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

Review of allogeneic hematopoietic stem cell transplantation with reduced intensity conditioning in solid tumors excluding breast cancer

Solid tumors in adults constitute a heterogeneous group of malignancy originating from various organ systems. Solid tumors are not completely curable by chemotherapy, even though some subgroups are very chemo-sensitive. Recently, oncologists have focused on the use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) with reduced intensity conditioning (RIC) for the treatment of some refractory solid tumors. After the demonstration of allogeneic graft-versus-leukemia effect in patients with hematological malignancies who received allo-HSCT, investigators evaluated this effect in patients with refractory metastatic solid tumors. According to data from experimental animal models and preliminary clinical trials, a graft-versus-tumor (GvT) effect may also be observed in the treatment of some solid tumors (e.g., renal cell cancer, colorectal cancer, etc.) after allo-HSCT with RIC. The use of RIC regimens offers an opportunity of achieving full-donor engraftment with GvT effect, as well as, a reduced transplant-related mortality. Current literature suggests that allo-HSCT with RIC might become a choice for elderly and medically fragile patients with refractory metastatic solid tumors.

Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics of Immunosuppressants in Allogeneic Hematopoietic Cell Transplantation: Part II

Part I of this article included a pertinent review of allogeneic hematopoietic cell transplantation (alloHCT), the role of postgraft immunosuppression in alloHCT, and the pharmacokinetics, pharmacodynamics, and pharmacogenomics of the calcineurin inhibitors and methotrexate. In this article (Part II), we review the pharmacokinetics, pharmacodynamics, and pharmacogenomics of mycophenolic acid (MPA), sirolimus, and the antithymocyte globulins (ATG). We then discuss target concentration intervention (TCI) of these postgraft immunosuppressants in alloHCT patients, with a focus on current evidence for TCI and on how TCI may improve clinical management in these patients. Currently, TCI using trough concentrations is conducted for sirolimus in alloHCT patients. Several studies demonstrate that MPA plasma exposure is associated with clinical outcomes, with an increasing number of alloHCT patients needing TCI of MPA. Compared with MPA, there are fewer pharmacokinetic/dynamic studies of rabbit ATG and horse ATG in alloHCT patients. Future pharmacokinetic/dynamic research of postgraft immunosuppressants should include '-omics'-based tools: pharmacogenomics may be used to gain an improved understanding of the covariates influencing pharmacokinetics as well as proteomics and metabolomics as novel methods to elucidate pharmacodynamic responses.

Pharmacokinetics, Pharmacodynamics and Pharmacogenomics of Immunosuppressants in Allogeneic Haematopoietic Cell Transplantation: Part I

Although immunosuppressive treatments and target concentration intervention (TCI) have significantly contributed to the success of allogeneic haematopoietic cell transplantation (alloHCT), there is currently no consensus on the best immunosuppressive strategies. Compared with solid organ transplantation, alloHCT is unique because of the potential for bidirectional reactions (i.e. host-versus-graft and graft-versus-host). Postgraft immunosuppression typically includes a calcineurin inhibitor (cyclosporine or tacrolimus) and a short course of methotrexate after high-dose myeloablative conditioning, or a calcineurin inhibitor and mycophenolate mofetil after reduced-intensity conditioning. There are evolving roles for the antithymyocyte globulins (ATGs) and sirolimus as postgraft immunosuppression. A review of the pharmacokinetics and TCI of the main postgraft immunosuppressants is presented in this two-part review. All immunosuppressants are characterized by large intra- and interindividual pharmacokinetic variability and by narrow therapeutic indices. It is essential to understand immunosuppressants' pharmacokinetic properties and how to use them for individualized treatment incorporating TCI to improve outcomes. TCI, which is mandatory for the calcineurin inhibitors and sirolimus, has become an integral part of postgraft immunosuppression. TCI is usually based on trough concentration monitoring, but other approaches include measurement of the area under the concentration-time curve (AUC) over the dosing interval or limited sampling schedules with maximum a posteriori Bayesian personalization approaches. Interpretation of pharmacodynamic results is hindered by the prevalence of studies enrolling only a small number of patients, variability in the allogeneic graft source and variability in postgraft immunosuppression. Given the curative potential of alloHCT, the pharmacodynamics of these immunosuppressants deserves to be explored in depth. Development of sophisticated systems pharmacology models and improved TCI tools are needed to accurately evaluate patients' exposure to drugs in general and to immunosuppressants in particular. Sequential studies, first without and then with TCI, should be conducted to validate the clinical benefit of TCI in homogenous populations; randomized trials are not feasible, because there are higher-priority research questions in alloHCT. In Part I of this article, we review the alloHCT process to facilitate optimal design of pharmacokinetic and pharmacodynamics studies. We also review the pharmacokinetics and TCI of calcineurin inhibitors and methotrexate.

Relevance of prognostic factors in the decision-making of stem cell transplantation in Myelodysplastic Syndromes

The hematopoietic stem cell transplantation (HSCT) is the only curative alternative for Myelodysplastic Syndrome (MDS), but many patients are not eligible for this treatment, as there are several limiting factors, especially in the case of patients with low-risk MDS. The aim of this study is to discuss the factors that can guide the decision-making on referring or not a patient to HSCT. Three cases of MDS, two of which were submitted to HSCT are presented. We intend to report the difficulties in referring patients with MDS to transplant and the prognostic factors that contribute to define eligibility.

Anti-thymocyte globulin as graft-versus-host disease prevention in the setting of allogeneic peripheral blood stem cell transplantation: a review from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic hematopoietic stem cell transplantation is increasingly used as treatment for patients with life-threatening blood diseases. Its curative potential is largely based on immune-mediated graft-versus-leukemia effects caused by donor T cells contained in the graft. Unfortunately, donor T cells are also the cause of graft-versus-host disease. The vast majority of human leukocyte antigen-matched allogeneic hematopoietic stem cell transplants are nowadays carried out with peripheral blood stem cells as the stem cell source. In comparison with bone marrows, peripheral blood stem cells contain more hematopoietic stem/progenitor cells but also one log more T cells. Consequently, the use of peripheral blood stem cells instead of bone marrow has been associated with faster hematologic recovery and a lower risk of relapse in patients with advanced disease, but also with a higher incidence of chronic graft-versus-host disease. These observations have been the basis for several studies aimed at assessing the impact of immunoregulation with anti-thymocyte globulin on transplantation outcomes in patients given human leukocyte antigen-matched peripheral blood stem cells from related or unrelated donors. After a brief introduction on anti-thymocyte globulin, this article reviews recent studies assessing the impact of anti-thymocyte globulin on transplantation outcomes in patients given peripheral blood stem cells from human leukocyte antigen-matched related or unrelated donors as well as in recipients of grafts from human leukocyte antigen haploidentical donors.

Efficacy of host-dendritic cell vaccinations with or without minor histocompatibility antigen loading, combined with donor lymphocyte infusion in multiple myeloma patients

Donor lymphocyte infusions (DLI) can induce durable remissions in multiple myeloma (MM) patients, but this occurs rather infrequently. As the graft-versus-tumor (GvT) effect of DLI depends on the presence of host-dendritic cells (DCs), we tested in a phase I/II trial whether the efficacy of DLI could be improved by simultaneous vaccination with host-DCs. We also analyzed the possibility of further improving the GvT effect by loading the DCs with peptides of mismatched hematopoietic cell-specific minor histocompatibility antigens (mHags). Fifteen MM patients not responding to a first DLI were included. Eleven patients could be treated with a second equivalent dose DLI combined with DC vaccinations, generated from host monocytes (moDC). For four patients, the DC products did not meet the quality criteria. In four of the treated patients the DCs were loaded with host mHag peptides. Toxicity was limited and no acute GvHD occurred. Most patients developed objective anti-host T-cell responses and in one patient a distinct mHag-specific T-cell response accompanied a temporary clinical response. These findings confirm that DLI combined with host-DC vaccination, either unloaded or loaded with mHag peptides, is feasible, safe and capable of inducing host-specific T-cell responses. The limited clinical effects may be improved by developing more immunogenic DC products or by combining this therapy with immune potentiating modalities like checkpoint inhibitors.

