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Measurable (‘minimal’) residual disease (MRD) before or after hematopoietic cell transplantation (HCT) identifies adults with AML at risk of poor outcomes. Here, we studied whether peri-transplant MRD dynamics can refine risk assessment. We analyzed 279 adults receiving myeloablative allogeneic HCT in first or second remission who survived at least 35 days and underwent 10-color multiparametric flow cytometry (MFC) analyses of marrow aspirates before and 28±7 days after transplantation. MFC-detectable MRD before (n=63) or after (n=16) transplantation identified patients with high relapse risk and poor survival. Forty-nine patients cleared MRD with HCT conditioning, whereas two patients developed new evidence of disease. The 214 MRDneg/MRDnegpatients had excellent outcomes, whereas both MRDneg/MRDpospatients died within 100 days following transplantation. For patients with pre-HCT MRD, outcomes were poor regardless of post-HCT MRD status, although survival beyond 3 years was only observed among the 58 patients with decreasing but not the seven patients with increasing peri-HCT MRD levels. In multivariable models, pre-HCT but not post-HCT MRD was independently associated with overall survival and risk of relapse. These data indicate that MRDpospatients before transplantation have a high relapse risk regardless of whether or not they clear MFC-detectable disease with conditioning and should be considered for pre-emptive therapeutic strategies.

We carried out bone marrow transplantation (BMT) in 50 patients with myelodysplastic syndrome (MDS) who were 55.3 to 66.2 years of age (median, 58.8 years). According to the criteria of the French-American-British (FAB) classification, 13 patients had refractory anemia (RA), 19 had RA with excess blasts (RAEB), 16 had RAEB in transformation or acute myelogenous leukemia (RAEB-T/AML), and 2 had chronic myelomonocytic leukemia (CMML). According to the recently established International Prognostic Scoring System (IPSS), available for 45 patients, 2 patients were considered low risk; 14, intermediate 1 risk; 19, intermediate 2 risk; and 10, high risk. Conditioning regimens were cyclophosphamide (CY) (120 mg/kg of body weight) plus 12-Gy fractionated total-body irradiation (FTBI) (n = 15), CY plus FTBI with lung and liver shielding (n = 4), busulfan (7 mg/kg) plus FTBI (n = 4), or busulfan (16 mg/kg) plus CY (n = 27). The busulfan-plus-CY group included 16 patients in whom busulfan was targeted to plasma levels of 600 to 900 ng/mL. In these 16 patients, steady-state levels of busulfan actually achieved were 714 to 961 ng/mL (mean ± SD, 845 ± 64 ng/mL; median, 838 ng/mL). The donors were HLA-identical siblings for 34 patients, HLA-nonidentical family members for 4, identical twins for 4, and unrelated volunteers for 6. All 46 patients surviving > 21 days had engraftment, and 22 patients (44%) are surviving 9 to 80 months after BMT. Specifically, among 13 patients with RA, 1 had relapse (cumulative incidence [CI] at 3 years, 8%) and 8 are surviving, for a Kaplan-Meier (KM) estimate of survival at 3 years of 59% (disease-free survival [DSF], 53%). Among 19 patients with RAEB, 3 had relapse (CI at 3 years, 16%), and 8 are surviving disease free (KM estimate at 3 years, 46%). Among 18 patients with RAEB-T/AML or CMML, 6 had relapse (CI at 3 years, 28%), and the KM estimate of DSF at 3 years is 33%. Relapse-free survival had an inverse correlation with cytogenetic risk classification and with the risk score according to the IPSS. Survival in all FAB categories was highest among patients enrolled in a protocol in which busulfan plasma levels were targeted to 600 to 900 ng/mL. These data indicate that BMT can be carried out successfully in patients with MDS who are older than 55 years of age.

