Prognostic value of paroxysmal nocturnal haemoglobinuria clone presence in aplastic anaemia patients treated with combined immunosuppression: results of two-centre prospective study

Comparison of human leukocyte antigen in patients with paroxysmal nocturnal hemoglobinuria of different clone sizes

Glycosylphosphatidylinositol-anchored protein-deficient hematopoietic stem and progenitor cell development caused by PIGA mutations cannot fully explain the pathogenesis of paroxysmal nocturnal hemoglobinuria (PNH). Herein, patients newly diagnosed with PNH at our hospital between April 2019 and April 2021 were recruited. The human leukocyte antigen (HLA) class I and II loci were analyzed, and patients were stratified by PNH clone sizes: small (< 50%) and large (≥ 50%). In 40 patients (29 males; 72.5%), the median PNH clone size was 72%. Thirteen (32.5%) and twenty-seven (67.5%) patients harbored small and large PNH clones, respectively. DRB1*15:01 and DQB1*06:02 had higher frequencies in patients with PNH than in healthy controls (adjusted P-value = 4.10 × 10-4 and 4.10 × 10-4, respectively). Whole HLA class I and II allele contributions differed (P = 0.046 and 0.065, not significant difference) when comparing patients with small and large PNH clones. B*13:01 and C*04:01 allelic frequencies were significantly higher in patients with small clones (P = 0.032 and P = 0.032, respectively). Patients with small clones had higher class II HLA evolutionary divergence (HED) (P = 0.041) and global class I and II HED (P = 0.019). In the entire cohort, 17 HLA aberrations were found in 11 (27.5%) patients. No significant differences in HLA aberrations were found between patients with small or large clones. In conclusion, patients with small clones tended to have a higher frequency of immune attack-associated alleles. A higher HED in patients with small clones may reflect a propensity for T cell-mediated autoimmunity. HLA aberrations were similar between patients with small and large clones.

Treatment of newly diagnosed severe aplastic anemia in children: Evidence-based recommendations

Severe aplastic anemia (SAA) is a rare potentially fatal hematologic disorder. Although overall outcomes with treatment are excellent, there are variations in management approach, including differences in treatment between adult and pediatric patients. Certain aspects of treatment are under active investigation in clinical trials. Because of the rarity of the disease, some pediatric hematologists may have relatively limited experience with the complex management of SAA. The following recommendations reflect an up-to-date evidence-based approach to the treatment of children with newly diagnosed SAA.

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.

Activity and safety of eltrombopag in combination with cyclosporin A as first‑line treatment of adults with severe aplastic anaemia (SOAR): a phase 2, single-arm study

BACKGROUND

Antithymocyte globulin (ATG)-based immunosuppression is standard in front-line treatment for people with severe aplastic anaemia without a histocompatible donor or who are 40 years or older. However, ATG requires in-hospital administration, is associated with infusion-related toxicities and has limited availability worldwide. In this study, we investigated the activity and safety of an ATG-free regimen of eltrombopag with cyclosporin A as a potential treatment for patients with severe aplastic anaemia who might not have access to or cannot tolerate horse-ATG.

METHODS

SOAR was a multicentre, single-arm phase 2 trial investigating eltrombopag and cyclosporin in adult (≥18 years) patients with severe aplastic anaemia who were treatment-naive and had an Eastern Cooperative Oncology Group performance status of less than 2. Participants were recruited from 20 hospitals in ten countries. Eltrombopag was initiated at 150 mg (100 mg in patients of Asian ethnicity) and cyclosporin at 10 mg/kg per day (adjusted to a trough of 200-400 μg/L) orally from day 1 to 6 months. The primary outcome was an overall haematological response rate by 6 months in the intention-to-treat population. This is the final report of the primary analysis period. The trial was registered with ClinicalTrials.gov, NCT02998645, and has been completed.

FINDINGS

54 patients were enrolled between May 11, 2017, and March 23, 2020. 34 (63%) patients were male and 20 (37%) were female. 22 (41%) were Asian, 22 (41%) were White, one (2%) was Native American or Alaska Native, one (2%) was Black or African American, and eight (15%) were other race or ethnicity. 35 patients (65%) completed 6 months of treatment with eltrombopag and cyclosporin and six (11%) completed the cyclosporin tapering period up to month 24. Overall haematological response rate by month 6 of treatment was 46% (25 of 54; 95% CI 33-60). The most reported adverse events were increased serum bilirubin (in 22 patients [41%]), nausea (16 [30%]), increased alanine aminotransferase concentration (12 [22%]), and diarrhoea (12 [22%]). Eight patients died on-treatment, but no deaths were considered related to the treatment.

INTERPRETATION

Eltrombopag and cyclosporin was active as front-line treatment of severe aplastic anaemia, with no unexpected safety concerns. This approach might be beneficial where horse-ATG is not available or not tolerated.

FUNDING

Novartis Pharmaceuticals.

Diagnosis of immune pathophysiology in patients with bone marrow failure

Differential diagnosis of pancytopenia with bone marrow (BM) hypoplasia represented by aplastic anemia (AA) is often challenging for physicians, because no laboratory tests have been established, until recently, to distinguish immune-mediated BM failure, which includes acquired AA (aAA) and a subset of low-risk myelodysplastic syndrome (MDS), from non-immune BM failure, which is primarily caused by genetic abnormalities in hematopoietic stem cells (HSCs). HSCs of healthy individuals often undergo somatic mutations, and some acquire phenotypic changes that allow them to escape immune attack against themselves. Once an immune attack against HSCs occurs, HSCs that undergo somatic mutations survive the immune attack and continue to produce their progenies with the same genetic or phenotypic changes. The presence of mature blood cells derived from mutated HSCs in the peripheral blood serves as evidence of the immune-mediated destruction of HSCs. Glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) blood cells and HLA class I allele-lacking (HLA[-]) leukocytes are two major aberrant cell types that represent the immune mechanism underlying BM failure. This review focuses on the importance of identifying immune mechanisms using laboratory markers, including GPI(-) cells and HLA(-) leukocytes, in the management of BM failure.

Comparable outcomes with low-dose and standard-dose horse anti-thymocyte globulin in the treatment of severe aplastic anemia

BACKGROUND

The standard dose (SD) of horse anti-thymocyte globulin (hATG) ATGAM (Pfizer, USA) or its biosimilar thymogam (Bharat Serum, India) for the treatment of Aplastic Anemia (AA) is 40 mg/kg/day for 4 days in combination with cyclosporine. Data on the impact of hATG dose on long-term outcomes are limited. Here, we describe our comparative experience using 25 mg/kg/day (low-dose [LD]) hATG for 4 days with SD for the treatment of AA.

METHODS

We retrospectively studied patients with AA (age > 12 years) who received two doses of hATG combined with cyclosporine. Among 93 AA patients who received hATG, 62 (66.7%) and 31 (33.3%) patients received LD and SD hATG with cyclosporine, respectively. Among these,seventeen(18.2%) patients also received eltrombopag with hATG and cyclosporine. Overall response rates [complete response (CR) and partial response (PR)] of LD and SD hATG groups at 3 months (50% vs. 48.4%; p = 0.88), 6 months (63.8% vs. 71.4%; p = 0.67), and 12 months (69.6% vs. 79.2%; p = 0.167) were comparable. The mean (Standard Deviation) 5-year Kaplan-Meier estimate of overall survival and event-free survival was 82.1 (4.6)% and 70.9 (5.5)% for the study population. The mean (standard deviation) 5-year Kaplan-Meier estimate of overall survival and event-free survival of those who received LD hATG versus SD hATG dose was 82.9 (5·3)% versus 74.8 (10·3)% (P = 0·439), and 75.2 (6.2)% versus 61.4(11.2)% (P = 0·441).

