Are mild/moderate acquired idiopathic aplastic anaemia and low-risk myelodysplastic syndrome one or two diseases or both and how should it/they be treated?

Clinical impact and characteristics of erythroid dysplasia in adult aplastic anaemia: Results from a multicentre registry

Morphological dysplasia in haematopoietic cells, defined by a 10% threshold in each lineage, is one of the diagnostic criteria for myelodysplastic neoplasms. Dysplasia limited to the erythroid lineage has also been reported in some cases of aplastic anaemia (AA); however, its significance remains unclear. We herein examined the impact of erythroid dysplasia on immunosuppressive therapy responses and survival in AA patients. The present study included 100 eligible AA patients without ring sideroblasts. Among them, 32 had dysplasia in the erythroid lineage (AA with minimal dysplasia [mini-D]). No significant sex or age differences were observed between AA groups with and without erythroid dysplasia. In severe/very severe AA and non-severe AA patients, a response to anti-thymocyte globulin + ciclosporin within 12 months was observed in 80.0% and 60.0% of AA with mini-D and 42.9% and 90.0% of those without dysplasia, with no significant difference (p = 0.29 and p = 0.24 respectively). Overall survival and leukaemia-free survival did not significantly differ between the groups. Collectively, the present results indicate that the presence of erythroid dysplasia did not significantly affect clinical characteristics or outcomes in AA patients, suggesting that its presence in AA is acceptable. Therefore, erythroid dysplasia should not exclude an AA diagnosis.

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.

When inflammatory stressors dramatically change, disease phenotypes may transform between autoimmune hematopoietic failure and myeloid neoplasms

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome are paradigms of autoimmune hematopoietic failure (AHF). Myelodysplastic syndrome and acute myeloid leukemia are unequivocal myeloid neoplasms (MNs). Currently, AA is also known to be a clonal hematological disease. Genetic aberrations typically observed in MNs are detected in approximately one-third of AA patients. In AA patients harboring MN-related genetic aberrations, a poor response to immunosuppressive therapy (IST) and an increased risk of transformation to MNs occurring either naturally or after IST are predicted. Approximately 10%-15% of patients with severe AA transform the disease phenotype to MNs following IST, and in some patients, leukemic transformation emerges during or shortly after IST. Phenotypic transformations between AHF and MNs can occur reciprocally. A fraction of advanced MN patients experience an aplastic crisis during which leukemic blasts are repressed. The switch that shapes the disease phenotype is a change in the strength of extramedullary inflammation. Both AHF and MNs have an immune-active bone marrow (BM) environment (BME). In AHF patients, an inflamed BME can be evoked by infiltrated immune cells targeting neoplastic molecules, which contributes to the BM-specific autoimmune impairment. Autoimmune responses in AHF may represent an antileukemic mechanism, and inflammatory stressors strengthen antileukemic immunity, at least in a significant proportion of patients who have MN-related genetic aberrations. During active inflammatory episodes, normal and leukemic hematopoieses are suppressed, which leads to the occurrence of aplastic cytopenia and leukemic cell regression. The successful treatment of underlying infections mitigates inflammatory stress-related antileukemic activities and promotes the penetration of leukemic hematopoiesis. The effect of IST is similar to that of treating underlying infections. Investigating inflammatory stress-powered antileukemic immunity is highly important in theoretical studies and clinical practice, especially given the wide application of immune-activating agents and immune checkpoint inhibitors in the treatment of hematological neoplasms.

Long-term outcomes of aplastic anemia with cytogenetic abnormalities at diagnosis

OBJECTIVES

To elucidate the clinical characteristics of AA patients with cytogenetic abnormalities.

METHODS

We retrospectively screened 30 patients (30/1206, 2.5%) with cytogenetic abnormalities from 1206 patients with severe and very severe AA who received immunosuppressive therapy (IST) during the years 2012-2019.

RESULTS

The most common abnormalities were trisomy 8 (+8, 10/30, 33.3%) and loss of Y (-Y, 8/30, 26.7%). The abnormal clones disappeared 6 months after IST in 14 patients and sustained in 12 patients. Patients with sustained abnormal clones had a lower hematologic response at 6 months after IST than the disappeared (33.3% vs. 64.3%, p = .116). The hematologic response after IST, 5-year overall survival, 5-year event-free survival, myelodysplastic syndrome or acute myeloid leukemia transformation in AA patients with cytogenetic abnormalities were not statistically different from those in normal cytogenetic patients.

CONCLUSION

For AA patients with chromosome abnormalities but ineligible for hematopoietic stem cell transplant, IST is effective and appropriate as first-line treatment.

