Acute graft-versus-host disease (aGVHD) is a major cause of mortality after allogeneic stem cell transplantation. Although initial treatment with corticosteroids is effective in the majority of patients, 30–60% develop steroid resistance. Anti-thymocyte globulin (ATG) is commonly used as first-line therapy for steroid resistant (SR) aGVHD. However, data on its efficacy are limited. At two institutions we reviewed the results of treatment with ATG of 58 patients with SR aGVHD. Initial manifestations of aGVHD were treated with 2 mg/kg/day of methylprednisolone (MP). Equine ATG was administered as first-line therapy for SR aGVHD, a median of 9 days (range, 3 to 39) after initiation of MP. At the time of initiation of ATG, IBMTR severity indices B, C and D were observed in 6%, 40% and 54% of patients, respectively. Improvement was observed in 30% of patients treated with ATG. Skin disease was more likely to improve with ATG (79%), while progression of gut and liver aGVHD was observed in 40% and 66% of patients, respectively. Despite initial improvement, 52 patients (90%) died a median of 40 days after ATG therapy from progressive aGVHD and/or infection (74%), ARDS (15%), or relapse (11%). Only six patients (10%), three of whom had aGVHD limited to the skin at the time ATG was administered, are long-term survivors. We conclude that initial improvement of SR aGVHD occurs with ATG in a minority of patients, and very few patients become long-term survivors. Furthermore, this treatment is associated with a high rate of major complications. Bone Marrow Transplantation (2001) 27, 1059–1064.
Acute graft-versus-host disease (aGVHD) is a significant impediment to successful allogeneic hematopoietic stem cell transplantation. This immunologic event involves activation and clonal expansion of the donor's effector T cells in response to the recipient's disparate histocompatibility antigens, and leads to injury of the target organs: skin, gut, and liver.1 The morbidity and mortality associated with aGVHD correlate with the severity of the organ involvement.2 Despite state-of-the-art prophylaxis, aGVHD occurs in 30–60% of patients after hematopoietic stem cell transplantation from an HLA-identical sibling donor,3,4,5 and the incidence increases with mismatched and unrelated donor transplantation.6,7 Initial treatment for aGVHD routinely consists of intensifying the dose of corticosteroids.8,9 Furthermore, steroid-resistant (SR) aGVHD develops in 30–60% of patients,8,9,10 necessitating secondary intervention.8,9 Anti-thymocyte globulin (ATG) is commonly used as first-line therapy in this setting,8,9 although data on its efficacy are limited.8,9,11
This study reports on 58 patients with SR aGVHD treated with ATG between January 1996 and August 1999 at two institutions: Washington University in St Louis, MO (WU) and City of Hope National Medical Center, Duarte, CA (COH). The purpose of this study was to determine the response of SR aGVHD to ATG and to define the outcomes of these patients.
Material and methods
Transplant recipients who received ATG between January 1996 and August 1999 were identified through a computerized search in the Pharmacy department at both institutions. Records were reviewed and specifically designed case report forms were completed for all patients who were given ATG for SR aGVHD after allogeneic hematopoietic stem cell transplantation. All patients included in this analysis had been followed for a minimum of 1 year or until death.
Diagnosis and staging of aGVHD
Acute GVHD was diagnosed clinically before day 100 and confirmed histologically in skin (67%), gut (61%), or liver (4%). Acute GVHD was staged according to Glucksberg's criteria and an overall grade was assigned according to the IBMTR severity index.2 In two cases, clinical acute GVHD occurred after day +100 as a result of discontinuation of cyclosporin A (CsA) for toxicity reasons.
Definition and treatment of SR aGVHD
SR aGVHD was defined as progressive aGVHD after at least 3 days of MP (2 mg/kg/day) or if unimproving grades III and IV aGVHD (IBMTR severity indices C and D) persisting after at least 7 days of MP (2 mg/kg/day).8 Progression was defined as a change in one organ (skin, gut or liver) leading to an increase by at least one Glucksberg's stage of aGVHD. Unimproving aGVHD was defined as the absence of a difference in any involved organ sufficient to meet minimal criteria for improvement or deterioration. Equine ATG (Atgam, Pharmacia & Upjohn, Peapack, NJ, USA) was initiated as first-line treatment for SR aGVHD.
