The clinical and laboratory evaluation of patients with suspected hypocellular marrow failure

The overlap in clinical presentation and bone marrow features of acquired and inherited causes of hypocellular marrow failure poses a significant diagnostic challenge in real case scenarios, particularly in nonsevere disease. The distinction between acquired aplastic anemia (aAA), hypocellular myelodysplastic syndrome (MDS), and inherited bone marrow failure syndromes presenting with marrow hypocellularity is critical to inform appropriate care. Here, we review the workup of hypocellular marrow failure in adolescents through adults. Given the limitations of relying on clinical stigmata or family history to identify patients with inherited etiologies, we outline a diagnostic approach incorporating comprehensive genetic testing in patients with hypocellular marrow failure that does not require immediate therapy and thus allows time to complete the evaluation. We also review the clinical utility of marrow array to detect acquired 6p copy number-neutral loss of heterozygosity to support a diagnosis of aAA, the complexities of telomere length testing in patients with aAA, short telomere syndromes, and other inherited bone marrow failure syndromes, as well as the limitations of somatic mutation testing for mutations in myeloid malignancy genes for discriminating between the various diagnostic possibilities.

Impaired myelopoiesis in congenital neutropenia: insights into clonal and malignant hematopoiesis

A common feature of both congenital and acquired forms of bone marrow failure is an increased risk of developing acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Indeed, the development of MDS or AML is now the major cause of mortality in patients with congenital neutropenia. Thus, there is a pressing clinical need to develop better strategies to prevent, diagnose early, and treat MDS/AML in patients with congenital neutropenia and other bone marrow failure syndromes. Here, we discuss recent data characterizing clonal hematopoiesis and progression to myeloid malignancy in congenital neutropenia, focusing on severe congenital neutropenia (SCN) and Shwachman-Diamond syndrome. We summarize recent studies showing excellent outcomes after allogenic hematopoietic stem cell transplantation for many (but not all) patients with congenital neutropenia, including patients with SCN with active myeloid malignancy who underwent transplantation. Finally, we discuss how these new data inform the current clinical management of patients with congenital neutropenia.

Mechanisms of somatic transformation in inherited bone marrow failure syndromes

Inherited bone marrow failure syndromes (IBMFS) cause hematopoietic stem progenitor cell (HSPC) failure due to germline mutations. Germline mutations influence the number and fitness of HSPC by various mechanisms, for example, abnormal ribosome biogenesis in Shwachman-Diamond syndrome and Diamond-Blackfan anemia, unresolved DNA cross-links in Fanconi anemia, neutrophil maturation arrest in severe congenital neutropenia, and telomere shortening in short telomere syndrome. To compensate for HSPC attrition, HSPCs are under increased replication stress to meet the need for mature blood cells. Somatic alterations that provide full or partial recovery of functional deficit implicated in IBMFS can confer a growth advantage. This review discusses results of recent genomic studies and illustrates our new understanding of mechanisms of clonal evolution in IBMFS.

Brazilian Consensus Meeting on Pediatric Hematopoietic Stem Cell Transplantation for Acquired Aplastic Anemia and Inherited Bone Marrow Failure Syndromes

THE BRAZILIAN SOCIETY FOR BLOOD AND MARROW TRANSPLANTATION (SBTMO) PRESENTS THE BRAZILIAN GUIDELINES ON HEMATOPOIETIC STEM CELL TRANSPLANTATION FOR ACQUIRED APLASTIC ANEMIA AND INHERITED BONE MARROW FAILURE SYNDROMES

Clinical Significance of Small PNH-Type Cell Populations in Bone Marrow Failure Syndromes - an Interim Analysis of Japanese Multicentrer Prospective Study -

