Diagnosis Of Aplastic Anemia Research Articles

Monitoring and Treatment of Paroxysmal Nocturnal Hemoglobinuria in Patients with Aplastic Anemia in Asia: An Expert Consensus.

Paroxysmal nocturnal hemoglobinuria (PNH) clones can be identified in a significant proportion of patients with aplastic anemia (AA). Screening for PNH clones at the time of an AA diagnosis is recommended by national and international guidelines. In this report, an expert panel of physicians discusses current best practices and provides recommendations for managing PNH in patients with AA in the Asia-Pacific region. Plasma/serum lactate dehydrogenase (LDH) levels and reticulocyte count should be measured with every blood test. PNH clone size should be monitored regularly by flow cytometry, with on-demand testing in the event of a rise in LDH level ± reticulocyte count or development of symptoms such as thrombosis. Monitoring for PNH clones can guide the choice of initial AA treatment, although flow cytometry has resource implications which may present a challenge in some Asia-Pacific countries. The treatment of patients with both PNH and AA depends on which condition predominates; following PNH treatment guidelines if hemolysis is the main symptom and AA treatment guidelines if bone marrow failure is severe (regardless of whether hemolysis is mild or moderate). The expert panel's recommendations on the monitoring and treatment of PNH in patients with AA are practical for healthcare systems in the Asia-Pacific region.

Maternal and Fetal Outcomes of Aplastic Anemia During Pregnancy and Delivery: Systematic Review and Meta-Analysis.

Little scientific evidence exists on maternal and fetal outcomes in aplastic anemia (AA) during pregnancy. The review was conducted to assess the maternal and fetal outcomes due to AA during pregnancy. Web of Science, EMBASE, PubMed, Scopus, Cochrane CENTRAL, and registries until May 5, 2024. Studies (prospective, retrospective cohort, cross-sectional, one arm, survey, follow-up studies) evaluating AA during pregnancy were searched as per PROSPERO registered protocol (CRD42024506668). Case reports, case series, expert opinion letters, and studies assessing less than or equal to 10 pregnant women were not considered. The primary outcome was the prevalence of preeclampsia in AA pregnancies. The secondary outcomes included spontaneous abortion, preterm premature rupture of membranes, premature rupture of membranes, fetal growth restriction, type of delivery, intrauterine fetal death, maternal and neonatal mortality, and pre and post-pregnancy remission status comparison. The quality of research was checked using the New Castle-Ottawa risk-of-bias tool. A meta-analysis model with a random effect distribution, coupled with meta-regression, sensitivity analysis, and publication bias assessment, was used in the statistical software R. Standard Equator network study reporting guidelines were followed. Seven (one prospective and six retrospective cohort) studies included patients with confirmed AA diagnosis in 248 pregnancies. The pooled prevalence of preeclampsia was 13% (95% CI, 8%-20%). Heterogeneity was low in the present meta-analysis (I2 = 26%). The secondary outcome evaluation showed a pooled prevalence of 5% (95% CI, 3%-11%) for spontaneous abortion, 4% (95% CI, 1%-11%) for preterm premature rupture of membranes, 10% (95% CI, 3%-28%) for premature rupture of membranes, 6% (95% CI, 3%-11%) for fetal growth restriction, 5% (95% CI, 2%-13%) for intrauterine fetal death, 12% (95% CI, 5%-26%) for post-partum hemorrhage, 74% (95% CI, 45%-91%) for intrapartum transfusion requirement, and 55% (95% CI, 27%-80%) for the cesarean delivery opting. The maternal mortality in pregnancies with AA was 4% (95% CI, 0.01-0.14), whereas neonatal mortality was 7% (95% CI, 0.03-0.18). The odds of AA complete remission were better in pre-pregnancy than post-pregnancy (OR = 0.36; 95% CI = 0.08-1.66), although the results remain insignificant. The leave-one-out sensitivity analysis did not change the pooled estimates for the primary outcome. A risk of developing preeclampsia was observed in every eighth pregnant woman with an AA diagnosis. AA remission status might worsen after undergoing pregnancy, considering the significant obstetric morbidity and mortality burden.

Proton Density Fat Fraction Quantification (PD-FFQ): Capability for hematopoietic ability assessment and aplastic anemaia diagnosis of adults

PurposeThe purpose of this study was to determine the capability of proton density with fat fraction (PD-FFQ) imaging to help assess hematopoietic ability and diagnose aplastic anemia in adults. MethodsBetween January 2021 and March 2023, patients diagnosed with aplastic anemia (AA: n = 14) or myelodysplastic syndrome (MDS: n = 14) were examined by whole-body PD-FFQ imaging, and 14 of 126 age and gender matched patients who had undergone the same PD-FFQ imaging were selected as control group. All proton density fat fraction (PDFF) index evaluations were then performed by using regions of interest (ROIs). Pearson's correlation was used to determine the relationship between blood test results and each quantitative index, and ROC-based positive test and discrimination analyses to compare capability to differentiate the AA from the non-AA group. Finally, sensitivity, specificity and accuracy of all quantitative indexes were compared by means of McNemar's test. ResultsMean PDFF, standard deviation (SD) and percentage of coefficient of variation (%CV) for vertebrae showed significant correlation with blood test results (−0.52 ≤ r ≤ −0.34, p < 0.05). Specificity (SP) and accuracy (AC) of %CV of PDFF in vertebrae were significantly higher than those of mean PDFF in vertebrae and the posterior superior iliac spine (SP: p = 0.0002, AC: p = 0.0001) and SD of PDFF in vertebrae (SP: p = 0.008, AC: p = 0.008). Moreover, AC of SD of PDFF in vertebrae was significantly higher than that of mean PDFF in vertebrae and the posterior superior iliac spine (p = 0.03). ConclusionWhole-body PD-FFQ imaging is useful for hematopoietic ability assessment and diagnosis of aplastic anemia in adults.

The ratio of bone marrow myeloid progenitor cell proportion to mature lymphocytes proportion can effectively differentiate aplastic anemia and hypoplastic myelodysplastic syndrome and evaluate the quality of bone marrow aspirates.

