Tefferi, Ayalew

AbstractDisease OverviewRing sideroblasts (RS) are erythroid precursors with abnormal perinuclear mitochondrial iron accumulation. Two myeloid neoplasms defined by the presence of RS, include myelodysplastic syndromes with RS (MDS‐RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN‐RS‐T).DiagnosisMDS‐RS is a lower risk MDS, with single or multilineage dysplasia (MDS‐RS‐SLD/MLD), <5% bone marrow (BM) blasts, <1% peripheral blood blasts and ≥15% BM RS (≥5% in the presence of SF3B1 mutations). MDS/MPN‐RS‐T, now a formal entity in the MDS/MPN overlap syndromes, has diagnostic features of MDS‐RS‐SLD, along with a platelet count ≥450 × 109/L and large atypical megakaryocytes.Mutations and KaryotypeMutations in SF3B1 are seen in ≥80% of patients with MDS‐RS‐SLD and MDS/MPN‐RS‐T, and strongly correlate with the presence of BM RS; MDS/MPN‐RS‐T patients also demonstrate JAK2V617F (50%), DNMT3A, TET2 and ASXL1 mutations. Cytogenetic abnormalities are uncommon in both.Risk StratificationMost patients with MDS‐RS‐SLD are stratified into lower risk groups by the revised‐IPSS. Disease outcome in MDS/MPN‐RS‐T is better than that of MDS‐RS‐SLD, but worse than that of essential thrombocythemia (MPN). Both diseases are associated with a low risk of leukemic transformation.TreatmentAnemia and iron overload are complications seen in both and are managed similar to lower risk MDS and MPN. Luspatercept, a first‐in‐class erythroid maturation agent is now approved for the management of anemia in patients with MDS‐RS and MDS/MPN‐RS‐T. Aspirin therapy is reasonable in MDS/MPN‐RS‐T, especially in the presence of JAK2V617F, but the value of platelet‐lowering drugs remains to be defined.

AbstractPregnancy in the context of myeloproliferative neoplasms (MPN) poses unique fetal and maternal challenges. Current literature in this regard mostly involves essential thrombocythemia (ET) and less so polycythemia vera (PV) or myelofibrosis. In ET, live birth rate is estimated at 70% with first trimester fetal loss (˜ 30%) as the major complication. Risk of pregnancy‐associated complications is higher in PV, thus mandating a more aggressive treatment approach. Herein, we appraise the relevant literature, share our own experience and propose management recommendations. Aspirin therapy may offer protection against fetal loss; however the additive benefit of systemic anticoagulation or cytoreductive therapy, in the absence of high risk disease, is unclear. We recommend cytoreductive therapy in the form of interferon alpha in all high risk and select low‐risk ET and PV patients with history of recurrent fetal loss, prominent splenomegaly or suboptimal hematocrit control with phlebotomy. In addition, all women with PV should maintain strict hematocrit control <45% with the aid of phlebotomy. Systemic anticoagulation with low molecular weight heparin is advised in patients with history of venous thrombosis. Further clarification awaits prospective clinical trials that implement risk adapted therapeutic interventions.

