Aplastic Anemia: Management of Adult Patients

A multicentre ambispective observational study into the incidence and clinical management of aplastic anaemia in Spain (IMAS study)

Aplastic anemia (AA) is a rare, life-threatening hematological disease, with a poorly defined incidence. As the data available on AA varies substantially worldwide, a multicenter, ambispective, observational study was carried out between 2010 and 2019 to assess the incidence, clinical management and survival of AA at seven Spanish hospitals. The incidence of AA was 2.83 per million inhabitants per year, consistent with that reported previously in Europe, with a median age at diagnosis of 61 years-old (range 12-86), and a similar number of males and females. The initial diagnosis was severe or very severe AA in 55.8% of cases and 93.7% required transfusion. The most frequent first line therapy was anti-thymocyte globulin (ATG) plus cyclosporin A (CsA, 44.2%), followed by other CsA-based regimes (46.3%), with hematopoietic stem cell transplantation an infrequent 1st line therapy. The 6-month response rate was 68.2%, which then increased over a median follow-up of 3.9 years. The 5-year overall survival (5OS) was 73.6%, similar in severe (78.6%) and very severe AA patients (74.6%) but lower in moderate AA (MAA) patients (68.4%). The 5OS was 100% in 0-25 year-old patients but dropping to 58.3% in patients ≥ 60 years-old. At the last contact, 75.8% of the patients were alive. In conclusion, the incidence, characteristics and management of AA in our study are consistent with that reported previously. In terms of survival, although the global long-term OS rate was good, there is room for improvement, particularly in older patients. Finally, what appears to be a worse long-term survival of MAA patients, as reported previously, reinforces the importance of not underestimating this condition when diagnosed as MAA.

Better Failure-Free Survival and Graft-versus-Host Disease-Free/Failure Free Survival with Fludarabine-Based Conditioning in Stem Cell Transplantation for Aplastic Anemia in Children

BACKGROUND

This study aimed to assess the outcome of stem cell transplantation (SCT), including overall survival (OS), failure-free survival (FFS) and graft-versus-host disease (GvHD)-free/failure-free survival (GFFS), and to analyze prognostic factors in children with aplastic anemia (AA).

METHODS

From 1991 to 2018, 43 allogeneic SCT recipients were enrolled in the study to investigate the demographic characteristics, survival outcomes and prognostic factors.

RESULTS

With the median follow-up of 7.1 years, the estimated 10-year OS, FFS, GFFS were 86.0%, 60.5%, and 51.2%, respectively. Matched related donors (MRD, n = 28) showed better 10-year OS than unrelated donors (n = 15) (96.4% vs. 66.7%; P = 0.006). Engraftment failure was seen in 13 patients (30.2%). Donor-type aplasia was seen in 13.8% (4/29) after fludarabine (Flu)-based conditioning (Flu-group), while in 42.6% (6/14) after cyclophosphamide (Cy)-based regimen (Cy-group) (P = 0.035). Six patients died. The 10-year OS in Cy-group was 92.9% (n = 14, all MRD), while that of Flu-group was 82.1% (n = 29; P = 0.367). But Flu-group tended to have better FFS and GFFS than Cy-group, although Flu-group had less MRDs (41.4% vs. 100%; P = 0.019), and higher proportion of previous immunosuppressive treatment (IST; 62% vs. 21.4%, P = 0.012). In MRD transplants, OS was similar between Flu-group (100%, n = 14) and Cy-group (92.9%, n = 14), while FFS (100.0% vs. 42.9%; P = 0.001) and GFFS (85.7% vs. 35.7%; P = 0.006) were significantly better in Flu-group. Stem cell sources, irradiation in the conditioning, and method of GvHD prophylaxis did not significantly influence the outcome.

CONCLUSION

This study reviewed SCT outcomes for pediatric AA with changes of transplant strategies over the last 25 years. The FFS and GFFS were higher in Flu-group than in Cy-group, especially in matched related transplantation. Graft failure including donor-type aplasia remains troublesome even with Flu-based conditioning. Further refinement of transplant strategies to ensure better quality-of-life should be pursued.

