Assessment of technical heterogeneity among diagnostic tests to detect germline risk variants for hematopoietic malignancies

Germline Predisposition in Hematologic Malignancies: Testing, Management, and Implications

Although numerous barriers for clinical germline cancer predisposition testing exist, the increasing recognition of deleterious germline DNA variants contributing to myeloid malignancy risk is yielding steady improvements in referrals for testing and testing availability. Many germline predisposition alleles are common in populations, and the increasing number of recognized disorders makes inherited myeloid malignancy risk an entity worthy of consideration for all patients regardless of age at diagnosis. Germline testing is facilitated by obtaining DNA from cultured skin fibroblasts or hair bulbs, and cascade testing is easily performed via buccal swab, saliva, or blood. Increasingly as diagnostic criteria and clinical management guidelines include germline myeloid malignancy predisposition, insurance companies recognize the value of testing and provide coverage. Once an individual is recognized to have a deleterious germline variant that confers risk for myeloid malignancies, a personalized cancer surveillance plan can be developed that incorporates screening for other cancer risk outside of the hematopoietic system and/or other organ pathology. The future may also include monitoring the development of clonal hematopoiesis, which is common for many of these cancer risk disorders and/or inclusion of strategies to delay or prevent progression to overt myeloid malignancy. As research continues to identify new myeloid predisposition disorders, we may soon recommend testing for these conditions for all patients diagnosed with a myeloid predisposition condition.

Unraveling germline predisposition in hematological neoplasms: Navigating complexity in the genomic era

Genomic advancements have yielded pivotal insights into hematological neoplasms, particularly concerning germline predisposition mutations. Following the WHO 2016 revisions, dedicated segments were proposed to address these aspects. Current WHO 2022, ICC 2022, and ELN 2022 classifications recognize their significance, introducing more mutations and prompting integration into clinical practice. Approximately 5-10% of hematological neoplasm patients show germline predisposition gene mutations, rising with risk factors such as personal cancer history and familial antecedents, even in older adults. Nevertheless, technical challenges persist. Optimal DNA samples are skin fibroblast-extracted, although not universally applicable. Alternatives such as hair follicle use are explored. Moreover, the scrutiny of germline genomics mandates judicious test selection to ensure precise and accurate interpretation. Given the significant influence of genetic counseling on patient care and post-assessment procedures, there arises a demand for dedicated centers offering specialized services.

Diagnosis and classification of myelodysplastic syndromes

ABSTRACT

Myelodysplastic syndromes (MDSs) are neoplastic myeloid proliferations characterized by ineffective hematopoiesis resulting in peripheral blood cytopenias. MDS is distinguished from nonneoplastic clonal myeloid proliferations by the presence of morphologic dysplasia and from acute myeloid leukemia by a blast threshold of 20%. The diagnosis of MDS can be challenging because of the myriad other causes of cytopenias: accurate diagnosis requires the integration of clinical features with bone marrow and peripheral blood morphology, immunophenotyping, and genetic testing. MDS has historically been subdivided into several subtypes by classification schemes, the most recent of which are the International Consensus Classification and World Health Organization Classification (fifth edition), both published in 2022. The aim of MDS classification is to identify entities with shared genetic underpinnings and molecular pathogenesis, and the specific subtype can inform clinical decision-making alongside prognostic risk categorization. The current MDS classification schemes incorporate morphologic features (bone marrow and blood blast percentage, degree of dysplasia, ring sideroblasts, bone marrow fibrosis, and bone marrow hypocellularity) and also recognize 3 entities defined by genetics: isolated del(5q) cytogenetic abnormality, SF3B1 mutation, and TP53 mutation. It is anticipated that with advancing understanding of the genetic basis of MDS pathogenesis, future MDS classification will be based increasingly on genetic classes. Nevertheless, morphologic features in MDS reflect the phenotypic expression of the underlying abnormal genetic pathways and will undoubtedly retain importance to inform prognosis and guide treatment.

Germ line variants in patients with acute myeloid leukemia without a suspicion of hereditary hematologic malignancy syndrome

Germ line predisposition in acute myeloid leukemia (AML) has gained attention in recent years because of a nonnegligible frequency and an impact on management of patients and their relatives. Risk alleles for AML development may be present in patients without a clinical suspicion of hereditary hematologic malignancy syndrome. In this study we investigated the presence of germ line variants (GVs) in 288 genes related to cancer predisposition in 47 patients with available paired, tumor-normal material, namely bone marrow stroma cells (n = 29), postremission bone marrow (n = 17), and saliva (n = 1). These patients correspond to 2 broad AML categories with heterogeneous genetic background (AML myelodysplasia related and AML defined by differentiation) and none of them had phenotypic abnormalities, previous history of cytopenia, or strong cancer aggregation. We found 11 pathogenic or likely pathogenic variants, 6 affecting genes related to autosomal dominant cancer predisposition syndromes (ATM, DDX41, and CHEK2) and 5 related to autosomal recessive bone marrow failure syndromes (FANCA, FANCM, SBDS, DNAJC21, and CSF3R). We did not find differences in clinical characteristics nor outcome between carriers of GVs vs noncarriers. Further studies in unselected AML cohorts are needed to determine GV incidence and penetrance and, in particular, to clarify the role of ATM nonsense mutations in AML predisposition.