CONCLUSION

Our study revealed that the response rates of patients with AA and LD were similar to those of patients with SD to hATG combined with cyclosporine in a real-world setting.

Prognostic value of pre-treatment PNH clone among the patients with aplastic anemia: a meta-analysis

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) clone can be detected in some patients with aplastic anemia (AA) before treatment. But the prognostic value of the presence of pre-treatment PNH clone for intensive immunosuppressive therapy (IIST) is controversial and no consensus on whether the occurrence of PNH/AA-PNH syndrome is related to pre-treatment PNH clone.

OBJECTIVE

This study aims to summarize the prognostic value of the presence of pre-treatment PNH clone treated with IIST among the AA patients and to elucidate its relationship with the development of PNH / AA-PNH syndrome.

METHODS

All published studies on the prognostic value of pre-treatment PNH clone among AA patients were retrieved. Pooled odds ratio (OR) was calculated to compare the rates, along with 95% confidence intervals (CI) and p value to assess whether the results were statistically significant.

RESULTS

The meta-analysis consisted of 15 studies with a combined total of 1349 patients in the cohort. Pre-treatment PNH clone had a positive effect on AA patients 6-month (pooled OR = 1.49,95% Cl: 1.06-2.08, P = 0.020), 12-month (pooled OR = 3.10,95% Cl: 1.89-5.10, P = 0.000), and overall hematological response rate (pooled OR = 1.69,95% Cl: 1.07-2.68, P = 0.024) after IIST. Patients with pre-treatment PNH clone are more likely to develop PNH/AA-PNH syndrome after IIST(pooled OR = 2.78,95%Cl:1.21-6.39, P = 0.016).

CONCLUSION

Patients with positive pre-treatment PNH clone had better hematological responses to IIST than negative. And, those patients are more likely to develop PNH/AA-PNH syndrome after IIST.

A longitudinal analysis of paroxysmal nocturnal haemoglobinuria-type cells in patients with bone marrow failure: Results of a prospective multi-centre study in Japan

To determine the prevalence and clinical relevance of glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) cell populations (paroxysmal nocturnal haemoglobinuria [PNH]-type cells) in patients with acquired aplastic anaemia (AA) or myelodysplastic syndrome (MDS), we prospectively studied peripheral blood samples of 2402 patients (1075 with AA, 900 with MDS, 144 with PNH, and 283 with other anaemia) using a high-sensitivity flow cytometry assay in a nationwide multi-centre observational study. PNH-type cells were detected in 52.6% of AA and 13.7% of MDS patients. None of the 35 patients with refractory anaemia (RA) with ringed sideroblasts or the 86 patients with RA with excess of blasts carried PNH-type cells. Among the 317 patients possessing PNH-type granulocytes, the percentage of PNH-type granulocytes increased by ≥10% in 47 patients (14.8%), remained unchanged in 240 patients (75.7%), and decreased by ≥10% in 30 patients (9.5%) during 3 years of follow-up. PNH-type granulocyte expansion occurred more frequently (27.1%) in the 144 patients who originally carried PNH-type granulocytes ≥1% than in the 173 patients with PNH-type granulocytes <1% (4.6%). This study confirmed that PNH-type cells are undetectable in authentic clonal MDS patients, and the presence of ≥1% PNH-type granulocytes predicts a higher likelihood of PNH-type cell expansion than with <1% PNH-type granulocytes.

From bone marrow failure syndromes to VEXAS: Disentangling clonal hematopoiesis, immune system, and molecular drivers

Clonal hematopoiesis (CH) is a result of the selective expansion of hematopoietic stem and progenitor cells (HSPCs) carrying somatic mutations originating from a primary HSC. The advent of modern genomic technologies has helped recognizing that CH is common in elderly healthy subjects as a result of the aging bone marrow (BM). CH in healthy subjects without abnormalities in blood counts is known as CH of indeterminate potential. CH is also seen in BM failure (BMF) disorders. Whether CH alarms for the risk to develop malignant evolution in BMF or creates an adaptation to selective pressure is a matter of controversy. As such, a continuum might exist from pre-malignant to malignant hematopoietic diseases. This review summarizes how somatic mutations and immune derangement in HSCs shape disease evolution and describes the complexity of disorders such as VEXAS as the prototypic tetrad of somatic mutations, morphologic features, inflammatory pathways and immune overshooting. In such a view, we interconnect the axis aging and immune-hematopoietic system, which all convey important clues for the risk to develop malignancies.

Significance of paroxysmal nocturnal hemoglobinuria clone in immunosuppressive therapy for children with severe aplastic anemia

OBJECTIVES

To study the association between paroxysmal nocturnal hemoglobinuria (PNH) clone and immunosuppressive therapy (IST) in children with severe aplastic anemia (SAA).

METHODS

A retrospective analysis was performed on the medical data of 151 children with SAA who were admitted and received IST from January 2012 to May 2020. According to the status of PNH clone, these children were divided into a negative PNH clone group (n=135) and a positive PNH clone group (n=16). Propensity score matching was used to balance the confounding factors, and the impact of PNH clone on the therapeutic effect of IST was analyzed.

RESULTS

The children with positive PNH clone accounted for 10.6% (16/151), and the median granulocyte clone size was 1.8%. The children with positive PNH clone had an older age and a higher reticulocyte count at diagnosis (P<0.05). After propensity score matching, there were no significant differences in baseline features between the negative PNH clone and positive PNH clone groups (P>0.05). The positive PNH clone group had a significantly lower overall response rate than the negative PNH clone group at 6, 12, and 24 months after IST (P<0.05). The evolution of PNH clone was heterogeneous after IST, and the children with PNH clone showed an increase in the 3-year cumulative incidence rate of aplastic anemia-PNH syndrome (P<0.05).

CONCLUSIONS

SAA children with positive PNH clone at diagnosis tend to have poor response to IST and are more likely to develop aplastic anemia-PNH syndrome.

The Role of T Lymphocytes in the Pathogenesis of Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell genetic mutation disease that causes defective erythrocyte membrane hemolysis. Its pathologic basis is the mutation of the PIG-A gene, whose product is necessary for the synthesis of glycosylphosphatidylinositol (GPI) anchors; the mutation of PIG-A gene results in the reduction or deletion of the GPI anchor, which leads to the deficiency of GPI-anchored proteins (GPI-APs), such as CD55 and CD59, which are complement inhibitors. The deficiency of complement inhibitors causes chronic complement-mediated intravascular hemolysis of GPI-anchor-deficient erythrocyte. PIG-A gene mutation could also be found in bone marrow hematopoietic stem cells (HSCs) of healthy people, but they have no growth advantage; only the HSCs with PIG-A gene mutation in PNH patients have this advantage and expand. Besides, HSCs from PIG-A-knockout mice do not show clonal expansion in bone marrow, so PIG-A mutation cannot explain the clonal advantage of the PNH clone and some additional factors are needed; thus, in recent years, many scholars have put forward the theories of the second hit, and immune escape theory is one of them. In this paper, we focus on how T lymphocytes are involved in immune escape hypothesis in the pathogenesis of PNH.

The expression and clinical significance of CD59 and FLAER in Chinese adult AML patients

Background

The role of CD59 and fluorescently labeled aerolysin (FLAER) in acute myeloid leukemia (AML) remains unclear and requires further investigation. To explore the relationship between CD59, FLAER, and AML, we investigated CD59 and FLAER expression in AML and analyzed their relationship with clinical characteristics of AML patients.

Methods

We employed flow cytometry (FCM) to analyze CD59 and FLAER expression in 161 AML patients at Tianjin Medical University General Hospital and evaluated its association with sex, white blood cell (WBC) count, platelet (PLT) count, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), D‐Dimer(D‐D), and lactate dehydrogenase (LDH), followed by analyzing its connection with disease progression and complete remission (CR).

