Predictors of response to immunosuppressive therapy with antithymocyte globulin and cyclosporine and prognostic factors for survival in patients with severe aplastic anemia

Modified Delphi panel consensus recommendations for management of severe aplastic anemia

ABSTRACT

Severe aplastic anemia (SAA) is a rare hematologic condition for which there is no clear management algorithm. A panel of 11 experts on adult and pediatric aplastic anemia was assembled and, using the RAND/University of California, Los Angeles modified Delphi panel method, evaluated >600 varying patient care scenarios to develop clinical recommendations for the initial and subsequent management of patients of all ages with SAA. Here, we present the panel's recommendations to rule out inherited bone marrow failure syndromes, on supportive care before and during first-line therapy, and on first-line (initial management) and second-line (subsequent management) therapy of acquired SAA, focusing on when transplant vs medical therapy is most appropriate. These recommendations represent the consensus of 11 experts informed by published literature and experience. They are intended only as general guidance for experienced clinicians who treat patients with SAA and are in no way intended to supersede individual physician and patient decision making. Current and future research should validate this consensus using clinical data. Once validated, we hope these expert panel recommendations will improve outcomes for patients with SAA.

Significance of absolute neutrophil count before allogeneic hematopoietic stem cell transplantation in adult patients with aplastic anemia

The impact of absolute neutrophil count (ANC) before allogenic hematopoietic stem cell transplantation (HSCT) on the outcomes for patients with aplastic anemia (AA) remains unclear. We retrospectively evaluated the relationship between ANC before transplantation and patient outcomes, involving 883 adult Japanese patients with AA who underwent allogeneic HSCT as their first transplantation between 2008 and 2020. Patients were divided into three groups based on ANC: 0/µL (n = 116); 1-199 (n = 210); and ≥ 200 (n = 557). In the low ANC groups (ANC < 200), patient age was higher, previous anti-thymocyte globulin (ATG) treatments were infrequent, duration from diagnosis to transplantation was shorter, hematopoietic cell transplantation-comorbidity index (HCT-CI) was higher, ATG-based conditioning was used infrequently, and peripheral blood stem cell from related donor and cord blood were used frequently. In multivariate analysis, patient age, previous ATG treatment, HCT-CI, stem cell source, and ANC before transplantation were significantly associated with 5-year overall survival (OS) ("ANC ≥ 200": 80.3% vs. "ANC 1-199": 71.7% vs. "ANC 0": 64.4%). The cumulative incidence of bacterial infection, invasive fungal disease, and early death before engraftment were significantly higher in the low ANC groups. Among patients with ANC of zero before transplantation, younger patient age, shorter duration from diagnosis to transplantation, HCT-CI of 0, and bone marrow from related donor as stem cell source were significantly associated with better OS. Consequently, ANC before allogeneic HSCT was found to be a significant prognostic factor in adult patients with AA. Physicians should pay attention to ANC before transplantation.

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.

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.

Natural killer cells in peripheral blood at diagnosis predict response to immunosuppressive therapy in severe aplastic anemia

Immunosuppressive therapy (IST) consisting of antihuman thymocyte globulin and cyclosporine A is the first-line therapy for patients with severe aplastic anemia (AA) who are ineligible for undergoing bone marrow transplantation. The aim of the study was to evaluate the correlation between natural killer (NK) cells and response to IST in SAA patients. We retrospectively included 93 AA patients and detected NK cells in peripheral blood by flow cytometry. Both the proportion and absolute number of NK cells in newly diagnosed SAA patients were significantly lower than in controls, while the proportion and absolute number of NK cells in complete remission patients treated with IST were remarkably increased compared with treatment-naïve SAA patients. Additionally, the absolute number of NK cells at diagnosis was positively correlated with initial blood counts. For SAA patients receiving IST, the proportion of NK cells at baseline and 6 months was significantly higher in responders than in non-responders. Unexpectedly, we found that the increase in the proportion of NK cells at 6 months after IST was closely related to the recovery of hematopoiesis. ROC curve identified 7.3% of NK cells proportion at diagnosis as the cutoff value to predict response to IST. The response rate was higher in NK proportion high group than in NK proportion low group. Multivariate logistic regression analysis further confirmed the independent predictive value of NK cells proportion in assessing IST response. The proportion of NK cells at diagnosis may serve as a promising predictor of response to IST in patients with SAA.

An investigation of long-term outcome of rabbit anti-thymocyte globulin and cyclosporine therapy for pediatric severe aplastic anemia

Children with severe aplastic anemia (SAA) face heterogeneous prognoses after immunosuppressive therapy (IST). There are few models that can predict the long-term outcomes of IST for these patients. The objective of this paper is to develop a more effective prediction model for SAA prognosis based on clinical electronic medical records from 203 children with newly diagnosed SAA. In the early stage, a novel model for long-term outcomes of SAA patients with IST was developed using machine-learning techniques. Among the indicators related to long-term efficacy, white blood cell count, lymphocyte count, absolute reticulocyte count, lymphocyte ratio in bone-marrow smears, C-reactive protein, and the level of IL-6, IL-8 and vitamin B12 in the early stage are strongly correlated with long-term efficacy (P < .05). Taken together, we analyzed the long-term outcomes of rabbit anti-thymocyte globulin and cyclosporine therapy for children with SAA through machine-learning techniques, which may shorten the observation period of therapeutic effects and reduce treatment costs and time.

Antihuman T lymphocyte porcine immunoglobulin combined with cyclosporine as first-line immunosuppressive therapy for severe aplastic anemia in China: a large single-center, 10-year retrospective study

Background

Antihuman T lymphocyte porcine immunoglobulin (p-ATG) has been the most common ATG preparation in immunosuppressive therapy (IST) in Chinese patients with severe aplastic anemia (SAA) since 2009.