AbstractDisease OverviewPrimary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell‐derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations. Additional disease features include bone marrow reticulin/collagen fibrosis, aberrant inflammatory cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.DiagnosisBone marrow morphology is the primary basis for diagnosis. Presence of JAK2, CALR, or MPL mutation, expected in around 90% of the patients, is supportive but not essential for diagnosis; these mutations are also prevalent in the closely related MPNs, namely polycythemia vera (PV) and essential thrombocythemia (ET). The 2016 World Health Organization classification system distinguishes “prefibrotic” from “overtly fibrotic” PMF; the former might mimic ET in its presentation. Furthermore, approximately 15% of patients with ET or PV might progress into a PMF‐like phenotype (post‐ET/PV MF) during their clinical course.Adverse MutationsSRSF2, ASXL1, and U2AF1‐Q157 mutations predict inferior survival in PMF, independent of each other and other risk factors. RAS/CBL mutations predicted resistance to ruxolitinib therapy.Adverse KaryotypeVery high risk abnormalities include −7, inv (3), i(17q), +21, +19, 12p‐, and 11q‐.Risk StratificationTwo new prognostic systems for PMF have recently been introduced: GIPSS (genetically‐inspired prognostic scoring system) and MIPSS70+ version 2.0 (MIPSSv2; mutation‐ and karyotype‐enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSSv2 includes, in addition, clinical risk factors. GIPSS features four and MIPSSv2 five risk categories.Risk‐adapted TherapyObservation alone is advised for MIPSSv2 “low” and “very low” risk disease (estimated 10‐year survival 56%‐92%); allogeneic hematopoietic stem cell transplant (AHSCT) is the preferred treatment for “very high” and “high” risk disease (estimated 10‐year survival 0%‐13%); treatment‐requiring patients with intermediate‐risk disease (estimated 10‐year survival 30%) are best served by participating in clinical trials. In non‐transplant candidates, conventional treatment for anemia includes androgens, prednisone, thalidomide, and danazol; for symptomatic splenomegaly, hydroxyurea and ruxolitinib; and for constitutional symptoms, ruxolitinib. Fedratinib, another JAK2 inhibitor, has now been FDA‐approved for use in ruxolitinib failures. Splenectomy is considered for drug‐refractory splenomegaly and involved field radiotherapy for non‐hepatosplenic EMH and extremity bone pain.New DirectionsA number of new agents, alone or in combination with ruxolitinib, are currently under investigation for MF treatment (ClinicalTrials.gov); preliminary results from some of these clinical trials were presented at the 2020 ASH annual meeting and highlighted in the current document.

Key Points Systemic immune microenvironment signatures in CMML indicate an altered T- and natural killer cell balance. CMML bone marrow dendritic cell aggregates associate with disease progression and systemic regulatory T-cell phenotypic switch.

Introduction: Mutations in the gene isocitrate dehydrogenase 2 (IDH2) occur in ~12-15% of patients with acute myeloid leukemia (AML). Enasidenib, an oral small molecule selective targeted inhibitor of IDH2 enzymes, was approved forIDH2mutated relapsed/refractory AML (RR-AML) in 2017 (Stein et. al., 2017). There is limited data regarding its efficacy and toxicity outside the context of clinical trials. Using Mayo Clinic's cohort of AML patients, we provide a real-world look at outcomes forIDH2mutated RR-AML patients treated with enasidenib. Methods: A total of 13 patients treated with enasidenib for RR-AML were identified, all of which experienced at least one relapse following induction chemotherapy. Response assessment was based on European Leukemia Net (ELN) 2017 response criteria.Complete blood counts including blast percentage and transfusion dependency were obtained at AML diagnosis, initiation of enasidenib, 2 months and 6 months following initiation