We reviewed the records and marrow biopsy specimens of 75 patients with leukemic, myelodysplastic, or myeloproliferative disorders to determine whether the presence of marrow fibrosis affected engraftment after allogeneic marrow transplantation. While 28 control patients without fibrosis achieved prompt engraftment, two of 32 patients (6%) with mild and five of 15 patients (33%) with severe fibrosis failed. The rate of myeloid recovery was significantly slower and the dependence on platelet and red blood cell transfusions was significantly longer in patients with severe fibrosis than in patients with no fibrosis. A finding of severe marrow fibrosis should therefore be taken into account when evaluating the risks and benefits of marrow transplantation.

Patients with acute nonlymphoblastic leukemia (ANL) in first remission (n = 38) or chronic myelocytic leukemia (CML) (n = 55) were given cyclophosphamide and total body irradiation, followed by marrow infusion from HLA-identical siblings. To evaluate postgrafting prophylaxis for acute graft-versus-host disease (GVHD), the patients were randomized to receive either methotrexate and cyclosporine (n = 43) or cyclosporine alone (n = 50). Methotrexate/cyclosporine significantly reduced the incidence and severity of acute GVHD, and improved early survival. This report updates the results with a 3.0 to 4.5 year follow-up. Methotrexate/cyclosporine did not interfere with sustained hematopoietic engraftment, although granulocyte recovery to 1,000/microL was delayed by five days on the average. The incidence of chronic GVHD was identical in the two groups (26% v 24%). Disease-free 3-year survival was slightly better in the methotrexate/cyclosporine group (65% v 54%), but this benefit was restricted to patients with CML (73% v 54%), while no improvement was seen in patients with ANL (41% v 41%). In contrast to patients with CML (relapse rates 8% v 9%), the early survival benefit among patients with ANL given methotrexate/cyclosporine was offset by an increase in leukemic relapses (29% v 16%).

Sixty-five multiply transfused patients with severe aplastic anemia were given cyclophosphamide followed by grafts anemia were given cyclophosphamide followed by grafts from HLA-identical siblings. The effect of the administration of viable donor buffy coat cells following the marrow inoculum was evaluated with regard to graft rejection and survival. Results in 43 patients so treated are presented along with those in 22 concurrent patients given marrow alone. Most patients given buffy coat had positive in vitro tests of sensitization indicating a high risk for graft rejection, while all but one of the patients given marrow alone had negative tests. Thirty of the 43 (70%) patients given marrow and buffy coat are alive between 10 and 61 mo (median 36) after grafting; 4 died after graft rejection and 6 with acute or chronic graft-versus-host disease (GVHD). Eleven of the 22 (50%) patients given marrow alone are alive between 29 and 65 mo (median 52); 7 died after graft rejection and 3 with GVHD. The addition of buffy coat cell infusions to the marrow inoculum reduced the risk of rejection and increased survival in the currently reported transfused patients when compared to patients grafted before 1976. However, there was an increased risk of chronic GVHD. Recipients of marrow from female donors survived slightly better (73%) than recipients of male marrow (58%).

One hundred seventy-nine patients with acute nonlymphoblastic leukemia in first remission (n = 75), chronic myelocytic leukemia in chronic or accelerated phase (n = 48) or leukemia in advanced stage (n = 56) were given HLA-identical marrow grafts and randomized to receive methotrexate or cyclosporine for prevention of graft-v-host disease (GVHD). The current report updates the three prospective trials with follow-ups ranging from 3.2 to 6.2 years after marrow grafting. Results were analyzed separately for each individual study and for all three studies combined. Overall, 40% of patients given cyclosporine and 55% of those given methotrexate developed acute GVHD (P = .13); the incidence of chronic GVHD was 42% and 48%, respectively (P = .67). Twenty-two percent of cyclosporine-treated patients and 30% of methotrexate-treated patients developed interstitial pneumonia of any etiology (P = .25), and the figures for cytomegalovirus pneumonia were 18% and 20%, respectively (P = .41). The overall incidence of leukemic relapse was 31% in cyclosporine-treated patients and 36% in methotrexate-treated patients (P = .75). The probabilities of survival for cyclosporine-v methotrexate-treated patients were comparable for all three study groups: 52% v 48% in patients with acute nonlymphoblastic leukemia (P = .42), 55% v 60% for those with chronic myelocytic leukemia (P = .61), 12% and 12% for those with advanced leukemia (P = .93), and 39% v 38% overall (P = .72). We conclude that cyclosporine and methotrexate are comparable regarding the likelihood of acute/chronic GVHD, interstitial pneumonia, leukemic relapse, and long-term survival.