Objectives

This study aimed to evaluate the early hematologic response and long-term outcomes of a large cohort of patients with SAA who received p-ATG plus cyclosporine (CsA) as first-line therapy from 2010 to 2019.

Design

This is a single-center retrospective study of medical records.

Methods

We analyzed the data of 1023 consecutive patients with acquired aplastic anemia (AA) who underwent p-ATG combined with CsA as a first-line IST treatment from 2010 to 2019 at our department.

Results

The median age of the patients was 24 (4-75) years, and the median follow-up time was 57.2 months (3 days-137.5 months). There was an early mortality rate of 2.8% with a median death time of 0.9 months (3 days-2.9 months). The overall response rates were 40.6% and 56.1% at 3 and 6 months, respectively. The 5-year cumulative incidences of relapse and clonal evolution were 9.0% [95% confidence interval (CI) = 4.2-16.0%] and 4.5% (95% CI = 1.4-10.6%), respectively. The 5-year overall survival (OS) and event-free survival rates were 83.7% (95% CI = 81.1-86.0%) and 50.4% (95% CI = 47.1-53.5%), respectively.

Conclusion

p-ATG combined with CsA for the treatment of AA is effective and safe, and p-ATG can be used as an alternative ATG preparation for the standard IST regimen in areas in which h-ATG is not available.

Development and validation of early death risk score model for emergency status prediction in very severe aplastic anemia

This study developed and validated the Early Death Risk Score Model for early identification of emergency patients with very severe aplastic anemia (VSAA). All 377 patients with VSAA receiving first-line immunosuppressive therapy (IST) were categorized into training (n=252) and validation (n=125) cohorts. In the training cohort, age >24 years, absolute neutrophil count ≤0.015×10⁹/L, serum ferritin >900ng/mL and times of fever before IST >1 time were significantly associated with early death. Covariates were assigned scores and categorized as: low (score 0-4), medium (score 5-7) and high (score ≥8) risk. Early death rate was significantly different between risk groups and the validation cohort results were consistent with those of the training cohort. The area under the receiver operating characteristic curve for the model was 0.835 (0.734,0.936) in the training cohort and 0.862 (0.730,0.994) in the validation cohort. The calibration plots showed high agreement, and decision curve analysis showed good benefit in clinical applications. The VSAA Early Death Risk Score Model can help with early identification of emergency VSAA and optimize treatment strategies. Emergency VSAA with high risk is associated with high early death rate, and alternative donor hematopoietic stem cell transplantation could be a better treatment than IST even without HLA-matching.

The prognostic impact of previously infectious complications on allogeneic hematopoietic stem cell transplantation for patients with severe aplastic anemia: A single-center, retrospective study

Whether infections before transplantation impair the survival of patients with severe aplastic anemia (SAA) remains unclear. The aim of this retrospective cohort analysis was to compare survival between patients with SAA who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) with infection (n=66) and patients without infection (n=189) from one medical center. There were no differences in baseline characteristics, except that more patients in the infection group were diagnosed with VSAA (59.09% vs. 30.69%, P<0.001), and their grafts were more peripheral blood stem cells (89.39% vs. 76.72%, P=0.042). In addition, the percentage of patients with multidrug-resistant organism colonization or infection in the infection group was larger (16.7% vs. 0.5%, P<0.001). The median days of engraftment were similar between the two groups; however, the 28-day engraftment rates of neutrophils and platelets were lower in the infection group. No differences were observed in terms of grades II–IV acute graft-versus-host disease (aGVHD) (P=0.418), grades III–IV aGVHD (P=0.075), mild to severe chronic GVHD (cGVHD) (P=0.899), and moderate to severe cGVHD (P=0.342). Patients in the infection group had more bloodstream infections before engraftment (28.8% vs. 15.3%, P=0.016), and the primary cause of death was infection instead of aGVHD in contrast to patients without infection (16.7% vs. 4.2%, P=0.002). Finally, the estimated overall survival (OS), failure-free survival (FFS), and GVHD-free FFS at 5 years were 63% (95% CI, 51–78), 60% (95% CI, 47–74), and 55% (95% CI, 43–70) in patients with infection before transplantation versus 86% (95% CI, 81–92) (P<0.001), 82% (95% CI, 76–88) (P<0.001), and 75% (95% CI, 69–82) (P=0.003) in patients without infection before transplantation, respectively. Multivariate analysis identified haploidentical HSCT and pre-HSCT anti-infection response, defined as partial remission (PR) or stable disease (SD), as adverse factors of OS and FFS. In conclusion, our study demonstrated that SAA patients with infection defined as PR or SD but not complete remission before allo-HSCT showed inferior survival compared with patients without infection. Therefore, more attention should be paid to prophylaxis and complete control of infectious complications before transplantation among SAA patients.

[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(△).

Haploidentical haematopoietic stem cell transplantation for the treatment of severe aplastic anaemia patients with high-risk factors who lack an HLA-matched sibling donor

This study aimed to analyse the efficacy of haploidentical donor (HID) haematopoietic stem cell transplantation as a first-line treatment for severe aplastic anaemia (SAA) with high-risk factors (infection or very severe aplastic anaemia,VSAA) in patients who lack an HLA-matched sibling donor (MSD). The patients with infection were treated with anti-infection therapy, and allogeneic haematopoietic stem cell transplantation (HSCT) was carried out after the infection being effectively controlled was in accordance with the stable infection (SI) standard. A total of 44 SAA patients receiving MSD transplantation (n=19) and HID transplantation (n=25) were included in this study. There was no significant difference in neutrophil engraftment between the two groups [MSD vs. HID, 19 (11-38) vs. 22 (15-47).P=0.241], and the difference in platelet engraftment was statistically significant [MSD vs. HID, 11(7-33) vs. 20 (12-69), P=0.034]. The HID group exhibited a higher incidence of grade II-IV acute graft-versus-host disease (aGVHD) (HID vs. MSD, 48.0% vs10.5%, P=0.034)and a higher incidence of chronic GVHD (cGVHD) than the MSD group (64.0% vs. 21.1%, P=0.026). There was no significant difference between overall survival (OS) following HID and MSD transplantation (84.0% vs. 89.5%, P=0.664) and failure-free survival (FFS)(80.0% vs. 84.2%, P=0.965). The interval from diagnosis to transplantation (>50d) and ECOG (>2) were independent factors associated with OS and FFS. HID HSCT may be an effective and safe option for SAA patients with high-risk factors who lack an MSD.

