Diagnosis and treatment of acquired aplastic anemia

Upfront Umbilical Cord Blood Transplantation Versus Immunosuppressive Therapy for Pediatric Patients With Idiopathic Severe Aplastic Anemia

Umbilical cord blood transplantation (UCBT) has been rarely reported as a first-line treatment for idiopathic severe aplastic anemia (SAA) patients lacking HLA-matched sibling donors (MSD). Our study aimed to compare the clinical outcomes of pediatric SAA patients who received UCBT and immunosuppressive therapy (IST) upfront. A retrospective analysis was performed on 43 consecutive patients who received frontline IST (n = 17) or UCBT (n = 26) between July 2017 and April 2022. The 3-year overall survival (OS) was comparable between the UCBT and IST groups (96.2% versus 100%, P = .419), while the 3-year event-free survival (EFS) was significantly better in the former than in the latter (88.5% versus 58.8%, P = .048). In the UCBT group, 24 patients achieved successful engraftment, 2 patients developed severe acute graft-versus-host disease (aGVHD), no extensive chronic GVHD (cGVHD), and a high GVHD-free, failure-free survival (GFFS) of 84.6% at 3 years. After 1 year of treatment, 12 patients in the IST group responded, while 5 patients did not achieve remission and 2 patients had disease relapse. At both 3 and 6 months after treatment, the proportion of transfusion-independent patients was higher in the UCBT group than in the IST group. Faster immune recovery and earlier transfusion independence further reduced the risk of infection and bleeding, thereby improving health-related quality of life in the UCBT-treated group. Our results suggested that UCBT as upfront therapy may be an effective and safe option for pediatric SAA patients, with favorable outcomes in experienced centers.

Regulation of erythropoiesis: emerging concepts and therapeutic implications

The process of erythropoiesis is complex and involves the transfer of cells from the yolk sac to the fetal hepar and, ultimately, to the bone marrow during embryonic development. Within the bone marrow, erythroid progenitor cells undergo several stages to generate reticulocytes that enter the bloodstream. Erythropoiesis is regulated by various factors, with erythropoietin (EPO) synthesized by the kidney being the promoting factor and hepcidin synthesized by the hepar inhibiting iron mobilization. Transcription factors, such as GATA and KLF, also play a crucial role in erythropoiesis. Disruption of any of these factors can lead to abnormal erythropoiesis, resulting in red cell excess, red cell deficiency, or abnormal morphological function. This review provides a general description of erythropoiesis, as well as its regulation, highlighting the significance of understanding the process for the diagnosis and treatment of various hematological disorders.

Comparable Outcomes Between Unrelated and Haploidentical Stem Cell Transplantation in Adult Patients With Severe Aplastic Anemia

BACKGROUND

Regarding patients with severe aplastic anemia (SAA) who fail immunosuppressive therapy and lack an HLA-matched sibling donor (MSD), the best alternative donor including unrelated (URD) and haploidentical (HAPLO) donors for allogeneic stem cell transplantation (SCT) remains to be established.

METHODS

We analyzed the comprehensive outcomes of 153 consecutive adult SAA patients treated with SCT from alternative donors: 73 HLA-well matched (8/8) URDs (WM-URDs), 34 mismatched (6-7/8) URDs (MM-URDs), and 46 HAPLOs.

RESULTS

Neutrophil/platelet engraftments were achieved at a median of 11/15 days for WM-URDs, 13/16.5 days for MM-URDs, and 12/14 days for HAPLOs, respectively. The 3-year overall survival (OS), failure-free survival, cumulative incidence of graft-failure, and transplant-related mortality were statistically not different among the 3 groups: 90.3%, 87.5%, 2.7%, and 9.8% for WM-URDs; 85.3%, 81.7%, 0%, and 14.7% for MM-URDs, and 84.4%, 82.3%, 6.5%, and 11.2% for HAPLOs, respectively. The rates of other complications, including graft-versus-host disease, cytomegalovirus DNAemia, hemorrhagic cystitis, invasive fungal disease, secondary malignancies, and sinusoidal obstruction syndrome, were also statistically not different. Subgroup analysis of the MM-URD group showed that the 3-year OS of patients receiving SCTs from 6/8-URDs were worse than those receiving SCTs from 7/8-URDs (75.0% versus 94.4%, P = 0.26).

