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Following the observation of interleukin 3 receptor α chain (IL-3Rα; CD123) upregulation on leukemia stem cells (LSCs) almost two decades ago, targeted treatment via CD123-diptheria toxin conjugates has now been tested in patients with diverse myeloid malignancies. Targeted eradication of LSCs could result in effective treatments for many challenging diseases initiated by these cells. Consequently, considerable effort has been directed toward targeting CD123 as a potential strategy for treating patients with hematologic malignancies in which CD123 is overexpressed. However, these therapies have had limited success so far, highlighting the need for suitable criteria to identify patients who could benefit from them. Given the diversity in CD123 expression across different hematologic malignancies, understanding CD123 expression patterns and the functional pathogenetic significance is crucial. Here, we review the methodologies available for CD123 assessment and discuss the biological and clinical characteristics of patients for whom CD123-targeting therapies may have a clinical impact.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive myeloid malignancy. We report long-term results, including data from the continued access phase, of the largest prospective BPDCN trial evaluating the CD123-targeted therapy tagraxofusp (TAG) in adults with treatment-naive and relapsed/refractory BPDCN. The primary outcome was complete response (CR) + clinical CR (CRc: CR with residual skin abnormality not indicative of active disease). Eighty-four (65 treatment-naive and 19 relapsed/refractory) of 89 patients received TAG 12 μg/kg once daily; the median follow-up was 34.0 months. For treatment-naive patients, the overall response rate was 75%; 57% achieved CR + CRc. The median time to remission was 39 (range, 14-131) days, and the median CR + CRc duration was 24.9 (95% CI, 3.8 to not reached) months. Nineteen patients (51%) with CR + CRc were bridged to stem-cell transplant, with a median CR + CRc duration of 22.2 (range, 1.5-57.4) months. Most common adverse events were increased alanine (64%) or aspartate (60%) aminotransferase and hypoalbuminemia (51%); most occurred in cycle 1 and were transient. Capillary leak syndrome occurred in 21% of patients (grade ≥ 3: 7%). In first-line patients with BPDCN, TAG monotherapy resulted in high and durable responses, allowing many to bridge to stem-cell transplant. TAG was generally well-tolerated with a predictable and manageable safety profile.

Despite much of the past 2 years being engulfed by the devastating consequences of the SAR-CoV-2 pandemic, significant progress, even breathtaking, occurred in the field of chronic myeloid malignancies. Some of this was show-cased at the 15th Post-American Society of Hematology (ASH) and the 25th John Goldman workshops on myeloproliferative neoplasms (MPN) held on 9th-10th December 2020 and 7th-10th October 2021, respectively. The inaugural Post-ASH MPN workshop was set out in 2006 by John Goldman (deceased) and Tariq Mughal to answer emerging translational hematology and therapeutics of patients with these malignancies. Rather than present a resume of the discussions, this perspective focuses on some of the pivotal translational hematology and therapeutic insights in these diseases.

Context: Mutations in the FLT3 tyrosine kinase and in IDH1/IDH2 (collectively IDHm) co-occur in up to 30% of adults with acute myeloid leukemia (AML). SEL24/MEN1703 is an orally available, first-in-class, dual PIM/FLT3 kinase inhibitor. Preliminary results from the phase 1/2 first-in-human DIAMOND-01 trial (NCT03008187) demonstrated antitumor activity of single-agent SEL24/MEN1703 in adult patients with relapsed/refractory (R/R) IDHm AML, where 3 of 8 IDHm patients responded. Objective: To report the first safety and efficacy results from an additional expansion cohort of the DIAMOND-01 trial in 20 patients with R/R IDHm AML. Design: DIAMOND-01 is a phase 1/2, open-label, multicenter study consisting of 2 parts: dose escalation and cohort expansion, including an additional expansion cohort (IDHm) that is ongoing. Patients: Patients with R/R IDHm AML and no standard therapeutic options were eligible. Intervention(s): Patients received the recommended dose of 125 mg SEL24/MEN1703 orally, once daily for 14 days over a 21-day cycle until disease progression or unacceptable toxicity. Main Outcome Measure(s): The number and frequency of adverse events (AEs; primary) and overall response rate (ORR; secondary). Results: As of 10 January 2022, 14 patients were enrolled in the IDHm cohort. Seven patients had IDH2, 1 had IDH1/2, and 4 had IDH1 mutations. Two patients had a concomitant FLT3-ITD mutation. Safety data (N=12) showed that grade ≥3 TEAEs (≥10% of patients) were pneumonia (33%) and asthenia (17%), both unrelated to the study drug. Of the 7 patients who completed ≥1 treatment cycle and had ≥1 post-baseline assessment or clear disease progression, ORR was 28.6%; 1 patient achieved a complete response with incomplete blood count recovery at cycle 3 and underwent hematopoietic stem cell transplant, and 1 patient had a partial response at cycle 4 (confirmed at cycle 7 and still on treatment). Among the 7 remaining patients, 3 discontinued before completion of cycle 1 without progression or response, and 4 patients are ongoing and have not yet undergone post-baseline assessments. Conclusions: SEL24/MEN1703 had a manageable safety profile and single-agent activity in adult patients with R/R IDHm AML and may be a feasible therapeutic option in this difficult-to-treat population.

© 2021 the Author(s)., During the past few years, our understanding of molecular mechanisms and cellular interactions relevant to malignant blood cell disorders has improved substantially. New insights include a detailed knowledge about disease-initiating exogenous factors, endogenous (genetic, somatic, epigenetic) elicitors or facilitators of disease evolution, and drug actions and interactions that underlie efficacy and adverse event profiles in defined cohorts of patients. As a result, precision medicine and personalized medicine are rapidly growing new disciplines that support the clinician in making the correct diagnosis, in predicting outcomes, and in optimally selecting patients for interventional therapies. In addition, precision medicine tools are greatly facilitating the development of new drugs, therapeutic approaches, and new multiparametric prognostic scoring models. However, although the emerging roles of precision medicine and personalized medicine in hematology and oncology are clearly visible, several questions remain. For example, it remains unknown how precision medicine tools can be implemented in healthcare systems and whether all possible approaches are also affordable. In addition, there is a need to define terminologies and to relate these to specific and context-related tools and strategies in basic and applied science. To discuss these issues, a working conference was organized in September 2019. The outcomes of this conference are summarized herein and include a proposal for definitions, terminologies, and applications of precision and personalized medicine concepts and tools in hematologic neoplasms. We also provide proposals aimed at reducing costs, thereby making these applications affordable in daily practice., This project was supported by the Austrian Science Fund (FWF)—grants F4701-B20 and F4704-B20. UJ was supported by grant LS16-034 from the Vienna Science and Technology Fund (WWTF).

This review reflects the presentations and discussion at the 14th post-ASH International Workshop on Chronic Myeloproliferative Malignancies, which took place on the 10th-11th December 2019, immediately after the 61st American Society of Hematology (ASH) Annual Meeting in Orlando, Florida. Rather than present a resume of the proceedings, we address some of the topical translational science research and clinically relevant topics in detail. We consider how recent studies using single-cell genomics and other molecular methods reveal novel aspects of hematopoiesis which in turn raise the possibility of new therapeutic approaches for patients with myeloproliferative neoplasms (MPNs). We discuss how alternative therapies could benefit patients with chronic myeloid leukemia (CML) who develop BCR-ABL1 mutant subclones following ABL1-tyrosine kinase inhibitor therapy (TKIs). In MPNs, we focus on efforts beyond JAK-STAT and the merits of integrating activin receptor ligand traps, interferon-α, and allografting in the current treatment algorithm for patients with myelofibrosis (MF). This article is protected by copyright. All rights reserved.

Clinically chronic myeloproliferative neoplasms are biphasic or triphasic diseases that are usually diagnosed in the initial ‘chronic’, ‘indolent’, or ‘stable’ phase and then spontaneously evolve after some years into an advanced phase. In patients with chronic myeloid leukaemia, the advanced phase can sometimes be subdivided into an earlier accelerated phase and a later blast phase resembling acute leukaemia. Patients with essential thrombocythaemia and polycythaemia vera transform initially to myelofibrosis and then to acute myeloid leukaemia (AML). Rarely they transform directly from the initial indolent phase to AML; patients with primary myelofibrosis also transform directly to AML. Although much is known about the molecular biology and genomic landscape of the initial phases, the molecular basis of disease progression and transformation remains obscure. The clinical management of transformed disease is generally difficult, and most patients tend to have a poor prognosis. This chapter reviews what is known of the mechanisms underlying the transformation of these myeloproliferative neoplasms from a chronic phase to frank leukaemia and also discusses the current and future treatment strategies.

Essential thrombocythaemia is a classic myeloproliferative neoplasm characterized by thrombocytosis, increased risk of thrombotic and/or haemorrhagic complications, and a trend to transformation to myelofibrosis and acute leukaemia. Mutations in JAK2, CALR, and MPL genes besides bone marrow histology are crucial elements of diagnosis. Treatment is aimed to prevent the appearance of thrombotic complications that are the main cause of morbidity and mortality. Accordingly, thrombosis risk stratification is of the utmost importance to select the appropriate treatment. Antiplatelet therapy as primary antithrombotic prophylaxis in low-risk patients should be tailored according to the existence of extreme thrombocytosis and presence of JAK2V617F mutation and/or cardiovascular risk factors. Cytoreductive treatment options are discussed with reference to results of randomized clinical trials. Practical approach to unusual and risk situations as surgery, pregnancy, and paediatric essential thrombocythaemia are also reviewed.

