Intensive immunosuppression with antithymocyte globulin and cyclosporine as treatment for severe acquired aplastic anemia

Immunosuppressive therapy can produce hematologic improvement in a large proportion of patients with severe aplastic anemia. Antithymocyte globulin (ATG) is the current treatment of choice for patients who do not have histocompatible sibling donors or who are otherwise inegligible for allogeneic bone marrow transplantation. About 50% of patients respond to an initial course of ATG, and many nonresponders can be salvaged by subsequent treatment with cyclosporine (CsA). To determine whether simultaneous administration of these agents could further improve response rates, we enrolled 55 patients in a therapeutic trial of 4 days of ATG and 6 months of CsA. Among the 51 patients who had not received previous courses of ATG or CsA, 67% had responded by 3 months, and 78% had responded by 1 year (response was defined as an increase in peripheral blood counts sufficient that a patient no longer met the criteria for severe disease). There was a high incidence of relapse (36% actuarial risk at 2 years), but most relapsed patients responded to additional courses of immunosuppression, and relapse was not associated with a significant survival disadvantage. Evolution to myelodysplastic syndromes and acute leukemia was rare (1 of 51 patients), but the later appearance of paroxysmal nocturnal hemoglobinuria was more common (5 of 51 patients). Actuarial survival was 86% at 1 year and 72% at 2 years. These data support the use of a combination immunosuppressive regimen containing both ATG and CsA as first-line therapy for severe aplastic anemia.     

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.     

Prolonged cyclosporine administration after antithymocyte globulin delays but does not prevent relapse in severe aplastic anemia

In severe aplastic anemia, approximately one‐third of responders to standard horse antithymocyte globulin (h‐ATG) plus cyclosporine (CsA) will relapse. Anecdotal experience has suggested that a gradual CsA taper might avoid relapse, but this practice has not been rigorously assessed prospectively. In 2003, we adopted a strategy to taper CsA beyond 6 months, with the intention to reduce hematologic relapse compared with our extensive historical experience. In total, 102 patients received h‐ATG/CsA for 6 months in two sequential clinical protocols: 67 patients (66%) responded and all had the CsA dose tapered per protocol over the subsequent 18 months (total of 2 years). The rate of relapse at 5 years was 33% (95% CI 27–44%), which did not differ from our large historical relapse experience (patients treated before 2003) of 30–40%, in protocols in which CsA was simply discontinued at 6 months. However, time to relapse was prolonged by about 1 year with the longer CsA course. The rates of clonal evolution and overall survival did not differ between the two cohorts. We infer from this large prospective study that CsA taper as implemented delayed but did not prevent relapse. The kinetics of relapse with long course CsA does suggest that a lower long‐term dose might be adequate to maintain patients in remission. Am. J. Hematol. 89:571–574, 2014. © Published 2014.     

Cyclosporin A for the treatment of aplastic anemia refractory to antithymocyte globulin

Antithymocyte globulin (ATG) is an established form of therapy for severe aplastic anemia (SAA). However, in patients who do not respond to this treatment and who are not candidates for bone marrow transplantation few successful therapeutic alternatives exist. We report two such patients who have shown a therapeutic response to Cyclosporin A (CSA) (Sandimmune, Sandoz). Case 1, a 15 year old male, and Case 2, a 34 year old female, were diagnosed as having SAA in September 1984 and May 1984 respectively. Treatment with high dose Methylprednisolone (MPN) and ATG in Case 1 and MPN, ATG and Oxymetholone in Case 2 for ten days was ineffective in both cases. Case 1 developed anaphylaxis with both repeat ATG and ALG (antilymphoblast globulin), and Case 2 failed to respond to repeat ATG. Both required frequent packed cells and platelet transfusions. At five and six months respectively following completion of ATG therapy, CSA was started at 10 mg/kg/day in divided doses orally. Renal and liver functions and CSA blood levels were followed. Within six weeks both patients exhibited a hematologic response and were no longer transfusion dependent. On maintenance therapy of 4 mg/kg/day (Case 1) and four months after discontinuing CSA (Case 2) the hematologic values are as follows: hemoglobin 160 and 130 g/L, absolute granulocyte count 3100 and 1640 × 10⁹/L, and platelets 132 and 84 × 10⁹/L respectively. Side effects included hypertrichosis, gingival hyperplasia and mild reversible nephrotoxicity. CSA appears to represent an effective form of therapy for patients with SAA refractory to ATG.     