CONCLUSIONS

There was no significant difference in the SCT outcomes with WM-URDs, MM-URDs, or HAPLO donors. The clinician can make the best choice among these alternative donor sources based on the host/donor features and the urgency of the need for SCT. However, the selection of 6/8-URDs should be avoided due to inferior survival outcomes.

Mixed chimerism after allogeneic hematopoietic stem cell transplantation for severe aplastic anemia

A retrospective study on 287 patients with SAA who underwent allo-HSCT between October 2012 and January 2020 was conducted to explore the outcomes, risk factors and treatment options for MC. Among 287 AA patients who excluded Fanconi anemia (FA), Congenital dyskeratosis (DKC), Paroxysmal nocturnal hemoglobinuria (PNH), etc.112 underwent matched sibling donor (MSD)-HSCT, 91 matched unrelated donor-HSCT and 84 haploidentical-HSCT. Patients were divided into the following 4 groups: group 1: Donor chimerism (DC); group 2: MC without cytopenia; group 3: MC with cytopenia; group 4: secondary graft failure (SGF).

Compared with the other three groups, SGF predicted a poor prognosis of SAA (P< 0.001). In addition, SGF was associated with the early (within 3 months after transplantation) presence of MC and the high levels of MC. Uni- and multivariate logistic regression analysis showed that donor/recipient sex-mismatching and CTX + ATG regimen were high-risk factors for MC. Of note, in MC patients with cytopenia (group 3), the effective response rate reached 55% (6/11) following enhanced immunosuppression combined with cellular therapy, while only one of the four was effective who received enhanced immunosuppression alone.

SGF was associated with poor prognosis, early presence of MC and increased levels of recipient chimerism. The donor/recipient sex-mismatching and CTX + ATG regimen based MSD-HSCT were risk factors for MC. Cellular therapy could improve the effective response rate of patients with progressive MC.

Outcomes of allogeneic haematopoietic stem cell transplantation for patients with severe aplastic anaemia using the porcine antilymphocyte globulin-containing conditioning regimen

Antithymocyte globulin (ATG) is widely used for allogeneic haematopoietic stem cell transplantation (allo-HSCT) in severe aplastic anaemia (SAA). Only rabbit-ATG (r-ATG) and porcine-antilymphocyte globulin (p-ALG) are available in China, but the p-ALG-containing conditioning regimen for allo-HSCT in SAA has seldom been reported. In this study, we retrospectively evaluated the outcomes of 41 SAA patients receiving allo-HSCT with a p-ALG-containing conditioning regimen in our transplantation centre. All patients engrafted, and no death during conditioning was observed. The actuarial 3-year overall survival (OS) rates were 95.1 ± 3.4%. The actuarial 3-year disease-free survival (DFS) rates were 85.0 ± 5.7%. Acute graft-versus-host disease (aGVHD) predicted inferior OS (p < 0.05). The interval from diagnosis to transplantation for more than 100 days predicted an inferior DFS rate (p < 0.05) and a higher graft rejection/poor graft function (GR/PGF) rate (p < 0.01). In conclusion, the p-ALG-containing regimen showed satisfactory effects and safety in allo-HSCT for SAA patients. P-ALG could be a potential alternative preparation for r-ATG in SAA allo-HSCT.

Evaluating and monitoring bone marrow hypoplasia in adults with aplastic anemia via high-resolution iliac magnetic resonance imaging in the current era

The diagnosis and monitoring of aplastic anemia (AA) rely heavily on a complete blood count (CBC), and multiple-site bone marrow (BM) aspirations and biopsies. However, these approaches have certain limitations. We aimed to assess high-resolution magnetic resonance imaging (MRI) as a complementary approach for evaluating BM hypoplasia and monitoring treatment response in adults with AA in the current era.Twelve newly diagnosed AA patients and 12 sex- and age-matched healthy controls were enrolled in this study from January 2017 to August 2018. A bilateral iliac 3.0T MRI was used to collect data for each subject, and the signal intensity on the T1-weighted images (T1WIs) were expressed as a contrast-to-noise ratio (CNR). The MRI, CBC, and BM biopsy data were analyzed and compared.A qualitative analysis identified a significant difference in MRI signal characteristics between the AA group and the healthy control group. The clinical classifications of very severe aplastic anemia (VSAA) and severe aplastic anemia (SAA) corresponded to pattern I and pattern II on the MR images, respectively. However, this imaging classification did not correlate with the biopsy-based BM cellularity measure. A quantitative analysis showed a significantly higher signal intensity in AA patients than in controls. A within-group comparison revealed that more severe types of AA, based on the clinical classification, corresponded to stronger signals. Notably, MRI could detect treatment response earlier than CBC, regardless of whether there were improvements in hematopoiesis.MRI can be used to predict the therapeutic effects in patients with AA and is an important complementary tool for evaluating and monitoring BM hypoplasia.

