Atanasio, Alessandro

Background: The JAK2 46/1, also referred to as the GGCC, haplotype, is represented by 4 main SNPs spanning a region of 250kb in chr9 including the JAK2 gene, that are in complete linkage disequilibrium. The GGCC haplo was found to confer susceptibility to JAK2 mutated myeloproliferative neoplasms (MPN) (Jones AV, 2009; Olcaydu D, 2009; Kilpivaara O, 2009) while association with JAK2-wildtype MPN remains controversial (Pardanani A, 2010; Jones AV, 2010; Guglielmelli P, 2010; Trifa A, 2016). The GGCC haplo was also found enriched in MPN pts with splancnic vein thrombosis (SVT) (Smalberg JH, 2011), and to correlate with higher JAK2V617F variant allele frequency (VAF) (Alvarez-Larran, A, 2012). Nullizigosity for GGCC haplo was associated with reduced survival (OS) in pts with myelofibrosis (MF) (Tefferi A, 2019), but no information on the impact of GGCC haplo status with phenotype and outcome in PV is available. Aim: To assess the clinical correlates and the prognostic significance of GGCC haplo status in a large cohort of pts with PV. Pts and Methods: A total of 399 PV pts, all JAK2V617F mutated, diagnosis revised according to 2022 ICC criteria, were genotyped for 46/1 haplotype by PCR allele discrimination with rs12343867 (with the “C” allele standing for 46/1 haplotype). Results: A total of 301 pts (75.4%) had the C allele, of which 143 (47.5%) were CC homo and 158 (52.5%) CT hetero; 98 (24.6%) were nullizygous for GGCC (TT). Since preliminary analysis disclosed no significant difference between CT and TT haplotype for all variables considered, homozygous CC pts were compared to TT+CT. The CC haplotype was associated with higher leukocytes (median 11.3x10e9/L vs 9.6, p<.001), higher hemoglobin (18.4 g/dL vs 17.5, p<.001), lower platelets (441x10e9/L vs 514, p=.002) more aquagenic pruritus (51.8% vs 33.2%, p=.001), and higher JAK2VAF (60.8+-24.8% vs 36.8+-19.7%, p<.001) at diagnosis. Pts with a VAF >50% were 69% in CC versus 24.1% in TT+CT pts (p<.001). ASXL1 mutations were enriched among CC pts (20.3% vs 9.4%, p=0.04), otherwise no difference regarding additional myeloid mutations was noted. All above differences remained significant when considering CC versus TT and CT separately. More pts with CC haplotype suffered from venous thrombosis (VT) during the FU (16.1% vs 4.3%, p<.001), no difference was noted for arterial thrombosis nor for splancnic vein thrombosis. VT-FS by Kaplan Meyer was significantly shorter (p<.001) in CC pts; the rate of VT at 5, 10, 15y after diagnosis, was 5.5%, 12%, 20.2% for CC versus 2.6%, 3.4%, 6.4% for TT+CT, respectively (all p<.001). In multivariable analysis, including JAK2VAF >50%, age >60y, history of VT, WBC >15x10e9/L, only CC haplo remained significant (HR 3.6, 95%CI 1.4-9.5, p=.009). Progression to post-PV MF occurred in 81 pts (20.3%), significantly more among CC (n=45, 31.5%) than TT+CT (n=36; 14.1%; p<.001). Myelofibrosis-FS was significantly shorter in CC vs other genotypes (p=.02). However, in multivariable analysis, only BM fibrosis G1 remained significant (HR 3.2, 1.7-5.9; p<.001). Evolution to blast-phase occurred in 13 pts (3.2%), 9 (6.3%) with CC haplo vs 4 TT+CT (1.6%; p=.01). During the follow-up, 102 pts (25.5%) died, 50 (35%) CC and 52 TT+CT (20.3%; p=.001). In multivariable analysis, including MIPSS-PV variables (Tefferi A 2020), the CC haplo remained significant (HR 1.8, 1.04-3.2, p=.03) together with age (HR 3.0, 1.6-5.7; p<.001), WBC (HR 2.6, 1.3-4.8; p=.004), and thrombosis history (HR 1.9, 1.0-3.7; p=.03). Conclusions. Homozygosity for the 46/1 or CC haplotype contributes to the phenotype diversity of PV, in part possibly mediated by associated higher JAK2V67F VAF, and predicts for incident VT and shorter OS. Supported by AIRC, 21267; MIUR,2022F4WMR3; IHM, PNRR-MAD-2022-12376695

