Long-term outcome of unrelated donor transplantation for AML using myeloablative conditioning incorporating pretransplant Alemtuzumab

Impact of in vivo T-cell depletion on outcome of AML patients in first CR given peripheral blood stem cells and reduced-intensity conditioning allo-SCT from a HLA-identical sibling donor: a report from the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation

The impact of in vivo T-cell depletion on transplantation outcomes in patients transplanted with reduced-intensity conditioning (RIC) remains controversial. This study assessed the outcome of 1250 adult patients with de novo AML in first CR (CR1) given PBSC from HLA-identical siblings after chemotherapy-based RIC. A total of 554 patients did not receive any form of in vivo T-cell depletion (control group), whereas antithymocyte globulin (ATG) and alemtuzumab were given in 444 and 252 patients, respectively. The incidences of grade II-IV acute GVHD were 21.4, 17.6 and 10.2% in control, ATG and alemtuzumab patients, respectively (P<0.001). In multivariate analysis, the use of ATG and the use of alemtuzumab were each associated with a lower risk of chronic GVHD (P<0.001 each), but a similar risk of relapse, and of nonrelapse mortality, and similar leukemia-free survival and OS. Further, among patients given BU-based RIC, the use of <6 mg/kg ATG did not increase the risk of relapse (hazard ratio, HR=1.1), whereas there was a suggestion for higher relapse risk in patients given 6 mg/kg ATG (HR=1.4, P=0.08). In summary, these data suggest that a certain amount of in vivo T-cell depletion can be safely used in the conditioning of AML patients in CR1 given PBSC after chemotherapy-based RIC.

Pilot study of prophylactic ex vivo costimulated donor leukocyte infusion after reduced-intensity conditioned allogeneic stem cell transplantation

Donor leukocyte infusion (DLI) can induce potent graft-versus-leukemia (GVL) activity in patients with relapsed hematologic malignancies after allogeneic hematopoietic stem cell transplantation (HSCT). Unfortunately, except in patients with chronic-phase chronic myelogenous leukemia, responses to DLI have been disappointing. GVL induction is likely to be most effective in the setting of minimal residual disease. Prevention of relapse through the provision of prophylactic DLI to high-risk patients may improve the outcome of allogeneic HSCT. We previously reported that ex vivo costimulated T cell infusion of activated DLI (aDLI) as treatment for relapse is safe and has potent GVL effects. We hypothesized that prophylactic aDLI can be given safely and prevent relapse in high-risk patients after allogeneic HSCT. Eighteen patients with acute myeolgenous leukemia (n = 14), acute lymphoblastic leukemia (n = 3), or myelodysplastic syndrome (n = 1) underwent allogeneic HSCT after a reduced-intensity conditioning (RIC) regimen with alemtuzumab, fludarabine, and busulfan. Graft-versus-host-disease (GVHD) prophylaxis consisted of tacrolimus and methotrexate with a planned early and rapid taper of tacrolimus. Patients without GVHD, off immune suppression, and in remission received aDLI at a dose of 1 × 10(7) CD3(+) cells/kg (aDLI 1) at day +120, followed by a second infusion of 1 × 10(8) CD3 cells/kg (aDLI 2) at day +180. At a median follow-up of 58 months, 5 of the 18 patients (28%) were alive, and 4 patients were in remission. Eleven patients (65%) relapsed, at a median time of 191 days. Twelve of the 18 patients received at least one aDLI, and 6 of these 12 patients also received aDLI 2. Six patients did not receive any aDLI owing to early relapse (n = 2), protocol ineligibility (n = 1), or GVHD (n = 3). Only 2 of the 12 patients who received aDLI 1 developed GVHD. Two out of the 12 patients remain in remission at the time of this report. Disease recurrence was the cause of death in 10 of the 13 patients (77%) who died. Our data indicate that prophylactic ex vivo costimulated CD3/CD28 DLI is safe, feasible, and not associated with significant GVHD. Relapse remains the major cause of treatment failure after RIC HSCT even with rapid withdrawal of immune suppression and the use of prophylactic aDLI, and better strategies to prevent relapse are needed.

Pharmacological methods to reduce disease recurrence

Allogeneic stem cell transplantation is an increasingly important treatment option in patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Although there has been substantial progress in reducing transplantation-related mortality (TRM), little progress has been made in reducing the risk of disease relapse, which continues to represent the major cause of treatment failure in patients allografted for AML and MDS. Experience with myeloablative conditioning regimens has demonstrated that, although intensification of the preparative regimen reduces relapse risk, any survival benefit is blunted by a concomitant increase in TRM. A similar inverse correlation between relapse risk and TRM is observed in patients allografted using a reduced-intensity conditioning regimen. However, the markedly lower toxicity of such regimens has permitted the design of novel conditioning strategies aimed at maximizing antitumor activity without excessive transplant toxicity. Coupled with recent advances in drug delivery and design, this has allowed the development of a spectrum of new conditioning regimens in patients with high-risk AML and MDS. At the same time, the optimization of a graft-versus-leukemia (GVL) effect by minimizing posttransplantation immunosuppression, with or without the infusion of donor lymphocytes, is essential if the risk of disease relapse is to be reduced. Recently, the delivery of adjunctive posttransplantation therapies has emerged as a promising method of augmenting antileukemic activity, either through a direct antitumor activity or consequent upon pharmacological manipulation of the alloreactive response. Taken together these advances present a realistic possibility of delivering improved outcome in patients allografted for high-risk AML or MDS.