of therapy. Transfusion dependency was defined by the need for either a red cell or platelet transfusion within 4 weeks of the designated time frame. We compared the clinical characteristics of patients who achieved complete response (CR) (n=4) to those not achieving CR (n=9), using the Mann-Whitney U test for numerical variables and the Fischer's Exact test for quantitative data. Results: The median age at diagnosis of our 13 patients was 68 years (range 60-82), with a male predilection (n=11) (Table 1). Cytogenetic and molecular genetic findings are provided in Table 2. Complete response (CR) was achieved in 4 (30.7%) patients by cycle 2 and 2 of those patients (50%) proceeded to an allogeneic hematopoietic stem cell transplant (AHSCT). The median time from diagnosis to initiation of treatment for patients in CR was 3.5 months (range 1-7), and for patients not achieving CR was 13 months (range 6-53; p=0.048), with median time of follow up after treatment initiation of 23.5 months (range, 5-36) and 7 months (range, 1-14), respectively. Among 8 patients who were transfusion dependent at baseline, all the CR patients (2/2) achieved red blood cell and platelet transfusion independence 6 months after treatment, instead only (3/6) 50% of those not in CR achieved transfusion independence (p=0.028). An initial trajectory of improvement in counts is noted from the time of diagnosis to the 2 month mark post treatment with 75% of the responder cohort showing improvement in counts which was durable through the 6 month mark, whereas 55% of those that did not respond had worsening counts at month 2 and died prior to 6 month follow up. At the time of data cut-off, the median duration of CR was 14 months (range, 2-33), with 3 of 4 (75%) of responders maintaining CR. Figure 1 details overall responses and outcomes in all 13 patients. None of the patients in our study experienced differentiation syndrome. Five patients were hospitalized in the course of treatment for infectious complications. Two patients were noted to have hyperbilirubinemia however there was no clear indication that this was secondary to enasidenib Median overall survival for all 13 patients was 21 months (range, 6-53 months) with leukemia free survival of 7 months (range, 5-19 months). Furthermore, median overall survival for patients in CR was 27 months (range, 6-42), and those not in CR was 16 months (range, 6-53) (p=0.20). In addition, we observed that 75% of patients who attained CR are alive compared to 11.1% of those not in CR (p = 0.052). Conclusion: We demonstrate a superior CR rate of 30.7% with enasidenib amongstIDH2mutated RR-AML patients compared with clinical trial data showing CR rate of 19.6% (Stein et. al., 2019) despite our patients being heavily pre-treated with median number of two prior therapies (range; 1-5) including prior AHSCT in 2 patients. Moreover, a subset of patients (2 of 4 in CR) were able to undergo ASCHT. Finally, the achievement of CR at 2 months after initiation of therapy serves as an appropriate time point for response assessment. Disclosures No relevant conflicts of interest to declare.

Introduction Clonal cytopenias of undetermined significance (CCUS) is defined by the presence of somatic driver mutations/copy number variations in hematopoietic cells in patients with low blood counts, in the absence of morphological evidence for myeloid neoplasms. Patients with CCUS are often symptomatic and can be transfusion dependent (TD), with high rates of progression to myeloid neoplasms, especially myelodysplastic syndromes (MDS). In addition, similar to MDS, there are reports of CCUS patients responding to hypomethylating agents. Due to the lack of a formal diagnosis/morphological dysplasia, CCUS patients are often denied therapies or clinical trial enrollment. We carried out this study to validate our hypothesis that CCUS shares similar clinical and survival characteristics with lower risk MDS (LR-MDS). Methods CCUS patients were prospectively