Reactivation and dynamics of cytomegalovirus and Epstein-Barr virus after rabbit antithymocyte globulin and cyclosporine for aplastic anemia

OBJECTIVES

This study aimed to identify the natural course of cytomegalovirus (CMV)/Epstein-Barr virus (EBV) after rabbit antithymocyte globulin and cyclosporine (rATG-CsA) for aplastic anemia (AA).

METHODS

In 113 prospectively observed AA patients treated with rATG-CsA, the CMV/EBV cohort was classified into two groups by baseline viremic status: no viremia (CMV-G1, n = 112; EBV-G1, n = 98) and the presence of viremia (CMV-G2, n = 1; EBV-G2, n = 13).

RESULTS

In CMV-G1, the mean CMV load increased up to 3 months but was completely resolved from 6 months. The mean EBV load of EBV-G1 showed a peak at 1 month and then gradually decreased over time but remained detectable throughout the observation period. EBV-G2 showed fluctuating EBV dynamics. With reactivation rates of 38.4% in CMV-G1 and 62.2% in EBV-G1, a longer time to rATG-CsA from diagnosis and a lower absolute lymphocyte count at 1 month from rATG-CsA were significantly associated with CMV and EBV reactivation, respectively. The mean peak CMV and EBV loads of patients with CMV-related (3.5%) and EBV-related (0.9%) diseases were evidently higher than those of the remaining patients without CMV and EBV diseases in the respective cohort.

CONCLUSION

Considering frequent reactivation and distinct courses of CMV/EBV, virologic surveillance is recommended after rATG-CsA for AA.

Alternative Donor Transplantation with High-Dose Post-Transplantation Cyclophosphamide for Refractory Severe Aplastic Anemia

Severe aplastic anemia (SAA) is a life-threatening hematopoietic stem cell disorder that is treated with bone marrow transplantation (BMT) or immunosuppressive therapy (IST). The management of patients with refractory SAA after IST is a major challenge. Alternative donor BMT is the best chance for cure in refractory SAA, but morbidity and mortality from graft failure and complications of graft-versus-host disease (GVHD) have limited enthusiasm for this approach. Here, we employed post-transplantation high-dose cyclophosphamide in an effort to safely expand the donor pool in 16 consecutive patients with refractory SAA who did not have a matched sibling donor. Between July 2011 and August 2016, 16 patients underwent allogeneic (allo) BMT for refractory SAA from 13 haploidentical donors and 3 unrelated donors. The nonmyeloablative conditioning regimen consisted of antithymocyte globulin, fludarabine, low-dose cyclophosphamide, and total body irradiation. Post-transplantation cyclophosphamide 50 mg/kg/day i.v. on days +3 and +4 was administered for GVHD prophylaxis. Additionally, patients received mycophenolate mofetil on days +5 through 35 and tacrolimus from day +5 through 1 year. The median age of the patients at the time of transplantation was 30 (range, 11 to 69) years. The median time to neutrophil recovery over 1000 × 103/mm3 for 3 consecutive days was 19 (range, 16 to 27) days, to red cell engraftment was 25 (range, 2 to 58) days, and to last platelet transfusion to keep platelets counts over 50 × 103/mm3 was 27.5 (range, 22 to 108) days. Graft failure, primary or secondary, was not seen in any of the patients. All 16 patients are alive, transfusion independent, and without evidence of clonality. The median follow-up is 21 (range, 3 to 64) months. Two patients had grade 1 or 2 skin-only acute GVHD. These same 2 also had mild chronic GVHD of the skin/mouth requiring systemic steroids. One of these GVHD patients was able to come off all IST by 15 months and the other by 17 months. All other patients stopped IST at 1 year. Nonmyeloablative alloBMT using post-transplantation cyclophosphamide allowed for safe expansion of the donor pool to include HLA-haploidentical donors. This approach appears promising in refractory SAA patients. Importantly, engraftment was 100%, pre-existing clonal disease was eradicated, and the risk of GVHD was low.

