Survival after reduced-intensity conditioning is not inferior to standard high-dose conditioning before allogeneic haematopoietic cell transplantation in acute leukaemias

Allogeneic Stem Cell Transplantation in Patients >40 Years of Age With Acute Lymphoblastic Leukemia: Reduced Intensity Versus Myeloablative Conditioning

BACKGROUND

The outcome in older patients with acute lymphoblastic leukemia (ALL) remains unsatisfactory due to high relapse and nonrelapse mortality (NRM) rates. Allogeneic stem cell transplantation (alloHSCT) as postremission therapy has an important role in reducing relapse rate, albeit its application is limited in older adult patients due to alloHSCT-related morbidity and mortality. Reduced-intensity conditioning (RIC) alloHSCT has been developed as a less toxic conditioning regimen, but comparative studies with myeloablative conditioning (MAC) are limited in patients with ALL.

METHODS

In this retrospective study, RIC-alloHSCT (n = 111) was compared with MAC-alloHSCT (n = 77) in patients aged 41 to 65 y with ALL in first complete remission. MAC was predominantly applied by combining high-dose total body irradiation and cyclophosphamide, whereas RIC mainly consisted of fludarabine and 2 Gy total body irradiation.

RESULTS

Unadjusted overall survival was 54% (95% confidence interval [CI], 42%-65%) at 5 y in MAC recipients compared with 39% (95% CI, 29%-49%) in RIC recipients. Overall survival and relapse-free survival were not significantly associated with type of conditioning after adjusted for the covariates age, leukemia risk status at diagnosis, donor type, and donor and recipient gender combination. NRM was significantly lower after RIC (subdistribution hazard ratio: 0.41, 95% CI, 0.22-0.78; P  = 0.006), whereas relapse was significantly higher (subdistribution hazard ratio: 3.04, 95% CI, 1.71-5.40; P < 0.001).

CONCLUSIONS

Collectively, RIC-alloHSCT has resulted in less NRM, but it was also found to be associated with a significantly higher relapse rate. These results suggest that MAC-alloHSCT may provide a more effective type of consolidation therapy for the reduction of relapse and that RIC-alloHSCT may be restricted to patients at higher risk for NRM.

Incidence, Management, and Prognosis of Graft Failure and Autologous Reconstitution after Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

This study presents outcomes of management in graft failure (GF) after allogeneic hematopoietic stem cell transplantation (HCT) and provides prognostic information including rare cases of autologous reconstitution (AR).

METHODS

We analyzed risk factors and outcomes of primary and secondary GF, and occurrence of AR in 1,630 HCT recipients transplanted over period of 18 years (January 2000-September 2017) at our center.

RESULTS

Primary and secondary GF occurred in 13 (0.80%), and 69 patients (10-year cumulative incidence, 4.5%) respectively. No peri-transplant variables predicted primary GF, whereas reduced intensity conditioning (RIC) regimen (relative risk [RR], 0.97-28.0, P < 0.001) and lower CD34⁺ cell dose (RR, 2.44-2.84, P = 0.002) were associated with higher risk of secondary GF in multivariate analysis. Primary GF demonstrated 100% mortality, in the secondary GF group, the 5-year Kaplan-Meier survival rate was 28.8%, relapse ensued in 18.8%, and AR was observed in 11.6% (n = 8). In survival analysis, diagnosis of aplastic anemia (AA), chronic myeloid leukemia and use of RIC had a positive impact. There were 8 patients who experienced AR, which was rarely reported after transplantation for acute leukemia. Patient shared common characteristics such as young age (median 25 years), use of RIC regimen, absence of profound neutropenia, and had advantageous survival rate of 100% during follow period without relapse.

CONCLUSION

Primary GF exhibited high mortality rate. Secondary GF had 4.5% 10-year cumulative incidence, median onset of 3 months after HCT, and showed 5-year Kaplan-Meier survival of 28.8%. Diagnosis of severe AA and use of RIC was both associated with higher incidence and better survival rate in secondary GF group. AR occurred in 11.6% in secondary GF, exhibited excellent prognosis.

Comparison of Myeloablative versus Reduced-Intensity Conditioning Regimens in Allogeneic Stem Cell Transplantation Recipients with Acute Myelogenous Leukemia with Measurable Residual Disease-Negative Disease at the Time of Transplantation: A Retrospective Cohort Study