Clinical guideline variability in the diagnosis of hereditary hematopoietic malignancy syndromes

A growing understanding of the complexities of hematopoietic malignancies necessitates the existence of clinical recommendations that are sufficiently comprehensive. Although hereditary hematopoietic malignancies (HHMs) are increasingly recognized for conferring risk of myeloid malignancy, frequently utilized clinical recommendations have never been appraised for the ability to reliably guide HHM evaluation. We assessed established society-level clinical guidelines for inclusion of critical HHM genes and graded the strength of testing recommendations. We uncovered a substantial lack of consistency of recommendations guiding HHM evaluation. Such heterogeneity in guidelines likely contributes to refusal by payers to support HHM testing, leading to underdiagnoses and lost opportunities for clinical surveillance.

Clinical considerations at the intersection of hematopoietic cell transplantation and hereditary hematopoietic malignancy

In recent years, advances in genetics and the integration of clinical-grade next-generation sequencing (NGS) assays into patient care have facilitated broader recognition of hereditary hematopoietic malignancy (HHM) among clinicians, in addition to the identification and characterization of novel HHM syndromes. Studies on genetic risk distribution within affected families and unique considerations of HHM biology represent exciting areas of translational research. More recently, data are now emerging pertaining to unique aspects of clinical management of malignancies arising in the context of pathogenic germline mutations, with particular emphasis on chemotherapy responsiveness. In this article, we explore considerations surrounding allogeneic transplantation in the context of HHMs. We review pre- and post-transplant patient implications, including genetic testing donor selection and donor-derived malignancies. Additionally, we consider the limited data that exist regarding the use of transplantation in HHMs and safeguards that might be pursued to mitigate transplant-related toxicities.

Genomic profiling for clinical decision making in myeloid neoplasms and acute leukemia

Myeloid neoplasms and acute leukemias derive from the clonal expansion of hematopoietic cells driven by somatic gene mutations. Although assessment of morphology plays a crucial role in the diagnostic evaluation of patients with these malignancies, genomic characterization has become increasingly important for accurate diagnosis, risk assessment, and therapeutic decision making. Conventional cytogenetics, a comprehensive and unbiased method for assessing chromosomal abnormalities, has been the mainstay of genomic testing over the past several decades and remains relevant today. However, more recent advances in sequencing technology have increased our ability to detect somatic mutations through the use of targeted gene panels, whole-exome sequencing, whole-genome sequencing, and whole-transcriptome sequencing or RNA sequencing. In patients with myeloid neoplasms, whole-genome sequencing represents a potential replacement for both conventional cytogenetic and sequencing approaches, providing rapid and accurate comprehensive genomic profiling. DNA sequencing methods are used not only for detecting somatically acquired gene mutations but also for identifying germline gene mutations associated with inherited predisposition to hematologic neoplasms. The 2022 International Consensus Classification of myeloid neoplasms and acute leukemias makes extensive use of genomic data. The aim of this report is to help physicians and laboratorians implement genomic testing for diagnosis, risk stratification, and clinical decision making and illustrates the potential of genomic profiling for enabling personalized medicine in patients with hematologic neoplasms.

Integrating germline variant assessment into routine clinical practice for myelodysplastic syndrome and acute myeloid leukaemia: current strategies and challenges

Over the last decade, the field of hereditary haematological malignancy syndromes (HHMSs) has gained increasing recognition among clinicians and scientists worldwide. Germline mutations now account for almost 10% of adult and paediatric myelodysplasia/acute myeloid leukaemia (MDS/AML). As our ability to diagnose HHMSs has improved, we are now faced with the challenges of integrating these advances into routine clinical practice for patients with MDS/AML and how to optimise management and surveillance of patients and asymptomatic carriers. Discoveries of novel syndromes combined with clinical, genetic and epigenetic profiling of tumour samples, have highlighted unique patterns of disease evolution across HHMSs. Despite these advances, causative lesions are detected in less than half of familial cases and evidence-based guidelines are often lacking, suggesting there is much still to learn. Future research efforts are needed to sustain current momentum within the field, led not only by advancing genetic technology but essential collaboration between clinical and academic communities.

Application of Next-Generation Sequencing-Based Mutational Profiling in Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Recent efforts to characterize hematologic cancers with genetic and molecular detail have largely relied on mutational profiling via next-generation sequencing (NGS). The application of NGS-guided disease prognostication and clinical decision making requires a basic understanding of sequencing advantages, pitfalls, and areas where clinical care might be enhanced by the knowledge generated. This article identifies avenues within the landscape of adult acute lymphoblastic leukemia (ALL) where mutational data hold the opportunity to enhance understanding of disease biology and patient care.

