Graft-versus-tumor effects after allogeneic hematopoietic cell transplantation with nonmyeloablative conditioning

Comparative outcome of reduced intensity and myeloablative conditioning regimen in HLA identical sibling allogeneic haematopoietic stem cell transplantation for patients older than 50 years of age with acute myeloblastic leukaemia: a retrospective survey from the Acute Leukemia Working Party (ALWP) of the European group for Blood and Marrow Transplantation (EBMT)

Results of reduced intensity conditioning regimen (RIC) in the HLA identical haematopoietic stem cell transplantation (HSCT) setting have not been compared to those after myeloablative (MA) regimen HSCT in patients with acute myeloblastic leukaemia (AML) over 50 years of age. With this aim, outcomes of 315 RIC were compared with 407 MA HSCT recipients. The majority of RIC was fludarabine-based regimen associated to busulphan (BU) (53%) or low-dose total body irradiation (24%). Multivariate analyses of outcomes were used adjusting for differences between both groups. The median follow-up was 13 months. Cytogenetics, FAB classification, WBC count at diagnosis and status of the disease at transplant were not statistically different between the two groups. However, RIC patients were older, transplanted more recently, and more frequently with peripheral blood allogeneic stem cells as compared to MA recipients. In multivariate analysis, acute GVHD (II-IV) and transplant-related mortality were significantly decreased (P=0.01 and P<10(-4), respectively) and relapse incidence was significantly higher (P=0.003) after RIC transplantation. Leukaemia-free survival was not statistically different between the two groups. These results may set the grounds for prospective trials comparing RIC with other strategies of treatment in elderly AML.

Outcomes with Myeloid Malignancies

Reduced-intensity conditioning (RIC) regimens were initially introduced to provide allogeneic stem cell transplantation (HCT), a potentially curative procedure for myeloid malignancies, for patients who were not considered eligible for conventional myeloablative HCT either because of advanced age or excessive comorbidities. A variety of RIC regimens have been studied. The exact definition of RIC remains arbitrary and generally depends upon the perceived toxicity of a given regimen rather than the actual dose of chemotherapy or radiotherapy administered. In several published series, RIC regimens have demonstrated a reduction in non-relapse mortality (NRM), thereby accomplishing the initial goal of expanding the patient population eligible for this potentially curative procedure. Most retrospective studies performed to date have shown a decrease in NRM and an increase in relapse-related mortality with the use of RIC as opposed to conventional myeloablative HCT in myeloid malignancies. This appears to be particularly true for patients who are in relapse at the time of HCT. In contrast, patients who are in remission at time of HCT appear to have a reduction in NRM without a subsequent increase in relapse-related mortality. There is interest in applying RIC to younger patients and to patients with fewer comorbidities as they may have a reduction in NRM without a concomitant increase in relapse. Prospective multicenter studies are needed to define the optimal conditioning regimen, which is likely dependent upon a variety of disease-specific and patient-specific factors.

Reduced-intensity regimens in allogeneic stem-cell transplantation for non-hodgkin lymphoma and chronic lymphocytic leukemia

Autologous stem-cell transplantation is widely accepted as effective therapy for patients with relapsed aggressive B-cell non-Hodgkin lymphomas. Although 40-60% of younger patients with diffuse large cell lymphoma can expect to be cured, substantial numbers will experience a relapse. In addition, certain histologic subtypes are associated with particularly poor prognoses with combination chemotherapy alone (e.g., mantle cell lymphoma). Relatively few of these patients will experience long-term responses. Although other NHL subtypes are associated with more favorable prognoses in terms of overall survival, they are rarely cured (e.g., follicular lymphoma, chronic lymphocytic leukemia). Allogeneic transplantation has been increasingly utilized in patients with lymphoid malignancies but is associated with high toxicity. Recently, reduced-intensity conditioning regimens have shown encouraging results, attributed to graft-versus-lymphoma effects. This article discusses changes in the way autologous and allogeneic transplants may be carried out in the future to treat patients with lymphoid malignancies.