Second allogeneic stem cell transplant for aplastic anaemia: a retrospective study by the Severe Aplastic Anaemia Working Party of the European Society for Blood and Marrow Transplantation

We analysed the outcome of a second allogeneic haematopoietic stem cell transplant (alloHSCT) in 162 patients reported to the European Society for Blood and Marrow Transplantation between 1998 and 2009. Donor origin was a sibling in 110 and an unrelated donor in 52 transplants, respectively. The stem cell source was bone marrow in 31% and peripheral blood in 69% of transplants. The same donor as for the first alloHSCT was used in 81% of transplants whereas a change in the choice of stem cell source was reported in 56% of patients, mainly from bone marrow to peripheral blood. Neutrophil and platelet engraftment occurred in 85% and 72% of patients, after a median time of 15 and 17 days, respectively. Grade II-IV acute graft-versus-host disease (GVHD) and chronic GVHD occurred in 21% and 37% of patients, respectively. Graft failure (GF) occurred in 42 patients (26%). After a median follow-up of 3·5 years, the 5-year overall survival (OS) was 60·7%. In multivariate analysis, the only factor significantly associated with a better outcome was a Karnofsky/Lansky score ≥80 (higher OS). We conclude that a second alloHSCT is feasible rescue option for GF in SAA, with a successful outcome in 60% of cases.

The combined use of cytokine-induced killer cells and cyclosporine a for the treatment of aplastic anemia in a mouse model

In this study, we investigated the combined use of cytokine-induced killer (CIK) cells and cyclosporine A (CsA) to treat a mouse model of aplastic anemia (AA). CIK cells were cultured and injected alone or in combination with CsA into mice that had previously been induced into AA by busulfan and mouse interferon-γ (IFN-γ). The CIK cell-treated group had a survival rate of 55%, which was similar to the 60% survival rate observed in the CsA-treated group. The combination group showed a survival rate as high as 90%, while none of the mice in the no-treatment group survived to the end of the experiment. The CIK cells produced multiple cytokines, including several hematopoietic growth factors, which could promote the expansion of mouse bone marrow mononuclear cells in vitro. CsA reduced the proportion of CD4(+) T cells and the level of IFN-γ. The combined CIK cell and CsA treatment exhibited the best curative effect, a finding that might be due to the influence of these factors on both hematopoiesis and immunity. These data suggest that the combination of CIK cells and immunosuppressive therapy might be a candidate therapy for AA in the future.

Porcine antilymphocyte globulin (p-ALG) plus cyclosporine A (CsA) treatment in acquired severe aplastic anemia: a retrospective multicenter analysis

Severe aplastic anemia (SAA) is a life-threatening bone marrow failure syndrome characterized by pancytopenia and hypocellular bone marrow. Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with SAA ineligible for allogeneic stem cell transplantation. This study aimed to evaluate the efficacy and safety profile of porcine antilymphocyte globulin (p-ALG) plus CsA in the treatment of acquired SAA. Clinical information of 69 SAA patients treated with p-ALG plus CsA was collected and retrospectively analyzed for early mortality, response rate, survival rate, side effects, and other complications. The median age at diagnosis was 27 years (range 14 to 52). The overall response rate was 76.8 % with a 90-day median response time (range 30 ~ 360 days). Overall response rates at 3, 6, 12, 18, and 24 months were 63.8, 73.9, 76.8, 75.4, and 75.4 %, respectively. The median follow-up time for surviving patients was 24 months (range 4 ~ 44 months) and the 2-year overall survival (OS) rate was 88.4 %. The disease-free survival (DFS) rate at 2 years was 85.5 %. Older age (≥45 years), very (v)SAA subgroup, and lower baseline absolute lymphocyte count (<1 × 10(9)/L) were independent unfavorable predictors of overall survival (p < 0.05). Less than one third of patients had serum sickness or allergic reaction during ALG therapy, but symptoms could easily be relieved by steroid treatment; 27.54 % had mild hepatic impairment. Taken together, p-ALG showed similar efficacy and safety profiles to rabbit or horse ATG in IST of acquired SAA. It can be a suitable alternative preparation for rabbit ATG with the great advantage of lower medical expenses.