The history of haematological malignancies appears to have begun in the sixteenth century as a result of astute clinical observations and the invention of medical microscopy. In the nineteenth century, the use of aniline-based dyes to stain human tissues facilitated the initial recognition of leukaemias, lymphomas, and myelomas as distinct nosological entities. The first detailed description of what is now referred to as chronic myeloid leukaemia, appeared in 1845, and the other ‘classic’ myeloproliferative neoplasms thereafter. Major progress in the therapy and the understanding of these malignancies, however, did not occur until the mid-twentieth century. Since the mid-1990s, these efforts have accelerated remarkably, resulting in the successful introduction of molecularly targeted therapies, and along with increased affordability and reliability of genomic profiling, have helped to usher in the era of precision medicine. In this chapter, we present a brief history of the biological and therapeutic milestones pertaining to myeloproliferative neoplasms.

Chronic myeloid leukaemia (CML) was recognized in the 1970s by Janet Rowley to be a genetically simple malignancy; resulting as a consequence of a balanced translocation between chromosome 9 and 22. This provided vital insights into the molecular aberration, in the 1990s, which ushered in the current ‘precision medicine’ era, not only for patients of CML, but for cancers in general. As a result, today, a personalized treatment algorithm is available for all newly diagnosed patients with CML. Treatment involves a choice of three first-line orally administered tyrosine kinase inhibitors (TKIs) and two effective next-line TKIs that should be used based on risk stratification, comorbidities, the side effects profile, and the BCR-ABL1 genotype. Regardless of the initial choice of TKI, the vast majority of patients achieve a durable complete cytogenetic remission, with a lifespan approaching that of the general population. In most instances the medication must be continued indefinitely, and a principal challenge now, is to develop strategies to stop TKIs safely and effectively. Challenges remain in how to achieve optimal monitoring of patients with CML on treatment and in achieving a better understanding of the mechanisms and treatment of patients with advanced phase disease. This chapter addresses these questions as well as the concomitant topical issues in CML.

Polycythaemia vera (PV) is a clonal stem cell disorder characterized by erythrocytosis and associated with burdensome symptoms, risk of thrombohaemorrhagic complications, and transformation to myelofibrosis and acute myeloid leukaemia. Diagnostic criteria are very recently revised by the World Health Organization (WHO) based on haemoglobin and haematocrit levels, bone marrow morphology consistent with trilineage proliferation and presence of the JAK2 V617 mutation. Cytoreductive therapy is indicated in patients at increased risk of thrombosis. Hydroxyurea (HU) remains the most commonly used first-line cytoreductive therapy and interferon (IFN) is used either at failure of HU or in selected patients as first-line therapy. A recent phase 3 trial has shown the superiority of the JAK1/2 inhibitor ruxolitinib in comparison to best available treatment in HU-intolerant or resistant patients.

The myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are haematologically diverse stem cell malignancies sharing phenotypic features of both myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) that display a paradoxical bone marrow phenotype hallmarked by myeloid proliferation in the context of bone marrow dysplasia and ineffective haematopoiesis. The unfolding MDS/MPN genomic landscape has revealed numerous mutations in signalling genes, such as CBL, JAK2, NRAS, KRAS, CSF3R, and others involving the spliceosome complex. These observations suggest that comutation of genes involved in dysplasia and bone marrow failure along with those of cytokine receptor signalling may, in part, explain the dual MDS/MPN phenotype. The respective MDS/MPN diseases are identified by the type of myeloid subset which predominates in the peripheral blood. Currently there are no standard treatment recommendations for most patients with MDS/MPN. To optimize efforts to improve the management and disease outcomes, it is essential to identify meaningful clinical and biologic endpoints and standardized response criteria for clinical trials.

Rearrangements involving the neurotrophic receptor kinase genes (NTRK1, NTRK2, and NTRK3; hereafter referred to as TRK) produce oncogenic fusions in a wide variety of cancers in adults and children. Although TRK fusions occur in fewer than 1% of all solid tumors, inhibition of TRK results in profound therapeutic responses, resulting in Breakthrough Therapy FDA approval of the TRK inhibitor larotrectinib for adult and pediatric patients with solid tumors, regardless of histology. In contrast to solid tumors, the frequency of TRK fusions and the clinical effects of targeting TRK in hematologic malignancies are unknown. Here, through an evaluation for TRK fusions across more than 7,000 patients with hematologic malignancies, we identified TRK fusions in acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), histiocytosis, multiple myeloma, and dendritic cell neoplasms. Although TRK fusions occurred in only 0.1% of patients (8 of 7,311 patients), they conferred responsiveness to TRK inhibition in vitro and in vivo in a patient-derived xenograft and a corresponding AML patient with ETV6-NTRK2 fusion. These data identify that despite their individual rarity, collectively, TRK fusions are present in a wide variety of hematologic malignancies and predict clinically significant therapeutic responses to TRK inhibition.

Background Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an extremely rare hematologic malignancy affecting 1.5-2.0 per million adults per year worldwide, which corresponds to approximately 1,000 cases in Europe. It is a highly aggressive disease characterized by skin and bone marrow involvement, with secondary sites including lymph nodes and viscera. BPDCN is associated with a poor prognosis, median overall survival of 8-14 months, and has no firm consensus for therapy. Tagraxofusp (TAG, SL-401) is currently the only approved first-line treatment for adult patients with BPDCN in Europe. TAG is a targeted therapy directed to CD123 that has shown efficacy in a controlled, prospective trial with prespecified endpoints. Specifically, TAG is a recombinant cytotoxin composed of human interleukin-3 fused to a truncated diphtheria toxin payload that targets CD123, the α-subunit of interleukin-3 receptor commonly overexpressed on the surface of BPDCN tumor cells. In the past, most adult and pediatric patients in Europe were treated with a plethora of experimental combination chemotherapies often imported from aggressive myeloid and lymphoid malignancy treatment regimens, followed by hematopoietic stem cell transplantation (SCT), as best available treatment. However, there is no robust evidence of the effectiveness and safety of these therapies for BPDCN, due to its rarity, the absence of prospective studies, and the variability in diagnostic criteria, definition of endpoints, and assessment of outcomes. As of July 2021, 65 patients with BPDCN have been treated with TAG in a clinical setting outside the US, as part of an expanded access program. Continued collection of clinical data from the use of TAG in a real-world setting in patients with BPDCN is important to increase the knowledge of clinical outcomes, especially in patient populations commonly underrepresented in clinical trials. This is the first real-world evidence prospective registry in patients with BPDCN receiving TAG. The study is designed to meet the requirements included in the marketing authorization by the European Commission, to further investigate the effectiveness and safety of TAG in the treatment of patients with first-line or relapsed/refractory BPDCN. Study Design and Methods This is a noninterventional, single-arm study (EudraCT: 2021-001684-24) in patients with BPDCN to assess clinical effectiveness and safety of TAG under real-world routine clinical practice conditions (12 mcg/kg intravenously [IV] once daily on days 1-5 of a 21-day cycle, per the summary of product characteristics general recommendation). Up to 125 patients are planned for inclusion in approximately 65 clinical sites in Europe estimated over 3 years. Eligible patients have a diagnosis of BPDCN and are scheduled to start TAG monotherapy, per physician's decision. The primary study objectives are to determine the complete response (CR) rate, defined as CR + clinical CR (CR with residual skin abnormality not indicative of active disease) after 3 months of treatment, and to assess the safety of TAG, in particular the incidence and severity of capillary leak syndrome (CLS). Secondary objectives include analysis of the rate of patients bridging to SCT, progression-free survival, overall survival, best overall response, duration of response, dose interruptions/administration of IV albumin supplementation in patients with CLS or CLS symptoms, incidence and severity of adverse events of special interest (AESIs), overall safety, and TAG treatment administered. AESIs include CLS and hepatic, renal, and cardiac events. Per routine clinical practice, quarterly data collection is anticipated during the study. In addition, data will be collected at screening, enrollment, early discontinuation, and study end (Figure). The end of the registry safety data collection will be 18 months after the last enrolled patient's first visit (LPFV). Interim analyses will be performed annually, and an effectiveness interim analysis is scheduled at 12 months post-LPFV. All effectiveness and safety analyses will be performed using descriptive statistics. Survival data will be summarized using the Kaplan-Meier method. Subgroup analyses for effectiveness and safety may be performed, on the basis of gender, age, or Eastern Cooperative Oncology Group performance status at baseline. Enrollment is planned to start by December 2021. Figure 1 Figure 1. Disclosures Platzbecker: Celgene/BMS: Honoraria; Novartis: Honoraria; Janssen: Honoraria; Takeda: Honoraria; AbbVie: Honoraria; Geron: Honoraria. Angelucci: Menarini-Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: steering commitee, Speakers Bureau; Vertex Pharmaceuticals: Honoraria, Other: DMC; Celgene BSM: Honoraria, Other: DMC; Blue Bird Bio: 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, Speakers Bureau; Crispr therapeutics: Honoraria, Other: DMC; Glaxo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Montesinos: Glycomimetics: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Tolero Pharmaceutical: Consultancy; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau; Stemline/Menarini: Consultancy. Lemoni: AbbVie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding. Spyridonidis: Menarini: Current Employment. Casariego: Menarini: Current Employment. Mughal: Stemline: Current Employment, Current holder of stock options in a privately-held company; Oxford University Press, Informa: Other: financial benefit and/or patents . 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.