Four patients with refractory malignant B cell lymphomas were treated with continuous intravenous (IV) infusions of murine monoclonal antibody (MoAb) 1F5 (anti-CD20) over five to ten days. Dose-dependent levels of free serum 1F5 were detected in all patients. Two patients had circulating tumor cells and in both cases 90% of malignant cells were eliminated from the blood stream within four hours of initiation of serotherapy. Antigenic modulation did not occur, and sustained reduction of circulating tumor cells was observed throughout the duration of the infusions. Serial bone marrow aspirations and lymph node biopsies were examined by immunoperoxidase and immunofluorescence techniques to ascertain MoAb penetration into extravascular sites. High doses (100 to 800 mg/m2/d and high serum 1F5 levels (13 to 190 micrograms/mL) were required to coat tumor cells in these compartments in contrast to the low doses that were adequate for depletion of circulating cells. Clinical response appeared to correlate with dose of MoAb administered with progressive disease (52 mg), stable disease (104 mg), minor response (1,032 mg), and partial response (2,380 mg) observed in consecutive patients. The patient treated with the highest 1F5 dose achieved a 90% reduction in evaluable lymph node disease, but the duration of this remission was brief (six weeks). This study demonstrates that high doses of 1F5 can be administered to patients with negligible toxicity by continuous infusion and that clinical responses can be obtained in patients given greater than 1 g of unmodified antibody over a ten-day period.

Forty-six patients with severe aplastic anemia (median age, 23 years) were treated with high-dose cyclophosphamide followed by infusion of marrow from an HLA-identical family member. To evaluate postgrafting prophylaxis for graft-v-host disease (GVHD), they were entered into a prospective randomized trial comparing the effect of a combination of methotrexate and cyclosporine (n = 22) to that of methotrexate alone (n = 24). Forty-four of the forty-six patients had evidence of sustained marrow engraftment. Only one patient in each of the two study groups showed graft rejection. A significant reduction in the cumulative incidence of grades II to IV acute GVHD was seen in patients given methotrexate/cyclosporine (18%) compared with those given methotrexate alone (53%) (P = .012). In three patients given methotrexate alone, grade III developed, and in six, grade IV acute GVHD developed, compared with none given methotrexate/cyclosporine. Eighteen of the 22 patients given methotrexate/cyclosporine and 15 of the 24 given methotrexate alone are alive between 5.5 and 44.5 months (median, 18 months), with actuarial survival rates at 2 years of 82% and 60%, respectively (P = .062). The incidence of fatal infections was higher in patients given methotrexate alone, whereas there are as yet no significant differences in the incidence of chronic GVHD. We conclude that methotrexate/cyclosporine treatment resulted in a significant decrease in the incidence and severity of acute GVHD in patients who received transplants for severe aplastic anemia and thus an improvement in survival.

Eight patients with Fanconi's anemia were given cyclophosphamide alone (seven patients) or combined with procarbazine and antithymocyte globulin (one patient) followed by marrow grafts from HLA-identical siblings. All patients had engraftment. Seven developed acute and three chronic graft-versus-host disease (GVHD). Three patients died with GVHD and infectious complications (days 19, 56, and 82) and one with an intracerebral hemorrhage (day 540). Four patients are surviving 647- 3435 days after grafting, two are well, and two have chronic GVHD that is improving. These results show that Fanconi's anemia can be treated successfully by allogeneic marrow transplantation.

