Search

Familial platelet disorder (FPD) is associated with germline RUNX1mutations, establishing a preleukemic state and increasing the risk of developing leukemia. Currently, there are no intervention strategies to prevent leukemia progression. Single-cell RNA sequencing (n= 10) combined with functional analysis of samples from patients with RUNX1-FPD (n> 75) revealed that FPD hematopoietic stem and progenitor cells (HSPCs) displayed increased myeloid differentiation and suppressed megakaryopoiesis because of increased activation of prosurvival and inflammatory pathways. Bone marrow from patients with RUNX1-FPD contained an elevated cytokine milieu, exerting chronic inflammatory stress on HSPCs. RUNX1-FPD HSPCs were myeloid biased, had increased self-renewal, and were resistant to inflammation-mediated exhaustion. The bone marrow from patients with RUNX1-FPD showed high transcript and protein expression of CD74 at the preleukemic stage compared with that of healthy controls, which remained high upon patient transformation into leukemia. Further, CD74-mediated signaling was exaggerated in RUNX1-FPD HSPCs compared with healthy controls, leading to the activation of mTOR and JAK/STAT pathways with increased cytokine production. Genetic and pharmacological targeting of CD74 with ISO-1 and its downstream targets JAK1/2 and mTOR reversed RUNX1-FPD differentiation defects in vitro and in vivo and reduced inflammation. Our results highlight that inflammation is an early event in RUNX1-FPD pathogenesis, and CD74 signaling is one of the drivers of this inflammation. The repurposing of JAK1/2i (ruxolitinib) and mTORi (sirolimus) and promoting the advancement of CD74 inhibitors in clinical settings as an early intervention strategy would be beneficial to improve the phenotype of patients with RUNX1-FPD and prevent myeloid progression.

Shwachman-Diamond syndrome (SDS) is an inherited bone marrow failure syndrome with leukemia predisposition. An understanding of the hematologic complications of SDS with age could guide clinical management, but data are limited for this rare disease. We conducted a cohort study of 153 subjects from 143 families with confirmed biallelic SBDS mutations enrolled on the North American Shwachman Diamond Registry or Bone Marrow Failure Registry. The SBDS c.258 + 2T>C variant was present in all but 1 patient. To evaluate the association between blood counts and age, 2146 blood counts were analyzed for 119 subjects. Absolute neutrophil counts were positively associated with age (P < .0001). Hemoglobin was also positively associated with age up to 18 years (P < .0001), but the association was negative thereafter (P = .0079). Platelet counts and marrow cellularity were negatively associated with age (P < .0001). Marrow cellularity did not correlate with blood counts. Severe marrow failure necessitating transplant developed in 8 subjects at a median age of 1.7 years (range, 0.4-39.5), with 7 of 8 requiring transplant prior to age 8 years. Twenty-six subjects (17%) developed a myeloid malignancy (16 myelodysplasia and 10 acute myeloid leukemia) at a median age of 12.3 years (range, 0.5-45.0) and 28.4 years (range, 14.4-47.3), respectively. A lymphoid malignancy developed in 1 patient at the age of 16.9 years. Hematologic complications were the major cause of mortality (17/20 deaths; 85%). These data inform surveillance of hematologic complications in SDS.

Standardized variant curation is essential for clinical care recommendations for patients with inherited disorders. Clinical Genome Resource (ClinGen) variant curation expert panels are developing disease-associated gene specifications using the 2015 American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP) guidelines to reduce curation discrepancies. The ClinGen Myeloid Malignancy Variant Curation Expert Panel (MM-VCEP) was created collaboratively between the American Society of Hematology and ClinGen to perform gene- and disease-specific modifications for inherited myeloid malignancies. The MM-VCEP began optimizing ACMG/AMP rules for RUNX1 because many germline variants have been described in patients with familial platelet disorder with a predisposition to acute myeloid leukemia, characterized by thrombocytopenia, platelet functional/ultrastructural defects, and a predisposition to hematologic malignancies. The 28 ACMG/AMP codes were tailored for RUNX1 variants by modifying gene/disease specifications, incorporating strength adjustments of existing rules, or both. Key specifications included calculation of minor allele frequency thresholds, formulating a semi-quantitative approach to counting multiple independent variant occurrences, identifying functional domains and mutational hotspots, establishing functional assay thresholds, and characterizing phenotype-specific guidelines. Preliminary rules were tested by using a pilot set of 52 variants; among these, 50 were previously classified as benign/likely benign, pathogenic/likely pathogenic, variant of unknown significance (VUS), or conflicting interpretations (CONF) in ClinVar. The application of RUNX1-specific criteria resulted in a reduction in CONF and VUS variants by 33%, emphasizing the benefit of gene-specific criteria and sharing internal laboratory data.