Background: CD123 is a subunit of the interleukin 3 (IL3) receptor and is expressed on the surface of blasts in most cases of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). CD123 expression is often higher on leukemia cells than normal progenitors and may be enriched in residual cells surviving chemotherapy. Uniformly high CD123 is characteristic of blastic plasmacytoid dendritic cell neoplasm (BPDCN), an uncommon leukemia related to AML. Tagraxofusp (TAG, SL-401) is a recombinant protein drug consisting of IL3 fused to a truncated diphtheria toxin payload that targets CD123. Single agent TAG is approved for treatment of BPDCN. In preclinical models and in patients who received TAG, we previously found that TAG resistance in AML and BPDCN was mediated by DNA methylation and downregulation of diphthamide genes (e.g. DPH1) and subsequent resistance to diphtheria toxin (Togami, JCI 2019). TAG resistance was reversible by the hypomethylating agent azacitidine (AZA), and TAG plus AZA was more effective than either alone in xenograft models. Therefore, we performed a phase 1b trial combining TAG with AZA or with AZA and venetoclax (VEN) in patients with AML, MDS, or BPDCN. Methods: Detection of CD123 on blasts by flow or IHC was required. Eligibility included albumin ≥3.2 g/dL, normal cardiac ejection fraction, and hospitalization in cycle 1 to mitigate risks of capillary leak syndrome (CLS). The study followed a 3+3 dose escalation, plus expansion cohorts, of 28-day cycles of TAG with fixed doses of AZA or AZA-VEN. First, we tested 5 schedules of the doublet TAG (5 or 7 μg/kg/d1-5, or 7, 9, or 12 μg/kg/d1-3) with standard doses of AZA (75 mg/m2 d1-7) in newly diagnosed AML (1L), relapsed/refractory AML (R/R), or MDS with ≥10% blasts. Next, we tested 3 doses of the triplet TAG (7, 9, or 12 μg/kg/d4-6) with AZA (75 mg/m2 d1-7) and VEN (400 mg d1-21, ramp up d1-3 in cycle 1) in 1L AML, R/R AML, or R/R BPDCN. Results: 34 patients have been enrolled and 33 are evaluable (one withdrew prior to therapy). The age range is 21-86 (median 67). Median follow up is 8.4 months [95% CI, 7.1-19.1]. 18 received TAG-AZA (5 1L AML, 9 R/R AML, 4 MDS); 15 received TAG-AZA-VEN (9 1L AML, 3 R/R AML, 3 R/R BPDCN). An MTD was not reached, and the recommended phase 2 dose of TAG was determined to be 12 μg/kg/d x3d in each combination. Adverse events (AEs) were as expected for TAG or AZA+/-VEN. Grade 3+ AEs in >10% included neutropenia (30%), thrombocytopenia (27%), anemia (18%), febrile neutropenia (18%), ALT increase (12%), and bilirubin increase (12%). Eleven of 33 (33%) experienced CLS: 8 (24%) were grade 2, 2 grade 3 (6%), and 1 grade 4 (3%). One treatment-related death occurred in a 79 year-old with AML receiving TAG-AZA-VEN who experienced tumor lysis syndrome followed by CLS and multiorgan system failure during cycle 1. Eight of 9 patients (89%) with previously untreated AML (ages 59-81, median 74; 7 of 9 ELN adverse risk) who received TAG-AZA-VEN achieved best response of complete response (CR, n=5) or complete response with incomplete count recovery (CRi, n=3), at TAG doses of 7 (n=2), 9 (n=1), or 12 μg/kg/d x3d (n=6). The 8 with CR/CRi included two AMLs with TP53 mutation and adverse karyotype, and three with secondary AML, two which had concomitant mature pDC expansion, a.k.a. "pDC-AML" (Xiao, Blood 2021). At the time of data cut off, 4 of 8 have gone to allogeneic stem cell transplantation (alloSCT) and 3 remain on therapy. Three patients with relapsed/refractory BPDCN (all had prior single agent TAG) received TAG-AZA-VEN and 2 of 3 responded (CRc=1, CRi=1), who both went to alloSCT. Four patients with previously untreated MDS and ≥10% blasts received TAG-AZA. 3 of 4 responded (all 3 with TP53 mutation) with CR (n=2) and marrow CR (n=1), and two went to alloSCT. Among 14 patients with 1L (5) or R/R (9) AML on TAG-AZA, and 3 with R/R AML on TAG-AZA-VEN, one with 1L AML (17p- and complex karyotype) achieved a CRi on TAG-AZA. Responses in all groups included patients with high and low CD123 by central flow. Conclusions: Combining TAG with AZA or AZA-VEN is feasible, with expected TAG or AZA+/-VEN toxicities. CLS is an important consideration for TAG, requiring monitoring and early implementation of supportive care. The activity of TAG-AZA-VEN in previously untreated AML and R/R BPDCN, and of TAG-AZA in MDS are encouraging, including in high-risk AML/MDS subtypes such as TP53 mutated. These data support continued development of TAG combinations in CD123+ malignancies. Figure 1 Figure 1. Disclosures Lane: Qiagen: Consultancy, Honoraria; N-of-One: Consultancy, Honoraria; Stemline Therapeutics: Research Funding; AbbVie: Research Funding. Stein: Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau; Stemline: Speakers Bureau. Garcia: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Research Funding; AstraZeneca: Research Funding; Genentech: Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Prelude: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Stone: AbbVie: Consultancy; Syros: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Astellas: Membership on an entity's Board of Directors or advisory committees; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Foghorn Therapeutics: Consultancy; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Onconova: Consultancy; Syndax: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy, Research Funding; Gemoab: Membership on an entity's Board of Directors or advisory committees; Actinium: Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy; GlaxoSmithKline: Consultancy; Janssen: Consultancy; Jazz: Consultancy; Novartis: Consultancy, Research Funding; Aprea: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Consultancy. Winer: Novartis: Consultancy; Takeda: Consultancy; Abbvie: Consultancy. Mughal: Oxford University Press, Informa: Other: financial benefit and/or patents ; Stemline: Current Employment, Current holder of stock options in a privately-held company. Brooks: Stemline Therapeutics: Current Employment. Konopleva: KisoJi: Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Rafael Pharmaceuticals: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Ascentage: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding; Agios: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Ablynx: Other: grant support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Cellectis: Other: grant support; Calithera: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Forty Seven: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. Pemmaraju: DAVA Oncology: Consultancy; Springer Science + Business Media: Other; Samus: Other, Research Funding; MustangBio: Consultancy, Other; Incyte: Consultancy; Clearview Healthcare Partners: Consultancy; LFB Biotechnologies: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Blueprint Medicines: Consultancy; Roche Diagnostics: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Plexxicon: Other, Research Funding; Celgene Corporation: Consultancy; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Affymetrix: Consultancy, Research Funding; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Protagonist Therapeutics, Inc.: Consultancy; Sager Strong Foundation: Other; Daiichi Sankyo, Inc.: Other, Research Funding; Cellectis S.A. ADR: Other, Research Funding; Aptitude Health: Consultancy; CareDx, Inc.: Consultancy; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy.