Early intensified intravenous cyclosporine therapy predicts favorable response to immunosuppressive therapy with rabbit antithymocyte globulin in patients with severe aplastic anemia

Because of relapse after horse ATG (hATG) therapy, rabbit ATG (rATG) would be a realistic alternative as second line immunosuppressive therapy (IST) in severe aplastic anemia (SAA) patients. We investigated whether intensified intravenous (IV) CsA therapy with rATG would increase the response of IST in SAA patients. Sixty-one of the 123 patients received IV CsA therapy with rATG during initial 2 weeks then changed to oral form (IV CsA group), while other 62 patients just received oral CsA therapy with rATG (oral CsA group). Hematologic response rates at 3 and 6 months were not different between IV CsA group and oral CsA group (p=0.795, p=0.079). However, CsA levels during initial 15 days were higher in response-achieved group than response-not-achieved group. Intensive IV CsA group maintained CsA level ≥ 300 ng/ml during 15 days had higher responses at 6 months than non-intensive IV CsA group and oral CsA group (p=0.009, p=0.021). Intensive IV CsA group (HR=3.239, 95% CI=1.095-8.997, p=0.013) independently predicted favorable the hematologic response at 6 months of IST. Early intensified CsA therapy was important to achieve favorable outcomes in IST including rATG.

The efficacy of rabbit antithymocyte globulin with cyclosporine in comparison to horse antithymocyte globulin as a first-line treatment in adult patients with severe aplastic anemia: a single-center retrospective study

Antithymocyte globulin (ATG) is the drug of choice for immunosuppressive therapy (IST) in patients with severe aplastic anemia (SAA) ineligible for allogeneic stem cell transplantation. Recently, rabbit ATG with cyclosporine A has been used as a first-line IST regimen in patients with SAA because of unavailability of horse ATG. We retrospectively analyzed adult SAA patients who were treated with horse ATG (n=46) or rabbit ATG (n=53) between Feb 2001 and May 2010 to compare hematologic response and survival. Overall response rates at 3, 6, 12, and 18 months were similar in both the horse and rabbit ATG groups: 28.3 versus 35.8 % (P=0.421), 39.1 versus 45.3 % (P=0.537), 45.7 versus 49.1 % (P=0.735), and 47.8 versus 50.9 % (P=0.757), respectively. The complete response (CR) rate at 6 months in the horse ATG was significantly superior in comparison with the rabbit ATG (13.0 versus 1.9 %, P=0.031). But CR rates became similar in both groups after 6 months: 17.4 versus 11.3 % (P=0.387) at 12 months and 21.7 versus 22.6 % (P=0.914) at 18 months. Lymphocyte depletion after ATG was more profound and protracted in the rabbit ATG group compared to the horse ATG group. Overall survival (P=0.460) and failure-free survival (P=0.911) were not significantly different between the two groups. Our retrospective study demonstrated that the efficacy of first-line IST with rabbit ATG is similar to that with horse ATG. However, the time from treatment to CR was longer with rabbit ATG than with horse ATG, partly due to more profound and protracted lymphocyte depletion.

Management of acquired aplastic anemia in children

The diagnosis of aplastic anemia in children requires exclusion of a variety of inherited or acquired BM failure syndromes with similar phenotypes. An efficient diagnostic plan is important because time from diagnosis to 'final' treatment is directly related to outcome regardless of the therapeutic option chosen. The gold standard of therapy remains hematopoietic SCT with a graft of BM cells for those children with matched sibling donors. Conversely for children without a sibling donor the high response and markedly improved overall survival rates of combined immunosuppressive therapy have proven robust, especially when horse derived anti-thymocyte globuline plus ciclosporine A are used. Incomplete response, relapse and progression to myelodysplasia/leukemia however have emerged as significant long-term issues. Improvements in outcome of alternative donor transplantation and the use of established and novel immunosuppressive agents provide multiple alternatives for treating refractory or relapsed patients. Regardless of the type of therapeutic approach, patients require centralized treatment in a center of excellence, ongoing monitoring for recurrence of disease and/or therapy-related immediate side effects and long-term effects.