Cytokine Gene Expression in Peripheral Blood Mononuclear Cells and Alloreactivity in Hematopoietic Cell Transplantation with Nonmyeloablative Conditioning

Cytokines are thought to play an important role in the pathophysiology of graft-versus-host disease (GVHD). To study the relationship between cytokines and GVHD, we obtained peripheral blood mononuclear cells (MNCs) from 21 patients with hematologic malignancies and their HLA-identical sibling donors before and sequentially after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning. The MNCs were cultured for 72 hours either alone or in mixed lymphocyte cultures with irradiated MNCs of recipient, donor, or HLA-mismatched third-party origin. The gene expression of interleukin (IL)-2, IL-4, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta in each culture was then measured by real-time quantitative reverse transcriptase-polymerase chain reaction. The composition of the responder MNCs differed between patients and donors and changed after HCT, with a possible influence on the results. Early after transplantation (day +14), the IL-10 messenger RNA (mRNA) level in response to recipient or donor antigens was higher in patients who did not develop clinically significant acute GVHD when compared with the level in patients who subsequently developed acute GVHD grades II to IV (P = .005 and P = .004, respectively). The IL-10 mRNA level on day +14 was highly correlated with the pretransplantation mRNA level of the recipient MNCs but not with the level of the donor MNCs; this suggests that the IL-10 mRNA detected on day +14 originated from responder cells of recipient origin. A higher IL-10 mRNA level was found in MNCs obtained before transplantation from recipients whose disease progressed or relapsed after the transplantation when compared with the level in patients whose disease did not progress or relapse (P = .03). In conclusion, a high IL-10 gene expression in the recipient MNCs may be related to a reduced incidence of acute GVHD grades II to IV and a reduced graft-versus-tumor effect after HCT with nonmyeloablative conditioning.

Comparable results of umbilical cord blood and HLA-matched sibling donor hematopoietic stem cell transplantation after reduced-intensity preparative regimen for advanced Hodgkin lymphoma

We compared the safety and efficacy of allogeneic stem cell transplantation (allo-SCT) after reduced-intensity conditioning using either unrelated umbilical cord blood (UCB) donors or matched-sibling donors (MSDs) for 21 adults at high risk with advanced Hodgkin lymphoma (UCB, n = 9; MSD, n = 12). Both groups were comparable except for younger age in the UCB cohort (median, 28 vs 42 years; P = .02). Neutrophil recovery occurred earlier in the MSD group (median, 7 vs 10 days; P = .02). All patients had sustained donor engraftment by day 60. Cumulative incidence of acute severe graft-versus-host-disease (33% vs 33%; P = .99), chronic graft-versus-host-disease (11% vs 33%; P = .24), and 100-day treatment-related mortality (11% vs 17%; P = .80) were comparable. With median follow-up periods of 17 and 24 months, the 2-year progression-free survival rates were 25% (95% confidence interval [95% CI], 0%-55%) for UCB and 20% (95% CI, 0%-44%) for MSD allo-SCT (P = .67). Our results suggest comparable outcomes for reduced-intensity allo-SCT using UCB or MSD in adults at high risk with advanced Hodgkin lymphoma.

Allogeneic hematopoietic cell transplantation following nonmyeloablative conditioning as treatment for hematologic malignancies and inherited blood disorders

Allogeneic hematopoietic cell transplantation (HCT) after myeloablative conditioning regimens has been an effective treatment for many patients with hematologic malignancies or inherited blood disorders. Unfortunately, such regimens have been associated with significant toxicity, limiting their use to otherwise healthy, relatively young patients. In an attempt to extend treatment by allogeneic HCT to older patients and those with comorbid conditions, several groups of investigators have developed reduced-intensity or truly nonmyeloablative conditioning regimens, lacking such toxicity. Analogous to conventional regimens, reduced-intensity regimens both eliminated host-versus-graft (rejection) reactions and produced major anti-tumor effects. In contrast, nonmyeloablative regimens have relied on optimizing both pre-and posttransplant immunosuppression to overcome host-versus-graft reactions, while anti-tumor responses have depended mainly on immune-mediated graft-versus-tumor effects. In this review, we define reduced-intensity and truly nonmyeloablative regimens, describe the preclinical development and clinical application of a very low intensity nonmyeloablative regimen, and review results with reduced-intensity regimens in patients with hematologic malignancies or inherited blood disorders.

