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.     

Danazol therapy for aplastic anemia refractory to immunosuppressive therapy

Although there are anecdotal reports of the efficacy of danazol in the treatment of aplastic anemia (AA), there has been no systematic study to clarify its efficacy and toxicity. Therefore, we assessed the efficacy of danazol for treatment of patients with AA refractory to immunosuppressive therapy (IST) and those who relapsed after IST, in a prospective clinical trial. Sixteen patients (12 males and four females; six severe cases and 10 moderate cases) were treated with 300 mg of danazol daily for 12 weeks. All patients completed the treatment period without occurrence of severe toxicity. Three female patients achieved partial remission, whereas only two of the 12 male patients did so. None of the responders had shown a response to previous IST or an increase in the percentage of paroxysmal nocturnal hemoglobinuria (PNH)-type cells which are known to be a marker for a good response to IST. These findings indicate that danazol is effective for a subset of AA patients, and particularly for female patients with AA refractory to IST.     

The optimal immunosuppressive therapy for aplastic anemia

Immunosuppressive treatment (IST) has been the most effective therapeutic modality for patients with aplastic anemia (AA) who are not eligible for allogeneic stem cell transplantation from HLA-matched siblings because of donor unavailability, old age, or comorbidities. The combination of horse anti-thymocyte globulin (ATG) with cyclosporine A (CsA) has shown satisfactory results for these patients, and so it has been regarded as the standard IST regimen. However, treatment failure including unresponsiveness, relapse, and occurrence of clonal evolution remains a major problem, although the results of IST have been improved in the past two decades. Many studies have been conducted to overcome these problems; however, they have yet to show any satisfactory results. This review will discuss immune-mediated pathophysiology of AA, which is associated with therapeutic targets of immunosuppressive agents and clinical outcomes of most commonly used IST regimens. Several trials to improve IST including the addition of other immunosuppressive agents or growth factors to standard IST regimen, comparison between horse ATG/CsA and rabbit ATG/CsA as first-line treatment, and promising alternative agents including alemtuzumab and eltrombopag will also be discussed, focusing on recently published literatures.     

Severe aplastic anemia with autoimmune thyroiditis showing no hematological response to intensive immunosuppressive therapy

A 39-year-old woman with severe aplastic anemia (SAA) was transferred to our institution. She also had autoimmune thyroiditis with several positive autoantibodies. Clonal or oligoclonal T-cell proliferation was demonstrated by determining the size distribution of the complementarity-determining region 3 (CDR3) of T-cell receptor beta-chain (TCR-Vbeta) subfamilies in the patient's bone marrow and peripheral blood cells. The results suggested that hematopoiesis was suppressed by immune-mediated mechanisms. Immunosuppressive therapy for SAA using cyclosporin A (CsA) alone or concurrent CsA and antithymocyte globulin (ATG) failed to induce a hematological response. The intensity of the autoantibodies, however, partially decreased during this period. In addition, the CD4/CD8 ratio was inverted after immunosuppressive therapy. These observations indicate that, in a subset of SAA, immune-mediated hematopoietic suppression cannot be successfully treated by conventional immunosuppressive therapy, even though a substantial improvement in the underlying immunological changes can be achieved. Other therapies such as hematopoietic stem cell transplantation or more intensified repeated ATG therapy may be necessary for such patients.     

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.     

Hepatitis-associated aplastic anemia: successful outcome following immunosuppressive therapy.

Hepatitis-associated aplastic anemia is an uncommon variant seen in young, previously healthy individuals. The pancytopenia follows hepatitis by a few weeks and is usually severe and prolonged. Bone marrow transplantation remains the cornerstone of therapy. However, immunosuppressive therapy has been found to be effective. We report an 8-year-old girl who had non-A, B, C and E hepatitis-associated severe aplastic anemia. She became transfusion-independent and had consistent, albeit incomplete recovery after immunosuppressive therapy with antithymocyte globulin and cyclosporine.     

