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

Background: Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) plus cyclosporine (CSA) is standard therapy in patients with severe aplastic anemia (SAA) who do not have an available HLA‐matched sibling donor. Methods and patients: The current study aimed to determine the predictive factors for response to IST in patients with SAA and to identify prognostic factors following IST. A total of 62 patients diagnosed with SAA who received IST with either rabbit ATG (n = 33) or horse ATG (n = 29) plus CSA between October 1994 and December 2007 were included. Results: With a median follow‐up duration of 60.5 months, complete response and overall response were estimated to be 31% and 53%, respectively. The 4 yr overall survival rate was 75 ± 6%. In terms of predicting the response to IST, neutrophil counts above 0.3 × 10⁹/L prior to IST were the only significant predictive factor (P = 0.02). Survival following IST was significantly different in favor of both the group showing high absolute reticulocyte counts (ARC) above 10.9 × 10⁹/L prior to IST (P = 0.004) and the group achieving any response following IST (P = 0.002). Conclusions: Pre‐IST neutrophil counts might predict the response to IST, while absolute ARCs prior to IST and response status after IST could be prognostic factors following IST.     

Cyclophosphamide and other new agents for the treatment of severe aplastic anemia

Severe aplastic anemia (SAA) has a poor prognosis in the absence of treatment. Current accepted therapeutic strategies include allogeneic stem-cell transplantation and immunosuppression, both resulting in long-term survival in the majority of patients. Although human leukocyte antigen (HLA)-matched sibling stem-cell transplantation is highly effective, the 25% probability of finding a suitable sibling donor within a family renders this approach available to only a minority of patients. Transplantation using HLA-matched, unrelated donors carries a high risk of treatment failure along with considerable toxicity. While combined immunosuppression with both antithymocyte globulin (ATG) and cyclosporine A (CSA) produces hematologic improvement in most patients, relapse is common. Late evolution of aplastic anemia to other serious hematologic disorders, including paroxysmal nocturnal hemoglobinuria (PNH), myelodysplasia, and acute leukemia, is also a significant problem following treatment with ATG/CSA. Recently, results of immunosuppression in SAA with another potent immunosuppressive agent, cyclophosphamide, were reported in a small number of patients. The overall response rate was similar to that seen with ATG/CSA, but relapse and late clonal disease were not observed during a long period of follow-up. A larger randomized trial comparing sustained hematologic response rates to either conventional immunosuppression with ATG/CSA or high-dose cyclophosphamide and CSA is now underway; secondary end points include response duration, event-free survival, and overall survival. Additionally, a number of protocols designed to test the efficacy of alternative immunosuppressive or immunomodulatory agents are being developed.     

Predictors of early mortality after rabbit antithymocyte globulin as first-line treatment in severe aplastic anemia

Despite being recommended as first-line immunosuppressive therapy in severe aplastic anemia (SAA), horse antithymocyte globulin (ATG) is still unavailable in many countries outside the USA. Rabbit ATG is more lymphocytoxic than horse ATG, and this might result in a higher incidence of severe infections and early mortality. This study was designed to identify the risk factors for early mortality and overall survival (OS) after rabbit ATG in patients with SAA. We retrospectively reviewed 185 patients with SAA who underwent rabbit ATG and cyclosporine. The incidence of death in 3 months following rabbit ATG therapy was 15.1% (28/185). Early mortality was mainly related to infectious complications, despite adequate antibiotic and/or antifungal treatment. Age > 35 years (odds ratio [OR] 5.06, P = 0.001) and baseline absolute neutrophil count (ANC) ≤ 0.1 × 10⁹/L (OR 7.64, P < 0.001) were independent risk factors for early mortality after immunosuppressive therapy with this agent. Hematological response at 6 months was observed in only 29.7% of all patients. OS at 1 year after rabbit ATG was 75.3%; and age > 35 years (OR 1.88, P = 0.03), baseline ANC ≤ 0.1 × 10⁹/L (OR 2.65, P < 0.001), and lack of response to rabbit ATG (OR 11.40, P < 0.001) were independently associated with mortality. Alternative strategies are needed for the treatment of SAA patients in countries were horse ATG is unavailable, particularly for those at high risk for early mortality after rabbit ATG due to a higher age and very low pre-treatment neutrophil count.     