Role of reduced-intensity conditioning allogeneic hematopoietic cell transplantation in older patients with de novo acute myeloid leukemia

Reduced-intensity conditioning (RIC) regimens extend the therapeutic use of allogeneic hematopoietic cell transplantation (HCT) to older patients. The survival trend in 2325 patients aged >50 years presenting with de novo acute myeloid leukemia (AML) who underwent first reduced-intensity HCT (RIC-HCT) was assessed by retrospectively analyzing outcomes between 2000 and 2013. The annual number of RIC-HCTs in Japan was higher in the 2008-2013 period (n = 205/year [1229/6 years]) than in the 2000-2007 period (n = 137/year [1096/8 years]). Overall and disease-free survival were higher in the 2008-2013 period (P < 0.001) because of the improvement in transplant-related mortality (TRM). Survival regarding RIC-HCT for AML has improved over time, with an increased number of RIC-HCTs in patients with a Karnofsky performance status (KPS) ≥80. However, TRM remains high and the relapse rate has not improved over time. Multivariate analyses showed that a KPS ≥80 and complete remission at HCT were associated with less TRM and relapse, and better survival regardless of age ≥65 years. Accurate timing and prospective identification of patients at risk of TRM may aid the development of risk-adapted strategies for RIC-HCT in AML patients regardless of age.

Milestones of Hematopoietic Stem Cell Transplantation - From First Human Studies to Current Developments

Since the early beginnings, in the 1950s, hematopoietic stem cell transplantation (HSCT) has become an established curative treatment for an increasing number of patients with life-threatening hematological, oncological, hereditary, and immunological diseases. This has become possible due to worldwide efforts of preclinical and clinical research focusing on issues of transplant immunology, reduction of transplant-associated morbidity, and mortality and efficient malignant disease eradication. The latter has been accomplished by potent graft-versus-leukemia (GvL) effector cells contained in the stem cell graft. Exciting insights into the genetics of the human leukocyte antigen (HLA) system allowed improved donor selection, including HLA-identical related and unrelated donors. Besides bone marrow, other stem cell sources like granulocyte-colony stimulating-mobilized peripheral blood stem cells and cord blood stem cells have been established in clinical routine. Use of reduced-intensity or non-myeloablative conditioning regimens has been associated with a marked reduction of non-hematological toxicities and eventually, non-relapse mortality allowing older patients and individuals with comorbidities to undergo allogeneic HSCT and to benefit from GvL or antitumor effects. Whereas in the early years, malignant disease eradication by high-dose chemotherapy or radiotherapy was the ultimate goal; nowadays, allogeneic HSCT has been recognized as cellular immunotherapy relying prominently on immune mechanisms and to a lesser extent on non-specific direct cellular toxicity. This chapter will summarize the key milestones of HSCT and introduce current developments.

Unrelated donor versus matched sibling donor in adults with acute myeloid leukemia in first relapse: an ALWP-EBMT study

Background

Allogeneic stem cell transplantation is the only curative option for patients with acute myeloid leukemia (AML) experiencing relapse. Either matched sibling donor (MSD) or unrelated donor (UD) is indicated.

Methods

We analyzed 1554 adults with AML transplanted from MSD (n = 961) or UD (n = 593, HLA-matched 10/10, n = 481; 9/10, n = 112). Compared to MSD, UD recipients were older (49 vs 52 years, p = 0.001), transplanted more recently (2009 vs 2006, p = 0.001), and with a longer interval to transplant (10 vs 9 months, p = 0.001). Conditioning regimen was more frequently myeloablative for patients transplanted with a MSD (61 vs 46 %, p = 0.001). Median follow-up was 28 (range 3–157) months.

Results

Cumulative incidence (CI) of neutrophil engraftment (p = 0.07), grades II–IV acute GVHD (p = 0.11), chronic GVHD (p = 0.9), and non-relapse mortality (NRM, p = 0.24) was not different according to the type of donor. At 2 years, CI of relapse (relapse incidence (RI)) was 57 vs 49 % (p = 0.001). Leukemia-free survival (LFS) at 2 years was 21 vs 26 % (p = 0.001), and overall survival (OS) was 26 vs 33 % (p = 0.004) for MSD vs UD, respectively. Chronic GVHD as time-dependent variable was associated with lower RI (HR 0.78, p = 0.05), higher NRM (HR 1.71, p = 0.001), and higher OS (HR 0.69, p = 0.001). According to HLA match, RI was 57 vs 50 vs 45 %, (p = 0.001) NRM was 23 vs 23 vs 29 % (p = 0.26), and LFS at 2 years was 21 vs 27 vs 25 % (p = 0.003) for MSD, 10/10, and 9/10 UD, respectively. In multivariate analysis adjusted for differences between the two groups, UD was associated with lower RI (HR 0.76, p = 0.001) and higher LFS (HR 0.83, p = 0.001) compared to MSD. Interval between diagnosis and transplant was the other factor associated with better outcomes (RI (HR 0.62, p < 0.001) and LFS (HR 0.67, p < 0.001)).

Conclusions

Transplantation using UD was associated with better LFS and lower RI compared to MSD for high-risk patients with AML transplanted in first relapse.

The impact of HLA-matching on reduced intensity conditioning regimen unrelated donor allogeneic stem cell transplantation for acute myeloid leukemia in patients above 50 years-a report from the EBMT acute leukemia working party

Background

Data comparing fully matched and mismatched-unrelated-donor (M- and mM-URD) allogeneic hematopoietic stem cell transplant (allo-SCT) following reduced intensity conditioning regimens for acute myeloid leukemia are limited.

Methods

We retrospectively compared the outcome of 3398 patients above the age of 50 years who underwent 10/10 M-URD (n = 2567), 9/10 (n = 723), or 8/10 (n = 108) mM-URD allo-SCT for acute myeloid leukemia after reduced intensity conditioning regimen between 2000 and 2013. The Kaplan-Meier estimator, the cumulative incidence function, and Cox proportional hazards regression models were used where appropriate.

Results

HLA matching had no impact on engraftment (p = 0.31). In univariate analysis, in comparison to 10/10 M-URD, mM-URD was associated with higher incidence of grade II–IV acute graft-versus-host disease (GVHD) (p = 0.0002), similar rates of chronic GVHD (p = 0.138) but increased incidence of its extensive form (p = 0.047). Compared to 10/10 M-URD, patients transplanted in the first complete remission (CR1) with a 9 or an 8/10 mM-URD had decreased 2-year leukemia free (LFS) (p = 0.005) and overall survivals (OS) (56.7, 46.1, and 50.2 %, respectively, p = 0.005), while outcomes were comparable between all groups for patients transplanted beyond CR1. In multivariate analysis, 9/10 versus 10/10 URD was associated with higher non-relapse mortality (HR 1.34, p = 0.001), similar risk of relapse and chronic GVHD and inferior LFS (HR 1.25, p = 0.0001), and OS (HR 1.27, p = 0.0001). There was no difference in adjusted transplant outcomes between 9/10 and 8/10 mM-URD.

