Management of the refractory aplastic anemia patient: what are the options?

Long-term effects of hematopoietic growth factors in aplastic anemia patients treated with immunosuppression: Meta-analysis of randomized controlled trials

BACKGROUND AND PURPOSE

Immunosuppressive therapy is the frontline treatment for aplastic anemia patients ineligible for transplantation. The long-term effects of hematopoietic growth factors (HGF) added to standard immunosuppressive therapy are still unclear. We performed a systematic review and meta-analysis to clarify this issue.

METHODS

A comprehensive search of databases was conducted including 5 international electronic databases (Cochrane, PubMed, Embase, Web of Science, and LILACS) and 4 Chinese electronic databases (Chinese Bio-medicine Database, Chinese National Knowledge Infrastructure, WanFang Data, and China Science and Technology Journal Database databases) from database inception until February, 2022. We included randomized controlled trials that assigned patients with acquired aplastic anemia treated with immunosuppressive therapy (IST), which compared between the addition of HGF and placebo or no treatment. The co-primary outcome were the overall survival (OS) and late clonal malignant evolution at the end of follow-up.

RESULTS

Nine randomized controlled trials including 719 participants were identified. The addition of growth factors to immunosuppression yielded no difference in OS (relative risks [RR], 1.08, 95% confidence interval [CI] 0.99-1.18). HGF was not associated with higher occurrence of secondary myelodysplastic syndromes/acute myeloid leukemia (RR, 1.09, 95% CI 0.43-2.78) or paroxysmal nocturnal hemoglobulinemia (RR, 1.38, 95% CI 0.68-2.81) at the end of follow-up. No difference were found in overall response (RR, 1.16, 95% CI 0.98-1.37), infections occurrence (RR, 0.82; 95% CI, 0.51-1.31) or relapse (RR, 0.65; 95% CI, 0.37-1.13).

CONCLUSIONS

HGF as an adjunct to IST has no impact on long-term OS, late clonal malignant evolution, response rate, relapse or infections occurrence. HGF could be added to standard IST for high-risk patients with delayed neutrophil recovery without concern for long-term consequences but could not be recommended as routine clinical practice.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42021275188.

[Reassessing the six months prognosis of patients with severe or very severe aplastic anemia without hematological responses at three months after immunosuppressive therapy]

Objective: To reassess the predictors for response at 6 months in patients with severe or very severe aplastic anemia (SAA/VSAA) who failed to respond to immunosuppressive therapy (IST) at 3 months. Methods: We retrospectively analyzed the clinical data of 173 patients with SAA/VSAA from 2017 to 2018 who received IST and were classified as nonresponders at 3 months. Univariate and multivariate logistic regression analysis were used to evaluate factors that could predict the response at 6 months. Results: Univariate analysis showed that the 3-month hemoglobin (HGB) level (P=0.017) , platelet (PLT) level (P=0.005) , absolute reticulocyte count (ARC) (P<0.001) , trough cyclosporine concentration (CsA-C0) (P=0.042) , soluble transferrin receptor (sTfR) level (P=0.003) , improved value of reticulocyte count (ARC(△)) (P<0.001) , and improved value of soluble transferrin receptor (sTfR(△)) level (P<0.001) were related to the 6-month response. The results of the multivariate analysis showed that the PLT level (P=0.020) and ARC(△) (P<0.001) were independent prognostic factors for response at 6 months. If the ARC(△) was less than 6.9×10(9)/L, the 6-month hematological response rate was low, regardless of the patient's PLT count. Survival analysis showed that both the 3-year overall survival (OS) [ (80.1±3.9) % vs (97.6±2.6) %, P=0.002] and 3-year event-free survival (EFS) [ (31.4±4.5) % vs (86.5±5.3) %, P<0.001] of the nonresponders at 6 months were significantly lower than those of the response group. Conclusion: Residual hematopoietic indicators at 3 months after IST are prognostic parameters. The improved value of the reticulocyte count could reflect whether the bone marrow hematopoiesis is recovering and the degree of recovery. A second treatment could be performed sooner for patients with a very low ARC(△).