Type I IFNs Act upon Hematopoietic Progenitors To Protect and Maintain Hematopoiesis during Pneumocystis Lung Infection in Mice

Although acquired bone marrow failure (BMF) is considered a T cell-mediated autoimmune disease, few studies have considered contributing roles of innate immune deviations following otherwise innocuous infections as a cause underlying the immune defects that lead to BMF. Type I IFN signaling plays an important role in protecting hematopoiesis during systemic stress responses to the opportunistic fungal pathogen Pneumocystis. During Pneumocystis lung infection, mice deficient in both lymphocytes and type I IFN receptor (IFrag(-/-)) develop rapidly progressing BMF associated with accelerated hematopoietic cell apoptosis. However, the communication pathway eliciting the induction of BMF in response to this strictly pulmonary infection has been unclear. We developed a conditional-null allele of Ifnar1 and used tissue-specific induction of the IFrag(-/-) state and found that, following Pneumocystis lung infection, type I IFNs act not only in the lung to prevent systemic immune deviations, but also within the progenitor compartment of the bone marrow to protect hematopoiesis. In addition, transfer of sterile-filtered serum from Pneumocystis-infected mice as well as i.p. injection of Pneumocystis into uninfected IFrag(-/-) mice induced BMF. Although specific cytokine deviations contribute to induction of BMF, immune-suppressive treatment of infected IFrag(-/-) mice ameliorated its progression but did not prevent loss of hematopoietic progenitor functions. This suggested that additional, noncytokine factors also target and impair progenitor functions; and interestingly, fungal β-glucans were also detected in serum. In conclusion, our data demonstrate that type 1 IFN signaling protects hematopoiesis within the bone marrow compartment from the damaging effects of proinflammatory cytokines elicited by Pneumocystis in the lung and possibly at extrapulmonary sites via circulating fungal components.

Antibodies in the treatment of aplastic anemia

Antibodies have been the cornerstone of treatment of acquired aplastic anemia for more than 25 years. Treatment with antithymocyte globulin (ATG) is considered pivotal and the addition of cyclosporine improves the overall response rate. This antibody is heterogeneous and horse ATG is apparently more effective than rabbit ATG. Several issues remain unsolved in relation to the combination of ATG and cyclosporine: cost, toxicity and late clonal disorders. In recent years, alternative immunosuppressive therapy has been proposed and new antibodies have emerged: porcine ATG, alemtuzumab, daclizumab, and rituximab. Experience with these antibodies is limited to a few studies with alemtuzumab being the most promising, but the results are interesting and provocative. More studies are needed to find the perfect antibody.

Aplastic anemia: immunosuppressive therapy in 2010

Acquired aplastic anemia (AA) is the typical bone marrow failure syndrome characterized by an empty bone marrow; an immune-mediated pathophysiology has been demonstrated by experimental works as well as by clinical observations. Immunusuppressive therapy (IST) is a key treatment strategy for aplastic anemia; since 20 years the standard IST for AA patients has been anti-thymocyte globuline (ATG) plus cyclosporine A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after IST remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. Here we review the state of the art of IST for AA in 2010, focusing on possible strategies to improve current treatments. We also discuss very recent data which question the equality of different ATG preparations, leading to a possible reconsideration of the current standards of care for AA patients.

Immunosuppressive therapies in the management of immune-mediated marrow failures in adults: where we stand and where we are going

Immunosuppression is a key treatment strategy for aplastic anaemia (AA) and the related immune-mediated bone marrow failure syndromes (BMFS). For the last 20 years the standard immunosuppressive regimen for AA patients has been anti-thymocyte globulin (ATG) plus ciclosporin A (CyA), which results in response rates ranging between 50% and 70%, and even higher overall survival. However, primary and secondary failures after immunosuppressive therapy remain frequent, and to date all attempts aiming to overcome this problem have been unfruitful. This article reviews the state of the art of current immunosuppressive therapies for AA, focusing on open questions linked to standard immunosuppressive treatment, and on experimental immunosuppressive strategies which could lead to future improvement of current treatments. Specific immunosuppressive strategies employed for other BMFS, such as lineage-restricted marrow failures, myelodysplastic syndromes and large granular lymphocyte leukaemia-associated cytopenias, are also briefly discussed.

A hospital-based case control study of aplastic anemia in Shanghai, China

We report results of a hospital-based case control study of 137 consecutive patients diagnosed with aplastic anemia (AA) in participating hospitals over a 4-year period. Diagnoses were made by a single laboratory, subjects were age- and gender-matched to two controls and interviewed concerning previous disease, work histories and exposures to potential etiologic agents. Analysis was conducted on two distinct subgroups: severe aplastic anemia (SAA) and moderate aplastic anemia (MAA). In univariate regression models, the strongest associations were observed for exposure to benzene and SAA (OR=3.12, 95% CI=1.12-8.65) and life on a farm and MAA (OR=3.08, 95% CI=1.44-6.56). Benzene exposure did not show a strong dose-response relationship with either subtype. When accounting for all of the potential confounders we considered in conditional regression models, the previous relationships persisted. Other explanatory variables included hair-dye use for MAA and farm exposures, such as livestock for SAA, although most of these additional variables fell just short of statistical significance. Adjusted R-squared values were only 10% for each subtype, leaving 90% of AA occurrence unexplained. Our results suggest that: (a) benzene exposure is more strongly related to SAA than MAA, (b) farm and livestock exposures are related to both forms of AA, confirming some previous results, and (c) a large percentage of AA remains unexplained, which may indicate that individual susceptibility has a major influence on AA occurrence.