Response to ATG
Staging and grading of aGVHD was recorded on days 7, 14 and 21 after the first day of ATG. Response was assessed according to previously published criteria.8 Briefly, skin disease was considered to have improved if there was resolution of rash or decrease of involved surface area by ⩾25%. Progressive skin disease was defined as an increase in involved surface area by ⩾25%. Gut disease was considered to have improved if there was resolution of diarrhea, or decrease in the 3-day average stool volume by ⩾500 ml with clearing of cramps and bleeding, if present. Progressive gut disease was defined as an increase in the 3-day average stool volume by ⩾500 ml or new onset of cramps or bleeding. Liver disease was considered to have improved if there was resolution of hyperbilirubinemia or a change in serum bilirubin leading to a decrease by at least one Glucksberg's stage of aGVHD. Progressive liver disease was defined as a change in serum bilirubin leading to an increase by at least one Glucksberg's stage of aGVHD. For all organs, assessment of treatment response was made solely on the basis of clinical criteria. Besides single organ response, an overall response was also determined for every patient.8 Complete response (CR) was defined as resolution of aGVHD in all evaluable involved organs. Partial response (PR) was defined as improvement in at least one evaluable organ without deterioration in the others. Mixed response (MR) was defined as improvement in at least one evaluable organ with deterioration in at least one other. Overall progression was defined as deterioration in at least one evaluable organ without improvement in others, while stable disease was defined as the absence of any difference sufficient to meet minimal criteria for improvement or deterioration in any evaluable organ after treatment.
Results are reported as a proportion. Among patients with infections, the proportion of patients with and without prior exposure to high-dose MP was compared using Fisher's exact test. Similarly, comparison was made of the proportion of patients with invasive fungal infection among those with and without prior exposure to high-dose MP. Survival was estimated using the Kaplan–Meier product limit method. Statistical results were obtained using SAS v.7 (SAS Institute, Cary, NC, USA).
Between January 1996 and August 1999, 307 and 484 patients underwent allogeneic hematopoietic stem cell transplantation at WU and COH, respectively. Fifty-eight (7%) received ATG for SR aGVHD, as defined above. Demographic characteristics of those patients are summarized in Table 1. Thirty-nine received allogeneic bone marrow, and 19 peripheral blood stem cells from an HLA-identical sibling (41%), matched unrelated donor (27%), mismatched sibling (11%) or mismatched unrelated donor (21%). The median age was 36 years (range, 1 to 60). First manifestations of aGVHD were observed between 6 and 123 days post transplant (median 20 days), with skin, gut and liver involvement in 74%, 62% and 36%, respectively. Acute GVHD was initially confined to one organ in 21 patients (42%). All patients were treated with 2 mg/kg/day of MP given as initial therapy between 6 and 126 days post transplant (median 21 days). MP was administered for at least 21 days and doses were subsequently tapered as permitted by clinical response. Additionally, 29 patients (50%) received high-dose MP (20 mg/kg/day for 3 days) prior to initiation of MP at 2 mg/kg/day. CsA was continued during aGVHD treatment unless toxicity was observed.
Treatment with ATG
ATG was initiated for progressive aGVHD in 48 patients (83%) and unimproving grades III–IV aGVHD in 10 patients. Median duration of therapy with MP given at 2 mg/kg/day for aGVHD prior to ATG was 9 days (range, 3 to 39). Only one course of ATG was administered at one of the following dose schedules: 40 mg/kg/day for 4 days (WU adults, n = 34), 15 mg/kg on alternate days for a total of 6 days (WU pediatric, n = 8) or 10–20 mg/kg/day for 5–10 days (COH, n = 16). No patients received a second course of ATG.
Staging of aGVHD on the first day ATG was started is summarized in Table 2. Stages III–IV aGVHD of the skin, gut and liver were observed in 67, 77 and 37%, respectively. Four patients (6%) had an IBMTR severity index B (Glucksberg grade II), 23 (40%) had an IBMTR severity index C (Glucksberg grade III), and 31 patients (54%) had a severity index D (Glucksberg grade IV), with skin, gut and liver involvement in 43, 47 and 30 patients, respectively. Using Glucksberg's grading system, three of the four patients with IBMTR severity index of B had grade III and one patient had grade II (skin and liver) aGVHD. Fifteen patients (26%) had GVHD confined to one organ (seven skin, six gut, one liver) at the time ATG begun.
Response to ATG
Six patients died within 7 days of initiating ATG from unexpected complications (gram-negative sepsis (four), CNS bleed (one), cardio-pulmonary arrest (one), and were therefore not evaluable for response. Table 3 summarizes the individual organ response and overall response to ATG for the 52 evaluable patients. Twenty-one days after initiation of ATG, improvement of aGVHD in the respective organ was seen in 79% of patients with skin, 33% of patients with gut and 14% of patients with liver involvement. Progression was observed in one patient (3%) with skin aGVHD, while progressive aGVHD of the liver and gut were observed in 69% and 40%, respectively. Stable disease in the skin, gut and liver was observed in 18%, 27% and 17%, respectively. Time to initial response in skin, gut and liver aGVHD was 12, 14 and 7 days, respectively. No difference in response was observed among patients treated with the three different ATG schedules (data not shown).
