Rabbit antithymocyte globulin dose does not affect response or survival as first-line therapy for acquired aplastic anemia: a multicenter retrospective study

Guidelines for the diagnosis and management of adult aplastic anaemia: A British Society for Haematology Guideline

Pancytopenia with hypocellular bone marrow is the hallmark of aplastic anaemia (AA) and the diagnosis is confirmed after careful evaluation, following exclusion of alternate diagnosis including hypoplastic myelodysplastic syndromes. Emerging use of molecular cyto-genomics is helpful in delineating immune mediated AA from inherited bone marrow failures (IBMF). Camitta criteria is used to assess disease severity, which along with age and availability of human leucocyte antigen compatible donor are determinants for therapeutic decisions. Supportive care with blood and platelet transfusion support, along with anti-microbial prophylaxis and prompt management of opportunistic infections remain key throughout the disease course. The standard first-line treatment for newly diagnosed acquired severe/very severe AA patients is horse anti-thymocyte globulin and ciclosporin-based immunosuppressive therapy (IST) with eltrombopag or allogeneic haemopoietic stem cell transplant (HSCT) from a matched sibling donor. Unrelated donor HSCT in adults should be considered after lack of response to IST, and up front for young adults with severe infections and a readily available matched unrelated donor. Management of IBMF, AA in pregnancy and in elderly require special attention. In view of the rarity of AA and complexity of management, appropriate discussion in multidisciplinary meetings and involvement of expert centres is strongly recommended to improve patient outcomes.

The future of aplastic anemia treatment in Brazil: Lessons learned for global hematology

Aplastic anemia (AA) is a rare serious hematologic disorder caused by hematopoietic stem cell failure in maintaining hematopoiesis. AA is virtually fatal if not treated, and diagnosis and therapy require extensive hematologic infrastructure. Academic medical centers in Brazil have continuously and significantly contributed to diagnostic tools and therapy development, from novel transplant strategies to drug combinations and implementation science in the national public health system. In the present review, we discuss how the collaborative effort among academic centers in hematology has contributed to improving health care for patients with aplastic anemia. We also discuss what needs are still unmet and how to overcome these challenges.

First-line immunosuppressive therapy with rATG and CsA for severe aplastic anemia: 15 years' experience

Rabbit antithymocyte globulin (rATG) instead of horse ATG has been used for severe aplastic anemia (SAA) patients in China. This study aimed to investigate the hematologic responses and long-term overall survival (OS) outcomes in SAA patients who received rATG and cyclosporine as first-line immunosuppressive therapy. We analyzed data of 542 SAA patients treated with this therapy between 2005 and 2019. The median age was 20 (range, 2-80) years, and the median follow-up time was 45.5 (range, 0.1-191.4) months. The early mortality rate was 3.9%. The overall response rates (ORRs) were 40.2%, 56.1%, and 62.4% at 3, 6, and 12 months, respectively. The 6- and 12-month ORR of patients treated with 3 mg/kg/d of rATG in 2015-2019 seemed higher than that of patients treated with 3.5-3.75 mg/kg/day in 2005-2014 (60.2% vs. 54.9%, P = 0.30 and 69.9% vs. 60.1%, P = 0.049, respectively). The 10-year cumulative incidences of relapse and clonal evolution were 10.6 ± 2.9% and 7.5 ± 1.5%, respectively. The 10-year OS rate and event-free survival rate were 80.1 ± 2.1% and 75.6 ± 3.7%, respectively. Age, disease severity, treatment periods, and the interval from diagnosis to IST were independent predictors of OS. In conclusion, 3 mg/kg/day rATG is effective as first-line treatment for SAA.

New Trends of Nontransplant therapy for Acquired Aplastic Anemia

Aplastic anemia (AA) is a hematological disease that is characterized by pancytopenia and hypofunctional bone marrow hematopoiesis. Patients with AA are treated with either immunosuppressive therapy (IST) using anti-thymocyte globulin (ATG) and Cyclosporine (CsA) or hematopoietic stem cell transplantation (HSCT), if a matched donor is available. The standard IST regimen for AA patients which results in response rates up to 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. The nontransplant therapeutic options for AA have significantly expanded during the last few years. Here, we review the new trends of nontransplant therapy for AA and summarize the current therapeutic effect of AA.