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.

Rapid blood cell recovery with immunosuppressive therapy combined with romiplostim in a patient with very severe hepatitis-associated aplastic anemia who underwent liver transplantation

Patients with hepatitis-associated aplastic anemia (HAA) who undergo living-donor liver transplantation (LDLT) have a poor prognosis with infections and bleeding complications. Rapid recovery of blood cells is critical for preventing these complications and improving the outcome. Immunosuppressive therapy (IST) combined with thrombopoietin receptor agonists is considered effective for aplastic anemia. However, there are no data on the benefits of adding thrombopoietin receptor agonists to IST for HAA. We present the case of a child with severe HAA who underwent LDLT, and who achieved rapid blood cell recovery with IST combined with romiplostim, a thrombopoietin receptor agonist. In addition, despite having undergone LDLT, the patient had no adverse events such as serious liver dysfunction or thrombosis. This case suggests that IST combined with thrombopoietin receptor agonists may be a promising treatment option for HAA patients undergoing LDLT.

Relationship between plasma rabbit anti-thymocyte globulin concentration and immunosuppressive therapy response in patients with severe aplastic anemia

OBJECTIVES

Patients with acquired aplastic anemia (AA) without HLA-matched sibling donors or aged >40 years receive immunosuppressive therapy (IST) with anti-thymocyte globulin (ATG). We investigated the relationship between plasma rabbit ATG (r-ATG) concentration and IST response.

METHODS

From May 2012 to October 2017, 81 patients with severe AA who required initial IST were included. A 1:1 block randomization was employed for 2.5 and 3.5 mg/kg doses of r-ATG.

RESULTS

No significant difference in response rates was observed between the 2.5 and 3.5 mg/kg groups (63% vs. 58%, P = .894). Median r-ATG concentrations on days 14 and 28 after IST were 15.2 (0.0-97.7) and 1.8 (0.0-74.9 µg/mL), respectively. According to r-ATG concentration, response rates were significantly higher in the group with higher r-ATG concentration than in those with lower r-ATG concentration (day 14, 88% vs. 52%; P = .006 and day 28, 79% vs. 46%; P = .005). In multivariate analysis, higher r-ATG concentrations at day 28 were independent predictors of favorable response to IST at 6 months (odds ratio, 0.29; 95% confidence interval, 0.09-0.93; P = .037).

CONCLUSIONS

The present data indicate that higher r-ATG concentration at day 28 resulted in improved IST response.

Predicting response of severe aplastic anemia to immunosuppression combined with eltrombopag

Pretreatment blood counts, particularly an absolute reticulocyte count ≥25×10⁹/L, correlate with response to immunosuppressive therapy in severe aplastic anemia. In recent trials, eltrombopag combined with standard immunosuppressive therapy yielded superior responses than those to immunosuppressive therapy alone. Our single institution retrospective study aimed to elucidate whether historical predictors of response to immunosuppressive therapy alone were also associated with response to immunosuppressive therapy plus eltrombopag. We sought correlations of blood counts, thrombopoietin levels and the presence of paroxysmal nocturnal hemoglobinuria clones with both overall and complete responses in 416 patients with severe aplastic anemia, aged 2-82 years (median, 30 years), initially treated with immunosuppressive therapy plus eltrombopag between 2012 and 2019 (n=176) or with immunosuppressive therapy alone between 1999 and 2010 (n=240). Compared to non-responders, patients in the group of overall responders to immunosuppressive therapy plus eltrombopag had significantly higher pretreatment absolute reticulocyte counts, higher neutrophil counts and reduced thrombopoietin levels, as also observed for the group treated with immunosuppressive therapy alone. Addition of eltrombopag markedly improved the overall response in subjects with an absolute reticulocyte count between 10-30×10⁹/L from 60% (54 of 90) to 91% (62 of 68). Absolute lymphocyte count correlated with complete response in the groups treated with immunosuppressive therapy with or without eltrombopag, especially in adolescents aged ≥10 years and adults, but the correlation was reversed in younger children. Platelet count and the presence of a paroxysmal nocturnal hemoglobinuria clone did not correlate with responses to immunosuppressive therapy. Blood counts remain the best predictors of response to nontransplant therapies in severe aplastic anemia. Addition of eltrombopag to immunosuppressive therapy shifted patients with a lower absolute reticulocyte count into a better prognostic category.

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.

Eltrombopag, oral immunosuppressant and androgen combination therapy in twelve patients with refractory severe aplastic anemia

Objective: Eltrombopag monotherapy or eltrombopag combined with immunosuppressant has achieved robust hematologic responses in severe aplastic anemia (SAA). In patients with refractory SAA, for whom hematopoietic stem cell transplantation is unavailable, we attempted to combine eltrombopag with oral immunosuppressant and androgen, to further improve hematologic response. Methods: We collected and analyzed data retrospectively from twelve refractory SAA cases who had received combination therapy of eltrombopag, oral immunosuppressant and androgen. All these patients had received intensive immunosuppressive treatment (IST) for more than 6 months and were evaluated as nonresponders. Results: A total of 12 SAA patients were treated with a combination of eltrombopag, an oral immunosuppressant (cyclosporine, N = 9; tacrolimus, N = 3) and androgen. The median maximum dose of eltrombopag was 75 mg/day (range, 75-150). After a median follow-up of 8.5 months (7-23), the overall response rate (ORR) was 42% (5/12, including trilineage, N = 4; hemoglobin + platelet, N = 1). Two of 5 responders reached normal blood counts. Optimal hematological response rates were reached at 6 months. The median increase in neutrophil, hemoglobin and platelet count were 1.64 × 10⁹ /L (0.71-2.66), 53 g/L (25-66.5) and 25 × 10⁹ /L (14-230), respectively. In general, the combination therapy was well tolerated; however, two patients suffered from non-lethal upper extremity venous thrombosis when they were platelet transfusion-dependent. Conclusion: Eltrombopag, oral immunosuppressant and androgen combination therapy in patients with IST-refractory SAA is feasible and could restore multi-lineage hematopoiesis. Thrombosis risk of eltrombopag still needs to be monitored.