Comparative outcomes of donor graft CD34+ selection and immune suppressive therapy as graft-versus-host disease prophylaxis for patients with acute myeloid leukemia in complete remission undergoing HLA-matched sibling allogeneic hematopoietic cell transplantation

PURPOSE

T-cell depletion (TCD) reduces the incidence of graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT). However, concerns about relapse, graft rejection, and variability in technique have limited the widespread application of this approach.

PATIENTS AND METHODS

Outcomes of 44 patients receiving HLA-identical sibling TCD grafts using a uniform technique for CD34(+) selection as the sole form of immune suppression were compared with outcomes of 84 patients receiving T-replete grafts and pharmacologic immune suppression therapy (IST).

RESULTS

Groups were similar, except for fewer men (36% with TCD v 56% with IST) and more frequent use of radiation-containing regimens (100% with TCD v 50% with IST) in the CD34-selected TCD cohort. The proportion of patients with neutrophil engraftment at day 28 was similar (96% with IST and 100% with TCD grafts). The 100-day rates of grade 2 to 4 acute GVHD were 39% and 23% with IST and TCD grafts, respectively (P = .07). Corresponding 2-year rates of chronic GVHD were lower with TCD grafts than IST (19% v 50%, respectively; P < .001). There were no differences in rates of graft rejection, leukemia relapse, treatment-related mortality, and disease-free and overall survival rates. At 1 year, 54% and 12% of patients were still on immunosuppression in the IST and TCD cohorts, respectively. TCD was associated with a higher GVHD-free survival at 2 years compared with IST (41% v 19%, respectively; P = .006).

CONCLUSION

These results suggest that TCD via CD34 selection might lower long-term morbidity as a result of chronic GVHD without negatively impacting relapse rates in patients with acute myeloid leukemia. Additional prospective studies should be undertaken to definitively address the role of TCD in HCT.

Pretransplant conditioning with Campath-1H (alemtuzumab) in pediatric matched unrelated hematopoietic stem cell transplants: an institutional experience

Graft versus host disease (GVHD) remains a major cause of mortality and morbidity after matched unrelated hematopoietic stem cell transplantation (HSCT). Campath-1 H (alemtuzumab), a humanized monoclonal antibody to CD52 antigen, is thought to reduce GVHD incidence through in vivo T-cell depletion. Through the same mechanism it can potentially increase the risk of relapse by reducing the graft versus leukemia effect and possibly increase the risk of infection due to delayed immune recovery. A retrospective case analysis of 17 pediatric matched unrelated HSCTs done in our institution between January 2003 and June 2009 with Campath-1H as part of the pretransplant conditioning regimen was conducted. Grade I-II acute GVHD was noted in 29.4% of the HSCTs. No patient developed chronic GVHD. All but one patient with severe aplastic anemia engrafted. A relapse of primary disease was noted in 35.3% of the transplants. Three patient deaths were due to relapse and 1 due to disseminated varicella infection. Overall survival was 100% and 94% at 100 days and 1 year, respectively. Our experience suggests Campath-1H used as part of pretransplant conditioning regimen in pediatric unrelated HSCTs effectively reduces the risk of serious GVHD with no apparent increase in life-threatening infections or relapse compared with that reported with conventional regimens. Larger studies, with longer duration of follow-up, are required to further assess its role with regards to graft versus leukemia effect and to establish if the decreased incidence of GVHD and infectious complications is sustained in larger cohorts.

Pharmacokinetics and clinical activity of very low-dose alemtuzumab in transplantation for acute leukemia

The optimal dose of in vivo-administrated alemtuzumab in the allogeneic transplantation setting has not been defined. We report our experience on 37 patients with high-risk diseases, mainly acute leukemia (AML 23, ALL 10 patients), who underwent sibling (49%) or unrelated (51%) PBSCT (35 patients), and received a total dose of only 10-20 mg Campath-1H as part of the conditioning, and post-transplant CYA without MTX. The neutrophil and especially the platelet engraftment were rapid. There were only two grade III-IV acute GvHD cases, which occurred in unrelated transplants in the Campath-10 cohort. Chronic GvHD developed in six cases (17%) and was limited to skin in five of them. After a median follow-up of 371 days (59-1191), 70% patients are alive and in CR (Karnofsky 100%), and 11 died (TRM n=6, relapse n=5). From the five patients relapsed, three were at advanced stage at transplant and four underwent sibling HCT with the higher (20 mg) alemtuzumab dose. With the 10 mg alemtuzumab schedule (5 mg/day at days -2 and -1) we achieve at day of transplantation low but still lymphotoxic alemtuzumab serum concentrations (176 ng/mL), whereas levels declined fast thereafter, and at engraftment nearly no Campath antibody remained in the patient's serum.