Conclusions

Reduced intensity conditioned allo-SCT with a 10/10 M-URD remains the preferable option for AML patients above the age of 50 years. The use of a 9/10 or an 8/10 mM-URD in patients not having a fully matched donor represents an alternative therapeutic option that should be compared to other alternative donor transplant strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0295-9) contains supplementary material, which is available to authorized users.

Matched unrelated donor transplants-State of the art in the 21st century

Hematopoietic stem cell transplantation (HSCT) is the therapy of choice in many hematological malignant and non-malignant diseases by using human leukocyte antigen (HLA)-matched siblings as stem cell source but only one third of the patients will have HLA-matched siblings. Hence, physicians rely on the availability of matched unrelated donors (URD). The possibility of finding a matched URD is now more than 70% due to continuous expansion of URD registries around the world. The use of URD in adult patients is steadily increasing and in the last 8 years has superseded the numbers of matched sibling donor transplants and has become the most commonly used stem cell source. There is also an increasing trend to use peripheral blood (PB) stem cells rather than bone marrow (BM) stem cells. Outcomes following URD transplants depend mainly upon the indication and urgency of transplant, age and comorbidities of recipients, cytomegalovirus (CMV) matching/mismatching between donor and the recipient, and degree of HLA matching. In some studies outcome of unrelated stem cell transplants in terms of treatment-related mortality (TRM), disease-free survival (DFS), and overall survival (OS) is comparable to sibling donors.

Comparable Allogeneic Hematopoietic Cell Transplantation Outcome of a Haplo-Identical Family Donor with an Alternative Donor in Adult Aplastic Anemia

We performed a study on allogeneic hematopoietic cell transplantation (alloHCT) from an HLA-haplo-identical familial donor (haploFD) using a busulfan-fludarabine-antithymocyte globulin conditioning regimen for severe aplastic anemia (sAA) and hypoplastic myelodysplastic syndrome. For the comparison between a haploFD and an alternative donor (AD; matched unrelated or partially matched donor) for sAA in adults, we collected haploFD data retrospectively and prospectively. Forty-eight AD cases were selected for the comparison with 16 haploFD cases. All transplantation outcomes except for extensive chronic graft versus host disease (GvHD) were similar. The frequencies of hepatic sinusoidal obstruction syndrome (p = 1.000), acute GvHD (p = 0.769), grade 3/4 acute GvHD (p = 0.258), chronic GvHD (p = 0.173), extensive chronic GvHD (p = 0.099), primary neutrophil engraftment failure (p = 1.000), secondary graft failure (p = 1.000) and platelet engraftment failure (p = 0.505) were similar. Time to neutrophil engraftment was faster in haploFD (p = 0.003), while the cumulative incidence of platelet engraftment was similar (p = 0.505). Overall survival was also similar between AD and haploFD (p = 0.730). In conclusion, alloHCT from haploFD in sAA was comparable with alloHCT from AD, but extensive chronic GvHD seemed frequent in haploFD. Therefore alloHCT from haploFD could be an alternative approach for alloHCT from AD in adult sAA.

Reduced-Intensity Conditioning with Fludarabine, Cyclophosphamide, and Rituximab Is Associated with Improved Outcomes Compared with Fludarabine and Busulfan after Allogeneic Stem Cell Transplantation for B Cell Malignancies

Reduced-intensity conditioning (RIC) has been used increasingly for allogeneic hematopoietic cell transplantation to minimize transplant-related mortality while maintaining the graft-versus-tumor effect. In B cell lymphoid malignancies, reduced-intensity regimens containing rituximab, an antiCD20 antibody, have been associated with favorable survival; however, the long-term outcomes of rituximab-containing versus nonrituximab-containing regimens for allogeneic hematopoietic cell transplantation in B cell lymphoid malignancies remain to be determined. We retrospectively analyzed 94 patients who received an allogeneic transplant for a B cell lymphoid malignancy. Of these, 33 received RIC with fludarabine, cyclophosphamide, and rituximab (FCR) and graft-versus-host disease (GVHD) prophylaxis with a calcineurin inhibitor and mini-methotrexate, and 61 received RIC with fludarabine and busulfan (FluBu) and GVHD prophylaxis with a calcineurin inhibitor and mycophenolate mofetil. The 2-year overall survival was superior in patients who received FCR versus FluBu (72.7% versus 54.1%, P = .031), and in multivariable analysis adjusted for Disease Risk Index and donor type, only the conditioning regimen (FluBu versus FCR: HR, 2.06; 95% CI, 1.04 to 4.08; P = .037) and Disease Risk Index (low versus intermediate/high: HR, .38; 95% CI, .17 to .86; P = .02) were independent predictors of overall survival. The 2-year cumulative incidence of chronic GVHD was lower in patients who received FCR versus FluBu (24.2% versus 51.7%, P = .01). There was no difference in rate of relapse/progression or acute GVHD. Our results demonstrate that the use of RIC with FCR and GVHD prophylaxis with a calcineurin inhibitor and mini-methotrexate is associated with decreased chronic GVHD and improved overall survival.

Targeted Cancer Therapy Using Radiolabeled Monoclonal Antibodies

Radioimmunotherapy (RIT) combines the advantages of targeted radiation therapy and specific immunotherapy using monoclonal antibodies. RIT can be used either to target tumor cells or to specifically suppress immunocompetent host cells in the setting of allogeneic transplantation. The choice of radionuclide used for RIT depends on its distinct radiation characteristics and the type of malignancy or cells targeted. Beta-emitters with their lower energy and longer path length are more suitable to target bulky, solid tumors whereas α-emitters with their high linear energy transfer and short path length are better suited to target hematopoietic cells (normal or malignant). Different approaches of RIT such as the use of stable radioimmunoconjugates or of pretargeting strategies are available. Encouraging results have been obtained with RIT in patients with hematologic malignancies. The results in solid tumors are somewhat less favorable but new strategies for patients with minimal residual disease using adjuvant and locoregional treatment are evolving. This report outlines basic principles of RIT, gives an overview of available radionuclides and radioimmunoconjugates, and discusses clinical results with special emphasis on their use in hematologic malignancies including use in conditioning regimens for bone marrow transplantation.

Optimal graft source for allogeneic hematopoietic stem cell transplant: bone marrow or peripheral blood?

Peripheral blood (PB), compared with bone marrow graft, has higher stem cell content, leads to faster engraftment and is more convenient for collection. Consequently, the use of PB graft has significantly increased in recent years. Although the use of PB graft is acceptable or even preferred to bone marrow graft in matched related donor allogeneic transplant due to a possibility of improved survival, PB graft increases the risk of chronic graft-versus-host disease and associated long-term toxicities in the setting of matched unrelated donor allogeneic transplant. In haploidentical transplant, mitigation of graft-versus-host disease with the use of post-transplant cyclophosphamide is a hypothesis-generating possibility; however, available studies have significant limitations to draw any definite conclusion.