Long-term outcomes of 172 children with severe aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine

This study retrospectively analyzed the clinical outcome of 172 children with newly diagnosed severe aplastic anemia (SAA) between January 2008 and April 2018, who received rabbit antithymocyte globulin (ATG) and cyclosporine (CsA) as first-line treatment. The median age at diagnosis was 5 years (range, 1-14). The overall response rates were 22.7%, 45.3%, and 61% at 40 days, 3 months, and 6 months, respectively, after rabbit ATG. In multivariate analysis, mild disease severity was the only predictor of favorable response at 6 months (P = 0.006). In the present study, median follow-up period was 63 months (range, 1-135). The 5-year overall survival (OS) and failure-free survival (FFS) rates were 90.5% and 70.4%. Multivariate analysis showed that erythroid burst-forming units (BFU-E) > 2/10⁵ bone marrow mononuclear cell (BMMNC) (P = 0.037) and time interval before IST ≤ 30 days (P = 0.017) were independent positive predictors for OS, meanwhile BFU-E > 2/10⁵BMMNC (P = 0.029) was the only favorable prognostic factor for FFS.

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.

Predicting response to porcine antilymphocyte globulin plus cyclosporine A in children with acquired severe aplastic anemia

BACKGROUND

In severe aplastic anemia (SAA), predictive markers of response to immunosuppressive therapy (IST) of porcine antilymphocyte globulin (pALG) have not been well defined. We investigated whether clinical and laboratory findings before treatment could predict response in a pediatric cohort.

METHODS

In this study, we included 70 newly diagnosed SAA children and treated them with pALG. The response rate was documented during follow-up. The log-rank test compared response rates between the potential predictive factors.

RESULTS

The response rate was 57.1% at 24 months follow-up. In log-rank test, mild disease severity was the most significant predictive marker of better response (P < 0.001); SAA patients with higher absolute reticulocyte count (ARC) and platelet level showed a higher response rate (both P < 0.001). Although insignificantly, elderly children and male sex show better response rate after treatment. The response rate worsened when the time interval before IST was more than 60 days.

CONCLUSION

Modified IST with pALG was suitable for SAA children, and favorable response correlates with mild disease severity was identified. ARC and platelet status also appeared to be a reproducible prognostic model for response rate. IST should be started as soon as possible, given that the response rate worsens as the interval between diagnosis and treatment increases.

Updated Guidelines for the Treatment of Acquired Aplastic Anemia in Children

PURPOSE OF REVIEW

This review aimed to provide updated guidelines for the management of children with acquired aplastic anemia (AA), particularly focusing on hematopoietic stem cell transplantation (HSCT).

RECENT FINDINGS

Failure-free survival for children with aplastic anemia has been shown to be better after bone marrow transplantation (BMT) from matched or one-locus mismatched related donors (MRD/1MMRD) than after immunosuppressive therapy (IST). A combination of the absence of minor paroxysmal nocturnal hemoglobinuria clones and short telomere length was identified as a strong predictor of a poor response to IST. Upfront HSCT from matched unrelated donors (MUD) and MRD was recently demonstrated to have comparable outcomes. Moreover, unrelated cord blood transplantation (UCBT) and haploidentical HSCT have shown promising outcomes, and the fludarabine/melphalan-based regimen has resulted in excellent survival without poor graft function. BMT from MRD/1MMRD is the treatment of choice. When a MRD/1MMRD is not available, upfront BMT from a MUD should be considered for patients with only a slim chance of responding to IST. UCBT and haploidentical HSCT are promising options. This updated treatment algorithm should improve overall outcomes for children with AA.

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

Antithymocyte globulins (ATG) plus cyclosporine (CSA) is the gold standard immunosuppressive treatment (IST) for patients with aplastic anemia. A prospective randomized trial showed in 2011 that hATG was superior to rabbit ATG for first-line treatment of severe AA. The French Health Agency (ANSM) permitted a patient-named authorization for temporary use (ATU) program of hATG (ATGAM, Pfizer) in patients with AA in 2011 since commercial access to hATG is not approved. We took advantage of this program to analyze the outcomes of 465 patients who received antithymocyte globulins (ATGAM) plus CSA as first line treatment (n = 379; 81.5%), or for refractory (n = 26) or relapsed disease (n = 33), from September 2011 to March 2017. In the entire cohort one year, 72% of the patients had partial and 13% had complete response, with worse response for patients with severe AA and a longer interval between diagnosis and IST (more than 6 months). Severe adverse events were mainly linked to infections (24%), hemorrhages (6%), and elevated liver function tests (5%). Overall at 12 months, 9.7% of patients required second line IST and 15.6% received transplantation. Fifty-five patients died during the study mainly because of infections (53%). Factors predicting independently worse survival were age over 40 years, neutrophils less than 0.5 × 10⁹ /L, male gender and longer delay between diagnosis and hATG (>6 months period). This study does illustrate the results of ATGAM with CSA in a true-life perspective and confirms ATGAM as standard of care IST to treat patients with AA not eligible for HSCT.