The ideal conditioning intensity in allogeneic hematopoietic stem cell transplantation (HSCT) is evolving. Previous prospective studies comparing myeloablative conditioning (MAC) versus reduced-intensity conditioning (RIC) regimens in adults with acute myelogenous leukemia (AML) have shown mixed results. In many of these studies, patients were not stratified based on measurable residual disease (MRD). We evaluated the effect of conditioning intensity on the outcomes of AML patients in complete remission (CR) with flow cytometry evidence of MRD negativity. A total of 135 patients age 20 to 75 years with AML in CR1 or CR2 and flow cytometry evidence of MRD negativity who underwent allogeneic HSCT at our center between 2011 and 2019 were evaluated. We compared overall survival (OS), relapse-free survival (RFS), nonrelapse mortality (NRM), relapse, and acute and chronic graft-versus-host disease (GVHD) in recipients of MAC (n = 89) and RIC (n = 46). Although the patients receiving RIC were older (62 versus 51 years; P < .0001), there were no statistically significant differences between the groups in terms of Eastern Cooperative Oncology Group and European Leukemia Network risk criteria and disease status (CR1 or CR2) at the time of transplantation. At a median follow-up of 24.6 months, no statistically significant differences in OS (hazard ratio [HR], 0.78; 95% confidence interval [CI] 0.42 to 1.42, P = .411) or RFS (HR, 1.004; 95% CI, 0.48 to 2.09, P = .99) were identified. The cumulative incidence of NRM (HR, 0.595; 95% CI, 0.24 to 1.48; P = .2644) and relapse (HR, 1.007; 95% CI, 0.45 to 2.23; P = .9872) was not different between the 2 groups. Grade II-IV and grade III-IV acute GVHD were more frequent in the MAC group (39.3% verses 19.9% [P = .018] and 19.3% versus 2.3% [P < .001], respectively), as was moderate/severe chronic GVHD (23.6% versus 15.8%; P = .038). Our data indicate that conditioning intensity did not appear to affect OS, RFS, NRM, and relapse risk in patients with MRD-negative AML as measured by flow cytometry. RIC resulted in less severe acute and chronic GVHD.

Reduced-intensity versus Myeloablative Conditioning Regimens for Younger Adults with Acute Myeloid Leukemia and Myelodysplastic Syndrome: A systematic review and meta-analysis

Background: Historically, reduced-intensity conditioning (RIC) was recommended to be performed for older patients who were considered ineligible for myeloablative conditioning (MAC) before allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the evidence regarding the optimal conditioning intensity in younger patients with AML or MDS is weak and contradictory.

Methods: PubMed, Medline, Embase, and other online sources were searched from the initial period to February 25, 2020. Odds ratios and 95% confidence intervals were calculated to estimate pooling effects.

Results: Four randomized controlled trials (RCTs) about conditioning intensity involving 633 patients were included. There were no significant differences of 1/2/4/5 years progression-free survival (PFS) and relapse incidence (RI) between two conditioning intensities. Overall survival (OS) was similar at 1/2/4 years, but patients receiving RIC had a higher OS at 5 years. Additionally, RIC were associated with lower non-relapse mortality, less grade II-IV and grade III-IV acute graft-versus-host disease (GVHD), and lower incidence of chronic GVHD compared with MAC regimens. Subgroup analysis showed similar OS and RI for AML patients, and there was a trend towards lower NRM and grade II-IV aGVHD in RIC group. Available data for MDS indicated that OS, PFS, and RI were comparable. For intermediate-risk patients, there was no evidence that RIC is inferior to MAC. However, for high-risk patients, MAC tends to perform better.

Conclusions: Based on the above results, it might be concluded that RIC is a feasible treatment option for adults with AML or MDS younger than 66 years, particularly those with intermediate-risk disease. Future RCTs incorporating of risk stratifications are warranted to guide the optimal decision under certain conditions.

Extra-medullary recurrence of myeloid leukemia as myeloid sarcoma after allogeneic stem cell transplantation: impact of conditioning intensity

Myeloid sarcoma (MS) as a solid extra-medullary (EM) manifestation of acute myeloid leukemia (AML), myeloproliferative or myelodysplastic syndromes is a rare presentation of relapse after allogeneic hematopoietic stem cell transplantation (HSCT). The databases of the Departments of Hematology and Oncology of the University Hospitals of Jena and Rostock were screened for patients aged 18 years or older for onset of MS after HSCT for myeloid malignancies between 2002 and 2019. Nineteen patients with MS were identified, the majority of whom had received reduced-intensity conditioning (RIC). The median onset of MS was 425 days after HSCT and the median overall survival since MS was 234 days. Although MS is associated with a poor prognosis, three patients survived more than two years and one more than 11 years after MS onset. These results indicate that RIC protocols may be associated with a higher risk of EM relapse. Since EM relapse occurred in the presence of Graft-versus-host-disease, these observations also demonstrate the limitations of graft-versus-tumor effects after HSCT. In conclusion, occurrence of MS after HSCT is associated with a poor prognosis, as multimodal curative concepts including intensive chemotherapy and another HSCT are often not viable.