Fludarabine-Busulfan Reduced-Intensity Conditioning in Comparison with Fludarabine-Melphalan Is Associated with Increased Relapse Risk In Spite of Pharmacokinetic Dosing

Fludarabine with busulfan (FB) and fludarabine with melphalan (FM) are commonly used reduced-intensity conditioning (RIC) regimens. Pharmacokinetic dosing of busulfan (Bu) is frequently done for myeloablative conditioning, but evidence for its use is limited in RIC transplants. We compared transplant outcomes of FB versus FM using i.v. Bu targeted to the area under the curve (AUC). A total of 134 RIC transplants (47 FB and 87 FM) for acute myelogenous leukemia and myelodysplastic syndrome were identified, and median follow-up of the cohort was 40 months (range, 0 to 63.3). A significantly higher 2-year cumulative incidence of relapse (CIR) was associated with FB versus FM at 35.6% versus 17.3%, respectively (P = .0058). Furthermore, 2-year progression-free survival rates were higher for FM versus FB at 60.5% versus 48.7%, respectively (P = .04). However, 2-year rates of nonrelapse mortality (NRM) and overall survival (OS) were similar. The need for dose adjustment based on AUC did not alter relapse risk or NRM. Patients with Karnofsky performance status ≥ 90 who received FM had a 2-year OS rate of 74.8% versus 48.3% for FB (P = .03). FB use remained prognostic for relapse in multivariable analysis (hazard ratio, 2.75; 95% confidence interval, 1.28 to 5.89; P = .0097). In summary, in spite of AUC-directed dosing, FB compared with FM was associated with a significantly higher CIR.

Kinetics of Langerhans cell chimerism in the skin of dogs following 2 Gy TBI allogeneic hematopoietic stem cell transplantation

Background

Langerhans cells (LC) are bone marrow-derived cells in the skin. The LC donor/recipient chimerism is assumed to influence the incidence and severity of graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT). In nonmyeloablative (NM) HSCT the appearance of acute GVHD is delayed when compared with myeloablative conditioning. Therefore, we examined the development of LC chimerism in a NM canine HSCT model.

Methods

2 Gy conditioned dogs received bone marrow from dog leukocyte antigen identical littermates. Skin biopsies were obtained pre- and post-transplant. LC isolation was performed by immunomagnetic separation and chimerism analysis by PCR analyzing variable-number-of-tandem-repeat markers with subsequent capillary electrophoresis.

Results

All dogs engrafted. Compared to peripheral blood chimerism the development of LC chimerism was delayed (earliest at day +56). None of the dogs achieved complete donor LC chimerism, although two dogs manifested a 100 % donor chimerism in peripheral blood at days +91 and +77. Of interest, one dog remained LC chimeric despite loss of donor chimerism in the peripheral blood cells.

Conclusion

Our study indicates that LC donor chimerism correlates with chimerism development in the peripheral blood but occurs delayed following NM-HSCT.

Choice of Unmanipulated T Cell Replete Graft for Haploidentical Stem Cell Transplant and Posttransplant Cyclophosphamide in Hematologic Malignancies in Adults: Peripheral Blood or Bone Marrow-Review of Published Literature

Allogeneic hematopoietic stem cell transplantation (SCT) is often the only curative option for many patients with malignant and benign hematological stem cell disorders. However, some issues are still of concern regarding finding a donor like shrinking family sizes in many societies, underrepresentation of the ethnic minorities in the registries, genetic variability for some races, and significant delays in obtaining stem cells after starting the search. So there is a considerable need to develop alternate donor stem cell sources. The rapid and near universal availability of the haploidentical donor is an advantage of the haploidentical SCT and an opportunity that is being explored currently in many centers especially using T cell replete graft and posttransplant cyclophosphamide. This is probably because it does not require expertise in graft manipulation and because of the lower costs. However, there are still lots of unanswered questions, like the effect of use of bone marrow versus peripheral blood as the source of stem cells on graft-versus-host disease, graft versus tumor, overall survival, immune reconstitution, and quality of life. Here we review the available publications on bone marrow and peripheral blood experience in the haploidentical SCT setting.

Toxicity and efficacy of busulfan and fludarabine myeloablative conditioning for HLA-identical sibling allogeneic hematopoietic cell transplantation in AML and MDS

The safety and efficacy of a 4-day myeloablative conditioning (MAC) regimen consisting of Bu 3.2 mg/kg and fludarabine 40 mg/m(2)/day for HLA-identical sibling allogeneic hematopoietic cell transplantation (HCT) in myeloid malignancies was investigated in 133 patients (median age, 47 years; range 19-74 years) with de novo AML (60%), secondary AML (20%) or myelodysplastic syndrome (20%). All patients engrafted. Hepatic veno-occlusive disease occurred in five patients (4%), and severe toxicities, mostly mucositis, occurred in twenty-three (17%) patients. The non-relapse mortality (NRM) at 100 days was 1.5%. The incidences of acute GVHD grade 2-4 and grade 3-4 were 32 and 13%, respectively. At a median follow-up of 38 months, the cumulative incidence of chronic GVHD was 67%. The relapse incidence was 30% (27 and 31%, respectively, in patients with early- and late-stage disease), and the overall NRM was 15%. The actuarial 4-year disease-free survival (DFS) and overall survival (OS) were 54 and 62%, respectively. Patients aged <50 years had better outcomes compared with older patients (DFS 64 vs 42%, P=0.006; OS 73 vs 47%, P<0.001, respectively).

The safety of treatment options for elderly people with acute myeloid leukemia

INTRODUCTION

Life expectancy in elderly patients with acute myeloid leukemia (AML) is a function of age, disability, and co-morbidity, combined with leukemia characteristics. There is currently no consensus regarding the optimal therapeutic strategy for older adults with AML. Although selected older adults with AML can benefit from intensive therapies, recent evidence supports the use of lower-intensity therapies in most patients and emphasizes the importance of tolerability and quality of life.

AREAS COVERED

Results of the current clinical trials and safety data are reviewed.

EXPERT OPINION

Treatment recommendations for elderly patients with AML need to be individualized. In order to avoid toxicities, hematologists should collaborate more with geriatricians to identify clues of vulnerability in elderly patients through the study of functional physical, physiological, cognitive, social, and psychological parameters.

The efficacy and safety of a new reduced-toxicity conditioning with 4 days of once-daily 100 mg/m(2) intravenous busulfan associated with fludarabine and antithymocyte globulins prior to allogeneic stem cell transplantation in patients with high-risk myelodysplastic syndrome or acute leukemia

The optimal intensity of myeloablation associated with a reduced-toxicity conditioning (RTC) regimen in order to decrease the relapse rate without increasing non-relapse mortality (NRM), is not well established yet. This retrospective analysis was done on 30 patients with hematological malignancies. The aim was to assess the safety of a RTC regimen based on the busulfan at a dose of 100 mg/m(2)/d intravenously for 4 d, fludarabine at a dose of 30 mg/m(2)/d for 5 d, and anti-thymoglobulins at a dose of 2.5 mg/kg/d for 2 d. The cumulative incidences of grade 2-4 acute graft-versus-host disease (GVHD) and all grades chronic GVHD were 37% and 42%, respectively. Median 1-year overall survival and disease-free survival were 66% and 50%, respectively. At 1 year, the cumulative incidence of relapse/disease progression was 33%. NRM was 3% and 17% at day 100 and 1 year, respectively. This RTC conditioning regimen can lead to a long-term disease control. Moreover, it appears to be safe with a low NRM rate among high-risk patients.

