Hematopoietic cell transplantation in older patients with hematologic malignancies: replacing high-dose cytotoxic therapy with graft-versus-tumor effects

Phenotype, function and chimaerism of monocyte-derived blood dendritic cells after allogeneic haematopoietic stem cell transplantation

Dendritic cells (DCs) are essential for initiating T-cell responses against either host- or leukaemia-specific antigens. We analysed phenotype, allostimulatory capacity and chimaerism of monocyte-derived DCs (moDCs) serially in 28 patients receiving allogeneic stem cell grafts after conventional myeloablative (n = 14) or reduced-intensity conditioning (RIC, n = 14). Although the recovery of phenotype and function of moDCs after myeloablative stem cell transplantation (SCT) was prompt, there was a trend to a lower expression of co-stimulatory molecules and major histocompatibility antigen class II antigens on mature moDCs in patients who had received RIC transplants. Similarly, the allostimulatory capacity of mature moDCs after RIC transplants was reduced for up to 6 months. Six out of 14 (43%) RIC transplant patients showed a pattern of mixed chimaerism within the first 3 months after transplant. RIC transplant patients with a mixed donor DC chimaerism had a significantly higher risk of relapse (75% versus 35% for patients with full donor DC chimaerism, P = 0.03) but a lower incidence of acute graft-versus-host disease (25% versus 56% for patients with full donor DC chimaerism, P = 0.157). These data, although preliminary, provide evidence that DC function is impaired after RIC transplants and that DC chimaerism may have an impact on graft-versus-host and graft-versus-leukaemia reactions.

HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative conditioning for patients with hematologic malignancies

A hematopoietic cell transplantation (HCT) approach was developed for elderly or ill patients with hematologic malignancies that employed nonmyeloablative conditioning to avoid common regimen-related toxicities and relied on graft-versus-tumor effects for control of malignancy. Eighty-nine patients, median age 53 years, were given fludarabine (90 mg/m2) and 2 Gy total body irradiation. Marrow (n = 18) or granulocyte colony-stimulating factor (G-CSF)-stimulated peripheral blood mononuclear cells (G-PBMCs; n = 71) were transplanted from unrelated donors matched for human leukocyte antigen A (HLA-A), -B, -C antigens and -DRB1 and -DQB1 alleles. Postgrafting immunosuppression included mycophenolate mofetil and cyclosporine. Donor T-cell chimerism was higher for G-PBMCs compared with marrow recipients. Durable engraftment was observed in 85% of G-PBMCs and 56% of marrow recipients. Cumulative probabilities of grade II, III, and IV acute graft-versus-host disease (GVHD) were 42%, 8%, and 2%, respectively. Nonrelapse mortality at day 100 and at 1 year was 11% and 16%, respectively. One-year overall survivals and progression-free survivals were 52% and 38%, respectively. G-PBMC recipients had improved survival (57% vs 33%) and progression-free survival (44% vs 17%) compared with marrow recipients. HLA-matched unrelated donor HCT after nonmyeloablative conditioning is feasible in patients ineligible for conventional HCT. G-PBMCs conferred higher donor T-cell chimerism, greater durable engraftment, and better progression-free and overall survivals compared with marrow.

Lymphodepleting effects and safety of pentostatin for nonmyeloablative allogeneic stem-cell transplantation1

Nonmyeloablative allogeneic stem-cell transplantation (alloNST) is the focus of investigations searching for less-toxic transplantation regimens. We report studies on the kinetics of lymphodepletion and safety of pentostatin (PT) conditioning in alloNST. Patients with hematologic malignancy received mobilized blood from human leukocyte antigen-matched related (n=4) or unrelated (n=8) donors. PT 4 mg/m2 was administered on days -21, -20, and -19 and 200 cGy of total-body irradiation was administered on day -1, followed by cyclosporine A and mycophenolate mofetil. Mononuclear cell adenosine deaminase after PT was inhibited 84%. The absolute CD3+ cells decreased significantly by day -7 (49%) and CD19+ cells declined 92% by day -1. CD4+ cells were depressed more than CD8+ cells. Neutrophils and monocytes were minimally affected by PT. Median posttransplant peripheral blood chimerism on day 70 showed 95% donor leukocytes and 82.5% donor CD3 lymphocytes. PT demonstrated lymphodepleting effects and promising safety, supporting alloNST as early as 7 days after initiation of PT.

Anti-third-party veto CTLs overcome rejection of hematopoietic allografts: synergism with rapamycin and BM cell dose

Several bone marrow cells and lymphocyte subpopulations, known as "veto cells," were shown to induce transplantation tolerance across major histocompatibility antigens. Some of the most potent veto cells are of T-cell origin, and in particular a very strong veto activity was documented for cytotoxic T-lymphocyte (CTL) lines or clones. However, these cells also possess marked graft-versus-host (GVH) reactivity. In the present study we evaluated a new approach to deplete CTLs of antihost clones by stimulating the donor T cells against third-party stimulators in the absence of exogenous interleukin 2 (IL-2). We demonstrate that such CTLs are depleted of GVH reactivity while maintaining marked veto activity in vitro. Furthermore, marked synergism was exhibited between the veto CTLs and rapamycin when tested in a murine model, which measures T-cell-mediated bone marrow allograft rejection, or in sublethally irradiated allogeneic hosts. Our results suggest that engraftment of early progenitors could be enhanced by using host-nonreactive anti-third-party CTLs, in conjunction with nonmyeloablative rapamycin-based conditioning protocols, thereby significantly reducing the toxicity of allogeneic transplantation.

A new minimally ablative stem cell transplantation procedure in high-risk patients not eligible for nonmyeloablative allogeneic bone marrow transplantation

Nonmyeloblative stem cell transplantation (NST, SCT) aims to induce host-versus-graft tolerance for subsequent immunotherapy of underlying disease with alloreactive donor lymphocytes, focusing on well-tolerated conditioning suitable for elderly individuals or for other risk factors. However, there is a subset of high-risk patients who cannot tolerate NST. A new protocol consisting of fludarabine 30 mg/m(2) x 6 days (days -8 to -2), very-low-dose busulfan (2 mg/kg x 2 days, days -6 to -5), without anti thymocyte globulin (ATG), was employed in 11 high-risk patients aged 26-58 years. Graft-versus-host-disease (GVHD) prophylaxis consisted of low-dose and short-course cyclosporine-A (CSA) alone. One patient died during the nadir due to pulmonary complications. Other patients showed rapid three-lineage engraftment, without complete aplasia; 6/10 patients did not require platelet transfusion and 8/10 had full donor chimerism without transient mixed chimerism. Owing to intentional selection of highly poor-risk patients, overall mortality was high and only one patient survived. Acute GVHD (>/=grade I) occurred in 8/10 evaluable patients, 5/8 while off CSA; 5/8 developed grade III-IV acute GVHD. It appears that our modified, minimally ablative stem cell transplantation (MST) may be used for high-risk patients in need of allo-SCT. Furthermore, although the MST conditioning is not myeloablative, it results in myeloablation of the host hematopoietic system, mediated by alloreactive lymphocytes.

The graft versus leukemia response after allogeneic hematopoietic stem cell transplantation

It is now well established that the efficacy of allogeneic hematopoietic stem cell transplant for eradicating a variety of hematologic malignancies is related to antitumor activity mediated by donor immune cells contained in the stem cell graft. Recent studies have provided fundamental insights into the nature of the effector cells and target molecules that are responsible for the graft versus tumor effect. T cells specific for minor histocompatibility antigens can mediate potent antitumor activity but are also responsible for graft versus host disease (GVHD). The molecular characterization of minor antigens has suggested ways of potentially separating antitumor activity from GVHD. The challenge for the future is to continue to build on our understanding of the allogeneic graft versus tumor effect and develop strategies that can be incorporated into clinical practice to augment this effect without GVHD.