Introduction CMML is a clonal hematopoietic stem cell disorder with overlapping features of myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). Current therapeutic options for patients (pts) with CMML are limited, leaving a significant unmet medical need. Pts classified to have the MPN subtype, compared with the MDS subtype, and those with high-risk genetic features tend to have a higher rate of transformation to acute myeloid leukemia (AML) and median survival of 2-3 years. The seminal observation of increased expression of CD123 (interleukin-3Rα) on leukemia stem cells and clonal plasmacytoid dendritic cells led to the clinical investigation of a novel CD123-targeted agent, tagraxofusp (TAG, SL-401), in CD123-positive hematologic malignancies, including blastic plasmacytoid dendritic cell neoplasm (BPDCN), CMML, AML, and myelofibrosis. TAG demonstrated robust clinical activity in pts with BPDCN and is now approved in the US and EU for this indication. Data from an ongoing phase 1/2 study of TAG monotherapy for pts with relapsed/refractory (R/R) CMML (NCT02268253) also demonstrated clinical activity (Patnaik et al. J Clin Oncol 2019;37: abstr 7059). Herein, we present updated safety and efficacy results of this study in first-line (1L) high-risk and R/R pts. Methods A multicenter, multistage, phase 1/2 trial was designed initially to assess the safety and efficacy of TAG monotherapy in adult pts with R/R CMML (Stages 1 and 2), and subsequently expanded to include 1L high-risk and R/R pts (Stage 3A). Clinical responses were initially assessed by the International Working Group/MDS 2006 criteria, and subsequently amended to the MDS/MPN 2015 criteria. Splenomegaly was assessed by palpation in Stages 1 and 2, and by palpation and imaging in Stage 3A. TAG was administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days (d)1-3 every 21 d (cycles [C]1-4), 28 d (C5-7), and 42 d (C8 and beyond) in Stage 1, and at 12 mcg/kg (recommended phase 2 dose defined in Stage 1) every 21 d (C1-4) and 28 d (C5 and beyond) in Stages 2-3A. Results As of July 2021, 36 pts have been enrolled, comprising 20 pts with CMML-1 and 16 with CMML-2; median age is 69 years (range 42-81); 75% are male. Twenty-three (64%) pts had either high- or intermediate-risk genetics based on CPSS, GFM, MMM, or ELN risk-stratification systems. Prior therapies included HMA in 16 (43%) pts, allogeneic stem cell transplantation (allo-SCT) in 3 (8%), and other in 12 (32%); 7 (19%) pts were high-risk and treatment naive. Overall, 16 (44%) pts had baseline palpable splenomegaly, of whom 12 pts' spleen size was ≥5 cm below left costal margin. The most common (in ≥20% of pts, n=34) treatment-related adverse events (TRAEs) were hypoalbuminemia (26%), thrombocytopenia (24%), nausea (24%), and capillary leak syndrome (CLS, 21%; grade 2, n=4; grade 3, n=3). Grade ≥3 TRAEs were thrombocytopenia (21%), CLS (9%), anemia (9%), and nausea (3%). Discontinuation rate due to TRAEs was low (n=1). Overall, 4 of 36 (11%) pts achieved bone marrow morphologic complete responses (BMCRs), of whom 1 pt was bridged to allo-SCT; all 4 pts had splenomegaly at baseline. Noteworthy, 2 of the 4 BMCRs were observed in pts with high-risk genetic features. Fifteen (42%) pts with baseline splenomegaly had spleen responses; 9 (60%) pts had a ≥50% reduction in spleen size, including 5 (42%) with splenomegaly ≥5 cm at baseline. Median follow-up was 11 weeks (range 1-163 weeks). In the Stage 3A cohort, 2 high-risk 1L pts had BM partial remissions, with 1 also having clinical benefit. Three pts had a spleen volume reduction by MRI scans following C1 (range 7%-36%) and 1 pt had a reduction of 57% after C4. While on study, none of the 7 pts (2 transfusion dependent at baseline) have required blood or platelet transfusions. Updated results on Stage 3A, including total symptom scores, will be presented. Conclusions Ongoing results in pts with CMML demonstrate TAG monotherapy has significant clinical activity in 1L pts with high-risk disease as well as those with R/R disease. The responses were particularly notable in those with baseline splenomegaly. As Stage 3A of the trial continues, mutational correlates and BM PDCs are being assessed. TAG treatment is well-tolerated, with a manageable and predictable safety profile. Overall, the data suggest that TAG may offer a novel targeted approach for pts with CMML. Stage 3A of the trial continues. Disclosures Patnaik: Kura Oncology: Research Funding; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees. Ali: BMS: Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees. Wang: Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Advisory Board; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; DAVA Oncology: Consultancy, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Advisory board; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Rafael Pharmaceuticals: Other: Data safety monitoring committee; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Yacoub: Incyte: Consultancy, Honoraria, Speakers Bureau; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; ACCELERON PHARMA: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Dynavex: Current equity holder in publicly-traded company; Cara: Current equity holder in publicly-traded company; Ardelyx: Current equity holder in publicly-traded company; Seattle Genetics: Honoraria, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hylapharm: Current equity holder in publicly-traded company. Gupta: Pfizer: Consultancy; BMS-Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria; Incyte: Honoraria, Research Funding; Sierra Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Constellation Pharma: Consultancy, Honoraria; Roche: Consultancy. Lee: AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Schiller: Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; FujiFilm: Research Funding; PrECOG: Research Funding; Karyopharm: Research Funding; Actinium Pharmaceuticals, Inc: Research Funding; Sangamo: Research Funding; Tolero: Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Geron: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Takeda: Research Funding; Constellation Pharmaceuticals: Research Funding; Trovagene: Research Funding; Actuate: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Regimmune: Research Funding; Delta-Fly: Research Funding; Genentech-Roche: Research Funding; Gamida Cell Ltd.: Research Funding; Astellas: Honoraria, Research Funding, Speakers Bureau; Celator: Research Funding; Daiichi-Sankyo: Research Funding; Arog: Research Funding; Forma: Research Funding; Samus: Research Funding; Deciphera: Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; Elevate: Research Funding; Bio: Research Funding; Ono-UK: Consultancy, Research Funding; Abbvie: Research Funding; Mateon: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Onconova: Research Funding; Novartis: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Pharma: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Biomed Valley Discoveries: Research Funding; Eli Lilly: Research Funding; ASH foundation: Other: Chair-unpaid; Sellas: Research Funding; Ono: Consultancy; Incyte: Consultancy; Ariad: Research Funding; AstraZeneca: Consultancy; Kaiser Permanente: Consultancy; Cyclacel: Research Funding; MedImmune: Research Funding; Ambit: Research Funding; Leukemia & Lymphoma Society: Research Funding; Bluebird Bio: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Foran: takeda: Research Funding; taiho: Honoraria; syros: Honoraria; boehringer ingelheim: Research Funding; trillium: Research Funding; abbvie: Research Funding; aptose: Research Funding; actinium: Research Funding; kura: Research Funding; sanofi aventis: Honoraria; gamida: Honoraria; certara: Honoraria; servier: Honoraria; revolution medicine: Honoraria; bms: Honoraria; pfizer: Honoraria; novartis: Honoraria; OncLive: Honoraria; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Brooks: Stemline Therapeutics: Current Employment. Mughal: Oxford University Press, Informa: Other: financial benefit and/or patents ; Stemline: Current Employment, Current holder of stock options in a privately-held company. Pemmaraju: Cellectis S.A. ADR: Other, Research Funding; Daiichi Sankyo, Inc.: Other, Research Funding; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; CareDx, Inc.: Consultancy; Aptitude Health: Consultancy; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Springer Science + Business Media: Other; Bristol-Myers Squibb Co.: Consultancy; Sager Strong Foundation: Other; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; ImmunoGen, Inc: Consultancy; Samus: Other, Research Funding; Plexxicon: Other, Research Funding; Blueprint Medicines: Consultancy; Clearview Healthcare Partners: Consultancy; DAVA Oncology: Consultancy; Roche Diagnostics: Consultancy; MustangBio: Consultancy, Other; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Celgene Corporation: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; LFB Biotechnologies: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Incyte: Consultancy; Affymetrix: Consultancy, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Pacylex Pharmaceuticals: Consultancy.