Reduced Intensity Conditioning Allogeneic Hematopoietic Stem Cell Transplantation for Acute Lymphoblastic Leukemia; Current Evidence, and Improving Outcomes Going Forward

PURPOSE OF REVIEW

Outcomes for older adults with acute lymphoblastic leukemia (ALL) remain poor, and allogeneic hematopoietic stem cell transplant (HSCT) remains a potentially curative modality. However, benefits are offset by high rates of non-relapse mortality (NRM) in patients undergoing myeloablative conditioning (MAC) regimens. Reduced intensity conditioning (RIC) regimens can extend this therapy to adults who are unfit for MAC, although at the cost of higher relapse rates. In this review, we discuss evidence to support the usage of RIC regimens, controversies, and potential strategies to improve transplant outcomes going forward.

RECENT FINDINGS

Several novel therapies have recently been approved for the treatment of relapsed ALL and may play an important role in bridging adults with residual disease to RIC transplant. Assessing response to initial therapy via minimal residual disease (MRD) monitoring may determine which patients will derive the most benefit from allogeneic HSCT. Reduced intensity allogeneic HSCT remains a potentially curative therapy that can be offered to older adults however challenges remain. Going forward, MRD testing and novel therapies may help better select which patients should proceed to transplant and assist in getting those patients to transplant with optimally controlled disease.

Comparison of reduced-intensity and myeloablative conditioning regimens for allogeneic hematopoietic stem cell transplantation in patients with acute myeloid leukemia and acute lymphoblastic leukemia: a meta-analysis

Currently, the indications to perform reduced-intensity conditioning allogeneic hematopoietic stem cell transplant (RIC-HCT) are based on data derived mainly from large registry and single-centre retrospective studies. Thus, at the present time, there is limited direct evidence supporting the current practice in selecting patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) for RIC versus myeloablative conditioning (MAC) transplants. To determine the relationship between dose intensity of conditioning regimen and survival outcomes after allografting in AML/ALL patients, we performed a meta-analysis of 23 clinical trials reported between 1990 and 2013 involving 15,258 adult patients that compare survival outcomes after RIC-HCT versus MAC-HCT. RIC-HCT resulted in comparable <2-year and 2-6 year overall survival (OS) rates post-transplantation even though the RIC-HCT recipients were older and had more active disease than MAC-HCT recipients. The 2-6 year progression-free survival (PFS), nonrelapse mortality, acute graft-versus-host disease (GvHD) and chronic GvHD rates were reduced after RIC-HCT, but relapse rate was increased. Similar outcomes were observed regardless of disease type and status at transplantation. Odds ratio for all outcomes remained comparable with or without performing separate analyses for the year of HCT and for retrospective versus prospective studies. Among RIC-HCT recipients, survival rates were superior if patients were in CR at transplantation. Significant inter-study heterogeneity for aGvHD data and publication bias for PFS data were observed. This meta-analysis showed no OS benefit of MAC-HCT over RIC-HCT across the entire cohort of patients suggesting that RIC-HCT could be an effective therapeutic option for AML/ALL patients who are ineligible for MAC-HCT and CR status is preferred before RIC-HCT.

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.

Evidence for a GVL effect following reduced-intensity allo-SCT in ALL: a British Society of Blood and Marrow Transplantation study

Myeloablative allo-SCT decreases relapse incidence (RI) in ALL. Reduced intensity conditioning (RIC) may extend allo-SCT to older and less fit patients. Sixty-nine ALL patients reported to the BSBMT underwent fludarabine-based RIC allo-SCT, 38 from unrelated donors (UD). Forty-four patients received alemtuzumab. ALL was in CR in 64 patients (93%). This was a second or third SCT in 23 patients. Two-year OS and PFS were 36% and 32%, respectively. In multivariate analysis male recipients demonstrated better OS and PFS (hazard ratio (HR) = 0.42, P = 0.008 and HR = 0.45, P = 0.012, respectively). Two-year TRM was 29%: higher with younger age (HR = 0.97/year, P = 0.041), female recipient (HR = 2.55, P = 0.049) and increasing grade of acute GVHD (HR = 1.87, P = 0.001). Two-year RI was 38% and was lower in patients with acute and chronic GVHD (HR = 0.62 per increasing grade, P = 0.035 and HR = 0.52, P = 0.025, respectively). Long-term ALL-free survival is achievable following fludarabine-based RIC allo-SCT. The association between GVHD and decreased RI suggests the presence of a GVL effect.

The second therapeutic trial for children with hematological malignancies who relapsed after their first allogeneic SCT: long-term outcomes

The impact of a second all-SCT on the long-term outcomes of children who relapse after allo-SCT has been unclear. We retrospectively analyzed the long-term outcomes of different salvage treatments for such children. Sixty-six children with hematological malignancies (40 ALL, 22 AML, three MDS, and one CML) who relapsed after a first allo-SCT received either a second allo-SCT (n = 16) or CTx and/or DLI (n = 50). The median follow-up for all children was 9.1 yr. The five-yr OS after relapse was significantly better in patients who underwent a second allo-SCT (42.9%) than in patients treated with CTx and/or DLI (11.8%) (p < 0.05). However, this advantage diminished with increasing time. The eight-yr OS for these groups of patients were 21.4% and 11.8%, respectively (p = n.s.). Among the 16 patients who received a second allo-SCT, two died more than five yr after the second allo-SCT. A second allo-SCT can therefore lead to a prolonged OS in patients who relapse after allo-SCT. However, a second allo-SCT should be selected carefully. This is because the mortality rate is still high, even when there is an extensive duration of time following the second allo-SCT.

