Clonal remission in aplastic anemia after treatment with antithymocyte globulin.

Aplastic anemia includes a group of disorders characterized by peripheral blood pancytopenia and marrow hypocellularity. The current report describes a patient who is an apparent constitutional mosaic and presented with marrow aplasia. Using cytogenetic analysis of bone marrow, skin, and peripheral T lymphocytes, we demonstrated the clonal nature of this patient's aplastic marrow, and, in addition, identify clonal evolution. The patient was treated with antithymocyte globulin (ATG) and achieved a complete remission, with disappearance of an abnormal evolved clone. This case illustrates that clonal cytogenetic abnormalities do not preclude a response to ATG and that aplastic anemia may be a nonmalignant clonal disorder with clonal evolution.     

In vivo effects of horse and rabbit antithymocyte globulin in patients with severe aplastic anemia

We recently reported that rabbit antithymocyte globulin was markedly inferior to horse antithymocyte globulin as a primary treatment for severe aplastic anemia. Here we expand on our findings in this unique cohort of patients. Rabbit antithymocyte globulin was detectable in plasma for longer periods than horse antithymocyte globulin; rabbit antithymocyte globulin in plasma retained functional capacity to bind to lymphocytes for up to 1 month, horse antithymocyte globulin for only about 2 weeks. In the first week after treatment there were much lower numbers of neutrophils in patients treated with rabbit antithymocyte globulin than in patients receiving horse antithymocyte globulin. Both antithymocyte globulins induced a “cytokine storm” in the first 2 days after administration. Compared with horse antithymocyte globulin, rabbit antithymocyte globulin was associated with higher levels of chemokine (C-C motif) ligand 4 during the first 3 weeks. Besides a much lower absolute number and a lower relative frequency of CD4⁺ T cells, rabbit antithymocyte globulin induced higher frequencies of CD4⁺CD38⁺, CD3⁺CD4⁻CD8⁻ T cells, and B cells than did horse antithymocyte globulin. Serum sickness occurred around 2 weeks after infusion of both types of antithymocyte globulin. Human anti-antithymocyte globulin antibodies, especially of the IgM subtype, correlated with serum sickness, which appeared concurrently with clearance of antithymocyte globulin in blood and with the production of cytokines. In conclusion, rabbit and horse antithymocyte globulins have very different pharmacokinetics and effects on neutrophils, lymphocyte subsets, and cytokine release. These differences may be related to their efficacy in suppressing the immune system and restoring hematopoiesis in bone marrow failure. Clinicaltrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT00260689","term_id":"NCT00260689"}}NCT00260689.     

Refractory aplastic anemia: concomitant therapy with antithymocyte globulin and high-dose corticosteroids

Bone marrow transplantation is possible for only a minority of patients with severe aplastic anemia. There has been successful treatment in some patients with immunosuppressive agents: high-dose 6-methylprednisolone, antilymphocyte globulin, and antithymocyte globulin. We report the successful treatment of two patients with severe aplastic anemia with the simultaneous administration of antithymocyte globulin and high-dose 6-methylprednisolone after failure with antithymocyte globulin and low-dose corticosteroids.     

In vitro production of granulocyte-macrophage colony-stimulating factor in aplastic anemia: possible mechanisms of action of antithymocyte globulin

Various abnormalities of lymphokine production have been described in patients with aplastic anemia. To determine if abnormal production of hematopoietic growth factors could contribute to the process of aplastic anemia we studied the in vitro production of human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) by phytohemagglutinin (PHA)- and antithymocyte globulin (ATG)-stimulated peripheral blood lymphocytes from 29 patients with aplastic anemia and 15 normal controls. GM-CSF production in response to 1% PHA was seen in nearly all samples (43 of 44) and similar amounts of GM-CSF were produced by patients with aplastic anemia and normal controls. Production of GM-CSF by ATG-stimulated lymphocytes was seen in 7 of 23 patients with aplastic anemia (30%); two of these patients also demonstrated low-level spontaneous production of GM-CSF. Production of GM-CSF in response to ATG was also seen in 2 of 11 normal controls (18%) and barely detectable spontaneous production of GM-CSF was seen in both. Biologically active IL-3 could also be detected in PHA- or ATG-stimulated peripheral blood mononuclear cells in several patients and normal controls. Our results indicate that lymphocytes from patients with aplastic anemia can be stimulated in vitro to produce normal quantities of GM-CSF, suggesting that impaired potential for production of T-cell derived hematopoietic growth factors is unlikely to account for the marrow hypoplasia seen. In several patients overproduction of GM-CSF was observed, consistent with the notion that some patients with aplastic anemia may have circulating activated T cells. We also demonstrate that ATG can stimulate the production of growth factors such as IL-3 and GM-CSF, supporting the role for ATG in stimulating hematopoiesis.     