Allogeneic marrow transplantation is curative therapy for thalassemia, but fewer than 30 of patients have an HLA-identical sibling marrow donor. Selection of alternative donors of hematopoietic stem cells (unrelated individuals or HLA-nonidentical family members) has been aided by establishment of world-wide donor registries now exceeding 3.6 million volunteers and by DNA-based HLA typing to more closely match potential donors. Coupled with improved methods to control graft-versus-host disease and prevent fungal and cytomegalovirus infection, remarkable progress has been made in alternative donor transplantation. For patients 50 years of age or younger, with recently diagnosed chronic myelogenous leukemia (CML) in chronic phase, 1- and 5-year survivals after HLA-A, B, DRB1 identical unrelated marrow transplantation in Seattle are 82 and 74, respectively. These results are essentially identical to outcome in similar patients given HLA-matched sibling allografts. However, the world-wide number of alternative donor transplants for thalassemia remains limited to date: 4 unrelated and 60 HLA-nonidentical related transplants have been reported to the IBMTR since 1969 with actuarial overall survival of 75. Using the paradigm of CML, it is likely that access to curative therapy of thalassemia will improve with optimal HLA typing and donor selection early in the course of disease.

Point mutations of the N-ras proto-oncogenes have been previously detected in 20% to 60% of samples of acute myelogenous leukemia (AML), but the clinical significance of these mutations is presently unclear. We directly sequenced polymerase chain reaction (PCR) amplified N-ras fragments to determine the frequency of N-ras point mutations in 55 adult patients with de novo AML. Mutations were present in 8 of 55 (15%) patients. These mutations were usually in codon 12, 13, or 61, but one patient had mutations in both codons 13 and 61, and another had an unusual point mutation in N-ras codon 60. A comparison of patients with and without N-ras mutations showed no statistically significant differences in pretreatment clinical variables, response to induction therapy, or survival, except for a possibly higher percentage of FAB M4 subtypes in patients with the N-ras mutation. These data together with previous reports suggest that the presence of N-ras point mutations do not clearly define a unique clinical or biologic subset of AML patients.

Sixteen patients with leukemia in relapse or second to third remission, 5 to 27 years old (median, 17), were given cyclophosphamide (60 mg/kg X 2) and total body irradiation (2.25 Gy for each of seven days) followed by unmodified marrow grafts from HLA-identical siblings. Patients did not receive posttransplant immunosuppression and were followed a median of nine months (range, 5–17). Prompt engraftment was sustained in 12 patients with a median time of 16 days (range, 10 to 63) to achieve 500 neutrophils/mm3. One patient failed to engraft, one had delayed engraftment, and two had late poor graft function. All 15 with engraftment developed moderate to life-threatening graft-v-host disease (GVHD, eight grade II and seven grade III-IV). This syndrome was hyperacute (median onset eight days [range, 7 to 29] posttransplant) and manifest by severe skin disease (14 patients at stage 3 and one at stage 4), fever (ten patients), and liver (four patients, stage 3–4) or gut (four patients, stage 3–4) involvement. Serial tissue biopsies confirmed acute GVHD in 13 of 15 patients. Ten were treated with antithymocyte globulin and cyclosporine (four survive), and four with corticosteroids (two survive). Actuarial survival to 17 months was 37%. Causes of death included interstitial pneumonia (four), infection (three), graft failure (one), venocclusive disease (one), and relapse of leukemia (one). Age-matched controls receiving standard methotrexate after transplant had comparable relapse-free survival but only a 25% incidence of grade II-IV acute GVHD (P less than .0001). We conclude that deleting posttransplant immunosuppression is associated with frequent and severe hyperacute GVHD, infectious complications, and occasional poor graft function.