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

Uncertainty and the inconvenient facts of diagnosis

One common contemporary usage of the term "diagnostic uncertainty" is to refer to cases for which a diagnosis is not, or cannot, be applied to the presenting case. This is a paradoxical usage, as the absence of diagnosis is often as close to a certainty as can be a human judgement. What makes this sociologically interesting is that it represents an "epistemic defence," or a means of accounting for a failure of medicine's explanatory system. This system is based on diagnosis, or the classification of individual complaints into recognizable diagnostic categories. Diagnosis is pivotal to medicine's epistemic setting, for it purports to explain illness via diagnosis, and yet is not always able to do so. This essay reviews this paradoxical use, and juxtaposes it to historical explanations for non-diagnosable illnesses. It demonstrates how representing non-diagnosis as uncertainty protects the epistemic setting by positioning the failure to locate a diagnosis in the individual, rather than in the medical paradigm.

Pretreatment Immature Platelet Fraction as a Surrogate of Reticulated Platelets Predicts the Response to Corticosteroids in Adults with Immune Thrombocytopenia

OBJECTIVES

Reticulated platelets circulating in the blood reflect megakaryopoietic activity and platelet turnover and can be automatically and low-invasively measured as the immature platelet fraction (IPF) using a Sysmex XN hematocytometer. The present study retrospectively investigated whether or not the IPF can predict the treatment response to corticosteroids in adult patients with primary immune thrombocytopenia (ITP).

METHODS

Forty-six patients who had been newly diagnosed with primary treatment-naïve ITP and started treatment with corticosteroids were analyzed.

RESULTS

Among the 46 primary ITP patients, 33 (72%) responded to the treatment and 13 (28%) did not. The percentage of IPF (IPF%) among the nonresponders was significantly lower than that of the responders (6.6 vs. 16.0%; p < 0.001). In the receiver operating characteristics analysis, the optimum IPF% cut-off value for predicting the treatment response was 12%, with a specificity of 85% and a sensitivity of 76%.

CONCLUSIONS

Our findings thus suggest that measuring the IPF% as a surrogate of reticulated platelets is useful to identify patients likely to respond to corticosteroids.

18F-FLT PET/MRI for bone marrow failure syndrome-initial experience

Background

Bone marrow failure syndrome (BMFS) is a heterogeneous group of disorders associated with single- or multiple-lineage cytopenia and failure of normal hematopoiesis. We assessed the feasibility of integrated PET/MRI with 3′-deoxy-3′-¹⁸F-fluorothymidine (¹⁸F-FLT) to assess the pathophysiology of whole-body bone marrow for the diagnosis and monitoring of BMFS. Twenty-five consecutive patients with BMFS underwent a pre-treatment ¹⁸F-FLT PET/MRI scan. They included 7 patients with aplastic anemia (AA), 16 with myelodysplastic syndrome (MDS), and 2 with myeloproliferative neoplasms (MPNs), primary myelofibrosis (MF), and secondary [post-essential thrombocythemia (post-ET)] MF. Two of the seven AA patients underwent a post-treatment scan. Eight of the 16 MDS patients who exhibited decreased ¹⁸F-FLT uptake in the pelvis were considered to have hypoplastic MDS (hypo-MDS). ¹⁸F-FLT PET and diffusion-weighted imaging (DWI) were visually and quantitatively evaluated.

Results

The ¹⁸F-FLT uptake in the ilium was strongly correlated with bone marrow cellularity based on biopsy samples (ρ = 0.85). AA patients exhibited heterogeneously decreased uptake of ¹⁸F-FLT according to disease severity. Multiple ¹⁸F-FLT foci were observed in the proximal extremities, and they were in the central skeleton in severe AA patients. Post-treatment ¹⁸F-FLT PET scans of severe AA patients reflected the response of hematopoietic activity to treatment. MDS patients had marked ¹⁸F-FLT uptake in the central skeleton and proximal extremities, whereas hypo-MDS patients had heterogeneously decreased uptake, similar to that of non-severe AA patients. ¹⁸F-FLT PET and DWI were unable to predict the progression to leukemia for both MDS and hypo-MDS patients. A primary MF patient had slightly decreased ¹⁸F-FLT uptake in the central skeleton, but marked expansion of bone marrow activity to the distal extremities and high uptake of tracer in the extremely enlarged spleen (extramedullary hematopoiesis). In contrast, a secondary (post-ET) MF patient demonstrated marked bone marrow uptake, reflecting the hypercellular marrow with fibrosis. DWI revealed diffusely high signal intensities in both the primary and secondary MF patients.

Conclusion

¹⁸F-FLT PET can be used to noninvasively assess whole-body bone marrow proliferative activity and DWI may reflect the different aspects of bone marrow pathophysiology from ¹⁸F-FLT PET. ¹⁸F-FLT PET/MRI is useful for the diagnosis and monitoring of BMFS, except for the differentiation between non-severe AA and hypo-MDS, and the prediction of progression to leukemia.

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.