Standardized variant curation is essential for clinical care recommendations for patients with inherited disorders. Clinical Genome Resource (ClinGen) variant curation expert panels are developing disease-associated gene specifications using the 2015 American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP) guidelines to reduce curation discrepancies. The ClinGen Myeloid Malignancy Variant Curation Expert Panel (MM-VCEP) was created collaboratively between the American Society of Hematology and ClinGen to perform gene- and disease-specific modifications for inherited myeloid malignancies. The MM-VCEP began optimizing ACMG/AMP rules for RUNX1because many germline variants have been described in patients with familial platelet disorder with a predisposition to acute myeloid leukemia, characterized by thrombocytopenia, platelet functional/ultrastructural defects, and a predisposition to hematologic malignancies. The 28 ACMG/AMP codes were tailored for RUNX1variants by modifying gene/disease specifications, incorporating strength adjustments of existing rules, or both. Key specifications included calculation of minor allele frequency thresholds, formulating a semi-quantitative approach to counting multiple independent variant occurrences, identifying functional domains and mutational hotspots, establishing functional assay thresholds, and characterizing phenotype-specific guidelines. Preliminary rules were tested by using a pilot set of 52 variants; among these, 50 were previously classified as benign/likely benign, pathogenic/likely pathogenic, variant of unknown significance (VUS), or conflicting interpretations (CONF) in ClinVar. The application of RUNX1-specific criteria resulted in a reduction in CONF and VUS variants by 33%, emphasizing the benefit of gene-specific criteria and sharing internal laboratory data.

Germline mutations in RUNX1result in autosomal dominant familial platelet disorder with associated myeloid malignancy (FPDMM). To characterize the hematopathologic features associated with a germline RUNX1mutation, we reviewed a total of 42 bone marrow aspirates from 14 FPDMM patients, including 24 cases with no cytogenetic clonal abnormalities, and 18 with clonal karyotypes or leukemia. We found that all aspirate smears had ≥10% atypical megakaryocytes, predominantly characterized by small forms with hypolobated and eccentric nuclei, and forms with high nuclear-to-cytoplasmic ratios. Core biopsies showed variable cellularity and variable numbers of megakaryocytes with similar features to those in the aspirates. Granulocytic and/or erythroid dysplasia (≥10% cells per lineage) were present infrequently. Megakaryocytes with separate nuclear lobes were increased in patients with myelodysplastic syndrome (MDS) and acute leukemia. Comparison to an immune thrombocytopenic purpura cohort confirms increased megakaryocytes with hypolobated eccentric nuclei in FPDMM patients. As such, patients with FPDMM often have atypical megakaryocytes with small hypolobated and eccentric nuclei even in the absence of clonal cytogenetic abnormalities; these findings are related to the underlying RUNX1germline mutation and not diagnostic of MDS. Isolated megakaryocytic dysplasia in patients with unexplained thrombocytopenia should raise the possibility of an underlying germline RUNX1mutation.

CNS directed chemotherapy (chemo) reduces the risk of CNS relapse of ALL, but the optimal way to measure baseline CNS involvement is controversial. Baseline CSF testing can provide risk stratification and often dictates CNS prophylaxis (ppx) during initial treatment. Despite advances, up to 10% of adults still suffer CNS relapse (Blood 2008;112:1646, Cancer 2014;120:3660). Testing typically focuses on conventional cytospin (CC) of CSF, but CC is limited by interobserver variability and insensitivity (Blood 2014;124:3799). Alternatively, MFC is more sensitive (ASH 2018, #658). A previous study in children with ALL found leukemia detection in the CNS by CC or MFC at diagnosis to be associated with an increased risk of both isolated bone marrow and any CNS relapse (ASH 2018, #657). To our knowledge, this use of MFC has not specifically been studied in hyperCVAD, a commonly used chemotherapy regimen for the initial treatment of adult ALL. We hypothesized that baseline lymphoblast detection in the CSF by MFC is predictive of CNS relapse.

Background:Familial platelet disorder (FPD) is caused by germline loss-of-function mutations in RUNX1an essential transcription factor regulating hematopoiesis. The absence of functional RUNX1 leads to mild-to-moderate thrombocytopenia, platelet dysfunction, and increased bleeding in FPD patients. In ~40% of cases, the patients progress to overt leukemia at median age of 33 years through unknown mechanisms. FPD patients also present with skin allergy and eczema which are associated with systematic elevation of cytokines. Given the well-established connection between inflammation and leukemia initiation and progression, we sought to investigate whether inflammatory stress play a role in regulating abnormal hematopoiesis and eventually cause clonal evolution in FPD.

Dale: Emendo BioTherapeutics: Consultancy; X4 Pharmaceuticals: Research Funding; X4 Pharmaceuticals: Honoraria. Gansner:Alnylam Pharmaceuticals: Current Employment, Current equity holder in private company. Edwards:Jazz Pharmaceuticals: Consultancy, Honoraria. Fleming:DISC Medicine: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lindsley:MedImmune: Research Funding; Takeda Pharmaceuticals: Consultancy; Bluebird Bio: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding.

Background:Shwachman-Diamond Syndrome (SDS) is a bone marrow failure disorder caused by impaired removal of EIF6 from the nascent 60S ribosome subunit, resulting in defective ribosome assembly. SDS patients have a high risk of myeloid neoplasms (MN) and the prognosis of those that develop MN is poor. Knowledge of the kinetics and functional consequences of somatic mutation acquisition in SDS may offer insight into mechanism of transformation and the potential for therapuetic intervention.

