Nationwide survey on the use of horse antithymocyte globulins (ATGAM) in patients with acquired aplastic anemia: A report on behalf of the French Reference Center for Aplastic Anemia

[Acquired severe aplastic anemia in emerging countries: Management from allogeneic hematopoietic cell transplantation indication until post-transplant follow-up SFGM-TC]

Management of acquired aplastic anemia (AA) in emerging countries depends on the means of prognostic stratification, treatment and logistics available. During the 13th annual harmonization workshop of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to elaborate unified guidelines for allogeneic hematopoietic cell transplantation (Allo-HCT) in this disease. In terms of practice, the conclusions are as follows; The use of anti-tymocyte globuline (ATG) is mainly from rabbit and very little from horse. Access to bone marrow graft, total body irradiation, and the international unrelated donor registries is limited, which justifies the use of peripheral blood stem cells, chemotherapy-based conditioning, and related alternative donor. The workshop recommends matched sibling allo-HCT in all patients aged less than 40 years with acquired severe or very severe AA. For patients aged over than 40 years, or who lack an HLA-identical donor, treatment with the combination of cyclosporin, horse ATG, eltrombopag or cyclosporine, eltrombopag is recommended. If horse ATG and eltrombopag are not available, matched sibling allo-HCT may be indicated as first-line therapy in patients aged between 40-60 years, and good performance status. Although, in patients who have failed immunosuppressive treatments and thrombopoietin agonists, and in the absence of HLA-matched donor, a haplo-identical allo-HCT with modified Baltimore conditioning is recommended.

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

Comparison of haploidentical-allogeneic hematopoietic stem cell transplantation and intensive immunosuppressive therapy for patients with severe aplastic anemia with an absolute neutrophil count of zero: a retrospective study

A retrospective analysis was conducted based on the clinical data from 60 patients older than 16 years from January 2016 to January 2021. All the patients were newly diagnosed with severe aplastic anemia (SAA) with an absolute neutrophil count (ANC) of zero. We compared the hematological response and survival of haploidentical-allogeneic hematopoietic stem cell transplantation (HID-HSCT) (n = 25) and intensive immunosuppressive therapy (IST) (n = 35) treatments. At six months, the overall response rate and complete response were significantly higher in the HID-HSCT group than those in the IST group (84.0% vs. 40.0%, P = 0.001; 80.0% vs. 17.1%, P = 0.001). With a median follow-up of 18.5 months (4.3~30.8 months), patients in the HID-HSCT group had longer overall survival and event-free survival (80.0% vs. 47.9%, P = 0.0419; 79.2% vs. 33.5%, P = 0.0048). These data suggested that HID-HSCT might be an effective alternative treatment option for adult patients with SAA with an ANC of zero, which requires further validation in an additional prospective study.

Aplastic Anemia as a Roadmap for Bone Marrow Failure: An Overview and a Clinical Workflow

In recent years, it has become increasingly apparent that bone marrow (BM) failures and myeloid malignancy predisposition syndromes are characterized by a wide phenotypic spectrum and that these diseases must be considered in the differential diagnosis of children and adults with unexplained hematopoiesis defects. Clinically, hypocellular BM failure still represents a challenge in pathobiology-guided treatment. There are three fundamental topics that emerged from our review of the existing data. An exogenous stressor, an immune defect, and a constitutional genetic defect fuel a vicious cycle of hematopoietic stem cells, immune niches, and stroma compartments. A wide phenotypic spectrum exists for inherited and acquired BM failures and predispositions to myeloid malignancies. In order to effectively manage patients, it is crucial to establish the right diagnosis. New theragnostic windows can be revealed by exploring BM failure pathomechanisms.

Clinical Outcome of Acquired Post-Immunosuppressive-Therapy Aplastic Anemia in Pediatric Patients: A 13-Year Experience in Two Southern China Tertiary Care Centers

Objective

The aim of the present study is to evaluate the efficacy, complications, and contributing factors of immunosuppressive therapy (IST) response in children with acquired aplastic anemia (AA) and to explore optimal therapeutic methods for different clinical AA types.

Methods

A total of 130 children diagnosed with acquired AA underwent IST in the Department of Pediatrics at Sun Yat-sen Memorial Hospital and the Department of Pediatrics at Seventh Affiliated Hospital, Sun Yat-sen University, between January 1, 2006, and July 15, 2020. The overall survival (OS), response rates, complications, and response predictors were analyzed. The response rates were compared according to clinical AA type.