Background In 2013, we published the first International Working Group (IWG) risk model for survival in polycythemia vera (PV), which included 3-tiered age categories, leukocytosis (≥15 x 109/L), and venous thrombosis, as risk variables (Leukemia. 2013;27:1874). In the current study, we examined the individual prognostic contribution from specific leukocyte components and mutations, in order to construct a more contemporary clinical risk model in PV and assess its interaction with genetic risk factors. Methods Study patients were retrospectively recruited from the Mayo Clinic, USA (N=1,007) and the University of Florence, Italy (N=514), in order to serve as discovery and validation cohorts, respectively. Diagnostic criteria were according to the International Consensus Classification (Blood 2022;140:1200). Mutations were screened by next-generation sequencing (NGS). Conventional statistical methods were employed (JMP Pro 17.0.0, SAS Institute, Cary, NC, USA) and optimal cut-points for age, absolute neutrophil (ANC), lymphocyte (ALC), and monocyte (AMC) counts were determined by Receiver Operating Characteristic (ROC) analysis. Akaike Information Criterion (AIC) and ROC plots were used to estimate predictive accuracy. Results Presenting features in the Mayo discovery cohort (N=1,007) included: median age 62.2 years; males 50.7%; median leukocyte count 10.8 x 109/L; leukocyte count ≥15 x 109/L 19%; palpable splenomegaly 32%; pruritus 34%; diabetes 16%; hypertension 61%; arterial thrombosis 14%; and venous thrombosis 14%. ANC, AMC, and ALC information was available in 736 patients with respective median (range) values of 7.6 (1.6-30), 0.6 (0-4.1), and 1.54 (0.19-6.9) x 109/L. At a median follow-up of 8.9 years for the Mayo discovery cohort, 372 (37%) deaths, 46 (4.6%) leukemic transformations, and 200 (20%) fibrotic progressions were recorded. Multivariable analysis (MVA) employing ROC-determined cutoff values revealed adverse survival impact for age >70 years (HR 18.3; p<0.01), age 50-70 years (HR 4.9; p<0.01), AMC ≥0.8 x 109/L (HR 1.5; p<0.01), ANC ≥8 x 109/L (HR 1.5; p<0.01), arterial thrombosis (HR 1.5; p<0.01), diabetes (HR 1.4; p=0.04), and male sex (HR 1.3; p=0.05). A similar MVA applied to the Florence validation cohort (N=514) confirmed significance for age (p<0.01), ANC (p<0.01), AMC (p=0.04), and arterial thrombosis (p<0.01), but not for male sex (p=0.8) or diabetes (p=0.15). Accordingly, age >70 years (4 points), age 50-70 years (2 points), ANC ≥8 x 109/L (1 point), AMC ≥0.8 x 109/L (1 point), and AT (1 point) were included in a revised IWG survival model using the Mayo cohort and validated by the Florence cohort: very low risk (0 points; N=67; median 37 years), low risk (1 point; N=55; median 29.2 years), intermediate risk (2-3 points; N=308; median 20.2 years), high risk (4-5 points; N=217; median 11.5 years), and very high risk (6-7 points; N=88; median 6.3 years). 20-year survival prediction performance of the revised IWG model (AIC 204; AUC 0.88) was superior to that of the 2013 IWG version (AIC 350; AUC 0.86). Mutation information at diagnosis/chronic phase was available in 270 Mayo patients: ASXL1 10%; SRSF2 4%, IDH2 2%, TP53 2%, RUNX1 1.4%. MVA of mutations identified SRSF2 (p<0.01), IDH2 (p=0.01), and ASXL1 (p=0.05), as risk factors for overall survival. The presence of any one adverse mutation was more likely in patients with AMC ≥0.8 x 109/L (24% vs. 7% incidence; p<0.01). In all-inclusive MVA, independent risk factors for OS were age >70 years (HR 14.7), age 50-70 years (HR 6.2), any one adverse mutation (HR 3.4), and ANC ≥8 x 109/L (HR 2.3), but not AMC ≥0.8 x 109/L (p=0.9), arterial thrombosis (p=0.24), or abnormal karyotype (p=0.4). Leukemia-free survival was adversely affected by SRSF2, RUNX1, TP53, and ASXL1 mutations and myelofibrosis-free survival by SRSF2 mutation. Conclusions: The currently proposed revised IWG risk model for survival in PV is globally applicable and based on four easily accessible clinical variables (Age, ANC, AMC, and arterial thrombosis). NGS-derived mutation information overshadows the prognostic relevance of monocytosis, provides additional prognostic information for overall survival, and assists in predicting leukemic and fibrotic transformations.

Abstract Among 281 patients with essential thrombocythemia and calreticulin (CALR) mutation, we found a variant allele frequency of ≥60% to be associated with significantly shortened myelofibrosis-free survival, mostly apparent with CALR type-1 and CALR type-indeterminate mutations.