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (MDS-h) are bone marrow failure disease and difficult to distinguish merely by morphological analysis. In this study, we investigated the value of flow cytometry (FCM) in the differential diagnosis of AA and MDS-h. We included 822 patients (626 control, 69 AA, 22 MDS-h and 105 dilution patients) from January 2017 to December 2022 for a retrospective study. Bone marrow myeloid progenitor (MP) cell and mature lymphocytes proportions were analyzed by FCM. The ratio of MP cell proportion and mature lymphocytes proportion, MPLR, was calculated. Data were compared by Kruskal-Wallis test. Differential diagnostic efficacy was evaluated by receiver operating characteristic (ROC) curve. Cutoff value was determined by the maximum Youden index. Bone marrow MP cell proportion and MPLR of MDS-h patients were higher than AA patients. Mature lymphocytes proportion of MDS-h patients was lower than AA patients. Area under ROC curve (AUC of ROC) of MP cell proportion, MPLR and mature lymphocytes proportion to distinguish AA from MDS-h were 0.992, 0.988, and 0.850, respectively. Moreover, MPLR of dilution patients was higher than AA patients but lower than MDS-h patients. The AUC of ROC curves of MPLR to distinguish MDS-h and AA from dilution were 0.854 and 0.871, respectively. Bone marrow MP cell proportion and MPLR can effectively discriminate AA from MDS-h with similar differential efficacy, which is higher than mature lymphocytes proportion. Moreover, MPLR can evaluate the quality of bone marrow aspirates, which would interfere with the differential diagnosis.

Diagnostic evaluation in bone marrow failure disorders: what have we learnt to help inform the transplant decision in 2024 and beyond?

Aplastic anemia (AA) is the prototypical bone marrow failure syndrome. In the current era of readily available 'molecular annotation', application of comprehensive next-generation sequencing panels has generated novel insights into underlying pathogenetic mechanisms, potentially leading to improvements in personalized therapeutic approaches. New evidence has emerged as to the role of somatic loss of HLA class I allele expression in 'immune-mediated' AA, associated molecular aberrations, and risk of clonal evolution. A deeper understanding has emerged regarding the role of 'myeloid' gene mutations in this context, translating patho-mechanistic insights derived from wider clinical and translational research within the myeloid disorder arena. Here, we review contemporary 'tools' which aid in confirmation of a diagnosis of AA, with an additional focus on their potential in guiding therapeutic options. A specific emphasis is placed upon interpretation and integration of this detailed diagnostic information and how this may inform optimal transplantation strategies.

Quantitative Dixon and intravoxel incoherent motion diffusion magnetic resonance imaging parameters in lumbar vertebrae for differentiating aplastic anemia and acute myeloid leukemia.

We sought to evaluate the use of quantitative Dixon (Q-Dixon) and intravoxel incoherent motion diffusion imaging (IVIM) for the differential diagnosis of aplastic anemia (AA) and acute myeloid leukemia (AML). Between August 2021 and October 2023, we enrolled 68 diagnosed patients, including 36 patients with AA and 32 patients with AML, as well as 26 normal controls. All patients underwent 3-Tesla magnetic resonance imaging, which included IVIM and T2*-corrected Q-Dixon imaging at the L2-4 level. The iliac crest biopsy's pathology was used as the diagnostic criterion. The interobserver measurement repeatability was evaluated using the intraclass correlation coefficient (ICC). One-way analysis of variance, Spearman analysis, and receiver operating characteristic curve analysis were used. The fat fraction (FF) and perfusion fraction (f) values were statistically significantly different between the three groups (p < 0.001 and p = 0.007). The FF and f values in the AA group were higher than those in the AML group. The true apparent diffusion coefficient (D) value was substantially negatively correlated to the FF and R2* values (r = -0.601, p < 0.001; r = -0.336, p = 0.002). The f value was positively correlated with both FF and pseudo-apparent diffusion coefficient (D*) values (r = 0.376, p < 0.001; r = 0.263, p = 0.017) and negatively correlated with the D value (r = -0.320, p = 0.003). The FF and f values were negatively correlated with the degree of myelodysplasia (r = -0.597, p < 0.001; r = -0.454, p = 0.004), and the D value was positively correlated with the degree of myelodysplasia (r = 0.395, p = 0.001). For the differential diagnosis of AA and AML, the Q-Dixon model's sensitivity (93.75%) and specificity (84%) confirmed that it outperformed the IVIM model. Q-Dixon parameters have the potential to be used as new biomarkers to differentiate AA from AML.

Predicting Clonal Evolution to Secondary Myeloid Neoplasms in Aplastic Anemia through Machine Learning

Background: One of the major long-term complications in aplastic anemia (AA) is the clonal evolution to secondary myeloid neoplasms (sMNs) such as acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) 1. Hematopoietic stem cell transplantation (HSCT) is largely considered a curative treatment option for AA and is effective at preventing the clonal evolution of sMNs 2. However, patients over 40 years old or those with poor donor options are contraindicated for HSCT due to elevated post-transplant mortality rates 3. When treated with non-transplant strategies, patients with AA have indeed a high risk for acquisition/expansion of somatic myeloid mutations, with some harbingers of future clonal progression to full-blown MDS or AML. Older age, presence of myeloid mutations other than BCOR/L and PIGA at onset, and lack of response to standard immunosuppressive treatment (IST) have been identified as factors predictive for subsequent sMN evolution 4,5,6. If an individual patient's risk of developing a sMN could be assessed through a predictive model that uses information collected at initial AA diagnosis, providers may consider HSCT for traditionally contraindicated patients. However, no such predictive model that could aid in risk assessment currently exists. Methods: In our study, we utilized a large, multi-institutional cohort of patients diagnosed with AA to generate a comprehensive dataset. This dataset contained 76 variables, encompassing relevant clinical and molecular annotations. On this dataset, we trained a machine learning (ML) model to predict patients who would evolve sMNs. Variables with the highest feature impact score (FIS) in predicting clonal evolution to sMN were then chosen to be included in the final ML model, and the algorithm's fitness was calculated using the Leave-One-Out cross-validation method. Variables missing in more than 30% of subjects were imputed using K-Nearest Neighbors (N=20). Of our initial cohort of 455 patients, 213 patients were excluded from the study. 35 patients were excluded because they were treated with HSCT. 39 pediatric cases (defined as &amp;lt;18 years old at the time of diagnosis) were excluded from the study. 91 patients were removed for not receiving specific treatment (IST or HSCT). The remaining 77 patients were excluded due to having a sMN detected at the time of or prior to AA diagnosis, insufficient data, or detection of a germline mutation indicative of an inherited pathophysiology. Our final cohort included a total of 242 acquired AA patients from UT Southwestern Medical Center and Cleveland Clinic. Results: Among our final cohort of 242 patients, 119 (49.2%) were male. The cohort's mean and median ages at AA diagnosis were 53.1 years (SD = 18.9 years) and 58.1 years, respectively. The median follow-up time was 4.04 years. 80 (33.1%) of our patients had a clinically significant PNH clone (defined as &amp;gt;0.001%). 29 patients developed sMNs, with 24 developing MDS and 5 developing AML. Of patients who underwent clonal evolution to sMNs, the median age at the time of AA diagnosis and sMN diagnosis was 63.1 years and 67.2 years, respectively. The median time elapsed from initial AA diagnosis to sMN evolution was 3.78 years. The median time elapsed between initial AA diagnosis and earliest IST administration was 51 days. Chi-squared analysis showed that patients who received ATG treatment were more likely to develop sMNs, with 78.0% of all patients receiving ATG, while 96.6% of patients who developed sMNs had received ATG (p=0.00927). Our ML model achieved a sensitivity of 0.759, a specificity of 0.728, and an AUC of 0.78 using the ten variables with the highest feature impact score (FIS) to predict clonal evolution [Table 1]. All of the variables except for the presence of a PNH clone are positively correlated with sMN evolution. Nine of these variables are supported by existing literature 7,8. The feature with the third highest feature impact score, the time elapsed (days) between diagnosis and IST treatment, has not been established by previous studies and may be an important consideration in establishing optimal AA treatment guidelines. Conclusion: The strategic combination of this ML algorithm with clinical expertise has tremendous potential in improving health outcomes. Identification of patients at high risk for sMN and offering HSCT as a curative option upfront may lead to improved overall survival in AA patients.