Low-dose total body irradiation and fludarabine conditioning for HLA class I-mismatched donor stem cell transplantation and immunologic recovery in patients with hematologic malignancies: a multicenter trial

HLA-mismatched grafts are a viable alternative source for patients without HLA-matched donors receiving ablative hematopoietic cell transplantation (HCT), although their use in reduced intensity conditioning (RIC) or nonmyeloablative (NMA) conditioning HCT has been not well established. Here, we extended HCT to recipients of HLA class I-mismatched grafts to investigate whether NMA conditioning can establish stable donor engraftment. Fifty-nine patients were conditioned with fludarabine (Flu) 90 mg/m(2) and 2 Gy total body irradiation (TBI), followed by immunosuppression with cyclosporine (CsA) 5.0 mg/kg twice a day and mycophenolate mofetil (MMF) 15 mg/kg 3 times a day for transplantation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSCs) from related (n = 5) or unrelated donors (n = 54) with 1 antigen +/- 1 allele HLA class I mismatch or 2 HLA class I allele mismatches. Sustained donor engraftment was observed in 95% of the evaluable patients. The incidence of grade II-IV acute and extensive chronic graft-versus-host disease (aGVHD, cGVHD) was 69% and 41%, respectively. The cumulative probability of nonrelapse mortality (NRM) was 47% at 2 years. Two-year overall and progression-free survival (OS, PFS) was 29% and 28%, respectively. NMA conditioning with Flu and low-dose TBI, followed by HCT using HLA class I-mismatched donors leads to successful engraftment and long-term survival; however, the high incidence of aGVHD and NRM needs to be addressed by alternate GVHD prophylaxis regimens.

TBI with lung dose reduction does not improve hematopoietic cell homing to BM during allogeneic transplantation

Purpose

To determine the effects of total body irradiation (TBI) dose, fractionation, and lung shielding on hematopoietic stem cell homing to the bone marrow.

Material and Methods

Bone marrow (BM) cells were extracted from tibiae and femurs of B6-GFP mice and were transplanted into B6 mice. Recipient mice had either: 1) no radiation, 2) single dose TBI at 13.6 Gray (Gy), 3) single dose TBI at 13.6 Gy with reduced lung exposure to 0.4 Gy by shielding, 4) split dose TBI at 12 Gy to twice/day over four days, or 5) split dose TBI at 12 Gy to twice/day over four days with reduced lung exposure to 0.36 Gy by shielding. The last radiation exposure preceded tail vein injection by 4–6 hours. Mice were sacrificed after 18 hours.

Results

Homing of GFP positive, lineage negative cells was not significantly improved in any irradiated group compared to control. Homing of GFP positive, lineage negative, Kit positive cells was significantly worse in all irradiated groups.

Conclusion

TBI does not improve the homing of lineage negative donor BM cells to the recipient marrow. Homing of lineage negative, Kit positive donor BM cells was significantly worse following TBI, with or without lung dose reduction.

Comparable outcome of alternative donor and matched sibling donor hematopoietic stem cell transplant for children with acute lymphoblastic leukemia in first or second remission using alemtuzumab in a myeloablative conditioning regimen

HLA-matched sibling donor (MSD) stem cell transplantation can cure>60% of pediatric patients with acute lymphoblastic leukemia (ALL), but <30% of patients will have a sibling donor. Alternative donor (AD) transplantation can be curative but has a higher risk of graft-versus-host disease (GVHD). The addition of alemtuzumab (Campath 1-H) to AD transplants produces in vivo T cell depletion, which may reduce the risk for GVHD. We now report the outcome for 83 children with ALL (41 MSD, 42 AD) undergoing stem cell transplantation in first or second complete remission. All patients received myeloablative conditioning, including cyclophosphamide, cytarabine arabinoside, and total-body irradiation, with alemtuzumab administered to AD recipients. GVHD prophylaxis consisted of a calcineurin inhibitor with either short-course methotrexate or prednisone. Disease-free survival (DFS) for MSD recipients was 72.3% (95% confidence interval [CI], 55.4%-83.6%) versus 62.4% (95% CI, 45.2%-75.4%) for AD recipients. The 100-day mortality was 7.1% in the AD group and 2.4% in the MSD group. Relapse rates were identical (24%). Treatment-related mortality, principally viral infection, explained the difference in survival. For children undergoing stem cell transplantation (SCT) from alternative donors, alemtuzumab with a myeloablative conditioning regimen resulted in DFS comparable to MSD.