Hematopoietic stem and progenitor cells (HSPCs) acquire somatic mutations and cytogenetic abnormalities leading to myeloid neoplasms (MDS/AML). A subgroup of 10-20% MDS and AML cases undergo complex chromosomal rearrangements associated with TP53mutations and poor prognosis. One of the most common chromosomal events in high-risk myeloid neoplasms is deletion of chromosome 5q (del(5q)). In contrast to 5q- syndrome, characterized by a distal commonly deleted region (CDR) and good prognosis, the critical CDR in high-risk MDS/AML centers on 5q31. However, the key genes in the high-risk 5q-deleted region that contribute to dysregulation of hematopoiesis, chromosomal instability, and disease progression remain poorly characterized.

Background:In a prior single-institution trial, CLAG-M resulted in high rates of measurable residual disease (MRD)-negative remissions for adults with previously untreated AML or high-grade myeloid neoplasms (HG-MN) with ≥10% blasts in bone marrow and/or blood (Halpern et al.Leukemia 2018;32:2352-62). The CD33 antibody-drug conjugate, gemtuzumab ozogamicin (GO), reduces relapse and improves survival when added to other intensive chemotherapy regimens, prompting this phase 1/2 study (NCT03531918) combining GO with CLAG-M as initial therapy for fit adults with newly diagnosed AML or HG-MN.

Godwin: Pfizer: Research Funding; Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Percival: Glycomimetics: Research Funding; Cardiff Oncology: Research Funding; BMS/Celgene: Research Funding; Biosight: Research Funding; Abbvie: Research Funding; Pfizer: Research Funding; Nohla Therapeutics: Research Funding; Oscotec: Research Funding; Trillium: Research Funding. Scott: Bristol Myers Squibb: Consultancy, Honoraria, Research Funding. Halpern: Pfizer: Research Funding; Nohla Therapeutics: Research Funding; Jazz Pharmaceuticals: Research Funding; Imago Pharmaceuticals: Research Funding; Novartis: Research Funding; Bayer: Research Funding; Tolero Pharmaceuticals: Research Funding; Agios Pharmaceuticals: Research Funding; Abbvie: Consultancy; Gilead: Research Funding; Agios: Consultancy. Oehler: BMS: Consultancy; OncLive: Honoraria; Takeda: Consultancy; Pfizer: Research Funding. Orozco: Actinium Pharmaceuticals: Other: Principal Investigator, SIERRA Trial, Actinium, Research Funding. Cassaday: Pepromene Bio: Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; Kite/Gilead: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Research Funding; Vanda Pharmaceuticals: Research Funding; Servier: Research Funding; Pfizer: Consultancy, Research Funding. Walter: Pfizer: Consultancy, Research Funding; Jazz: Research Funding; Amphivena: Consultancy, Other: ownership interests; Agios: Consultancy; Selvita: Research Funding; Astellas: Consultancy; BMS: Consultancy; Genentech: Consultancy; Janssen: Consultancy; Kite: Consultancy; Macrogenics: Consultancy, Research Funding; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding.The label for cladribine does not include acute myeloid leukemia, however cladribine is frequently used to treat AML and related conditions. In this study cladribine is used in induction chemotherapy for the treated of AML and related disorders.

Becker: Glycomimetics: Research Funding; CVS Caremark: Consultancy; Abbie: Research Funding; BMS: Research Funding; Pfizer: Research Funding; Cardiff Oncology: Research Funding; SecuraBio: Research Funding.

Shwachman-Diamond Syndrome (SDS) is an inherited bone marrow failure syndrome with leukemia predisposition. An understanding of the hematologic complications of SDS with age could guide clinical management, but data are limited for this rare disease. We conducted a cohort study of 153 subjects from 143 families with confirmed biallelic SBDSmutations enrolled on the North American Shwachman Diamond Registry or Bone Marrow Failure Registry. The SBDSc.258+2T>C variant was present in all but one patient. To evaluate association of blood counts with age, a total of 2146 blood counts were analyzed for 119 subjects. Absolute neutrophil counts were positively associated with age (P<0.0001). Hemoglobin was also positively associated with age up to 18 years (P<0.0001) but thereafter the association was negative (P=0.0079). Platelet counts and marrow cellularity were negatively associated with age (P<0.0001). Marrow cellularity did not correlate with blood counts. Severe marrow failure necessitating transplant developed in 8 subjects at a median age of 1.7 years (range 0.4-39.5), with 7 of 8 requiring transplant prior to age 8 years. Twenty-six subjects (17%) developed a myeloid malignancy (16 MDS and 10 AML) at a median age of 12.3 years (range 0.5-45.0) for MDS, and 28.4 years (range 14.4-47.3) for AML. A lymphoid malignancy developed in one patient at the age of 16.9 years. Hematologic complications were the major cause of mortality (17/20 deaths, 85%). These data inform surveillance of hematologic complications in SDS.