Rapid and complete donor chimerism in adult recipients of unrelated donor umbilical cord blood transplantation after reduced-intensity conditioning

Reduced-intensity conditioning may reduce transplantation-related mortality in high-risk adults undergoing hematopoietic transplantation. We investigated unrelated donor umbilical cord blood (UCB) transplantation after such conditioning in 43 patients (median age, 49.5 years; range, 22-65 years) with a primary end point of donor engraftment. The first 21 patients received busulfan 8 mg/kg, fludarabine 200 mg/m2, and 200 cGy of total body irradiation (Bu/Flu/TBI). Subsequent patients (n = 22) received cyclophosphamide 50 mg/kg, fludarabine 200 mg/m2, and 200 cGy TBI (Cy/Flu/TBI). UCB grafts (93%) were 1-2 HLA antigen-mismatched with the recipient and contained a median cryopreserved cell dose of 3.7 x 107 (range, 1.6 x 107-6.0 x 107) nucleated cells per kilogram of recipient body weight (NC/kg). Graft versus host disease (GVHD) prophylaxis was cyclosporin A to day 180 plus mycophenolate mofetil to day 30. The cumulative incidence of sustained donor engraftment was 76% (95% confidence interval [CI], 56%-96%) for Bu/Flu/TBI recipients and 94% (95% CI, 84%-100%) for Cy/Flu/TBI recipients. The median day of neutrophil recovery (at least 0.5 x 109/L) for engrafting Bu/Flu/TBI recipients was 26 days (range, 12-30 days) and for Cy/Flu/TBI recipients was 9.5 days (range, 5-28 days). Incidence of grades III-IV acute GVHD was 9% (95% CI, 1%-17%), and survival at 1 year was 39% (95% CI, 23%-56%). These data demonstrate that 0-2 antigen mismatched UCB is sufficient to engraft most adults after reduced-intensity conditioning and is associated with a low incidence of severe acute GVHD.

Specific targeted therapy of chronic myelogenous leukemia with imatinib

Chronic myeloid leukemia (CML) is characterized by the Philadelphia translocation that fuses BCR sequences from chromosome 22 upstream of the ABL gene on chromosome 9. The chimerical Bcr-Abl protein expressed by CML cells has constitutive tyrosine kinase activity, which is essential for the pathogenesis of the disease. Imatinib, an ATP-competitive selective inhibitor of Bcr-Abl, has unprecedented efficacy for the treatment of CML. Most patients with early stage disease achieve durable complete hematological and complete cytogenetic remissions, with minimal toxicity. In contrast, responses are less stable in patients with advanced CML. This review highlights the pathogenesis of CML, its clinical features, and the development of imatinib as a specific molecularly targeted therapy. Aspects of disease monitoring and side effects are covered as well as resistance to imatinib and strategies to overcome resistance, such as alternative signal transduction inhibitors and drug combinations. Perspectives for further development are also discussed.

Monitoring bcr-abl by polymerase chain reaction in the treatment of chronic myeloid leukemia

The elucidation of the molecular biology of chronic myeloid leukemia (CML) has provided a paradigm for understanding leukemogenesis, targeted drug development, and disease monitoring at the molecular level. Minimal residual disease (MRD) monitoring by fluorescence in situ hybridization and polymerase chain reaction (PCR) has become an important tool in predicting relapse after allogeneic transplant, allowing for early intervention strategies such as donor lymphocyte infusion. MRD monitoring is important for assessment of disease status in patients who obtain a complete cytogenetic remission, and this approach is likely to play an important role in following patients to determine who will relapse on imatinib mesylate therapy. This review focuses primarily on MRD monitoring by PCR.

Effective graft-versus-leukaemia effect after allogeneic stem cell transplantation using reduced-intensity preparative regimens in Fanconi anaemia patients with myelodysplastic syndrome or acute myeloid leukaemia

Allogeneic transplantation is the only curative treatment for Fanconi anaemia (FA) patients who develop myeloid malignancies. Dose-intensive preparative regimens, to decrease disease recurrence, lead to unacceptable transplant-related toxicity in FA. We report the outcome of three FA patients with such malignancies who underwent transplantation with reduced-intensity preparative regimens. This approach was well tolerated, even as second transplantations, and resulted in complete leukaemic remissions. However, the graft-versus-leukaemia effect was associated with fatal graft-versus-host disease. Even after transplantation, myeloid malignancies remain associated with a poor outcome in FA, and this argues in favour of early intervention when suitable donors are available.

Early reconstitution of the T-cell repertoire after non-myeloablative peripheral blood stem cell transplantation is from post-thymic T-cell expansion and is unaffected by graft-versus-host disease or mixed chimaerism

To study immune recovery after non-myeloablative, reduced-intensity stem cell allografts (NST) and T-cell-depleted myeloablative transplants (TCD), we measured T-cell subset recovery by flow cytometry, T-cell repertoire by spectratyping and thymic T-cell output using a T-cell receptor excision circle (TREC) assay. We found a rapid and comparable increase in lymphocyte numbers in both NST and TCD, supporting the presence of a powerful drive for lymphocyte recovery after transplant. Spectratyping on d 45 and 100 revealed almost complete normalization of the T-cell repertoire in NST patients by d 45, whereas TCD patients demonstrated marked skewing of the repertoire, persisting to d 100. After NST, there was a significantly higher number of TREC-positive CD4+ and CD8+ cells (P = 0.02 and P = 0.01 respectively). However, in both NST and TCD, early T-cell recovery after transplant appeared to result entirely from post-thymic T cells, the expansion pattern of which is most influenced by the starting T-cell dose, but not markedly by graft-versus-host disease (GVHD) or mixed chimaerism. These results define important qualitative differences in the T-cell repertoire according to the type of transplant schedule used.

Regimen-related toxicity after fludarabine-melphalan conditioning: a prospective study of 31 patients with hematologic malignancies

A total of 31 consecutive patients with hematologic malignancies who were considered poor candidates for TBI underwent allogeneic stem cell transplantation after conditioning with fludarabine and melphalan. A total of 25 matched sibling recipients received fludarabine 25 mg/m(2) x 5 days and melphalan 70 mg/m(2) x 2 days. For unrelated and haploidentical donor recipients, fludarabine was increased to 30 mg/m(2) and ATG 30 mg/kg x 4 days was added. Graft-versus-host disease prophylaxis consisted of tacrolimus and mini methotrexate. All patients engrafted. Regimen-related toxicity was considerable and included mainly renal, hepatic and mucosal toxicity. There were seven regimen-related-deaths including two VOD, two pulmonary, one renal, one cardiac and one mucosal toxicity. One case of fatal pulmonary toxicity death could be attributed to pre-existing pulmonary damage. Progression-free survival at 12 months was 44% (90% CI: 30-58%) for recipients of HLA-identical sibling transplants and 33% (90% CI: 21-45%) for all patients. In conclusion, the fludarabine-melphalan regimen leads to consistent engraftment. The regimen-related toxicity is considerable and cannot be explained solely by patient selection. Cardiac toxicity is emerging as a unique toxicity of this regimen. Despite toxicity, fludarabine-melphalan has considerable activity and leads to durable remission in a proportion of patients.

Chronic myelogenous leukemia

The treatment options for chronic myelogenous leukemia (CML) continue to evolve rapidly. Imatinib mesylate (Gleevec, Glivec, formerly STI571) has continued to show remarkable clinical benefits and the updated results with this agent are reviewed. As relapses using single agent imatinib have occurred, particularly in advanced phase patients, the issue of whether combinations of other antileukemic agents with imatinib may yield improved results is addressed. In addition, data on new agents that have potential in the treatment of CML are reviewed. These agents are presented in the context of their molecular mechanism of action. The most recent data for stem cell transplantation, along with advances in nonmyeloablative transplants, are also reviewed. In Section I, Drs. Stephen O'Brien and Brian Druker update the current status of clinical trials with imatinib and review ongoing investigations into mechanisms of resistance and combinations of imatinib with other agents. They also present their views on integration of imatinib with other therapies. In Section II, Dr. Jorge Cortes describes the most recent data on novel therapies for CML, including farnesyl transferase inhibitors, arsenic trioxide, decitabine, and troxatyl, among others. These agents are discussed in the context of their molecular mechanism of action and rationale for use. In Section III, Dr. Jerald Radich updates the results of stem cell transplants for CML, including emerging data on nonmyeloablative transplants. He also presents data on using microarrays to stratify patients into molecularly defined risk groups.