Introduction: The interleukin-3 receptor alpha chain (CD123) is a cell-surface target aberrantly expressed on various myeloid neoplasms including blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML), and myelofibrosis (MF). Tagraxofusp (TAG, SL-401), a first-in-class CD123-targeted therapy, is the only treatment approved by the FDA and EMA for patients (pts) with BPDCN. It has also been investigated in phase 1/2 clinical trials for AML (including pts with minimal residual disease [MRD]), CMML, and MF. We report the aggregated safety data of TAG monotherapy from trials in BPDCN, AML, CMML, and MF. Methods: An integrated safety analysis was performed for pts who received TAG monotherapy in three phase 1/2, multicenter clinical studies: Study 0114 (NCT02113982; BPDCN/AML), Study 0214 (NCT02270463; AML with/without MRD), and Study 0314 (NCT02268253; CMML/MF; Table 1). Pts received the recommended phase 2 dose of 12 mcg/kg/day (d) IV on d1-3 (MF and CMML) or d1-5 (BPDCN and AML) and were analyzed for incidence and timing of treatment-related adverse events (TRAEs), AEs of interest, and discontinuations. Safety data for TAG monotherapy, reported as individual case study reports (ICSRs) postapproval (US) and from an early access program (EAP; EU) are also presented. Results: In total, 201 pts receiving TAG (12 mcg/kg/d) in a clinical trial setting were included: BPDCN, n=86; AML, n=36; AML with/without MRD, n=10; CMML, n=33; MF, n=36. As of Jul 2021, 11 (6%) pts discontinued TAG due to any-grade (Gr) TRAE. Most common TRAEs (any-Gr) are shown in Table 2 and included hypoalbuminemia (41%), increased alanine aminotransferase (ALT; 40%), increased aspartate aminotransferase (AST; 39%), and thrombocytopenia (26%). The most common Gr ≥3 TRAEs were thrombocytopenia (n=41; 20%), increased AST (n=40; 20%), and increased ALT (n=35; 17%). Tumor lysis syndrome occurred in 5% of pts and 1.5% had infusion-related reactions. Any-Gr and Gr ≥3 hematologic TRAEs are presented in Table 3. Most common was thrombocytopenia. All TRAEs were transient in nature; prolonged bone marrow suppression was not observed. Overall, 23% (47/201) of pts experienced ≥1 treatment-related serious AE. Onset of most TRAEs, irrespective of Gr, commonly occurred in cycle 1 and resolved by cycle 2. Although the number of pts in cycles ≥2 was lower than in cycle 1, the incidence rates of common TRAEs also substantially decreased in subsequent cycles. Capillary leak syndrome (CLS) occurred in 17% of the overall 201 pts. The majority of all CLS events were nonsevere, Gr ≤2 (n=22; 63%); also reported were Gr 3, n=10 (29%); Gr 4, n=3 (9%), and 2 pts experienced a Gr 5 event. Onset of CLS was usually within the first week of cycle 1 (median time to onset [range], d: 5.5 [1-51]) and resolved quickly (median time to resolution [range], d: 5.0 [2-69]); no pts experienced the first onset after cycle 2. Of the 15 pts who resumed treatment after an initial CLS event, only 1 pt experienced a recurrence. The most common AEs reported as ICSRs postapproval and from an EAP (December 2018 to June 2021) were CLS, blood albumin decreased, thrombocytopenia, pyrexia, and hepatic enzyme increased. No new safety signals that would alter the safety profile were observed. Conclusions: This integrated analysis represents the largest collection of safety data (N=201) following treatment with TAG monotherapy. TAG has an established and manageable safety profile, with the vast majority of AEs reported as transient and decreasing in frequency/severity with increasing cycles. CLS was reported in 17% of pts; onset was usually within cycle 1, resolved quickly (median time to resolution: 5.0 d) by early intervention measures including holding treatment, and no pts experienced first onset after cycle 2. Risk-minimization guidelines for CLS were developed and implemented during clinical trials and incorporated into prescribing information. No myelosuppression or cumulative toxicity was observed over multiple treatment cycles. The safety profile observed postapproval and in the EAP was consistent with the clinical trial data reported, reflecting successful adoption of risk-management strategies in real-world practice. These data confirm the favorable benefit-risk profile of TAG monotherapy has been maintained in the 3 years following US approval. Figure 1 Figure 1. Disclosures Pemmaraju: ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Blueprint Medicines: Consultancy; Incyte: Consultancy; Bristol-Myers Squibb Co.: Consultancy; Pacylex Pharmaceuticals: Consultancy; Cellectis S.A. ADR: Other, Research Funding; Aptitude Health: Consultancy; Celgene Corporation: Consultancy; CareDx, Inc.: Consultancy; Springer Science + Business Media: Other; Daiichi Sankyo, Inc.: Other, Research Funding; Samus: Other, Research Funding; Clearview Healthcare Partners: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; MustangBio: Consultancy, Other; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; LFB Biotechnologies: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Affymetrix: Consultancy, Research Funding; DAVA Oncology: Consultancy; Plexxicon: Other, Research Funding; Roche Diagnostics: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ImmunoGen, Inc: Consultancy. Kantarjian: NOVA Research: Honoraria; Aptitude Health: Honoraria; Immunogen: Research Funding; BMS: Research Funding; Precision Biosciences: Honoraria; Novartis: Honoraria, Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Astra Zeneca: Honoraria; Astellas Health: Honoraria; Jazz: Research Funding; Ipsen Pharmaceuticals: Honoraria; Amgen: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; KAHR Medical Ltd: Honoraria; AbbVie: Honoraria, Research Funding; Taiho Pharmaceutical Canada: Honoraria. Sweet: Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AROG: 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. Wang: Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; DAVA Oncology: Consultancy, Speakers Bureau; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Takeda: Consultancy, Honoraria, Other: Advisory board; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Rafael Pharmaceuticals: Other: Data safety monitoring committee; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Lane: N-of-One: Consultancy, Honoraria; Stemline Therapeutics: Research Funding; Qiagen: Consultancy, Honoraria; AbbVie: Research Funding. Ali: Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees. Stein: Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau; Stemline: Speakers Bureau. Yacoub: Agios: Membership on an entity's Board of Directors or advisory committees; Acceleron Pharma: Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau. Rizzieri: Celltron/Teva: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: presentation to FDA for biosimilar review ; AROG: Other; Amgen: Other: personal fee; Bayer: Consultancy, Honoraria; Kite: Other: personal fee; Mustang: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Other: personal fee; Gilead: Other: personal fee; Jazz: Other: personal fee; Pharmacyclics: Other. Vasu: Seattle Genetics: Other: travel support; Boehringer Ingelheim: Other: Travel support; Kiadis, Inc.: Research Funding; Omeros, Inc.: Membership on an entity's Board of Directors or advisory committees. Gupta: AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy; Constellation Pharma: Consultancy, Honoraria; Pfizer: Consultancy; BMS-Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Research Funding. Lee: BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Schiller: Sangamo: Research Funding; Actinium Pharmaceuticals, Inc: Research Funding; FujiFilm: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Abbvie: Research Funding; Karyopharm: Research Funding; Onconova: Research Funding; Celator: Research Funding; Actuate: Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Trovagene: Research Funding; Deciphera: Research Funding; Gamida Cell Ltd.: Research Funding; Forma: Research Funding; Ono-UK: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Arog: Research Funding; Takeda: Research Funding; Geron: Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; PrECOG: Research Funding; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Mateon: Research Funding; Constellation Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; Tolero: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Samus: Research Funding; Astellas: Honoraria, Research Funding, Speakers Bureau; Regimmune: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Bio: Research Funding; Elevate: Research Funding; Delta-Fly: Research Funding; Genentech-Roche: Research Funding; Ariad: Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Pharma: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Biomed Valley Discoveries: Research Funding; Eli Lilly: Research Funding; ASH foundation: Other: Chair-unpaid; Sellas: Research Funding; Ono: Consultancy; Incyte: Consultancy; AstraZeneca: Consultancy; Kaiser Permanente: Consultancy; Cyclacel: Research Funding; MedImmune: Research Funding; Ambit: Research Funding; Leukemia & Lymphoma Society: Research Funding; Bluebird Bio: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Foran: trillium: Research Funding; actinium: Research Funding; aptose: Research Funding; novartis: Honoraria; OncLive: Honoraria; servier: Honoraria; gamida: Honoraria; takeda: Research Funding; boehringer ingelheim: Research Funding; abbvie: Research Funding; certara: Honoraria; bms: Honoraria; pfizer: Honoraria; sanofi aventis: Honoraria; revolution medicine: Honoraria; taiho: Honoraria; syros: Honoraria; kura: Research Funding; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Walter: Macrogenics: Consultancy, Research Funding; Jazz: Research Funding; Pfizer: Consultancy, Research Funding; Selvita: Research Funding; Amphivena: Consultancy, Other: ownership interests; Agios: Consultancy; Astellas: Consultancy; BMS: Consultancy; Genentech: Consultancy; Janssen: Consultancy; Kite: Consultancy; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding. Sieminski: Stemline Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Patnaik: Kura Oncology: Research Funding; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mughal: Oxford University Press, Informa: Other: financial benefit and/or patents ; Stemline: Current Employment, Current holder of stock options in a privately-held company. Konopleva: Calithera: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Stemline Therapeutics: Research Funding; KisoJi: Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Cellectis: Other: grant support; Sanofi: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding.

Introduction: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare myeloid malignancy characterized by plasmacytoid dendritic cells that aberrantly express interleukin-3 receptor alpha (CD123). It is highly aggressive, associated with a poor prognosis, and the median age at diagnosis is 60-70 years (yr). Clinical presentation is marked by skin and bone marrow involvement; secondary sites include peripheral blood, lymph nodes, and viscera. Tagraxofusp (TAG, SL-401), a first-in-class CD123-targeted therapy, is the only FDA- and EMA-approved treatment for BPDCN. The pivotal trial (NCT02113982) demonstrated that treatment with TAG 12 mcg/kg resulted in a complete response (CR) or clinical CR (CRc; CR with residual skin abnormality not indicative of active disease) in 57% of patient (pts), an overall response rate (ORR) of 75%, and a duration of response (DOR) of 24.9 months (mo) in first-line (1L) pts. Safety profile is well characterized and manageable in 1L and relapsed/refractory (R/R) pts with BPDCN. We report a sub-analysis of this trial stratifying 1L pts by age and baseline site of disease involvement (skin-only, systemic-only, and skin + systemic). Methods: We conducted a multicenter, 4-stage, single-arm phase 1/2 trial enrolling 1L (n=69) and R/R (n=20) pts with BPDCN. Pts received TAG IV infusions once daily on days 1-5 of a 21-day cycle. In Stage 1 (dose escalation), TAG was dosed at 7 or 12 mcg/kg; in Stages 2 (expansion), 3 (pivotal, confirmatory), and 4 (continued access), TAG was dosed at 12 mcg/kg. Main outcome measures were CR (defined as CR + CRc), ORR, overall survival, and safety. Results: In total, 65 1L pts received TAG at 12 mcg/kg. Most were male, reflective of real-world pts. Age and efficacy outcomes by age and baseline disease involvement are presented in the Table. Similar rates of CR/CRc and ORR were seen across the age cohorts and across the cohorts stratified by baseline disease involvement. In 1L BPDCN pts ≥75 yr (n=11), CR/CRc and ORRs were 55% and 82%, respectively, and similar to pts 6 mo, including 2 pts with DOR of 23 and 52 mo); the probability of survival at 12 and 24 mo was 42% and 24%, respectively. Most common treatment-emergent adverse events (TEAEs) across all age cohorts were increased alanine aminotransferase (ALT; 50% were pyrexia, thrombocytopenia, hypoalbuminemia, and fatigue. In pts stratified by baseline disease involvement, the most common TEAEs were ALT and pyrexia (53% each) in the skin-only group; increased ALT, increased AST, fatigue, and nausea (75% each) in the systemic-only group; increased ALT (71%) and increased AST (64%) in the skin + systemic group. In total, 13 pts experienced capillary leak syndrome (CLS; grade [gr] 3, n=3; gr 4, n= 1; gr 5, n=2 ; the highest incidence of CLS occurred in pts aged ≥65 to Conclusions: TAG as a first-line treatment for BPDCN was efficacious across all age cohorts including older pts and pts with significant baseline disease. High rates of durable CRs enabled over half of the pts in CR to be bridged to HSCT, including older adults and pts with extensive baseline disease. Some pts who were not transplanted and maintained on TAG had meaningful relapse-free survival - up to 4 yr in one case. Safety events were manageable, transient, mainly occurring in cycle 1, and similar for older pts vs younger pts. Baseline disease involvement did not appear to predispose pts to different TEAEs. Figure 1 Figure 1. Disclosures Pemmaraju: ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Bristol-Myers Squibb Co.: Consultancy; LFB Biotechnologies: Consultancy; Aptitude Health: Consultancy; CareDx, Inc.: Consultancy; Affymetrix: Consultancy, Research Funding; Blueprint Medicines: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Clearview Healthcare Partners: Consultancy; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Roche Diagnostics: Consultancy; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo, Inc.: Other, Research Funding; Plexxicon: Other, Research Funding; Cellectis S.A. ADR: Other, Research Funding; MustangBio: Consultancy, Other; DAVA Oncology: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Springer Science + Business Media: Other; Protagonist Therapeutics, Inc.: Consultancy; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Incyte: Consultancy; Celgene Corporation: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy; Samus: Other, Research Funding. Konopleva: AstraZeneca: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Cellectis: Other: grant support; Forty Seven: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Agios: Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Ascentage: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Rafael Pharmaceuticals: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding; KisoJi: Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. Sweet: AROG: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, 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. Stein: Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau; Stemline: Speakers Bureau. Vasu: Seattle Genetics: Other: travel support; Boehringer Ingelheim: Other: Travel support; Kiadis, Inc.: Research Funding; Omeros, Inc.: Membership on an entity's Board of Directors or advisory committees. Rizzieri: Celltron/Teva: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: presentation to FDA for biosimilar review ; Mustang: Consultancy, Honoraria; Bayer: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Jazz: Other: personal fee; Gilead: Other: personal fee; Incyte: Other: personal fee; Amgen: Other: personal fee; Kite: Other: personal fee; AROG: Other; Pharmacyclics: Other. Wang: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Rafael Pharmaceuticals: Other: Data safety monitoring committee; DAVA Oncology: Consultancy, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Advisory board; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Genentech: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Kantarjian: Ipsen Pharmaceuticals: Honoraria; AbbVie: Honoraria, Research Funding; Jazz: Research Funding; Astellas Health: Honoraria; Pfizer: Honoraria, Research Funding; Aptitude Health: Honoraria; Precision Biosciences: Honoraria; Astra Zeneca: Honoraria; Taiho Pharmaceutical Canada: Honoraria; KAHR Medical Ltd: Honoraria; NOVA Research: Honoraria; Daiichi-Sankyo: Research Funding; Amgen: Honoraria, Research Funding; Ascentage: Research Funding; BMS: Research Funding; Novartis: Honoraria, Research Funding; Immunogen: Research Funding. Brooks: Stemline Therapeutics: Current Employment. Mughal: Stemline: Current Employment, Current holder of stock options in a privately-held company; Oxford University Press, Informa: Other: financial benefit and/or patents . Lane: Qiagen: Consultancy, Honoraria; N-of-One: Consultancy, Honoraria; Stemline Therapeutics: Research Funding; AbbVie: Research Funding.