Reduced intensity conditioning allogeneic hematopoietic cell transplantation for adult acute myeloid leukemia in complete remission - a review from the Acute Leukemia Working Party of the EBMT

Acute myeloid leukemia is the most common indication for an allogeneic hematopoietic cell transplant. The introduction of reduced intensity conditioning has expanded the recipient pool for transplantation, which has importantly made transplant an option for the more commonly affected older age groups. Reduced intensity conditioning allogeneic transplantation is currently the standard of care for patients with intermediate or high-risk acute myeloid leukemia and is now most often employed in older patients and those with medical comorbidities. Despite being curative for a significant proportion of patients, post-transplant relapse remains a challenge in the reduced intensity conditioning setting. Herein we discuss the studies that demonstrate the feasibility of reduced intensity conditioning allogeneic transplants, compare the outcomes of reduced intensity conditioning versus chemotherapy and conventional myeloablative conditioning regimens, describe the optimal donor and stem cell source, and consider the impact of post-remission consolidation, comorbidities, center experience, and more intensive (reduced toxicity conditioning) regimens on outcomes. Additionally, we discuss the need for further prospective studies to optimize transplant outcomes.

Addition of 10-Day Decitabine to Fludarabine/Total Body Irradiation Conditioning is Feasible and Induces Tumor-Associated Antigen-Specific T Cell Responses

Allogeneic hematopoietic cell transplantation (HCT) offers the possibility of curative therapy for patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myelogenous leukemia (AML). However, post-HCT relapse remains a major problem, particularly in patients with high-risk cytogenetics and in patients who cannot tolerate consolidation chemotherapy (eg, due to previous toxicity). We assessed the toxicity and efficacy of 10-day decitabine (Dec), fludarabine (Flu), and 2 Gy total body irradiation (TBI) as a new conditioning regimen for allogeneic HCT in patients with MDS, CMML, or AML. Thirty patients were enrolled, including 11 with MDS, 2 with CMML, and 17 with AML. Patients received 20 mg/m(2)/day Dec on days -11 to -2, 30 mg/m(2)/day Flu on days -4 to -2, and 2 Gy TBI on day -1, followed by infusion of a donor stem cell graft on day 0. Postgrafting immunosuppression consisted of cyclosporin A and mycophenolate mofetil. At a median follow-up of 443 days, the overall survival was 53%, relapse incidence was 27%, and nonrelapse mortality was 27%. The incidence of severe acute (grade III/IV) graft-versus-host disease (GVHD) was 27%, and that of (predominantly mild) chronic GVHD was 60%. Immunomonitoring studies revealed that specific CD8(+) T cell responses against epigenetically silenced tumor-associated antigens (TAAs), including cancer-testis antigens (MAGE-A1/A2/A3 and PRAME) and RHAMM, occurred more frequently in patients who had received Dec/Flu/TBI conditioning (8 of 11 patients) compared with a control group of patients who had received only Flu/TBI conditioning (2 of 9 patients). In summary, Dec/Flu/TBI conditioning proved feasible and effective and enhanced the induction of TAA-reactive CD8(+) T cell responses in vivo, which may contribute to disease control post-transplantation.

Use of hematopoietic cell transplants to achieve tolerance in patients with solid organ transplants

The goals of tolerance in patients with solid organ transplants are to eliminate the lifelong need for immunosuppressive (IS) drugs and to prevent graft loss due to rejection or drug toxicity. Tolerance with complete withdrawal of IS drugs has been achieved in recipients of HLA-matched and mismatched living donor kidney transplants in 3 medical centers using hematopoietic cell transplants to establish mixed or complete chimerism.

Haploidentical bone marrow and stem cell transplantation: experience with post-transplantation cyclophosphamide

Allogeneic blood or bone marrow transplantation (BMT) is a potentially curative therapy for high-risk hematologic malignancies not curable by standard chemotherapy, but the procedure is limited by the availability of human leukocyte antigen-matched donors for many patients, as well as toxicities including graft-versus-host disease (GVHD). Our group has developed the use of high-dose post-transplantation cyclophosphamide (PTCy) to selectively remove alloreactive T cells without compromising engraftment. This protocol has allowed for successful transplantation of human leukocyte antigen (HLA)-haploidentical (haplo) grafts, thus expanding the donor pool for the many patients who would not otherwise be a candidate for this life-saving procedure. In this review we will summarize the data that led to the development of PTCy, then focus on the outcomes of haploBMT trials with PTCy across different transplant platforms for patients with malignant hematologic diseases, and finally we will discuss emerging evidence that suggests equivalency of haploBMT with PTCy compared with more traditional transplants.

Hematopoietic stem cell transplantation for patients with AML in first complete remission

Postremission therapy in patients with acute myeloid leukemia (AML) may consist of continuing chemotherapy or transplantation using either autologous or allogeneic stem cells. Patients with favorable subtypes of AML generally receive chemotherapeutic consolidation, although recent studies have also suggested favorable outcome after hematopoietic stem cell transplantation (HSCT). Although allogeneic HSCT (alloHSCT) is considered the preferred type of postremission therapy in poor- and very-poor-risk AML, the place of alloHSCT in intermediate-risk AML is being debated, and autologous HSCT is considered a valuable alternative that may be preferred in patients without minimal residual disease after induction chemotherapy. Here, we review postremission transplantation strategies using either autologous or allogeneic stem cells. Recent developments in the field of alternative donors, including cord blood and haploidentical donors, are highlighted, and we discuss reduced-intensity alloHSCT in older AML recipients who represent the predominant category of patients with AML who have a high risk of relapse in first remission.

Adoptive cellular therapy: a race to the finish line

Adoptive T cell transfer for cancer, chronic infection, and autoimmunity is an emerging field that shows promise in recent trials. Using the principles of synthetic biology, advances in cell culture and genetic engineering have made it possible to generate human T cells that display desired specificities and enhanced functionalities compared with the natural immune system. The prospects for widespread availability of engineered T cells have changed dramatically, given the recent entry of the pharmaceutical industry to this arena. Here, we discuss some of the challenges--such as regulatory, cost, and manufacturing--and opportunities, including personalized gene-modified T cells, that face the field of adoptive cellular therapy.

Role of Chemotherapy and Allografting in the Treatment of Acute Lymphoblastic Leukemia

We report the clinical outcomes of 83 patients with acute lymphoblastic leukemia (median age, 46 years; range, 18-75 years) treated at our institution between 1999 and 2011. Treatment refers to clinical trials open for accrual at the time of diagnosis or to institutional guidelines. Upfront allografting was considered for younger high-risk patients. Seventy-eight of 83 (94%) patients achieved complete remission after induction, although 53% of them eventually relapsed. Forty of 70 patients younger than 61 years underwent allografting. The median follow-up was 7.4 years (range, 0.2-15.0 years). Overall, the 5-year overall survival (OS) and event-free survival (EFS) were 40% and 39%, respectively. In patients undergoing transplantation, OS and EFS at 5 years were both 53%, whereas in a nontransplantation setting, both OS and EFS were 35% at 5 years (P = .044 for both OS and EFS). By multivariate analysis, the independent predictors of OS and EFS were age and leukocytosis in the overall population and allografting in young patients.

Long-Term Follow-Up of Allogeneic Hematopoietic Stem Cell Transplantation for Solid Cancer

We wanted to determine whether allogeneic hematopoietic stem cell transplantation (HSCT) may result in long-term survival in patients with solid cancer. HSCT was performed in 61 patients with solid cancer: metastatic renal carcinoma (n = 22), cholangiocarcinoma (n = 17), colon carcinoma (n = 15), prostate cancer (n = 3), pancreatic adenocarcinoma (n = 3), or breast cancer (n = 1). Liver transplantation was performed for tumor debulking in 18 patients. Median age was 56 years (range, 28 to 77). Donors were either HLA-identical siblings (n = 29) or unrelated (n = 32). Conditioning was nonmyeloablative (n = 23), reduced (n = 36), or myeloablative (n = 2). Graft failure occurred in 13 patients (21%). The cumulative incidence of acute graft-versus-host disease (GVHD) of grades II to IV was 47%, and that of chronic GVHD was 32%. Treatment-related mortality was 21%. At 5 years cancer-related mortality was 63%. Currently, 6 patients are alive, 2 with renal cell carcinoma, 1 with cholangiocarcinoma, and 3 with pancreatic carcinoma. Eight-year survival was 12%. Risk factors for mortality were nonmyeloablative conditioning (HR, 2.95; P < .001), absence of chronic GVHD (HR, 3.57; P < .001), acute GVHD of grades II to IV (HR, 2.90; P = .002), and HLA-identical transplant (HR, 5.00; P = .03). With none of these risk factors, survival at 6 years was 50% (n = 6). Long-term survival can be achieved in some patients with solid cancer after HSCT.