Results

CD59 and FLAER deficiencies were identified in AML patients. Compared with CR group, non‐CR group patients revealed more CD59 and FLAER deficiency. Compared with non‐acute promyelocytic leukemia (M3) group, M3 group patients had more CD59 and FLAER deficiency. CD59⁻ level in primordial cells of M3 patients was positively correlated with primordial cell ratio (r = 0.660, p = 0.003). Additionally, we discovered that the decline in CD59 and FLAER levels might be linked to higher D‐D and LDH in AML patients. The difference was statistically significant (p < 0.05).

Conclusions

We demonstrated that the decline in CD59 and FLAER levels was associated with leukemia cell proliferation and abnormal coagulation function in AML, suggesting that they could serve as a predictor of AML coagulation dysfunction, particularly in M3.

The GPI-anchored protein CD109 protects hematopoietic progenitor cells from undergoing erythroid differentiation induced by TGF-β

Although a glycosylphosphatidylinositol-anchored protein (GPI-AP) CD109 serves as a TGF-β co-receptor and inhibits TGF-β signaling in keratinocytes, the role of CD109 on hematopoietic stem progenitor cells (HSPCs) remains unknown. We studied the effect of CD109 knockout (KO) or knockdown (KD) on TF-1, a myeloid leukemia cell line that expresses CD109, and primary human HSPCs. CD109-KO or KD TF-1 cells underwent erythroid differentiation in the presence of TGF-β. CD109 was more abundantly expressed in hematopoietic stem cells (HSCs) than in multipotent progenitors and HSPCs of human bone marrow (BM) and cord blood but was not detected in mouse HSCs. Erythroid differentiation was induced by TGF-β to a greater extent in CD109-KD cord blood or iPS cell-derived megakaryocyte-erythrocyte progenitor cells (MEPs) than in wild-type MEPs. When we analyzed the phenotype of peripheral blood MEPs of patients with paroxysmal nocturnal hemoglobinuria who had both GPI(+) and GPI(-) CD34⁺ cells, the CD36 expression was more evident in CD109^- MEPs than CD109⁺ MEPs. In summary, CD109 suppresses TGF-β signaling in HSPCs, and the lack of CD109 may increase the sensitivity of PIGA-mutated HSPCs to TGF-β, thus leading to the preferential commitment of erythroid progenitor cells to mature red blood cells in immune-mediated BM failure.

Different clinical courses with the same findings: two cases of paroxysmal nocturnal hemoglobinuria presenting with thrombocytopenia

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disease that manifests with chronic intravascular hemolysis, thrombosis, and bone marrow failure. Various degrees of cytopenias accompany the disease. Although laboratory and clinical findings are similar, the disease may show different courses and require different treatments. Herein, we report two different courses of PNH with similar clinical and laboratory findings.

A frequent nonsense mutation in exon 1 across certain HLA-A and -B alleles in leukocytes of patients with acquired aplastic anemia

Leukocytes that lack HLA allelic expression are frequently detected in patients with acquired aplastic anemia (AA) who respond to immunosuppressive therapy (IST), although the exact mechanisms underlying the HLA loss and HLA allele repertoire likely to acquire loss-of-function mutations are unknown. We identified a common nonsense mutation at position 19 (c.19C>T, p.R7X) in exon 1 (Exon1mut) of different HLA-A and -B alleles in HLA-lacking granulocytes from AA patients. A droplet digital PCR (ddPCR) assay capable of detecting as few as 0.07% Exon1mut HLA alleles in total DNA revealed the mutation was present in 29% (101/353) of AA patients, with a median allele frequency of 0.42% (range, 0.071% to 21.3%). Exon1mut occurred in only 12 different HLA-A (n=4) and HLA-B (n=8) alleles, including B*40:02 (n=31) and A*02:06 (n=15), which correspond to 4 HLA supertypes (A02, A03, B07, and B44). The percentages of patients who possessed at least one of these 12 HLA alleles were significantly higher in the 353 AA patients (92%, P.

Predicting response of severe aplastic anemia to immunosuppression combined with eltrombopag

Pretreatment blood counts, particularly an absolute reticulocyte count ≥25×10⁹/L, correlate with response to immunosuppressive therapy in severe aplastic anemia. In recent trials, eltrombopag combined with standard immunosuppressive therapy yielded superior responses than those to immunosuppressive therapy alone. Our single institution retrospective study aimed to elucidate whether historical predictors of response to immunosuppressive therapy alone were also associated with response to immunosuppressive therapy plus eltrombopag. We sought correlations of blood counts, thrombopoietin levels and the presence of paroxysmal nocturnal hemoglobinuria clones with both overall and complete responses in 416 patients with severe aplastic anemia, aged 2-82 years (median, 30 years), initially treated with immunosuppressive therapy plus eltrombopag between 2012 and 2019 (n=176) or with immunosuppressive therapy alone between 1999 and 2010 (n=240). Compared to non-responders, patients in the group of overall responders to immunosuppressive therapy plus eltrombopag had significantly higher pretreatment absolute reticulocyte counts, higher neutrophil counts and reduced thrombopoietin levels, as also observed for the group treated with immunosuppressive therapy alone. Addition of eltrombopag markedly improved the overall response in subjects with an absolute reticulocyte count between 10-30×10⁹/L from 60% (54 of 90) to 91% (62 of 68). Absolute lymphocyte count correlated with complete response in the groups treated with immunosuppressive therapy with or without eltrombopag, especially in adolescents aged ≥10 years and adults, but the correlation was reversed in younger children. Platelet count and the presence of a paroxysmal nocturnal hemoglobinuria clone did not correlate with responses to immunosuppressive therapy. Blood counts remain the best predictors of response to nontransplant therapies in severe aplastic anemia. Addition of eltrombopag to immunosuppressive therapy shifted patients with a lower absolute reticulocyte count into a better prognostic category.

Hematopoietic stem progenitor cells lacking HLA differ from those lacking GPI-anchored proteins in the hierarchical stage and sensitivity to immune attack in patients with acquired aplastic anemia

To characterize glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) and HLA-class I allele-lacking (HLA[-]) hematopoietic stem progenitor cells (HSPCs) in acquired aplastic anemia (AA), we studied the peripheral blood (PB) of 56 AA patients in remission who possessed both (n = 13, Group A) or either GPI(-) (n = 34, Group B) and HLA(-) (n = 9, Group C) cell populations. Seventy-seven percent (10/13) of Group A had HLA(-) cells in all lineages of PB cells, including platelets, while only 23% (3/13) had GPI(-) cells in all lineages, and the median percentage of HLA(-) granulocytes in the total granulocytes (21.2%) was significantly higher than that of GPI(-) granulocytes (0.28%, P < 0.05). The greater lineage diversity in HLA(-) cells than in GPI(-) cells was also seen when Group B and Group C were compared. Longitudinal studies of seven patients in Group A showed a gradual decrease in the percentage of HLA(-) granulocytes, with a reciprocal increase in the GPI(-) granulocytes in four patients responding to cyclosporine (CsA) and an increase in the HLA(-) granulocytes with a stable or declining GPI(-) granulocytes in three patients in sustained remission off CsA therapy. These findings suggest that HLA(-) HSPCs differ from GPI(-) HSPCs in the hierarchical stage and sensitivity to immune attack in AA.