Post-therapeutic recovery of serum interleukin-35 level might predict positive response to immunosuppressive therapy in pediatric aplastic anemia

BACKGROUND

The predictive value of interleukin-35 (IL-35) on efficacy of immunosuppressive therapy (IST) in aplastic anemia (AA) has not been well investigated. The aim of the study was to evaluate the association between serum IL-35 level and response to IST in pediatric AA.

METHODS

A total of 154 children with AA and 154 controls were included between January 2012 and December 2013. Blood and bone marrow fluid specimens were collected. Serum level of IL-35 was determined by enzyme-linked immunosorbent assay. Patients were treated with IST, and response to therapy was evaluated during 180-day follow-up period after starting therapy.

RESULTS

Serum levels of IL-35 at admission decreased significantly in patients compared with that in controls (10.9 ± 5.5 pg ml^-1 and 45.3 ± 8.8 pg ml^-1, p < 0.001). After starting IST, serum levels of IL-35 in patients recovered 30.7 ± 9.7 pg ml^-1 in the first 28 days (p < 0.001). During the follow-up period, increased range of serum IL-35 level ≥30.7 pg ml^-1 in the first 28 days was associated with effective response to therapy (odds ratio 7.97, 95% confidence interval 3.82-16.79). In addition, Fas/FasL protein expression in bone marrow mononuclear cells dropped significantly in the same group of patients in the first 28 days (p < 0.05).

CONCLUSION

The study revealed that post-therapeutic recovery of circulating IL-35 concentration might be an independent predictor for effective response to IST in pediatric AA. Moreover, apoptosis might be involved in such a forecasting process.

How I treat acquired aplastic anemia

Acquired severe aplastic anemia (SAA) is a rare hematologic disease associated with significant morbidity and mortality. Immune destruction of hemopoietic stem cells plays an important role in pathogenesis, as shown by successful treatment with immunosuppressive agents, leading to transfusion independence or complete recovery of peripheral blood counts in a proportion of patients. Growth factors can be combined with immunosuppressive therapy (IST) and may improve response rates, as recently shown with thrombopoietin analogs. Anabolic steroids may still play a role in combination with IST. The problem with IST is failure to respond and the development of late clonal disorders. Bone marrow transplantation (BMT) is the other therapeutic option: a matched sibling donor remains the best choice. For patients lacking a matched family donor, unrelated donors can be readily found, although mostly for patients of Caucasian origin. Other BMT options include unrelated cord blood or mismatched family donors. Acute and chronic graft-versus-host disease remain important complications of BMT. Patient age is a strong predictor of outcome for both IST and BMT, and must be considered when designing therapeutic strategies. Early diagnosis and treatment, as well as long-term monitoring, remain crucial steps for successful treatment of SAA.

Efficacy of rabbit antithymocyte globulin as first-line treatment of severe aplastic anemia: an Asian multicenter retrospective study

Due to the unavailability of horse antithymocyte globulin (ATG) in many markets worldwide, patients with severe aplastic anemia (SAA) are limited to the use of rabbit ATG. We aimed to analyze hematologic response and overall survival (OS) of Asian patients treated with rabbit ATG as first-line therapy of SAA. We retrospectively reviewed the medical records of 97 consecutive patients who received rabbit ATG as first-line treatment of SAA from 2006 to 2012 at centers in four Asian countries. The primary endpoint was 6- and 12-month overall response rates (ORR) for patients receiving rabbit ATG within the recommended dose range (2.5-3.75 mg/kg/day). Secondary endpoints included ORR in patients receiving any dose of rabbit ATG and 2-year OS. For patients who received rabbit ATG within the recommended dose range, 6- and 12-month ORRs were 17.4 and 63.6 %, respectively. For patients who received any dose of rabbit ATG, 6- and 12-month ORRs were 24.3 and 68.6 %, respectively. The 2-year OS rate was 86.3 %. Rabbit ATG is effective for treatment of SAA in Asian patients. The 12-month ORR and 2-year OS with rabbit ATG were comparable to historical results obtained with horse ATG.

Biomarkers for predicting clinical response to immunosuppressive therapy in aplastic anemia

The decision to select hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST) as initial therapy in acquired aplastic anemia (AA) is currently based on patient age and the availability of a human leukocyte antigen (HLA)-matched donor. Although IST is a promising treatment option, the ability to predict its long-term outcomes remains poor due to refractoriness, relapses, and the risk of clonal evolution. Several predictive biomarkers for response to IST have been posited, including age, gender, pre-treatment blood cell counts, cytokines, gene mutations, paroxysmal nocturnal hemoglobinuria (PNH), and telomere length (TL). While previous studies have provided substantial biological insights into the utility of IST, the prognostic power of the reported biomarkers is currently insufficient to contribute to clinical decision making. Recently, a large retrospective analysis proposed the combination of minor PNH clones and TL as an efficient predictor of IST response. Identification of a reliable predictor would provide a useful tool for determining the most appropriate treatment choice for AA patients, including up-front HSCT from HLA-matched unrelated donor. The present review summarizes studies evaluating the utility of biomarkers in predicting the clinical response to IST of patients with AA, and provides a baseline for prospective studies aimed at validating previously reported biomarkers.

Markedly High Plasma Thrombopoietin (TPO) Level is a Predictor of Poor Response to Immunosuppressive Therapy in Children With Acquired Severe Aplastic Anemia

BACKGROUND

Immunosuppressive therapy (IST) is commonly used for patients with acquired severe aplastic anemia (SAA). Because the clinical response rate and therapeutic outcome for individual patients to IST varies, an in vitro test that identifies potential responders would be desirable.

METHODS

We evaluated the relationship between thrombopoietin (TPO) levels at the time of diagnosis and the response to IST at 6 months in 85 children (median age, 9.0 years; range, 1.0-15.5 years) with acquired SAA using enzyme-linked immunosorbent assay. Thirty-one age-matched healthy individuals were used as controls. All patients received antithymocyte globulin and cyclosporine.