Kuter: Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Dova: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Argenx: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Agios: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Actelion (Syntimmune): Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Protalex: Consultancy, Honoraria, Research Funding; Shionogi: Consultancy; UCB: Consultancy, Honoraria; Platelet Disorder Support Association: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Caremark: Consultancy, Honoraria; CRICO: Consultancy, Honoraria; Immunovant: Other: Travel Expenses, Research Funding; Kezar Life Sciences, Inc: Other, Research Funding; Principia Biopharma: Consultancy, Honoraria, Other, Research Funding; Protalex: Consultancy, Honoraria, Other, Research Funding; Sanofi (Genzyme): Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Immunovant: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Kyowa-Kirin: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; Protalix Biotherapeutics: Consultancy; Principia: Consultancy, Research Funding; Shire: Consultancy, Honoraria; Shionogi: Consultancy, Honoraria; Up-To-Date: Consultancy, Honoraria, Patents & Royalties; Zafgen: Consultancy, Honoraria; Takeda (Bioverativ): Consultancy, Honoraria, Other, Research Funding; Rigel: Consultancy, Honoraria, Other, Research Funding; Alnylam: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding. Rees:AstraZeneca: Other: Data monitoring committee membership; Novartis: Consultancy, Honoraria; TauRx: Other: Data And Safety Monitoring; Alnylam Pharmaceuticals: Consultancy, Honoraria; Emmanus Medical: Consultancy, Honoraria. Ventura:Alnylam Pharmaceuticals: Consultancy, Honoraria; Recordati Rare Diseases: Consultancy, Honoraria. Balwani:Recordati Rare Diseases: Consultancy, Honoraria, Other: Disease information video recording; Alnylam Pharmaceuticals: Consultancy, Honoraria, Research Funding. Gouya:Alnylam Pharmaceuticals: Consultancy, Honoraria, Other: Scientific meeting. Simon:Alnylam Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Liu:Alnylam Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Ko:Alnylam Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Rhyee:Alnylam Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Silver:Alnylam Pharmaceuticals: Other: Travel reimbursement, Research Funding; Blue Care Network: Consultancy; Oncology Business Review: Speakers Bureau.

Introduction:Acute hepatic porphyria (AHP) is a family of rare genetic diseases due to enzyme defects in hepatic heme biosynthesis. Induction of 5-aminolevulinic acid synthase 1 (ALAS1), the rate-limiting step in heme biosynthesis, leads to accumulation of heme intermediates, 5-aminolevulinic acid (ALA) and porphobilinogen (PBG) that may result in neurovisceral attacks. ENVISION (NCT03338816) is an ongoing study, evaluating efficacy and safety of givosiran in symptomatic AHP patients in a 6-month double blind (DB) period and a 30-month open label extension (OLE) period. While the efficacy and safety profile of givosiran has previously been reported in the DB period, here its effect through Month 18 of the OLE period is reported.

Genetic lesions that reduce telomerase activity inhibit stem cell replication and cause a range of incurable diseases, including dyskeratosis congenita (DC) and pulmonary fibrosis (PF). Modalities to restore telomerase in stem cells throughout the body remain unclear. Here, we describe small-molecule PAPD5 inhibitors that demonstrate telomere restoration in vitro, in stem cell models, and in vivo. PAPD5 is a non-canonical polymerase that oligoadenylates and destabilizes telomerase RNA component (TERC). We identified BCH001, a specific PAPD5 inhibitor that restored telomerase activity and telomere length in DC patient induced pluripotent stem cells. When human blood stem cells engineered to carry DC-causing PARNmutations were xenotransplanted into immunodeficient mice, oral treatment with a repurposed PAPD5 inhibitor, the dihydroquinolizinone RG7834, rescued TERC 3′ end maturation and telomere length. These findings pave the way for developing systemic telomere therapeutics to counteract stem cell exhaustion in DC, PF, and possibly other aging-related diseases.

Background:We recently found that CLAG-M was safe and produced higher rates of CR/CRi and higher measurable residual disease (MRD)-negative CR (measured by multiparameter flow cytometry [MFC]) than standard “7+3” therapy in fit patients with newly-diagnosed AML or other high-grade myeloid neoplasm with ≥10% blasts (HG-MN). Since addition of the CD33 antibody-drug conjugate gemtuzumab ozogamicin (GO) to chemotherapy reduces relapse risk and improves survival in some AML patients, we conducted a phase 1 study (NCT03531918) to determine the maximum tolerated dose (MTD) of GO with CLAG-M in fit adults with newly-diagnosed AML (APL excluded) or HG-MN.