Treatment of adults with severe aplastic anemia: primary therapy with antithymocyte globulin (ATG) and rescue of ATG failures with bone marrow transplantation.

PURPOSE: To evaluate a policy of immunosuppression with antithymocyte globulin (ATG) as primary therapy for adults with severe aplastic anemia (SAA) regardless of the availability of an HLA-identical bone marrow donor. PATIENTS AND METHODS: Thirty-one consecutive adults with SAA who satisfied the age criteria for allogeneic bone marrow transplantation (BMT) (age less than 51 years) were treated with ATG 20 mg/kg/day for 10 days along with high-dose corticosteroids. Patients with an HLA-identical donor received a transplant if they did not respond to ATG or if they developed life-threatening complications during or soon after ATG administration. Eight patients with no response to ATG were also treated with oral cyclosporine 12.5 mg/kg/day. RESULTS: Eleven patients had a complete and five a partial response to ATG; two patients improved with cyclosporine treatment, resulting in an overall response rate of 58% to immunosuppression. Nine of 14 patients with donors received a BMT: seven because they did not respond to ATG and two because of serious infections. Seven grafts were obtained from related and two from unrelated donors. There was no significant difference in survival between those with and without a related HLA-identical donor (log-rank p value = 0.969). At a median follow-up of 58 months, 26 of 31 are alive with an actuarial survival of 80% at 5 years. Two patients died of infection, two died from complications of BMT, and one remains transfusion-dependent. One patient died of refractory leukemia at 30 months; one patient relapsed with hypoplasia 95 months after initial therapy with ATG. He showed a complete response to treatment with cyclosporine. No other late hematologic events have occurred. CONCLUSIONS: This treatment approach resulted in the restoration of hematopoiesis and independence from transfusion in 80% of patients with SAA entered into the study. The efficacy of allogeneic BMT in salvaging cases in which ATG failed does not appear to be compromised. Follow-up for the development of clonal hematologic disorders remains an important part of this treatment policy.     

非清髓性造血干细胞移植治疗血液病预处理中ATG／ALG的应用及作用

目的：探讨抗胸腺细胞球蛋白（ATG）和抗淋巴细胞球蛋白（ALG）在血液病非清髓性异基因造血干细胞移植中的作用，以及ATG/ALG的毒副作用，对移植并发症的影响。方法：以ATG／ALG为基础降低化疗剂量的非清髓性预处理方案，对16例恶性血液病、17例重型再生障碍性贫血（SAA）实施骨髓、骨髓加外周血造血干细胞或脐血造血干细胞移植；对5例恶性血液病实施逐渐增加剂量的供者淋巴细胞输注（DLI），1例S从实行供者干细胞输注（DSI）。GVHD的预防：恶性血液病采用环孢菌素A联合短程甲氨喋呤，SAA患者采用CSA联合甲泼尼龙。采用糖皮质激素和甾体类消炎药等防治ATG／ALG毒副作用和并发症。结果：3例患者在移植后早期感染死亡。其余30例患者恢复造血功能，ANC〉0．5×10^8/L和PLT〉20×10^9／l平均时间为12．2（3-35）d和20．1（5～80）d。移植后7例为供者型完全嵌合体（CC），3例无植入证据；23例为混合性嵌合体（MC），其中7例逐渐转为CC，6倒是在DLI或者DSI后实现MC向CC转变。移植后早期均无aGVHD，3～8次DLI并发Ⅰ度aGVHD1例、Ⅱ度aGVHD3例，2例皮肤局限型cGVHD、2例为广泛型cGVHD。并发严重的细菌感染3例、病毒感染4例、真菌感染5例。ATG／ALG使用过程中全部出现寒战、发热症状，大部分出现皮疹、一过性血压下降、少数出现一过性心律不齐，经积极防治不需中断治疗。结论：ATG／ALG促进异基因造血干细胞的植入，延迟和减少GVHD的发生率并降低严重程度．是否增加病毒、真菌感染的机会有待进一步观察。     

