Reduced-intensity conditioning allogeneic hematopoietic cell transplantation for patients with hematologic malignancies who relapse following autologous transplantation: a multi-institutional prospective study from the Cancer and Leukemia Group B (CALGB trial 100002)

Preferential depletion of host over donor T cells through in vivo decay of active rabbit-anti-thymocyte globulin levels during reduced intensity conditioning

Inadequate T-cell chimerism following reduced-intensity conditioning transplantation may contribute to graft rejection and disease relapse. Anti-thymocyte globulin (ATG) enhances early donor T-cell chimerism, but may also deplete donor T cells, increasing risks of infection and relapse. We prospectively tested administration of rabbit ATG (rATG) ⩾14 days before the infusion of the graft, followed by in vivo decay of active rATG levels, to selectively deplete host T cells. Twenty-three patients received rATG total dose 4.5 mg/kg on days -16 and -15, fludarabine 30 mg/m(2) per day on day -7 through -3, IV busulfan 130 mg/m(2) per day on days -4 and -3 and cyclophosphamide 1500 mg/m(2) on day -2. rATG levels were therapeutic in all patients on day -14, but were sub-therapeutic (<1 μg/mL) by day 0 in 82% of patients. Median donor T-cell chimerisms on days 30 and 180 were 100% (75-100%) and 100% (90-100%), respectively. Non-relapse mortality and relapse/progression at 48 months were 17 and 30%. Cumulative incidences of acute GvHD grades II-IV and III-IV were 39 and 9%. Median follow-up is 64 months (46-79 months). Survival and disease-free survival at 48 months were 70 and 52%. These data suggest that selective depletion of host T cells using this regimen is a feasible and effective strategy.

Comparison of non-myeloablative conditioning regimens for lymphoproliferative disorders

Hematopoietic cell transplantation (HCT) with non-myeloablative conditioning (NMA) for lymphoproliferative diseases (LD) includes fludarabine with and without low-dose total body irradiation (TBI). Transplant outcomes were compared among patients ≥40 years with LD who received a HCT with TBI (N=382) and no-TBI (N=515) NMA from 2001 to 2011. The groups were comparable except for donor, graft, prophylaxis for graft-versus-host disease (GVHD), disease status and year of HCT. Cumulative incidences of grades II–IV GVHD at 100 days, were 29% and 20% (p=0.001), and chronic GVHD at 1 year were 54% and 44% (p=0.004) for TBI and no-TBI, respectively. Multivariate analysis of progression/relapse, treatment failure and mortality showed no outcome differences by conditioning. Full donor chimerism at day 100 was observed in 82% vs. 64% in the TBI and no-TBI groups, respectively (p=0.006). Subset of four most common conditioning/ GVHD prophylaxis combinations demonstrated higher rates of grades II–IV acute (p<0.001) and chronic GVHD (p<0.001) among recipients of TBI-mycophenolate mofetil (MMF) compared to other combinations. TBI-based NMA conditioning induces faster full donor chimerism but overall survival outcomes are comparable to no-TBI regimens. Combination of TBI and MMF are associated with higher rates of GVHD without impact on survival outcomes in patients with LD.

Unrelated donor allogeneic transplantation after failure of autologous transplantation for acute myelogenous leukemia: a study from the center for international blood and marrow transplantation research

The survival of patients with relapsed acute myelogenous leukemia (AML) after autologous hematopoietic stem cell transplantation (auto-HCT) is very poor. We studied the outcomes of 302 patients who underwent secondary allogeneic hematopoietic cell transplantation (allo-HCT) from an unrelated donor (URD) using either myeloablative (n = 242) or reduced-intensity conditioning (RIC; n = 60) regimens reported to the Center for International Blood and Marrow Transplantation Research. After a median follow-up of 58 months (range, 2 to 160 months), the probability of treatment-related mortality was 44% (95% confidence interval [CI], 38%-50%) at 1-year. The 5-year incidence of relapse was 32% (95% CI, 27%-38%), and that of overall survival was 22% (95% CI, 18%-27%). Multivariate analysis revealed a significantly better overal survival with RIC regimens (hazard ratio [HR], 0.51; 95% CI, 0.35-0.75; P <.001), with Karnofsky Performance Status score ≥90% (HR, 0.62; 95% CI, 0.47-0.82: P = .001) and in cytomegalovirus-negative recipients (HR, 0.64; 95% CI, 0.44-0.94; P = .022). A longer interval (>18 months) from auto-HCT to URD allo-HCT was associated with significantly lower riak of relapse (HR, 0.19; 95% CI, 0.09-0.38; P <.001) and improved leukemia-free survival (HR, 0.53; 95% CI, 0.34-0.84; P = .006). URD allo-HCT after auto-HCT relapse resulted in 20% long-term leukemia-free survival, with the best results seen in patients with a longer interval to secondary URD transplantation, with a Karnofsky Performance Status score ≥90%, in complete remission, and using an RIC regimen. Further efforts to reduce treatment-related mortaility and relapse are still needed.