Background: Small populations of paroxysmal nocturnal hemoglobinuria (PNH)-type cells (<1.0%) are frequently found in bone marrow failure syndromes (BMF) including aplastic anemia (AA) and low-risk myelodysplastic syndromes (MDS) without evident hemolytic symptoms. The presence of small PNH-type cells has been reported to predict better response to immunosuppressive therapy (IST) both retrospectively (Blood 2006 107:1308-1314) and prospectively (Br J Haematol 2014 164:546-54), but its clinical significance is still to be elucidated. In addition, the kinetics of those small PNH-type cells have not been well studied. To better understand the clinical significance and the kinetics of PNH-type cells in BMF, we conducted a nationwide, multicenter, prospective, observational clinical study named SUPREMACY. Methods: Patients diagnosed with PNH, AA, MDS or indistinguishable BMF without malignant diseases were prospectively recruited to the study between April 1 st, 2016 and December 31 st, 2019 in Japan. Participants were excluded from the study if treated with eculizumab or ravulizumab. Peripheral blood samples were obtained with informed consent and sent to the single laboratory every 12months (mos) for 36 mos. A high-resolution flow cytometry assay known as OPTIMA method (Ann Hematol 97(12):2289-2297) was used to precisely detect a small population of GPI(-) cells, which defines ≥0.003% PNH-type granulocytes (Gran) and ≥0.005% erythrocytes as an abnormal increase. The quality of life (QOL) of the pts was assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) instruments. All other lab data and clinical information were obtained at each participating institute or hospital on sample collection, and were accumulated by the Japan PNH Study Group for analysis. Results: Total 1,985 pts were registered and 1,813 pts were eligible for analysis. Median age was 67 with 50.5% male patients. PNH-type cells were positive in 50.4% (235/466) of AA, 19.7% (70/355) of MDS, 22.3% (61/273) of suspected PNH, and 33.9% (232/685) of undiagnosed BMF. PNH-type cells were increased in nearly 30% of the pts with RCUD, RCMD, MDS-U, and 5q-, but not in RARS, RAEB-1, or RAEB-2. Time-course data of the size of PNH-type cells were available in 651 pts at 12mos and in 210 pts at 36mos. Small (<1.0%) PNH-type granulocytes (sPNHg) stayed below 1.0% at 36mos in 81/86 (94.2%) pts, but increased in 5/86 (5.8%) by median 2.75% or by average 17.86% at 36mos. Clinical data for IST were available in 277 pts (12mos) and 99 pts (36mos). Pts with PNH-type cells showed a better response rate [Complete response (CR) + Partial response (PR), 159/201 (79.1%) at 12mo, 68/73 (93.2%) at 36mo] to IST compared to the pts without PNH-type cells [48/76 (63.2%) at 12mos, 17/26 (65.4%) at 36mos] (P<0.01, Chi-square test)(Figure 1). Changes of QOL data were compared between the pts with sPNHg [PNH(+)] and the pts without PNH-type cells [PNH(-)] at 36mos, and PNH(+) showed significant improvement in FACIT-Fatigue score (n=36, p=0.0348, Chi-square test) and in 6 items of EORTC QLQ-C30 (global health status, emotional functioning, social functioning, fatigue, and financial difficulties)(n=40) but no significant change of QOL was observed except in one item (constipation) in PNH(-) (n=36)(Table 1). Conclusion: PNH-type cells were detected exclusively in AA and low-risk MDS, supporting the hypothesis that the increase of PNH-type cells in BMF underpin the benign immune-mediated feature of the disease. The presence of PNH-type cells predicts a better response to IST in BMF, which is consistent with previous reports. Detection of subclinical PNH-type cells was associated with an improvement of QOL scores in multiple items at 36mos. Those small populations of PNH-type cells stayed subclinical in most of the cases, but caution should be exercised in monitoring the sizes as some may evolve into clinical PNH. Figure 1 Figure 1. Disclosures Ueda: Chugai Pharmaceutical: Consultancy, Honoraria, Research Funding; Alexion Pharma: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Yonemura: Alexion Pharma: Honoraria, Research Funding; Chugai Pharmaceutical: Research Funding; Novartis Pharma: Honoraria. Obara: Novartis Pharma: Honoraria; Chugai Pharmaceutical: Honoraria, Research Funding; Alexion Pharma: Honoraria, Research Funding. Ando: Novartis: Honoraria; Kyowa Kirin: Research Funding; Chugai Pharmaceutical: Research Funding; Celgene: Honoraria; Astellas Pharma: Honoraria; Takeda Pharmaceutical: Research Funding. Kawaguchi: Alexion Pharma: Honoraria. Nishimura: Alexion Pharma: Consultancy; Chugai Pharmaceutical: Consultancy; Novartis Pharma: Consultancy; Roche: Consultancy; apellis pharmaceuticals: Consultancy; Biocryst: Consultancy; Sanofi: Consultancy. Nakao: Kyowa Kirin: Honoraria; Novartis Pharma: Honoraria; Symbio: Consultancy; Alexion Pharma: Research Funding.

Genomic-Based Machine Learning Towards Prediction of the Etiology of Bone Marrow Failure Syndromes

