Reduced-intensity conditioning allogeneic stem cell transplantation for older adults: is it the standard of care? Curr Opin Hematol. 2010;17:133-138. [PMID: 20071984 DOI: 10.1097/moh.0b013e3283366ba4]

Clofarabine and total body irradiation (TBI) as conditioning regimen for allogeneic stem cell transplantation in high-risk acute leukemia patients: a two-center retrospective cohort study

Clofarabine (Clo) is an immunosuppressive purine analog that may have better anti-leukemic activity than fludarabine (Flu). The addition of total body irradiation (TBI) to conditioning regimens has been widely investigated. However, the use of single agent Clo in combination with intermediate doses of TBI ranging from 4 to 8 Gy has not been studied yet. This study is a double center, observational, retrospective study of patients with high-risk hematological malignancies diagnosed from 2012 to 2021, treated at the American University of Beirut Medical Center in Beirut (AUBMC), Lebanon, and Saint-Antoine Hospital (SAH) in Paris, France. It aims to identify the outcome of patients with high-risk hematological malignancies who underwent allogeneic stem cell transplant (allo-SCT) and received Clo and TBI (4-8 Gy) before transplant. Data regarding patient baseline characteristics, disease-related factors, and transplant outcomes including graft-versus-host disease (GVHD), Non-relapse mortality (NRM), progression-free survival (PFS), and overall survival (OS), were collected. We identified 24 high-risk patients diagnosed with a hematological malignancy. The median age at transplant was 37 years (range 22-78). At the time of the transplant, only 15 patients (63%) were in complete remission (CR). All patients received Clo/TBI (4-8 Gy). After a median follow-up of 40 months, the cumulative incidences of grade II-III acute GVHD, grade IV acute GVHD, and chronic GVHD were 50%, 4%, and 8%, respectively. NRM at 100 days, and 1 year after transplant was 4% and 25%, respectively. 17% of the patients had a relapse or progression of the disease by the end of the study. The 2-year PFS and OS were 50% and 56%, respectively. The median PFS and OS were 66 and 68 months respectively. As a conclusion, Clo/TBI (4-8 Gy) as a conditioning regimen for allo-SCT in high-risk patients confers disease control with an acceptable toxicity profile.

Toward dual hematopoietic stem-cell transplantation and solid-organ transplantation for sickle-cell disease

Sickle-cell disease (SCD) leads to recurrent vaso-occlusive crises, chronic end-organ damage, and resultant physical, psychological, and social disabilities. Although hematopoietic stem-cell transplantation (HSCT) is potentially curative for SCD, this procedure is associated with well-recognized morbidity and mortality and thus is ideally offered only to patients at high risk of significant complications. However, it is difficult to identify patients at high risk before significant complications have occurred, and once patients experience significant organ damage, they are considered poor candidates for HSCT. In turn, patients who have experienced long-term organ toxicity from SCD such as renal or liver failure may be candidates for solid-organ transplantation (SOT); however, the transplanted organs are at risk of damage by the original disease. Thus, dual HSCT and organ transplantation could simultaneously replace the failing organ and eliminate the underlying disease process. Advances in HSCT conditioning such as reduced-intensity regimens and alternative donor selection may expand both the feasibility of and potential donor pool for transplantation. This review summarizes the current state of HSCT and organ transplantation in SCD and discusses future directions and the clinical feasibility of dual HSCT/SOT.

Reduced intensity vs. myeloablative conditioning with fludarabine and PK-guided busulfan in allogeneic stem cell transplantation for patients with AML/MDS

Conditioning regimens contribute significantly to outcomes following allogeneic stem cell transplantation (allo-SCT). Reduced-intensity conditioning (RIC) regimens provide lower toxicity at the cost of reduced efficacy compared with myeloablative conditioning (MAC) regimens. However, because pre-transplant prognostic variables often determine the conditioning regimen, studies of RIC vs. MAC have been inconclusive. We present a retrospective analysis of 242 acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) patients, 112 of whom were in 56 pairs matched using propensity scores, to account for variation that may confound clinical outcomes. The uniform conditioning regimens consisted of fludarabine with pharmacokinetic (PK)-guided intravenous busulfan (Bu). The RIC and MAC regimens were dosed at the average daily area under the concentration-vs-time curve (AUC) of 4000 µMol min and 5000-6000 µMol min, or total course AUC of 16,000 µMol min and 20,000-24,000 µMol min, respectively; PK-guided dosing removes overlap in systemic Bu exposure. When patients' data were propensity-matched, there was a trend toward significantly increased full donor chimerism and decreased chronic graft vs. host disease in RIC, and no significant differences in progression free survival and overall survival between RIC and MAC. Our results also elucidate the efficacy of PK-guided-dosing in the setting of allo-SCT for AML and MDS.

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.

Indications for Autologous and Allogeneic Hematopoietic Cell Transplantation: Guidelines from the American Society for Blood and Marrow Transplantation

Approximately 20,000 hematopoietic cell transplantation (HCT) procedures are performed in the United States annually. With advances in transplantation technology and supportive care practices, HCT has become safer, and patient survival continues to improve over time. Indications for HCT continue to evolve as research refines the role for HCT in established indications and identifies emerging indications where HCT may be beneficial. The American Society for Blood and Marrow Transplantation (ASBMT) established a multiple-stakeholder task force consisting of transplant experts, payer representatives, and a patient advocate to provide guidance on "routine" indications for HCT. This white paper presents the recommendations from the task force. Indications for HCT were categorized as follows: (1) Standard of care, where indication for HCT is well defined and supported by evidence; (2) Standard of care, clinical evidence available, where large clinical trials and observational studies are not available but HCT has been shown to be effective therapy; (3) Standard of care, rare indication, for rare diseases where HCT has demonstrated effectiveness but large clinical trials and observational studies are not feasible; (4) Developmental, for diseases where preclinical and/or early phase clinical studies show HCT to be a promising treatment option; and (5) Not generally recommended, where available evidence does not support the routine use of HCT. The ASBMT will periodically review these guidelines and will update them as new evidence becomes available.