Background. A mutation in calreticulin ( CALRm) is found in 30-35% of patients (pts) with Essential Thrombocythemia (ET). There are 2 main CALRm mutation types, Type 1/Type 1 like (T1) a 52bp deletion, and Type 2/Type 2 like (T2) a 5bp insertion. Other atypical mutations (T3) occur in a minority of pts. Recent study ( Guglielmelli P et al, BCJ 2023) in pts with myelofibrosis (MF) showed that higher CALR variant allele frequency (VAF) was associated with anemia at diagnosis and during FU, and to features of more advanced disease (CD34 + cell counts, ASXL1 mutation (mut), >2 mutated myeloid genes, and shorter leukocytosis-free survival. Aim. To evaluate whether the CALRm VAF in pts with ET was associated with predefined major clinical outcomes: evolution to MF, transformation to acute leukemia (AML), thrombosis, major bleeding, and survival (OS). Patients and Methods. Diagnosis of ET was strictly according to 2023 WHO and ICC to avoid mis-inclusion of prefibrotic MF. CALRm VAF was determined by capillary gel electrophoresis as the ratio (%) of areas under the curve of CALRm/ CALRm+ CALRwt. A panel of 45 myeloid neoplasm-associated genes was sequenced by NGS. Results. A total of 281 CALRm ET pts were identified from CRIMM (Florence, I), Quebec MPN Research Group centers' (Canada) and Mayo Clinic (Rochester, US) databases; 152 (54%), 101 (36%) and 28 (10%) were T1, T2 and T3 CALRm, respectively. Overall FU was 8.6y (0.3-39.4), median survival was not reached. Rate of death at 10y, 20y and 30y was 8%, 15% and 25%. MF transformation occurred in 50 pts (18%), AML in 2 (0.7%), 25 pts (8.9%) died. A major thrombotic event before or at ET diagnosis occurred in 17 (6.0 %) pts (14 arterial and 3 venous), whereas 28 pts (10.0%) had >1 major thrombosis during follow-up (53.6% arterial, 46.4% venous). Major bleeding occurred in 19 pts (6.8%; 16 at or before diagnosis). Ascertainment of correlation of CALRm VAF with predefined outcomes by continuous variable analysis (ROC curve) highlighted a significant correlation of VAF >60% with MF-free survival (MFS), with HR of 2.85 (95%CI, 1.4-5.6; P= .002. Fig. 1A). On the contrary, there was no impact of CALRm VAF as continuous variable on AML, thrombosis, bleeding and OS. We therefore used a threshold of >60% to compare main clinical and hematologic characteristics at diagnosis and outcomes during FU in pts categorized as CALR-high and CALR-low. Of all pts, 21 (7.5%) harbored a VAF >60%; of these, 52%, 19% and 29% were T1, T2, T3, respectively, compared to 54%, 37%, 8% of CALR-low (P= .008). We found no difference in age, gender, constitutional symptoms, splenomegaly, arterial and venous thrombosis at diagnosis and FU, IPSET revised risk stratification, and bleeding events. Hemoglobin was lower (12.8 g/dL (8.4-14.0) versus 13.6 (10.1-16.0); P=.02), while leukocytes and platelets did not differ. The proportion of pts with additional mutations in myeloid genes was significantly greater in CALR-high pts compared to CALR-low (66.7% vs 30.2%; P=0.01), as it was the proportion of pts with >2 mut myeloid genes (25% vs 11.6%, P=0.04). During FU, 52% of CALR-high pts (n=11) transformed to MF compared to 15% (n=39) of CALR-low (P<.0001); AML and death not differ. Anemia (<10g/dL) during the FU developed in 69% of CALR-high pts vs 18%, leukocytosis (>15x10 9/L) in 46% vs 8% and splenomegaly (greater than 5 cm from LCM) in 50% vs 12% (P<.0001 for all). The HR for anemia-free survival was 2.87 (95%CI, 1.3-6.3), for leukocytosis HR 3.71 (95%CI, 1.3-10.5) and splenomegaly HR 3.40 (95%CI, 1.2-9.2), all P<.01. MFS was significantly shorter in T1 (HR 2.0; P=0.04) or T3 (HR 2.7; P=0.03) using T2 as reference. Finally, we compared C ALR-mut, JAK2V617F mut and triple-negative (TN) ET pts. ROC analysis indicated a JAK2VAF >35% ( JAK2-high) as the best cutoff for shorter MFS. As in Fig. 1B, the MFS survival of CALR-high and JAK2-high was superimposable, and significantly shorter that in CALR/JAK2-low and TN pts. Conclusions. A CALR VAF >60% in pts with ET is associated with greater risk and shorter time to MF progression, development of anemia and splenomegaly. Similar findings in JAK2-high pts reinforce that that accumulation of mutated CALR and JAK2 alleles, evident since diagnosis, is detrimental for evolution to post-ET myelofibrosis. Longitudinal studies after diagnosis might provide further information about the kinetics of allele accumulation.