Long-term outcome of aplastic anemia in adults treated with antithymocyte globulin: comparison with bone marrow transplantation

The outcome of 155 adult aplastic anemia (AA) patients treated with antithymocyte globulin (ATG, Upjohn, Kalamazoo, MI) at University of California, Los Angeles from 1977 to 1988 was evaluated. The median survival of the 146 patients who did not undergo bone marrow transplantation was 5.6 years, with 49% +/- 4% surviving more than 6 years. The most important predictor of survival was positive response to ATG (P < 0.001), which was observed in 48% of patients. Among pretreatment variables, disease severity was the best predictor of survival. Patients with moderate AA (MAA) had significantly better survival than those with severe (SAA) or very severe (VSAA) disease (P = 0.04). The 6-year actuarial survival rates of the three groups were 71% +/- 9%, 48% +/- 7% and 38% +/- 7%, respectively. Cox regression analysis found disease severity to be the only pretreatment variable significantly associated with survival (P = .02). Patient age, sex, disease etiology, concurrent treatment with androgens, or duration of ATG therapy were not associated with differences in survival or response to ATG. Late clonal hematologic complications (ie, myelodysplasia, acute myelogenous leukemia) were observed in 5 of the 77 patients followed for more than 2 years after ATG treatment. In addition, one case of non-Hodgkin's lymphoma and three solid tumors occurred in the ATG-treated patients. The survival of 56 ATG-treated patients with SAA or VSAA between the ages of 16 and 43 did not differ significantly from that of 55 adult AA patients who underwent bone marrow transplant (BMT) during the same time period (P = 0.6). However, 6-year survival rates improved from 43% for patients transplanted before 1984, to 72% for those who underwent BMT between 1984 and 1989. In contrast, there was no difference in the survival rates of patients treated with ATG during these two time periods (46% v 45%, respectively). The results suggest a superior long-term outcome for adult patients with SAA treated with BMT rather than with ATG alone, using current protocols.     

Immunosuppressive therapy for aplastic anemia in children: a more severe disease predicts better survival

Severe acquired aplastic anaemia (SAA) is a life-threatening disease characterized by pancytopenia and hypoplastic bone marrow. Autologous T lymphocytes are thought to cause bone marrow failure by immune-mediated excessive apoptosis of stem and progenitor cells. The disease is subclassified into a severe (neutrophil count, > 0.2 x 10(9)/L [> 200/microL]) and a very severe (< 0.2 x 10(9)/L [< 200/microL]) (vSAA) form. We report the results of a prospective multicenter trial with a combined immunosuppressive regimen of cyclosporin A (CSA), anti-thymocyte globulin (ATG) and, in cases with neutrophil counts fewer than 0.5 x 10(9)/L (< 500/microL), granulocyte colony-stimulating factor (G-CSF) for treatment of SAA in children. Children with vSAA showed a higher rate of complete response than did children with SAA (68% versus 45%; P = .009), as well as better survival (93% versus 81%; P < .001). Thus, in children with SAA a more severe disease stage at diagnosis indicates a favorable outcome with immunosuppressive therapy.     