Overall, 31% of patients showed improvement (CR+PR) of aGVHD in all organs involved, 42% had improvement in at least one organ (MR), while stable disease, and progression were observed in 10% and 17% of patients, respectively. Twenty-two patients receive third-line therapy for unsatisfactory response or progression 21 days after ATG was initiated. CsA was changed to FK506 in all 22 patients, hydroxychloroquine was administered to four, and PUVA therapy or extracorporeal phototherapy was initiated in two patients. No significant improvement of aGVHD was observed by the addition of a third agent in those 22 patients.
Complications and outcome
Fifty-two patients (90%) died a median of 40 days after initiation of ATG (range, 2–741) (Figure 1). Causes of death are summarized in Table 4. Infection was observed in 67% of patients (n = 39), and was the major cause of death for 22 patients (38%). Of those infectious episodes, invasive deep fungal infections (Aspergillus, Candida) were suspected (n = 5) or proven (n = 15) in 20 patients (51%). The prevalence of infectious complications did not appear to be affected by prior exposure to high-dose MP. Infections occurred in 19/29 (65.5%) patients previously treated with high-dose MP, compared to 20/29 (59%) patients with no prior exposure to high-dose MP (P = 1.0). Invasive fungal infections accounted for 53% (n = 10) and 50% (n = 10) of those infectious episodes, respectively (P = 1.0). Only six patients (10%), three of whom had aGVHD limited to the skin at the time ATG was initiated, survived 12–60 months post transplant (Figure 1). Characteristics of those six patients were as follows: three were unrelated donor transplant recipients, five were adults, median duration of therapy with MP given at 2 mg/kg/day for aGVHD prior to ATG was 15 days (range, 5–26), ATG was initiated for progressive aGVHD in four of those patients. All six developed extensive chronic GVHD.
This retrospective study performed at two different institutions is the most comprehensive review of the outcomes of SR aGVHD after treatment with equine ATG given as first-line therapy. ATG was administered at three different dose schedules to a cohort of 58 patients with well-defined SR aGVHD: either progressive (83%) or unimproving grades III and IV aGVHD after 2 mg/kg/day of MP. Patients with aGVHD flare during corticosteroid taper were not included. When response was assessed 21 days after initiation of ATG, 31%, of patients showed clinical signs of improvement of aGVHD. Patients with skin involvement were more likely to respond to ATG (79%), whereas liver and gut aGVHD were more often resistant to ATG (improvement in 14% and 33%, respectively). Despite initial improvements of aGVHD with the addition of ATG, complications lead to the demise of the vast majority of patients (90%), with infectious complications being the major contributing cause of death. Only six patients (10%), three of whom had aGVHD limited to the skin at the time of initiation of ATG, are currently alive 12 to 60 months post transplant with extensive chronic GVHD.
Published results of treatment of SR aGVHD with ATG are limited to five studies, four of which are reported in abstract form only. The definition of SR aGVHD was variable in particular with regards to the duration of steroid treatment pre-ATG. The first report by Gluckman et al12 describes nine patients with severe aGVHD treated with equine ATG 15 mg/kg for at least 5 days. Improvement was observed mainly in patients with skin aGVHD, and the overall survival was poor (one patient survived). In a published study from the University of Minnesota, 21 unrelated donor transplant recipients with SR aGVHD received equine ATG 15 mg/kg twice daily for 8–10 doses.13 Improvement of aGVHD was observed in four (19%), and only patients who achieved complete remission of aGVHD survived. At the MD Anderson Cancer Center, 29 patients with SR aGVHD were treated with equine ATG 40 mg/kg/day for 4 days.14 When assessed 28 days after initiation of ATG, improvement of SR aGVHD was observed in 11 patients (41%); however, infection and progressive aGVHD were the major causes of death, which occurred in 86% of patients. A report from Vancouver General Hospital described 32 patients with SR aGVHD treated with rabbit ATG 2.5 mg/kg daily for 4–6 days or on alternate days.15 Improvement of aGVHD was observed in 20 patients (60%). Post-transplant lymphoproliferative disorders were observed in seven patients (22%), and infections developed in 24 (75%). Only one patient ultimately survived. Finally, at the Johns Hopkins Oncology Center, 77 patients were treated with equine ATG for SR aGVHD over a decade.16 Improvement in at least one organ was observed in 60% of patients, with only four (5%) becoming long-term survivors. GVHD and/or infection accounted for 95% of the deaths.