Antithymocyte globulin and cyclosporine for treatment of 44 children with hepatitis associated aplastic anemia

We analyzed the outcomes of 44 children with hepatitis associated aplastic anemia (HAA) who received immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and cyclosporine (CsA). Fourteen (31.8%) patients achieved complete response and 17 (38.6%) achieved partial response, for an overall response rate of 70.4% after 6 months. Seven non-responders received bone marrow transplantation from an HLA-matched unrelated donor and 6 out of 7 are alive. The probability of overall survival at 10 years was 88.3+/-4.9%, which supports the role of IST with ATG and CsA as treatment of choice for children with HAA without an HLA identical sibling donor.     

The status of antithymocyte globulin therapy for adult patients in Japan: retrospective analysis of a nationwide survey

We conducted a nationwide survey on antithymocyte globulin (ATG) therapy for adult patients in Japan. We mailed questionnaires to 454 hospitals with hematology divisions, of which 181 (40%) responded, and the records of 448 patients were collected. Patient characteristics, hematological responses, and adverse effects were evaluated in 421 patients with sufficient data. A total of 366 patients had idiopathic aplastic anemia (AA), 29 had other types of AA, and 25 had other diseases. The response rate (RR) at 6 months was 54% for all patients, and 53% for those with idiopathic AA. Ten patients (2%) died within 30 days, and 11 (3%) died between 31 and 100 days after ATG therapy. In 346 patients with moderate to very severe AA, who received their first ATG therapy, factors that influence the outcomes of ATG therapy were extracted. Among 11 pre-treatment and therapy-related variables, three were found to be correlated with a higher RR: shorter duration of AA, no history of specific therapy for AA, and the use of CsA. Most notably, the RR of patients treated within 3 months of diagnosis, those between 3 months and 2 years, and those later than 2 years were 68% (130/190), 48% (54/113), and 13% (5/38), respectively.     

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.     

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.     

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.     

Treatment of aplastic anemia with antithymocyte globulin, high-dose corticosteroids, and androgens

A total of 46 patients with aplastic anemia (34 severe; 12 moderate) were treated with antihuman thymocyte globulin (ATG), high-dose methylprednisolone, and oxymetholone. Early symptoms of ATG toxicity included fever, rash, and bronchospasm. Signs of serum sickness also developed in 23 patients. Complications associated with high doses of steroids were hyperglycemia, hypertension, fluid retention, gastrointestinal hemorrhage, and aseptic necrosis of the hip. Other morbidity possible associated with steroid administration included seizures, arrhythmias, and headache with papilledema. Studies of elevated liver function necessitated discontinuation of androgen therapy in eight patients. A complete or partial hematological response was noted in 19 patients (41%). Of these, three have had recurrent cytopenias, of whom one has developed a myelodysplastic syndrome. There are currently 34 patients surviving, and 12 who have died. Actuarial survival at three years is 65%. These response and survival data are comparable to those of previous trials using ATG and androgens without high-dose steroids. A prospective, randomized trial is needed to determine whether the addition of high-dose corticosteroids to ATG does significantly increase the rate and frequency of response in order to justify the toxicity of this additional immunosuppressive therapy in the treatment of aplastic anemia.     

Lymphokine abnormalities in aplastic anemia: implications for the mechanism of action of antithymocyte globulin

Anti-thymocyte globulin (ATG) provides effective therapy for many patients with aplastic anemia, and its mechanism of action has been presumed to be secondary to lymphocytotoxicity. However, our studies of lymphocyte function in aplastic anemia show marked abnormalities of lymphokine production, which ATG may modulate. In 12 of 17 patients with aplastic anemia, interleukin 2 (IL2) production was markedly elevated in vitro (P less than .01 by paired statistical analysis). Expression of the IL2 receptor, or Tac antigen, on peripheral lymphocytes assessed by flow microfluorometry was also increased above the normal range in 11 of 15 cases. Studies of ATG suggested that it might act to stimulate lymphocyte function. In vitro, ATG is a mitogen, as measured by incorporation of 3H-thymidine into blood mononuclear cells; the response of cells to ATG from patients with aplastic anemia was exaggerated in comparison with normals. Cell proliferation was accompanied by production of IL2 to levels that were, in some cases, similar to those obtained with lectin stimulation. Finally, supernatants from lymphocytes cultured in the presence of ATG were able to replace adherent cells in providing growth factors for the support of nonadherent cells in methylcellulose hematopoietic colony assays. These results provide a mechanism for an "immunostimulatory" action of ATG in effecting hematopoietic response in some patients with aplastic anemia.     