Current status of hematopoietic stem cell transplantation after nonmyeloablative conditioning

PURPOSE OF REVIEW

Allogeneic hematopoietic stem cell transplantation was originally developed as a form of rescue from high-dose chemoradiotherapy, which is given both to eradicate malignancy and provide sufficient immunosuppression for allogeneic engraftment. However, it was observed that allogeneic immunocompetent cells transplanted with the stem cells, or arising from them, mediated therapeutic antitumor effects independent of the action of the high-dose therapy. This was termed a graft-versus-tumor effect. This has prompted the recent development of nonmyeloablative conditioning regimens for allogeneic hematopoietic stem cell transplantation that have opened the way to include elderly patients and those with comorbid conditions.

RECENT FINDINGS

Recent retrospective studies comparing hematopoietic stem cell transplantation after myeloablative or nonmyeloablative regimens suggested that the use of nonmyeloablative conditioning might be associated with lower transplant-related toxicity, lower nonrelapse mortality, and at least similar intermediate-term progression-free survival.

SUMMARY

Hematopoietic stem cell transplantation after nonmyeloablative conditioning might become the procedure of choice also for younger patients. Phase 3 studies are needed to determine outcomes for different diseases and age groups.

Nonmyeloablative Stem Cell Transplantation for Myelodysplastic Syndrome or Acute Myeloid Leukemia in Patients 60 Years or Older

We analyzed the outcomes of 24 consecutive patients aged >or=60 years with poor-prognosis myelodysplastic syndrome or acute myeloid leukemia undergoing transplantation with nonmyeloablative conditioning using fludarabine (125 mg/m2) and low-dose total body irradiation (2 Gy) followed by allogeneic peripheral blood stem cell grafts from HLA-identical sibling donors. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mycophenolate mofetil. The median age of the patients was 64 years (range, 60-71 years). In addition to age, 88% of patients had 1 or more adverse biological features of the disease. With a median follow-up of 21 months, 12 patients are alive, 11 of whom are disease free. The probabilities of 2-year overall and progression-free survival were 52% and 44%, respectively. The cumulative probabilities of relapse and of acute and chronic GVHD were 27%, 45%, and 74%, respectively. Nonrelapse mortality at 100 days and 2 years was 8% and 25%, respectively. Of the 15 patients with extensive chronic GVHD, 1 patient relapsed. These data suggest that nonmyeloablative stem cell transplantation is a feasible treatment option in patients aged >or=60 years with poor-prognosis myelodysplastic syndrome or acute myeloid leukemia. The reasonable disease control with nonmyeloablative transplantation in this high-risk group of patients merits further investigation.

Graft-vs-host disease after non-myeloablative hematopoietic cell transplantation

Non-myeloablative preparative regimens have reduced regimen-related toxicities after allogeneic hematopoietic cell transplantation (HCT), which allows for the treatment of patients not eligible for myeloablative HCT. The reduced non-relapse mortality associated with non-myeloablative HCT is in part explained by the decreased incidence and severity of acute graft-vs-host disease (GVHD). Compared with conventional HCT, the onset of acute GVHD is delayed, and some patients may present with signs and symptoms characteristic of acute GVHD after day 100, in the absence of hallmarks of chronic GVHD. In contrast to the overall negative impact of acute GVHD on outcome, the net effects of chronic GVHD after non-myeloablative HCT appear to be beneficial, translating into improved progression-free survival among patients with different hematological malignancies. One obvious explanation for this beneficial effect is the strong association between chronic GVHD and protection against recurrent malignancy (graft-vs-tumor effect). Future strategies are aimed at reducing the risk of acute GVHD, in particular "early-onset" GVHD (before day 50), which is associated with increased non-relapse mortality and decreased overall survival, and at decreasing the corticosteroid dependence among patients who require immunosuppressive treatment for clinically established GVHD.