Sixteen patients with leukemia in relapse or second to third remission, 5 to 27 years old (median, 17), were given cyclophosphamide (60 mg/kg × 2) and total body irradiation (2.25 Gy for each of seven days) followed by unmodified marrow grafts from HLA-identical siblings. Patients did not receive posttransplant immunosuppression and were followed a median of nine months (range, 5-17). Prompt engraftment was sustained in 12 patients with a median time of 16 days (range, 10 to 63) to achieve 500 neutrophils/ mm3. One patient failed to engraft, one had delayed engraftment, and two had late poor graft function. All 15 with engraftment developed moderate to life-threatening graft-v-host disease (GVHD, eight grade II and seven grade lll-IV). This syndrome was hyperacute (median onset eight dpys [range, 7 to 29] posttransplant) and manifest by severe skin disease (14 patients at stage 3 and one at stage 4), fever (ten patients), and liver (four patients, stage 3-4) or gut (four patients, stage 3-4) involvement, Serial tissue biopsies confirmed acute GVHD in 13 of 15 patients. Ten were treated with antithymocyte globulin end cyclosporins (four survive), and four with corticosteroids (two surviue). Actuarial survival to 17 months was 37%. Causes of death included interstitial pneumonia (four), infection (three), graft failure (one), venocclusive disease (one), and relapse of leukemia (one). Age-matched controls receiving standard methotrexate after transplant had comparable relapse-free survival but only a 25% incidence of grade II-IV acute GVHD (P< .0001). We conclude that deleting posttransplant immunosuppression is associated with frequent and severe hyperacute GVHD, infectious complications, and occasional poor graft function.

We reviewed the records and marrow biopsy specimens of 75 patients with leukemic, myelodysplastic, or myeloproliferative disorders to determine whether the presence of marrow fibrosis affected engraftment after allogeneic marrow transplantation. While 28 control patients without fibrosis achieved prompt engraftment, two of 32 patients (6%) with mild and five of 15 patients (33%) with severe fibrosis failed. The rate of myeloid recovery was signifi- cantly slower and the dependence on platelet and red blood cell transfusions was significantly longer in patients with severe fibrosis than in patients with no fibrosis. A finding of severe marrow fibrosis should therefore be taken into account when evaluating the risks and benefits of marrow transplantation.

Forty-six patients with severe aplastic anemia (median age, 23 years) were treated with high-dose cyclophosphamide followed by infusion of marrow from an HLA-identical family member. To evaluate postgrafting prophylaxis for graft-v-host disease (GVHD), they were entered into a prospective randomized trial comparing the effect of a combination of methotrexate and cyclosporine (n = 22) to that of methotrexate alone (n = 24). Forty-four of the forty-six patients had evidence of sustained marrow engraftment. Only one patient in each of the two study groups showed graft rejection. A significant reduction in the cumulative incidence of grades II to IV acute GVHD was seen in patients given methotrexate/cyclosporine (18%) compared with those given methotrexate alone (53%) (P =. 012). In three patients given methotrexate alone. grade III developed, and in six, grade IV acute GVHD developed, compared with none given methotrexate/ cyclosporine. Eighteen of the 22 patients given methotrex-ate/cyclosporine and 15 of the 24 given methotrexate alone are alive between 5.5 and 44.5 months (median, 18 months), with actuarial survival rates at 2 years of 82% and 60%, respectively (P = .062). The incidence of fatal infections was higher in patients given methotrexate alone, whereas there are as yet no significant differences in the incidence of chronic GVHD. We conclude that methotrexate/cyclosporine treatment resulted in a significant decrease in the incidence and severity of acute GVHD in patients who received transplants for severe aplastic anemia and thus an improvement in survival. © 1986 by Grune & Stratton, Inc.

Canine granulocyte-macrophage colony-stimulating factor (caGM-CSF) was cloned and expressed to allow further investigation of GM-CSF in a large animal model. The cDNA is 850 base pairs (bp) long and encodes a peptide of 144 amino acids. The nucleotide and amino acid sequence homology between caGM-CSF and human GM-CSF (hGM-CSF) is 80% and 70%, respectively. A mammalian expression vector pCMV/CAGM was constructed and used to transfect COS cells for expression of caGM-CSF. Supernatant from transfected COS cells enriched with caGM-CSF was shown to have significant stimulating activity in granulocyte-macrophage colony forming unit (CFU-GM) assays of canine marrow. caGM-CSF, expressed from bacteria, was used to treat seven dogs at varying doses twice daily subcutaneously (sc) for 14 to 16 days. Circulating blood neutrophils and monocytes increased significantly. The increase in circulating eosinophils was variable. Thrombocytopenia developed during administration of caGM-CSF but corrected rapidly after cessation of treatment. Evaluation of survival times of 51Cr-labeled autologous platelets suggested increased consumption as the primary reason for thrombocytopenia. A species-specific GM-CSF will be a useful tool for hematologic or immunologic studies in dogs.