Predictive factors for cure after immunosuppressive therapy of aplastic anemia

In a previous study, we evaluated efficacy of repeated antilymphocyte globulin (ALG) treatment for patients with severe aplastic anemia not responding to an initial ALG treatment or relapsing after initial response to ALG. We now searched in the same cohort of patients for differences between patients who responded to treatment and remained free of complications and those who relapsed or developed a clonal complication. From 107 patients surviving for more than 1 year after immunosuppression, 34 remained free from complications after the first course of ALG, and 73 presented an event defined as relapse of aplastic anemia, development of a clonal complication such as paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome or leukemia, or appearance of a solid tumor. We compared these two groups for survival, clinical performance and blood counts during follow-up. Survival probability was 93% for the event-free patients, and 55% for the patients with a complication event (p = 0.0003). Event-free patients had a higher incidence of complete remission (71%), were more often free of immunosuppressive treatment (79%) and independent of transfusions (100%), and had a higher Karnofsky score (91% with a score > or =90%) as compared to the group with events (29, 37, 67, 48%; p < or = 0.0002). At 1 and 3 years, event-free patients had significantly higher leukocyte and neutrophil counts, as compared to patients with a complication (p < 0.05). However, at 3 and 5 years, event-free patients had borderline higher platelet counts (p = 0.056, p = 0.078) and hemoglobin (p = 0. 097, p = 0.061). The coefficient of variation as an expression of the variability of the results in each group was systematically lower at 3, 5 and 10 years in the group of event-free patients. Despite some differences between the two groups, our data support the hypothesis that patients with long-lasting remissions should not be considered as definitively cured of aplastic anemia.     

Peripheral blood lymphocyte telomere length as a predictor of response to immunosuppressive therapy in childhood aplastic anemia

Predicting the response to immunosuppressive therapy could provide useful information to help the clinician define treatment strategies for patients with aplastic anemia. In our current study, we evaluated the relationship between telomere length of lymphocytes at diagnosis and the response to immunosuppressive therapy in 64 children with aplastic anemia, using flow fluorescence in situ hybridization. Median age of patients was ten years (range 1.5–16.2 years). Severity of the disease was classified as very severe in 23, severe in 21, and moderate in 20 patients. All patients were enrolled in multicenter studies using antithymocyte globulin and cyclosporine. The response rate to immunosuppressive therapy at six months was 52% (33 of 64). The probability of 5-year failure-free survival and overall survival were 56% (95% confidence interval (CI): 41–69%) and 97% (95%CI: 87–99%), respectively. Median telomere length in responders was −0.4 standard deviation (SD) (−2.7 to +3.0 SD) and −1.5 SD (−4.0 to +1.6 (SD)) in non-responders (P<0.001). Multivariate analysis showed that telomere length shorter than −1.0 SD (hazard ratio (HR): 22.0; 95%CI: 4.19–115; P<0.001), platelet count at diagnosis less than 25×10⁹/L (HR: 13.9; 95%CI: 2.00–96.1; P=0.008), and interval from diagnosis to immunosuppressive therapy longer than 25 days (HR: 4.81; 95%CI: 1.15–20.1; P=0.031) were the significant variables for poor response to immunosuppressive therapy. Conversely to what has been found in adult patients, measurement of the telomere length of lymphocytes at diagnosis is a promising assay in predicting the response to immunosuppressive therapy in children with aplastic anemia.     

Predicting response to immunosuppressive therapy and survival in severe aplastic anaemia

Horse anti-thymocyte globulin (h-ATG) and ciclosporin are the initial therapy for most patients with severe aplastic anaemia (SAA), but there is no practical and reliable method to predict response to this treatment. To determine whether pretreatment blood counts discriminate patients with SAA who have a higher likelihood of haematological response at 6 months to immunosuppressive therapy (IST), we conducted a single institution retrospective analysis on 316 SAA patients treated with h-ATG-based IST from 1989 to 2005. In multivariate analysis, younger age, higher baseline absolute reticulocyte count (ARC), and absolute lymphocyte count (ALC) were highly predictive of response at 6 months. Patients with baseline ARC ≥ 25 × 10⁹/l and ALC ≥ 1 × 10⁹/l had a much greater probability of response at 6 months following IST compared to those with lower ARC and ALC (83% vs. 41%, respectively; P  < 0·001). This higher likelihood of response translated to greater rate of 5-year survival in patients in the high ARC/ALC group (92%) compared to those with a low ARC/ALC (53%). In the era of IST, the baseline ARC and ALC together serve as a simple predictor of response following IST, which should guide in risk stratification among patients with SAA.     