Cyclophosphamide combined with antithymocyte globulin in preparation for allogeneic marrow transplants in patients with aplastic anemia

Graft rejection has been a problem after marrow grafts for patients with aplastic anemia who were conditioned with cyclophosphamide (CY). Rejection lessened when patients were given the marrow donor's peripheral blood buffy-coat cells in addition to the marrow, but this result was achieved at the price of more chronic graft-versus-host disease (GVHD). Results with second transplants suggested that CY alternating with antithymocyte globulin (ATG) was more immunosuppressive than CY alone. Therefore, the current study explored CY and ATG without buffy-coat cell transfusions in 39 patients with aplastic anemia given marrow transplants from HLA-identical family members (siblings in 38 cases, father in 1 case). We hoped both to minimize the risks of graft rejection and of chronic GVHD and to improve survival. Patients were 2 to 52 years of age (median, 24.5); 87% had received previous transfusions, and 41% had therapy with immunosuppressive agents before transplant. They were administered four daily doses of CY (total, 200 mg/kg) alternating with three doses of ATG (total, 90 mg/kg) followed by an HLA-identical marrow graft. Methotrexate and cyclosporine were administered to prevent GVHD. Two patients rejected their grafts (5%), and both were successfully retransplanted. Acute (grade 2 or 3) GVHD occurred in 15% and chronic GVHD in 34% of patients. The actuarial survival rate at 3 years was 92%, which compares favorably to the 72% survival rate in 39 historical patients who were matched with current patients for age and risk factors for rejection and GVHD. CY/ATG is a well-tolerated and effective conditioning program for marrow grafting in aplastic anemia that, when combined with GVHD prevention by methotrexate/cyclosporine, results in excellent survival.     

A multicenter trial of antithymocyte globulin in aplastic anemia and related diseases

One hundred fifty patients with bone marrow failure were treated in three groups with antithymocyte globulin (ATG; Upjohn, Kalamazoo, MI) in a multicenter trial. Patients were assessed at 3, 6, and 12 months after initiation of treatment by three criteria: transfusion independence, clinical improvement, and blood counts. Group I consisted of 77 patients with acute severe aplastic anemia, randomized to receive either ten or 28 days of ATG. There was no significant difference between the two arms of this protocol: 47% of all patients were clinically improved and 31% were transfusion independent at 3 months. Of the severely affected patients, 27% died before 3 months; most deaths occurred early in treatment. Factors associated with survival in severely affected patients included male sex, age less than 40 years, absolute neutrophil count greater than 200/microL, and idiopathic etiology. Neutrophil counts generally increased by 8 weeks after treatment, but patients continued to show improvement to 1 year posttreatment. In Group II, 44 patients with moderate or chronic severe aplastic anemia were randomized to receive either ten days of ATG or 3 months of high-dose nandrolone decanoate. No patient initially treated with androgens recovered, but 28% of ATG-treated cases achieved transfusion independence at 3 months. Group III consisted of patients with a variety of bone marrow failure syndromes. Patients with pancytopenia and cellular bone marrow showed response rates similar to those of patients with chronic or moderate aplastic anemia.     

Clinical analysis of predictive factors for the response to antithymocyte globulin in patients with aplastic anemia

We report the results of a retrospective study of antithymocyte globulin (ATG) treatment in 17 adult patients with aplastic anemia (AA). We evaluated 24 ATG treatments which included re-treatment with ATG in patients who had not responded to the first ATG treatment or who had relapsed after the first remission. The median age was 66 years, and the median follow-up period was 52 months. The response and relapse rates of ATG treatment were 70.8% and 23.1%, respectively. The response rate of ATG re-treatment was 57.1%. Overall survival and event-free survival at 10 years were 66.7% and 50.7%, respectively. The shorter duration from diagnosis to ATG treatment, the higher reticulocyte count before ATG treatment, and being female independently correlated with the efficacy of ATG treatment. Two patients developed monosomy 7 clonal abnormality. These results suggest that ATG treatment can achieve a high response rate and long-term survival among patients with adult AA. However, we have to pay attention to the development of the clonal diseases.     