Paroxysmal nocturnal hemoglobinuria: natural history of disease subcategories

The natural history of paroxysmal nocturnal hemoglobinuria (PNH) clinical subcategories (classic PNH and aplastic anemia [AA]/PNH syndrome) is still unknown. We retrospectively studied 460 PNH patients diagnosed in 58 French hematologic centers from 1950 to 2005. The median (SE) follow-up time was 6.8 (0.5) years. The median survival time (SE) was 22 (2.5) years. We identified 113 patients with classic PNH, 224 patients with AA-PNH syndrome, and 93 (22%) intermediate patients who did not fit within these 2 categories. At presentation, classic PNH patients were older, with more frequent abdominal pain and displayed higher levels of GPI-AP–deficient granulocytes. A time-dependent improved survival was observed. In classic PNH, diagnoses before 1986 (hazard ratio [HR]: 3.6; P = .01) and increasing age (P < .001) were associated with worse survival prognoses, whereas use of androgens within the first year after diagnosis was protective (HR, 0.17; P = .01). Transfusions before 1996 (HR, 2.7; P = .007) led to lower survival rates in patients with AA-PNH syndrome, whereas immunosuppressive treatment was associated with better outcomes (HR, 0.33; P = .03). Evolution to thrombosis affected survival in both subcategories (classic PNH: HR, 7.8 [P < .001]; AA-PNH syndrome: HR, 33.0 [P < .001]). Evolution to bicytopenia or pancytopenia for classic PNH (HR, 7.3, P < .001) and malignancies for AA-PNH syndrome (HR, 48.8; P < .001) were associated with worse outcomes. Although clinical presenta-tion and prognosis factors are different, classic PNH and AA-PNH syndrome present roughly similar outcomes, affected mainly by complications.

Complete hematopoietic recovery after continuous iron chelation therapy in a patient with severe aplastic anemia with secondary hemochromatosis

A 16-yr-old male patient with hemochromatosis due to multiple packed red blood cell transfusions was referred to our emergency center for the treatment of severe aplastic anemia and dyspnea. He was diagnosed with aplastic anemia at 11-yr of age. He had received continuous transfusions because an HLA-matched marrow donor was unavailable. Following a continuous, approximately 5-yr transfusion, he was noted to develop hemochromatosis. He had a dilated cardiomyopathy and required diuretics and digitalis, multiple endocrine and liver dysfunction, generalized bleeding, and skin pigmentation. A total volume of red blood cell transfusion before deferoxamine therapy was about 96,000 mL. He received a regular iron chelation therapy (continuous intravenous infusion of deferoxamine, 50 mg/kg/day for 5 days q 3-4 weeks) for approximately seven years after the onset of multiple organ failures. His cytopenia and organ dysfunctions began to be gradually recovered since about 2002, following a 4-yr deferoxamine treatment. He showed completely normal ranges of peripheral blood cell counts, heart size, and liver function two years ago. He has not received any transfusions for the last four years. This finding suggests that a continuous deferoxamine infusion may play a role in the immune regulation in addition to iron chelation effect.

Making therapeutic decisions in adults with aplastic anemia

The management of adults presenting with aplastic anemia (AA) requires careful exclusion of other causes of bone marrow failure. Late-onset inherited forms of AA may present in adulthood with subclinical disease. Recent long-term studies of HLA identical sibling donor BMT show excellent survival for patients under the age of 40 years, but chronic graft-versus-host disease (GVHD) is still a major problem, impacting on quality of life. Recent improvements in outcome after matched unrelated donor BMT may reflect better donor matching and use of reduced intensity conditioning regimens. For patients treated with immunosuppressive therapy (IST), antithymocyte globulin (ATG) and cyclosporin (CSA) remain the standard regimen with excellent overall survival but less impressive failure-free survival due to nonresponse, relapse and later clonal disorders. The benefit of adding granulocyte colony-stimulating factor (G-CSF) to ATG and CSA is unclear and being assessed in a further prospective European study. Patients who are refractory to conventional IST and currently ineligible for BMT represent difficult management problems. For these patients, new approaches to transplantation are being evaluated, such as fludarabine-based conditioning regimens and the potential use of double umbilical cord blood transplants, but there is a need for new immunosuppressive agents. Improved supportive care is likely to be a major factor in improved outcome of all AA patients whether treated with IST or BMT. Robust predictive factors for response to IST are needed to help in decision making at diagnosis and to help justify exploring novel approaches to therapy.