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??1 in the first 28 days (p??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?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.     

Ticlopidine-induced aplastic anemia and quick recovery with G-CSF: case report and literature review

We report here a case of ticlopidine-induced aplastic anemia that responded to G-CSF and review the literature. An 83-year-old woman was started on ticlopidine for coronary artery disease after an episode of upper gastrointestinal bleeding secondary to aspirin. She developed aplastic anemia seven weeks after initiation of ticlopidine. She was hospitalised and received empiric antibiotic therapy and granulocyte colony stimulating factor (G-CSF). Her bone marrow started to recover quickly, and white blood cell and platelet counts returned to normal within three weeks. A review of medical literature revealed 20 similar cases of ticlopidine-induced aplastic anemia resulting in death in seven cases. G-CSF has been used previously with variable success. Ticlopidine is associated with serious, sometimes fatal hematological side effects. This risk should be seriously taken into consideration when prescribing ticlopidine. G-CSF may be helpful in the treatment of ticlopidine-induced aplastic anemia.     

Abnormal cytogenetic clones in patients with aplastic anaemia: response to immunosuppressive therapy

We report the response to immunosuppressive therapy with antithymocyte globulin (ATG) and cyclosporin or oxymetholone in 13 cases of aplastic anaemia (AA) with an abnormal cytogenetic clone detected at or sometime after diagnosis. Blood and bone marrow examination showed no distinctive morphological features of myelodysplasia (MDS) at diagnosis. Haematological response occurred promptly in eight cases; the remainder responded after additional immunosuppression with or without oxymetholone. Three patients had a late relapse of AA, treated successfully by allogeneic bone marrow transplantation in one; the others responded to oxymetholone. Transformation to MDS or acute leukaemia was not observed after a median follow-up of 4.1 years (range 1.2-11.2). In four patients the cytogenetic clone disappeared after treatment.     

Correlation of two in vitro tests with clinical response to immunosuppressive therapy in 54 patients with severe aplastic anemia

Two in vitro tests were applied to 54 consecutive patients with severe aplastic anemia who were treated in Seattle with antithymocyte globulin. In the first test, peripheral blood mononuclear cells were collected from each patient before antithymocyte globulin therapy and then treated with a panel of monoclonal antibodies and complement. The treated peripheral blood mononuclear cells were assayed for erythroid burst-forming units (BFU-E). This test was designed to determine whether removing various subpopulations of peripheral blood mononuclear cells would increase the number of detectable BFU-E. In the second test, peripheral blood was collected within 48 hr after completion of antithymocyte globulin therapy, and cells were immediately assayed for BFU-E without any further treatment. Data from both tests were analyzed to determine whether the in vitro results correlated with patient response to therapy. Binary logistic regression analyses indicate that a modest correlation (p = 0.04) exists between test 1 in vitro results and patient response to therapy. However, the strength of this association appears to decrease as the interval between diagnosis and treatment increases. In contrast, test 2 had a very significant correlation (p = 0.001) with response to therapy among patients diagnosed more than 1 mo prior to treatment, whereas such an association was not apparent among patients treated within 1 mo of diagnosis.     

Hairy cell leukemia responsive to anti-thymocyte globulin used as immunosuppressive therapy for aplastic anemia

Hairy cell leukemia (HCL) is occasionally misdiagnosed as aplastic anemia when only a few leukemic cells are present in the circulation. Here, we describe a patient with HCL who initially presented with pancytopenia and received a diagnosis of aplastic anemia. The patient was treated with immunosuppressive therapy including cyclosporine A and anti-thymocyte globulin (ATG). No blood cell transfusion was required for approximately 3 years after ATG therapy. She was referred to our hospital because of an abdominal mass and requiring periodic blood transfusions. A bone marrow biopsy at this time revealed proliferation of lymphocytes with a fried egg appearance and an increase in reticulin fibers that are typical findings of HCL. It is notable that our patient with a presumably long history of HCL and an increase in marrow reticulin fibers showed good recovery of hematopoiesis after cladribine therapy. Some HCL patients may receive an initial diagnosis of aplastic anemia and may show a good response to ATG masking the underlying HCL.