RESULTS

Overall, 39 patients (45.9%) responded to IST at 6 months. TPO plasma levels were significantly higher in nonresponders than in responders (1,555.8 vs. 1,284.7 pg/ml, respectively; P = 0.031). Multivariate analysis identified the TPO levels of >1,796.7 pg/ml (TPO-high group, 20 patients; odds ratio (OR), 8.285; 95% confidence interval (CI), 2.114-32.904; P = 0.002) as independent poor predictors of IST response at 6 months. Moreover, the TPO-high group was associated with lower 5-year failure-free survival rates (30% vs. 68%, P = 0.012) compared with the TPO-low group.

CONCLUSION

The measurement of TPO levels at diagnosis is useful for predicting the response to IST in children with SAA and may help in decision making.

Current management of severe acquired aplastic anemia

Overall survival in severe aplastic anemia has markedly improved in the past four decades due to advances in stem cell transplantation, immunosuppressive therapies and supportive care. Horse anti-thymocyte globulin plus cyclosporine is the standard immunosuppressive regimen in severe aplastic anemia, and often employed as initial therapy as most are not candidates for a matched related stem cell transplantation. With this regimen, hematologic response can be achieved in 60 to 70% of cases, but relapse is observed in 30 to 40% of responders and clonal evolution in 10 to 15% of patients. Efforts to improve outcomes beyond horse anti-thymocyte globulin plus cyclosporine have been disappointing, with no significant improvement in the critical parameter of hematologic response, which strongly correlates with long-term survival in severe aplastic anemia. Furthermore, rates of relapse and clonal evolution have also not improved with the development of three drug regimens or with more lymphocytotoxic therapies. Therefore, horse anti-thymocyte globulin plus cyclosporine remains the standard immunosuppression of choice as first therapy in severe aplastic anemia. Interestingly, survival has markedly improved over the years in large part due to better anti-infective therapy and more successful salvage therapies with immunosuppression and stem cell transplantation. In this review general aspects of diagnosis and management are discussed.

Paroxysmal nocturnal hemoglobinuria and telomere length predicts response to immunosuppressive therapy in pediatric aplastic anemia

Acquired aplastic anemia is an immune-mediated disease characterized by severe defects in stem cell number resulting in hypocellular marrow and peripheral blood cytopenias. Minor paroxysmal nocturnal hemoglobinuria populations and a short telomere length were identified as predictive biomarkers of immunosuppressive therapy responsiveness in aplastic anemia. We enrolled 113 aplastic anemia patients (63 boys and 50 girls) in this study to evaluate their response to immunosuppressive therapy. The paroxysmal nocturnal hemoglobinuria populations and telomere length were detected by flow cytometry. Forty-seven patients (42%) carried a minor paroxysmal nocturnal hemoglobinuria population. The median telomere length of aplastic anemia patients was -0.99 standard deviation (SD) (range -4.01-+3.01 SD). Overall, 60 patients (53%) responded to immunosuppressive therapy after six months. Multivariate logistic regression analysis identified the absence of a paroxysmal nocturnal hemoglobinuria population and a shorter telomere length as independent unfavorable predictors of immunosuppressive therapy response at six months. The cohort was stratified into a group of poor prognosis (paroxysmal nocturnal hemoglobinuria negative and shorter telomere length; 37 patients) and good prognosis (paroxysmal nocturnal hemoglobinuria positive and/or longer telomere length; 76 patients), respectively. The response rates of the poor prognosis and good prognosis groups at six months were 19% and 70%, respectively (P<0.001). The combined absence of a minor paroxysmal nocturnal hemoglobinuria population and a short telomere length is an efficient predictor of poor immunosuppressive therapy response, which should be considered while deciding treatment options: immunosuppressive therapy or first-line hematopoietic stem cell transplantation. The trial was registered in www.umin.ac.jp with number UMIN000017972.

The role of paroxysmal nocturnal hemoglobinuria clones in response to immunosuppressive therapy of patients with severe aplastic anemia

Whether paroxysmal nocturnal hemoglobinuria (PNH) clone in aplastic anemia (AA) is a prognostic factor to immunosuppressive therapy is a subject of debate. We evaluated hematological responses to immunosuppressive therapy (IST) in severe AA (SAA) patients with or without the presence of a PNH clone. In 97 SAA patients who received first-line IST between January and December 2011, 24 (24.7 %) had a PNH clone prior to treatment, with a median clone size of 7.82 % (range 1.19-45.46 %). The response rates to IST for patients with or without a PNH clone were 66.7 and 50.7 % (P < 0.172), 79.2 and 57.5 % (P < 0.057), and 79.2 and 67.1 % (P < 0.264) at 3, 6, and 12 months, respectively. Combined rate of complete and good partial responses differed between patients with or without a PNH clone: insignificantly at 3 months (41.7 vs. 21.9 %, P < 0.058), but significantly at 6 (66.7 vs. 31.5 %, P < 0.002) and 12 (75.0 vs. 46.6 %, P < 0.015) months. Multivariate analysis revealed that a pretreatment neutrophil count of >0.2 × 10(9)/L is indicative of a better response, while the presence of a PNH clone is predictive to a higher combined rate of complete and good partial responses. This study demonstrated that the presence of a PNH clone could predict a better hematological response instead of a higher response rate in patients with SAA.