Insights from Trajectories of PIGA-Mutated Clones in Paroxysmal Nocturnal Hemoglobinuria

Background: Patients with paroxysmal nocturnal hemoglobinuria (PNH) exhibit clonal expansion of hematopoietic cells deficient in glycosylphosphatidylinositol-anchored proteins (GPI-APs). Mutations in PIGA gene, involved in the biosynthesis of GPI-APs, result in the loss of GPI-APs from hematopoietic cells. However, PIGA mutations alone are insufficient to drive this clonal expansion. The pathogenesis of clonal expansion in PNH remains elusive, while several hypotheses or factors have been proposed, including immune attacks with concomitant aplastic anemia (AA) or additional mutations offering intrinsic growth advantage. Recently high-sensitivity flow cytometry and next-generation sequencing have allowed us to evaluate the clonal dynamics and architecture more precisely. The method has the potential to clarify the trajectories of PIGA mutated clones before the significant clonal expansion or the diagnosis, thereby to gain insight into the pathogenesis of the clonal expansion in PNH. Methods: To estimate the trajectories of PIGA-mutated clones, we constructed phylogenetic trees using whole genome sequencing (WGS) data of single cell-derived colonies of bone marrow samples from two PNH patients (53 colonies for Case 1 and 75 for Case 2). We used the targeted-sequencing and exome sequencing to detect driver mutations after isolating GPI-deficient and GPI-positive cells using flow cytometry. Results: Case 1 was diagnosed with AA at the age of 28. He developed hemoglobinuria at the age of 40 and was diagnosed with PNH at the age of 45. Bone marrow and peripheral blood samples were collected when he was 47 years old. The PNH clone sizes in granulocytes and red blood cells were 88.7% and 46.1%, respectively. Targeted-sequencing revealed six PIGA mutations in GPI-deficient cells and three BCOR mutations in GPI-positive cells. Case 2 was diagnosed with AA at the age of 33 and with PNH at the age of 34. Bone marrow and peripheral blood samples were collected when she was 59 years old. The PNH clone sizes in granulocytes and red blood cells were 98.6% and 96.3%, respectively. We previously identified chromosomal abnormalities in chr12, with the breakpoint located in an HMGA2 gene (Inoue et al. Blood. 2006). Targeted-sequencing detected no other driver mutations than single PIGA mutation and the HMGA2 mutation.In Case 1, Phylogenetic tree analysis constructed with WGS of single cell-derived colonies revealed multiple PIGA-mutated and BCOR-mutated clones that expanded independently of each other. All BCOR-mutated clones were identified in the GPI-positive population. In Case 2, all PIGA-mutated clones harbored the HMGA2 mutation, while no GPI-positive populations acquired the HMGA2 mutation.In both cases, the numbers of passenger single nucleotide variants per year were higher in PIGA-mutated clones than in PIGA-unmutated clones (16 vs. 11 mutations/year for Case 1 and 14 vs. 12 for Case 2). Assuming that variant acquisition rates per cell division are similar in both clones, the result suggests that PIGA-mutated clones had growth advantage against PIGA-unmutated clones.The acquisition of PIGA mutations was estimated to have occurred more than ten years prior to the PNH diagnosis. In Case 1, following the AA diagnosis, both PIGA-mutated clones and BCOR-mutated clones started expansion simultaneously, which suggests an association with immune attacks. Interestingly, even wild type clones expanded after AA diagnosis, suggesting bottle-neck effects of post-AA hematopoietic recovery. In Case 2, PIGA-mutated clones began expanding more than ten years before the AA diagnosis. Either a subclinical immune attack that might have existed before the diagnosis of clinical AA or the concomitant HMGA2 mutation conferred survival advantage for PIGA-mutated clones in Case 2. Conclusions: This estimation of the trajectories of the PIGA-mutated clone indicates that the pathogenesis of clonal expansion exhibits heterogeneity between two PNH patients.

Aplastic Anemia: Insight from a Single Center Experience

CONTEXT: Aplastic anemia (AA) is a rare disease with changing treatment modalities over time. Patients often do not respond to first line therapy and require multiple lines of therapy. Treatment has also evolved over time, with the addition of thrombopoietin receptor agonists. Understanding treatment response and outcomes remains imperative. AIMS: To categorize treatments and outcomes of aplastic anemia patients DESIGN: Single center retrospective study of 96 patients who were seen at Moffitt Cancer Center with a diagnosis of Aplastic Anemia between January 2009 and January 2023. RESULTS: Our study included 96 patients (mean age at diagnosis, 54 years) diagnosed with AA. 56 patients (58%) were male, while 41 patients (42%) were female. Seventy-four (74%) were Caucasian, 7 (7%) were African American, 10 (10%) were Hispanic. At diagnosis, mean white blood count was 2.60, with an absolute neutrophil count of 1.02, a hemoglobin of 8.45, and platelet count of 26. At diagnosis, 67/91 (70%) patients had required packed red blood cell transfusion, while 68/91 (71%) had required platelet transfusion. In total, 77/91 (80%) required either a packed red blood cell or platelet transfusion at the time of diagnosis. At diagnosis, 27 patients had infectious complications while 27 also had bleeding complications. Bone marrow cellularity was 10% or less in 59/86 patients (69%), and under 15% in 71 (83%). Forty-two patients were tested for large granular lymphocyte (LGL) clones, and 14 (33%) had clones present. Paroxysmal nocturnal hematuria (PNH) clones were detected in 35 out of the 75 patients tested (47%). The clones progressed in 14 patients. Seven patients had transformation from AA into Myelodysplastic syndrome (MDS), while 3 had transformation into Acute Myeloid Leukemia (AML). Of the 96 patients, 6 patients were managed with observation. The most used frontline therapies were equine ATG (eATG) + cyclosporine (CSA) in 41 patients, followed by eATG + CSA + eltrombopag in 20 patients. In total, 65 patients received eATG based therapy first line (4 patients received eATG alone frontline). Eleven patients received an eltrombopag based therapy without concomitant ATG. Between singlet/doublet eATG based therapy and triplet therapy, the overall response rate to singlet/doublet was 66% (complete response rate (CR) 23%, partial response rate (PR) 43%) and 67% for triplet (CR 28%, PR 39%) (p=.91). There was no difference to date in OS. There was also no difference in response based on the presence on PNH clones or LGL clones. When looking specifically at severe/very severe AA, triplet CR was 30%, while singlet/doublet was 19%, showing a higher trend of CR in those patients receiving triplet therapy and severe/very severe AA. Thirty-eight patients who received eATG based singlet/doublet or triplet therapy upfront also received a second line treatment. The most common treatments were eltrombopag in 8 and Allogenic Hematopoietic Stem Cell Transplant (AHSCT) in 7. Fifteen had no response, 13 had a partial response, and 10 had complete response. Three patients received AHSCT as a first line therapy, while another 19 patients received it second line or greater. AHSCT was second line for 10 patients, third line for 5, and fourth line for 3. Of these 22 patients, 2 had documented relapse (after receiving it as second line therapy) and were retransplanted. One developed MDS after AHSCT. CONCLUSIONS: AA is diagnosed primarily in symptomatic patients requiring transfusions with life threatening cytopenias. Frontline treatment varies, but the most common therapies, which rely on eATG and CSA, as well as more recently thrombopoietin receptor agonists, have shown the most success. Our data showed that triplet therapy, incorporating eATG, CSA, and eltrombopag had a similar overall response rate, but that CR was higher in patients with severe/very severe AA receiving triplet versus singlet/doublet therapy upfront. Patients often require multiple lines of treatment. AHSCT remains a viable treatment option, with great response, but is not without its drawbacks.