Clinical and prognostic significance of small paroxysmal nocturnal hemoglobinuria clones in myelodysplastic syndrome and aplastic anemia

In this large single-centre study, we report high prevalence (25%) of, small (<10%) and very small (<1%), paroxysmal nocturnal hemoglobinuria (PNH) clones by high-sensitive cytometry among 3085 patients tested. Given PNH association with bone marrow failures, we analyzed 869 myelodysplastic syndromes (MDS) and 531 aplastic anemia (AA) within the cohort. PNH clones were more frequent and larger in AA vs. MDS (p = 0.04). PNH clone, irrespective of size, was a good predictor of response to immunosuppressive therapy (IST) and to stem cell transplant (HSCT) (in MDS: 84% if PNH+ vs. 44.7% if PNH−, p = 0.01 for IST, and 71% if PNH+ vs. 56.6% if PNH− for HSCT; in AA: 78 vs. 50% for IST, p < 0.0001, and 97 vs. 77%, p = 0.01 for HSCT). PNH positivity had a favorable impact on disease progression (0.6% vs. 4.9% IPSS-progression in MDS, p < 0.005; and 2.1 vs. 6.9% progression to MDS in AA, p = 0.01), leukemic evolution (6.8 vs. 12.7%, p = 0.01 in MDS), and overall survival [73% (95% CI 68–77) vs. 51% (48–54), p < 0.0001], with a relative HR for mortality of 2.37 (95% CI 1.8–3.1; p < 0.0001) in PNH negative cases, both in univariate and multivariable analysis. Our data suggest systematic PNH testing in AA/MDS, as it might allow better prediction/prognostication and consequent clinical/laboratory follow-up timing.

The predictive value of pre-treatment paroxysmal nocturnal hemoglobinuria clone on response to immunosuppressive therapy in patients with aplastic anemia: a meta-analysis

BACKGROUND

Although pre-treatment paroxysmal nocturnal hemoglobinuria (PNH) clone has been reported in a fraction of aplastic anemia (AA) for a long time, its predictive value on response to immunosuppressive therapy (IST) remained debatable. Therefore, we conducted a meta-analysis to elaborate this issue.

METHODS

The identified articles were retrieved from five English databases PubMed, EMBASE, Web of Science, Medline, the Cochrane Library, and four Chinese databases Weipu, Wangfang, China National Knowledge Infrastructure (CNKI), and SinoMed. We extracted odds ratios (ORs) and the corresponding 95% confidential intervals (CIs) for response to IST in AA patients with pre-treatment PNH clone versus those without from the available studies.

RESULTS

Twelve studies covering 1787 patients were included this meta-analysis. The pooled ORs indicated that the pre-treatment PNH clone had no impact on 3-month response (pooled OR: 1.323, 95% CI: 0.260-6.735, p = 0.736), 6-month response (OR: 1.668, 95% CI: 0.802-3.470, p = 0.171), and overall response (OR: 2.220, 95% CI: 0.870-5.665, p = 0.095), including overall response in pediatric patients (OR: 1.919, 95% CI: 0.378-9.738, p = 0.432). However, pre-treatment PNH clone had a favorable impact on 12-month response (OR: 2.725, 95% CI: 1.525-4.870, p = 0.001).

CONCLUSION

Pre-treatment PNH clone is associated with favorable 12-month response to IST in AA, the underlying mechanism needs further exploring.

Advances in Hematopoietic Stem Cell Transplantation for Patients with Paroxysmal Nocturnal Hemoglobinuria

In the era of eculizumab, the number of patients with paroxysmal nocturnal hemoglobinuria (PNH) who undergo hematopoietic stem cell transplantation (HSCT) has decreased significantly. However, owing to the possibility of severe aplastic anemia (AA) or a suboptimal response to eculizumab, HSCT still plays an important role in the treatment of patients with PNH combined with AA or recurrent hemolysis-related symptoms despite its high level of risk. Here we review studies involving patients with PNH who underwent HSCT over the past 15 years and conclude that patients with refractory AA/PNH and patients with severe classical PNH are candidates for HSCT in countries where eculizumab is unavailable. The major causes of death from transplantation include graft-versus-host disease (GVHD), infection, and thrombotic microangiopathy. A haploidentical donor is a potential choice for patients without an HLA-matched donor. In addition, the use of eculizumab in combination with HSCT may help prevent GVHD.

Small PNH clones detected by fluorescent aerolysin predict a faster response to immunosuppressive therapy in patients with severe aplastic anaemia

Objectives: To clear the obscure conclusion on the prediction value of paroxysmal nocturnal haemoglobinuria (PNH) clones in severe aplastic anaemia (SAA) patients treated with immunosuppressive therapy (IST). Methods: We retrospectively analyzed 219 consecutive SAA patients treated with IST from October 2008 to October 2015 and evaluated the haematological responses to IST. Results: The presence of a PNH clone was detected in 55 (25.1%) patients prior to IST [37/88 by flow cytometry (FCM) and 18/131 by fluorescent aerolysin (FLAER)] and 27 disappeared after IST (23/37 in initial FCM group, 4/18 in initial FLAER group, p = 0.005). In patients without an initial clone, 12 (30.0%) cases in FCM and 17 (19.5%) in FLAER groups presented a PNH clone at least once after IST (p < 0.001). In patients with a pre-treatment PNH clone detected by FCM, the 3-, 6- and 12-month response rates were higher than patients without (p = 0.006; 0.002 and 0.002, respectively). And in FLAER group, the 3-month response rate was significantly higher in those with a prior clone (p = 0.017), however, the 6- and 12-month response rates showed no differences (p = 0.105, p = 0.144, respectively). By multivariate analysis, a shorter interval between diagnosis and treatment is associated with a better response and survival. Conclusions: A more reliable FLAER method allows us to draw a conclusion that PNH clone predicts a faster response but not a higher response rate to IST. Once a diagnosis is confirmed, the IST should be initiated as soon as possible.

Relationship between immune status after ATG treatment and PNH clone evolution in patients with severe aplastic anemia

OBJECTIVES

To investigate the relationship between immune status and paroxysmal nocturnal hemoglobinuria (PNH) clonal evolution of severe aplastic anemia (SAA) patients who received anti-human thymocyte globulin (ATG) treatment.

METHODS

The clinical data of 102 SAA patients who received ATG were collected and retrospectively analyzed. The remission rate, remission time, response rate, hematopoietic, and immune status were compared. Malignant clones were also observed.

RESULTS

The remission rate of the group with PNH clones appeared after treatment was significantly higher than the group without PNH clones. The response rate at 12 months of the groups with PNH clones was significantly higher than the group without PNH clones. The recovery of Hb and Ret % of patients with PNH clones was earlier than the patients without PNH clones. The reduction of percentage of CD8⁺ HLA-DR⁺ /CD8⁺ and Th1/Th2 ratio of patients with PNH clones was both earlier than the patients without PNH clones. Six patients developed myelodysplastic syndromes (MDS).

CONCLUSION

In SAA patients with PNH clones, the cytotoxic T-cell function and Th1 cell number recovered more quickly and had better response to IST. A small number of SAA patients with or without PNH clones developed MDS malignant clones.

The clinical significance of PNH-phenotype cells accounting for < 0.01% of total granulocytes detected by the Clinical and Laboratory Standards Institute methods in patients with bone marrow failure

Small populations of glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) cells accounting for up to 0.01% of total granulocytes can be accurately detected by a high-sensitivity flow cytometry (FCM) assay established by the Clinical and Laboratory Standards Institute (CLSI method) and have a prognostic value in bone marrow failure (BMF); however, the significance of GPI(-) granulocytes accounting for 0.001-0.009% of granulocytes remains unclear. To clarify this issue, we examined the peripheral blood of 21 BMF patients in whom minor (around 0.01%) populations of GPI(-) granulocytes had been previously detected by a different high-resolution FCM method (OPTIMA method, which defines ≥ 0.003% GPI(-) granulocytes as an abnormal increase) using both the CLSI and OPTIMA methods simultaneously. These two methods detected an "abnormal increase" in GPI(-) granulocytes in 10 patients (48%) and 17 patients (81%), respectively. CLSI detected 0.002-0.005% (median, 0.004%) GPI(-) granulocytes in 7 patients who were deemed positive for PNH-type cells according to the OPTIMA method, which detected 0.003-0.012% (median 0.006%) GPI(-) granulocytes. The clone sizes of GPI(-) cells detected by each assay were positively correlated (r = 0.994, p < 0.001). Of the seven patients who were judged positive for PNH-type cells by OPTIMA alone, five received immunosuppressive therapy, and all of them achieved a partial or complete response. GPI(-) granulocytes detected in BMF patients by the CLSI method should thus be considered significant, even at percentages of < 0.01%.