Halpern: Pfizer Pharmaceuticals: Research Funding; Bayer Pharmaceuticals: Research Funding. Othus:Glycomimetics: Other: Data Safety and Monitoring Committee; Celgene: Other: Data Safety and Monitoring Committee. Buckley:CTI Biopharma: Employment. Percival:Pfizer Inc.: Research Funding; Nohla Therapeutics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees. Becker:The France Foundation: Honoraria; Accordant Health Services/Caremark: Consultancy; AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding. Scott:Incyte: Consultancy; Novartis: Consultancy; Agios: Consultancy; Celgene: Consultancy. Oehler:Pfizer Inc.: Research Funding; Blueprint Medicines: Consultancy; NCCN: Consultancy. Gernsheimer:Bioverativ: Consultancy; Novartis: Honoraria; Dova pharmaceuticals: Consultancy; Shionogi: Consultancy; Rigel: Consultancy; Fuji film: Consultancy; Amgen: Consultancy, Honoraria; Cellphire: Consultancy. Orozco:Actinium Pharmaceuticals: Research Funding. Cassaday:Seattle Genetics: Other: Spouse's disclosure: employment, stock and other ownership interests; Amgen: Consultancy, Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Research Funding. Shustov:Seattle Genetics, Inc.: Research Funding. Hartley:Pfizer Inc.: Employment, Equity Ownership. Welch:Pfizer Inc: Employment, Equity Ownership. Walter:Seattle Genetics: Research Funding; Jazz Pharmaceuticals: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Agios: Consultancy; Amgen: Consultancy; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Daiichi Sankyo: Consultancy; New Link Genetics: Consultancy; Pfizer: Consultancy, Research Funding; Kite Pharma: Consultancy; Covagen: Consultancy; Boston Biomedical: Consultancy; Race Oncology: Consultancy.

Halpern: Pfizer Pharmaceuticals: Research Funding; Bayer Pharmaceuticals: Research Funding. Othus:Glycomimetics: Other: Data Safety and Monitoring Committee; Celgene: Other: Data Safety and Monitoring Committee. Buckley:CTI BioPharma: Employment, Equity Ownership. Percival:Pfizer Inc.: Research Funding; Nohla Therapeutics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees. Becker:The France Foundation: Honoraria; AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding; Accordant Health Services/Caremark: Consultancy. Scott:Novartis: Consultancy; Agios: Consultancy; Incyte: Consultancy; Celgene: Consultancy. Oehler:Pfizer Inc.: Research Funding; Blueprint Medicines: Consultancy; NCCN: Consultancy. Gernsheimer:Fuji film: Consultancy; Bioverativ: Consultancy; Dova pharmaceuticals: Consultancy; Novartis: Honoraria; Cellphire: Consultancy; Amgen: Consultancy, Honoraria; Rigel: Consultancy; Shionogi: Consultancy. Orozco:Actinium Pharmaceuticals: Research Funding. Cassaday:Amgen: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Kite/Gilead: Research Funding; Merck: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Other: Spouse's disclosure: employment, stock and other ownership interests. Shustov:Seattle Genetics, Inc.: Research Funding. Hartley:Pfizer Inc.: Employment, Equity Ownership. Welch:Pfizer Inc: Employment, Equity Ownership. Walter:Agios: Consultancy; Amgen: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Boston Biomedical: Consultancy; Covagen: Consultancy; Daiichi Sankyo: Consultancy; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; New Link Genetics: Consultancy; Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy; Seattle Genetics: Research Funding.

Othus: Celgene: Membership on an entity's Board of Directors or advisory committees; Glycomimetics: Membership on an entity's Board of Directors or advisory committees. Percival:Nohla Therapeutics: Research Funding; Pfizer Inc.: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees. Scott:Agios: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Incyte: Consultancy. Becker:The France Foundation: Honoraria; Accordant Health Services/Caremark: Consultancy; AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding. Gardner:Abbvie: Speakers Bureau. Oehler:Pfizer Inc.: Research Funding; Blueprint Medicines: Consultancy; NCCN: Consultancy. Halpern:Pfizer Pharmaceuticals: Research Funding; Bayer Pharmaceuticals: Research Funding. Walter:Agios: Consultancy; Amgen: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Boston Biomedical: Consultancy; Covagen: Consultancy; Daiichi Sankyo: Consultancy; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; New Link Genetics: Consultancy; Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy; Seattle Genetics: Research Funding.Cladribine is not approved for AML, only Hairy Cell Leukemia, however it is widely used for AML with literature supporting it.

DiNardo: Karyopharm: Honoraria; Agios: Consultancy; Medimmune: Honoraria; Celgene: Honoraria; Bayer: Honoraria; Abbvie: Honoraria. Nichols:Incyte: Research Funding; Alpine Immune Sciences: Research Funding. Plon:Baylor Genetics: Membership on an entity's Board of Directors or advisory committees.