identified from the clonal hematopoiesis clinic, whereas LR-MDS patients were retrospectively identified from our institutional database. LR-MDS was defined as very low, low and intermediate risk MDS based on the R-IPSS categorization. Baseline demographics, blood counts, bone marrow (BM) morphology, cytogenetics, and NGS results were abstracted. Transfusion dependency was defined as requiring at least one unit of red cell or platelets every 4 weeks. The Mann-Whitney-U and Fischer's exact test were used to compare quantitative and qualitative data in subgroups. Kaplan-Meier overall survival (OS) estimates were used for survival analysis and compared using the log-rank test. Results 186 patients were included in the study; 74 (40%) with CCUS and 112 (60%) with LR-MDS, median age 66 years, with 63% being male (Table 1). In the CCUS group, 93% had one or more mutations (67% &gt;1 mutation) detected by NGS, while 7% had clonal cytogenetic abnormalities. Common mutations in CCUS included TET2 (30%), SRSF2 (20%), DNMT3A (13%) and ASXL1 (11%); with 28% of patients being red cell TD and 15% being platelet TD. On application of the R-IPSS stratification, 40%, 45%, 12% and 3% were in the very low, low, intermediate and high risk categories, respectively. LR-MDS subtypes included MDS-RS (50%), MDS-MLD (21%), MDS-EB (10%), MDS del5q (7%), and MDS-U (12%). SF3B1 mutations were seen in 67% (95% of MDS-RS), while TET2 and DNMT3A mutations were seen in 29% and 21%, respectively. 60% of LR-MDS patients had &gt;1 mutation. 44% were red cell TD, while 10% were platelet TD. In comparison to patients with CCUS, LR-MDS patients were more likely to have higher white blood cell counts (p=0.002), higher neutrophil counts (p=0.009), higher platelet counts (p&lt;0.001), be red cell TD (p=0.031), have BM ring sideroblasts (p&lt;0.001), have higher BM blast% (p=0.004) and carry SF3B1 mutations (p&lt;0.001); whereas CCUS patients were more likely to have higher monocyte counts (p=0.009) and more likely to carry IDH1 (p=0.005), ZRSR2 (p=0.005) and ATM (p=0.012) mutations. Importantly there were no differences with regards to R-IPSS cytogenetic risk groups, R-IPSS prognostic categories, platelet TD, and mutations involving TET2, DNMT3A, SRSF2 and ASXL1 and TP53. Notably signal pathway mutations and mutations involving tumor suppressor genes were infrequent (&lt;5%) in both groups. The LR-MDS patients had a longer median follow up (53 vs 15 months) and at last follow up 72 (64%) and 11 (15%) deaths had been documented in the LR-MDS and CCUS groups respectively. 13 (18%) CCUS patients progressed to MDS (10) and AML (3) over a median of 15 months, while 9 (8%) LR-MDS patients progressed to higher grade MDS (1) and AML (8), respectively (median follow up 53 months). There was no difference in the median survival between CCUS (median OS not reached) versus LR-MDS (median OS 8.3 years) (p=0.372, Figure 1). Conclusion In spite of subtle phenotypic/molecular differences between LR-MDS and CCUS, both entities had similar prognostication, distribution of high risk mutations and survival outcomes. Within a short follow-up, 18% of CCUS patients progressed to MDS/AML, indicating that regardless of the absence of dysplasia these entities are a continuum of myeloid neoplasms. In order to improve access to treatments and clinical trial opportunities, we recommend that close consideration be given to consider CCUS as a MDS subtype. Disclosures Shah: Dren Bio: Consultancy.