Similar outcomes using myeloablative vs reduced-intensity allogeneic transplant preparative regimens for AML or MDS

Although reduced intensity (RIC) and nonmyeloablative (NMA) conditioning regimens have been used for over a decade, their relative efficacy versus myeloablative (MA) approaches to allogeneic hematopoietic cell transplantation (HCT) in patients with acute myelogenous leukemia (AML) and myelodysplasia (MDS) is unknown. We compared disease status, donor, graft and recipient characteristics with outcomes of 3731 MA with 1448 RIC/NMA procedures performed at 217 centers between 1997 and 2004. Five year univariate probabilities and multivariate relative risk (RR) outcomes of relapse, transplant related mortality (TRM), disease free survival (DFS) and overall survival (OS) are reported. Adjusted OS at 5 years was 34%, 33%, and 26% for MA, RIC and NMA transplants, respectively. NMA conditioning resulted in inferior DFS and OS but there was no difference in DFS and OS between RIC and MA regimens. Late TRM negates early decreases in toxicity with RIC and NMA regimens. Our data suggest higher regimen intensity may contribute to optimal survival in patients with AML/MDS, suggesting roles for both regimen intensity and graft vs. leukemia in these diseases. Prospective studies comparing regimens are needed to confirm this finding and determine the optimal approach to patients who are eligible for either MA or RIC/NMA conditioning.

Allogeneic immunotherapy to optimize the graft-versus-tumor effect: concepts and controversies

This article focuses on the recent evolution of novel conditioning regimens in combination with adoptive cellular therapy in the allogeneic transplant setting for hematologic malignancies. Building on data from animal models, the field of allogeneic transplantation is undergoing a paradigm shift toward immunosuppressive regimens with less toxicity that allow donor hematopoietic engraftment in order to provide a graft-versus-tumor effect as the primary goal of transplantation, rather than chemoablation. In addition, the strategies described in this article, including the use of T-cell subsets as adoptive therapy, will apply to a much broader pool of patients than traditional transplant approaches, thereby allowing more patients with life-limiting illnesses, previously deemed ineligible, to pursue therapy with curative intent.

Comparison of reduced intensity and myeloablative conditioning regimens for stem cell transplantation in patients with malignancies: a meta-analysis

OBJECTIVE

The reduced intensity conditioning (RIC) stem cell transplantation is widely employed for the treatment of many hematologic malignancies, but the survival effectiveness is still unclear. This study conducted an updated meta-analysis to determine whether any significant difference could be found by using RIC vs. myeloablative conditioning (MAC) regimen for transplantation in patients with malignancies.

METHODS

We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and relevant articles (1987.01-2009.12). Comparative studies were carried out on clinical therapeutic effect of RIC and MAC on the survival outcomes and the transplantation-related complications.

RESULTS

We obtained 1776 records, and 29 studies totaling 6235 patients have been assessed. Compared with MAC regimen, the RIC regimen had a higher overall survival (OS) at one-yr and no difference at two-yr later after transplantation. RIC regimen had significantly lower rates of disease-free survival (DFS) after two-yr follow-up, lower incidences of ≥ II degree acute graft-versus-host disease (aGVHD), and lower TRM [OR, 0.61, 95% CI (0.53, 0.69)], but with a higher relapse rate [OR, 1.88(1.41, 2.51)]. No significant difference was found in rates of cytomegalovirus (CMV) infection and chronic GVHD between the regimens.

CONCLUSIONS

This meta-analysis confirmed that compared with MAC condition regimen, the RIC regimen had a consistently equivalent or even better rate in OS, but with lower DFS at longer follow-up.

Allogeneic hematopoietic cell transplantation for adults with acute myeloid leukemia: myths, controversies, and unknowns

