Tefferi, Ayalew

Abstract Disease Overview Polycythemia vera (PV) is a JAK2 ‐mutated myeloproliferative neoplasm characterized by clonal erythrocytosis; other features include leukocytosis, thrombocytosis, splenomegaly, pruritus, constitutional symptoms, microcirculatory disturbances, and increased risk of thrombosis and progression into myelofibrosis (post‐PV MF) or acute myeloid leukemia (AML). Diagnosis A working diagnosis is considered in the presence of a JAK2 mutation associated with hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women; morphologic confirmation by bone marrow examination is advised but not mandated. Cytogenetics Abnormal karyotype is seen in 15%–20% of patients with the most frequent sole abnormalities being +9 (5%), loss of chromosome Y (4%), +8 (3%), and 20q− (3%). Mutations Over 50% of patients harbor DNA sequence variants/mutations other than JAK2 , with the most frequent being TET2 (18%) and ASXL1 (15%). Prognostically adverse mutations include SRSF2, IDH2, RUNX1 , and U2AF1 , with a combined incidence of 5%–10%. Survival and Prognosis Median survival is ⁓15 years but exceeds 35 years for patients aged ≤40 years. Risk factors for survival include older age, leukocytosis, abnormal karyotype, and the presence of adverse mutations. Twenty‐year risk for thrombosis, post‐PV MF, or AML are ⁓26%, 16% and 4%, respectively. Risk Factors for Thrombosis Two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). Additional predictors for arterial thrombosis include cardiovascular risk factors and for venous thrombosis higher absolute neutrophil count and JAK2 V617F allele burden. Treatment Current goal of therapy is to prevent thrombosis. Periodic phlebotomy, with a hematocrit target of <45%, combined with once‐ or twice‐daily aspirin (81 mg) therapy, absent contraindications, is the backbone of treatment in all patients, regardless of risk category. Cytoreductive therapy is reserved for high‐risk disease with first‐line drugs of choice being hydroxyurea and pegylated interferon‐α and second‐line busulfan and ruxolitinib. In addition, systemic anticoagulation is advised in patients with venous thrombosis history. Additional Treatment Considerations At the present time, we do not consider a drug‐induced reduction in JAK2 V617F allele burden, which is often incomplete and seen not only with peg‐IFN but also with ruxolitinib and busulfan, as an indicator of disease‐modifying activity, unless accompanied by cytogenetic and independently‐verified morphologic remission. Accordingly, we do not use the specific parameter to influence treatment choices. The current review also includes specific treatment strategies in the context of pregnancy, splanchnic vein thrombosis, pruritus, perioperative care, and post‐PV MF.

Abstract We surveyed the performance of ponatinib, as salvage therapy, in a real-world setting of chronic phase chronic myeloid leukemia (CML-CP). Among 55 consecutive patients (median age 49 years) with relapsed/refractory CML-CP, 35 (64%) had failed ≥ 3 tyrosine kinase inhibitors (TKIs), 35 (64%) were pre-treated with nilotinib, and 14 (28%) harbored ABL1T315I. At start of ponatinib (median dose 30 mg/day), 40 patients were already in complete hematologic (CHR), 4 in complete cytogenetic (CCyR), 3 in major molecular (MMR) remission, while 8 had not achieved CHR (NR). Ponatinib improved the depth of response in 13 (33%), 3 (75%), 2 (66%), and 4 (50%) patients with CHR, CCyR, MMR, and NR, respectively (p = 0.02). At a median follow-up of 42 months, 13 (23%) deaths, 5 (9%) blast transformations, and 25 (45%) allogeneic transplants were recorded. Five/10-year post-ponatinib survival was 77%/58% with no significant difference when patients were stratified by allogeneic transplant (p = 0.94), ponatinib-induced deeper response (p = 0.28), or a post-ponatinib ≥ CCyR vs CHR remission state (p = 0.25). ABL1T315I was detrimental to survival (p = 0.04) but did not appear to affect response. Prior exposure to nilotinib was associated with higher risk of arterial occlusive events (AOEs; 11% vs 0%; age-adjusted p = 0.04). Ponatinib starting/maintenance dose (45 vs 15 mg/day) did not influence either treatment response or AOEs. Our observations support the use of a lower starting/maintenance dose for ponatinib in relapsed/refractory CML-CP but a survival advantage for deeper responses was not apparent and treatment might not overcome the detrimental impact of ABL1T315I on survival. The association between prior exposure to nilotinib and a higher risk of post-ponatinib AOEs requires further validation.

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.

7059 Background: TP53-mutated ( TP53mut) myeloid neoplasms (MN) are aggressive leukemia with poor survival. A subset of TP53mut MN is preceded by TP53mut CCUS that is conventionally considered to be high-risk premalignant condition, though evidence supporting the notion is lacking. We studied outcomes of TP53mut CCUS compared to TP53 wild-type ( TP53wt) CCUS. Methods: Mayo Clinic Molecular Hematology Database (N=7593) was queried to identify patients (pts) harboring pathogenic variant(s) in exons 4-11 of the TP53 gene with ≥2% variance allele frequency (VAF). CCUS was defined using the 5th edition of the WHO Classification for MN. Results: Of 457 pts with TP53mut, 29 (5.9%) had TP53mut CCUS. The median age at diagnosis was 67 years, 17 (59%) were female, and 20 (69%) had received cytotoxic therapies. One and ≥2 TP53mut were seen in 26 (89.6%) and 3 (10.3%) pts, respectively. Median TP53mut VAF was 9% (range 3-42), 3 had TP53mut VAF ≥20%, and 4 (14%) had non-MDS defining cytogenetic anomalies. Of 16 pts with available follow up evaluation (median interval 22 months, Table), 3 (10.3%) progressed to TP53mut MN at 5, 13, and 14 months from diagnosis. We next compared outcomes of TP53mut CCUS to TP53wt CCUS (n=138). The proportion of pts developing MN was not different between TP53wt and TP53mut CCUS (18.1 vs 10.3%, P= .42). Progression free survival of TP53mut CCUS was comparable to TP53wt CCUS at 1- (77 vs 83%), 2- (67 vs 67%), and 5-years (67 vs 59%, P=.9). Similarly, overall survival of TP53mut vs TP53wt CCUS at 1- (81 vs 89%), 2- (76 vs 76%), and 5-years (76 vs 67%) was comparable ( P= .94). Conclusions: In contrast to the prevalent notion, TP53mut was not associated with a higher risk of MN progression or mortality compared to TP53wt CCUS. Majority of TP53mut clones showed remarkable stability over years. [Table: see text]