Durable remissions of myelodysplastic syndrome and acute myeloid leukemia after reduced-intensity allografting

PURPOSE

To evaluate the use of reduced-intensity (RI) conditioning with allogeneic hematopoietic stem cell transplantation (HSCT) from HLA-identical family donors in patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).

PATIENTS AND METHODS

Sixteen patients (median age, 54 years; range, 37 to 66 years) underwent RI-HSCT using a conditioning regimen of fludarabine 25 mg/m2 daily for 5 days and either cyclophosphamide 1 g/m2 daily for 2 days (14 patients) or melphalan 140 mg/m2 for 1 day (two patients). The median number of CD34+ cells and CD3+ cells infused per kilogram of recipient weight was 4.5 x 106 (range, 1.8 to 7.3 x 106 cells) and 2.9 x 108 (range, 0.1 to 9.6 x 108 cells), respectively.

RESULTS

There was no transplant-related mortality (TRM) within 100 days of HSCT. Grade 1 to 2 acute graft-versus-host disease (GVHD) occurred in three patients, but neither grade 3 nor grade 4 disease was observed. Chronic GVHD occurred in 10 patients. One patient had cytomegalovirus (CMV) reactivation but did not develop CMV disease. With a median follow-up of 26 months (range, 15 to 45 months), 11 patients are alive (nine in continuous complete remission and one in complete remission after a second transplantation), and five have died (four from disease progression and one from bone-marrow aplasia induced by cyclosporine withdrawal). The 2-year actuarial overall and event-free survival rates were 69% (95% confidence interval [CI], 40% to 86%) and 56% (95% CI, 30% to 68%), respectively.

CONCLUSION

This strategy of RI-HSCT resulted in reliable engraftment with low incidence of acute GVHD and TRM. Durable remissions were observed in patients with MDS and AML consistent with a graft-versus-leukemia effect.

Transfusion-free reduced-intensity conditioned allogeneic stem cell transplantation in a Jehovah's witness

With an estimated 6000000 Jehovah's witnesses worldwide, haematologists may encounter patients who decline blood transfusions as a matter of personal belief. Here, we describe the first case of a transfusion-free allogeneic stem cell transplant (SCT) in a Jehovah's witness with CML. The patient underwent HLA-identical peripheral blood SCT after reduced-intensity conditioning with total body irradiation and fludarabine. Conditioning and the period after transplantation were uneventful, complete donor chimerism was achieved and the patient continues to be in molecular remission without significant chronic graft-versus-host disease. When treating Jehovah's witnesses with diseases that may be cured by allogeneic SCT, this approach should be kept in mind.

Conditioning with fludarabine and targeted busulfan for transplantation of allogeneic hematopoietic stem cells

A regimen of busulfan and cyclophosphamide is standard therapy before transplantation of allogeneic hematopoietic stem cells in patients with chronic myelogenous leukemia (CML) or myelodysplastic syndrome (MDS). The clinical trial reported here was undertaken to test the hypothesis that fludarabine can replace cyclophosphamide in this regimen and facilitate donor engraftment with reduced toxicity. The conditioning regimen consisted of 30 mg/m2 intravenous fludarabine daily from day -9 to day -6, and oral busulfan given at 1 mg/kg 4 times a day every 6 hours from day -5 to day -2, with doses adjusted to target plasma levels of 900 +/- 100 ng/mL at steady state. Cyclosporine and methotrexate were used for prophylaxis for graft-versus-host disease. Enrolled were 42 patients with high-risk CML (n = 4) or MDS (n = 38). The median patient age was 52 years (range, 12-65 years). Mobilized blood stem cells were obtained from HLA-compatible siblings (n = 16) or unrelated donors (n = 26). Engraftment was achieved in all patients, and the day-100 regimen-related mortality was 7%. With a median follow-up of 18 months (range, 13-27 months), the probabilities of overall survival, disease-free survival, and nonrelapse mortality were 42.4%, 34.9%, and 24%, respectively. These data indicate that the combination of fludarabine and targeted busulfan is sufficiently immunosuppressive to facilitate engraftment of blood stem cells from HLA-matched siblings and unrelated donors. Based on these encouraging results, further studies of fludarabine and targeted busulfan are warranted in standard-risk patients.

Present results and perspectives of allogeneic non-myeloablative hematopoietic stem cell transplantation for treatment of human solid tumors

Several clinical observations have confirmed that a donor immune-mediated anti-malignancy effect, called graft-versus-leukemia or graft-versus-tumor, occurs following allogeneic hematopoietic stem cell transplantation. While the potential antitumor effect mediated by donor lymphocytes has been established in many hematological malignancies, its efficacy in inducing clinically meaningful responses in solid tumors has been largely unexplored despite evidence of its potential benefit in experimental animal models. Only in recent years has the investigational application of non-myeloablative stem cell transplantation in patients with refractory non-hematological cancers proved that a graft-versus-tumor effect can be generated in patients with metastatic renal cell cancer and possibly with other solid tumors. In the present article we review the biological basis, development and early clinical results of this novel immunotherapeutic approach for solid tumors.

Risks and outcomes of invasive fungal infections in recipients of allogeneic hematopoietic stem cell transplants after nonmyeloablative conditioning

The incidence of invasive mold infections has increased during the 1990s among patients undergoing allogeneic hematopoietic stem cell transplantation (HCT) after myeloablative conditioning. In this study, we determined risk factors for invasive mold infection and mold infection-related death among 163 patients undergoing allogeneic HCT with nonmyeloablative conditioning. The cumulative incidence rates of proven or probable invasive fungal infections, invasive mold infections, invasive aspergillosis, and invasive candidiasis during the first year after allogeneic HCT with nonmyeloablative conditioning were 19%, 15%, 14%, and 5%, respectively, which were similar to those after conventional myeloablative HCT. Invasive mold infections occurred late after nonmyeloablative conditioning (median, day 107), with primary risk factors including severe acute graft-versus-host disease (GVHD), chronic extensive GVHD, and cytomegalovirus (CMV) disease. The 1-year survival after diagnosis of mold infections was 32%. High-dose corticosteroid therapy at diagnosis of mold infection was associated with an increased risk for mold infection-related death. Overall, nonrelapse mortality was estimated at 22% (36 patients) after nonmyeloablative conditioning, of which 39% (14 patients) were mold infection-related (9% of the overall mortality). More effective strategies are needed to prevent invasive mold infections, which currently account for a notable proportion of nonrelapse mortality after nonmyeloablative allogeneic HCT.

