contribution from secondary and therapy-related qualification while the observation regarding DNMT3A mutation requires validation with higher number of informative cases.

BACKGROUND: Recently proposed World Health Organization (WHO, 5 th edition) and International Consensus Classification (ICC) recognized myeloid neoplasms (MN) harboring TP53-mutated ( TP53mut) as a separate entity. However, there are critical differences between the two classifications regarding allelic-status, variance allele frequency (VAF) cut-off and blast categories, that may lead to under- or overestimation of the risk. METHODS: We analyzed MN harboring TP53mut (VAF ≥2%, n=536) managed at Mayo Clinic (USA) and South Australia Health Network (Australia). ICC (Arber et al, Blood 2022) and WHO (Bluebook, Beta v2) definitions were used to stratify MN harboring TP53mut. RESULTS: Of 536 cases, 379 (71%) had myelodysplastic syndromes (MDS) (&lt;20% blasts) and 157 (29%) had acute myeloid leukemia (AML). Using WHO, 160 (42%) of 379 were classified as MDS-bi TP53 as they harbored 2 TP53mut (n=115; 30%) or 1 TP53mut plus confirmed loss of heterozygosity (LOH) or copy neutral LOH (cnLOH) of TP53 locus (n=45; 12%). Sixty-two (16%) TP53mut MDS with VAF &gt;49% were classified as presumptive MDS-bi TP53. Of the 157 cases with 1 TP53mut VAF ≤49%, 17 confirmed to have an intact wild-type TP53 copy and were classified as monoallelic. While 140 (89%) cases did not have copy number variation (CNV) analysis. We next evaluated the number of TP53mut cases classified differently by WHO and ICC. As WHO does not recognize TP53mut AML as a separate entity, 157 (29%) TP53mut AML were not classifiable. 46% (174/379) of the TP53mut MDS including 48 (30%), 12 (19%) and 79 (65%) of bi TP53, presumptive bi TP53 and monoallelic TP53mut MDS according to WHO were classified differently by ICC ( Figure 1A). Discordance between the two classifications were predominantly driven by: (i) The difference in VAF cut-off. Sixty patients (11%) with TP53mut VAF &lt;10% were excluded from the ICC classification of TP53mut MN as it mandates TP53mut VAF cut-off ≥10%. 11 (18%) and 41 (68%) of these had bi TP53, monoallelic TP53mut MDS by WHO criteria while 8 (13%) had AML. Importantly, within the VAF &lt;10% cohort, median overall survival (OS) of 2 TP53mut or 1 TP53mut with 17p13.1 (hereafter 17p) deletion or complex karyotype (CK, n=30) was significantly poor compared to 1 TP53mut VAF &lt;10% (11.6 vs 32.4 months; P =0.002, Figure 1B), suggesting that ICC may underestimate the poor prognosis of multi-hit or multi-hit equivalent TP53mut MN with VAF &lt;10%. (ii) The difference in bone marrow blast cut-off. The underlying assumption by WHO is that prognosis of bi TP53mut MDS is poor irrespective of blast percentage category (0-9% vs 10-19%). In contrast, ICC considers that TP53mut MDS/AML (blasts 10-19%) is associated with poor prognosis irrespective of TP53 allelic status. Median OS of TP53mut MDS with 10-19% blasts was significantly poor compared to blast 0-9% (6.4 vs 11.6 months, P &lt;0.0001). Second, median OS of bi TP53mut was significantly poor than monoallelic TP53mut in MDS- blast 0-9% (10.1 vs 15.9 months; P =0.0001) but not in blasts 10-19% (6.8 vs 6.2 months; P =0.19). Hence, exclusion of monoallelic TP53mut MDS with blast 10-19% as TP53mut MN from the WHO classification may underestimate the poor prognosis. (iii) The difference in the definition of biallelic and multi-hit TP53 loss. 35 cases with 1 TP53mut VAF ≤49%, had 17p deletion but did not have CNV analysis to confirm the loss of TP53 locus and could not be classified further using WHO. ICC classified 18 (50%) of these cases as multi-hit. Median OS of 1 TP53mut VAF ≤49%, and 17p deletion on karyotype was significantly poor than 1 TP53mut (VAF ≤49%without 17p deletion on karyotype (6.4 vs 14.6 months, P =0.001). (iv) The difference in the definition of multi-hit equivalent. 32% (33/104) WHO defined monoallelic cases without available CNV data, were classified as multi-hit-equivalent by ICC as they harbored CK. However, WHO does not consider CK as presumptive evidence of bi TP53. Median OS of 1 TP53mut VAF ≤49% with CK was significantly poor compared to 1 TP53mut without CK (8.2 vs 26.9 months, P =0.0008). CONCLUSION: Our study provides evidence that poor prognosis of ‘multi-hit’ TP53 with VAF &lt;10% is underestimated by ICC. On the other hand, poor prognosis of monoallelic TP53 MDS with 10-19% blasts as well as 1 TP53mut VAF ≤49% in the presence of CK is underestimated by WHO. These data suggest that both classifications can be further refined.

AbstractBased on new data and increased understanding of disease molecular genetics, the international consensus classification (ICC) has made several changes in the diagnosis and classification of eosinophilic disorders and systemic mastocytosis. Myeloid/lymphoid neoplasms with eosinophilia (M/LN‐eo) and gene rearrangements have been renamed as M/LN‐eo with tyrosine kinase gene fusions (M/LN‐eo‐TK). The category has been expanded to include ETV6::ABL1 and FLT3 fusions, and to accept PCM1::JAK2 and its genetic variants as formal members. The overlaps and differences between M/LN‐eo‐TK and BCR::ABL1‐like B‐lymphoblastic leukemia (ALL)/de novo T‐ALL sharing the same genetic lesions are addressed. Besides genetics, ICC for the first time has introduced bone marrow morphologic criteria in distinguishing idiopathic hypereosinophilia/hypereosinophilic syndrome from chronic eosinophilic leukemia, not otherwise specified. The major diagnostic criteria for systemic mastocytosis (SM) in the ICC remain largely based on morphology, but several minor modifications/refinements have been made in criteria related to diagnosis, subclassification, and assessment of disease burden (B‐ and C‐findings). This review is to focus on the ICC updates related to these disease entities, illustrated through changes related to morphology, molecular genetics, clinical features, prognosis, and treatment. Two practical algorithms are provided in navigating through the diagnosis and classification systems of hypereosinophilia and SM.

AbstractA group of international experts, including hematopathologists, oncologists, and geneticists were recently summoned (September 2021, Chicago, IL, USA) to update the 2016/17 World Health Organization classification system for hematopoietic tumors. After careful deliberation, the group introduced the new International Consensus Classification (ICC) for Myeloid Neoplasms and Acute Leukemias. This current in‐depth review focuses on the ICC‐2022 category of JAK2 mutation‐prevalent myeloproliferative neoplasms (MPNs): essential thrombocythemia, polycythemia vera, primary myelofibrosis, and MPN, unclassifiable. The ICC MPN subcommittee chose to preserve the primary role of bone marrow morphology in disease classification and diagnostics, while also acknowledging the complementary role of genetic markers for establishing clonality, facilitating MPN subtype designation, and disease prognostication.