Comparable outcome after single-antigen-mismatched versus matched unrelated donor haematopoietic cell transplantation

PURPOSE

Allogeneic haematopoietic stem cell transplantation (HSCT) is a proven treatment for patients with haematological malignancies. In this retrospective analysis, the impact of donor matching on outcome of unrelated HSCT was analysed in patients transplanted at the University of Leipzig.

METHODS

From 2000 to 2009, 206 patients were transplanted from unrelated donors, of which 51 were mismatched (39 in 1 and 12 in ≥ 2 HLA-antigens), using peripheral blood or bone marrow grafts after total body irradiation and cyclophosphamide or busulfan and cyclophosphamide preparative regimens in combination with ATG. For graft-versus-host disease (GvHD) prophylaxis cyclosporine and MTX were administered.

RESULTS

After a median follow-up of 49 months, outcome at 5 years in recipients of HLA-identical grafts was comparable to that of patients transplanted from HLA-incompatible donors with an overall survival (OS) of 52 % (95 % CI 43-61) versus 48 % (95 % CI 34-63), respectively (p = 0.48). Results were also comparable for event-free survival at 5 years [47 % (95 % CI 38-56) vs. 39 % (95 % CI 25-54); p = 0.44], relapse incidence (RI) [29 % (95 % CI 20-38) vs. 41 (95 % CI 25-57); p = 0.22] and non-relapse mortality [24 % (95 % CI 16-33) vs. 20 % (95 % CI 8-33); p = 0.84] in the matched versus mismatched groups. Incidence of acute and chronic GvHD was similar in both groups. Advanced disease (p = 0.02) and low-resolution typing (p = 0.04) are risk factors for OS and RI in univariate and multivariate analysis.

CONCLUSIONS

Donors with one antigen mismatch are an acceptable option for patients with malignant disease for whom no fully matched donor is available.

Phase II Study of Allogeneic Transplantation for Older Patients With Acute Myeloid Leukemia in First Complete Remission Using a Reduced-Intensity Conditioning Regimen: Results From Cancer and Leukemia Group B 100103 (Alliance for Clinical Trials in Oncology)/Blood and Marrow Transplant Clinical Trial Network 0502

PURPOSE

Long-term survival rates for older patients with newly diagnosed acute myeloid leukemia (AML) are extremely low. Previous observational studies suggest that allogeneic hematopoietic stem-cell transplantation (HSCT) may improve overall survival (OS) because of lower rates of relapse. We sought to prospectively determine the value of HSCT for older patients with AML in first complete remission.

PATIENTS AND METHODS

We conducted a prospective multicenter phase II study to assess the efficacy of reduced-intensity conditioning HSCT for patients between the ages of 60 and 74 years with AML in first complete remission. The primary end point was disease-free survival at 2 years after HSCT. Secondary end points included nonrelapse mortality (NRM), graft-versus-host disease (GVHD), relapse, and OS.

RESULTS

In all, 114 patients with a median age of 65 years received transplantations. The majority (52%) received transplantations from unrelated donors and were given antithymocyte globulin for GVHD prophylaxis. Disease-free survival and OS at 2 years after transplantation were 42% (95% CI, 33% to 52%) and 48% (95% CI, 39% to 58%), respectively, for the entire group and 40% (95% CI, 29% to 55%) and 50% (95% CI, 38% to 64%) for the unrelated donor group. NRM at 2 years was 15% (95% CI, 8% to 21%). Grade 2 to 4 acute GVHD occurred in 9.6% (95% CI, 4% to 15%) of patients, and chronic GVHD occurred in 28% (95% CI, 19% to 36%) of patients. The cumulative incidence of relapse at 2 years was 44% (95% CI, 35% to 53%).

CONCLUSION

Reduced-intensity conditioning HSCT to maintain remission in selected older patients with AML is relatively well tolerated and appears to provide superior outcomes when compared with historical patients treated without HSCT. GVHD and NRM rates were lower than expected. Future transplantation studies in these patients should focus on further reducing the risk of relapse.

Minor histocompatibility Ags: identification strategies, clinical results and translational perspectives

Allogeneic stem cell transplantation (allo-SCT) and donor lymphocyte infusion are effective treatment modalities for various hematological malignancies. Their therapeutic effect, the graft-versus-tumor (GvT) effect, is based mainly on an alloimmune response of donor T cells directed at tumor cells, in which differences in the expression of minor histocompatibility Ags (mHags) on the cells of the patient and donor have a crucial role. However, these differences are also responsible for induction of sometimes detrimental GvHD. As relapse and development of GvHD pose major threats for a large proportion of allotransplanted patients, additional therapeutic strategies are required. To augment the GvT response without increasing the risk of GvHD, specific mHag-directed immunotherapeutic strategies have been developed. Over the past years, much effort has been put into the identification of therapeutically relevant mHags to enable these strategies for a substantial proportion of patients. Currently, the concept of mHag-directed immunotherapy is tested in clinical trials on feasibility, safety and efficacy. In this review, we will summarize the recent developments in mHag identification and the clinical data on mHag-specific immune responses and mHag-directed therapies in patients with hematological malignancies. Finally, we will outline the current challenges and future prospectives in the field.

Pushing the envelope-nonmyeloablative and reduced intensity preparative regimens for allogeneic hematopoietic transplantation

Allogeneic hematopoietic cell transplantation (HCT) was originally developed to allow delivery of myeloablative doses of chemotherapy and radiotherapy. With better understanding of disease pathophysiology, the graft vs malignancy (GVM) effect of allogeneic hematopoietic transplantation and toxicities associated with myeloablative conditioning (MAC) regimens, the focus shifted to developing less toxic conditioning regimens to reduce treatment-related morbidity without compromising survival. Although HCT with MAC is preferred to reduced intensity conditioning (RIC) for most patients ⩽60 years with AML/myelodysplastic syndrome and ALL, RIC and nonmyeloablative (NMA) regimens allow HCT for many otherwise ineligible patients. Reduced intensity preparative regimens have produced high rates of PFS for diagnoses, which are highly sensitive to GVM. Relapse of the malignancy is the major cause of treatment failure with RIC/NMA HCT. Incorporation of novel agents like bortezomib or lenalidomide, addition of cellular immunotherapy and use of targeted radiation therapies could further improve outcome. In this review, we discuss commonly used RIC/NMA regimens and promising novel regimens.