RECENT FINDINGS

NGS-based assessment of measurable residual disease (MRD) after ALL treatment allows for a sensitive and specific molecular survey that is at least comparable, if not superior, to existing techniques. Mutational assessment by NGS has unraveled complex signaling networks that drive pathogenesis of T-cell ALL. Sequencing of patients with familial clustering of ALL has also identified novel germline mutations whose inheritance predisposes to disease development in successive generations. While NGS-based assessment of hematopoietic malignancies often provides actionable information to clinicians, patients with acute lymphoblastic leukemia are left underserved due to a lack of disease classification and prognostication schema that integrate molecular data. Ongoing research is positioned to enrich the molecular toolbox available to clinicians caring for adult ALL patients and deliver new insights to guide therapeutic selection, monitor clinical response, and detect relapse.

Genetics of Myelodysplastic Syndromes

Myelodysplastic syndrome (MDS) describes a heterogeneous group of bone marrow diseases, now understood to reflect numerous germline and somatic drivers, characterized by recurrent cytogenetic abnormalities and gene mutations. Precursor conditions including clonal hematopoiesis of indeterminate potential and clonal cytopenia of undetermined significance confer risk for MDS as well as other hematopoietic malignancies and cardiovascular complications. The future is likely to bring an understanding of those individuals who are at the highest risk of progression to MDS and preventive strategies to prevent malignant transformation.

Germline predisposition to haematopoietic malignancies

Once thought to be exceedingly rare, the advent of next-generation sequencing has revealed a plethora of germline predisposition disorders that confer risk for haematopoietic malignancies (HMs). These syndromes are now recognized to be much more common than previously thought. The recognition of a germline susceptibility risk allele in an individual impacts the clinical management and health surveillance strategies in the index patient and relatives who share the causative DNA variant. Challenges to accurate clinical testing include a lack of familiarity in many health care providers, the requirement for DNA samples that reasonably approximate the germline state, and a lack of standardization among diagnostic platforms as to which genes are sequenced and their capabilities in detecting the full range of variant types that confer risk. Current knowledge gaps include a comprehensive understanding of all predisposition genes; whether scenarios exist in which an allogeneic stem cell transplant using donor haematopoietic stem cells with deleterious variants is permissive; and effective means of delivering genetic counseling and results disclosure for these conditions. We are hopeful that comprehensive germline genetic testing, universal germline testing for all patients with an HM, universal germline testing for allogeneic haematopoietic stem cell donors, and the development of preventive strategies to delay or even prevent malignancies will be available in the near future. These factors will likely contribute to improved health outcomes for at-risk individuals and their family members.

Inherited predisposition to haematopoietic malignancies: overcoming barriers and exploring opportunities

Inherited predisposition to haematopoietic malignancies, due to deleterious germline variants in a variety of genes, is an important clinical entity with implications for the health and management of patients and their family members. Unfortunately, there remain several common misconceptions in this field that can result in patients going unrecognised and/or having incomplete or improper testing including: the impression that inherited haematological malignancy syndromes are rare, that myeloid and lymphoid malignancy predisposition syndromes are mutually exclusive, and that solid tumour predisposition syndromes are unique and distinct from haematopoietic malignancy predisposition syndromes. In the present review, we challenge these ideas with our insights into germline genetic testing for these conditions with the hope that increased awareness and knowledge will overcome barriers and lead to improved diagnosis and management.

Identifying potential germline variants from sequencing hematopoietic malignancies

Next-generation sequencing (NGS) of bone marrow and peripheral blood increasingly guides clinical care in hematological malignancies. NGS data may help to identify single nucleotide variants, insertions/deletions, copy number variations, and translocations at a single time point, and repeated NGS testing allows tracking of dynamic changes in variants during the course of a patient's disease. Tumor cells used for NGS may contain germline, somatic, and clonal hematopoietic DNA alterations, and distinguishing the etiology of a variant may be challenging. We describe an approach using patient history, individual variant characteristics, and sequential NGS assays to identify potential germline variants. Our current criteria for identifying an individual likely to have a deleterious germline variant include a strong family history or multiple cancers in a single patient, diagnosis of a hematopoietic malignancy at a younger age than seen in the general population, variant allele frequency > 0.3 of a deleterious allele in a known germline predisposition gene, and variant persistence identified on clinical NGS panels, despite a change in disease state. Sequential molecular testing of hematopoietic specimens may provide insight into disease pathology, impact patient and family members' care, and potentially identify new cancer-predisposing risk alleles. Ideally, individuals should give consent at the time of NGS testing to receive information about potential germline variants and to allow future contact as research advances.