Abstract Introduction: Myelofibrosis -either primary (PMF) or post-polycythemia vera/essential thrombocythemia (collectively, secondary MF [SMF])- is characterized by biologic and clinical heterogeneity, with some patients (pts) presenting with features of myeloproliferation (MyP) and others exhibiting a myelodepletive (MyD) phenotype. Although not well defined, the latter is marked by cytopenias involving one or more hematopoietic lineages, in some respects mimicking a myelodysplastic or bone marrow (BM) failure syndrome. MyD features have been associated with poor prognosis in patients with MF, but cytopenias have been usually considered individually. In the current study, we aimed at investigating the phenotypic and prognostic correlates of a MyD phenotype in a large cohort of MF patients. Methods: After IRB approval, 704 consecutive patients with WHO-defined MF referring to CRIMM (Florence), were included in the study. There were 442 (63%) PMF and 262 (37%) SMF. Cytopenias at diagnosis were defined as follows: white blood cell (WBC) <4×10 9/L, hemoglobin (Hb) <11 g/dL for male and <10 g/dL for female, platelets (Plt) <100×10 9/L. A MyD phenotype was defined by the presence of at least one cytopenia in the absence of any increase of other blood cells (WBC >15×10 9/L, Hb >16.5 g/dL for male and >16 g/dL for female, Plt >450×10 9/L). Pts not included in the MyD group were considered as having a MyP phenotype. Mutational analysis by targeted NGS was available for 594/704 patients (PMF 368/442; SMF 226/262). Results: Overall, 166 pts were diagnosed as having a MyD MF, including 108 (24%) PMF and 58 (22%) SMF. Among PMF patients, leukopenia, sex-adjusted anemia and thrombocytopenia were present in 38%, 84% and 35%, respectively; in SMF, corresponding figures were 24%, 91% and 24%. Two or more cytopenias were found in 11% and 6% of PMF and SMF patients, respectively. In PMF, a MyD phenotype was associated with male gender (P=.0468), older age (P=.0002), lower peripheral blast count (P=.0006), higher prevalence of splenomegaly (P=0.0142), constitutional symptoms (P<.0001), and BM fibrosis grade ≥2 (P<.0001). The rates of thrombosis and bleeding were not different compared to MyP PMF. MyD pts were more likely to have very high risk (VHR) karyotype abnormalities (P=.0002) and to be triple negative (TN; P<.0001); there were no correlations with JAK2 mutation status and mutant burden, CALR and MPL mutations. Among non-driver mutations, a MyD phenotype was significantly enriched in ASXL1 (P=.0074), IDH1/2 (P=0.064), N/KRAS (P=.0014), U2AF1 (P<.0001), and CUX1 (P=.0002) mutations. Karyotype abnormalities (P=.0084), VHR cytogenetics (P=.0343), CBL (P=.0.171) and U2AF1 (P=.0148) mutations were significantly enriched in MyD pts with ≥2 cytopenias. On univariate analysis, OS was significantly shorter in pts with MyD vs MyP PMF (median, 55 vs 103 months, respectively; P<.0001), and not different between MyD pts with one (median, 65 months) and ≥2 (median, 44 months) cytopenias (Fig. 1A). After competing risk analysis, the cumulative incidence of leukemic transformation (LT) was not different between MyD and MyP phenotypes (16% vs 11% at 5 years, respectively). Phenotypic differences between MyD and MyP patients were less evident in SMF, a part for older age of the former (P=.0207). The molecular background was likewise different: a MyD feature was enriched in mutations in TP53 (P=.0024), U2AF1 (P<.0001), and SETBP1 (P=.0125). TP53 mutations were remarkably more frequent in MyD SMF pts with ≥2 cytopenias (19%). Pts with MyD SMF had a significantly shorter OS compared to the MyP counterpart (median, 44 vs 105 months; P<.0001). Median OS was significantly inferior in MyD patients with ≥2 cytopenias compared to one cytopenia (median, 27 vs 58 months, respectively; P<.0001) (Fig. 1B). The cumulative incidence of LT was not different: 16% vs 7% at 5 years, respectively, for SMF pts with MyD and MyP phenotype. Conclusion: The current study provides a comprehensive analysis of the MyD phenotype in pts with PMF and SMF, partly recapitulating findings of previous studies (Marcellino BK et al. Clin Lymphoma Myeloma Leuk 2020). We showed that the MyD phenotype is associated with high-risk clinical and molecular features, particularly in PMF, and correlates with inferior OS. Of interest, U2AF1 mutations emerged as a distinct molecular marker of MyD in both PMF and SMF, while mutations in TP53 appear prevalent in MyD SMF. Figure 1 Figure 1. Disclosures Vannucchi: Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees.