Implementation of and Systems-Level Barriers to Guideline-Driven Germline Genetic Evaluation in the Care of Patients With Myelodysplastic Syndrome and Acute Myeloid Leukemia.

PURPOSE: Knowledge of an inherited predisposition to myelodysplastic syndrome (MDS) and AML has important clinical implications for treatment decisions, surveillance, and care of at-risk relatives. National Comprehensive Cancer Network (NCCN) guidelines recently incorporated recommendations for germline genetic evaluation of patients with MDS/AML on the basis of personal and family history features, but the practicality of implementing these recommendations has not been studied. METHODS: A hereditary hematology quality improvement (QI) committee was formed to implement these guidelines in a prospective cohort of patients diagnosed with MDS/AML. Referral for germline genetic testing was recommended for patients meeting NCCN guideline criteria. Referral patterns and genetic evaluation outcomes were compared with a historical cohort of patients with MDS/AML. Barriers to evaluation were identified. RESULTS: Of the 90 patients with MDS/AML evaluated by the QI committee, 59 (66%) met criteria for germline evaluation. Implementation of the QI committee led to more referrals for germline evaluation in accordance with NCCN guidelines (31% v 14%, P = .03). However, the majority of those meeting criteria were never referred due to high medical acuity or being deceased or in hospice at the time of QI committee recommendations. Despite this, two (17%) of the 12 patients undergoing genetic testing were diagnosed with a hereditary myeloid malignancy syndrome. CONCLUSION: Current NCCN guidelines resulted in two thirds of patients with MDS/AML meeting criteria for germline evaluation. A hereditary hematology-focused QI committee aided initial implementation and modestly improved NCCN guideline adherence. However, the high morbidity and mortality and prolonged inpatient stays associated with MDS/AML challenged traditional outpatient genetic counseling models. Further improvements in guideline adherence require innovating new models of genetic counseling and testing for this patient population.

Implementation of a prospective screening strategy to identify adults with a telomere biology disorder among those undergoing lung transplant evaluation for interstitial lung disease.

INTRODUCTION: Patients with interstitial lung disease (ILD) secondary to telomere biology disorders (TBD) experience increased morbidity after lung transplantation. Identifying patients with TBD may allow for personalized management to facilitate better outcomes. However, establishing a TBD diagnosis in adults is challenging. METHODS: A TBD screening questionnaire was introduced prospectively into the lung transplant evaluation. Patients with ILD screening positive were referred for comprehensive TBD phenotyping and concurrent telomere length measurement and germline genetic testing. RESULTS: Of 98 patients, 32 (33%) screened positive. Eight patients (8% of total; 25% of patients with a positive screen) met strict TBD diagnostic criteria, requiring either critically short lymphocyte telomeres (<1st percentile) (n = 4), a pathogenic variant in a TBD-associated gene (n = 1), or both (n = 3) along with a TBD clinical phenotype. Additional patients not meeting strict diagnostic criteria had histories consistent with TBD along with telomere lengths <10th percentile and/or rare variants in TBD-associated genes, highlighting a critical need to refine TBD diagnostic criteria for this patient population. CONCLUSION: A TBD phenotype screening questionnaire in patients with ILD undergoing lung transplant evaluation has a diagnostic yield of 25%. Additional gene discovery, rare variant functional testing, and refined TBD diagnostic criteria are needed to realize the maximum benefit of testing for TBD in patients undergoing lung transplantation.

Neighborhood disadvantage, insurance status, and molecular profiling of patients with acute myeloid leukemia.