[Retreatment with immunosuppression for 23 patients with refractory or relapsed severe aplastic anemia]

Objective: This study aims to evaluate the efficacy and safety of secondary immunosuppressive therapy (IST) in refractory or relapsed severe aplastic anemia. Methods: The hematologic response and safety of 23 patients with refractory or relapsed SAA treated with secondary IST (including ATG/ALG + cyclosporine or HD-CTX) in our hospital were retrospectively analyzed. Results: A total of 23 patients were involved, including 11 males and 12 females, with a median age of 21 (11-62) years. In the refractory group, the interval of IST was 7 (6-12) months. In the relapsed group, on the other hand, the interval between two courses of IST was 39 (14-51) months. At 6 months after IST, the overall response rate was 69.5% (16/23) ; 60% (6/10) of the refractory group vs 77% (10/13) of the relapsed group; 64% (7/11) of the ATG/ALG group vs 75% (9/12) of the HD-CTX group. Among the patients who got the hematologic response, two patients relapsed again, all of them from the relapse group. After the third IST, they got the response again. Conclusion: The second IST is safe and effective for refractory and relapsed SAA patients; the early serologic reaction should be paid attention to when using the same ATG/ALG, and the risk can be reduced by changing the type of ATG/ALG or other IST programs. The third IST can still obtain the treatment response for the second relapse patients.

Risk factors associated with poor response to immunosuppressive therapy in acquired aplastic anemia: A meta-analysis of retrospective studies

Acquired aplastic anemia (AA) is a rare hematological disease characterized by bone marrow hypocellularity and varying degrees of pancytopenia. Immunosuppressive therapy (IST) is currently one of the first-line treatments for AA; however, unresponsiveness remains a major concern. Although previous studies have suggested several common risk factors for unresponsiveness, there are currently no widely accepted predictors. Therefore, a meta-analysis of clinical trials including information on factors associated with unresponsiveness of AA to IST was performed in the present study. The PubMed, Embase and Cochrane Library databases were searched for clinical studies on AA evaluating the association between risk factors and unresponsiveness to IST. After the factors were defined from the selected studies, the association between these factors and unresponsiveness to IST was analyzed using Review Manager software. A total of 10 studies comprising 1,820 cases were included in the present meta-analysis. The following factors were identified as predictors of unresponsiveness: Age (≥60 years), sex, absolute neutrophil count, severity of the disease, paroxysmal nocturnal hemoglobinuria clone, human leukocyte antigen (HLA)-DR2 and cytogenetic abnormalities (CAs). Among these factors, only age (≥60 years) [odds ratio (OR)=1.65], HLA-DR2 negativity (OR=2.72) and CAs (OR=1.93) exhibited a statistically significant association with unresponsiveness to IST (P=0.006, P=0.04 and P=0.01, respectively). In conclusion, the present meta-analysis revealed that age ≥60 years, HLA-DR2 negativity and CAs are risk factors for unresponsiveness to IST. This result may enable clinicians to select an effective therapeutic scheme for patients with AA and even provide novel clues to the pathogenesis of AA.

Management of aplastic anemia after failure of frontline immunosuppression

Introduction: About 60% of aplastic anemia (AA) patients are in need of further treatment after frontline standard immunosuppressive therapy (IST). This along with the prolonged survival of AA subjects who do not respond to or relapse after this treatment makes management of these patients a rising and very challenging issue. Areas covered: Literature research, carried out from the most commonly used databases, included the following keywords: aplastic anemia, immunosuppressive treatment, antithymocyte globuline, ciclosporine A, refractory aplastic anemia, relapsing aplastic anemia, hematopoietic stem cell transplantation including haploidentical and cord blood transplantations thrombopoietin mimetics, supportive treatment, chelation and infections. Studies on the treatment of aplastic anemia with different levels of evidence were included. Top level of evidence studies (metanalyses and randomized prospective controlled trials) were a minority because severe AA, particularly in the subset of patients who fail upfront IST, is an extremely rare disease. Guidelines from National Societies and review articles were also included. Expert opinion: The most commonly used treatments after failure of upfront immunosuppression are hematopoietic stem cell transplantation, a second course of immunosuppression and thrombopoietin mimetics alone or in combination with immunosuppression. Other potential options are alemtuzumab, androgens, oral cyclosporine A in monotherapy. Not many comparative studies exist to clearly establish the superiority of one over another strategy. Therefore, the choice of the best treatment for these patients should rely on major driving factors like patient's age and comorbidities, availability of a matched unrelated donor, donor's characteristics and drug-availability.

Evaluation of eltrombopag in patients with aplastic anemia in real-world experience

Background

Although eltrombopag has recently been approved for treating AA, the effects of its clinical use remain unknown.

Methods

We retrospectively analyzed 11 patients with AA, who had been treated with eltrombopag from August 2017 to May 2018.