Risk Factors for Cytomegalovirus Retinitis Following Bone Marrow Transplantation From Unrelated Donors in Patients With Severe Aplastic Anemia or Myelodysplasia

Two cases of cytomegalovirus (CMV) retinitis following bone marrow transplantation (BMT) from unrelated donors are reported. 1 patient had been treated for severe aplastic anemia (SAA) and the other for hypoplastic myelodysplastic syndrome (MDS). Because first line therapy with antithymocyte globulin (ATG) and cyclosporin A (CsA) had failed, BMT was performed following a conditioning regimen of ATG, cyclophosphamide, and total lymphoid irradiation. Treatment for CMV retinitis was successfully carried out with gancyclovir (systemic and intraocular injection), foscarnet, and photocoagulation (Case 1) and gancyclovir and foscarnet (Case 2). Both patients also developed Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD). We compared these 2 cases with 14 SAA patients who did not develop CMV retinitis after BMT using marrow from either HLA-identical siblings (n = 9) or from unrelated donors (n = 5). Unlike the retinitis patients, the latter 5 patients received ATG only once. The retinitis patients had significantly lower CD4+ T-cell levels in their peripheral blood than the 14 patients who did not develop CMV retinitis. We believe that repeated treatment with ATG and transplantation from unrelated donors may lead to immune dysfunction that could increase the likelihood of CMV retinitis, as well as LPD. For such BMT patients, regular ophthalmic examinations and careful testing for CMV antigenemia are recommended.     

Prospective randomized multicenter study comparing cyclosporin alone versus the combination of antithymocyte globulin and cyclosporin for treatment of patients with nonsevere aplastic anemia: a report from the European Blood and Marrow Transplant (EBMT) Severe Aplastic Anaemia Working Party

We report the results of the first prospective randomized multicenter study of immunosuppressive treatment in patients with previously untreated nonsevere aplastic anemia (AA) as defined by a neutrophil count of at least 0.5 x 10(9)/L and transfusion dependence. Patients were randomized to receive cyclosporin (CSA) alone or the combination of horse antithymocyte globulin ([ATG] Lymphoglobuline; Merieux, Lyon, France) and CSA. The endpoint of the study was the hematologic response at 6 months. One hundred fifteen patients were randomized and assessable with a median follow-up period of 36 months; 61 received CSA and 54 ATG and CSA. In the CSA group, the percentage of complete and partial responders was 23% and 23%, respectively, for an overall response rate of 46%. A significantly higher overall response rate of 74% was found in the ATG and CSA group, with 57% complete and 17% partial responders (P =. 02). Compared with CSA alone, the combination of ATG and CSA resulted in a significantly higher median hemoglobin level and platelet count at 6 months. Fewer patients required a second course of treatment before 6 months due to a nonresponse. In the CSA group, 15 of 61 (25%) patients required a course of ATG before 6 months because of disease progression, compared with only 3 of 54 (6%) in the ATG and CSA group. The survival probabilities for the two groups were comparable, 93% (CSA group) and 91% (ATG and CSA group), but at 180 days, the prevalence of patients surviving free of transfusions, which excluded patients requiring second treatment because of nonresponse, death, disease progression, or relapse, was 67% in the CSA group and 90% in the ATG and CSA group (P =.001). We conclude that the combination of ATG and CSA is superior to CSA alone in terms of the hematologic response, the quality of response, and early mortality, and a second course of immunosuppression is less frequently required.     

Anti-Thymocyte Globulin Treatment for Aplastic Anemia

20 patients with severe aplastic anemia were treated with anti-thymocyte globulin (ATG), 6 of them in combination with haplo-identical bone marrow. 7 patients (35%) showed a good clinical response within 6 months; they were off transfusions and had ≥ 0.8 times 10⁹/1 neutrophils. ATG had the greatest effect on red-cell production and the least on platelet production. The hematological recovery after ATG could not be predicted from the bone-marrow histology, CFU-c growth, or clinical data. However, patients with strong HLA antibodies seemed to respond more often. The actuarial survival was 55% at 5 years. Under intensive supportive care, even 7 out of 12 non-responders were alive after 1 year. ATG appears to be a useful form of therapy for patients with severe aplastic anemia who are not candidates for bone-marrow transplantation.     

Multicenter randomized study comparing cyclosporine-A alone and antithymocyte globulin with prednisone for treatment of severe aplastic anemia.