Rapid progression of fibrosing alveolitis and thyrotoxicosis after antithymocyte globulin therapy for aplastic anemia

Antithymocyte globulin (ATG) therapy is an established form of treatment for aplastic anaemia and has also been used as prophylaxis against graft rejection of bone marrow and renal allografts. Administration of ATG preparations has been associated with many mild clinical reactions, as have other forms of immunomodulatory therapy. However, serious adverse effects appear to be rare. We report a case of rapidly progressive fibrosing alveolitis and thyrotoxicosis in relation to ATG therapy, highlighting its potential toxicity and emphasising that its administration should be undertaken by experienced physicians in specialised centres.     

Long-term follow up after allogeneic stem cell transplantation in patients with severe aplastic anemia after cyclophosphamide plus antithymocyte globulin conditioning

Background

Due to increased rates of secondary solid organ cancer in patients with severe aplastic anemia who received an irradiation-based conditioning regimen, we decided some years ago to use the combination of cyclophosphamide and antithymocyte globulin. We report the long-term follow up of patients who underwent hematopoietic stem cell transplantation from an HLA-matched sibling donor after this conditioning regimen.

Design and Methods

We analyzed 61 consecutive patients transplanted from June 1991 to February 2010, following conditioning with cyclophosphamide (200 mg/kg) and antithymocyte globulin (2.5 mg/kg/day × 5 days).

Results

Median age was 21 years (range 4–43); 41 of the 61 patients were adults. Median duration of the disease before hematopoietic stem cell transplantation was 93 days. All but 2 patients received bone marrow as the source of stem cells and all but 2 engrafted. Cumulative incidence of acute grade II–IV graft-versus-host disease was 23% (95%CI 13–34) and 18 developed chronic graft-versus-host disease (cumulative incidence 32% at 72 months, 95% CI 20–46). In multivariate analysis, a higher number of infused CD3 cells was associated with an increased risk of developing chronic graft-versus-host disease (P=0.017). With a median follow up of 73 months (range 8–233), the estimated 6-year overall survival was 87% (95% CI 78–97). At 72 months, the cumulative incidence of avascular necrosis was 21% and 12 patients presented with endocrine dysfunction (cumulative incidence of 19%). Only one patient developed a secondary malignancy (Hodgkin’s lymphoma) during follow up.

Conclusions

Cyclophosphamide and antithymocyte globulin is an effective conditioning regimen for patients with severe aplastic anemia and is associated with low treatment-related mortality. Long-term complications include avascular necrosis and endocrine dysfunction.     

Long-term follow-up of allogeneic stem cell transplantation in patients with severe aplastic anemia after conditioning with cyclophosphamide plus antithymocyte globulin