Genetic testing has been increasingly used to assist with differential diagnosis of acquired vs inherited bone marrow failure syndromes (IBMFS), a group of rare and heterogeneous diseases. However, the assay is still costly and not routinely available for many hematologists. To improve decision-making for genetic testing, we developed a genomic-based machine-learning model based on a two-step data-driven clustering and classification process to predict the likelihood of BMF patients having either an acquired or inherited disease based on 27 clinical and laboratory variables recorded at initial clinical encounter. Clinical records from two independent cohorts of patients screened for pathogenic variants in genes associated with IBMFS were included in this study: the NIH cohort with 441 consecutive patients followed at the NHLBI and NCI, and the USP cohort with 172 consecutive patients from the Medical School of Ribeirão Preto/USP. In a binary target classification, cases were labeled as inherited if they had a pathogenic/likely pathogenic disease-causing variant and as acquired when they had benign or likely benign variants or negative genetic test, regardless of patients' clinical diagnoses. K-means clustering was first applied to resolve our highly dimensional data into two main clusters (Clusters A and B). An optimized bootstrap aggregation ensemble Cluster A specific was trained with cases from the NIH cohort (n=359). The model was then validated with Cluster A cases from the external USP cohort (n=127). The binary classification task was utilized to predict the etiology of BMF cases, labeled as acquired or inherited depending on patients' genomic data. At first, unsupervised clustering separately grouped datasets into Cluster A, the largest group mostly represented by aplastic anemia (AA), and Cluster B, those underrepresented in our cohort including some classical IBMFS at early disease onset. The ensemble model Cluster A-specific was accurate to predict the BMF etiology in 88% of cases, correctly predicting inherited and likely immune BMF in 72% and 92% of cases, respectively. Out of the 27 initial clinical variables included in the model, 25 were found to be important for prediction. Telomere length (TL), age, and clinical variables were most important for the model's predictive accuracy, highlighting that a comprehensive history and physical examination encompassing all organ systems is imperative. Based on our model, genetic testing must be considered for patients in Cluster A predicted to have inherited disease and also for patients in Cluster B as no specific model was available but they were more likely to have IBMFS in comparison to Cluster A (50% vs 30%). We also recommend genetic screening in patients from Cluster A predicted to have acquired disease who are children (age <18 years who may not have clinical signs of IBMFS), have consanguinity in the family, have a diagnosis of myelodysplastic syndromes with or without suspicion for familial predisposition to myeloid malignancies (all cases where the model had limited prediction). A model without TL, an assay that can also be limited in low-resource centers, underperformed for prediction of inherited cases with sensitivity of 55%, highlighting the importance of TL measurement for the model's performance. Our machine-learning model reproduced the clinical knowledge used by clinicians specialized in BMF and accurately predicted BMF etiology in 88% of cases. The model was particularly accurate for differential diagnosis of immune AA in adults, which may allow for selections of patients in whom rapidly starting immunosuppression rather than waiting weeks for genetic results is preferable. Clinical variables were strong predictors and adult patients with severe AA rarely had an inherited disease without a positive family history, a suggestive phenotype of IBMFS, or consanguinity being present. The generalizability of our model indicates that this tool can be used by hematologists not specialized in BMF to prioritize patients that would benefit from genetic testing. TL was a top predictor and a key variable for this model's accuracy. Implementation of TL measurement may be critical for differential diagnosis of BMF, especially in low-resource centers where genetic testing is not feasible or readily available. We plan to continue adding to the model to better predict IBMFS cases that were underrepresented in the current cohort. Disclosures Calado: Instituto Butantan: Consultancy; Agios: Membership on an entity's Board of Directors or advisory committees; Alexion Brasil: Consultancy; Novartis Brasil: Honoraria; Team Telomere, Inc.: Membership on an entity's Board of Directors or advisory committees; AA&MDS International Foundation: Research Funding. Young: Novartis: Research Funding.

TGFβ signaling modifies hematopoietic acute inflammatory response to drive bone marrow failure

Bone marrow failure syndromes (BMF) are characterized by ineffective hematopoiesis due to impaired fitness of hematopoietic stem cells (HSC). BMFs can be acquired during bone marrow stress or innate are associated with driver genetic mutations. BMFs are at higher risks of developing secondary neoplasms, including myelodysplastic syndromes and leukemia. Despite the identification of genetic driver mutations, the hematopoietic presentation of the disease is quite heterogeneous raising the possibility that non-genetic factors contribute to the pathogenesis of the disease. The role of inflammation has emerged as an important contributing factors, but remain to be understood in detail. In this study, we examined the effect of increased TGFβ signaling in combination or not with an acute innate immune challenge using polyinosinc:polycytidilic acid (pIC) on the hematopoietic system without genetic mutations. We show that acute rounds of pIC alone drive a benign age-related myeloid cell expansion, increased TGFβ signaling alone causes a modest anemia on old mice. In sharp contrast, increased TGFβ signaling plus acute pIC challenge result in chronic pancytopenia, expanded hematopoietic stem and progenitor pools, and increased bone marrow dysplasia 3-4 months after stress, phenotypes similar to human bone marrow failure syndromes. Mechanistically, this disease phenotype is uniquely associated with increased mitochondrial content, increased reactive oxygen species and enhanced caspase-1 activity. Our results suggest that chronic increased TGFβ signaling modifies the memory of an acute immune response to drive bone marrow failure without the need for pre-existing genetic insult. Hence, non-genetic factors in combination are sufficient to drive bone marrow failure.

Pulmonary Complications After Pediatric Stem Cell Transplant

The number of disorders that benefit from hematopoietic stem cell transplantation (HSCT) has increased, causing the overall number of HSCT to increase accordingly. Disorders treated by HSCT include malignancy, benign hematologic disorders, bone marrow failure syndromes, and certain genetic diagnoses. Thus, understanding the complications, diagnostic workup of complications, and subsequent treatments has become increasingly important. One such category of complications includes the pulmonary system. While the overall incidence of pulmonary complications has decreased, the morbidity and mortality of these complications remain high. Therefore, having a clear differential diagnosis and diagnostic workup is imperative. Pulmonary complications can be subdivided by time of onset and whether the complication is infectious or non-infectious. While most infectious complications have clear diagnostic criteria and treatment courses, the non-infectious complications are more varied and not always well understood. This review article discusses pulmonary complications of HSCT recipients and outlines current knowledge, gaps in knowledge, and current treatment of each complication. This article includes some adult studies, as there is a significant paucity of pediatric data.