Background Clonal cytopenia of undetermined significance (CCUS) is a newly described entity with a high probability to progress into myeloid disorders upon follow-up (Malcovati et al, Blood 2017). Little data is known on how to effectively treat patients with CCUS. We hereby describe a single institution experience in managing symptomatic CCUS patients. Methods Patients who had CCUS and underwent active treatment were identified after receiving IRB approval. CCUS diagnosis was rendered if patients had non-diagnostic bone marrow biopsy evaluation combined with evidence of pathogenic myeloid somatic mutation using our institution next generation sequencing (NGS) panel (OncoHeme, Mayo Clinic). "Symptomatic patients" is determined by patients who need therapy beyond blood transfusion. Treatment type is based on physicians' choice. Clinical and lab results were collected. Response and progression were graded based on the MDS IWG 2006 criteria. The date of treatment initiation was used for overall survival (OS) and progression (either to myeloid neoplasm or worsening cytopenias) free survival (PFS) calculation. Stata 14.1(StatCorp) was used for data analysis. Results 1) Cohort characteristics: Between 2015 and 2020, 24 patients met inclusion criteria with median age of 72 years (range: 24-87). Twenty (83%) were men. 15 (63%) were white, 1 (4%) African American, 1 (4%) Native American and 7 unknown (33%). Eighty percent had ECOG PS≤1. Four (17%) patients had prior other hematology disorders and 3 (13%) had solid tumor. Two (8%) patients had previous radiation therapy, 2 (8%) received chemotherapy and 1 (4%) received allogeneic stem cell transplantation. At the time of treatment, the median of hemoglobin was 8.9 (range 6.8-13.7) g/dL, white blood cell 2.9 (range 1.4-12.3) *109/L, and platelet 76 (range 8-407) *109/L. Red blood cell (RBC) and platelet transfusion dependency rate were 54% and 29%, respectively. We identified 23 different mutations. Most common mutations occurred in SRSF2 (N=5, 21%), TET2 (N=5, 21%), U2AF1 (N=5, 21%), and TP53 (N=4, 17%). Ten (42%) patients had 1 mutation, and 14 (58%) had ≥2 mutations. Treatment included hypomethylating agents (HMA) (N=10, 42%), growth factors (N=11, 46%), steroid (N=4, 17%), testosterone (N=2, 8%), cyclosporine (N=2, 8%), rituximab (N=1, 4%), immunoglobulin (N=1, 4%), vitamin B12 and iron (N=1, 4%). Seven (29%) patients received ≥2 treatments. Median follow up duration was 17.5 months (range 8.9-26.1). Median time from the diagnosis to treatment was 2.1 months (range 0-26.8). 2) Molecular correlation with response The overall response rate (RR) was 50% (hematological or symptomatic improvement). Most responders (67%) were treated with HMA (p=0.013). HMA treatment effect was not significantly associated with DNA methylation genes (DNMT3A, IDH1, IDH2 and TET2, all p&gt;0.05). The RR was 100% for the three patients with IDH1 mutation (treated with HMA, steroid and erythropoietin stimulating agent (ESA), respectively). The RR was 100% for the 3 patients with ZRSR2 mutation (2 HMA, 1 testosterone). The RR was 0% for 3 patients with SF3B1 mutation (1 testosterone and ESA, 1 vitamin B12 and iron, and 1 HMA). The number of mutations had no impact on RR (p=0.41). Table demonstrates the RR for each treatment. 3) Survival and progression outcome At the last day of follow up, RBC and platelet transfusion dependency rate were 38% and 25%, respectively. The median PFS was 16.9 months (95% CI: 7.5-65.3). Six patients (25%) progressed to myeloid malignancy with 4 myelodysplastic syndrome (MDS) and 2 acute myeloid leukemia (AML). Five patients progressed with worsening cytopenias. Among the 4 MDS patients, they had SF3B1, TET2, and ASXL1 mutations at the diagnosis of CCUS. Within the 2 AML pts, 1 had RUNX1 mutation, 1 had BCOR, DNMT3A, PHF6, RUNX1, SF3B1, STAG2, and TET2 mutations at the diagnosis of CCUS. The median OS was not reached with an estimated 2 year OS 77%. Three (13%) patients progressed with cytopenia and died. Their NGS at CCUS diagnosis showed ASXL1, TP53 and U2AF1 mutations, respectively. Conclusion Patients with CCUS responded to available treatments used for myeloid diseases. HMA were effective in this cohort. Mutation profile may have an impact on treatment response. Studies of larger cohorts are needed to validate our findings. Additionally, development of response and progression criteria would be helpful for such patients for reporting treatment outcomes. Disclosures Shah: Dren Bio: Consultancy.