Impact of CD34+ cell dose on the outcome of patients undergoing reduced-intensity-conditioning allogeneic peripheral blood stem cell transplantation

We analyzed the impact of CD34+ cell dose on the outcome of 86 patients undergoing reduced-intensity conditioning (RIC) allogeneic peripheral blood stem cell transplantation. The RIC was based on fludarabine 150 mg/m2 and melphalan 140 mg/m2 or busulphan 10 mg/kg. A median of 5.68 x 106 CD34+ cells/kg and 2.86 x 108 CD3+ cells/kg were infused. All patients receiving more than percentile 75 (p75) of CD34+ cells reached complete chimerism in T lymphocytes by days 21 to 28, compared with 44% among those receiving p75 or fewer cells (P =.046). Overall, 30.3% patients developed grade 2 to 4 acute graft-versus-host disease (aGVHD). Among 83 evaluable patients, 55.8% developed chronic GVHD (cGVHD). The dose of CD34+ cells infused did influence the development of cGVHD, with a cumulative incidence of extensive cGVHD of 74% vs 47% (P =.02) among patients receiving more than p75 CD34+ cells vs those receiving p75 or fewer. Projected overall survival (OS) and event-free survival (EFS) at 43 months were 60% and 46%, respectively. Neither the dose of CD34+ cells nor the dose of CD3+ cells infused significantly influenced OS and EFS, although among patients categorized as high-risk, 36% of those receiving p75 or fewer CD34+ cells relapsed or progressed, compared with only 9% among those receiving more than p75 CD34+ cells (P =.07). Among patients receiving p75 or fewer CD34+ cells, 36% of high-risk patients relapsed, compared with 10% of low- and intermediate-risk patients (P =.004), while relapse rates were not significantly different between both subgroups when we infused more than p75 CD34+ cells, thus indicating that infusing high doses of CD34+ cells ameliorates the negative effect of advanced disease status at transplantation. cGVHD was associated with better EFS (63% vs 16% at 43 months for patients with and without cGVHD; P <.0001) and better OS (78% vs 28% for patients with and without cGHVD; P <.001). The number of CD34+ cells infused should be tailored to prevent extensive cGVHD among patients categorized as low-risk, while high-risk patients, in whom the graft-versus-leukemia effect may determine disease outcome, should receive high doses of CD34+ cells.

ABO mismatch increases transplant-related morbidity and mortality in patients given nonmyeloablative allogeneic HPC transplantation

BACKGROUND

ABO mismatch has not been thought to affect the outcome of patients undergoing myeloablative conditioning and allogeneic HPC transplantation. Data on transplant-related complications after ABO-mismatched transplantation after nonmyeloablative conditioning are limited.

STUDY DESIGN AND METHODS

Therefore, 40 patients were analyzed after nonmyeloablative conditioning with regard to ABO compatibility. Eleven received a minor and bidirectional and 8 a major ABO-mismatched graft.

RESULTS

Four patients had evidence of hemolysis during engraftment, being lethal in one, and three developed pure RBC aplasia. Six patients in the ABO-mismatched group developed thrombotic microangiopathy, and three of them died. ABO-identical and ABO-mismatched patients had a similar incidence of GVHD. Viral infections occurred in both groups in equal shares. Patients with an ABO-mismatch had to be rehospitalized until Day 100 for a median of 19 days versus 0 days in the identical group (p < 0.05). Overall survival was 60 and 57 percent in the ABO-identical and ABO-mismatch groups, respectively. The probability of transplant-related mortality was 0 versus 28 percent in the identical group compared to patients with an ABO mismatch (p < 0.05). The probability of relapse or progression was 76 versus 25 percent in the ABO-identical group compared to the ABO-mismatched group, respectively.

CONCLUSION

Significantly more patients with ABO mismatch showed transplant-associated complications and died as a result of transplant-related causes.

The marrow stem cell: the continuum

The marrow hematopoietic stem cell is currently being redefined as to all aspects of its phenotype and its total differentiation capacity. This redefinition now includes its plasticity as to production of nonhematopoietic and hematopoietic cell types, the determinants of its in vivo engraftment potential and its expression of stem cell functional characteristics.

Reduced-intensity conditioning followed by allogeneic hematopoietic cell transplantation in myeloid diseases

Within the past years, reduced or modified doses of chemotherapy or radiotherapy have been widely studied for conditioning before allogeneic hematopoietic cell transplantation in patients with myeloid leukemia not eligible for conventional transplantation. The main goal was to reduce the substantial treatment-related mortality in this patient population while preserving the potential curative graft-versus-leukemia effect. This review summarizes results of published trials using reduced-intensity conditioning (RIC) in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), chronic myeloid leukemia (CML), and myelofibrosis. In most of the published trials conditioning contained fludarabine (90-180 mg/m(2)) in combination with busulfan (4 x 10 mg/kg), melphalan (90-140 mg/m(2)), or 2-5 Gy total body irradiation (TBI). Peripheral blood hematopoietic stem cells from related or unrelated donors were used as graft source in most of the studies. Post-transplantation immunosuppression consisted of cyclosporine combined with methotrexate or mycophenolate mofetil. Although the majority of the patients were above the age of 50 years, early treatment-related mortality was rather low. Nevertheless, the rate of clinically significant graft-versus-host disease (GVHD) seemed to be comparable to conventional transplants in most of the protocols. The outcome differed between trials, but diagnosis and disease status pre-transplant significantly influenced outcome. In summary, this approach is feasible and provides access to the curative potential of allogeneic stem cell transplantation for patients with higher age or comorbidities. Since the majority of the reports included heterogeneous patient populations, mostly with a short follow-up, more and specifically randomized studies are needed to define the role of RIC before allogeneic hematopoietic cell transplantation.

Non-myeloablative hematopoietic cell transplantation as immunotherapy for hematologic malignancies

Conventional approaches to hematopoietic stem cell transplantation (HSCT) carry risks of morbidity and mortality from regimen-related toxicities, which have restricted the procedure to relatively young patients in good medical condition. This age restriction is unfortunate because the median age of patients with most candidate diseases (e.g., acute and chronic leukemias, myelodysplasia, myeloproliferative diseases, myeloma, and non-Hodgkin lymphoma) for HSCT is greater than 60 years. In non-myeloablative allogeneic HSCT, high-dose cytotoxic therapy as the conceptual basis for treating hematopoietic malignancies has been replaced by graft-versus-tumor effects. The use of potent pre- and postgrafting immunosuppression derived from preclinical studies has allowed omission of myeloablative cytotoxic therapy without compromising hematopoietic donor cell engraftment. This results in a marked reduction in transplant-related toxicities which makes older or medically infirm patients candidates for this treatment option. Initial results in patients with a variety of hematologic malignancies have been encouraging, with documented sustained cytogenetic and molecular remissions in a substantial number of sometimes heavily pretreated and previously refractory patients. While patients with hematologic malignancies will likely require conversion to full donor hematopoiesis for long-term disease control, a state of mixed donor/host hematopoietic chimerism might suffice to 'cure' the disease phenotypes in various non-malignant diseases. Strategies aimed at inducing donor-specific tolerance and optimizing post-transplant immunosuppression may eventually eliminate the need for pre-transplant total body irradiation which is relevant for minimizing late toxicities.

A single intravenous infusion of apoptotic cells, an alternative cell-based therapy approach facilitating hematopoietic cell engraftment, did not induce autoimmunity

Previously, we reported that intravenous infusion of apoptotic leukocytes facilitated bone marrow (BM) engraftment across major histocompatibility barriers. This cell-based therapeutic approach is of great interest for stem cell therapy across histocompatibility barriers. Autoimmunity associated with apoptotic cell administration may, however, limit the use of this approach. Indeed, autoantigens are concentrated on the surface of apoptotic cells, and defective clearance of apoptotic bodies is associated with the occurrence of systemic autoimmune disease. In consequence, we assessed the autoimmune responses raised against ubiquitous double-stranded DNA (dsDNA) and cardiolipin autoantigens following a single intravenous infusion of apoptotic cells simultaneously to allogeneic BM administration. No difference was observed between levels of natural circulating immunoglobulin M (IgM) (anti-dsDNA and anti-cardiolipin) autoantibodies found in mice receiving allogeneic BM alone and those found in mice receiving apoptotic cells also. Pathogenic IgG autoantibody titers after apoptotic cell infusion were 9- to 200-fold lower than autoantibody titers found in lupus-prone mice and not different from titers detected in BM grafted mice. Kinetic analysis of autoantibodies after transplantation did not demonstrate any immunization against tested autoantigens after apoptotic cell infusion. Finally, neither immune complex deposition nor specific lesions were observed in the renal glomeruli of mice infused with apoptotic cells 9 months post-BM transplantation. Overall, these results show no specific toxicity of a single infusion of apoptotic cells administrated simultaneously to BM and may also shed light on factors influencing the immunogenic properties of apoptotic cells.