We investigated the efficacy of an antithymocyte globulin/cyclophosphamide preparative regimen prior to allogeneic stem cell transplantation from HLA-identical siblings in patients with severe aplastic anemia. Since 1990, 21 patients, 6 males and 15 females, with a median age of 25 years (range: 7-43) have been enrolled in the protocol consisting of 200 mg/kg cyclophosphamide and 90-120 mg/kg antithymocyte globulin (ATG, rabbit, Fresenius, Bad Homburg, Germany). For further graft-versus-host disease (GVHD) prophylaxis all patients received cyclosporin A and a short course of methotrexate (MTX). Only one patient had a primary graft failure (5%). All other patients engrafted with a leukocyte count >1.0 x 10(9)/l and a platelet count >20 x 10(9)/l after a median of 19 (range: 11-28) and 26 days (range: 13-67), respectively. No late graft failure or relapse was observed. Two patients experienced mild acute GVHD grade I (10%), and one patient developed grade II GVHD (5%). No severe grade III/IV GVHD was observed; 17% of the patients developed limited chronic GVHD. The treatment-related mortality was 14% and mainly due to fungal infection. After a median follow-up of 70 months (range: 2-139), the estimated overall and event-free survival at 10 years for all patients is 86% (95% confidence interval: 70-100%). We conclude that ATG plus cyclophosphamide is an effective conditioning regimen in patients with aplastic anemia undergoing stem cell transplantation with a low treatment-related mortality, resulting in an excellent outcome.     

Long-term outcome after immunosuppressive therapy with horse or rabbit antithymocyte globulin and cyclosporine for severe aplastic anemia in children

Some prospective studies showed that rabbit antithymocyte globulin was inferior to horse antithymocyte globulin as first-line therapy for patients with severe aplastic anemia. We retrospectively analyzed the clinical outcome of 455 children with severe aplastic anemia who received horse antithymocyte globulin (n=297) or rabbit antithymocyte globulin (n=158) combined with cyclosporine as first-line therapy between 1992 and 2010. The response rates were comparable between the horse and rabbit antithymocyte globulin groups at 3 months [46% (136/294) versus 42% (66/153), P=0.55] and 6 months [60% (178/292) versus 55% (87/143), P=1.0]. Using multivariate analysis, differences in antithymocyte globulin preparations were not associated with response rates. However, 2-year and 10-year overall survival rates in the horse antithymocyte globulin group were significantly better than those in the rabbit antithymocyte globulin group (2-year overall survival: 96% versus 87%, 10-year overall survival: 92% versus 84%, P=0.004). On the basis of multivariate analysis, use of rabbit antithymocyte globulin was a significant adverse factor for overall survival (hazard ratio = 3.56, 95% confidence interval, 1.53 – 8.28, P=0.003). Rabbit antithymocyte globulin caused more profound immunosuppression, which might be responsible for the higher incidence of severe infections. Considering that there are no studies showing the superiority of rabbit antithymocyte globulin over horse antithymocyte globulin, horse antithymocyte globulin should be recommended as a first-line therapy. However, our results justify the use of rabbit antithymocyte globulin as first-line therapy if horse antithymocyte globulin is not available.     

重型再生障碍性贫血细胞免疫功能异常与强化免疫抑制治疗的关系

重型再生障碍性贫血（SAA）患者骨髓造血功能衰竭的发生、发展与细胞免疫紊乱,特别是T细胞数量、功能的 异常密切相关,因此免疫功能异常在SAA的发病机制中起着重要的作用。目前抗胸腺细胞球蛋白（ATG）或抗淋巴细 胞球蛋白（ALG）联合环胞霉素A（CsA）的强化免疫抑制治疗（IST）对改善SAA 预后有显著疗效。IST 能够使 60％～80％的SAA患者得到血液学恢复即是异常免疫反应损伤造血干细胞的最直接证据。然而,由其他非免疫因 素介导或造血干细胞极度耗竭所致的骨髓衰竭,IST就可能无效。因此,在IST前进行疾病评估和疗效预测具有重要 意义,其中细胞免疫功能异常对初治SAA进行IST的疗效具有重要意义。     

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.     