Special issues related to the diagnosis and management of acquired aplastic anemia in countries with restricted resources, a report on behalf of the Eastern Mediterranean blood and marrow transplantation (EMBMT) group and severe aplastic anemia working party of the European Society for blood and marrow transplantation (SAAWP of EBMT)

Aplastic anemia is a relatively rare but potentially fatal disorder, with a reported higher incidence in developing countries in comparison to the West. There are significant variations in epidemiological as well as etiological factors of bone marrow failure syndromes in the developing countries in comparison to the developed world. Furthermore, the management of bone marrow failure syndromes in resource constraint settings has significant challenges including delayed diagnosis and referral, limited accessibility to healthcare facilities, treatment modalities as well as limitations related to patients who require allogeneic stem cell transplantation. Here we will provide a review of the available evidence related to specific issues of aplastic anemia in the developing countries and we summarize suggested recommendations from the Eastern Mediterranean blood and bone marrow transplantation (EMBMT) group and the severe aplastic anemia working party of the European Society of blood and marrow transplantation (SAAWP of EBMT) related to the diagnosis and therapeutic options in countries with restricted resources.

Acquired severe aplastic anaemia: how medical therapy evolved in the 20th and 21st centuries

The progress in aplastic anaemia (AA) management is one of success. Once an obscure entity resulting in death in most affected can now be successfully treated with either haematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). The mechanisms that underly the diminution of haematopoietic stem cells (HSCs) are now better elucidated, and include genetics and immunological alterations. Advances in supportive care with better antimicrobials, safer blood products and iron chelation have greatly impacted AA outcomes. Working somewhat 'mysteriously', anti-thymocyte globulin (ATG) forms the base for both HSCT and IST protocols. Efforts to augment immunosuppression potency have not, unfortunately, led to better outcomes. Stimulating HSCs, an often-sought approach, has not been effective historically. The thrombopoietin receptor agonists (Tpo-RA) have been effective in stimulating early HSCs in AA despite the high endogenous Tpo levels. Dosing, timing and best combinations with Tpo-RAs are being defined to improve HSCs expansion in AA with minimal added toxicity. The more comprehensive access and advances in HSCT and IST protocols are likely to benefit AA patients worldwide. The focus of this review will be on the medical treatment advances in AA.

[Diagnosis and Therapy of aplastic anemia - update 2021]

The landscape of aplastic anemia (AA) is changing as new therapeutic options become available and sophistic diagnostics enable us to decipher various subgroups of bone marrow failure syndromes (BMFS) such as telomeropathies and other constitutional diseases with manifestations beyond childhood.This article briefly summarizes developments of the last few years with potential clinical impact and puts it into perspective. Focus is given to the growing list of inherited BMFS and the need to e. g. screen patients at all ages for telomeropathies before initiation of treatment as part of routine evaluation of AA. The usage of next generation sequencing (NGS) to differentiate between AA and malignancies such as myelodysplatic syndrome (MDS) and the need to watch out for potential clonal evolution during and after treatment is also briefly discussed. Recent data on combinations of immunosuppressive therapy (IST) with thrombopoietin receptor agonists (TRA) for patients with severe AA as well as newer data with TRA mono-therapy for patients with moderate AA are presented. Finally the importance of supportive measures, structures and quality of life aspects are highlighted.

Eltrombopag preferentially expands haematopoietic multipotent progenitors in human aplastic anaemia

Eltrombopag has been added to first-line treatment of immune aplastic anaemia (AA), resulting in higher responses. We analysed marrow samples of AA patients who responded to immunosuppressive therapy (IST) alone or in combination with eltrombopag for the composition of the haematopoietic stem and progenitor cell (HSPC) compartment. The number of CD34⁺ cells and multipotent progenitors was higher in patients treated with eltrombopag (P < 0·005; P < 0·05; respectively), but not the number of stem cells. No aberrant phenotype was observed. These results indicate that eltrombopag augments CD34⁺ cells in vivo and preferentially expands multipotent progenitors, but not stem cells.