Next-generation sequencing (NGS) is important for prognostication and determining eligibility for targeted therapies in acute myeloid leukemia (AML). The use of NGS has increased in clinical practice, but variability in testing patterns still exist. The purpose of this study was to assess trends in molecular genetic sequencing in AML based on insurance status and area deprivation index (ADI), a validated metric of neighborhood disadvantage. Patient demographics, clinical characteristics, cytogenetic and molecular data, and treatment patterns were collected retrospectively for 275 patients diagnosed with AML at a single institution. No significant differences in practice patterns and patient outcomes based on ADI rank were observed. In contrast, patients with Medicare or underinsured status were less likely to have genetic sequencing performed, were treated with less intensive regimens, and had inferior overall survival compared to those with Medicaid or private insurance. On univariate analysis, molecular genetic sequencing was associated with improved overall survival, suggesting that NGS data allows for better risk stratification and more informed therapeutic decision-making. These data highlight the current barriers to molecular genetic sequencing, demonstrate the positive benefits of NGS on clinical outcomes, and support universal coverage of NGS for all patients with AML.

Role of ASXL1 in hematopoiesis and myeloid diseases.

Next-generation sequencing technology, including whole-exome or whole-genome sequencing and target gene sequencing, has allowed the molecular characterization of somatic mutation spectrums in hematologic diseases. Mutations in Additional sex combs-like 1 (ASXL1), a chromatin regulator, are identified in clonal hematopoiesis of indeterminate potential (CHIP), indicating ASXL1 mutations as early events in leukemogenesis. Not surprisingly, they occur at high frequency in myeloid malignancies and are associated with poor prognosis. Therefore, understanding how mutant ASXL1 drives clonal expansion and leukemogenesis will serve as the basis for the future development of preventative and/or therapeutic strategies for myeloid diseases with ASXL1 mutations. Here, we discuss the biology of ASXL1 and its role in controlling normal and malignant hematopoiesis. In addition, we review the clinical relevance of ASXL1 mutations in CHIP and myeloid diseases.

A Case of Isolated Myeloid Sarcoma Associated With Germline EGFR T790M Variant: The Importance of Recognizing Potential Germline Variants on Somatic Tumor Sequencing Panels.

Isolated myeloid sarcoma is an uncommon subtype of acute myeloid leukemia associated with variable prognosis. We present the case of a previously healthy 30-year-old man presenting with chest pain and weight loss who was found to have a large mediastinal mass. Biopsy of the mass was consistent with isolated myeloid sarcoma. A somatic tumor sequencing panel revealed an EGFR T790M variant, which was later confirmed to be of germline origin. Germline EGFR T790M variants are associated with a hereditary predisposition to lung cancer, though myeloid malignancies have not yet been described. To our knowledge, this is the first reported case of myeloid sarcoma in a patient with an underlying germline EGFR T790M mutation. As somatic tumor sequencing panels become more commonplace, it is important to recognize potential germline variants in order to facilitate appropriate referral for genetic counseling, perform confirmatory genetic testing, and to develop a personalized treatment and surveillance plan for patients and their families.

Clinical utility and real-world application of molecular genetic sequencing in the management of patients with acute myeloid leukemia and myelodysplastic syndromes.

Recurrently mutated genes in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) have proven useful in risk stratification and clinical decision-making. Sequencing technologies that detect these genetic mutations are now widely available, though there is variability in the use of such data among hematologists. Molecular genetic sequencing trends were assessed in 470 patients presenting to a single institution with AML or MDS to determine how molecular data impacts clinical management of patients with myeloid malignancies. Patients with AML were more likely to have molecular genetic sequencing performed compared to patients with MDS, and clinicians were more likely to reference molecular data in decision-making for patients with AML. Furthermore, the presence of molecular data was associated with an increased odd of bone marrow transplantation (BMT). This study demonstrates the real-world application of molecular data in the management of myeloid malignancies and also highlights disparities in the use of such data based on diagnosis.

Circulating exosomal microRNAs in acquired aplastic anemia and myelodysplastic syndromes.