Immunosuppressive therapy using antithymocyte globulin, cyclosporine, and danazol with or without human granulocyte colony-stimulating factor in children with acquired aplastic anemia

A prospective multicenter trial of 119 children 1 to 18 years of age with newly diagnosed aplastic anemia (AA) was conducted, comparing treatment using antithymocyte globulin (ATG), cyclosporine (CyA), and danazol (DAN) with or without rhG-CSF (400 microg/m(2), day on days 1-90). All children with very severe AA received rhG-CSF (VSAA group, n = 50). The other children were randomized to receive ATG, CyA, DAN, and rhG-CSF (G-CSF+ group, n = 35) or ATG, CyA, and DAN without rhG-CSF (G-CSF- group, n = 34). After 6 months, the hematologic response rate was 71%, 55%, and 77% in the VSAA group, G-CSF+ group, and G-CSF- group, respectively. There was no difference in the incidence of febrile episodes and documented infections between the G-CSF+ and G-CSF- groups. Bone marrow transplantation (BMT) was attempted in 22 patients in whom initial immunosuppressive therapy (IST; n = 18) failed or in whom a relapse occurred after an initial response (n = 4). Nineteen of the 22 patients are alive and well after a median follow-up of 18 months (range, 3 to 66 months) since BMT. The probability of survival at 4 years was 83% +/- 7% in the VSAA group, 91% +/- 5% in the G-CSF+ group, and 93% +/- 6% in the G-CSF- group. Myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) developed in one patient in each of the three groups; the overall risk for MDS/AML was 3% +/- 2% at 4 years. Because the results of IST were encouraging, it is suggested that children with AA receive IST as first-line therapy if there is no human leukocyte antigen-matched sibling donor.     

In vitro response of T cells from aplastic anemia patients to antilymphocyte globulin and phytohemagglutinin: colony-stimulating activity and lymphokine production

The aim of the present study was to compare the response of bone marrow (BM) lymphocytes from patients with aplastic anemia (AA) or normal controls to increasing doses of antilymphocyte globulin (ALG) or phytohemagglutinin (PHA). For this purpose BM T-enriched cells from 11 AA patients and 9 normal individuals were incubated with ALG (0-1000 micrograms/ml) or PHA (0%-10%) for 1 day, and the supernatants were tested for suppression/enhancement of granulocyte-macrophage colony-forming unit (CFU-GM) growth and for release of granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) assayed with the enzyme-amplified sensitivity immunoassay (EASI). The production of colony-stimulating activity (CSA) by T cells primed with ALG and tested in the absence of exogenous GM-CSF correlated with the dose of ALG in priming cultures up to 14% EG (100% EG = CFU-GM growth with 30 ng/ml of GM-CSF). The amount of GM-CSF in the supernatants paralleled their capacity to sustain CFU-GM growth (up to 3.5 ng/ml of GM-CSF). Production of CSA or GM-CSF from T cells primed with PHA was significantly lower. Supernatants of PHA-primed T cells, when added to normal BM cells in the presence of exogenous GM-CSF, produced a dose-dependent inhibition of CFU-GM growth (down to 13% +/- 10% EG). The same supernatants contained detectable amounts of IFN-gamma and TNF-alpha (21 +/- 6.7 IU/ml and 4.6 +/- 2.9 ng/ml, respectively). IFN-gamma production from severe AA (SAA) T cells in response to PHA was significantly superior to the IFN-gamma production from normal T cells (21 +/- 6.7 IU/ml vs 9.5 +/- 7.1 IU/ml, p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