Introduction: Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) characterized by splenomegaly, constitutional symptoms, bone marrow fibrosis, and a propensity toward transformation to acute myeloid leukemia. Type I JAK inhibitors (JAKi) are the only approved therapy and can provide symptom control and reduction of splenomegaly in eligible patients. However, JAKi do not significantly impact disease progression, and many patients are not eligible due to coexisting cytopenias. Patients with MF who have relapsed and/or are refractory (R/R) to JAKi have poor survival. Therefore, novel agents, moving beyond JAKi-based treatments, are urgently needed. CD123, also known as the interleukin-3 receptor alpha chain, is expressed on maturing myeloid cells and progenitors in MF, making it an attractive therapeutic target. Tagraxofusp (TAG, SL-401) is a CD123-targeted therapy which is FDA and EMA approved for the treatment of blastic plasmacytoid dendritic cell neoplasm. A phase 1/2 study of TAG monotherapy in patients with MF who were R/R to approved JAKi (NCT02268253) was initiated. Herein, we present updated safety and efficacy data. Methods: A 2-stage multicenter, phase 1/2 study enrolled patients with R/R MF. Patients in Stage 1 (dose escalation) received 7, 9, or 12 mcg/kg/day TAG intravenously on days 1-3, every 21 days (cycles 1-4), every 28 days (cycles 5-7), and every 42 days (for cycles 8 and beyond); 12 mcg/kg/day was given every 21 days (cycles 1-4), and every 28 days (cycles 5+) in Stage 2. Enrollment in Stage 2 (expansion) was restricted to patients who met the DIPSS-plus intermediate-2 or high-risk disease criteria, those who were R/R or intolerant to JAKi therapy, and those who were not eligible for immediate stem cell transplantation. Responses were assessed on the basis of the International Working Group MPN Research and Treatment/European LeukemiaNet (IWG-MRT/ELN) criteria (Tefferi et al. Blood 2013;122:1395-1398). Results: As of July 1, 2021, 39 patients with MF were treated. Median age was 70 years (range 54-87) and 46% were female. The baseline characteristics comprised thrombocytopenia ( Conclusions: TAG monotherapy demonstrated clinical efficacy and a predictable and manageable safety profile in patients with MF characterized as high-risk, including those who are refractory to JAKi and those with associated monocytosis, thrombocytopenia, advanced disease, and high-risk genetic features. This phase 1/2 study confirms the safety and clinical efficacy of TAG administered as a monotherapy in a cohort of poor-prognosis patients with MF. Given the genomic and epigenomic complexity of MF, with the clonal heterogeneity and additional subclones, TAG is planned to be tested as part of a combination strategy in high-risk patients with MF who are either R/R, intolerant to, or who have had a prior suboptimal response to JAKi. Figure 1 Figure 1. Disclosures Yacoub: Agios: Membership on an entity's Board of Directors or advisory committees; Acceleron Pharma: Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau. Patnaik: Kura Oncology: Research Funding; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees. Ali: Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees. Wang: Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Advisory board; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; DAVA Oncology: Consultancy, Speakers Bureau; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Rafael Pharmaceuticals: Other: Data safety monitoring committee; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Gupta: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria; BMS-Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Research Funding; Roche: Consultancy; Constellation Pharma: Consultancy, Honoraria; Sierra Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy. Lee: BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Schiller: FujiFilm: Research Funding; Deciphera: Research Funding; Daiichi-Sankyo: Research Funding; Constellation Pharmaceuticals: Research Funding; Celator: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Karyopharm: Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Actinium Pharmaceuticals, Inc: Research Funding; Samus: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Geron: Research Funding; Bluebird Bio: Research Funding; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Mateon: Research Funding; Onconova: Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; PrECOG: Research Funding; Regimmune: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Genentech-Roche: Research Funding; Gamida Cell Ltd.: Research Funding; Forma: Research Funding; Delta-Fly: Research Funding; Sangamo: Research Funding; Elevate: Research Funding; Biomed Valley Discoveries: Research Funding; Bio: Research Funding; Actuate: Research Funding; Astellas: Honoraria, Research Funding, Speakers Bureau; Abbvie: Research Funding; Leukemia & Lymphoma Society: Research Funding; Ono-UK: Consultancy, Research Funding; Johnson & Johnson: Current equity holder in publicly-traded company; Arog: Research Funding; Trovagene: Research Funding; Tolero: Research Funding; Takeda: Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding; Pharma: Consultancy; Eli Lilly: Research Funding; ASH foundation: Other: Chair-unpaid; Sellas: Research Funding; Ono: Consultancy; Incyte: Consultancy; Ariad: Research Funding; AstraZeneca: Consultancy; Kaiser Permanente: Consultancy; Cyclacel: Research Funding; MedImmune: Research Funding; Ambit: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Taparia: Novartis: Consultancy. Verstovsek: Protagonist Therapeutics: Research Funding; Roche: Research Funding; AstraZeneca: Research Funding; Celgene: Consultancy, Research Funding; NS Pharma: Research Funding; PharmaEssentia: Research Funding; CTI BioPharma: Research Funding; Gilead: Research Funding; Incyte Corporation: Consultancy, Research Funding; Ital Pharma: Research Funding; Blueprint Medicines Corp: Research Funding; Promedior: Research Funding; Genentech: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy. Khoury: Stemline Therapeutics: Research Funding; Angle: Research Funding; Kiromic: Research Funding. Brooks: Stemline Therapeutics: Current Employment. Mughal: Stemline: Current Employment, Current holder of stock options in a privately-held company; Oxford University Press, Informa: Other: financial benefit and/or patents . Pemmaraju: LFB Biotechnologies: Consultancy; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Samus: Other, Research Funding; Springer Science + Business Media: Other; MustangBio: Consultancy, Other; Incyte: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; DAVA Oncology: Consultancy; Aptitude Health: Consultancy; Daiichi Sankyo, Inc.: Other, Research Funding; Affymetrix: Consultancy, Research Funding; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Roche Diagnostics: Consultancy; CareDx, Inc.: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Plexxicon: Other, Research Funding; Sager Strong Foundation: Other; Clearview Healthcare Partners: Consultancy; Blueprint Medicines: Consultancy; Cellectis S.A. ADR: Other, Research Funding; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy.

Genomic profiling of circulating tumor DNA derived from cell-free DNA (cfDNA) in blood can provide a noninvasive method for detecting genomic biomarkers to guide clinical decision making for cancer patients. We developed a hybrid capture–based next-generation sequencing assay for genomic profiling of circulating tumor DNA from blood (FoundationACT). High-sequencing coverage and molecular barcode–based error detection enabled accurate detection of genomic alterations, including short variants (base substitutions, short insertions/deletions) and genomic re-arrangements at low allele frequencies (AFs), and copy number amplifications. Analytical validation was performed on 2666 reference alterations. The assay achieved >99% overall sensitivity (95% CI, 99.1%–99.4%) for short variants at AF >0.5%, >95% sensitivity (95% CI, 94.2%–95.7%) for AF 0.25% to 0.5%, and 70% sensitivity (95% CI, 68.2%–71.5%) for AF 0.125% to 0.25%. No false positives were detected in 62 samples from healthy volunteers. Genomic alterations detected by FoundationACT demonstrated high concordance with orthogonal assays run on the same clinical cfDNA samples. In 860 routine clinical FoundationACT cases, genomic alterations were detected in cfDNA at comparable frequencies to tissue; for the subset of cases with temporally matched tissue and blood samples, 75% of genomic alterations and 83% of short variant mutations detected in tissue were also detected in cfDNA. On the basis of analytical validation results, FoundationACT has been approved for use in our Clinical Laboratory Improvement Amendments–certified/College of American Pathologists–accredited/New York State–approved laboratory.