Long-term outcomes of 172 children with severe aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine

This study retrospectively analyzed the clinical outcome of 172 children with newly diagnosed severe aplastic anemia (SAA) between January 2008 and April 2018, who received rabbit antithymocyte globulin (ATG) and cyclosporine (CsA) as first-line treatment. The median age at diagnosis was 5 years (range, 1-14). The overall response rates were 22.7%, 45.3%, and 61% at 40 days, 3 months, and 6 months, respectively, after rabbit ATG. In multivariate analysis, mild disease severity was the only predictor of favorable response at 6 months (P = 0.006). In the present study, median follow-up period was 63 months (range, 1-135). The 5-year overall survival (OS) and failure-free survival (FFS) rates were 90.5% and 70.4%. Multivariate analysis showed that erythroid burst-forming units (BFU-E) > 2/10⁵ bone marrow mononuclear cell (BMMNC) (P = 0.037) and time interval before IST ≤ 30 days (P = 0.017) were independent positive predictors for OS, meanwhile BFU-E > 2/10⁵BMMNC (P = 0.029) was the only favorable prognostic factor for FFS.

PNH Clones for Aplastic Anemia with Immunosuppressive Therapy: A Systematic Review and Meta-Analysis

OBJECTIVES

PNH clones, also aptly called "escape clones," are evidence of acquired immune-mediated bone marrow failure and have a high prevalence in patients with aplastic anemia (AA). Several studies have reported contradictory results regarding the impact of PNH clones on AA patients with immunosuppression treatment, and PNH clones have not been confirmed as positive predictors of response in the AA guidelines of the British Society for Standards in Haematology.

METHODS

We performed a meta-analysis to address this issue by searching for articles in PubMed, EMBASE, The Coch-rane Library, Web of Science, and ClinicalTrials.gov, and for abstracts from the annual meetings of the American Society of Hematology and the European Hematology Association. We included 1,236 participants from 11 cohort-controlled studies. Our primary outcome was the 6-month hematologic response with a secondary outcome of the mortality rate within 3 months.

RESULTS

A better response rate was observed in the PNH+ group than in the PNH- group (odds ratio [OR] 2.85; 95% confidence interval [CI] 2.17-3.75; p < 0.00001), and further subgroup analysis strengthened the outcome, with minor heterogeneity in non-Asian countries. In contrast, the early mortality was not significantly different between the PNH+ and PNH- groups (OR 0.54; 95% CI 0.26-1.10; p = 0.09).

CONCLUSIONS

The meta-analysis suggested an evidence-based role for PNH clones in predicting a better response in AA patients with immunosuppression.

[Immunosupressive therapy of aplastic anemia patients: successes and failures (single center experiment 2007-2016)]

Treatment programs for patients with acquired aplastic anemia include two main therapeutic options: allogeneic bone marrow transplantation and combined immunosuppressive therapy (IST). However, combined IST remains the method of choice for most adult AA patients. This study included 120 AA patients who received IST at the National Research Center for Hematology in 20072016. The analysis was applied to 120 patients. Median age was 25 (1765) years, M/F: 66/54, SAA/NSAA: 66%/34%. Effectiveness of IST was carried out in 120 patients with AA. This group did not include 8 SAA patients who died during the first 3 months from the start of treatment from severe infectious complications (early deaths 6.2%) and 2 AA patients who dropped out of surveillance. The observation time was 55 (6120) months. Paroxysmal nocturnal hemoglobinuria (PNH clone) was detected in 67% of AA patients. The median PNH clone size (granulocytes) was 2.5 (0.0199.5)%. The treatment was according to the classical protocol of combined IST: horse antithymocytic globulin and cyclosporin A. Most of patients (87%) responded to combined immunosuppressive therapy. To achieve a positive response, it was sufficient to conduct one course of ATG to 64% of patients, two courses of ATG 24% of patients and 2% of patients responded only after the third course of ATG. A positive response after the first course was obtained in 64% of patients included in the analysis. Most of the responding patients (93%) achieve a positive response after 36 months from the start of treatment. Therefore, the 3rd6th months after the first course of ATG in the absence of an answer to the first line of therapy can be considered the optimal time for the second course of ATG. This tactic allows to get an answer in another 58% of patients who did not respond to the first course of ATG. The probability of an overall 10-year survival rate was 90% (95% confidence interval 83.696.2).

Laboratory studies for paroxysmal nocturnal hemoglobinuria, with emphasis on flow cytometry

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematopoietic stem cell disorder caused by somatic mutations in the PIG-A gene, leading to the production of blood cells with absent or decreased expression of glycosylphosphatidylinositol-anchored proteins, including CD55 and CD59. Clinically, PNH is classified into three variants: classic (hemolytic), in the setting of another specified bone marrow disorder (such as aplastic anemia or myelodysplastic syndrome) and subclinical (asymptomatic). PNH testing is recommended for patients with intravascular hemolysis, acquired bone marrow failure syndromes and thrombosis with unusual features. Despite the availability of consensus guidelines for PNH diagnosis and monitoring, there are still discrepancies on how PNH tests are carried out, and these technical variations may lead to an incorrect diagnosis. Herein, we provide a brief historical overview of PNH, focusing on the laboratory tests available and on the current recommendations for PNH diagnosis and monitoring based in flow cytometry.

Revisiting acquired aplastic anaemia: current concepts in diagnosis and management

Acquired aplastic anaemia is a rare, serious, immunologically mediated bone marrow failure syndrome, characterised by marrow hypoplasia of varying severity and significant pancytopenia. Careful attention and investigation, including molecular testing, is required to confirm the diagnosis and exclude other mimicking conditions, such as inherited bone marrow failure syndromes. In a proportion of patients, the disease evolves to myelodysplasia or acute myeloid leukaemia and in some there is an association with paroxysmal nocturnal haemoglobinuria. The disease has a major impact on patient quality of life. Haemopoietic stem/progenitor cell transplantation for eligible patients with an available donor is the only current curative therapy. Other patients may receive immunosuppression, most commonly with anti-thymocyte globulin and cyclosporin. An initial response to immunosuppression is often encouraging, but relapse is common. Supportive care, including management of transfusion requirements and infections, is central to management. Promising new diagnostic tools and emerging therapies will likely transform approaches to this important, chronic and life-threatening condition.

Predicting response to porcine antilymphocyte globulin plus cyclosporine A in children with acquired severe aplastic anemia

BACKGROUND

In severe aplastic anemia (SAA), predictive markers of response to immunosuppressive therapy (IST) of porcine antilymphocyte globulin (pALG) have not been well defined. We investigated whether clinical and laboratory findings before treatment could predict response in a pediatric cohort.

METHODS

In this study, we included 70 newly diagnosed SAA children and treated them with pALG. The response rate was documented during follow-up. The log-rank test compared response rates between the potential predictive factors.