Exosomal microRNAs modulate cancer cell metabolism and the immune response. Specific exosomal microRNAs have been reported to be reliable biomarkers of several solid and hematologic malignancies. We examined the possible diagnostic and prognostic values of exosomal microRNAs in two human bone marrow failure diseases: aplastic anemia and myelodysplastic syndromes. After screening 372 microRNAs in a discovery set (n=42) of plasma exosome samples, we constructed a customized PCR plate, including 42 microRNAs, for validation in a larger cohort (n=99). We identified 25 differentially expressed exosomal microRNAs uniquely or frequently present in aplastic anemia and/or myelodysplastic syndromes. These microRNAs could be related to intracellular functions, such as metabolism, cell survival, and proliferation. Clinical parameters and progression-free survival were correlated to microRNA expression levels in aplastic anemia and myelodysplastic syndrome patients before and after six months of immunosuppressive therapy. One microRNA, mir-126-5p, was negatively correlated with a response to therapy in aplastic anemia: patients with higher relative expression of miR-126-5p at diagnosis had the shortest progression-free survival compared to those with lower or normal levels. Our findings suggest utility of exosomal microRNAs in the differential diagnosis of bone marrow failure syndromes. (Registered at clinicaltrials.gov identifiers: 00260689, 00604201, 00378534, 01623167, 00001620, 00001397, 00217594).

CRISPR/Cas9-mediated ASXL1 mutations in U937 cells disrupt myeloid differentiation.

Additional sex combs-like 1 (ASXL1) is a well­known tumor suppressor gene and epigenetic modifier. ASXL1 mutations are frequent in myeloid malignances; these mutations are risk factors for the development of myelodysplasia and also appear as small clones during normal aging. ASXL1 appears to act as an epigenetic regulator of cell survival and myeloid differentiation; however, the molecular mechanisms underlying the malignant transformation of cells with ASXL1 mutations are not well defined. Using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein-9 nuclease (Cas9) genome editing, heterozygous and homozygous ASXL1 mutations were introduced into human U937 leukemic cells. Comparable cell growth and cell cycle progression were observed between wild-type (WT) and ASXL1-mutated U937 cells. Drug-induced cytotoxicity, as measured by growth inhibition and apoptosis in the presence of the cell-cycle active agent 5-fluorouracil, was variable among the mutated clones but was not significantly different from WT cells. In addition, ASXL1-mutated cells exhibited defects in monocyte/macrophage differentiation. Transcriptome analysis revealed that ASXL1 mutations altered differentiation of U937 cells by disturbing genes involved in myeloid differentiation, including cytochrome B-245 ß chain and C-type lectin domain family 5, member A. Dysregulation of numerous gene sets associated with cell death and survival were also observed in ASXL1-mutated cells. These data provide evidence regarding the underlying molecular mechanisms induced by mutated ASXL1 in leukemogenesis.

Abnormal RNA splicing and genomic instability after induction of DNMT3A mutations by CRISPR/Cas9 gene editing.

DNA methyltransferase 3A (DNMT3A) mediates de novo DNA methylation. Mutations in DNMT3A are associated with hematological malignancies, most frequently acute myeloid leukemia. DNMT3A mutations are hypothesized to establish a pre-leukemic state, rendering cells vulnerable to secondary oncogenic mutations and malignant transformation. However, the mechanisms by which DNMT3A mutations contribute to leukemogenesis are not well-defined. Here, we successfully created four DNMT3A-mutated K562 cell lines with frameshift mutations resulting in truncated DNMT3A proteins. DNMT3A-mutated cell lines exhibited significantly impaired growth and increased apoptotic activity compared to wild-type (WT) cells. Consistent with previous studies, DNMT3A-mutated cells displayed impaired differentiation capacity. RNA-seq was used to compare transcriptomes of DNMT3A-mutated and WT cells; DNMT3A ablation resulted in downregulation of genes involved in spliceosome function, causing dysfunction of RNA splicing. Unexpectedly, we observed DNMT3A-mutated cells to exhibit marked genomic instability and an impaired DNA damage response compared to WT. CRISPR/Cas9-mediated DNMT3A-mutated K562 cells may be used to model effects of DNMT3A mutations in human cells. Our findings implicate aberrant splicing and induction of genomic instability as potential mechanisms by which DNMT3A mutations might predispose to malignancy.