Donor lymphocyte infusion-mediated graft-versus-leukemia effects in mixed chimeras established with a nonmyeloablative conditioning regimen: extinction of graft-versus-leukemia effects after conversion to full donor chimerism

BACKGROUND

We investigated an approach to separating graft-versus-lymphoma (GVL) effects from graft-versus-host disease (GVHD) in mice receiving a nonmyeloablative conditioning regimen allowing establishment of mixed hematopoietic chimerism.

METHODS

We evaluated the ability of donor lymphocyte infusions (DLI) to mediate GVL effects without GVHD in mixed chimeras prepared with cyclophosphamide, anti-T-cell antibodies, and thymic irradiation. To examine the fate of GVH-reactive donor CD8+ T cells, we used the 2C T-cell receptor (TCR) transgenic mouse strain, which carries an Ld-specific transgenic TCR on the B6 background.

RESULTS

Administration of DLI on day 35 post-BMT led to conversion from mixed to full donor chimerism and mediated a powerful GVL effect with complete protection (100% survival) against mortality induced by a host-type lymphoma (EL4) administered 7 days later (100% mortality in non-DLI controls; P<0.001). No GVHD occurred in DLI recipients. Rechallenging the surviving DLI recipients, which had converted to full chimerism, with the same tumor dose 17 weeks later led to rapid tumor mortality. Long-term DLI recipients had anti-host proliferative responses, but not CTL responses in vitro. When given as DLI together with wild-type spleen cells, marked expansion of GVH-reactive 2C CD8+ T cells was observed on day 10, followed by a marked decline in their numbers by week 10 post-DLI.

CONCLUSIONS

Nonmyeloablative induction of mixed chimerism followed by administration of DLI can mediate powerful GVL effects. The late loss of DLI-mediated GVL effects may reflect the eventual loss of donor-derived GVH-reactive CTL, which occurs in association with conversion to full donor chimerism.

Rapid establishment of long-term culture-initiating cells of donor origin after nonmyeloablative allogeneic hematopoietic stem-cell transplantation, and significant prognostic impact of donor T-cell chimerism on stable engraftment and progression-free survival

BACKGROUND

Nonmyeloablative allogeneic hematopoietic stem-cell transplantation (NST) allows establishment of donor hematopoiesis without eradication of recipient stem cells by chemoradiotherapy. Quantification of donor chimerism may predict graft failure and relapse.

METHODS

We quantified donor long-term culture-initiating cells (LTC-IC) in nine patients during the early phase after NST and lineage-specific donor cells of myeloid (CD33+, CD34+, granulocytes) and lymphoid lineage (CD3+, CD4+, CD8+, CD56+) in 38 patients with a median follow-up of 40 weeks after NST. Conditioning therapy consisted of fludarabine 90 mg/m2 followed by total body irradiation of 2 Gy.

RESULTS

Only rapid establishment of donor T-cell chimerism was essential for stable donor engraftment. Patients with less than 90% of donor T cells 4 weeks after NST had a significantly higher risk of relapse, graft rejection, or both (14 of 18 patients) than patients with donor T-cell chimerism of 90% and higher (3 of 20 patients). Although conditioning therapy was nonmyeloablative, a significant decrease of repopulating stem cells defined as LTC-IC was seen after 2 weeks followed by rapid recovery of LTC-IC to pretransplant values. Interestingly, all LTC-IC were from donor origin 2 and 4 weeks after NST, but rapid establishment of donor LTC-IC was not predictive for progression-free survival.

CONCLUSIONS

Rapid establishment of lymphoid but not myeloid donor chimerism is a prognostic factor for stable donor engraftment after NST. It seems that an immunologic shield of alloreactive donor T cells is essential for early hematopoietic progenitors.

Graft-versus-host disease following allogeneic transplantation from HLA-identical sibling with antithymocyte globulin-based reduced-intensity preparative regimen

Reduced-intensity conditioning (RIC) regimens are increasingly used for allogeneic stem cell transplantation (allo-SCT). RIC has been shown to allow engraftment with minimal early transplantation-related mortality (TRM). However, in the context of RIC, predictive factors for acute and chronic graft-versus-host disease (aGVHD and cGVHD, respectively) and their effect on outcome remain unknown. In this report, we analyzed the outcome of 101 high-risk patients (70 hematologic and 31 nonhematologic malignancies) who received an HLA-identical sibling allo-SCT after RIC, including fludarabine, busulfan, and antithymocyte globulin (ATG). The cumulative incidence of grade II-IV aGVHD was 36% (95% confidence interval [CI], 27%-45%), whereas the cumulative incidence of cGVHD at 2 years was 43% (95% CI, 33%-53%). In multivariate analysis, the incidence of aGVHD was significantly associated with the ATG dose infused during conditioning (P =.0005), whereas peripheral blood as stem cell source was the only predictive factor for the development of cGVHD (P =.0007). The 1-year cumulative incidences of disease progression or relapse in patients with (n = 69) and without (n = 31) GVHD (whatever its form or grade) were 30% (95% CI, 19%-41%) and 55% (95% CI, 37%-72%), respectively (P =.02), suggesting that a potent graft-versus-tumor (GVT) effect can be achieved in high-risk patients following RIC. Moreover, the GVT effect was closely associated with GVHD without an increased risk of TRM (cumulative incidence of TRM, 18% [95% CI, 10%-25%]). Collectively, these results provide a framework for the refinement of RIC approaches designed to enhance the GVT effect with an acceptable risk of GVHD.

Graft-versus-host disease after nonmyeloablative versus conventional hematopoietic stem cell transplantation

It is unknown whether the severity, timing, and quality of graft-versus-host disease (GVHD) may be different after nonmyeloablative as compared with myeloablative hematopoietic stem cell transplantation (HSCT). Therefore, GVHD incidence, morbidity of skin, liver, and gut, requirements for immunosuppressive therapy, and survival were retrospectively analyzed in 44 patients who underwent nonablative HSCT and 52 who underwent ablative HSCT (median ages, 56 and 54 years, respectively). The nonablative transplantation regimen consisted of low-dose total body irradiation (TBI), preceded in some patients by fludarabine administration and followed in all patients by immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP). Those who underwent myeloablative HSCT were prepared with different TBI- and non-TBI-containing regimens and received CSP plus methotrexate or MMF for GVHD prophylaxis. The cumulative incidence of grades II-IV acute GVHD was lower after nonablative transplantation (64% vs 85%; P =.001), but there were no differences in the cumulative incidence of chronic GVHD requiring treatment (73% vs 71%; P =.96). Nonablative transplantation was associated with the delayed initiation of steroid treatment for GVHD (0.95 months vs 3.0 months; P <.001) and with the use of fewer systemic immunosuppressants in the first 3 months after transplantation (P </=.04). This corresponded to more prevalent skin and more severe gut morbidity 6 to 12 months after nonablative transplantation. Our results show that nonablative HSCT is associated with a syndrome of acute GVHD occurring after day 100 in many patients. This "late-onset acute GVHD" should be taken into consideration in the design of prospective studies comparing GVHD resulting from the two types of transplantation procedures.