Results

All 130 children with AA were followed up with for a median of 50.6 months. Among the patients, 25 had non-severe AA (NSAA), 64 had severe AA (SAA), and 41 had very severe AA (VSAA). All patients initially received IST. In 13 patients, the IST failed; these patients received an allo-hematopoietic stem cell transplant as a salvage regimen. The OS rate was 90.3% ± 2.8%, and the response rates at 3, 6, 9, and 12 months were 34.19%, 39.32%, 49.57%, and 66.67%, respectively. The prolonged follow-up period might have led to higher response rates, especially in patients with SAA and VSAA. A multivariate logistic regression analysis of prognostic factors was conducted; the results showed that high red blood cell (RBC) and platelet (PLT) counts were associated with a high overall response rate and that the RBC count at diagnosis is a major contributing factor.

Conclusion

With the use of rabbit anti-thymocyte globulin, proper cyclosporine management, and a prolonged IST follow-up period, a higher number of patients with acquired AA than normal achieved response. Proportionally, the number of patients who achieved remission within 12 months was higher in the SAA group (38.18%→63.64%) and VSAA group (28.95%→65.79%) than in the NSAA group (58.33%→75%). Higher RBC and PLT counts at diagnosis can predict a favorable outcome.

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.

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.

Allogeneic hematopoietic stem cell transplantation in aplastic anemia: current indications and transplant strategies

Treatment options for newly diagnosed aplastic anemia (AA) patient includes upfront allogeneic hematopoietic stem cell transplant (HSCT) or immunosuppressive therapy (IST). With recent advances in supportive care, conditioning regimens and post-transplant immunosuppression the overall survival for HSCT approaches 70-90%. Transplant eligibility needs to be assessed considering age, comorbidities, donor availability and probability of response to immunosuppressive therapy (IST). Upfront HSCT should be offered to children and young adults with matched related donor (MRD). Upfront HSCT may also be offered to children and young adults with rapidly available matched unrelated donor (MUD) who require urgent HSCT. Bone marrow (BM) graft source and cyclosporine (CsA) plus methotrexate (MTX) as graft versus host disease (GVHD) prophylaxis are preferable when using anti-thymocyte globulin (ATG) based conditioning regimens. Alemtuzumab is an acceptable alternative to ATG and is used with CsA alone and with either BM or peripheral blood stem cells (PBSC). Cyclophosphamide (CY) plus ATG conditioning is preferable for patients receiving MRD transplant, while Fludarabine (Flu) based conditioning is reserved for older adults, those with risk factors of graft failure and those receiving MUD HSCT. For haploidentical transplant, use of low dose radiotherapy and post-transplant cyclophosphamide has resulted in a marked reduction in graft failure and GVHD.

A study assessing the feasibility of randomization of pediatric and young adult patients between matched unrelated donor bone marrow transplantation and immune-suppressive therapy for newly diagnosed severe aplastic anemia: A joint pilot trial of the North American Pediatric Aplastic Anemia Consortium and the Pediatric Transplantation and Cellular Therapy Consortium

BACKGROUND

Recent data show survival after matched unrelated donor (MUD) bone marrow transplantation (BMT) is similar to matched sibling procedures for young patients with severe aplastic anemia (SAA). Donor delays, risk of transplant-related mortality (TRM), and concern about chronic graft versus host disease raise questions about whether MUD BMT or immune suppression therapy (IST) should be preferred initial therapy for young patients lacking matched sibling donors.

PROCEDURE

We performed a pilot trial to assess the feasibility of randomizing patients under age 26 with newly diagnosed SAA to receive IST versus MUD BMT. Primary aims assessed the acceptability of randomization and timing of BMT. Secondary aims measured toxicities, response, and survival.

RESULTS

Sixty-seven patients with possible SAA were screened at nine centers. Of 57 with confirmed SAA, 23 underwent randomization and received therapy with a median follow-up of 18 months. Of 12 randomized to BMT, 10 started BMT as initial therapy at a median of 36 days after randomization. One BMT recipient experienced secondary graft failure, requiring a second procedure. Six of 11 randomized to IST responded, whereas five with refractory disease underwent successful salvage BMT. One patient achieving complete response relapsed after discontinuation of immune suppression and died of infection after salvage BMT.

CONCLUSIONS

This feasibility study showed that a high percentage of patients underwent randomization and received up-front MUD BMT. Our study lays the groundwork for a larger randomized trial that will define best initial therapy for young patients with SAA who have an available MUD.

[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).

Multivariate logistic analysis of predictors of response to immunosuppressive therapy in children with aplastic anemia: a double-center study

BACKGROUND

Immunosuppressive therapy (IST) composed of antithymocyte globulin (ATG) and cyclosporine A (CSA) is one of the standard therapies in pediatric patients with acquired aplastic anemia (AA), but predictors of IST are lack of consensus.