Introduction: Myeloproliferative neoplasms (MPN), including primary myelofibrosis (PMF), essential thrombocythemia (ET) and polycythemia vera (PV), have a propensity to evolve into blast phase myeloproliferative neoplasm (BP-MPN) with a 20-year incidence rate of 9.3 %, 3.9% and 2.6%, respectively. (Szuber et al., 2019)Treatment options for BP-MPN are limited and the prognosis of these patients is dismal with a median survival of only 3.6 months and 5-year survival rate of &lt;5%.(Tefferi et al., 2018) Considering the recent reported data on the efficacy of venetoclax when combined with hypomethylating agents (HMA) in acute myeloid leukemia (AML) in both relapsed/refractory and newly diagnosed unfit patients, we have extended such combination therapy for patients with BP-MPN. Methods: We retrospectively analyzed 14 consecutive BP-MPN patients who received venetoclax plus HMA therapy between August 2018 and June 2020. We collected data regarding clinical characteristics of chronic phase MPN and BP-MPN, cytogenetic and leukemia mutation profile, efficacy and outcome. Oral venetoclax was administered in combination with azacitidine 75 mg/m2 days 1-7 (5 patients) or decitabine 20 mg/m2 days 1-5 (9 patients). Venetoclax dose was adjusted based on drug interactions particularly with azole antifungal prophylaxis. Diagnostic, risk and response assignments were according to the 2017 European LeukemiaNet (ELN) criteria.(Döhner et al., 2017) Minimal residual disease (MRD) assessment by flow cytometry, karyotype or next-generation sequencing (NGS) was performed in a subset of patients. Results: Patient characteristics at time of leukemic transformation, treatment details, response rates and overall outcome are shown in Table 1. Median age of patients was 67 years (range 48-81) with poor-risk cytogenetics in 69% of patients. JAK2 was mutated in 10 patients (71%) and CALR in 2 (14%); other mutations included TP53 in 5 patients (36%), TET2 in 4 (29%), KRAS in 3 (21%), IDH1/2 in 3 (21%), ASXL1 in 2 (14%) and U2AF1 in 2 (14%). Eight patients (57%) received venetoclax and HMA combination therapy upfront for their BP-MPN, 2 patients (14%) had failed HMA therapy previously and one patient had prior allogeneic hematopoietic stem cell transplant (AHSCT). Two patients (14%) presented with myeloid sarcoma; one of these two patients documented partial resolution of the extramedullary tumor by imaging studies, after treatment with venetoclax plus HMA. Among the remaining 12 patients, overall response rate (ORR) was 42% (n=5) and included complete remission (CR) in 3 patients (25%) and partial remission (PR) in another 2 (17%). The best response to therapy was seen after a median of 1 month (range, 1-2). Among 3 CR responders, 2 (66.6%) had minimal residual disease negative by NGS and not evidence of preceding MPN, then they successfully transitioned to AHSCT, while the third CR patient at the time of best response showed persistence of the TP53 mutation. Additionally, one PR patient subsequently relapsed and received salvage chemotherapy followed by AHSCT. (Table 2) Although data is limited by the small cohort and short follow up when the outcome of patients treated with venetoclax in combination with HMA were compared to Mayo Clinic's historical control of patients with BP-MPN treated with HMA alone (n=26) or intensive chemotherapy (n=69), there was higher CR rate in patients treated with venetoclax and HMA (25%) compared to those receiving HMA alone (4%; p=0.048) but not to those receiving intensive chemotherapy (35%; p&lt;0.0001). Moreover, the intensive chemotherapy cohort showed 24% of CR with incomplete hematologic recovery (CRi) not seen in patients receiving HMA alone or HMA with venetoclax (Figure1). Conclusions: The relatively high rate of complete response observed in our patients with BP-MPN were similar to those reported in a pivotal study of elderly unfit AML patients treated upfront with venetoclax + HMA with overall response rates of 68%.(DiNardo et al., 2019) Furthermore, responders included patients with adverse molecular risk factors who usually respond poorly to conventional chemotherapy (i.e. TP53 mutated patients). Our observations provide preliminary evidence for the potential efficacy of venetoclax and HMA combination therapy in BP-MPN with the goal of achieving CR/CRi followed by consolidative AHSCT wherever possible to provide durable remission and meaningful survival benefit. Disclosures Foran: Agios: Honoraria, Research Funding; Trillium: Research Funding; Takeda: Research Funding; Kura Oncology: Research Funding; Aptose: Research Funding; Aprea: Research Funding; Actinium: Research Funding; Boehringer Ingelheim: Research Funding; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Revolution Medicine: Consultancy; Xencor: Research Funding; H3Biosciences: Research Funding.