Long-term outcome of a randomized controlled study in patients with newly diagnosed severe aplastic anemia treated with antithymocyte globulin and cyclosporine, with or without granulocyte colony-stimulating factor: a Severe Aplastic Anemia Working Party Trial from the European Group of Blood and Marrow Transplantation

This follow-up study of a randomized, prospective trial included 192 patients with newly diagnosed severe aplastic anemia receiving antithymoglobulin and cyclosporine, with or without granulocyte colony-stimulating factor (G-CSF). We aimed to evaluate the long-term effect of G-CSF on overall survival, event-free survival, probability of secondary myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML), clinical paroxysmal nocturnal hemoglobinuria, relapse, avascular osteonecrosis and chronic kidney disease. The median follow-up was 11.7 years (95% CI, 10.9-12.5). The overall survival rate at 15 years was 57±12% in the group given G-CSF and 63±12% in the group not given G-CSF (P=0.92); the corresponding event-free survival rates were 24±10% and 23±10%, respectively (P=0.36). In total, 9 patients developed MDS or AML, 10 only a clonal cytogenetic abnormality, 7 a solid cancer, 18 clinical paroxysmal nocturnal hemoglobinuria, 8 osteonecrosis, and 12 chronic kidney disease, without any difference between patients treated with or without G-CSF. The cumulative incidence of MDS, AML or isolated cytogenetic abnormality at 15 years was 8.5±3% for the G-CSF group and 8.2±3% for the non-G-CSF group (P=0.90). The cumulative incidence of any late event including myelodysplastic syndrome or acute myeloid leukemia, isolated cytogenetic abnormalities, solid cancer, clinical paroxysmal nocturnal hemoglobinuria, aseptic osteonecrosis, chronic kidney disease and relapse was 50±12% for the G-CSF group and 49±12% for the non-G-CSF group (P=0.65). Our results demonstrate that it is unlikely that G-CSF has an impact on the outcome of severe aplastic anemia; nevertheless, very late events are common and eventually affect the prognosis of these patients, irrespectively of their age at the time of immunosuppressive therapy (NCT01163942).

Activity of eltrombopag in severe aplastic anemia

Since the approval of horse antithymocyte globulin (ATG) decades ago, there was a long hiatus in therapies with activity in severe aplastic anemia (SAA). This scenario changed in 2014 when eltrombopag, a thrombopoietin receptor agonist, was approved for SAA after an insufficient response to initial immunosuppressive therapy (IST). The basis for this approval was the observation of single-agent activity of eltrombopag in this patient population, where 40% to 50% recovered blood counts at times involving >1 lineage. The achievement of transfusion independence confirmed the clinical benefit of this approach. Increase in marrow cellularity and CD34+ cells suggested a recovery to a more functioning bone marrow. Further in its development, eltrombopag was associated with standard horse ATG plus cyclosporine in first line, producing increases in overall (at about 90%) and complete response rates (at about 40%) and leading to transfusion independence and excellent survival. Interestingly, best results were observed when all drugs were started simultaneously. The cumulative incidence of clonal cytogenetic abnormalities to date has compared favorably with the vast experience with IST alone in SAA. Longer follow-up will help in define these long-term risks. In this review, the development of eltrombopag in SAA will be discussed.

Immunosuppressive therapy with rabbit antithymocyte globulin therapy for acquired aplastic anemia: a multi-institutional retrospective study in Japanese adult patients

We retrospectively analyzed efficacy and safety of therapy with rabbit antithymocyte globulin (rATG) in combination with cyclosporine A (CsA) in 30 Japanese adult patients with acquired aplastic anemia (AA) in the Kyoto Clinical Hematology Study Group. The median observation period was 31 months and the median age of the patients was 54 years. The objective response rates (ORRs) to rATG plus CsA increased over time until 18 months after the start of treatment; the rate of achievement of better than partial response at 18 months was 66.7%. The 2-year overall survival (OS) rate was 79% in all patients. In eight patients aged ≥ 75 years old, the ORR was 62.5% and the 2-year OS rate of 50% was not significantly inferior to that in patients aged ≤ 74 years old. The overall mortality rate was 16.7% in our cohort, while the mortality rate in patients aged ≥ 75 years old was 37.5%, which was higher than that in patients aged ≤ 74 years old (9.1%), although the difference was not statistically significant. Collectively, rATG combined with CsA is an effective and feasible treatment for AA, while patients should be appropriately selected.