Aplastic Anemia Patients Have Diverse T Cell Repertoires and Flexible T Cell Responses Similar to Healthy Individuals

Acquired aplastic anemia (AA) is a bone marrow failure disease caused by T cell-mediated autoimmune attack on hematopoietic stem and progenitor cells (HSPCs). Identifying autoreactive T cells in AA has been challenging. Advances in T cell receptor (TCR) sequencing and the discovery of Human Leukocyte Antigen Class I (HLA-I) risk alleles linked to autoantigen presentation in AA have rekindled interest in exploring T cell repertoires in AA. We hypothesized that autoreactive CD8 + T cells in AA may have convergent TCR structures allowing them to recognize AA autoantigens presented by specific HLA-I risk alleles. To test our hypothesis, we analyzed TCR repertoires and HLA-restricted CD8 + T cell reactivity in AA patients. Using TCR Vβ (TRB) sequencing, we analyzed 83 patient samples obtained at AA diagnosis or relapse. High-risk alleles HLA-B*14:02 and B*40:02 were present in 26% and 10% of patients, respectively. HLA-DR*15 was present in 24%. Patient samples were largely sorted bone marrow (BM) CD8 + T lymphocytes. Patient TRB repertoires were compared to those in 709 control samples, largely of unsorted peripheral blood (PB). To account for sampling differences, we downsampled sequences to the minimum number of clones in the matching tissue. Normalized clone size distributions were visualized on rank plots (Fig 1). TRB repertoires in both patients and controls were diverse. Highly expanded clones (&amp;gt;5%) were rare in either group. Patients had 1,415,069 unique CDR3 amino acid sequences (CDR3AA), of which 106,446 (7.5%) were shared by ≥2 patients. Among the 106,446 shared CDR3AA, 95.4% were found in controls, and 4.3% TCRs had reported specificity to exogenous (mostly viral) or endogenous antigens in VDJdb. 4,920 (4.6%) of the shared CDR3AA were detected only in patients (median 2 patients (2-25)). Of these, 190 exhibited TCR convergence in ≥1 patient, such that the same CDR3AA was encoded by ≥2 distinct nucleotide sequences. Clustering 4,920 patient-associated CDR3AA using GLIPH (Grouping of lymphocyte interactions by paratope hotspots) identified 43 TCR antigen convergence groups. CDR3AA in each cluster were not significantly expanded in the majority of patients and were not enriched for the high-risk alleles HLA-B*14:02 or B*40:02. Our data suggest that most CDR3AA in AA are private (unique to individual patients). Shared autoreactive CDR3AA may exist in patients but are likely to also be present in healthy individuals. As the next step towards identifying autoreactive T cells, we focused on AA patients with known HLA-I risk alleles. We tested their CD8 + T cells for reactivity with endogenously expressed antigens by stimulating T cells with hematopoietic cell lines engineered to express single HLA-I alleles matching those of the patients (Fig 2). TRB sequencing showed increased clonality and significant expansion of a subset of clonotypes after T cell stimulation. Interferon γ enzyme-linked immunospot assays confirmed the expanded T cells' responsiveness to antigens presented by HLA alleles used for T cell stimulation. Additionally, these expanded T cells demonstrated variable reactivity to cells expressing other HLA alleles from the same patient. Among the 1% of CDR3AA clonotypes most highly expanded with single HLA-I alleles (63-3000-fold), we identified several that were expanded in an HLA-restricted manner. However, several highly expanded CDR3AA were highly expanded with multiple HLA alleles. Potential reasons for expansion of some CDR3AA after stimulation with cells expressing different HLA alleles include 1) binding of the same CDR3AA to different antigens presented by distinct HLA alleles, 2) expansion in response to the same antigens presented by distinct HLA alleles, or 3) expansion in response to non-HLA antigens. In conclusion, our data show diverse and mostly private TRB repertoires in AA patients. Our in vitro findings suggest that much like T cell responses in non-AA individuals, T cell responses in AA are diverse and exhibit flexibility with respect to activation in response to various endogenous antigens in the context of different self HLA-I alleles. Given the diversity of TCR responses observed in AA patients, the tissue specificity of autoimmune attack and established association with risk HLA-I alleles in AA remain a mystery and likely require HSPC-specific autoantigen expression and efficient autoantigen presentation by individual patients' HLA-I alleles.