We report the results of a randomized multicenter study comparing the efficacy of antithymocyte globulin (ATG) with that of cyclosporin A (CsA) as first-line therapy for severe aplastic anemia (SAA). Patients were randomized to receive ATG and prednisone (PDN) or CsA; hematologic response and toxicity were compared. At 3-month evaluation, patients who had no or minimal response received the alternative therapy to assess the value of a sequential immunosuppressive therapy for treatment of severe aplastic anemia. One hundred nineteen patients were randomized; 25 were excluded, of whom 3 were misdiagnosed and 22 did not follow the cross-over protocol. Ninety-four patients were analyzed; 46 received CsA, and 48 received ATG-PDN. The actuarial survival was 66.7%, with a median follow-up time of 19 months. There was no significant difference in survival between the groups with, at 3 months, an actuarial survival of 88% in the CsA group and 75% in the ATG group (NS); at 12 months, it was 70% in the CsA group and 64% in the ATG group (NS). The percentage of complete and partial response was 11.6% and 16%, respectively, at 3 months, and 31.6% and 30%, respectively, at 12 months (NS). The main prognostic factor was the absolute neutrophil count (ANC) at entry: Patients with ANC less than 0.2 x 10(9)/L had a significantly lower survival as compared with patients with more than 0.2 x 10(9)/L ANC (P = .0001). At 12 months, 62 evaluable patients were alive, with a complete or partial response in 36 patients. Patients who had responded to the first treatment had a better recovery of bone marrow failure than those who had sequential immunosuppression. The main complication was infection, which was more often observed and more often lethal during ATG and PDN therapy. In this study, initial treatment of SAA with either CsA or ATG-PDN followed by cross-over therapy for nonresponders produced comparable response and survival rates.     

Horse antithymocyte globulin as salvage therapy after rabbit antithymocyte globulin for severe aplastic anemia

The effectiveness of salvage therapy for aplastic anemia patients unresponsive to initial rabbit antithymocyte globulin (r‐ATG) or cyclophosphamide is not known. We investigated the administration of standard horse ATG (h‐ATG) plus cyclosporine (CsA) in patients who were refractory to initial r‐ATG/CsA (n = 19) or cyclophosphamide/CsA (n = 6) (registered at clinicaltrials.gov as NCT00944749). The primary endpoint was hematologic response at 3 months and was defined as no longer meeting the criteria for severe aplastic anemia. Of the 19 patients who received r‐ATG as initial therapy, 4 (21%) achieved a hematologic response by 3 months, and of the 6 patients who received cyclophosphamide, only 1 (17%) responded by 6 months. Among the responders there were no cases of relapse, and in nonresponders 2 patients evolved to monosomy 7. The overall survival for the cohort at 3 years was 68% (95% CI, 50–91%). These results suggest that only a minority can be successfully salvaged after receiving as first therapy either r‐ATG or cyclophosphamide. Although h‐ATG may be utilized in the salvage setting, the overall response rate probably will be lower than when h‐ATG is used as initial treatment. Am. J. Hematol. 89:467–469, 2014. © Published 2014.     

Restoration of immunity and reactivation of hepatitis B virus after immunosuppressive therapy in a patient with severe aplastic anaemia

We recently treated a patient with severe aplastic anaemia (SAA) who also had chronic hepatitis B virus (HBV) infection. The HBV serological status at the time of diagnosis of SAA was HBsAg(+) and HBeAg(+). Subsequent analysis of the precore region of HBV DNA showed wild-type. He received anti-thymocyte globulin (ATG) and cyclosporin A (CsA) therapy twice. After each course of ATG infusion and during CsA therapy he developed lymphopenia for 1 and 2.5 months, respectively. His serum alanine aminotransferase (ALT) became normalized during the period of lymphopenia, but the serum HBV viral load increased. When his peripheral lymphocytes count recovered, his ALT became elevated again. Lamivudine was effective to normalize his elevated ALT and suppress viral replication. The phenomenon observed in this case supports the prevailing notion that hepatitis B flare-up in HBV carriers after chemotherapy is caused by an immune-mediated mechanism. Meanwhile, this is the first documented case of SAA who developed HBV reactivation upon recovery of lymphopenia after immunosuppressive therapy. This also highlights the necessity of pre-emptive therapy with lamivudine in SAA/HBsAg(+) patients to receive immunosuppressive therapy with ATG/CsA.     