Peripheral blood mononuclear cells (PBMC) were collected after the administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and used as the sole source of hematopoietic stem cells after myeloablative therapy with busulfan (Bu) and cyclophosphamide (Cy). These studies were performed in 12 patients with malignancies (4 non-Hodgkin's lymphoma, 5 breast cancer, 1 testicular carcinoma, 1 Wilm's tumor, and 1 undifferentiated carcinoma) who had bone or bone marrow disease or had low marrow cellularity. rhG-CSF (16 micrograms/kg/d) was administered for 5 to 7 days by subcutaneous injection and PBMC were collected for 2 to 5 days beginning on day 4 after initiation of rhG-CSF, using continuous-flow blood-cell separators that processed 10 to 12 L of whole blood. From a median of three collections, a mean of 24.0 x 10(8) (+/- 10.5 SD) total nucleated cells/kg containing 12.6 x 10(8) (+/- 4.5 SD) mononuclear cells/kg, 7.3 x 10(6) (+/- 4.3 SD) CD34+ cells/kg and 20.5 x 10(4) (+/- 28.1 SD) granulocyte-macrophage colony-forming units (CFU-GM)/kg were harvested and cryopreserved. After the administration of Bu 14 to 17 mg/kg and Cy 120 to 150 mg/kg, PBMC were thawed and infused. One patient received rhG-CSF after the infusion of PBMC and the remaining 11 patients did not receive postinfusion growth factors. Mean days to recovery of neutrophil levels of 0.1, 0.5, and 1.0 x 10(9)/L were 11.4 (range, 9 to 13), 12.7 (range, 10 to 15), and 13.6 (range, 11 to 16) and the mean day to platelet transfusion independence was 13.3 (range, 7 to 49). Time to recovery of neutrophils to 0.5 and 1.0 x 10(9)/L and platelets to 20 x 10(9)/L was more rapid than in historical patients treated with Bu and Cy who received marrow alone or marrow followed by the posttransplant administration of rh-G or GM-CSF. No graft failures have been observed with a follow-up of 4 to 12 months. These results indicate that PBMC collected after rhG-CSF lead to rapid hematopoietic recovery after myeloablative chemotherapy.

A novel immunosuppressant, succinyl acetone (4,6-dioxoheptanoic acid), was studied in dogs. Results with bolus intravenous injections at doses ranging from 50 to 1600 mg/kg showed dose-dependent α and β half-lives, ranging from 30 to 80 min and 7 to 27 hr, respectively. Results suggested that continuous i.v. infusion was necessary to maintain constant plasma levels. Four dogs were given 9.2 Gy total-body irradiation and autologous marrow transplants along with continuous i.v. infusion of succinyl acetone at 50, 100, 200, or 400 mg/kg/day for 21 days, and all four had rapid, sustained hematopoietic engraftment. However, two of the four dogs receiving 200 and 400 mg succinyl acetone/kg/day, respectively, developed bilateral hind-limb ataxia, with histologically confirmed cerebellar lesions in the dog given the higher dose, thus establishing a potential doselimiting neurotoxicity.