RESULTS

The response rate was 57.1% at 24 months follow-up. In log-rank test, mild disease severity was the most significant predictive marker of better response (P < 0.001); SAA patients with higher absolute reticulocyte count (ARC) and platelet level showed a higher response rate (both P < 0.001). Although insignificantly, elderly children and male sex show better response rate after treatment. The response rate worsened when the time interval before IST was more than 60 days.

CONCLUSION

Modified IST with pALG was suitable for SAA children, and favorable response correlates with mild disease severity was identified. ARC and platelet status also appeared to be a reproducible prognostic model for response rate. IST should be started as soon as possible, given that the response rate worsens as the interval between diagnosis and treatment increases.

Evolution patterns of paroxysmal nocturnal hemoglobinuria clone and clinical implications in acquired bone marrow failure

The paroxysmal nocturnal hemoglobinuria (PNH) clone often presents in acquired bone marrow failure (aBMF), which is involved in more than half of aplastic anemia (AA) cases and about 10%-20% of myelodysplastic syndrome (MDS) cases. PNH clone expansion patterns and clinical implications, however, remain obscure. We conducted a large retrospective study of 457 aBMF patients with positive PNH clones to explore the wide spectrum of clone architecture, evolution patterns, and clinical implications. PNH clone size at diagnosis in AA or MDS was significantly smaller than that in clinical PNH (p < 0.001); the main clone patterns in AA and MDS were granulocyte dominant, with the remaining cases having a granulocyte-erythrocyte balance pattern in clinical PNH. In 131 AA patients at follow-up, there was no obvious difference in response rates between those with the aggressive pattern of clone evolution (73.7%) and those with the stable pattern (81.1%). A quarter of AA patients evolved into clinical hemolysis within a median interval of 11 months. AA cases progressing into clinical hemolysis after immunosuppressive therapy had significantly larger clones (granulocytes: 12.3% vs. 2.6%; erythrocytes: 5.7% vs. 1.3%) at diagnosis and presented mainly an aggressive pattern, especially the granulocyte-erythrocyte aggressive model. Clone sizes reaching 37% for erythrocytes and 28% for granulocytes were indicators of the onset of hemolysis in AA. In conclusion, aBMF patients presented significantly various PNH clone patterns at diagnosis. AA patients with either an aggressive or stable evolution pattern can achieve a response, but patients with an aggressive evolution pattern, especially the granulocyte-erythrocyte aggressive model, tend to evolve into clinical hemolysis.

Response to Immunosuppressive Therapy in Acquired Aplastic Anaemia: Experience of a Tertiary Care Centre from Eastern India

The current study was conducted to assess response to immunosuppressive therapy (IST) in acquired aplastic anaemia (AA). It was a retrospective and prospective observational study. Patients were diagnosed as per standard international guidelines and IST was started as per standard protocol. Patients were followed up at 3 months and 6 months for assessment of response as per published standard guidelines. Total 76 cases were included in the study. The median age of the study population was 36 years with a range of 6-66 years with a male to female ratio of 2.04:1. Most common clinical presentation was pallor followed by bleeding. Commonest type of disease in the study group was severe AA. Among total 76 patients, 32 patients received Atgam and 44 patients received Thymogam. Within 3 months of ATG administration, 4 patients died and 1 patient was lost to follow up. At 3 months, 2 (2.63%) patients were on complete response (CR), 32 (42.10%) patients were in partial response (PR) and 37 (48.68%) patients were on no response (NR). Overall response (OR) at 3 months was 44.73%. At 6 months 5 (6.57%) patients were in CR, 43 (56.57%) patients in PR and 23 (30.26%) patients in NR; the OR was 63.14%. Overall response at 3 months was 44.73% and overall response at 6 months was 63.14%. The study revealed better overall survival for patients with ATGAM treatment than THYMOGAM treatment arm.

The Case for Upfront HLA-Matched Unrelated Donor Hematopoietic Stem Cell Transplantation as a Curative Option for Adult Acquired Severe Aplastic Anemia

The improved success of HLA-matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT) for severe aplastic anemia (SAA) in recent decades has had an impact on the indications for and timing of this treatment modality. In the absence of a matched sibling donor (MSD), historically MUD HSCT was reserved as an option after failure to respond to at least 2 courses of immunosuppressive therapy (IST) in adults with SAA, but with improved outcomes over time, it is now considered following failure to respond to 1 course of IST. Recent national and international studies and guidelines now recommend upfront MUD HSCT as an option for children for whom an MUD is readily available, because outcomes are similar to those for MSD HSCT. Fludarabine-based conditioning and the use of in vivo T cell depletion with antithymocyte globulin or alemtuzumab has been associated with a reported overall survival (OS) of >85% in adult patients undergoing MUD HSCT. However, the recent introduction of eltrombopag for patients with SAA has transformed the treatment landscape, and there is currently much interest in its use with IST as upfront treatment, which showed a high response rate in an early-phase study. The risks of HSCT, especially graft-versus-host disease (GVHD), need to be carefully balanced against the concerns of IST, namely relapse and later clonal evolution to myelodysplastic syndrome (MDS)/acute myelogenous leukemia (AML). In the absence of a current prospective randomized trial comparing these 2 approaches, in this review we examine the evidence supporting consideration of early MUD HSCT in adults with SAA who would have been considered for MSD HSCT but who lack a MSD and for whom an MUD is readily available, especially using an irradiation-free conditioning regimen, with a low risk of GVHD, as another treatment option. This option may be offered to patients to provide them with an informed choice, with the aim of curing disease rather than achieving freedom from disease, relapse-free survival, or OS. Furthermore, understanding the immune signature for the response to IST and the immunologic responses to somatic mutations and clonal progression to MDS/AML may help define the future indications for upfront HSCT and a more precise medical approach to therapy.

ICCS/ESCCA consensus guidelines to detect GPI-deficient cells in paroxysmal nocturnal hemoglobinuria (PNH) and related disorders part 3 - data analysis, reporting and case studies

Over the past several years, a diverse group of physicians and other laboratory scientists have developed various recommendations and guidelines regarding best practices for PNH testing. This manuscript is based on these previous recommendations as well as various other relevant publications of experts in the area of PNH testing. The goal is to provide flow cytometry laboratories with an updated consensus approach to analysis and reporting of PNH results and to address the most common analytical challenges for accurate reporting of this rare disease. A comprehensive case library is included in this section. © 2017 International Clinical Cytometry Society.

Aplastic anemia in children: How good is immunosuppressive therapy?

Aplastic anemia (AA) is an uncommon disorder in children, with hematopoietic stem cell transplant being the 1st line therapy; immunosuppressive therapy (IST) is the alternative therapy and is the most commonly used modality of treatment. There is paucity of data from the developing countries regarding treatment outcome with IST. We aimed to assess the outcome of IST in children with AA. Data for 43 children treated with IST from January 2012 to January 2017 (5 years) were retrieved from clinic records. IST included equine antithymocyte globulin (ATG) along with cyclosporine A. Complete response, partial response and nonresponse was seen in 9 (21%), 14 (32.5%) and 20(46.5%) patients, respectively. The median time to best response in the whole cohort was 19.1 months. However, complete response occurred nearly 2-year post-IST. There was no difference in outcome related to severity of AA, the presence of PNH clone, higher ALC or different available brands of ATG. There was a significantly better rate of response (p value: .03) at 6 months in patients who went on to achieve a CR vs patients who achieved a final PR only. An overall response rate, including partial and complete response, of 53.5% was seen in our cohort with a 3-year OS of 63%. This is not at par to the outcome reported from developed nations. The available brands of ATG were similar in terms of response kinetics as well as survival. A delayed time to complete response with prolonged requirement of cyclosporine therapy was seen in the cohort.