Progress in the last decade has improved the understanding of leukemia biology. Molecular markers in combinations with cytogenetics have improved the risk stratification of acute myeloid leukemia (AML) and informed decision-making. In parallel, several important advances in the transplant field, such as better supportive care, improved transplant technology, increased availability of alternative donors, and reduced-intensity conditioning have improved the safety as well as access of allogeneic hematopoietic cell transplantation (HCT) for a larger number of patients. In this review, the positioning of HCT in the management of patients with AML is evaluated in view of changing risk/benefit ratios associated with both conventional treatments and transplantation, and some of the controversies are addressed in light of emerging data. Increasing data demonstrate outcomes of alternative donor transplantation approaching HLA-identical sibling donors in high-risk AML supporting the inclusion of alternative donors in trials of prospective studies evaluating post remission strategies for high-risk AML. The use of reduced-intensity conditioning has expanded the eligibility of HCT to older patients with AML, and outcome data are encouraging. Continued study of HCT versus alternative therapies is required to optimize patients' outcomes in AML.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on the Epidemiology and Natural History of Relapse following Allogeneic Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is increasingly being used for treatment of hematologic malignancies, and the immunologic graft-versus-tumor effect (GVT) provides its therapeutic effectiveness. Disease relapse remains a cause of treatment failure in a significant proportion of patients undergoing alloHSCT without improvements over the last 2-3 decades. We summarize here current data and outline future research regarding the epidemiology, risk factors, and outcomes of relapse after alloHSCT. Although some factors (eg, disease status at alloHSCT or graft-versus-host disease [GVHD] effects) are common, other disease-specific factors may be unique. The impact of reduced-intensity regimens on relapse and survival still need to be assessed using contemporary supportive care and comparable patient populations. The outcome of patients relapsing after an alloHSCT generally remains poor even though interventions including donor leukocyte infusions can benefit some patients. Trials examining targeted therapies along with improved safety of alloHSCT may result in improved outcomes, yet selection bias necessitates prospective assessment to gauge the real contribution of any new therapies. Ongoing chronic GVHD (cGVHD) or other residual post-alloHSCT morbidities may limit the applicability of new therapies. Developing strategies to promptly identify patients as alloHSCT candidates, while malignancy is in a more treatable stage, could decrease relapses rates after alloHSCT. Better understanding and monitoring of minimal residual disease posttransplant could lead to novel preemptive treatments of relapse. Analyses of larger cohorts through multicenter collaborations or registries remain essential to probe questions not amenable to single center or prospective studies. Studies need to provide data with detail on disease status, prior treatments, biologic markers, and posttransplant events. Stringent statistical methods to study relapse remain an important area of research. The opportunities for improvement in prevention and management of post-alloHSCT relapse are apparent, but clinical discipline in their careful study remains important.

The outcome of full-intensity and reduced-intensity conditioning matched sibling or unrelated donor transplantation in adults with Philadelphia chromosome-negative acute lymphoblastic leukemia in first and second complete remission

We examined the efficacy of reduced-intensity conditioning (RIC) and compared outcomes of 93 patients older than 16 years after RIC with 1428 patients receiving full-intensity conditioning for allografts using sibling and unrelated donors for Philadelphia-negative acute lymphoblastic leukemia (ALL) in first or second complete remission. RIC conditioning included busulfan 9 mg/kg or less (27), melphalan 150 mg/m(2) or less (23), low-dose total body irradiation (TBI; 36), and others (7). The RIC group was older (median 45 vs 28 years, P < .001) and more received peripheral blood grafts (73% vs 43%, P < .001) but had similar other prognostic factors. The RIC versus full-intensity conditioning groups had slightly, but not significantly, less acute grade II-IV graft-versus-host disease (39% vs 46%) and chronic graft-versus-host disease (34% vs 42%), yet similar transplantation-related mortality. RIC led to slightly more relapse (35% vs 26%, P = .08) yet similar age-adjusted survival (38% vs 43%, P = .39). Multivariate analysis showed that conditioning intensity did not affect transplantation-related mortality (P = .92) or relapse risk (P = .14). Multivariate analysis demonstrated significantly improved overall survival with: Karnofsky performance status more than 80, first complete remission, lower white blood count, well-matched unrelated or sibling donors, transplantation since 2001, age younger than 30 years, and conditioning with TBI, but no independent impact of conditioning intensity. RIC merits further investigation in prospective trials of adult ALL.

Adult acute lymphoblastic leukemia: concepts and strategies

Acute lymphoblastic leukemia (ALL), a clonal expansion of hematopoietic blasts, is a highly heterogeneous disease comprising many entities for which distinct treatment strategies are pursued. Although ALL is a success story in pediatric oncology, results in adults lag behind those in children. An expansion of new drugs, more reliable immunologic and molecular techniques for the assessment of minimal residual disease, and efforts at more precise risk stratification are generating new aspects of adult ALL therapy. For this review, the authors summarized pertinent and recent literature on ALL biology and therapy, and they discuss current strategies and potential implications of novel approaches to the management of adult ALL. Cancer 2010. (c) 2010 American Cancer Society.