The expanding applications of non-myeloablative stem cell transplantation

Non-myeloablative preparative strategies for allogeneic stem cell transplantation (SCT) have been increasingly utilized for a variety of hematological malignancies, solid tumours, and for tolerance induction. These regimens are associated with less transplant-related morbidity and mortality than conventional transplant conditioning regimens. It is not yet clear whether graft-vs.-host disease (GVHD) protection is afforded. Potent antitumour responses have been described in a variety of advanced malignancies. We have utilized a cyclophosphamide/anti-T-cell antibody therapy approach, which has resulted in the uniform induction of mixed chimerism. In many cases, this has served as an immunological platform for adoptive cellular immunotherapy (via donor leukocyte infusions). The results of this experience, as well as the outcomes of non-myeloablative stem cell transplantation (NST) for other malignant and nonmalignant conditions are described.

Steroid-refractory graft-vs.-host disease: past, present and future

Despite current standard preventive strategies that include optimizing donor selection and the combination of methorexate and a calcineurine inhibitor, acute and chronic GVHD remains a major barrier to successful hematopoietic cell transplantation for a sizeable proportion of patients. When acute and chronic GVHD become manifest a standard primary therapy approach has been the addition of glucocorticoid therapy to a background of calcineurine inhibition. When this approach fails patients with GVHD require secondary therapy. Ideally, second-line agents should promote transplantation tolerance so that the morbidity associated with prolonged use of glucocorticoids and other immunosuppressive agents can be minimized. Promising new agents or strategies which warrant further controlled clinical trials include: mycophenolate mofetil, sirolimus, humanized or chimeric monoclonal antibodies such as visilizumab, daclizumab and infliximab, and extracorporeal photopheresis. Co-operative studies are necessary to hasten the process of evaluating novel treatment strategies for acute and chronic GVHD.

Autologous recovery with protractedly undetectable donor chimerisms can precede stable donor engraftment in a nonmyeloablative cord blood transplant

Low levels of donor chimerism on day 28 after hematopoietic stem cell transplantation are highly predictive of a subsequent rejection of donor cells A recent report on nonmyeloablative transplants has demonstrated that patients who engrafted after transplantation had at least 10% donor cells detectable at this time point. A patient is described who received a nonmyeloablative umbilical cord blood transplant and experienced subsequent full engraftment of donor cells despite the absence of donor chimerism at 4 weeks posttransplantation.

High complete response rate after allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning regimens in advanced malignant lymphoma

The possible advantage of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a graft-versus-lymphoma effect. We explored the feasibility and efficacy of allo-HSCT with reduced-intensity (RI) regimens in advanced malignant lymphoma (ML). A total of 20 patients with indolent (n=9) or aggressive lymphoma (n=11) received allo-HSCT with an RI regimen (RIST). The preparative regimen consisted of a combination of purine analog and alkylating agent with or without antithymocyte globulin. A total of 11 patients had chemorefractory disease, seven had chemosensitive relapsed disease and two had residual disease. All of the patients received G-CSF-mobilized blood stem cells from HLA-matched siblings. Of the 20 patients, 19 achieved engraftment with acceptable regimen-related toxicities. Seven patients developed grade II-IV acute GVHD and 15 developed chronic GVHD. Of the 15 patients with evaluable disease, 12 achieved a complete response. One died of invasive fusariosis, four subsequently died of GVHD complicated with fungal infection and one died of progressive disease. With a median follow-up of 358 days, the Kaplan-Meier estimates for 1-year overall and progression-free survival were both 70%. The high response rate with low relapse observed in this study suggests that RIST may be an effective alternative curative treatment for patients with advanced ML.

Use of a reduced-intensity conditioning regimen for allogeneic transplantation in patients with chronic myeloid leukemia

Reduced-intensity conditioning that harnesses the potential of a graft-versus-tumor (GVT) effect has been proposed as an alternative to conventional myeloablative allogeneic stem cell transplantation. The primary aim is engraftment and this can be achieved with minimal immunosuppression. In this report, we describe the use of such regimens for CML in 17 patients who received human leukocyte antigen (HLA)-matched sibling allografts. Conditioning was with fludarabine, antithymocyte globulin (ATG) and busulfan for the first 11 patients, whereas fludarabine, busulfan and TBI were used for the remaining six patients. Engraftment was prompt in most of the cases. Complications and need for supportive therapy in the immediate post-transplant period were reduced drastically. Only two patients (both in the TBI group) died within the first 100 days. Acute graft-versus-host disease (GVHD) grade II-IV was seen in seven patients. Complications occurred later on. Chronic GVHD was observed in 11/17 patients. Lung infection and GVHD were the major killers. In surviving patients, after a median follow-up of 30 months (range 37-21 months), 6/17 (35.3%) are alive. Five are disease free and one patient is still in relapse even after a second donor lymphocyte infusion. Total treatment time and cost were more than with conventional transplants. We conclude that reduced-intensity transplantation still requires further refinement.

Predictive factors for outcome of allogeneic hematopoietic cell transplantation for adult acute lymphoblastic leukemia

Between January 1990 and December 1997, 182 adults with acute lymphoblastic leukemia (ALL) received allogeneic hematopoietic cell transplants according to Fred Hutchinson Cancer Research Center protocols. Patients eligible for transplantation included those in first remission, especially those at high risk of relapse (n = 41), and any patient in second or later remissions (n = 46) or in relapse (n = 95). The median patient age was 29.4 years (range, 18.0-57.6 years), and the median duration of disease was 13.3 months (range, 2.4-221.9 months). Fifty-six patients had Philadelphia chromosome-positive ALL. Most patients (n = 169) received a conditioning regimen of cyclophosphamide 120 mg/kg plus 12.0 to 15.75 Gy of total body irradiation and a combination of cyclosporine and methotrexate as graft-versus-host disease (GVHD) prophylaxis. One hundred twenty-one patients received stem cells from HLA-identical donors (88 related donors and 33 unrelated donors), and 61 received stem cells from HLA-mismatched donors (26 related donors and 35 unrelated donors). Actuarial disease-free survival at 5 years was 21% for all patients, 43% for patients in first remission, 24% for patients in second or later remissions, and 9% for patients in relapse. Univariate and multivariate Cox regression analyses were performed to identify factors associated with survival, relapse, nonrelapse mortality, and disease-free survival. Factors significantly associated (P <.01) with improved survival and disease-free survival included younger age and being in first remission. Lower disease-free survival was associated with receiving cyclosporine alone as GVHD prophylaxis (P <.01). Risk of relapse correlated only with disease status at transplantation: patients who underwent transplantation in relapse had a 9-fold increased risk compared with patients who underwent transplantation in first remission. Acute or chronic GVHD had no significant effect on relapse. Increased nonrelapse mortality was associated with HLA-mismatched donors, a positive cytomegalovirus serology before transplantation, and GVHD prophylaxis with only cyclosporine. Patients with Philadelphia chromosome-positive ALL had survival and relapse rates similar to patients with normal cytogenetics.

HLA-matched related hematopoietic cell transplantation for chronic-phase CML using a targeted busulfan and cyclophosphamide preparative regimen

Allogeneic blood or marrow transplantation (BMT) is a curative therapy for chronic myeloid leukemia (CML). We have previously reported that the pharmacologic targeting of busulfan combined with cyclophosphamide (TBU/CY) can minimize regimen-related toxicity while preserving antileukemic effects. We report here on 131 consecutive chronic-phase CML patients treated with allogeneic related BMT using a TBU/CY preparative regimen, where the busulfan dose was targeted to achieve a steady-state plasma concentration of at least 900 ng/mL. The median age of the patients was 43 years (range, 14-66 years). Estimates of the probabilities of nonrelapse mortality, relapse, survival, and disease-free survival 3 years after transplantation were 14%, 8%, 86%, and 78%, respectively. Age had no statistically significant effect on survival. Although approximately 60% of the patients developed clinically extensive chronic graft-versus-host disease, the median Karnofsky score at last contact date among survivors was 95%. Of surviving patients, 11% were molecularly positive for the bcr-abl mRNA at last contact, with a median level of bcr-abl transcripts of 4.6 copies/microg RNA. These data suggest that TBU/CY is a very effective preparative regimen for CML in chronic phase, associated with an expected survival at 3 years of approximately 85%, with most patients being in molecular remission.