The hematopoietic system in the context of regenerative medicine

Hematopoietic stem cells (HSC) represent the prototype stem cell within the body. Since their discovery, HSC have been the focus of intensive research, and have proven invaluable clinically to restore hematopoiesis following inadvertent radiation exposure and following radio/chemotherapy to eliminate hematologic tumors. While they were originally discovered in the bone marrow, HSC can also be isolated from umbilical cord blood and can be "mobilized" peripheral blood, making them readily available in relatively large quantities. While their ability to repopulate the entire hematopoietic system would already guarantee HSC a valuable place in regenerative medicine, the finding that hematopoietic chimerism can induce immunological tolerance to solid organs and correct autoimmune diseases has dramatically broadened their clinical utility. The demonstration that these cells, through a variety of mechanisms, can also promote repair/regeneration of non-hematopoietic tissues as diverse as liver, heart, and brain has further increased their clinical value. The goal of this review is to provide the reader with a brief glimpse into the remarkable potential HSC possess, and to highlight their tremendous value as therapeutics in regenerative medicine.

Janus Kinase Inhibitors and Stem Cell Transplantation in Myelofibrosis

Myelofibrosis (MF) is characterized by splenomegaly, blood count abnormalities, particularly cytopenias, and a propensity for transformation to acute leukemia. The current treatment approach is to ameliorate symptoms due to these abnormalities. Treatment with Janus kinase 2 inhibitors reduces spleen size and improves symptoms in patients with MF, but most of the patients eventually have disease progression and stop responding. Allogeneic stem cell transplantation remains the only curative option. However, its efficacy must be balanced against the risk of treatment-related death and long-term sequelae of transplant like chronic graft versus host disease. The challenge is to integrate treatment with Janus kinase inhibitors with allogeneic stem cell transplantation.

Modeling promising nonmyeloablative conditioning regimens in nonhuman primates

Minimal conditioning or even no conditioning would be the preferred preparation for most gene therapy applications for nonmalignant diseases. However, reduced intensity conditioning (RIC) regimens in patients with nonhematologic malignancies have not led to long-term engraftment unless a selective advantage was present for the transplanted donor cells. Similar findings have also been observed in a number of large animal studies. Inadequate myelosuppression levels were thought to be responsible for the outcomes. To address this issue several innovative protocols in small animals have been presented with selective hematopoietic myelosuppression and less systemic toxicity. Such protocols promised to curb the transplant-related morbidity and mortality in myeloablative conditioning and provide effective long-term engraftment, especially in patients with gene-corrected autografts. In the present study we have tested some of these promising RIC regimens in nonhuman primates, a clinically relevant large animal model. Our data suggest that transient myelosuppression induced by anti-c-Kit antibody in conjunction with low-dose irradiation may lead to long-term engraftment, albeit at low levels. The animals with busulfan conditioning with or without anti-c-Kit that received gene-modified autologous transplants with green fluorescent protein expression had similar myelosuppression, but failed long-term engraftment and despite immunosuppressive treatment had all the hallmarks seen previously in similar models without immunosuppression. Our preliminary data expand current knowledge of RIC and emphasize the need to explore whether specific and directed myelosuppression alone is adequate in the absence of microenvironmental modulation, or whether innovative combinations are necessary for safe and effective engraftment.

Suitability Criteria for Adult Related Donors: A Consensus Statement from the Worldwide Network for Blood and Marrow Transplantation Standing Committee on Donor Issues

The number of allogeneic hematopoietic stem cell (HSC) transplants performed globally each year continues to increase. Advances in HLA typing, better supportive care, and administration of reduced-intensity conditioning regimens allow treatment of older patients with older sibling donors. Pretransplant donor assessment and testing are very important processes affecting the quality and safety of donation. For unrelated HSC donors detailed recommendations for health assessment have been published, allowing donation only if they are unrestrictedly healthy. Eligibility criteria for related donors are less strict and vary significantly between centers. In situations where a family donor does not meet the suitability criteria for unrelated donors, involved physicians often struggle with the decision whether the matched relative is suitable for donation or not. On behalf of the Worldwide Network for Blood and Marrow Transplantation Standing Committee on Donor Issues, we intended to develop a consensus document with recommendations for donor workup and final clearance of family donors who would not be able to serve as unrelated donors because of their age or pre-existing diseases. This article covers different topics intending to support decision-making, with the goal of minimizing medical risk to the donor and protection of the recipient from transmissible diseases.

Clinical Comparison of Non-Myeloablative Conditioning with Anti-Thymocyte Globulin and Fludarabine for Patients with Hematologic Malignancies

Background

The influence of different non-myeloablative conditioning regimens on clinical outcome remains undefined.

Material/Methods

We retrospectively analyzed the hematopoietic reconstitution, graft-versus-host disease (GVHD), and quality of life (QOL) in 56 patients with hematologic malignancies who underwent non-myeloablative stem cell transplantation (NST) with a conditioning regimen based on anti-thymocyte globulin (ATG), followed by donor lymphocyte infusion (n=24), or Fludarabine (FLU) (n=32). Hematopoietic stem cells were derived from low-resolution HLA-matched identical sibling donors.

Results

The blood type transformation and platelet reconstitution presented significantly earlier in the FLU group than the ATG group (P<0.05). Within 100 days post-transplantation, the incidence of grade I–IV acute GVHD was significantly lower in the ATG group than the FLU group (P<0.05). After 100 days post-transplant, extensive chronic GVHD (cGVHD) was more prevalent in the ATG group than the FLU group (P<0.05). There were lower cumulative risk of relapse and higher non-relapse-related mortality in the ATG group, but better QOL in the FLU group within 24 months, and no difference in 3-year disease-free survival (DFS) or overall survival (OS) between the 2 groups (P>0.05).

Conclusions

The FLU-based conditioning regimen improved hematopoietic reconstitution and decreased extensive cGVHD, but there was no difference in 3-year DFS or OS between the 2 groups.

Approaches for the prevention of graft-versus-host disease following hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (HCT) is an important therapeutic option for malignant and non-malignant diseases, but the more widespread application of the therapy remains limited by the occurrence of graft versus host disease (GVHD). GVHD results from immune-mediated injury by donor immune cells against tissues in the HCT recipient, and can be characterized as acute or chronic depending on the time of onset and site of organ involvement. The majority of efforts have focused on GVHD prevention. Calcineurin inhibitors are the most widely used agents and are included in almost all regimens. Despite current prophylaxis strategies, 40-70% of patients remain at risk for developing GVHD. Herein, we review standard and emerging therapies used in GVHD management.

Allogeneic hematopoietic cell transplantation after failed autologous transplant for lymphoma using TLI and anti-thymocyte globulin conditioning

We describe 47 patients with lymphoma and failed prior autologous hematopoietic cell transplantation (HCT) who received TLI-ATG conditioning followed by allogeneic HCT. Thirty-two patients had non-Hodgkin lymphoma (NHL; diffuse large B cell lymphoma [n=19], T-cell NHL [n=6], mantle cell lymphoma [n= 4], or other B-cell subtypes [n=3]), and 15 had Hodgkin lymphoma. The median follow-up was 4.9 (range, 2.1–11.9) years. The cumulative incidence of grade II–IV acute GVHD at day +100 was 12%, and the cumulative incidence of extensive chronic GVHD at 1 year was 36%. The 3-year cumulative incidences of overall survival, progression-free survival (PFS), and non-relapse mortality (NRM) were 81%, 44%, and 7%, respectively. Fifteen patients died (relapse, n=10; NRM, n=5). Among the 25 patients with relapse after allogeneic HCT, 11 (44%) achieved durable (>1 year) complete remissions following donor lymphocyte infusion or chemoradiotherapy. The majority of surviving patients (75%; n=24) were able to discontinue all immunosuppression. For patients with relapsed lymphoma after autologous HCT, allogeneic HCT using TLI-ATG conditioning is a well-tolerated, predominantly outpatient therapy with low NRM (7% at 3 years), a low incidence of GVHD, durable disease control, and excellent overall survival (81% at 3 years).