Results

Overall response rate was 55%. There was tri-lineage recovery in four patients and platelet recovery in two. The reactive time was within 8 weeks after treatment initiation. Stage at the initial assessment, the neutrophil-to-lymphocyte ratio and platelet counts were significantly different between the responders and non-responders.

Conclusion

Eltrombopag is a promising agent for treating patients with any degree of AA.

Aplastic anemia: Etiology, molecular pathogenesis, and emerging concepts

Aplastic anemia (AA) is rare disorder of bone marrow failure which if severe and not appropriately treated is highly fatal. AA is characterized by morphologic marrow features, namely hypocellularity, and resultant peripheral cytopenias. The molecular pathogenesis of AA is not fully understood, and a uniform process may not be the culprit across all cases. An antigen-driven and likely autoimmune dysregulated T-cell homeostasis is implicated in the hematopoietic stem cell injury which ultimately founds the pathologic features of the disease. Defective telomerase function and repair may also play a role in some cases as evidenced by recurring mutations in related telomerase complex genes such as TERT and TERC. In addition, recurring mutations in BCOR/BCORL, PIGA, DNMT3A, and ASXL1 as well as cytogenetic abnormalities, namely monosomy 7, trisomy 8, and uniparental disomy of the 6p arm seem to be intimately related to AA pathogenesis. The increased incidence of late clonal disease has also provided clues to accurately describe plausible predispositions to the development of AA. The emergence of newer genomic sequencing and other techniques is incrementally improving the understanding of the pathogenic mechanisms of AA, the detection of the disease, and ultimately offers the potential to improve patient outcomes. In this comprehensive review, we discuss the current understanding of the immunobiology, molecular pathogenesis, and future directions of such for AA.

Eltrombopag: a review of its use in patients with severe aplastic anaemia

Eltrombopag (Promacta®) is an orally active thrombopoietin receptor agonist recently approved in the US for the treatment of patients with severe aplastic anaemia who have had an insufficient response to immunosuppressive therapy. This article reviews the efficacy and tolerability of eltrombopag in this indication and overviews its pharmacological properties. Eltrombopag does not compete with thrombopoietin and binds to a different site on the receptor, producing additive effects. It stimulates haematopoietic stem cells and promotes haematopoietic recovery in patients with aplastic bone marrow. Eltrombopag increased platelet counts and can also increase red blood cell and neutrophil counts. In patients with severe aplastic anaemia refractory to prior immunosuppressive therapy, oral eltrombopag at dosages ≤150 mg once daily for 12-16 weeks produced a haematological response in at least one cell lineage in 40 % of patients. Trilineage responses were achieved in nearly one-half of the responders during extended treatment. In robust responders, stable haematological counts were maintained after eltrombopag discontinuation. Eltrombopag was generally well tolerated, with increased liver transaminases as the only dose-limiting toxicity. Clonal cytogenetic abnormalities were observed in 19 % of patients and dysplasia in 5 % of patients.

Current concepts in the pathophysiology and treatment of aplastic anemia

Historically viewed in isolation as an odd, rare, and invariably fatal blood disease, aplastic anemia is now of substantial interest for its immune pathophysiology, its relationship to constitutional BM failure syndromes and leukemia, and the success of both stem cell transplantation and immunosuppressive therapies in dramatically improving survival of patients. Once relegated to a few presentations in the red cell and anemia sessions of the ASH, the Society now sponsors multiple simultaneous sessions and plenary and scientific committee presentations on these topics. This update emphasizes developments in our understanding of immune mechanisms and hematopoietic stem cell biology and new clinical approaches to stem cell stimulation as a therapy, alone and in combination with conventional suppression of the aberrant immune system.

Allogeneic BM transplantation for the treatment of aplastic anemia: current results and expanding donor possibilities

Allogeneic BM transplantation from an HLA-identical sibling donor leads to long-term survival in the majority of patients (>80%). Therefore, survival is no longer the sole concern and attention has to be paid to decreasing the incidence and severity of long-term complications. For patients without a sibling donor, transplantation from a well-matched unrelated donor can be considered after failure of a previous course of immunosuppressive therapy. After transplantation from an HLA-identical sibling donor or from an unrelated one, the use of peripheral blood stem cells must be strongly discouraged because they have been systematically associated with an increased incidence of chronic GVHD compared with the use of BM as a stem cell source, leading to an unacceptably higher risk of treatment-related mortality in this setting. For as yet unknown reasons, the age limit after which transplantation results are less satisfactory remains 40 years of age.