Reduced toxicity and prompt engraftment after minimal conditioning of a patient with Fanconi anemia undergoing hematopoietic stem cell transplantation from an HLA-matched unrelated donor

Given the profound sensitivity of patients with Fanconi anemia to conventional conditioning regimens before hematopoietic stem cell transplantation (HSCT), we developed a minimally toxic regimen consisting of 2 Gy total body irradiation, 90 mg/m2 fludarabine, and postgrafting immunosuppression with cyclosporine and mycophenolate to treat FA patients undergoing HSCT from HLA-matched unrelated donors. With over 10 months follow-up, our first patient has complete and sustained engraftment. Graft-versus-host disease was limited to mild skin and liver and moderate gut manifestations. We conclude that the approach is well tolerated and ideally suited to reduce regimen-related toxicities while achieving sustained engraftment.

Role of autologous stem cell transplantation in chronic lymphocytic leukemia

Autologous hematopoietic stem sell transplantation is increasingly considered for treatment of patients with high-risk chronic lymphocytic leukemia. Patients not eligible for allogeneic hematopoietic stem cell transplantation with poor prognosis disease, documented chemosensitivity, and a minimal tumor burden at the time of hematopoietic stem cell transplantation can be treated with autologous hematopoietic stem cell transplantation currently using peripheral blood stem cells. Different purging methods to obtain sources of stem cells free of tumor contamination are currently being evaluated. Major concerns are judicious selection of which patients may benefit from this approach, the subsequent risk of relapse of disease, and the long-term risk of development of secondary malignancies, including myelodysplastic syndrome and acute myelogenous leukemia. Recognizing and reducing the risk factors that contribute to relapse and complications of the procedure should improve outcome after autologous hematopoietic stem cell transplantation. With the increasing use, increasing effectiveness, and low treatment-related mortality associated with nonmyeloablative conditioning regimens, the question of whether a patient should be offered autologous or allogeneic hematopoietic stem sell transplantation can be a difficult one. Defining salvage settings for relapse and implementing a tandem autologous/allogeneic hematopoietic stem cell transplantation approach may provide a method to improve outcome for selected patients.

Graft-versus-host disease, donor chimerism, and organ toxicity in stem cell transplantation after conditioning with fludarabine and melphalan

Hematopoietic stem cell transplantation may be used to induce a graft-versus-tumor effect against a range of malignancies. Pretransplantation conditioning regimens vary considerably in their degree of myelosuppression and immunosuppression, which may result in marked differences in the rate of T-cell engraftment and, as a consequence, the onset and severity of graft-versus-host disease (GVHD). We have examined the development of T-cell chimerism and the onset of GVHD following fludarabine and melphalan conditioning in 39 patients undergoing stem cell allografts from matched-sibling donors. Cyclosporin and short-course methotrexate were used as GVHD prophylaxis. Fatal regimen-related toxicity occurred in 4 patients. Rapid T-cell engraftment was found in all but 1 of the patients assessed, with more than 90% donor T-cell chimerism at 1 month posttransplantation. Of the evaluable patients, 43% developed grade 2-4 acute GVHD and 87% developed chronic GVHD (70% extensive). Overall, the combination of fludarabine and melphalan is intensely immunosuppressive, leads to rapid T-cell engraftment and results in substantial toxicity and GVHD, particularly in heavily pretreated patients.

Early lymphocyte recovery is an important determinant of outcome following allogeneic transplantation with CD34+ selected graft and limited T-cell addback

We evaluated the outcome of 29 patients (age 22-60 years), who received a CD34+selected related (n=16) or unrelated graft (n=13) with limited T-cell addback (TCAB) (median 5.9 x 10(4)/kg) following full-intensity conditioning for haematological malignancies. In all, 16 patients (55%) had either advanced disease or previous transplants. The cumulative incidences of grade 2-4 acute GVHD were 15.4 and 19.2% and that for chronic extensive GVHD were 35 and 37% in related and unrelated graft recipients, respectively. The strongest predictor of nonrelapse mortality and overall survival was the absolute lymphocyte count (ALC) at 30 days; patients with ALC<0.35 x 10(9)/l having an NRM and OS of 59.2 and 24.7%, compared to 10 and 90% in those with a higher ALC. Patients with acute leukaemia had poorer survival and this was associated with a lower ALC as well. Thus, TCAB with a CD34+ selected graft resulted in a comparable outcome in both older and younger patients, but the survival was strongly influenced by early lymphocyte recovery.

A comparison of T-, B- and NK-cell reconstitution following conventional or nonmyeloablative conditioning and transplantation with bone marrow or peripheral blood stem cells from human leucocyte antigen identical sibling donors

This retrospective study compares the reconstitution of T, B and NK cells in three groups of patients transplanted for haematological malignancies with grafts from their HLA-identical sibling donors. In all, 15 patients received PBSC after a nonmyeloablative conditioning regimen consisting of fludarabine and 200 cGy TBI, 13 patients received PBSC after myeloablative conditioning and 37 patients received BM after myeloablative conditioning. In the nonmyeloablative group, the NK cells normalised after 1 month, the CD8+ T cells normalised after 3 months, the CD4+ T cells reached near normal values after 9 months and the B cell values were reduced until 12 months after transplant. In the two myeloablative groups, recipients of PBSC had a significantly higher number of CD4+ T cells after 4 months (P=0.004) and after 12 months (P=0.001), than recipients of BM. We found no differences in the T cell reconstitution between the two PBSC groups. This was of interest as the recipients of nonmyeloablative conditioning were older (P<0.001) and had a higher occurrence of chronic GVHD (P<0.05) than the recipients of myeloablative conditioning. In contrast, the recipients of nonmyeloablative conditioning had a delayed B cell recovery when compared to the patients who received myeloablative conditioning (P=0.04).

Antithymocyte globulin affects the occurrence of acute and chronic graft-versus-host disease after a reduced-intensity conditioning regimen by modulating mixed chimerism induction and immune reconstitution

BACKGROUND

There have been no detailed analyses of the induction of donor cell-type chimerism, the onset and incidence of acute and chronic graft-versus-host disease (GVHD), and the immune recovery kinetics after reduced-intensity stem cell transplantation (RIST).

METHODS

To address these, with particular emphasis on the impact of the use of antithymocyte globulin (ATG) in RIST, we compared 39 consecutively registered patients who underwent RIST from an HLA-matched related donor and 33 patients who underwent conventional marrow-ablative transplantation.

RESULTS

The incidences of grades II to IV acute and chronic GVHD tended to be less in RIST with ATG than in either RIST without ATG or conventional marrow-ablative transplantation. In a multivariate analysis, the predictive factors for acute and chronic GVHD included, respectively, ATG and grades II to IV acute GVHD. In a chimerism analysis, the achievement of complete donor chimera in T-cell lineage was delayed in RIST without ATG compared with RIST with ATG (P=0.038), which might explain the observed delayed onset of acute GVHD in RIST with ATG compared with the other two regimens. The ratio of type 1 and 2 dendritic cells did not affect the development of GVHD, whereas the number of naive CD4+ T cells did. No difference was observed in the incidence of clinically definitive infection, including cytomegalovirus, among the three cohorts, regardless of the use of ATG.

CONCLUSIONS

We suggest that the conditioning regimen and immunosuppressive strategy after RIST should be carefully balanced against the risk of GVHD and of relapse of the basic disorder caused by the lack of a graft-versus-leukemia benefit.