Quality of Life Analysis in Patients with AA Using the QLQ-AA/PNH-54 at Initial Diagnosis of AA - a Registry Based Analysis

Objectives: Aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH) are ultra-rare, acquired bone marrow failure syndromes (BMFS) with need for long-term care and high morbidity despite recent therapeutic advances. There is a lack of disease-specific assessment tools of quality of life (QoL) in AA/PNH patients. So far, QoL has mostly been estimated according to surrogate parameters (e.g. blood counts, transfusion dependence or toxicity of treatment in AA patients) or has been assessed with tools specifically designed for cancer patients (e.g. EORTC Quality of Life Questionnaire QLQ-C30) or with tools focusing on fatigue (e.g. Functional Assessment of Chronic Illness Therapy, FACIT-Fatigue, PNH patients). Therefore, the QLQ-AA/PNH-54 has been developed to allow a patient tailored QoL assessment in patients with AA or PNH. Here, we present the first descriptive data of the QLQ-AA/PNH-54 of 74 AA patients at the timepoint of initial diagnosis collected between 2018 and 2020 (prior to the SARS-CoV-2 pandemic). Methods: The QLQ-AA/PNH-54 was designed, psychometrically validated, and is currently finally validated for PNH within the IPIG (international PNH interest group)-registry. Parallel to this process, the tool was implemented within the Aachen AA/BMF registry as an instrument for real-life QoL evaluation in AA patients. In total, 54 QoL items regarding physical functioning (21 items), psychological aspects (26 items) and health care related issues (7 items) are comprised. Patients rank the occurrence of each item within the last 14 days on a scale between 0 and 3 (0 = did not occur, 1 = low, 2 = moderate, 3 = severe). Results: 74 AA patients (37 female/ 37 male, mean/median/range age 38.42/ 35.47/ 11-73 years) were included. Patients were diagnosed with nsAA (n=11), sAA (n=23), vsAA (n=18), AA NOS (n=20) and AA/PNH-Overlap (n=2), respectively. Broken down into different functional scales, the most frequently and highest rated scales concerned psychosocial aspects (&amp;gt; 60 % of the patients scored 1-3; &amp;gt; 30% of the patients scored 3). Patients were especially burdened by worries and uncertainties with regards to their future, activity planning security and need for cautiousness in everyday life. Tiredness was the major symptom reported in relation to physical functioning. Patients often feared deterioration of their blood results as the most important health care-related issue. In comparison, low occurrence of pain, orthostatic dysregulation, susceptibility for infections, dyspnea, sleep disturbance and tendency to bleed was reported regarding physical functioning (scored 0 by over 40 to over 50 % of the patients). Similarly, low scores were reported for impairment of activities of daily life in terms of completion of household tasks and hobbies or loss of physical attraction. Conclusion: QoL of AA patients at initial diagnosis was mainly impaired by tiredness and a high psychological burden. Interestingly, complications frequently feared and highlighted by treating physicians had a minor impact on patients' QoL. These results emphasize the importance of further QoL analysis from patient view and recommend to especially focus on the psychological burden of AA patients in patient communication at initial diagnosis.

Hypomethylating Agents Are Associated with High Rates of Hematologic Toxicity in Patients with Secondary MDS/AML That Develops after Acquired Aplastic Anemia

Acquired aplastic anemia (AA) is an autoimmune bone marrow failure (BMF) associated with depletion of hematopoietic stem and progenitor cells. Approximately 15-20% of AA patients treated with immunosuppressive therapy (IST) develop late complications of myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Little is known about managing patients with post-AA myeloid neoplasms (MN). We hypothesized that patients with post-AA MN may be particularly susceptible to hematologic toxicities from cytotoxic therapy because of stem cell deficits. To investigate our hypothesis, we retrospectively analyzed post-AA MN patients treated at our 2 institutions over the past 15 years. Fourteen post-AA MN patients were identified: 11 with MDS, 1 with AML, and 2 with clonal cytopenia of undetermined significance (CCUS). Patients with inherited BMF or allogeneic stem cell transplant (SCT) prior to MN diagnosis were excluded. The median age at MN was 56.5 years (range 5-75) with a median time of 5 years (range 0.25-30) between AA diagnosis and MN. At MN diagnosis, 12 of 14 patients (86%) had a partial or complete response of AA with 5 receiving cyclosporine (CSA) maintenance. Two patients (14%) were on CSA within 6 months of IST without response. After MN diagnosis, CSA was discontinued. Ten adults received hypomethylating agents (HMA) as first-line treatment in preparation for SCT. Three pediatric patients were treated with SCT with no prior HMA. One patient died before receiving treatment. The 10 post-AA patients who received HMA were matched in a 3:1 ratio with a similarly aged, randomly selected non-AA MDS cohort treated with HMA at our center during the same period (Table 1). Compared to patients with non-AA MDS, post-AA MN patients tolerated HMA poorly with frequent, severe complications. Their median per-cycle duration of grade 4 neutropenia was longer (9 v. 1.5 days, p = 0.044), as was median duration of grade 4 thrombocytopenia (13 v. 0 days, p = 0.003). Post-AA patients notably had lower baseline platelets prior to HMA (median 36.5 v. 115 k/mL, p =0.007). Following HMA, the post-AA cohort had higher rates of febrile neutropenia (80% v. 17%, RR 4.8, p &amp;lt; 0.001) and infections ≥ grade 3 (90% v. 13%, RR 6.8, p &amp;lt; 0.001). They also had higher rates of ≥ grade 3 bleeding (40% v. 7%, RR 6.0, p = 0.026) with 2 patients (20%) experiencing intracranial hemorrhage on HMA; no such events occurred in the non-AA cohort. Post-AA patients had more hospital admissions - 18 in 25 total chemotherapy cycles (72%) compared to 12 in 207 cycles (6%) in the matched cohort (RR 12.4, p &amp;lt; 0.001). Post-AA MN patients had more treatment delays &amp;gt;2 weeks (28% v. 8% of planned treatment cycles, RR 3.4, p = 0.01) and dose reductions (40% v. 13%, RR 3.0, p = 0.089). HMA was discontinued due to treatment-emergent adverse events (TEAEs) in 70% of post-AA cases v. 3% of non-AA patients (RR 21.0, p &amp;lt; 0.001). Consequently, post-AA MN patients received fewer cycles of HMA compared to non-AA patients (median 2.5 v. 6, p = 0.021). Death occurred following TEAEs in 20% of post-AA MN patients; no deaths on HMA occurred in the non-AA cohort (RR 14.1, p = 0.058). Among surviving patients, SCT was delayed in 20% of the non-AA cohort due to TEAEs, while no delays occurred in the matched cohort. The median months from final chemotherapy cycle to SCT were 4 (range 1-12) in post-AA v. 1 (1-3) in non-AA, while median months from MN diagnosis to SCT were 8.5 (4-21) in post-AA v. 5 (4-15) in non-AA. For all 14 post-AA MN patients, including those not treated with HMA, overall survival (OS) from MN diagnosis was 71% (95% CI 51-99) at 1 year and 56% (95% CI 34-90) at 3 years. OS of post-AA MN patients differed significantly (p = 0.011) based on treatment with SCT. Among the 5 who did not receive SCT, 4 died within 3 years of MN, while 1 patient is alive 13 months from diagnosis receiving supportive care after intracranial hemorrhage during the first cycle of HMA. In contrast, 7 of 9 (78%) patients who received SCT were alive 3 years after MN diagnosis. Of the 6 patients treated with SCT after HMA, 5 stopped HMA due to toxicity, all had morphologic dysplasia at SCT, and 2 were transplanted with ≥ 5% marrow blasts. Our study shows that patients with MN following antecedent autoimmune AA are at high risk of severe toxicities with standard HMA regimens and have difficulty tolerating repeated cycles. Our results do not support routine use of HMA prior to SCT in this patient population and suggest that early SCT may be the most suitable strategy.