Impact of irradiation and immunosuppressive agents on immune system homeostasis in rhesus macaques

In this study we examined the effects of non-myeloablative total body irradiation (TBI) in combination with immunosuppressive chemotherapy on immune homeostasis in rhesus macaques. Our results show that the administration of cyclosporin A or tacrolimus without radiotherapy did not result in lymphopenia. The addition of TBI to the regimen resulted in lymphopenia as well as alterations in the memory/naive ratio following reconstitution of lymphocyte populations. Dendritic cell (DC) numbers in whole blood were largely unaffected, while the monocyte population was altered by immunosuppressive treatment. Irradiation also resulted in increased levels of circulating cytokines and chemokines that correlated with T cell proliferative bursts and with the shift towards memory T cells. We also report that anti-thymocyte globulin (ATG) treatment and CD3 immunotoxin administration resulted in a selective and rapid depletion of naive CD4 and CD8 T cells and increased frequency of memory T cells. We also examined the impact of these treatments on reactivation of latent simian varicella virus (SVV) infection as a model of varicella zoster virus (VZV) infection of humans. None of the treatments resulted in overt SVV reactivation; however, select animals had transient increases in SVV-specific T cell responses following immunosuppression, suggestive of subclinical reactivation. Overall, we provide detailed observations into immune modulation by TBI and chemotherapeutic agents in rhesus macaques, an important research model of human disease.

Allogeneic Hematopoietic Stem Cell Transplantation in Mantle Cell Lymphoma: A Retrospective Analysis of 7 Patients

Mantle cell lymphoma (MCL) is a B cell non-Hodgkin's lymphoma characterized by a poor prognosis. Many different therapeutic approaches including intensive chemotherapy as well as new targeted therapies are established. However, overall survival remains unsatisfying. As the sole curative option, allogeneic hematopoietic stem cell transplantation (HSCT) has been described, but only a limited number of patients qualify for this procedure. We have retrospectively analyzed 7 patients with stage IV MCL undergoing allogeneic HSCT at our institution. A myeloablative regimen was used in 1 patient, while the other 6 patients received reduced-intensity conditioning. Four patients had an HLA-identical sibling, and the remaining 3 patients had an HLA-identical unrelated donor. One patient developed acute graft-versus-host disease (skin, grade III; intestine, grade II). Two patients died from transplant-related causes, 3 patients died due to progressive disease and the remaining 2 patients are still in complete remission 147 and 8 months after transplantation. Allogeneic HSCT offers a therapeutic treatment option for selected patients in a relapsed/refractory setting. The incorporation of novel agents has improved the outcome of patients with MCL. Thus, the role and optimal time point of allogeneic HSCT should be reevaluated in randomized trials.

Immune Recovery after Allogeneic Hematopoietic Stem Cell Transplantation Following Flu-TBI versus TLI-ATG Conditioning

PURPOSE

A conditioning regimen for allogeneic hematopoietic cell transplantation (HCT) combining total lymphoid irradiation (TLI) plus anti-thymocyte globulin (ATG) has been developed to induce graft-versus-tumor effects without graft-versus-host disease (GVHD).

EXPERIMENTAL DESIGN

We compared immune recovery in 53 patients included in a phase II randomized study comparing nonmyeloablative HCT following either fludarabine plus 2 Gy total body irradiation (TBI arm, n = 28) or 8 Gy TLI plus ATG (TLI arm, n = 25).

RESULTS

In comparison with TBI patients, TLI patients had a similarly low 6-month incidence of grade II-IV acute GVHD, a lower incidence of moderate/severe chronic GVHD (P = 0.02), a higher incidence of CMV reactivation (P < 0.001), and a higher incidence of relapse (P = 0.01). While recovery of total CD8(+) T cells was similar in the two groups, with median CD8(+) T-cell counts reaching the normal values 40 to 60 days after allo-HCT, TLI patients had lower percentages of naïve CD8 T cells. Median CD4(+) T-cell counts did not reach the lower limit of normal values the first year after allo-HCT in the two groups. Furthermore, CD4(+) T-cell counts were significantly lower in TLI than in TBI patients the first 6 months after transplantation. Interestingly, while median absolute regulatory T-cell (Treg) counts were comparable in TBI and TLI patients, Treg/naïve CD4(+) T-cell ratios were significantly higher in TLI than in TBI patients the 2 first years after transplantation.

CONCLUSIONS

Immune recovery differs substantially between these two conditioning regimens, possibly explaining the different clinical outcomes observed (NCT00603954).

The impact of graft-versus-host disease prophylaxis in reduced-intensity conditioning allogeneic stem cell transplant in acute myeloid leukemia: a study from the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation

The impact of the intensity of graft-versus-host-disease immunoprophylaxis on transplantation outcomes in patients undergoing transplantation following reduced-intensity conditioning is unclear. This study addresses this issue in 228 adult patients above 50 years of age with acute myeloid leukemia in first complete remission given peripheral blood stem cells from HLA-identical siblings after fludarabine and 2 days of intravenous busulfan reduced-intensity conditioning. A total of 152 patients received anti-thymocyte globulin, either in combination with cyclosporine A in 86 patients (group 1), or with cyclosporine A and mycophenolate mofetil or short course methotrexate in 66 patients (group 2). The remaining 76 patients did not receive anti-thymocyte globulin but were given cyclosporine A and methotrexate or mycophenolate mofetil (group 3). Incidences of grade II-IV acute graft-versus-host-disease were comparable in the three groups (16.5%, 29.5% and 19.5% in groups 1, 2 and 3, respectively, P=0.15). In multivariate analysis, the absence of anti-thymocyte globulin was the only factor associated with a higher risk of chronic graft-versus-host-disease (P=0.005), while the use of triple immunosuppression (group 3) was associated with an increased risk of relapse (P=0.003). In comparison to anti-thymocyte globulin and cyclosporine A alone, the other two strategies of graft-versus-host-disease prophylaxis were associated with reduced leukemia-free survival and overall survival (P=0.001 for each parameter), independently of the dose of anti-thymocyte globulin. These data suggest that fine tuning of the intensity of this prophylaxis can affect the outcome of transplantation and that anti-thymocyte globulin and cyclosporine A alone should be the preferred combination with the fludarabine-busulfan reduced-intensity conditioning regimen and sibling donors.

Reduced-intensity conditioned allogeneic SCT in adults with AML

AML is currently the most common indication for reduced-intensity conditioned (RIC) allo-SCT. Reduced-intensity regimens allow a potent GVL response to occur with minimized treatment-related toxicity in patients of older age or with comorbidities that preclude the use of myeloablative conditioning. Whether RIC SCT is appropriate for younger and more standard risk patients is not well defined and the field is changing rapidly; a prospective randomized trial of myeloablative vs RIC (BMT-CTN 0901) was recently closed when early results indicated better outcomes for myeloablative regimens. However, detailed results are not available, and all patients in that study were eligible for myeloablative conditioning. RIC transplants will likely remain the standard of care as many patients with AML are not eligible for myeloablative conditioning. Recent publication of mature results from retrospective and prospective cohorts provide contemporary efficacy and toxicity data for these attenuated regimens. In addition, recent studies explore the use of alternative donors, introduce regimens that attempt to reduce toxicity without reducing intensity, and identify predictive factors that pave the way to personalized approaches. These studies paint a picture of the future of RIC transplants. Here we review the current status of RIC allogeneic SCT in AML.