Reduced intensity conditioning prior to allogeneic stem cell transplantation in first complete remission is effective in patients with acute myeloid leukemia and an intermediate-risk karyotype

To evaluate the efficacy of reduced intensity conditioning (RIC) prior to allogeneic stem cell transplantation (alloSCT) in patients with acute myeloid leukemia (AML) in first complete remission (CR1), we retrospectively analyzed the outcome of 93 consecutive patients transplanted at our institution either following RIC (n = 37) or standard myeloablative conditioning (MAC) (n = 56) between 1999 and 2007. Projected overall survival (OS) or disease-free survival (DFS) for all patients at 1, 2, and 5 years was 78 or 70%, 65 or 57%, and 61 or 53% in the RIC group versus 73 or 70%, 68 or 62%, and 56 or 54% in the standard MAC group. In the subgroup of patients with an intermediate-risk karyotype projected OS at 1, 2, and 5 years was 86, 68, and 68% following RIC (n = 21) or 75, 69, and 66% following standard MAC (n = 36). Relapse or treatment-related mortality (TRM) was 15 or 17% (RIC group) and 26 or 14% (standard MAC group). Taken together, these data suggest that RIC-alloSCT may induce stable remissions in patients with AML transplanted in CR1. In particular, patients with an intermediate-risk karyotype ineligible to transplantation following standard MAC may benefit from RIC-alloSCT in CR1 at a low TRM.

Ineffective vaccination against solid tumors can be enhanced by hematopoietic cell transplantation

Vaccination with tumor Ags has not been an effective treatment for solid tumors. The goal of the current study was to determine whether a combination of vaccination and hematopoietic cell transplantation (HCT) can effectively treat primary, disseminated, or metastatic CT26 and MC38 murine colon tumors. Vaccination of tumor-bearing mice with irradiated tumor cells and CpG adjuvant failed to alter progressive tumor growth. However, mice bearing primary, disseminated lung, or metastatic liver tumors were uniformly cured after administration of total body irradiation, followed by the transplantation of hematopoietic progenitor cells and T cells from syngeneic, but not allogeneic vaccinated donors. Requirements for effective treatment of tumors included irradiation of hosts, vaccination of donors with both tumor cells and CpG, transfer of both CD4(+) and CD8(+) T cells along with progenitor cells, and ability of donor cells to produce IFN-gamma. Irradiation markedly increased the infiltration of donor T cells into the tumors, and the combined irradiation and HCT altered the balance of tumor-infiltrating cells to favor CD8(+) effector memory T cells as compared with CD4(+)CD25(+)FoxP3(+) T regulatory cells. The combination of vaccination and autologous hematopoietic cell transplantation was also effective in treating tumors. In conclusion, these findings show that otherwise ineffective vaccination to solid nonhematologic tumors can be dramatically enhanced by HCT.

Myeloablative irradiation in non-human primates

PURPOSE

We used total body irradiation (TBI) as conditioning for cord blood transplantation studies in pigtailed macaques. In these studies, different doses of TBI were explored to obtain optimal myelosuppression with acceptable radiation-related side effects.

METHODS

Four macaques received TBI ranging from 800 to 1320 cGy, followed by standard post-transplant care. Hematopoietic recovery was monitored by CBC and donor contribution by variable number of tandem repeats analysis.

RESULTS

Animals receiving 800 or 1020 cGy TBI tolerated the irradiation well with autologous recovery of neutrophils within 24 days. At a dose of 1200 cGy, neither autologous recovery nor extramedullary toxicity was observed. A fourth animal received 1320 cGy of TBI and suffered significant toxicity necessitating termination of the study.

CONCLUSIONS

We conclude that previously considered myeloablative doses of TBI allowed for autologous recovery in the pigtailed macaque, and that a dose of 1200 cGy may be most appropriate, providing both myeloablation and acceptable non-hematopoietic toxicities.

Vascular endothelium as 'novel' target of graft-versus-host disease

There is increasing evidence of the existence of an endothelial form of graft-versus-host disease (GvHD). The early endothelial injury syndromes - transplant-associated microangiopathy (TAM), veno-occlusive disease (VOD) of the liver, diffuse alveolar hemorrhage, engraftment syndrome, and capillary leak syndrome - all share common features with acute GvHD. They are more likely to occur after allogeneic hematopoietic stem-cell transplantation (HCT), in unrelated transplantation, or with non-T-cell-depleted grafts. In addition, acute GvHD is a risk factor for all these endothelial syndromes. Chronic GvHD leads to a rarefaction of microvessels caused by the infiltration of alloreactive cytotoxic T lymphocytes. Furthermore, late cardiovascular accidents are more likely to occur in patients treated with allogeneic than autologous HCT, suggesting that an immunological mechanism is involved in the development of atherosclerosis. Finally, biomarkers of endothelial injury show a close relationship with GvHD. These data support the notion that early endothelial damage syndromes, atherosclerosis, and vascular endothelial GvHD share a common denominator in patients treated with allogeneic HCT.