Do androgens enhance the response to antithymocyte globulin in patients with aplastic anemia? A prospective randomized trial

We analyzed the effect of antithymocyte globulin (ATG) with or without androgens in 121 patients with aplastic anemia. Fifty-three patients with moderate to severe aplastic anemia were prospectively randomized to receive ATG with or without oral androgens. Eleven of 26 patients (42%) receiving ATG plus androgen responded, including three complete and eight partial responses. Twelve of 27 patients (44%) receiving ATG plus placebo responded, including five complete and seven partial responses. The difference in response rates was not significant (P greater than .9). Survival was also comparable in the two groups; for patients with severe aplastic anemia, actuarial survival at two years was 55% +/- 24% (95% confidence interval) in patients receiving ATG plus androgen compared with 50% +/- 24% in the ATG plus placebo group (P = .65). Furthermore, results in both groups were indistinguishable from those obtained in 68 historical controls receiving ATG without androgens. These data indicate that androgens are not required in order to respond to antithymocyte globulin and the addition of androgens, as used in this trial, did not significantly improve response rates to ATG treatment.     

Rapid and complete reconstitution of autologous haemopoiesis after cord blood infusion in treatment‐naive patients with severe aplastic anemia receiving high‐dose cyclophosphamide/ATG therapy

Although high‐dose cyclophosphamide seems to achieve durable complete remission, there are still concerns about its too much early toxicity. So, we designed a clinical study to investigate the effects of high‐dose cyclophosphamide/ATG combined with cord blood infusion as first‐line therapy for patients with severe aplastic anemia. Patients and Method: Between January 2003 and September 2007, we treated 16 treatment‐naive patients with severe aplastic anemia with cord blood infusion after high‐dose cyclophosphamide (50 mg/kg/d × 2) and rabbit antithymocyte globulin (3 mg/kg/d × 5) therapy. Results: Although only one patient had durable full donor engraftment, 14 of the enrolled 16 patients had rapid autologous hematopoietic recovery. The median recovery time for neutrophils and platelets was only 23 and 37 d after infusion of cord blood. Of the 15 responding patients, all patients achieved treatment‐free remission: nine patients met the criteria for a complete remission; six patients achieved a partial remission. Conclusion: Infusion of cord blood after high‐dose cyclophosphamide/ATG resulted in a rapid autologous hematologic recovery and a high response rate in patients with treatment‐naive patients with severe aplastic anemia. These promising results merit further investigation and confirmation on a larger number of patients.     

Differentiation of normal marrow and HL60 cells induced by antithymocyte globulin.

Antithymocyte globulin (ATG) therapy is an important treatment alternative for patients with acquired aplastic anemia. The mechanism by which it exerts its effects on hematopoiesis is unknown. In this report, we describe the ability of horse ATG to induce growth and differentiation of normal bone marrow. A single cell suspension of normal human bone marrow was cultured in methylcellulose medium and examined for the growth and maturation after incubation with ATG (10 micrograms/ml). After 3-4 days of culture, spherical colonies containing mature myeloid elements were found in cultures containing ATG but not in cultures containing medium or preimmunization horse IgG. The addition of 10% colony-stimulating factor increased growth by 40%. The number of spherical colonies is not dependent on the presence of macrophages or T lymphocytes. This property of ATG may be relevant to the mechanism behind the hematologic recovery in some patients with acquired aplastic anemia. We also describe the ability of ATG to induce terminal differentiation in the HL60 leukemic cell line. ATG binds to HL60 cells and at concentrations between 10 and 100 micrograms/ml, 50% of the cells become mature granulocytes, acquire the ability to reduce nitroblue tetrazolium, and lose their proliferative capacity in the clonogenic assay. These new observations of ATG-induced differentiation of normal marrow myeloid elements and terminal differentiation of the HL60 cell line point to different avenues for future search of differentiation-inducing agents.     

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 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.     

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.