PROCEDURES

Ninety-four patients from two pediatric medical centers in China were included between January 2005 and March 2018. Clinical factors associated with the efficacy were analyzed according to multivariate logistic regression model previously established.

RESULTS

We discovered that overall responsiveness was 77.66%. Five out of 35 factors were statistically significant in univariate analysis. Based on the cutoff point chosen by receiver operating characteristic (ROC) curve, 5 continuous variables were made categorical, among which 3 variables with significance were employed to establish the logistic regression equation. Based on these 3 variables, we found that starting IST within 126 days of the first appearance of symptoms (X1, p = .003), absolute neutrophil count (ANC) higher than 0.435×10⁹/L (X2, p = .012), and rate of decreased actual lymphocyte count (ALC) higher than 59.2% within the 1st week after IST (X3, p = .001) were three independent risk factors for response to IST. The rate of decreased ALC higher than 59.2% after IST was the most significant variable (OR = 9.355, Log (P) = -2.161 + 2.149X1 + 1.662X2 + 2.236X3). The accuracy, sensitivity, and specificity of the model were 86.2%, 94.5% and 57.1%, respectively.

CONCLUSION

Duration of AA, ANC and decreased ALC rate after IST might predict the response to IST, among which the rate of decreased ALC after IST is the most important predictive factor.

Burden of illness among patients with severe aplastic anemia who have had insufficient response to immunosuppressive therapy: a multicenter retrospective chart review study

This study assessed treatment patterns and healthcare resource utilization (HRU) of patients with severe aplastic anemia (SAA) with insufficient response to immunosuppressive therapy (IST). A retrospective chart review was conducted at Dana-Farber Cancer Institute (DFCI), United States, and Hôpital Saint-Louis (HSL), France. Eligible patients were ≥ 18 years old, diagnosed with acquired SAA between January 1, 2006, and July 31, 2016, had insufficient response to IST, and had ≥ 12 months of follow-up post-diagnosis. Overall survival (OS) was estimated using the Kaplan-Meier method. Among the 40 patients, mean age at diagnosis was 44 years and 53% were women. Median follow-up time after SAA diagnosis was 48.3 months. Ninety-five percent of patients received antithymocyte globulin (ATG) as primary therapy prior to hematopoietic stem cell transplant (HSCT). Most common secondary SAA therapies prior to HSCT were eltrombopag (28%) and androgens (15%). Seventy-five percent of patients received HSCT. Prior to HSCT, patients received an average of 2.7 red blood cell (RBC) and 3.3 platelet transfusions per month; patients had 0.9 hospitalizations, 0.4 emergency room visits, and 12.8 office visits per year. Five-year OS was 75%, with infection as the primary cause of death. Additionally, this study provides information on the subgroup of patients receiving eltrombopag which was the most common secondary therapy. This study quantified transfusion and HRU burden associated with SAA and demonstrated high 5-year survival in a recently treated cohort.

Immunosuppressive therapy (IST) in adult patients with acquired aplastic anemia (AA): A single-center experience over the past 15 years

OBJECTIVE

Immunosuppressive therapy (IST) with horse anti-thymocyte globulin (hATG) and cyclosporine (CsA) is considered one of the first-line therapies in patients (pts) with acquired aplastic anemia (AA).

METHODS

In our single-center, retrospective analysis response rates (RRs) to ATG/CsA at a minimum of 6 mo were evaluated in 67 treatment-naïve (TN) AA pts (52.2% (35/67) females; median age 45 y (range 18-89 y)) being treated at the West German Cancer Center at the Department of Hematology at the University Hospital of Essen between April 2000 and December 2015.

RESULTS

Overall 6 mo RRs in TN pts following ATG/CsA were 67.2% (45/67) (5-year OS: 79.5%). In TN hATG-treated pts 6 mo RRs were 75.5% (37/49) (5-year OS: 81%) compared to 44.4% (8/18) (5-year OS 73.5%) following rabbit ATG (rATG). Response to ATG/CsA was dependent of age, absolute reticulocyte count (ARC), and disease severity. Six mo RRs to salvage ATG/CsA in relapsed/refractory (R/R) pts were 37.5% (6/16).

CONCLUSION

Our data independently confirm the findings of previous studies that hATG/CsA is superior to rATG/CsA in TN pts. The lack of hATG availability should not result in abstaining it from an indicated ATG therapy, even though ATGAM^® is not registered in Germany.