Hematopoietic stem cell transplantation with alpha/beta T-lymphocyte depletion and short course of eculizumab in adolescents and young adults with paroxysmal nocturnal hemoglobinuria

AIM

The main goal is to optimize hematopoietic stem cell transplantation (HSCT) approach among adolescents and young adults with paroxysmal nocturnal hemoglobinuria (PNH) by means of Graft-versus-host disease (GVHD) and post-transplant complications risk lowering.

MATERIALS AND METHODS

We report our experience of HSCT from HLA-matched unrelated donors using TCR alfa/beta and CD19 depletion in 5 pts (1M/4F) with PNH, developed after successful immunosuppressive therapy (IST) of acquired aplastic anemia (AA). Median age of pts at the moment of transplantation was 17,8 years (range 14,5-22,7), median interval from IST to PNH was 4 years (5mo - 6,5 y). In all patients non-severe pancytopenia was present: granulocytes 0,8х109/l (0,8-1,8 х109/l) platelets 106 х109/l (27-143 х109/l) and Hb -78 g/l, median PNH clone size in granulocytes was 94 (range 75-99)%. One pts previously developed sinus thrombosis. Conditioning consisted of thoraco-abdominal irradiation 4-6 Gy, cyclophosphamide 100 mg/kg, fludarabine 150 mg/m2 and anti-thymocyte globulin (ATG) or alemtuzumab. Eculizumab was given from day (-7) till day (+14) (every 7 days, only 4 times). GVHD prophylaxis was tacrolimus ± methotrexate.

RESULTS

Infusedgraft characteristics were: CD34+ - 8,1х106/kg, CD3TCRab·150х103/kg, CD3gd+ - 7,3х106/kg, СD19+ - 221х103/kg, NK -6,4х108/kg. Engraftment was achieved in all 5 pts with a median of 15(12-18) и 13(10-18) days for granulocytes and platelets, respectively. Skin acute GVHD grade I developed in only 1 pt, and subsided with short course of glucocorticoids. CMV reactivation occurred in 1 pt; there were no episodes of Epstein-Barr Virus (EBV) o rAdenovirus (AdV) reactivation. Full donor myeloid chimerism was established in all pts by day +30. Immune reconstitution was delayed until 6 months after transplant but no severe infections occurred. All pts are alive 1,7-5,5 years (med 4 years) after HSCT with normal hematopoiesis and immune function, full donor chimerism and no late sequelae.

CONCLUSION

Transplantation of TCRalfa/beta and CD19 depleted hematopoietic cells from matched unrelated donor after immunoablative conditioning and supported with short course of eculizumab is perfectly safe and efficient technology leading to cure in young patients with PNH.

Bone Marrow as a Source of Cells for Paroxysmal Nocturnal Hemoglobinuria Detection

Objectives

To determine fluorescently labeled aerolysin (FLAER) binding and glycophosphatidylinositol–anchored protein expression in bone marrow (BM) cells of healthy volunteers and patients with paroxysmal nocturnal hemoglobinuria (PNH) detected in peripheral blood (PB); compare PNH clone size in BM and PB; and detect PNH in BM by commonly used antibodies.

Methods

Flow cytometry analysis of FLAER binding to leukocytes and expression of CD55/CD59 in erythrocytes. Analysis of CD16 in neutrophils and CD14 in monocytes in BM.

Results

FLAER binds to all normal BM leukocytes, and binding increases with cell maturation. In PNH, lymphocytic clones are consistently smaller than clones of other BM cells. PNH clones are detectable in mature BM leukocytes with high specificity and sensitivity using common antibodies.

Conclusions

PNH clone sizes measured in mature BM leukocytes and in PB are comparable, making BM suitable for PNH assessment. We further demonstrate that commonly used reagents (not FLAER or CD55/CD59) can reliably identify abnormalities of BM neutrophils and monocytes consistent with PNH cells.

Establishment of a flow cytometry assay for detecting paroxysmal nocturnal hemoglobinuria-type cells specific to patients with bone marrow failure

Minor populations of glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) cells in the peripheral blood may have a prognostic value in bone marrow failure (BMF). Our objective is to establish the optimal flow cytometry (FCM) assay that can discriminate GPI(-) populations specific to BMF from those of healthy individuals. To identify a cut-off that discriminates GPI(-) rare cells from GPI(+) cells, we determined a position of the borderline that separates the GPI(-) from GPI(+) cells on a scattergram by testing more than 30 healthy individuals, such that no GPI(-) dot fell into the upper left quadrant where fluorescein-labeled aerolysin (FLAER)^-CD11b⁺ granulocytes and CD55^-CD59^- glycophorin A⁺ erythrocytes were positioned. This method allowed us to define ≥ 0.003% CD11b⁺FLAER^- granulocytes and ≥ 0.005% glycophorin A⁺CD55^-CD59^- erythrocytes to be specific to BMF patients. Longitudinal cross-validation studies showed minimal (< 0.02%) inter-laboratory differences in the GPI(-) cell percentage. An analysis of 1210 patients with BMF revealed a GPI(-) cell population in 56.3% of patients with aplastic anemia and 18.5% of patients with myelodysplastic syndrome. The GPI(-) granulocyte percentages was 0.003-0.01% in 3.7% of patients. This FCM assay effectively identified an increase in the percentage of GPI(-) rare cells that are specific to BMF patients and allowed different laboratories to accurately detect 0.003-0.01% of pathological GPI(-) cells.

Somatic Mutations in Aplastic Anemia

Aplastic anemia (AA) is an immune-mediated disorder that overlaps closely with clonal disorders, such as myelodysplastic syndrome and paroxysmal nocturnal hemoglobinuria (PNH). PIGA mutations in PNH clones and functional loss of HLA, including structural HLA mutations, likely represent immune escape clones and correlate with response to immunosuppressive therapy (IST). Somatic mutations typical for myeloid malignancies and age-related clonal hematopoiesis are detected in a proportion of AA patients, but their significance is unclear and seems to depend on whether patients are tested at diagnosis or after IST, patient age and ethnicity, and the methodology of molecular testing used.

Diagnosis and Treatment of Aplastic Anemia

OPINION STATEMENT

Acquired aplastic anemia (AA) is a rare, life-threatening bone marrow failure (BMF) disorder that affects patients of all ages and is caused by lymphocyte destruction of early hematopoietic cells. Diagnosis of AA requires a comprehensive approach with prompt evaluation for inherited and secondary causes of bone marrow aplasia, while providing aggressive supportive care. The choice of frontline therapy is determined by a number of factors including AA severity, age of the patient, donor availability, and access to optimal therapies. For newly diagnosed severe aplastic anemia, bone marrow transplant should be pursued in all pediatric patients and in younger adult patients when a matched sibling donor is available. Frontline therapy in older adult patients and in all patients lacking a matched sibling donor involves immunosuppressive therapy (IST) with horse antithymocyte globulin and cyclosporine A. Recent improvements in upfront therapy include encouraging results with closely matched unrelated donor transplants in younger patients and the emerging benefits of eltrombopag combined with initial IST, with randomized studies underway. In the refractory setting, several therapeutic options exist, with improving outcomes of matched unrelated donor and haploidentical bone marrow transplantation as well as the addition of eltrombopag to the non-transplant AA armamentarium. With the recent appreciation of frequent clonal hematopoiesis in AA patients and with the growing use of next-generation sequencing in the clinic, utmost caution should be exercised in interpreting the significance of somatic mutations in AA. Future longitudinal studies of large numbers of patients are needed to determine the prognostic significance of somatic mutations and to guide optimal surveillance and treatment approaches to prevent long-term clonal complications.

Elevated Serum Interleukin-6 Predicts Favorable Response to Immunosuppressive Therapy in Children With Aplastic Anemia

BACKGROUND

Immunosuppressive therapy (IST) is the standard treatment for aplastic anemia (AA) children who lack a sibling donor, but the clinical response rate to IST varies. Predictors of response to IST are valuable for stratifying AA patients and making clinical decisions.