Aplastic anaemia treated using eltrombopag in a dog

AbstractA 2‐year‐old, neutered, female beagle was presented to a referral hospital for investigation of pancytopenia. The patient had a history of recurrent infections and, on previous blood tests, anaemia, leukopenia and thrombocytopenia were detected. At the time of presentation, the patient had been treated for 2 weeks with omeprazole, amoxicillin‐clavulanic acid, marbofloxacin and gabapentin, and for 3 months with prednisolone, in decreasing doses. A bone marrow aspirate and core biopsy were performed. Hypoplastic bone marrow was observed. Once underlying infectious diseases and exposure to toxins were ruled out, a diagnosis of aplastic anaemia was made. The patient was treated with eltrombopag, a thrombopoietin receptor agonist that stimulates primitive haematopoietic stem cells, used for the treatment of aplastic anaemia in humans. One week after starting eltrombopag treatment, all the affected cellular lines were recovered. The patient continued in remission 7 months after treatment.

Diagnostic utility of mast cell analysis in hypoplastic bone marrows for differentiation of aplastic anaemia from hypoplastic myelodysplastic neoplasm: A retrospective study

Background: Haematological disorders characterized by hypocellular marrow like aplastic anaemia (AA) and hypocellular myelodysplastic neoplasm (MDS-h) are diagnostic challenges as the clinical and morphological features overlap, while the treatment and prognosis differ. Bone marrow mast cell quantification is proposed as a supplementary diagnostic and prognostic tool to differentiate AA from MDS-h. We aim to study the distribution of mast cells in hypoplastic marrow and determine its role in differential diagnosis of AA and MDS-h. Methods: We analysed bone marrow biopsies of 65 cases of hypoplastic/aplastic marrow received during the year 2015-2021 for the distribution of mast cells using Toluidine Blue special staining. Hematopoietic stem cells were assessed with the help of CD34 immunohistochemistry. Results: Increased mast cells were noted in 55.4% of all the cases, of which 48% were cases of AA and 21% were cases of MDS-h (P: 0.04). Overall, 76% of AA and 33% of MDS-h cases showed increased numbers of mast cells. Reduced hematopoietic stem cells were noted in 69.4% of the cases with elevated mast cells (P: 0.1). Conclusions: Mast cell quantification in trephine biopsy of AA and MDS-h can act as a supplementary diagnostic tool and guide the management of the respective entities. Understanding its role in the bone marrow niche can enhance stem cell transplant treatment.

Improving the diagnosis of myelodysplastic syndrome by red blood cell parameters.

To investigate the value of red blood cell parameters in Myelodysplastic syndrome (MDS) diagnosis and their relations to MDS subtypes and risk groups. The red blood cell parameter [mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and red cell distribution width (RDW)] levels [203 MDS, 99 aplastic anemia (AA), 145 megaloblastic anemia (MA)] were collected from a single-center retrospective cohort. The cut-off values, area under the receiver operating characteristic curve (ROC) curve (AUC), sensitivity and specificity of the four parameters were calculated from the ROC. Furthermore, Kruskal-Wallis test and Dunn's Test were performed to determine erythrocyte parameters in different subtypes and prognostic risks MDS. There are significant statistic differences in RDW (P < 0.001), MCH (P = 0.036) and MCHC (P < 0.001) (MDS vs AA); RDW (P = 0.009), MCV (P < 0.001), MCH (P < 0.001) and MCHC (P = 0.001) (MDS vs MA); MCV (P = 0.011) and MCH (P = 0.008) (higher-risk MDS vs lower-risk MDS). Between MDS and MA, the area under the receiver operating characteristic curve (ROC) curve (AUC) values of MCV, MCH, MCHC, RDW were 0.846, 0.855, 0.617, and 0.593. Between MDS and AA, the AUC values of MCH, MCHC, RDW were 0.609, 0.671, and 0.662, respectively. The red blood cell parameters contribute to the differential diagnosis of MDS, AA and MA and are related to MDS subtypes and risk groups.

The Transcription Factor ETS-1 Correlates with the Increased Age Associated B Cells in Patients with Acquired Aplastic Anemia

The increased IFN-g levels observed in acquired aplastic anemia (AA), have a crucial role in the immune destruction of the hematopoietic progenitors which subsequently lead to the clinical presentation of this rare and complicated disease. We and others have previously shown that the transcription factor T-bet is over-expressed in T cells from patients with AA. Recently it was shown that a subpopulation of B cells also express T-bet; these cells are characterized as age-associated B cells (ABCs) and express high levels of CD11c and CD19, and are negative for CD21. Stimulation of B cells leads to the formation of ABCs, which in turn "talk" to the T cells and stimulate them, leading to IFN-g production. IFN-g may lead to further induction of T-bet expressing B cells (ABCs). Ets-1 is an essential cofactor for STAT1 in the regulation of T-bet in ABCs. A small subset of CD4+helper T cells, circulating T follicular helper cells (Tfh) are also implicated in T-bet expression in ABCs. They are characterized by the surface expression of CXCR5, ICOS, and PD1, the transcription factor Bcl-6, and produce mainly IL-21, but also IL-17, IL-4, and IFN-γ. To date, there is no information on the expression of ABCs and Tfh cells in patients with aplastic anemia. The current study population included 19 patients with AA and 20 healthy volunteers. The diagnosis of AA was based on the criteria of the International Agranulocytosis and Aplastic Anemia Study. Marrow cytogenetics were normal in all aplastic anemia cases and Fanconi anemia was excluded in all patients. Peripheral blood samples were obtained after written informed consent and using protocols approved by the institutional review board of the University of Patras Medical School, Greece. At the time of sampling, 17 out of 19 of the patients included in the study were at initial diagnosis before receiving any treatment and two patients were in complete remission and off any immunosuppressive treatment. The ABCs, Tfh, and regulatory T cell populations were examined using flow cytometry. We first measured the frequency of ABCs (results are in % ± SEM). All patients had significantly increased numbers of ABCs compared to healthy volunteers (3.68 ± 0.82% vs 0.94 ± 0.34%, p=0.022, Figure 1A). In the two cases in remission, the ABCs levels were lower than the levels of patients at diagnosis. We further examined if there were any differences in the percentages of T follicular helper cells; Patients also showed increased levels of Tfh cells compared to healthy controls (4.02± 1.01% vs 1.11 ± 0.10%, p=0.023, Figure 1A). The patients showing increased levels of ABCs and Tfh cells were also examined for the presence of regulatory T cells (Tregs) as determined by the expression of CD4+ CD25hi , CD127low expression. As expected patients with aplastic anemia showed decreased levels of Tregs compared to healthy volunteers (1.31 ± 0.26 % vs 2.33 ± 0.36%, p=0.03, Figure 1A) . To further explore the mechanism involved in the increased expression of these two cell populations in AA patients, we examined the intracellular Ets-1 protein levels. AA patients showed statistically significant increased Ets-1 protein levels compared to controls (western blot, Figure 1B). Ets-1 protein levels correlated with the increased ABCs counts. Stat-1 protein levels were comparable between patients and controls, as previously described. In this study we explored the role of ABCs, the T-bet expressing B cells, in the immune pathogenesis of AA. We show for the first time that ABCs are increased along with increased pTfh cells, which are required for ABCs formation. The transcription factor Ets-1 is increased in AA patients and this could be one of the potential mechanisms for the increased ABCs. Whether these alterations are a consequence of increased IFN-g from polarized Th1 cells is not fully understood. One possible explanation could be that the IFN-g produced by activated T cells leads to increased numbers of circulating ABCs; these ABCs induce further the IFN-g production leading to a vicious cycle of IFN-g production in effect jeopardizing hematopoietic stem cell survival, leading to the clinical presentation of AA. Based on our results, it is proposed that T-bet has a central role not only in T but also in a small B cell subpopulation that seems central in AA pathogenesis. The development of agents that specifically target T-bet+ cells could possibly be used as novel therapeutic agents for AA but also for other autoimmune diseases. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Outcomes of Older Patients with Aplastic Anemia Treated with Frontline Anti-Thymocyte Globulin (ATG)-Based Immunosuppressive Therapy