Allogeneic SCT in refractory or relapsed adult ALL is effective without prior reinduction chemotherapy

We present 60 patients with refractory (n=8) or relapsed (n=52) adult ALL who received allogeneic hematopoietic SCT (HSCT) with (n=41) or without (n=19) prior reinduction chemotherapy. In our center, omission of reinduction is recommended if a suitable donor is promptly available, tumor burden is moderate and disease features suggest a highly aggressive course. Overall survival (OS) of the whole cohort at 1, 2 and 5 years was 42, 33 and 28%, respectively. Leukemia-free survival at 1, 2 and 5 years was 37, 33 and 24%. Deaths were due to relapse (n=25), acute or chronic GVHD (n=7), infections (n=8) or toxicity (n=4). Interestingly, patients who did not receive reinduction before HSCT had better outcomes than patients who received reinduction with OS at 1, 2 and 5 years being 58 vs 34%, 47 vs 25% and 47 vs 18%, respectively (P=0.039). Importantly, even achievement of a second CR after reinduction was not associated with improved survival compared to patients directly proceeding to HSCT. We conclude that patients who undergo HSCT for refractory or relapsed ALL can achieve long-term survival. In selected patients, reinduction chemotherapy can be omitted if immediate HSCT is feasible.

Unrelated donor transplants in adults with Philadelphia-negative acute lymphoblastic leukemia in first complete remission

We report the retrospective outcomes of unrelated donor (URD) transplants in 169 patients with acute lymphoblastic leukemia (ALL) in first complete remission (CR1) who received transplants between 1995 and 2004. Median age was 33 years (range, 16-59 years). A total of 50% had a white blood cell count (WBC) more than 30 x 10(9)/L, 18% extramedullary disease, 42% achieved CR more than 8 weeks from diagnosis, 25% had adverse cytogenetics, and 19% had T-cell leukemia. A total of 41% were HLA well-matched, 41% partially matched with their donors, and 18% were HLA-mismatched. At 54-month median follow-up, incidences of acute grade 2-IV, III to IV, and chronic graft-versus-host disease were 50%, 25%, and 43%, respectively. Five-year treatment-related mortality (TRM), relapse, and overall survival were 42%, 20%, and 39%, respectively. In multivariate analyses, TRM was significantly higher with HLA-mismatched donors and T-cell depletion. Relapse risk was higher if the diagnostic WBC was more than 100 x 10(9)/L. Factors associated with poorer survival included WBC more than 100 x 10(9)/L, more than 8 weeks to CR1, cytomegalovirus seropositivity, HLA mismatching, and T-cell depletion. Nearly 40% of adults with ALL in CR1 survive 5 years after URD transplantation. Relapse risks were modest; TRM is the major cause of treatment failure. Selecting closely HLA-matched URD and reducing TRM should improve results.

Allogeneic hematopoietic stem-cell transplantation for myeloid sarcoma: a retrospective study from the SFGM-TC

PURPOSE

This retrospective multicenter study assessed the outcome of 51 patients with myeloid sarcoma (MS) who underwent allogeneic hematopoietic stem-cell transplantation (alloHSCT).

PATIENTS AND METHODS

Most patients had MS presenting in conjunction with acute myeloid leukemia (AML) or after AML. Six patients had isolated MS. The median time between diagnosis and alloHSCT was 8 months (range, 2.8 to 67). Forty patients were in complete remission (CR) at time of alloHSCT.

RESULTS

With a median follow-up of 33 (range, 1 to 182) months, the Kaplan-Meier estimates of overall survival (OS) and disease-free survival were 47% (95% CI, 33% to 61%) and 36% (95% CI, 24% to 50%) at 5 years. Twenty patients (39%) relapsed at a median of 204 (range, 35 to 1151) days after alloHSCT, with relapse being the major cause of death. In a Cox multivariate analysis, age > or = 15 years and remission status at time of alloHSCT (CR v other) were associated with improved OS (hazard ratio [HR], 0.27; 95% CI, 0.12 to 0.65; P = .003; and HR, 0.22; 95% CI, 0.08 to 0.57; P = .002, respectively).

CONCLUSION

We conclude that first-line alloHSCT performed early in the course of MS is a valid therapeutic option.

Allogeneic hematopoietic stem cell transplantation in the elderly

The development of reduced intensity or non-myeloablative conditioning (NST) in preparation for allogeneic stem cell transplantation (SCT) revolutionized the field and led to reconsideration of the dogma of upper age limit that was set up by the transplant centers as an eligibility parameter. Analysis of the literature data showed that NST regimens are associated with decreased transplant related mortality, and graft-versus-host disease, in comparison with standard myeloablative conditioning, in patients above the age of 50-55 years, or in younger patients with significant comorbidities. However we have to mention, that our considerations are based on the retrospective analysis of the literature data, and that well controlled prospective randomized studies are needed in order to definitely assess the role of NST. Comorbidity indices might be proved as the most important parameters for the choice of the most proper regimen for each patient in need and should be included in future trials.

Hematopoietic stem cell therapy for malignant diseases

Allogeneic bone marrow or blood stem cell transplantation (SCT) has changed its face in the last two decades. The introduction of nonmyeloablative conditioning regimens has reduced procedure toxicity and allowed the application of SCT in patients and conditions in which SCT was not offered in the past. In this review we will summarize the changes and accomplishments achieved in the past years in the field of stem cell transplantation for malignant disorders.