A randomized controlled study in patients with newly diagnosed severe aplastic anemia receiving antithymocyte globulin (ATG), cyclosporine, with or without G-CSF: a study of the SAA Working Party of the European Group for Blood and Marrow Transplantation

We evaluated the role of granulocyte colony-stimulating factor (G-CSF) in patients with severe aplastic anemia (SAA) treated with antithymocyte globulin (ATG) and cyclosporine (CSA). Between January 2002 and July 2008, 192 patients with newly diagnosed SAA not eligible for transplantation were entered into this multicenter, randomized study to receive ATG/CSA with or without G-CSF. Overall survival (OS) at 6 years was 76% ± 4%, and event-free survival (EFS) was 42% ± 4%. No difference in OS/EFS was seen between patients randomly assigned to receive or not to receive G-CSF, neither for the entire cohort nor in subgroups stratified by age and disease severity. Patients treated with G-CSF had fewer infectious episodes (24%) and hospitalization days (82%) compared with patients without G-CSF (36%; P = .006; 87%; P = .0003). In a post hoc analysis of patients receiving G-CSF, the lack of a neutrophil response by day 30 was associated with significantly lower response rate (56% vs 81%; P = .048) and survival (65% vs 87%; P = .031). G-CSF added to standard ATG and CSA reduces the rate of early infectious episodes and days of hospitalization in very SAA patients and might allow early identification of nonresponders but has no effect on OS, EFS, remission, relapse rates, and mortality. This study was registered at www.clinicaltrials.gov as NCT01163942.     

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.     

Allogeneic stem cell transplantation using alemtuzumab-containing regimens in severe aplastic anemia

Alemtuzumab, a humanized anti-CD52, IgG1 monoclonal antibody, is used to reduce graft-versus- host disease (GVHD) and aid engraftment after allogeneic haemopoietic stem cell transplant (HSCT). Its associated low incidence of GVHD makes it an attractive alternative to anti-thymocyte globulin (ATG) in transplant conditioning regimen for severe aplastic anaemia (SAA). We have reviewed the use of alemtuzumab-based conditioning regimen for HSCT in SAA and show that it results in sustained haematological engraftment, a very low incidence of chronic GVHD without an increase in viral infections. Intriguingly, alemtuzumab appears to induce tolerance post-HSCT with the findings of stable mixed T cell chimerism with full donor myeloid chimerism and the absence of chronic GVHD, and which persist on withdrawal of post-graft immunosuppression. Finally, its low toxicity profile may permit future application of HSCT to older patients with SAA who fail to respond to immunosuppressive therapy.     

Treatment of severe aplastic anaemia with anti-thymocyte globulin

Ten patients (9 adults, 1 child) with severe aplastic anaemia (SAA) were treated with anti-thymocyte globulin (ATG). All patients developed serum sickness. No long-term adverse sequelae attributable to ATG were noted. Fifty percent of patients are alive at 1 year post-ATG. One patient received an allogeneic bone marrow transplant because of failure to respond to ATG. One long-term survivor is severely thrombocytopenic and requires support, and one patient has mild thrombocytopenia requiring oxymetholone therapy.     