Selective T-cell ablation with bismuth-213-labeled anti-TCRalphabeta as nonmyeloablative conditioning for allogeneic canine marrow transplantation

Two major immunologic barriers, the host-versus-graft (HVG) and graft-versus-host (GVH) reactions, have to be overcome for successful allogeneic hematopoietic cell transplantation. T cells were shown to be primarily involved in these barriers in the major histocompatibility complex identical setting. We hypothesized that selective ablation of T cells using radioimmunotherapy together with postgrafting immunosuppression would suffice to ensure stable allogeneic engraftment. We had described a canine model of nonmyeloablative marrow transplantation in which host immune reactions were impaired by a single dose of 200 cGy total body irradiation (TBI), and both GVH and residual HVG reactions were controlled by postgrafting immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP). Here, we substituted the alpha-emitter bismuth-213 (213Bi) linked to a monoclonal antibody (mAb) against T-cell receptor (TCR) alphabeta, using the metal-binding chelate diethylenetriaminepentaacetic acid (DTPA) derivative cyclohexyl-(CHX)-A", for 200 cGy TBI. Biodistribution studies using a gamma-emitting indium-111-labeled anti-TCRalphabeta mAb showed uptake primarily in blood, marrow, lymph nodes, spleen, and liver. Four dogs were treated with 0.13 to 0.46 mg/kg TCRalphabeta mAb labeled with 3.7 to 5.6 mCi/kg (137-207 MBq/kg) 213Bi. The treatment was administered in 6 injections on days -3 and -2 followed by transplantation of dog leukocyte antigen-identical marrow on day 0 and postgrafting immunosuppression with MMF/CSP. The therapy was well tolerated except for elevations of transaminases that were transient in all but one of the dogs. No other organ toxicities or signs of graft-versus-host disease were noted. The dogs had prompt allogeneic hematopoietic engraftment and achieved stable mixed donor-host hematopoietic chimerism with donor contributions ranging from 5% to 55% after more than 30 weeks of follow up.

The current status of hematopoietic cell transplantation

Hematopoietic cell transplantation is the preferred therapy for a substantial proportion of patients with life-threatening diseases of the lymphohematopoietic system. Recent advances in donor identification, disease eradication, and supportive care measures have broadened the application of transplantation and improved outcomes. This article provides a brief review of the major clinical principles of transplantation and results achieved to date.

Development of reduced-intensity hematopoietic stem cell transplantation in the National Cancer Center Hospital, Japan

Reduced-intensity hematopoietic stem cell transplantation (RIST) is a new approach of stem cell transplantation, which has shown promising features as reported in multiple phase I and II studies. Elderly patients, who are not eligible for conventional myeloablative hematopoietic stem cell transplantation (HSCT), are now treatable with RIST. It has also reduced regimen-related toxicity and provided better prognosis in short-term follow-up than that of conventional HSCT. Favorable results have been reported particularly in hematological malignancies, such as chronic myelocytic leukemia and malignant lymphoma. Among solid tumors, metastatic renal cell carcinoma was found to respond well to RIST. Clinical studies are currently being conducted to evaluate the efficacy of RIST in other types of solid tumors. However, the mechanism of graft-versus-host disease and graft-versus-tumor remains unclear. More knowledge on the mechanism is crucial to enhance antitumor effect and to further improve the prognosis.

Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation in patients with acute myeloid leukemia: disease status by marrow blasts is the strongest prognostic factor

We analyzed predictive factors for the outcome of 113 acute myeloid leukemia patients receiving reduced-intensity conditioning prior to allogeneic hematopoietic stem cell transplantation (HSCT). Patients were ineligible for conventional-intensity HSCT. Conditioning consisted of fludarabine and 50% of the conventional dose of busulfan (n=93) or total body irradiation (n=20). The source of stem cells was blood in 102 patients, marrow in 10, and both in one. In total, 50 (44.2%) donors were HLA-matched siblings, 50 (44.2%) unrelated fully matched and 13 (11.5%) partially mismatched family (n=1) or unrelated (n=12) donors. In all, 107 (94.6%) patients showed neutrophil and platelet engraftment after a median time of 13.5 and 13 days. The probabilities of event-free survival (EFS) (median follow-up: 12 months) were 49% for patients with less than 5% blasts in the marrow, 24% for patients with 5-20% blasts (P=0.002) and 14% with >20% blasts (P<or=0.001). Death occurred because of relapse in 29 patients (25.6%), infection in 12 patients (10.6%), acute graft-versus-host disease in eight patients (7.0%) and organ toxicity in nine patients (7.9%). In multivariate analysis, higher number of blasts in the marrow, alternative donors and low Karnofsky performance score were independent adverse prognostic factors for EFS.

Nonmyeloablative allogeneic hematopoietic stem cell transplantation for congenital sideroblastic anemia

Congenital sideroblastic anemia (CSA) is a dyserythropoietic disorder that leads to transfusion dependency and subsequent iron overload. Nonmyeloablative allogeneic hematopoietic stem cell transplantation (NST) was performed for a patient with CSA, who had contraindications to conventional allografting. Conditioning was fludarabine, low-dose total body irradiation and antithymocyte globulin, followed by peripheral blood stem cell transplant. Cyclosporine and mycophenolate mofetil were used for graft-versus-host disease prophylaxis. Complete donor chimerism was observed day +131. Early after transplant, the patient became transfusion independent, allowing a regular phlebotomy program. On day +190, refractory lactic acidosis followed by fatal cardiovascular collapse developed, without evidence of infection. Data from this case demonstrates that NST may correct the erythropoietic defect of CSA.

HLA-DRB1*16-restricted recognition of myeloid cells, including CD34+ CML progenitor cells

The therapeutic effect of a human leucocyte antigen (HLA)-identical allogeneic stem cell transplantation (allo-SCT) for the treatment of haematological malignancies is mediated partly by the allogeneic T cells that are administered together with the stem cell graft. Chronic myeloid leukaemia (CML) is particularly sensitive to this graft-versus-leukaemia (GVL) effect. Several studies have shown that in allogeneic responses both CD4 and CD8 cells are capable of strong antigen-specific growth inhibition of leukaemic progenitor cells, but that CD4 cells mainly exert the GVL effect against CML. Efficient activation of allogeneic CD4 cells, as well as CD8 cells, may explain the sensitivity of CML cells to elimination by allogeneic T cells. Identification of the antigens recognized by CD4 cells is crucial in understanding the mechanism through which CML cells are so successful in activating allogeneic T cells. In the present report, we describe the characterization of an allogeneic CD4 T-cell clone, DDII.4.4. This clone was found to react against an antigen that is specifically expressed in myeloid cells, including CD34+ CML cells. The antigen recognition is restricted by HLA-DRB1*16. To our knowledge, this is only the second report on an allogeneic CD4 T-cell clone that reacts with early CD34+ myeloid progenitor cells.

IL-2 does not enhance the conversion to complete donor chimerism following nonmyeloablative hematopoietic cell transplantation in dogs

A dog model of stable mixed hematopoietic chimerism was established in which leukocyte-antigen-identical littermates receive nonmyeloablative total body irradiation before hematopoietic cell transplantation and postgrafting immunosuppression with mycophenolate mofetil and cyclosporine. Unmodified donor lymphocyte infusion (DLI) into stable mixed chimeras failed to increase donor chimerism, while DLI from donors sensitized to recipient minor-histocompatibility antigens promptly converted all recipients to complete donor chimerism. This established a model for studying approaches to enhance the graft-versus-host (GVH)-effect, a potential surrogate for graft-versus-leukemia activity. We asked if interleukin-2 (IL-2) given after unmodified DLI could result in reliable conversion to complete donor chimerism. IL-2, 4 x 10(5) IU/kg/day, was administered to six mixed chimeric dogs for 14 days. Four dogs received unmodified DLI with IL-2. At 20-40 weeks after DLI, all dogs remained mixed chimeras. For the two recipients of IL-2 only, mixed chimerism also remained unchanged. These results show that IL-2 given with DLI after nonmyeloablative transplantation in dogs is not effective in reliably converting mixed to complete donor chimerism.