Treatment of Relapsed Acute Leukemia after Allogeneic Transplantation: A Single Center Experience

Relapsed acute leukemia after allogeneic transplantation has a poor prognosis and most reports have focused on the role of second transplantations in relapsed patients. We report our single-institution experience on the management of relapsed acute leukemia after allogeneic transplantation. We aimed to describe the outcome of relapsed acute leukemia after allogeneic transplantation at our institution and investigate whether maneuvers intended to augment donor T cell allogeneic reactivity were associated with durable graft-versus-leukemia effects. We analyzed 310 patients with acute leukemia who received allogeneic hematopoietic progenitor cell transplants from HLA-matched donors between 1982 and 2005 (229 with acute myelogenous leukemia, 81 with acute lymphoblastic leukemia). Mean post-transplant follow-up was 5 years (range, 0.5-22 years). Factors associated with relapse incidence, therapy for relapse, response to treatment, and post-relapse survival were assessed. One hundred of 310 patients (32%) with acute leukemia relapsed after transplantation, including 28 of 81 patients (35%) with acute lymphoblastic leukemia and 72 of 229 (31%) with acute myelogenous leukemia at a median of 136 days after transplantation. Median post-relapse survival periods were 51 days for the 69 patients who received chemotherapy/supportive care, 84 days for 11 recipients of donor lymphocyte infusions, 303 days for 13 recipients of second transplants, and 442 days for 7 patients treated with interferon-alpha and granulocyte-macrophage colony-stimulating factor. A multivariable Cox regression analysis indicated that a longer time to relapse after transplantation, peripheral blood as source of stem cells, and initial post-relapse therapy with cytokines, donor lymphocyte infusions, or second transplants were associated with improved post-relapse survival (P <.001, <.001, and .025). The outlook for patients with post-transplant relapse of acute leukemia is extremely poor; currently, no single therapy consistently results in durable remissions. Our study highlights the need for clinical trials in this area. Therapy with granulocyte-macrophage colony stimulating factor and interferon-alpha-2b is promising and will be pursued in a prospective trial at our center.

Strategies to enhance immune function in hematopoietic transplantation recipients who have fungal infections

The challenges in the treatment of systemic fungal infections after HSCT include: (1) changing epidemiology as less drug-susceptible saprophytic fungi are increasingly associated with human disease; (2) the difficulty of early and correct diagnosis, even with the new generation of enzymatic immunoassays; (3) the inability to reduce or eliminate predisposing factors, especially severe immune suppression in most transplant patients with these infections and (4) the uncertain role of antifungal drug combinations and risk of drug antagonism complicating effective empiric-pre-emptive therapy. Current, developing and future immune enhancement strategies including recombinant granulocyte- and granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-gamma (IFN-gamma), adjuvant pro-inflammatory cytokine therapy during mobilized donor granulocyte transfusions, therapeutic potential of pentraxin, adaptive immune transfer and dendritic cell fungal vaccines. Improved understanding of the molecular pathogenesis of fungal infections and of the complexity of host antifungal immune responses has provided the critical information to readdress existing treatment paradigms and further evaluate the role of GM-CSF and IFN-gamma early in the course of therapy against life-threatening fungal infections in high-risk patients following stem cell transplantation.

Fludarabine phosphate and melphalan: a reduced intensity conditioning regimen suitable for allogeneic transplantation that maintains the graft versus malignancy effect

Reduced intensity conditioning (RIC) for allogeneic stem cell transplantation allows stable donor cell engraftment with the maintenance of a graft versus malignancy effect. Many different regimens exist employing various combinations of chemotherapy, radiotherapy and T-cell depletion. We examined the role of non-T-cell depleted RIC regimens in 56 patients with haematological malignancies. Patients received fludarabine phosphate for 5 days (30 mg/m2 in 35 patients, 25 mg/m2 in 21 patients) and melphalan for 1 day (140 mg/m2 in 36 patients, 100 mg/m2 in 20 patients). Immunosuppression was with CyA alone in 33 patients and CyA/MTX in 23 patients. Twenty-four of the 26 patients with chimerism data showed >95% donor chimerism at 3 months post transplant. aGVHD occurred in 18% of patients receiving CyA/MTX compared to 53% of patients receiving CyA. The 100-day mortality rate was 0.16 (95%CI 0.08-0.28) and 1-year nonrelapse mortality was 0.24 (95%CI 0.13-0.38). Thirty-three patients remained alive and in CR at a median of 19 months post transplant (range 3-38 months). We have shown that patients transplanted with fludarabine phosphate, melphalan 100 mg/m2 and with CyA/MTX as post transplant immunosuppression can achieve good disease control with an acceptable level of toxicity. Further studies are required to confirm these findings.