Two other studies have analyzed responses and outcomes of patients who received secondary treatment, including ATG among other interventions, for aGVHD not responsive to primary treatment with corticosteroids.17,18 The University of Minnesota17 reported 61 patients with SR aGVHD of whom nine were treated with equine ATG. Overall, 39% of all patients showed improvement of aGVHD and 37% survived; however, response and outcome of the ATG-treated patients were not specifically detailed. Martin et al18 reported 427 patients of which 79 patients were evaluable for response to treatment with equine ATG. Improvement of aGVHD was observed in 38%. Outcome of patients treated with ATG was not analyzed separately, and the overall non-relapse mortality at 2 years for those patients who achieved CR and PR after second-line therapy for aGVHD was favorable (38% and 61%, respectively). The authors attributed this favorable outcome to the inclusion of patients whose aGVHD resulted from a scheduled taper of corticosteroids, noting that these patients have an inherently better prognosis and that the aGVHD manifestations were rapidly responsive to the reinstitution of corticosteroids. It is noteworthy that no patient developing a flare of aGVHD during corticosteroid taper was included in the present study.
Infections are the leading cause of death in all allogeneic stem cell recipients,19 and the incidence is particularly high in patients with aGVHD.20 The contribution of ATG to this already high risk of fatal infectious complications among patients with aGVHD is unknown. Randomized trials involving ATG as first-line therapy for new-onset aGVHD have failed to demonstrate an increased incidence or severity of opportunistic infections.21 However, it is noteworthy that the median survival of patients with acute leukemia and aGVHD IBMTR severity indices C and D is estimated to be 180 and 75 days, respectively (Rowlings, personal communication). Although far from being statistically comparable, the median survival of our patients in the present study is strikingly shorter.
It has been suggested that early institution of treatment may improve the outcome of aGVHD.22 Therefore, early initiation of ATG in the course of aGVHD might yield better outcomes. A randomized trial from Seattle21 comparing ATG to corticosteroids as initial treatment of aGVHD showed no differences in response rates, infectious complications or survival. Corticosteroids were suggested as the preferred first-line therapy based on a more rapid response and lower toxicity profile. Similarly, in a retrospective review from the University of Minnesota,23 the rate of improvement of aGVHD was comparable for patients who received early treatment (67%) or delayed treatment with ATG after progressing or failing to improve with corticosteroids. No survival advantage at 6 months was observed when primary ATG was compared to secondary ATG. Therefore, in the absence of randomized trials, it seems unlikely that earlier intervention with ATG may prove beneficial in the management of SR aGVHD. Such an approach may expose patients to unnecessary additional immunosuppression thus resulting in a potential increase in the risk of opportunistic infections.
In this retrospective analysis, aGVHD was staged and graded based upon a retrospective review of patient records. Assessment of response of aGVHD to treatment remains complex, and considerable diversity exists among different reviewers in grading aGVHD.24,25 A revised and simplified staging criteria was proposed by the Seattle group to facilitate retrospective grading of aGVHD.25 When these criteria were applied to our patient population, the vast majority of patients (92%) would have been classified as grade IV aGVHD, mainly due to extended hospitalizations before post-transplant day 100 and the observations that aGVHD-related complications represented the leading cause of death.
In summary, this study shows that treatment of SR aGVHD with ATG was associated with initial improvement of signs and symptoms, especially in the skin, but ultimately very few patients became long-term survivors. A high rate of major complications, mainly infectious, was observed after treatment with ATG. Newer approaches for the management of SR aGVHD, as defined in this study, are needed.
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We thank the physicians, nurses and staff at the Washington University (St Louis, MO) and City of Hope (Duarte, CA) who cared for the patients. We especially thank Carla Brewster and Kim Gilfillan for excellent data retrieval. We also thank Dr Philip Rowlings for providing survival estimates from the IBMTR database. We thank Mrs Ruby Morrissey for secretarial support in the preparation of this manuscript. This work was supported by NCI PPG CA 30206 and NCI CA 33572.
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Khoury, H., Kashyap, A., Adkins, D. et al. Treatment of steroid-resistant acute graft-versus-host disease with anti-thymocyte globulin. Bone Marrow Transplant 27, 1059–1064 (2001) doi:10.1038/sj.bmt.1703032
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