Hematopoietic cell transplantation (HCT)-specific comorbidity index: a new tool for risk assessment before allogeneic HCT

We previously reported that the Charlson Comorbidity Index (CCI) was useful for predicting outcomes in patients undergoing allogeneic hematopoietic cell transplantation (HCT). However, the sample size of patients with scores of 1 or more, captured by the CCI, did not exceed 35%. Further, some comorbidities were rarely found among patients who underwent HCT. Therefore, the current study was designed to (1) better define previously identified comorbidities using pretransplant laboratory data, (2) investigate additional HCT-related comorbidities, and (3) establish comorbidity scores that were suited for HCT. Data were collected from 1055 patients, and then randomly divided into training and validation sets. Weights were assigned to individual comorbidities according to their prognostic significance in Cox proportional hazard models. The new index was then validated. The new index proved to be more sensitive than the CCI since it captured 62% of patients with scores more than 0 compared with 12%, respectively. Further, the new index showed better survival prediction than the CCI (likelihood ratio of 23.7 versus 7.1 and c statistics of 0.661 versus 0.561, respectively, P < .001). In conclusion, the new simple index provided valid and reliable scoring of pretransplant comorbidities that predicted nonrelapse mortality and survival. This index will be useful for clinical trials and patient counseling before HCT.

High doses of transplanted CD34+ cells are associated with rapid T-cell engraftment and lessened risk of graft rejection, but not more graft-versus-host disease after nonmyeloablative conditioning and unrelated hematopoietic cell transplantation

This report examines the impact of graft composition on outcomes in 130 patients with hematological malignancies given unrelated donor granulocyte-colony-stimulating-factor-mobilized peripheral blood mononuclear cells (G-PBMC) (n = 116) or marrow (n = 14) transplantation after nonmyeloablative conditioning with 90 mg/m(2) fludarabine and 2 Gy TBI. The median number of CD34(+) cells transplanted was 6.5 x 10(6)/kg. Higher numbers of grafted CD14(+) (P = 0.0008), CD3(+) (P = 0.0007), CD4(+) (P = 0.001), CD8(+) (P = 0.004), CD3(-)CD56(+) (P = 0.003), and CD34(+) (P = 0.0001) cells were associated with higher levels of day 28 donor T-cell chimerism. Higher numbers of CD14(+) (P = 0.01) and CD34(+) (P = 0.0003) cells were associated with rapid achievement of complete donor T-cell chimerism, while high numbers of CD8(+) (P = 0.005) and CD34(+) (P = 0.01) cells were associated with low probabilities of graft rejection. When analyses were restricted to G-PBMC recipients, higher numbers of grafted CD34(+) cells were associated with higher levels of day 28 donor T-cell chimerism (P = 0.01), rapid achievement of complete donor T-cell chimerism (P = 0.02), and a trend for lower risk for graft rejection (P = 0.14). There were no associations between any cell subsets and acute or chronic GVHD nor relapse/progression. These data suggest more rapid engraftment of donor T cells and reduced rejection rates could be achieved by increasing the doses of CD34(+) cells in unrelated grafts administered after nonmyeloablative conditioning.

HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative conditioning for patients with chronic myeloid leukemia

We evaluated 10/10 HLA antigen-matched unrelated hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning with fludarabine 3 x 30 mg/m2 and 2 Gy of total body irradiation as treatment for patients with chronic myeloid leukemia who were ineligible for conventional HCT. Data from 21 consecutive patients in first chronic phase (CP1; n = 12), accelerated phase (AP; n = 5), second CP (CP2; n = 3), and blast crisis (n = 1) were analyzed. Stem cell sources were bone marrow (n = 4) or granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cells (G-PBMCs; n = 17). The patient who underwent transplantation in blast crisis died on day 21 (too early to be evaluated for engraftment) from progressive disease. Sustained engraftment was achieved in 5 of 12 patients who underwent transplantation in CP1, 4 of 5 patients who underwent transplantation in AP, and 2 of 3 patients who underwent transplantation in CP2, whereas 9 patients rejected their grafts between 28 and 400 days after HCT. Specifically, 1 of 4 marrow recipients and 10 of 17 G-PBMC recipients achieved sustained engraftment. Graft rejections were nonfatal in all cases and were followed by autologous reconstitution with persistence or recurrence of chronic myeloid leukemia. Seven of 11 patients with sustained engraftment--including all 5 patients in CP1, 2 of 4 patients in AP, and neither of the 2 patients in CP2--were alive in complete cytogenetic remissions 118 to 1205 days (median, 867 days) after HCT. Two of the remaining 4 patients died of nonrelapse causes in complete (n = 1) or major (n = 1) cytogenetic remissions, and 2 died of progressive disease. Further efforts are directed at reducing the risk of graft rejection by exclusive use of G-PBMC and increasing the degree of pretransplantation immunosuppression.