Clinical Genome Resource (ClinGen) is an NIH/NHGRI-funded effort dedicated to building an authoritative central resource that defines the clinical relevance of genes and variants for use in precision medicine and research. ClinGen has developed both gene and variant expert panels to adapt the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines for consistent and accurate variant classification of specific genes and diseases. Here, we describe a new effort initiated in 2018 and supported by the American Society of Hematology (ASH) in collaboration with ClinGen to develop expert panels. This effort was motivated by the increasing use of genomics in clinical hematology and the lack of resources containing expert interpretation of germline variation. This panel, named the ClinGen Myeloid Malignancy Variant Curation Expert Panel is focused on the curation and annotation of variants in genes associated with familial/inherited risk for myeloid malignancies. Our team consists of expert clinicians, clinical laboratory diagnosticians, and researchers interested in developing and implementing standardized protocols for sequence variant specific annotations of genes in inherited myeloid malignancies. The optimization of the ACMG/AMP guidelines encompasses disease-/gene-informed specifications or strength adjustments of existing rules, including defining gene-specific population frequency cutoffs, and specifying recommendations for the use of computational/predictive data, as supported by published functional and clinical data in addition to guidance on ACMG/AMP variant interpretation provided by the ClinGen effort. Our initial focus has been to organize sub-groups of teams to develop approaches for evaluating ACMG/AMP codes to interpret germline variants of the RUNX1gene. Once the curation of RUNX1variants is underway, we will extend our focus to include CEBPA, DDX41, ETV6, and GATA2. These efforts will be bolstered by encouraging submission of existing variant interpretations to ClinVar or other public variant databases by the Hematology community. In summary, the ClinGen Myeloid Malignancy Variant Curation Expert Panel aims to develop recommendations to optimize ACMG/AMP criteria for standardization of variant interpretation in myeloid leukemia genes and make expert-reviewed and interpreted variants available to the hematology community through ClinVar and the ClinGen website (www.clinicalgenome.org) to support patient care and research.

Genetic predisposition to MDS and AML is recognized in a growing subset of patients, but data to inform medical management and outcomes are sparse. Shwachman-Diamond syndrome (SDS) is an inherited marrow failure syndrome associated with increased risk of myelodysplasia (MDS) and acute myeloid leukemia (AML). The aim of this multi-institutional retrospective study was to investigate clinical features, treatment, and outcomes of 37 patients with SDS who developed MDS or AML. Diagnosis of SDS was established by SBDSgenetic testing (n=30), exocrine pancreatic dysfunction (n=5), or data were unavailable (n=2). Nine individuals presented with AML (4 male, 5 female), 26 with MDS (13 male and 13 female), one male with refractory cytopenia (RC), and one male with isolated persistent somatic TP53 mutation. Eight of 26 MDS patients, had MDS-EB1 or EB2 at diagnosis, of whom two progressed to AML. Three patients initially presenting with early MDS progressed to MDS-EB1, MDS-EB2, or AML. Median age (years) at diagnosis of early MDS was 13.8 (range 0.5-28.8), for MDS-EB1/2 was 16 (range 9-30) and for AML was 33 (range 5.5-47). Nine patients with MDS and 1 patient with AML were receiving G-CSF chronically prior to diagnosis of MDS/AML.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

van Besien: Miltenyi Biotec: Research Funding. Godley:Onconova: Research Funding.

Shwachman-Diamond syndrome (SDS) is an inherited marrow failure syndrome associated with exocrine pancreatic dysfunction and an increased risk of myelodysplasia and leukemia. The majority of individuals with SDS carry biallelic SBDS gene mutations, however a subset of patients remain genetically undefined. The objective of this study was to compare the clinical characteristics of patients with and without SBDSmutations. To address these questions, we conducted a retrospective study of patients enrolled on the North American Shwachman-Diamond Syndrome Registry (SDSR). Clinical data from the SDSR were available for 55 individuals with biallelic SBDSmutations and 16 individuals who fulfilled clinical diagnostic criteria for SDS but lacked biallelic mutations in the SBDSgene. Study subject ages for SBDSmutation positive and negative cohorts span 2-52.4 and 2.8-21.4 years with median ages of 12.4 and 10.9 years respectively. Cytopenias were present for both SBDSmutation positive and negative cohorts, with neutropenia the most common event in 94% and 81% respectively. Bone marrow hypocellularity was reported in 91% of those with SBDSmutations and 69% of those without. Marrow dysplasia was reported in 65% of those with SBDS mutations and none of those without. Clonal abnormalities were present in 44% and 25% of those with and without SBDS mutations with median age of initial appearance at 9 years (0.8-45.1) and 7 years (1.2-14) respectively. Abnormalities included del7q and del20q in both groups as well as iso7q, trisomy 8 and others in the SBDSmutation positive group. Clonal abnormalities were all transient in the SBDSmutation negative cohort. One SBDSmutation positive individual developed AML. None of the SBDSmutation negative individuals developed malignancy or progressed to require HSCT thus far. Pancreatic dysfunction determined by low serum trypsinogen or pancreatic isoamylase was similar in both cohorts 79% vs 80%. However, only 27% (15/55) of SBDSmutation positive individuals reported requiring enzyme therapy with 33% (18/55) documenting failure to thrive, in contrast to 75% (12/16) of SBDSmutation negative individuals with 73% (11/15) having failure to thrive. A broad spectrum of congenital anomalies were reported in 55% and 56% of SBDSmutation positive and negative individuals respectively, with skeletal anomalies being the most common in both groups. Medical comorbidities commonly reported in both groups included eczema and endocrinopathies. Elevated liver transaminases were seen in 27% of SBDSmutation positive individuals but this was not seen in the SBDSmutation negative cohort.