重型再生障碍性贫血患者树突细胞刺激异体淋巴细胞增殖的功能

目的 了解重型再生障碍性贫血(SAA)患者树突细胞(DC)刺激异体淋巴细胞增殖的功能,探讨SAA的免疫病理机制.方法 以25例SAA患者和12例正常对照者为研究对象,以重组人白介素-4(rhIL-4)、重组人粒-巨噬细胞集落刺激因子(rhGM-CSF)和重组人肿瘤坏死因子(rhTNF)体外诱导骨髓单核细胞分化为成熟髓细胞样DC(mDC),与正常淋巴细胞按1:100、1:50作混合淋巴细胞培养(MLR),噻唑兰(MTT)比色法计算淋巴细胞增殖率.ELISA法检测MLR培养上清IL-12、干扰素γ(IFNγ)浓度.分析MLR上清液IL-4、IFNγ水平与淋巴细胞增殖率相关性.结果 SAA初治组、恢复组和对照组mDC与淋巴细胞1:100混合培养时,淋巴细胞增殖率分别为(219.8 ±94.0)%、(159.1 ±66.0)%、(160.1 ±91.9)%,培养上清IL-12水平分别为(8.2±3.6)ng/L、(6.5±2.8)ng/L、(6.1±2.6)ng/L,IFNγ,水平分别为(21.8 ±8.7)ng/L、(25.5±9.1)ng/L和(22.6±7.8)ng/L3组差异均无统计学意义(P值均>0.05).初治组、恢复组和对照组mDC与淋巴细胞1:50混合培养时,淋巴细胞增殖率分别为(322.1±171.1)%、(180.9±79.1)%、(192.3 ±91.9)%,培养上清IL-12水平分别为(12.6 ±4.4)ng/L、(9.4 ±3.3)ng/L、(8.5 ±3.7)ng/L,IFNγ,水平分别为(32.3 ±9.2)ng/L、(27.4 ±6.5)ng/L、(24.4 ±7.4)ng/L,3项指标初治组均高于对照组(P<0.05),恢复组与对照组比较差异无统计学意义(P>0.05).MLR上清液IL-12水平与淋巴细胞增殖率呈正相关(r=0.529,P<0.01);MLR上清液IFNγ水平与淋巴细胞增殖率旱正相关(r=0.381,P<0.05).结论 SAA患者mDC刺激淋巴细胞增殖功能增强,在SAA发病中起重要作用.     

Unrelated bone marrow transplantation in two severe aplastic anemia patients preconditioned with a regimen of cyclophosphamide, antithymocyte globulin, and total body irradiation

We report our experiences with HLA-matched unrelated bonemarrow transplantation combining a preconditioning regimen of cyclophosphamide, antithymocyte globulin (ATG), and total body irradiation for two patients with severe aplastic anemia (SAA) who had already undergone repeated blood transfusions. Short-term methotrexate and cyclosporine were administered for graft-versus-host disease (GVHD) prophylaxis. Both patients achieved rapid engraftment within 3 weeks, furthermore, neither acute nor chronic GVHD developed. Our conditioning regimen appeared to be well-suited for unrelated bone marrow transplantation in heavily transfused SAA patients. However, both patients experienced bouts of fever about 20-30 and 40-50 days after transplantation, and it was difficult to differentiate whether they were affected by acute GVHD, cytomegalovirus (CMV) infections, or serum sickness. Because weakly positive CMV antigenemia was detected, both patients were given ganciclovir. Although their fever did not respond initially, it gradually subsided following the combined administration of prednisolone. These outcomes suggest it is essential that attention be devoted to the potential for serum sickness and the high risk of herpes virus infections, particularly by CMV, following the use of intensive preconditioning regimens that include ATG.     

Analysis of lymphocyte subsets in patients with aplastic anemia before and during immunosuppressive therapy

Summary To define the contribution of T-lymphocyte subsets in the development of aplastic anemia (AA), T-cell subpopulations including T cells, T cells, and TCS1-positive T cells, were analyzed by cytophotometry in the peripheral blood (PB) and bone marrow (BM) of patients with AA before and after 6 weeks of therapy with anti-lymphocyte globulin (ALG), methylprednisolone, and cyclosporin A (CSA). In nine patients with AA a significant decrease of PB- and BM-derived T cells was observed after 6 weeks of therapy as compared with normal controls. At diagnosis, the CD4/CD8 ratio in PB and BM of the patients did not differ from the ratio in the control population; however, a reversed ratio (< 1) was present in PB as well as in BM after weeks of therapy. Interestingly, lymphocytes expressing the T-cell receptor (TCR) were significantly decreased both before (PB 1.2±0.1%; BM 0.8±0.1%) and after 6 weeks of therapy (PB 0.7±0.1%; BM 0.7±0.1%) as compared with healthy controls (PB 2.4±0.2%; BM 2.3±0.2%). However, the proportion of the -T-cell subpopulation expressing the TCS1 phenotype was markedly increased before (PB 42±3.5%; BM 31±3%) and especially after 42 days of therapy (PB 77±12%; BM 45±2%) as compared with that in normal subjects (PB 19±2%; BM 9.7±0.8%). At present, follow-up is under evaluation to correlate these findings with hematological response. The pathophysiological significance of the observed alterations within the T-cell subsets and especially the T-cell populations will require further functional analyses, in particular since TCS1-positive T cells exhibit autoimmunological capacity.Presented at the annual meeting of the German Society for Hematology and Oncology, 4–7 October 1992, Berlin     