Background: Advances in the treatment of aplastic anemia (AA), such as the addition of eltrombopag (EPaG) to immunosuppressive therapy (IST) and the expanded use of unrelated and haploidentical stem cell transplant (SCT) have steadily improved outcomes. However, little is known about the characteristics and outcomes of patients (pts) ≥ 60 years (yrs) of age with newly diagnosed AA who have been treated with an ATG-based regimen. Presumed low bone marrow (BM) reserves, higher frequency of underlying clonal hematopoiesis, intolerance to therapy, comorbidities, and challenges in proceeding to salvage SCT have led to the speculation that response and survival of these pts to IST may be inferior than their younger counterparts. Methods: We retrospectively analyzed the characteristics and outcomes of pts ≥ 60 yrs of age (OLDER) at the time of diagnosis of AA treated with frontline (F/L) ATG based therapy at our center and compared them to pts < 60 yrs of age (YOUNG) treated with F/L ATG over the same time period. We captured their clinical characteristics, cytogenetic abnormalities, mutations in DNMT3A (D), ASXL1 (A) and TET2 (T), exposure to EPaG, response, time to response (TTR) and survival. Overall response included complete and partial response per the standard definitions. Relapse free survival (RFS) was tabulated from the time of best response to loss of response, 2nd ATG infusion, salvage SCT or death (whichever was earlier) and overall survival was tabulated from the time of response to death from any cause. Results: From Jan 2011-May 2012, 43 OLDER pts were treated as F/L for AA of whom 41 (95%) received ATG based therapy; 68 YOUNG pts were treated as F/L for AA over the same time period of whom 62 (91%) received ATG based regimen. Four YOUNG pts vs. no pts in the OLDER group received upfront SCT, and 2 pts in each group were treated with non ATG based therapy: single agent CSA, EPaG, or alemtuzumab. Comparative baseline characteristics are depicted in Table 1. There were no differences in the baseline WBC, peripheral blood lymphocyte percentage and platelet counts between the ATG treated OLDER and YOUNG groups. Both groups had similar frequencies of cytogenetic abnormalities and PNH clones, though OLDER pts had mutations in D-A-T genes compared to the YOUNG group (62% vs. 38%, p=0.05). Both groups had equal concurrent exposure to EPaG with ATG. Cumulatively 23/41 (56%) pts in the OLDER group had an overall response (OR) compared to 43/62 (70%) pts in the YOUNG group (p=0.1); 11/23 (48%) and 23/43 (53%) responders in each group attained CR respectively. There were no differences in OR rates in both groups based on concurrent EPaG exposure: 61% vs. 46% with and without EPaG, respectively, in the OLDER group (p=0.5) and 74% vs 60%, respectively, (p=0.38) in the YOUNG group. On logistic regression analysis using baseline platelet counts, PB lymphocyte (%), D-A-T mutations, karyotype, and EPaG use as covariates, none affected the odds of OR in the 2 groups. The median TTR was 111 days (range, 10-323 days) and 177 days (51-410) in YOUNG AND OLDER groups, respectively; and this was not affected by EPaG use in either group. At a median follow of 38 months (mos) from ATG initiation (53 mos for the OLDER group and 32 mos for the YOUNG group), the median RFS was 49 mos and 39 mos (p=0.6) and median OS 55 vs. not reached (NR) (p <0.0001) in OLDER and YOUNG groups respectively (Fig.1). Significantly more pts in the YOUNG group underwent a subsequent SCT (19% vs. 5%) due to loss of response/ no response, possibly accounting for the higher OS rates. Rates of transformation to MDS or AML was 5% in both groups. Conclusion: Frontline ATG based IST in older pts with AA is a feasible and safe treatment option with promising response rates of 56% and median RFS more than 4 years; figures which are comparable to younger pts with AA treated with IST. The overall risks of transformation to MDS/AML on long term follow-up remain low (≈5%). Further studies assessing the response of the ATG+EPaG combination in these pts and the possibilities of clonal evolution with time needs to be conducted. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Assessment of Hepatic Profile in Acquired Aplastic Anemia: An Experience From Pakistan.