METHODS

The serum interleukin (IL)-6 levels of 41 AA patients were measured at the time of diagnosis and the response rate of the patients to IST was evaluated at 3, 6, and 12 months after IST. Receiver-operator characteristic (ROC) analysis was used to calculate the predictive value of initial IL-6 levels in determining response at 6 months after IST.

RESULTS

The initial IL-6 levels were significant higher in responders than nonresponders at 6 months after IST (211.89 vs. 18.09 pg/mL; P=0.005), using 36.8 pg/mL as a threshold, there were 80% sensitivity and 81% specificity for discriminating responders and nonresponders to IST. Patients with initial high IL-6 level (>36.8 pg/mL) have favorable response rates than those with initial low IL-6 level (<36.8 pg/mL) at 3, 6, and 12 months after IST (P<0.01).

CONCLUSION

High levels of IL-6 at the time of diagnosis predict a favorable response to IST in children with AA and this may be helpful for patient's stratification and clinical decisions.

Standardized high-sensitivity flow cytometry testing for paroxysmal nocturnal hemoglobinuria in children with acquired bone marrow failure disorders: A single center US study

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematopoietic stem cell disorder that has not been well-documented in children, particularly those with acquired bone marrow failure disorders (ABMFD)-acquired aplastic anemia (AAA) and myelodysplastic syndrome (MDS). Therefore, we sought to determine the prevalence of PNH populations in children with ABMFD.

METHODS

PNH testing was performed in children with an ABMFD diagnosis using high sensitivity (≥0.01%) fluorescent aerolysin (FLAER)-based assay according to 2010 International Clinical Cytometry Society (ICCS) PNH Consensus Guidelines and 2012 Practical PNH Guidelines. FLAER/CD64/CD15/CD24/CD14/CD45 and CD235a/CD59 panels were used for white blood cell and red blood cell testing, respectively.

RESULTS

Thirty-seven patients with ABMFD (34 AAA, 3 MDS) were included (17M/20F, age 2-18 years, median 9 years). PNH populations were identified in 17 of 37 (46%) patients. Of the 17 patients with PNH populations identified, 7 were PNH clones (>1% PNH population), and 10 had minor PNH population or rare cells with PNH phenotype (≤1% PNH population).

CONCLUSIONS

This is the first study to use a standardized high-sensitivity FLAER-based flow cytometry assay and the recommended cutoff of 0.01% to identify cells with PNH phenotype in pediatric patients with ABMFD in the United States. The identification of a PNH population in 46% of ABMFD supports the recommendation for high sensitivity PNH testing in children with these disorders. As a less sensitive assay using a cutoff of ≥ 1% PNH population would have missed 10 (27%) patients with minor PNH population or rare cells with PNH phenotype. © 2017 International Clinical Cytometry Society.

T Cell Transcriptomes from Paroxysmal Nocturnal Hemoglobinuria Patients Reveal Novel Signaling Pathways

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder originating from hematopoietic stem cells and is a life-threating disease characterized by intravascular hemolysis, bone marrow (BM) failure, and venous thrombosis. The etiology of PNH is a somatic mutation in the phosphatidylinositol glycan class A gene (PIG-A) on the X chromosome, which blocks synthesis of the glycolipid moiety and causes deficiency in GPI-anchored proteins. PNH is closely related to aplastic anemia, in which T cells mediate destruction of BM. To identify aberrant molecular mechanisms involved in immune targeting of hematopoietic stem cells in BM, we applied RNA-seq to examine the transcriptome of T cell subsets (CD4⁺ naive, CD4⁺ memory, CD8⁺ naive, and CD8⁺ memory) from PNH patients and healthy control subjects. Differentially expressed gene analysis in four different T cell subsets from PNH and healthy control subjects showed distinct transcriptional profiles, depending on the T cell subsets. By pathway analysis, we identified novel signaling pathways in T cell subsets from PNH, including increased gene expression involved in TNFR, IGF1, NOTCH, AP-1, and ATF2 pathways. Dysregulation of several candidate genes (JUN, TNFAIP3, TOB1, GIMAP4, GIMAP6, TRMT112, NR4A2, CD69, and TNFSF8) was validated by quantitative real-time RT-PCR and flow cytometry. We have demonstrated molecular signatures associated with positive and negative regulators in T cells, suggesting novel pathophysiologic mechanisms in PNH. These pathways may be targets for new strategies to modulate T cell immune responses in BM failure.

Recent advances in understanding clonal haematopoiesis in aplastic anaemia

Acquired aplastic anaemia (AA) is an immune-mediated bone marrow failure disorder inextricably linked to clonal haematopoiesis. The majority of AA patients have somatic mutations and/or structural chromosomal abnormalities detected as early as at diagnosis. In contrast to other conditions linked to clonal haematopoiesis, the clonal signature of AA reflects its immune pathophysiology. The most common alterations are clonal expansions of cells lacking glycophosphotidylinositol-anchored proteins, loss of human leucocyte antigen alleles, and mutations in BCOR/BCORL1, ASXL1 and DNMT3A. Here, we present the current knowledge of clonal haematopoiesis in AA as it relates to aging, inherited bone marrow failure, and the grey-zone overlap of AA and myelodysplastic syndrome (MDS). We conclude by discussing the significance of clonal haematopoiesis both for improved diagnosis of AA, as well as for a more precise, personalized approach to prognostication of outcomes and therapy choices.

Nontransplant therapy for bone marrow failure

Nontransplant therapeutic options for acquired and constitutional aplastic anemia have significantly expanded during the last 5 years. In the future, transplant may be required less frequently. That trilineage hematologic responses could be achieved with the single agent eltrombopag in refractory aplastic anemia promotes new interest in growth factors after years of failed trials using other growth factor agents. Preliminary results adding eltrombopag to immunosuppressive therapy are promising, but long-term follow-up data evaluating clonal evolution rates are required before promoting its standard use in treatment-naive disease. Danazol, which is traditionally less preferred for treating cytopenias, is capable of preventing telomere attrition associated with hematologic responses in constitutional bone marrow failure resulting from telomere disease.

Diagnostic screening of paroxysmal nocturnal hemoglobinuria: Prospective multicentric evaluation of the current medical indications

BACKGROUND

Although consensus guidelines have been proposed in 2010 for the diagnostic screening of paroxysmal nocturnal hemoglobinuria (PNH) by flow cytometry (FCM), so far no study has investigated the efficiency of such medical indications in multicentric vs. reference laboratory settings.

METHODS

Here we evaluate the efficiency of consensus medical indications for PNH testing in 3,938 peripheral blood samples submitted to FCM testing in 24 laboratories in Spain and one reference center in Brazil.

RESULTS

Overall, diagnostic screening based on consensus medical indications was highly efficient (14% of PNH⁺ samples) both in the multicenter setting in Spain (10%) and the reference laboratory in Brazil (16%). The highest frequency of PNH⁺ cases was observed among patients screened because of bone marrow (BM) failure syndrome (33%), particularly among those with aplastic anemia (AA; 45%) and to a less extent also a myelodysplastic syndrome (MDS; 10%). Among the other individuals studied, the most efficient medical indications for PNH screening included: hemolytic anemia (19%), hemoglobinuria (48%) and unexplained cytopenias (9%). In contrast, only a minor fraction of the patients who had been submitted for PNH testing because of unexplained thrombosis in the absence of cytopenia, were positive (0.4%).

CONCLUSIONS

In summary, our results demonstrate that the current medical indications for PNH screening by FCM are highly efficient, although improved screening algorithms are needed for patients presenting with thrombosis and normal blood cell counts. © 2016 International Clinical Cytometry Society.