Background

The classical Inherited Bone Marrow Failure Syndromes (IBMFS) such as Fanconi anemia, Dyskeratosis Congenita, Shwachman-Diamond syndrome, and Diamond-Blackfan anemia are a heterogeneous group of disorders, all of which are characterized by impaired hematopoiesis, varying degrees of peripheral cytopenias and marrow hypoplasia and dysplasia. Many of these are associated with an increased risk of clonal dominance and evolution to myelodyplastic syndrome (MDS) and acute myeloid leukemia (AML). For the purposes of this talk, the familial MDS and acute leukemia predisposition syndromes are also included in the broad term IBMFS. The genes responsible for a subset of IBMFS have been identified and will be reviewed. However, the causative mutations in many patients presenting with seemingly inherited marrow failure remain unknown. Gene discovery in IBMFS has been difficult in large part due to the phenotypic heterogeneity of these syndromes. Some patients with IBMFS display a distinct clinical phenotype with associated syndromic abnormalities, others are variable and overlap with one another or with acquired MDS or idiopathic acquired aplastic anemia, and additional cases are more obscure and have evaded classification altogether. Accurate diagnosis of IBMFS inform patient care as it allows appropriate screening of siblings to avoid choosing an affected donor if marrow transplant is indicated and the selection of an appropriate transplant conditioning regiment to avoid undue toxicity. Additionally, accurate diagnosis allows appropriate medical monitoring and early intervention to successfully treat disease-specific non-hematologic medical complications. The application of next generation sequencing approaches for comprehensive genetic screening of IBMFS, including these cryptic or atypical presentations will be reviewed. In addition to providing accurate diagnoses in a subset of patients, genetic characterization in small family kindreds or even in single individuals presents unique opportunities to discover new genes and pathways contributing to dysfunctional hematopoiesis and clonal progression. The frequency of inherited mutations in known IBMFS genes among seemingly idiopathic acquired aplastic anemia patients or pediatric and younger adults with MDS referred for hematopoietic stem cell transplant will be reviewed. Future genetic studies are needed to characterize the secondary genetic events that lead to disease progression in IBMFS.

Dale: Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Twenty-five percent of Diamond Blackfan anemia (DBA) cases result from haploinsufficiency of RPS19 and ~30% from haploinsufficiencies of other ribosomal proteins. The macrocytic anemia of del(5q) MDS results from RPS14 haploinsufficiency. When tested, these mutations disrupt ribosome assembly, yet how this causes macrocytic anemia remains uncertain. The dominant hypothesis is that P53 pathway activation leads to cell apoptosis, however, why erythropoiesis is severely impacted, while other hematopoietic as well as non-hematopoietic cells function appropriately, is difficult to explain. These observations led us to predict that DBA and del(5q) MDS share a pathogenesis that reflects the rapid kinetics of red cell and hemoglobin production, and specifically that poor ribosome assembly leads to an inability to quickly translate mRNA to protein, delayed globin synthesis in early erythroid precursors, and excess heme. Since free heme is toxic, cell death ensues. To explore this, we studied marrow from DBA (n=3) and del(5q) MDS (n=6) patients in cultures that optimize erythroid differentiation and showed that (a) cell numbers significantly decrease between stages I (lin-CD71+CD36-GlyA-)(BFU-E/early CFU-E) and II, (lin-CD71+CD36+GlyA-)(CFU-E/early proerythroblasts; Li et al. Blood2014;124:3636); and (b) the cells that survive this insult differentiate normally to stages III (lin-CD36+GlyA+) and IV (lin-CD36-GlyA+). Using marrow from the index DBA patient, a 28-year old transfusion-dependent female with inherited RPS19 haploinsufficiency, and (as available) marrow from other DBA and del(5q) MDS patients (n=2-7 patients per study), we demonstrated that heme synthesis (assessed by ALAS2mRNA and protein) initiates normally while globin production (α- and β-globin mRNA and protein) is slowed, and that stage I and II cells have excess heme. Next, to discern the cell-specific characteristics that allow a DBA or del(5q) MDS cell to survive and fully mature, we compared those cells able to advance to stages III and IV in patient and concurrent control cultures. Stage III-IV GlyA+DBA cells expressed 2.4-fold less ALAS2 mRNAand 2-fold more FLVCR mRNA than GlyA+control cells (p values<0.05). Since the levels of ALAS2 and FLVCR mRNA were similar in stage I DBA and control cells, the time when heme synthesis initiates, these data imply that DBA cells capable of down-regulating their heme synthesis (have less ALAS2) or content (have moreFLVCR and increased heme export) preferentially survive. Data from del(5q) MDS patients are similar - cells progressing to stages III and IV have 2.9-fold less ALAS2 mRNA (p<0.05) and 9.4-fold higher FLVCR mRNA (p<0.01) than control cells. That heme synthesis proceeds normally, while globin production initiates slowly, was confirmed by sequential sampling of marrow cultures at days 3, 7, 10, 13, and 17; and as expected, DBA and del(5q) MDS cells at day 7 had increased reactive oxygen species (ROS). Consistent with these observations, treatment with 10 μM succinylacetone, a specific inhibitor of heme synthesis, improved the erythroid cell output of DBA and del(5q) MDS cultures by 68-95% (p values<0.05), while the erythroid cell output of concurrent control cultures decreased by 4-13%. Cell death appears to result both from apoptosis (not shown) and ferroptosis, a ROS-induced process previously characterized in kidney epithelial cells and cancer cell lines (Dixon et al. Cell2012;149:1060). Recent data showing P53 sensitizes cells to ferroptosis by impeding the transcription of SCL7A11, a cysteine-glutamate antiporter, leading to less cysteine uptake, less GSH synthesis, less GPX4, and less antioxidants (Jiang et al. Nature2015;520:57) link our observations to work implicating P53 activation in DBA and del(5q) MDS anemia. In support of this connection, DBA marrow cells at culture day 10 have 57% less SLC7A11 mRNA than control cells in preliminary experiments. Together, our studies demonstrate that erythropoiesis fails when heme exceeds globin. The data also suggest that decreasing heme synthesis, either directly or by chelating iron, may improve these anemias. They further argue that lenalidomide (destabilizes P53) and therapies decreasing heme should be synergistic. Since diverse mutations could impede brisk protein transcription or translation, and hence brisk globin production, heme toxicity might also contribute to anemia in MDS patients without del(5q).