Prospective randomized trial comparing two doses of rabbit anti-thymocyte globulin in patients with severe aplastic anaemia

The treatment of choice for patients with severe aplastic anaemia (SAA) includes immunosuppressive therapy (IST) with anti-thymocyte globulin (ATG) and ciclosporin A. However, the optimal dose for rabbit ATG has yet to be established. We herein report the first prospective, randomized, multicentre study comparing two doses of rabbit ATG in patients with SAA. Patients with SAA who required initial IST in Japan (n = 89), China (n = 85) and Korea (n = 48) were enrolled between May 2012 and October 2017. A 1:1 block randomization was employed for two doses of rabbit ATG. In total, 222 patients were randomized, with 112 patients receiving 2·5 mg/kg and 110 receiving 3·5 mg/kg of rabbit ATG for 5 days. The primary endpoint was the haematological response at day 180. After 6 months, no significant difference in response rates was observed between the 2·5 and 3·5 mg/kg groups (49% vs. 48%, P = 0·894). Overall survival at 3 years was similar between the two groups [85% (95% confidence interval [CI], 76%−91%) vs. 91% (95% CI, 82%−96%); P = 0·107]. The current study revealed no significant differences in the efficacy and safety between the 2·5 and 3·5 mg/kg doses of rabbit ATG in patients with SAA. Trial registration: UMIN000011134.     

Haematopoietic and immunologic abnormalities in severe aplastic anaemia patients treated with anti-thymocyte globulin

Summary. Thirty-five patients with severe aplastic anaemia (SAA) were extensively evaluated 0.3-12.4 years (median 3.8) after anti-thymocyte globulin (ATG) treatment. All but one were transfusion independent. Most patients revealed a normal Hb level and a granulocyte count over 1.5 × 10⁹/1 but were still thrombocytopenic due to decreased platelet production. Lymphocytopenia and/or monocytopenia was found in about 30%. Two patients had a monocytosis. Although there was a great range in degree of recovery at various time intervals after ATG. patients tested more than 4 years after ATG tended to have higher cell counts. Lymphocyte counts correlated with the interval between ATG and evaluation, and with haematopoietic recovery. Qualitative abnormalities were found in all cell lines. Most patients showed a homogeneous macrocytic RBC population, and almost 50% a positive sucrose lysis test: only three patients showed evidence of haemolysis and only two of these showed a positive Ham test. Mean platetet volumes were reduced out of proportion to their number. Platelet function, determined by bleeding time and aggregometry, was impaired in over 30%. The granulocytic series showed a shift to the left in about 30%. Hypersegmentation and pseudo Pelger-Huet anomaly were seen in some patients. Lymphocyte subset distribution in blood and bone marrow was within the normal range but absolute blood levels of CD4 cells in particular were slightly decreased, and tended to increase gradually with time after ATG. IgG and IgA levels were significantly decreased. In only one patient cytogenetic analysis of unstimulated bone marrow cells revealed an abnormal karyotype, but in eight of eight patients an increased sensitivity of lymphocytes to X-rays was found. These data suggest impairment at the level of the very early haematopoietic progenitor cell in all patients up to 10 years after ATG. Since similar findings have been reported in clonal (pre-)malignant disease, SAA, improved after ATG treatment, might be prone to clonal (malignant) evolution.     

Treatment of severe aplastic anemia with antithymocyte globulin and cyclosporin A with or without G-CSF in adults: a multicenter randomized study in Japan

We report the results of a randomized study to elucidate whether addition of granulocyte colony-stimulating factor (G-CSF) to immunosuppressive therapy is valuable for the treatment of severe aplastic anemia (SAA) in adults. A total of 101 previously untreated patients (median age, 54 years; range, 19 to 75 years) were randomized to receive antithymocyte globulin (ATG) and cyclosporin A (CyA) (G-CSF- group) or ATG, CyA, and G-CSF (G-CSF+ group). In the G-CSF+ group, the hematologic response rate at 6 months was higher (77% vs 57%; P = .03) than in the G-CSF- group. No differences were observed between the groups in terms of the incidence of infections and febrile episodes. There were no differences between the G-CSF- group and the G-CSF+ group in terms of survival (88% vs 94% at 4 years), and the development of myelodysplastic syndrome (MDS)/acute leukemia (AL) (1 patient vs 2 patients). However, the relapse rate was lower in the G-CSF+ group compared with the G-CSF- group (42% vs 15% at 4 years; P = .01). Further follow-up is required to elucidate the role of G-CSF in immunosuppressive therapy for adult SAA.