Introduction: Aplastic anemia (AA) is characterized by pancytopenia and hypocellular marrow in the absence of an abnormal infiltrate or increase in reticulin fibrosis. The diagnosis of AA is challenging at times due to decreased cellularity and overlapping morphological features with other bone marrow failure syndromes. Hepatitis-associated aplastic anemia (HAAA) is a rare variant in which patients typically present with jaundice and hepatitis followed by pancytopenia almost within 6 months. Post-hepatitis AA accounts for approximately 1-5% of cases, and invariably such cases are negative for the known hepatitis virus as well. There is limited literature available to understand the correlation of AA with hepatitis with none reported at the national level in our region. As AA is relatively more prevalent in Southeast Asia as compared to the western world and hepatitis is a prevalent disease in our population, the main purpose of this study was to assess the hepatic profile and determine the association of hepatitis in AA at the time of diagnosis.Materials and methods: A cross-sectional study was carried out at the National Institute of Blood Disease and Bone Marrow Transplantation, Karachi, from November 2019 to December 2020 after the informed consent from patients. The study included all treatment-naïve patients of acquired AA with no prior history of taking steroids, immunosuppressive treatment, or chemoradiation therapy. Liver function tests, complete blood count, prothrombin time (PT), and activated partial thromboplastin time were performed, along with viral profiles (HAV, Hep B, Hep C, and HIV). SPSS version 23 (IBM Corp., Armonk, NY) was used for statistical analysis. Mean and standard deviations were computed for quantitative variables while percentages and frequencies were reported for qualitative variables. T-test was used to observe the main difference between groups and a p-value <0.05 was considered to be significant.Results: Out of a total of 351 patients, 29 (8.2%) patients with AA tested positive for viral hepatitis. Hepatitis A was the most prevalent hepatitis (4.0%), followed by hepatitis C (3.7%). The comparison of platelet counts in patients with and without hepatitis was reported to be of statistical significance (p-value < 0.05). A significant statistical difference (p-value < 0.0001) was found in platelet count and PT in patients of AA with and without hepatitis.Conclusion: Overall, this study revealed that <10% of patients of AA had a positive screening for hepatitis A, B, and C and low platelet count, and PT was statistically significant when compared between the patients with and without hepatitis. Hepatitis being prevalent in our part of the world might have an important causal association with AA. Patients with AA should be screened for liver functions and viral hepatitis at the time of diagnosis. In addition to hepatitis A, B, and C and HIV, other causes of hepatitis should also be screened such as parvovirus B19, human herpes virus 16, and adenovirus which are not included in routine diagnostic viral testing panel.

Exclusive diagnosis of aplastic anemia

As an independent disease, aplastic anemia (AA) has been recognized for more than a century. When AA is diagnosed, other non-AA bone marrow failures should be excluded. It is termed as exclusive diagnosis of AA. The exclusive diagnosis of AA is helplessly based on that there is no parameter by which AA can be sensitively and specifically diagnosed now. So further searching for the meaningful diagnostic parameters of AA should be carried on to establish a direct diagnostic protocol of this disease and make it possible to differentiate it clearly from other bone marrow failure disease such as congenenital bone marrow failure, hypoplastic myelodysplastic syndromes, AA-paroxysmal nocturnal hemoglobinuria syndromes, large granules lymphocyte leukemia, clonal cytopenia of undetermined significance, immunorelated pancytopenia, acute hemopoietic arresting and idiopathic cytopenia of undetermined significance. The new markers and technologies being helpful for distinguishing AA from other bone marrow failures should be used in diagnosing AA. Correct understanding and application of exclusive diagnosis is not only related to the correctness of diagnosis and treatment of excluded diseases, but also to the quality of AA diagnosis, treatment and research.

Sars-Cov-2 Infection Associated with Aplastic Anemia and Pure Red Cell Aplasia

Introduction: Aplastic anemia (AA) is a life-threatening disorder characterized by pancytopenia and a hypocellular bone marrow. Pure red cell aplasia (PRCA) is a similar disorder with primary reduction in the red blood cell population and virtual absence of erythroid precursors in the bone marrow. While the etiology of immune mediated marrow failure is multifactorial, preceding viral infections have been associated with the disease; these include parvovirus B19, cytomegalovirus, and Epstein-Barr virus. We present four cases of immune mediated marrow failure with either preceding or simultaneous SARS-CoV-2 infection.Methods: The medical records of patients treated for AA or PRCA at the University of Texas Southwestern Medical Center, Parkland Hospital, and the National Institutes of Health (NIH) were reviewed for SARS-CoV-2 infection. Four patients without prior hematological diseases were identified who had SARS-CoV-2 infection prior to or with simultaneous the diagnosis of AA or PRCA.Results: Patient #1 was a 22-year-old white female who was diagnosed with asymptomatic COVID-19 10 days prior to her pancytopenia and AA diagnosis was confirmed by bone marrow biopsy (5% cellularity; Table 1). Her extensive work-up including HIV, hepatitis panel, immunoglobulins, B12 and folate was negative, and she underwent HLA-matched family donor hematopoietic stem cell transplant. Patient #2 was a 69-year-old Asian female who presented to her primary care physician with symptoms of fatigue and was found to be pancytopenic. CBC from a few months prior was completely normal. Further work-up was positive for COVID-19 and negative for HIV, nutritional deficiency, or hemolysis. She did not have respiratory symptoms, was eventually diagnosed with pRBC and platelet transfusion-dependent severe AA (5-10% cellularity on bone marrow), and underwent treatment with cyclosporine, equine antithymocyte globulin, and eltrombopag. She has had a partial response to this therapy. Both patients had bone marrow specimens stained for SARS-CoV-2 by immunohistochemistry that were negative. Patient #3 was a 76-year-old white male who was diagnosed with COVID-19 4 months prior to presenting with a non-ST segment myocardial infarction and found to be profoundly anemic, requiring pRBC transfusion. He re-presented with chest pain one week later and was found to be anemic again, and required transfusion. A trial of darbepoetin alfa was unsuccessful. Extensive work-up for malignancy, infection, and autoimmune etiologies were negative. He was diagnosed with PRCA based on the bone marrow biopsy and initiated treatment with cyclosporine. Patient # 4 was diagnosed with severe AA (presenting as pancytopenia) and COVID-19 infection. He had fatigue for one month and fever, chills and sore throat one-week prior seeking medical care. Testing for hepatitis, HIV, EBV, and CMV was negative. He was treated on a clinical trial (NCT04304820) at NIH with cyclosporine and eltrombopag until SARS-CoV-2 PCR was negative then received equine anti-thymocyte globulin. He has achieved a complete hematologic response at 6 months and remains well at last follow-up.Conclusion: The four patients described had minimal respiratory COVID-19 symptoms, but they presented with cytopenia and were eventually diagnosed with bone marrow failure. It is possible that this is co-incidental due to the high prevalence of SARS-CoV-2. However, there is emerging evidence that COVID-19 pneumonia is a hyperinflammatory and immune dysregulated state improved by dexamethasone therapy. Other immune mediated hematologic conditions, such as autoimmune hemolytic anemia and immune thrombocytopenia, have been reported. The onset from infection to cytopenia appears rapid, although patients often presented with symptoms for many days prior to diagnosis and thus testing may have been delayed from the onset of infection. This case series does not provide a mechanistic link between SARS-CoV-2 infection and bone marrow failure, but it raises the possibility that SARS-CoV-2 may mediate an immunologic response that contributes to marrow failure. Patients appear to respond well to standard immunosuppressive treatment. Further cases and studies are needed to determine if this is directly linked to SARS-CoV-2 and whether the natural history and response to standard therapy is different than idiopathic cases. [Display omitted] DisclosuresYoung: Novartis: Research Funding.