Background We previously described a tumor-promoting and immunosuppressive role of plasmacytoid dendritic cells (pDCs; CD123/IL-3R+) in multiple myeloma (MM) pathogenesis (Chauhan et al. Cancer Cell, 2009; Ray et al, Leukemia, 2018). Tagraxofusp, an FDA-approved (for patients with blastic plasmacytoid dendritic cell neoplasm [BPDCN]) novel targeted therapy directed against CD123, can trigger anti-MM activity by decreasing the viability of MM-promoting pDCs. These observations led to a recently completed phase 1/2 clinical trial of tagraxofusp and pomalidomide/dexamethasone in relapsed/refractory MM patients (NCT02661022). The treatment regimen demonstrated preliminary safety and efficacy, with 5 of 9 heavily pretreated patients achieving durable partial response (PR) (ASH 2019). Here, we report the early results of our translational correlative studies using bone marrow (BM), peripheral blood (PB), and serum from the study cohort. Methods Tagraxofusp is a bioengineered targeted therapy directed to CD123 developed by fusing human IL-3 to a truncated diphtheria toxin (DT) payload (Stemline Therapeutics, NY). pDCs and patient MM cells were purified from BM/PB samples after informed consent, and quantified using FACS, as described (Ray et al, Leukemia, 2018). A novel high throughput seroproteomics platform SOMAscan was used to analyze 1,310 protein analytes in serum samples from MM patients (n = 9). SOMAscan data were subjected to meta-analysis to generate heatmaps, followed by hierarchical cluster analysis. SOMAscan results were validated with ELISA using supernatants from MM patient pDCs cultured with or without tagraxofusp. Results Analysis of BM/PB samples from MM patients receiving tagraxofusp therapy showed a distinct reduction in the frequency of viable pDCs [average 2% at screening vs 0.75% post-tagraxofusp; n = 6; p = 0.036]. Of note, pDCs isolated from tagraxofusp-treated patients showed decreased ability to trigger MM cell growth. SOMAscan analysis of patient serum before and after tagraxofusp therapy showed alterations in the levels of 100 proteins [Median Fold Change in expression: 0.39 to 4.5; n = 6; 3 each; p Conclusions Our correlative science studies validate the target specificity of tagraxofusp against MM pDCs in relapsed and refractory MM patients enrolled in a phase 1/2 clinical trial. Our study favors further evaluation for this novel therapeutic to improve the clinical outcome of patients with MM. Further combination studies are planned.

Background Genomic changes that occur in breast cancer during the course of disease have been informed by sequencing of primary and metastatic tumor tissue. For patients with relapsed and metastatic disease, evolution of the breast cancer genome highlights the importance of using a recent sample for genomic profiling to guide clinical decision-making. Obtaining a metastatic tissue biopsy can be challenging, and analysis of circulating tumor DNA (ctDNA) from blood may provide a minimally invasive alternative. Patients and methods Hybrid capture-based genomic profiling was carried out on ctDNA from 254 female patients with estrogen receptor-positive breast cancer. Peripheral blood samples were submitted by clinicians in the course of routine clinical care between May 2016 and March 2017. Sequencing of 62 genes was carried out to a median unique coverage depth of 7503×. Genomic alterations (GAs) in ctDNA were evaluated and compared with matched tissue samples and genomic datasets of tissue from breast cancer. Results At least 1 GA was reported in 78% of samples. Frequently altered genes were TP53 (38%), ESR1 (31%) and PIK3CA (31%). Temporally matched ctDNA and tissue samples were available for 14 patients; 89% of mutations detected in tissue were also detected in ctDNA. Diverse ESR1 GAs including mutation, rearrangement and amplification, were observed. Multiple concurrent ESR1 GAs were observed in 40% of ESR1-altered cases, suggesting polyclonal origin; ESR1 compound mutations were also observed in two cases. ESR1-altered cases harbored co-occurring GAs in PIK3CA (35%), FGFR1 (16%), ERBB2 (8%), BRCA1/2 (5%), and AKT1 (4%). Conclusions GAs relevant to relapsed/metastatic breast cancer management were identified, including diverse ESR1 GAs. Genomic profiling of ctDNA demonstrated sensitive detection of mutations found in tissue. Detection of amplifications was associated with ctDNA fraction. Genomic profiling of ctDNA may provide a complementary and possibly alternative approach to tissue-based genomic testing for patients with estrogen receptor-positive metastatic breast cancer.

// Caleb K. Stein 1 , Charlotte Pawlyn 2 , Shweta Chavan 1 , Leo Rasche 1 , Niels Weinhold 1 , Adam Corken 1 , Amy Buros 1 , Pieter Sonneveld 3 , Graham H. Jackson 4 , Ola Landgren 5 , Tariq Mughal 6, 7 , Jie He 6 , Bart Barlogie 1 , P. Leif Bergsagel 8 , Faith E. Davies 1 , Brian A. Walker 1 , Gareth J. Morgan 1 1 The Myeloma Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA 2 The Institute of Cancer Research, London, UK 3 Eramus University, Rotterdam, NL 4 Department of Haematology, Newcastle University, Newcastle-upon-Tyne, UK 5 Memorial Sloan Kettering Cancer Center, New York, New York, USA 6 FoundationOne Medicine, Cambridge, Massachusetts, USA 7 Tufts Medical Center, Boston, Massachusetts, USA 8 Mayo Clinic, Scottsdale, Arizona, USA Correspondence to: Caleb K. Stein, email: CKStein@uams.edu Keywords: multiple myeloma, gene expression profiling, mutational analysis, translocation cyclin D (TC) Received: January 13, 2017 Accepted: February 15, 2017 Published: February 24, 2017 ABSTRACT We examined a set of 805 cases that underwent DNA sequencing using the FoundationOne Heme (F1H) targeted sequencing panel and gene expression profiling. Known and likely variant calls from the mutational data were analyzed for significant associations with gene expression defined translocation cyclin D (TC) molecular subgroups. The spectrum of KRAS, NRAS, and BRAF codon mutations varied across subgroups with NRAS mutations at Q61 codon being common in hyperdiploid (HRD) and t(11;14) myeloma while being rare in MMSET and MAF. In addition, the presence of RAS-RAF mutations was inversely associated with NFκB pathway activation in all subgroups excluding MAF. In the MMSET subgroup, cases with low FGFR3 expression frequently had RAS-RAF mutations. Conditional inference tree analysis determined that mutation and homozygous deletion of TP53, CDKN2C, and RB1 were key prognostic factors associated with adverse outcome in a non-relapse clinical setting. In conclusion, this study highlights the heterogeneity in the distribution and clinical outcomes of RAS codon and other mutations in multiple myeloma dependent upon primary molecular subgroup.