First-line treatment for severe aplastic anemia in children: bone marrow transplantation from a matched family donor versus immunosuppressive therapy

The current treatment approach for severe aplastic anemia in children is based on studies performed in the 1980s, and updated evidence is required. We retrospectively compared the outcomes of children with acquired severe aplastic anemia who received immunosuppressive therapy within prospective trials conducted by the Japanese Childhood Aplastic Anemia Study Group or who underwent bone marrow transplantation from an HLA-matched family donor registered in the Japanese Society for Hematopoietic Cell Transplantation Registry. Between 1992 and 2009, 599 children (younger than 17 years) with severe aplastic anemia received a bone marrow transplant from an HLA-matched family donor (n=213) or immunosuppressive therapy (n=386) as first-line treatment. While the overall survival did not differ between patients treated with immunosuppressive therapy or bone marrow transplantation [88% (95% confidence interval: 86-90) versus 92% (90-94)], failure-free survival was significantly inferior in patients receiving immunosuppressive therapy than in those undergoing bone marrow transplantation [56% (54-59) versus 87% (85-90); P<0.0001]. There was no significant improvement in outcomes over the two time periods (1992-1999 versus 2000-2009). In multivariate analysis, age <10 years was identified as a favorable factor for overall survival (P=0.007), and choice of first-line immunosuppressive therapy was the only unfavorable factor for failure-free survival (P<0.0001). These support the current algorithm for treatment decisions, which recommends bone marrow transplantation when an HLA-matched family donor is available in pediatric severe aplastic anemia.

First-line immunosuppressive treatment in children with aplastic anemia: rabbit antithymocyte globulin

Immunosuppressive therapy is the treatment of choice in children with acquired severe aplastic anemia (AA) and no HLA-matched family donor. The paper presents results of a multicenter study of 63 children with AA treated with rabbit antithymocyte globulin (r-ATG) and cyclosporine A as the first line treatment in the years 1996-2012. Therapeutic effects were evaluated at Days 112, 180, and 360. At Day 112, remission was achieved in 28 out of the 63 patients (44.4 %), complete remission in 10 patients (15.9 %), and partial remission in 18 (28.5 %). At Day 180, 31 patients (49.2 %) were in remission including 15 cases in complete (23.8 %), and 16 cases in partial remission (25.4 %). One year after therapy onset, 34 patients (64.9 %) were in remission including 24 patients (38.0 %) in complete and 10 (15.9 %) in partial remission. Relapse occurred in 4 patients, from 8 months up to 2 years and 2 months after remission. One child, 5 years after remission, was diagnosed with paroxysmal nocturnal hemoglobinuria. The estimated 10-year overall survival rate and 10-year event-free survival rate were 67 % and 57 %, respectively.

Comparison of horse and rabbit antithymocyte globulin in immunosuppressive therapy for refractory cytopenia of childhood

Refractory cytopenia of childhood is the most common subtype of myelodysplastic syndrome in children. In this study, we compared the outcome of immunosuppressive therapy using horse antithymocyte globulin (n=46) with that using rabbit antithymocyte globulin (n=49) in 95 patients with refractory cytopenia of childhood and hypocellular bone marrow. The response rate at 6 months was 74% for horse antithymocyte globulin and 53% for rabbit antithymocyte globulin (P=0.04). The inferior response in the rabbit antithymocyte globulin group resulted in lower 4-year transplantation-free (69% versus 46%; P=0.003) and failure-free (58% versus 48%; P=0.04) survival rates in this group compared with those in the horse antithymocyte globulin group. However, because of successful second-line hematopoietic stem cell transplantation, overall survival was comparable between groups (91% versus 85%; P=ns). The cumulative incidence of relapse (15% versus 9%; P=ns) and clonal evolution (12% versus 4%; P=ns) at 4 years was comparable between groups. Our results suggest that the outcome of immunosuppressive therapy with rabbit antithymocyte globulin is inferior to that of horse antithymocyte globulin. Although immunosuppressive therapy is an effective therapy in selected patients with refractory cytopenia of childhood, the long-term risk of relapse or clonal evolution remains. (ClinicalTrial.gov identifiers: NCT00662090).

Prognostic value of telomere attrition in patients with aplastic anemia

The decision to pursue hematopoietic stem cell transplantation or immunosuppression as first therapy in severe aplastic anemia is currently based on age and availability of a histocompatible donor. The ability to predict hematologic response, relapse and clonal evolution could improve treatment allocation. In the past 15 years, telomeres have been implicated in clinical diseases such as aplastic anemia, pulmonary fibrosis, cirrhosis and cancer development. The clinical relevance of varying telomere lengths (TL) and/or mutations in genes of the telomerase complex (TERC, TERT) is evolving in aplastic anemia. A large retrospective analysis suggests that baseline TL associate with late events of hematologic relapse and clonal evolution in aplastic anemia patients treated initially with anti-thymocyte globulin-based therapy. Further laboratory experiments propose possible mechanistic insight into genomic instability of bone marrow cells derived from patients with critically short telomeres and/or mutation in telomerase genes. The possibility of modulating telomere attrition rate with sex hormones could positively affect clonal evolution rates in humans. This review will summarize studies in marrow failure that explore the association between telomeres and aplastic anemia outcomes.

The progression risk factors of children with transfusion-independent non-severe aplastic anemia