Should we still use Camitta's criteria for severe aplastic anemia?

Background

The criteria by Camitta for diagnosis in severe aplastic anemia (SAA) has been used since 1976. However, there has been no attempt to verify the Camitta's criteria, that the survival in patients with SAA may differ by absolute neutrophil count (ANC), platelet count (PLT), and corrected reticulocyte count (CRC), which are components of the Camitta's criteria.

Methods

117 SAA patients diagnosed by the Camitta's criteria were analyzed, retrospectively. Univariate and multivariate analyses were used to evaluate the factors affecting overall survival (OS).

Results

Response by immunosuppressive therapy (IST) or stem cell transplantation (SCT) significantly affected OS (P=0.001). Therefore, we excluded treatment responders for analysis. Finally, 92 SAA patients including treatment non-responders by IST or SCT and conservative care group were analyzed by using univariate and multivariate analyses. The median age of analyzed patients was 54.5 years. Male to female ratio was 1:1. The median follow-up duration was 74.23 months (range, 54.71-93.74 months). The median ANC, PLT, and CRC were 394/µL, 12,000/µL, and 0.39%, respectively. In multivariate analyses, ANC <500/µL or ≥500/µL (P=0.015, HR 2.694, 95% CI: 1.20-6.01) and age (P=0.015, HR 1.022, 95% CI: 1.00-1.04) were the significant factors for OS.

Conclusion

ANC could be an essential, not an optional criterion for diagnosing SAA. This study suggests the possibility that the Camitta's criteria be modified. Studies in large cohorts are needed to transform the Camitta's criteria.

Age-associated alteration of γδ T-cell repertoire and different profiles of activation-induced death of Vδ1 and Vδ2 T cells

It has been suggested that γδ T cells are involved in certain autoimmune disorders. To establish reference data for clinical studies to explore the role of γδ T cells in autoimmune bone marrow failure syndrome, we examined the γδ T-cell repertoire in 120 healthy Japanese individuals by flow cytometry. The average numbers of T lymphocytes in blood were as follows: 1,084 ± 369 (SD) αβ T cells, 68 ± 44 γδ T cells, 16 ± 12 Vδ1 T cells, and 43 ± 36 Vδ2 T cells (/μl). Absolute numbers of γδ T cells decreased with aging (R = -0.378, P < 0.001). The decrease of γδ T cells was the result of reduction of Vδ2, but not of Vδ1, T cells. Numbers of Vδ2 T cells were significantly higher in male than in female donors (P = 0.007). The Vδ2 T cells but not Vδ1 T cells showed a rapid reduction in cell numbers on mitogen stimulation, which was accompanied by modest down-regulation of Bcl-2 protein expression. These results indicate that age and gender have a major impact on γδ T-cell repertoire in Japanese donors, as well as European and American donors. The age-related decrease of Vδ2 T cells may be explained by their susceptibility to activation-induced cell death.

Diagnosis and management of aplastic anemia

Aplastic anemia remains a diagnosis of exclusion. Our ability to reliably diagnose, and therefore exclude, a variety of inherited or acquired diseases with similar phenotypes has improved markedly. An efficient diagnostic plan is important because time from diagnosis to treatment is related to outcome regardless of the therapeutic option chosen. HSCT remains the mainstay of therapy for those with matched sibling donors, and results have improved even further in recent years. For those without a sibling donor, the high response and overall survival rates of combined immunosuppressive therapy (IST) have proven robust. Nonetheless, incomplete response, relapse, and progression to myelodysplasia/leukemia have more clearly emerged as significant long-term issues. Improvements in outcome of alternative donor transplantation and the use of established and novel immunosuppressive agents provide multiple alternatives for treating refractory or relapsed patients. Best practices in this regard are not yet clearly established and may vary by a variety of demographic and treatment-specific factors. Regardless of the type of therapeutic approach, patients require ongoing monitoring for occurrence of disease and/or therapy-related side effects.