In vivo selection of autologous MGMT gene-modified cells following reduced-intensity conditioning with BCNU and temozolomide in the dog model

Chemotherapy with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) and temozolomide (TMZ) is commonly used for the treatment of glioblastoma multiforme (GBM) and other cancers. In preparation for a clinical gene therapy study in patients with glioblastoma, we wished to study whether these reagents could be used as a reduced-intensity conditioning regimen for autologous transplantation of gene-modified cells. We used an MGMT(P140K)-expressing lentivirus vector to modify dog CD34(+) cells and tested in four dogs whether these autologous cells engraft and provide chemoprotection after transplantation. Treatment with O(6)-benzylguanine (O6BG)/TMZ after transplantation resulted in gene marking levels up to 75%, without significant hematopoietic cytopenia, which is consistent with hematopoietic chemoprotection. Retrovirus integration analysis showed that multiple clones contribute to hematopoiesis. These studies demonstrate the ability to achieve stable engraftment of MGMT(P140K)-modified autologous hematopoietic stem cells (HSCs) after a novel reduced-intensity conditioning protocol using a combination of BCNU and TMZ. Furthermore, we show that MGMT(P140K)-HSC engraftment provides chemoprotection during TMZ dose escalation. Clinically, chemoconditioning with BCNU and TMZ should facilitate engraftment of MGMT(P140K)-modified cells while providing antitumor activity for patients with poor prognosis glioblastoma or alkylating agent-sensitive tumors, thereby supporting dose-intensified chemotherapy regimens.

Clinical options after failure of allogeneic hematopoietic stem cell transplantation in patients with hematologic malignancies

Disease recurrence is the single most common cause of death after allogeneic or autologous hematopoietic stem cell transplantation (HSCT). Disease status and chemosensitivity at the time of transplantation, as well as the development of graft-versus-host disease (GVHD), are factors known to influence the risk of relapse post-HSCT. Both acute and chronic GVHD have been associated with decreased relapse rates; however, owing to toxicity, overall survival is not consistently improved in these patients. Furthermore, there is a transient period of immunodeficiency after HSCT, which may permit residual malignant cells to proliferate early in the post-transplant course, before the donor immune system can establish a graft-versus-tumor response. Patients who fail an initial HSCT have an extremely poor outcome; therefore, maneuvers to prevent, identify and treat recurrent disease as early as possible in these situations are necessary. Strategies to distinguish graft-versus-tumor from GVHD, to enhance both general and disease-specific immune reconstitution after transplantation, and to increase donor-mediated anti-host immune reactions are being investigated in clinical trials. Single agent nontoxic post-HSCT chemotherapy, cellular therapies and second allogeneic HSCT using reduced intensity regimens are among the modalities under investigation.

Current status of allogeneic transplantation for aggressive non-Hodgkin lymphoma

PURPOSE OF REVIEW

To provide a succinct update on the role of allogeneic stem cell transplantation (allo-SCT) in the management of patients with aggressive lymphomas. To clarify the indications for allogeneic transplantation vis-à-vis autologous transplant and to discuss the rationale and potential benefits of reduced intensity conditioning (RIC), nonmyeloablative (NMA) transplant, T-cell depletion and variations in graft vs. host disease (GVHD) prophylaxis.

RECENT FINDINGS

Considerable effort has been spent in developing transplant regimens with reduced toxicity and reduced GVHD. The role of allogeneic transplantation has also been redefined in light of advances in lymphoma classification, diagnostic methods, particularly PET scan and advances in transplant technology. Haplo and umbilical cord blood SCT allow identification of a donor for nearly all patients.

SUMMARY

In diffuse large B-cell lymphoma, the outcome of allo-SCT depends on patient characteristics and chemosensitivity. It is useful after failure of auto-SCT and in partial responses to salvage therapy. Allo-SCT may be the treatment of choice for advanced T-cell and natural killer cell lymphoma and for adult T-cell leukemia-lymphoma. Prophylactic or preemptive donor lymphocyte infusion may be useful, but requires controlled studies. RIC and NMA conditioning have reduced early toxicity but are associated with increased risk for disease recurrence. Promising data have been reported from a novel conditioning regimen combining NMA with ibritumomab tiuxetan. T-cell depletion reduces chronic GVHD but has some increase in rate of recurrence. Rapamycin may be associated with reduction in risk for disease recurrence.