Non-severe aplastic anemia (NSAA) in children is a rare, idiopathic condition of bone marrow insufficiency that can resolve spontaneously, persist for months or years, or progress to severe aplastic anemia (SAA). We reviewed clinical and laboratory data of patients diagnosed with transfusion-independent non-severe aplastic anemia (NSAA) from 1996 to 2009 at the Institute of Hematology and Blood Diseases Hospital, Peking Union Medical College, and analyzed the clinical course and outcomes in these patients. NSAA was defined as bone marrow cellularity <50 % and two or three cytopenias that persisted for 6 weeks or more: absolute neutrophil count (ANC) <1.5 × 10(9)/L, absolute reticulocyte count (ARC) <40 × 10(9)/L, platelet count <100 × 10(9)/L, without meeting criteria for SAA (bone marrow cellularity <30 % and two or three cytopenias: ANC <0.5 × 10(9)/L, ARC <20 × 10(9)/L, platelet count <20 × 10(9)/L). All patients were treated with reasonable supportive care, cyclosporine A, and stanozolol (0.1 mg/kg/day). Of a total of 284 patients, 117 (41.2 %) were female, and 167 (58.8 %) were male. With a median follow-up of 43 months (range 2-196 months), 38 patients (13.4 %) progressed to transfusion-dependent NSAA and among them 26 patients (9.2 %) progressed to SAA. One hundred and ninety-eight patients (69.7 %) had persistent NSAA. Forty-eight patients (16.9 %) showed the complete resolution of NSAA. The Kaplan-Meier estimates of all patients for progression-free survival were 86 ± 2.7 % and 66 ± 7.3 % at 60 and 120 months after diagnosis, respectively. Patients with ANC <1.0 × 10(9)/L or female had a higher probability of progression to transfusion-dependent NSAA (18.5 vs. 5.4 %, respectively; p = 0.002, and 17.1 vs. 10.8 %, respectively; p = 0.022). The patients with ARC <60 × 10(9)/L or with ANC <1.0 × 10(9)/L had a higher probability of progression to SAA (11.5 vs. 3.6 %, respectively; p = 0.035, and 12.7 vs. 3.6 %, respectively; p = 0.011). A categorical risk factor analysis showed that patients with ANC <1 × 10(9)/L had a higher probability of progression to SAA (p = 0.03) and had a higher probability of progression to transfusion-dependent AA (p = 0.007). NSAA patients may be benefited from early intervention with cyclosporine A and stanozolol.

Immunosuppressive therapy without hematopoietic growth factor exposure in pediatric acquired aplastic anemia

Immunosuppressive therapy (IST) is recommended for children with acquired aplastic anemia (AA) who lack a human leukocyte antigen (HLA)-matched sibling donor for hematopoietic cell transplantation (HCT). Hematopoietic growth factors have often been included in IST supportive care, but prolonged exposure may increase the risk of secondary clonal evolution. The authors evaluated response, survival, and the incidence of clonal evolution following cyclosporine-based IST without hematopoietic growth factor exposure in a population-based pediatric cohort, identified retrospectively. Forty-five patients with a median age of 7.3 years (range 1.2-17.0 years) were included. Partial (PR) and complete (CR) response was achieved in 82% and 64%, at a median of 55 days (range 11-414 days) and 7.6 months (range 2.8-82.2 months), respectively. Patients with associated seronegative hepatitis had an increased likelihood of PR and CR on multivariate analyses (PR: hazard ratio [HR] 3.15, 95% confidence interval [CI] 1.40, 7.11; CR: HR 2.99, 95% CI 1.35, 6.62), whereas older children were less likely to achieve IST response than children younger than 5 years at diagnosis. Five- and 10-year overall survival was 96% ± 4% and 90% ± 7%, respectively, and 5-year failure-free survival was 63% ± 8%. There was no infection-related mortality, although 16.4% of patients had at least 1 episode of documented bacteremia. The 5-year cumulative incidence of relapse was 12.9% and of clonal evolution was 3.2%. The authors conclude that children with AA who receive IST without hematopoietic growth factor support have excellent response and survival outcomes and a low incidence of clonal evolution.

Efficacy of rabbit anti-thymocyte globulin in severe aplastic anemia

BACKGROUND

A combination of horse anti-thymocyte globulin and cyclosporine produces responses in 60-70% of patients with severe aplastic anemia. We performed a phase II study of rabbit anti-thymocyte globulin and cyclosporine as first-line therapy for severe aplastic anemia.

DESIGN AND METHODS

Twenty patients with severe aplastic anemia treated with rabbit anti-thymocyte globulin were compared to 67 historical control cases with matched clinical characteristics treated with horse anti-thymocyte globulin.

RESULTS

Response rates at 3, 6 and 12 months were similar for patients treated with rabbit anti-thymocyte globulin or horse anti-thymocyte globulin: 40% versus 55% (P=0.43), 45% versus 58% (P=0.44) and 50% versus 58% (P=0.61), respectively. No differences in early mortality rates or overall survival were observed. We then performed multivariable analyses of response at 6 months and overall survival and identified the presence of a paroxysmal nocturnal hemoglobinuria clone (P=0.01) and a pretreatment absolute reticulocyte count greater than 30×10(9)/L (P=0.007) as independent predictors of response and younger age (P=0.003), higher pretreatment absolute neutrophil (P=0.02) and absolute lymphocyte counts (P=0.03) as independent predictors of overall survival. None of the immunogenetic polymorphisms studied was predictive of response to immunosupressive therapy.

CONCLUSIONS

Despite reports suggesting differences in biological activity of different anti-thymocyte globulin preparations, rabbit and horse anti-thymocyte globulin appear to have a similar efficacy for up-front treatment of severe aplastic anemia. Clinicaltrial.gov: NCT01231841).

Predicting response to immunosuppressive therapy in childhood aplastic anemia

In aplastic anemia, predictive markers of response to immunosuppressive therapy have not been well defined. We retrospectively evaluated whether clinical and laboratory findings before treatment could predict response in a pediatric cohort from the multicenter AA-97 study in Japan. Between 1997 and 2006, 312 newly diagnosed children were enrolled and treated with a combination of antithymocyte globulin and cyclosporine. In multivariate analyses, lower white blood cell count was the most significant predictive marker of better response; patients with white blood cell count less than 2.0×10(9)/L showed a higher response rate than those with white blood cell count of 2.0×10(9)/L or more (P=0.0003), followed by shorter interval between diagnosis and therapy (P=0.01), and male sex (P=0.03). In conclusion, pre-treatment clinical and laboratory findings influence response to therapy. The finding that response rate worsens with increasing interval between diagnosis and treatment highlights the importance of prompt immunosuppressive therapy for patients with aplastic anemia.