Point mutations of the N-ras proto-oncogene have been frequently detected in samples of acute myelogenous leukemia (AML). In general the N-ras point mutation has been found in approximately 25% of samples, with some studies detecting the mutation in as many of 60% of samples. In this report we review the current literature regarding N-ras mutations in AML with emphasis on the updated experience of the Southwest Oncology Group (SWOG). The SWOG study examined 55 adult AML patients prospectively enrolled in a treatment protocol and found N-ras point mutations in 8 of 55 patients (15%). These mutations were usually in codon 12, 13 or 61, but one patient had mutations in both codons 13 and 61, and another had an unusual point mutation in N-ras codon 60. The presence of the N-ras mutation was not associated with pre-treatment clinical variables, response to induction therapy, or survival, except for a higher percentage of FAB M4 subtypes among mutation-positive patients. In this paper we compare the SWOG experience to the aggregate of literature regarding N-ras mutations in AML. In general while the N-ras mutation is common in AML, there is no clear evidence that it is sufficient or necessary for leukemic transformation. The presence of the N-ras mutation in AML does not seem to identify a unique clinical subset of AML patients.

The effects of 9-[2-hydroxy-1-(hydroxymethyl)ethoxymethyl]guanine, or ganciclovir, administered during the immediate posttransplant period to dogs given total-body irradiation and autologous marrow transplants were studied. Doses of ganciclovir of 3.0 mg/kg (body weight) per day were well tolerated without detectable delay in hematopoietic recovery, whereas doses of 5.0 mg/kg per day were associated with delayed platelet recovery.

GvHD is a major cause of morbidity and mortality after allogeneic hemopoietic cell transplantation (HCT). Recent data suggest that rabbit anti-thymocyte globulin (THY) given pre-transplant is effective in reducing the incidence of GvHD. We transplanted 54 patients, 9-65 (median 49) years of age, with advanced myelodysplastic syndrome (MDS, beyond Refractory Anemia[RA], n=29), myelofibrosis (n=12), or other myeloid disorders (n=13), after conditioning with a regimen of targeted busulfan (BU; steady state level 800-900ng/ml), cyclophosphamide (CY) and THY (Thymoglobulin, Sangstat) which was given on days -3,-2 and -1. The starting dose was 4.5 mg/kg (total), to be escalated (in cohorts of 15 patients) to 6.0 and 7.5 mg/kg, dependent upon GvHD incidence and EBV reactivation ≥1000 copies). Patients also received methotrexate (MTX) + cyclosporine (CSP). Seventeen ( patients were accrued in the first cohort (2 did not receive the prescribed dose of THY), and none activated EBV; among 20 patients in the second cohort (5 with incomplete THY dose) one re-activated EBV, and, thus, the third cohort was to receive the same dose, 6 mg/kg, (n=17; two with incomplete THY dose). Donors were HLA-identical siblings in 28, and HLA matched unrelated volunteers in 26 patients. All but two patients had sustained engraftment; 32 (59%) developed acute, and 24 of 46 patients at risk (52%) developed chronic GvHD. The incidence of acute/chronic GvHD was 41%/45% for related, and 60%/36% for unrelated patients given the prescribed doses of THY (80%/85% for the 9 patients in both groups with incomplete THY dose). Relapse incidence for patients given the prescribed dose of THY was 16% for related, and 2% for unrelated recipients; it was 44% among the 9 patients who did not receive the full dose of THY. There was a suggestion that greater ‘area under the curve’ for the CY metabolite CEPM was correlated with non-relapse mortality. Overall, 38 patients (70%) are surviving with a follow-up of 3-20 (median 13) months. Concurrently, 27 patients, 11-64 (median 51) years of age, with low-risk MDS (RA) were conditioned with the identical targeted BUCY regimen (and MTX+CSP) but without THY, and transplanted from HLA-identical related (n=14) or unrelated donors(n=13). All patients engrafted, and none relapsed; 24 (89%) developed acute, and 24 of 25 patients at-risk (96%) developed chronic GvHD. Overall 18 patients (67%) are surviving at 9-39 (median 23) months; there was no difference between related and unrelated transplants. These data suggest that THY, added to targeted BUCY, reduced the incidence of acute and chronic GvHD. With EBV monitoring it may be possible to further escalate the dose of THY and further reduce the incidence of GvHD. However, because of actual or presumed toxicity, 16% of patients did not receive the prescribed dose of THY. There was no evidence for an increase in infections or relapse compared to historical data. The projected survival of patients with advanced disease is encouraging, but longer follow-up is needed.