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Abstract 2307

Abstract 514

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Abstract SCI-24

Abstract 175

Abstract 681

Diamond-Blackfan Anemia (DBA) is a congenital form of pure red cell aplasia characterized by a hypoproliferative, macrocytic anemia, congenital anomalies, and a predisposition to cancer. DBA, along with a growing number of human diseases, is linked to defects in ribosome biogenesis. Mutations in at least 10 ribosomal protein genes of both the 40S and 60S ribosomal subunits have now been identified in over 50% of patients with DBA (Narla A, et al. Blood 2010; 115) resulting in ribosomal protein haploinsufficency and in turn a defect in ribosome biogenesis. It remains, however, unknown how these events culminate in erythroid marrow failure. The study of this pathophysiology has been hindered by a lack of animal models. We became aware of the Rps6-deleted mouse as a potential murine model of DBA (Volarevic S, et al. Science 2000; 288). RPS6 is another 40S ribosomal subunit protein required for ribosomal subunit assembly. Haploinsufficiency of RPS6 causes a phenotype reminiscent of DBA during embryogenesis (Panic L, et al. Mol Cell Biol 2006; 26), however, the erythropoietic phenotype of the conditionally-deleted Rps6 heterozygous mouse was unknown. The purpose of these studies is to fully characterize the erythroid phenotype of this mouse as a model of DBA. We demonstrate that deletion of one Rps6 allele in mice results in a macrocytic anemia and leukopenia (an absolute neutropenia and lymphocytopenia, Table 1). Though this finding is not typical, neutropenia has been described in DBA. Like DBA, the anemia is hypoproliferative (corrected reticulocyte counts were equivalent in rpS6 heterozygous and control mice: 3.3% ± 0.21, n= 3 vs. 3.6 ± 0.33, n=3; two-tailed Student's t-test, p= 0.08, which is an inappropriately low value given the deleted animals’ anemia).Flow cytometric analyses of bone marrow and spleen double-stained for Ter119 and transferrin receptor (CD71) demonstrate impaired early erythroid differentiation, evidenced by a relative expansion in the proerythroblast and basophilic erythroblast populations. Hematopoietic colony assays confirm this early defect. These data suggest that haploinsufficiency of rpS6 impacts both erythropoiesis and granulopoiesis, and since the mice are not thrombocytopenic, the effect appears lineage specific, rather than occurring in a common progenitor cell. Polysome profiles to confirm a defect in ribosome biogenesis are pending. Since heterozygous mice recapitulate the erythroid phenotype of DBA, we treated the mice with standard and potential DBA therapies. Specifically, mice received 2 mg/kg/day of prednisone for 12 weeks. There was no improvement in the hemoglobin or MCV in treated animals. As DBA and 5q- syndrome myelodysplastic syndrome (MDS) share an erythroid phenotype and both result from a haploinsufficiency of a ribosomal protein, we also tested whether the macrocytic anemia in rpS6 heterozygous mice responds to lenalidomide (Revlimid®, gift from Celgene Corporation, San Diego, CA). Mice received 3 mg/kg/day of lenalidomide by oral gavage for 12 weeks. The hemoglobin increased in control mice and markedly increased in rpS6 heterozygous mice after 12 weeks of therapy (13.5 ± 0.4 to 14.9 ± 0.2, p= 0.0 and 7.9 g/dL ± 0.9 to 10.3 ± 0.8, p= 0.01, respectively; mean ± SEM, Student's t-test, paired). Additionally, the MCV decreased with therapy in both groups (49.1 fL ± 1.4 to 41.1 ± 0.2, p=0.005 and 57.4 ± 1.1 to 53.77 ± 1.4, p=0.08). With the caveat that we did not monitor drug levels achieved in vivo, these data suggest that lenalidomide improves hemoglobinization and deserves further study in DBA.No relevant conflicts of interest to declare.

Abstract 2033