Study Rationale: At present there are no effective therapies for patients with primary or secondary myelofibrosis (MF) after the failure of the JAK inhibitory class of therapies. Furthermore, patients with monocytosis, thrombocytopenia, accelerated phase, or high-risk genetic features fare poorly with JAK inhibitors (JAKi), as intolerance, resistance, and/or ineligibility often limit treatment options. Median overall survival in most studies post-JAKi demonstrate poor outcomes (14-28 months) among patients with MF. Consequently, there is a considerable need in identifying new therapeutic targets beyond JAK-STAT inhibition. One potential cancer target is CD123, aberrantly expressed on leukemia stem cells and aberrant/malignant microenvironmental plasmacytoid dendritic cells (pDC) in certain myeloid cancers including MF. Tagraxofusp (TAG), a CD123-targeted therapy FDA-approved for patients with blastic plasmacytoid dendritic cell neoplasm, a pDC-derived malignancy, has demonstrated preclinical proof-of-concept in MF. We now report the updated results of an ongoing study of TAG monotherapy in patients with relapsed/refractory MF, or who were unable to tolerate currently approved JAKi. (NCT02268253) Experimental Design: A multicenter Phase 1/2 trial with TAG administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days 1-3 every 21 days (cycle 1-4), 28 days (cycles 5-7), and 42 days (cycles 8+) in stage 1, and 12 mcg/kg every 21 days (C1-4), 28 days (C5+) in the currently ongoing stage 2. Results: Thirty-five patients (pts) with a median age 69 years (range: 54-87) have been treated thus far: 26% had baseline monocytosis and 69% had baseline thrombocytopenia, which impacts optimal dosing of JAKi, including 37% with platelets 50% spleen reduction; 12 of 26 (46%) had symptom burden reduction, including 3 pts who met the IWG-MRT criteria. There have been three deaths, all deemed to be unrelated to study drug, occurring in cycles 1, 6, 13, respectively. The median overall survival of our cohort was 31 months (range: 0.6-42 months). Conclusions: Interim results demonstrate clinical efficacy and safety of TAG monotherapy in JAKi relapse/refractory/intolerant MF patients, including those associated with recognized poor-risk biological and clinical features, such as monocytosis. Some patients have experienced clinical benefit, including reduction in splenomegaly and improvement in quality of life and enrollment continues. Disclosures Pemmaraju: Celgene: Honoraria; DAVA Oncology: Honoraria; Roche Diagnostics: Honoraria; Blueprint Medicines: Honoraria; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria; SagerStrong Foundation: Other: Grant Support; Pacylex Pharmaceuticals: Consultancy; Novartis: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Plexxikon: Research Funding; Cellectis: Research Funding; Incyte Corporation: Honoraria; Affymetrix: Other: Grant Support, Research Funding; Daiichi Sankyo: Research Funding; Samus Therapeutics: Research Funding. Gupta:Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Incyte: Honoraria, Research Funding. Ali:Incyte Corporation: Consultancy. Yacoub:Hylapharm: Current equity holder in private company; Incyte: Speakers Bureau; Agios: Honoraria, Speakers Bureau; Novartis: Speakers Bureau; Roche: Other: Support of parent study and funding of editorial support; Dynavax: Current equity holder in publicly-traded company; Ardelyx: Current equity holder in publicly-traded company; Cara Therapeutics: Current equity holder in publicly-traded company. Wang:PTC Therapeutics: Consultancy; Stemline: Speakers Bureau; Macrogenics: Consultancy; Astellas: Consultancy; Genentech: Consultancy; Pfizer: Speakers Bureau; Abbvie: Consultancy; Jazz Pharmaceuticals: Consultancy; Bristol Meyers Squibb (Celgene): Consultancy. Lee:Roche Molecular Systems: Consultancy; Jazz: Consultancy; AstraZeneca: Consultancy; Helsinn: Other: Member -DSMB; BMS: Consultancy. Schiller:Pfizer: Current equity holder in publicly-traded company, Research Funding; Regimmune: Research Funding; Samus: Research Funding; Sangamo: Research Funding; Tolero: Research Funding; Trovagene: Research Funding; Kaiser Permanente: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Jazz Pharmaceuticals: Research Funding; Geron: Research Funding; Genentech-Roche: Research Funding; Gamida: Research Funding; FujiFilm: Research Funding; Forma: Research Funding; Bristol-Myers Squibb: Current equity holder in publicly-traded company, Research Funding; DeltaFly: Research Funding; Deciphera: Research Funding; Daiichi Sankyo: Research Funding; Cyclacel: Research Funding; Constellation: Research Funding; Celator: Research Funding; Astellas Pharma: Honoraria, Research Funding; Ariad: Research Funding; Actinium: Research Funding; Abbvie: Research Funding; Stemline: Speakers Bureau; Gilead: Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Sanofi: Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Incyte: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding; Ono Pharma: Consultancy; Celgene: Research Funding, Speakers Bureau; Karyopharm: Research Funding; Kite Pharma: Research Funding; Mateon: Research Funding; MedImmune: Research Funding; Onconova: Research Funding. Brooks:Stemline: Current Employment. Rupprecht:Stemline: Current Employment. Talpaz:Takeda: Research Funding; IMAGO: Consultancy; Constellation Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Mughal:Stemline: Current Employment. Verstovsek:PharmaEssentia: Research Funding; AstraZeneca: Research Funding; ItalPharma: Research Funding; Incyte Corporation: Consultancy, Research Funding; Gilead: Research Funding; Promedior: Research Funding; CTI Biopharma Corp: Research Funding; Genentech: Research Funding; Blueprint Medicines Corp: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Research Funding; Protagonist Therapeutics: Research Funding.

Background Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, hematologic malignancy, comprised of clonal plasmacytoid dendritic cells that are CD123-positive and associated with historically poor outcomes. In 2018, tagraxofusp (TAG), a targeted therapy directed to CD123, became the first-in-class FDA approved treatment for children and adults with BPDCN ages 2 years and older. Treatment with TAG resulted in durable clinical responses with a manageable safety profile in both treatment-naive and relapsed/refractory (R/R) patients. Herein, we present long-term follow-up results ( NCT02113982 ). Objectives To assess the safety and efficacy of TAG in patients with untreated and previously treated BPDCN. Methods In this multicenter, multi-stage, single-arm trial 44 patients with treatment-naive or R/R BPDCN were treated at the indicated dose (12 mcg/kg). In Stage 1 (dose escalation) patients received TAG daily IV infusions at 7 or 12 mcg/kg on days 1–5 of a 21-day cycle. In Stage 2 (expansion) and Stage 3 (pivotal, confirmatory), TAG was dosed at 12 mcg/kg. Key efficacy measures included objective response rate (ORR), complete response (CR), clinical CR (CRc), defined as CR with residual skin abnormality not indicative of active disease, and overall survival (OS). Results Twenty-nine treatment-naive and 15 R/R BPDCN patients were treated for a median duration of 5 and 3 cycles, respectively. Most common treatment emergent adverse events (TEAEs) include hypoalbuminemia, increased transaminases, thrombocytopenia, nausea, fatigue and pyrexia. The most serious adverse event was capillary leak syndrome (CLS), 19% in all grades (one patient with Grade 4 and two with Grade 5). Incidence of TEAEs leading to TAG discontinuation was 2%; temporary dose interruptions for TEAE management were common (68%). In treatment-naive patients ORR was 90%, CR+CRc rate was 72%, and 45% were bridged to stem cell transplant. Median time to response was rapid; 65% of patients achieved complete response by C2. Median overall survival was 26 months; 24-month survival probabilities of 52%. In R/R patients, ORR was 67%, including 2 CR+CRc. Conclusions In the largest prospectively designed study conducted to date, TAG demonstrated robust and durable responses with a median OS of 26 months and a well-characterized safety profile including recognition for CLS.

Background: Most patients (pts) with intermediate- and high-risk myelofibrosis (MF) achieve spleen volume reduction and symptomatic improvement but no significant impact on the driver mutations or risk to transformation. Furthermore, patients with baseline thrombocytopenia, monocytosis, or high-risk genetic features and those in accelerated phase fare poorly. There is a need for drug development in MF to focus on identifying new therapeutic targets. A novel approach involves tagraxofusp (TAG), a CD123-targeted therapy, approved for blastic plasmacytoid dendritic cell neoplasm in 2018 and noted to have preclinical activity in MF. Herein, we present updated results from a phase I/II study on TAG monotherapy in patients with relapsed/refractory (R/R) MF. Aims: To assess safety and evaluate efficacy of TAG in patients with relapsed, refractory MF using IWG-MRT response criteria. Methods: Multicenter ongoing trial with TAG administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days 1–3 every 21 days (cycle 1–4), 28 days (cycles 5–7), and 42 days (cycles 8+) in stage 1 and 12 mcg/kg in the ongoing stage 2. Results: Thirty-two pts with a median age of 69.5 yrs have been treated: 25% had baseline monocytosis and thrombocytopenia, including 31% with platelets 50% spleen reduction; 11 of 24 (46%) had symptom burden reduction, including three pts with stringent IWG-MRT criteria; the median overall survival was 31 mos. Conclusions: The interim results demonstrate clinical efficacy and safety of TAG monotherapy in a cohort of poor-risk MF patients, including some with associated monocytosis. ( NCT02268253 )

The 60th American Society of Hematology (ASH) held in San Diego in December 2018 was followed by the 13th Post-ASH chronic myeloproliferative neoplasms (MPNs) workshop on December 4 and 5, 2018. This closed annual workshop, first introduced in 2006 by Goldman and Mughal, was organized in collaboration with Alpine Oncology Foundation and allowed experts in preclinical and clinical research in the chronic MPNs to discuss the current scenario, including relevant presentations at ASH, and address pivotal open questions that impact translational research and clinical management. This review is based on the presentations and deliberations at this workshop, and rather than provide a resume of the proceedings, we have selected some of the important translational science and treatment issues that require clarity. We discuss the experimental and observational evidence to support the intimate interaction between aging, inflammation, and clonal evolution of MPNs, the clinical impact of the unfolding mutational landscape on the emerging targets and treatment of MPNs, new methods to detect clonal heterogeneity, the challenges in managing childhood and adolescent MPN, and reflect on the treatment of systemic mastocytosis (SM) following the licensing of midostaurin.

The spectrum of somatic alterations in hematologic malignancies includes substitutions, insertions/deletions (indels), copy number alterations (CNAs), and a wide range of gene fusions; no current clinically available single assay captures the different types of alterations. We developed a novel next-generation sequencing-based assay to identify all classes of genomic alterations using archived formalin-fixed paraffin-embedded blood and bone marrow samples with high accuracy in a clinically relevant time frame, which is performed in our Clinical Laboratory Improvement Amendments-certified College of American Pathologists-accredited laboratory. Targeted capture of DNA/RNA and next-generation sequencing reliably identifies substitutions, indels, CNAs, and gene fusions, with similar accuracy to lower-throughput assays that focus on specific genes and types of genomic alterations. Profiling of 3696 samples identified recurrent somatic alterations that impact diagnosis, prognosis, and therapy selection. This comprehensive genomic profiling approach has proved effective in detecting all types of genomic alterations, including fusion transcripts, which increases the ability to identify clinically relevant genomic alterations with therapeutic relevance.

Acne vulgaris is one of the most common chronic inflammatory skin disorders among adolescents and young adults. It is associated with substantial morbidity and, rarely, with mortality. The exact worldwide incidence and prevalence are currently unknown. Current challenges involve improving understanding of the underlying pathophysiology of acne vulgaris and developing a practical treatment consensus. Expert panel discussions were held in 2013 and 2014 among a group of scientists and clinicians from the Omani and United Arab Emirate Dermatology Societies to ascertain the current optimal management of acne vulgaris, identify clinically relevant end-points and construct suitable methodology for future clinical trial designs. This article reviews the discussions of these sessions and recent literature on this topic.