Remission induction in a patient with severe aplastic anemia and renal failure by immunosuppressive treatment including antithymocyte globulin

Summary The pathogenesis of severe aplastic anemia (SAA) is still unclear. Based on clinical and experimental data the hypothesis has been put forward that autoimmune mechanisms may be involved. Encouraging results have been presented with various immunosuppressive drugs including antithymocyte globulin (ATG). We report the successful treatment of SAA with bolus methylprednisolone and ATG in a patient with high-grade renal failure. ATG was tolerated without side effects.     

Fludarabine, cyclophosphamide and horse antithymocyte globulin conditioning regimen for allogeneic peripheral blood stem cell transplantation performed in non-HEPA filter rooms for multiply transfused patients with severe aplastic anemia

Multiply transfused patients of severe aplastic anemia are at increased risk of graft rejection. Five such patients underwent peripheral blood stem cell transplantation from HLA-identical siblings with a fludarabine-based protocol. The conditioning consisted of fludarabine 30 mg/m(2)/day x 6 days, cyclophosphamide 60 mg/kg/day x 2 days and horse antithymocyte globulin (ATG) x 4 days. Two different ATG preparations were used: ATGAM (dose 30 mg/kg/day x 4 days) or Thymogam (dose 40 mg/kg/day x 4 days). Engraftment: median time to absolute neutrophil count (ANC) >0.5 x 10(9)/l was 11 days (range: 8-17) and median time to platelet count >20 x 10(9)/l was 11 days (range: 9-17). At a median follow-up of 171 days (range: 47-389), there has been no graft rejection and all patients are in complete remission. Acute GVHD (grade 1) occurred in one patient only. Chronic GVHD developed in two patients (extensive in one and limited in another). The transplants were performed in non-HEPA filter rooms. In only one patient, systemic antifungal therapy (voriconazole) was used. The use of Thymogam brand of ATG for conditioning is being reported for the first time. Our experience suggests that this fludarabine-based protocol allows rapid sustained engraftment in high-risk patients without significant immediate toxicity.     

Second marrow transplants in patients with aplastic anemia rejecting the first graft: use of a conditioning regimen including cyclophosphamide and antithymocyte globulin

Sixteen (11%) of 146 consecutive patients with severe aplastic anemia prepared for engraftment with cyclophosphamide (200 mg/kg) rejected marrow grafts from their HLA-identical siblings. They were given a second marrow transplant from either the same (n = 13) or a second (n = 3) HLA-identical sibling between 23 and 743 (median 86) days after the first transplant. The preparation for the second transplant included cyclophosphamide, 50 mg/kg, on each of four successive days. Twelve hours after each of the first three doses of cyclophosphamide, antithymocyte globulin, 30 mg/kg/dose, was infused. One of the 16 patients died from infection too early after the second transplant to be evaluated, two had failure of engraftment and died with infection, one rejected the second graft and is surviving almost 5 years later with full autologous marrow recovery, and 12 had successful and sustained second grafts. Of these 12, six are surviving between 11 months and 7 3/4 years. Four of the six have no graft-v-host disease (GVHD), while two have chronic GVHD requiring treatment. Five have Karnofsky scores of 100% and one of 90%. Six of the 12 patients with sustained grafts died between 63 days and 38 months after transplantation, four with infections (related in two patients to chronic GVHD), one with acute GVHD, and one with hemorrhage. The average interval from first to second transplant was 308 days during the past five years, compared to 61 days in earlier patients. Five of seven recent patients are surviving, compared to two of nine earlier patients. In conclusion, successful second transplants after cyclophosphamide and antithymocyte globulin are possible in most patients with aplastic anemia who have rejected their first marrow grafts; however, mortality remains high, with only 40% of the patients becoming long-term survivors.