Advances in haplo-identical stem cell transplantation in adults with high-risk hematological malignancies

Allogeneic bone marrow transplant is a life-saving procedure for adults and children that have high-risk or relapsed hematological malignancies. Incremental advances in the procedure, as well as expanded sources of donor hematopoietic cell grafts have significantly improved overall rates of success. Yet, the outcomes for patients for whom suitable donors cannot be found remain a significant limitation. These patients may benefit from a hematopoietic cell transplant wherein a relative donor is fully haplotype mismatched. Previously this procedure was limited by graft rejection, lethal graft-versus-host disease, and increased treatment-related toxicity. Recent approaches in haplo-identical transplantation have demonstrated significantly improved outcomes. Based on years of incremental pre-clinical research into this unique form of bone marrow transplant, a range of approaches have now been studied in patients in relatively large phase II trials that will be summarized in this review.

Impact of age on quality of life, functional status, and survival in patients with chronic graft-versus-host disease

Although older patients undergoing allogeneic hematopoietic stem cell transplantation (HCT) may experience higher morbidity, the impact of chronic graft-versus-host disease (GVHD) on quality of life (QOL) and survival outcomes for older compared with younger patients is currently unknown. We utilized data of patients with moderate or severe chronic GVHD (N = 522, 1661 follow-up visits, a total of 2183 visits) from the Chronic GVHD Consortium, a prospective observational multicenter cohort. We examined the relationship between age group (adolescent and young adult, "AYA," 18 to 40 years; "middle-aged," 41 to 59 years; and "older," ≥ 60 years) and QOL (Functional Assessment of Cancer Therapy-Bone Marrow Transplantation [FACT-BMT]), physical functioning (Human Activity Profile [HAP]), functional status (2-minute walk test [2MWT]), nonrelapse mortality, and overall survival. Because of multiple testing, P values < .01 were considered significant. This study included 115 (22%) AYA, 279 (53%) middle-aged, and 128 (25%) older patients with moderate (58%) or severe (42%) chronic GVHD. Despite more physical limitations in older patients as measured by worse functional status (shorter 2MWT [P < .001] and lower HAP scores [P < .001]) relative to AYA and middle-aged patients, older patients reported better QOL (FACT-BMT, P = .004) compared with middle-aged patients and similar to AYA patients (P = .99). Nonrelapse mortality and overall survival were similar between the age groups. Therefore, despite higher physical and functional limitations, older patients who are selected to undergo HSCT and survive long enough to develop moderate or severe chronic GVHD have preserved QOL and similar overall survival and nonrelapse mortality when compared with younger patients. Therefore, we did not find evidence that older age is associated with worse outcomes in patients with moderate or severe chronic GVHD.

New ways to separate graft-versus-host disease and graft-versus-tumour effects after allogeneic haematopoietic stem cell transplantation

A major challenge to transplant immunologists and physicians remains the separation of harmful graft-versus-host disease (GvHD) and beneficial graft-versus-tumour (GvT) effects after allogeneic haematopoietic stem cell transplantation. Recent advances in our understanding of the allogeneic immune response provide potential new opportunities to achieve this goal. Three potential new approaches that capitalize on this new knowledge are considered in depth; the manipulation of organ-specific cytokines and other pro-inflammatory signals, the selective manipulation of donor effector T cell migration, and the development of cell-mediated immunosuppressive strategies using donor-derived regulatory T cells. These new approaches could provide strategies for local control of allogeneic immune responses, a new paradigm to separate GvHD and GvT effects. Although these strategies are currently in their infancy and have challenges to successful translation to clinical practice, all have exciting potential for the future.

Failure of hypomethylating agent-based therapy in myelodysplastic syndromes

Hypomethylating agents such as 5-azacytidine or decitabine have been a major breakthrough in the treatment of patients with myelodysplastic syndromes (MDS). They have been shown to improve transfusion requirements and to change the natural history of the disease. However, with increasing cumulative clinical experience, it has become apparent that these agents are not curative and have their own shortcomings. There is a subgroup of patients who do not respond to frontline therapy and a large, growing cohort of patients that lose response or progress while on hypomethylating agent-based therapy. There are no standard treatment options in this arena and it is therefore a focus of significant research interest. Since the mechanisms of resistance to hypomethylating agents are not known, selection of therapy is largely empiric but must take into account the age, comorbidities, and performance status of the patient, as well as the characteristics of the disease at the time of treatment failure. Higher intensity approaches and allogeneic stem cell transplant can yield improved response rates and long-term disease control but should be limited to a selected cohort of patients who can tolerate the treatment-related morbidities. For the majority of patients who likely will be better candidates for lower intensity therapy, several novel, investigational approaches are becoming available. Among these are newer nucleoside analogues, inhibitors of protein tyrosine kinases, molecules that interact with redox signaling within the cell, immunotherapy approaches, and others. Patients with MDS whose disease has failed to respond to hypomethylating agent therapy should be referred for clinical trials when available. As we learn more about the patterns and mechanisms of failure, the next challenge will be to determine which therapies are suitable for each individual patient.

Effect of conditioning regimen intensity on acute myeloid leukemia outcomes after umbilical cord blood transplantation

Reduced-intensity conditioning (RIC) umbilical cord blood (UCB) transplantation is increasingly used in hematopoietic stem cell transplantation (HCT) for older and medically unfit patients. Data on the efficacy of HCT after RIC relative to myeloablative conditioning (MAC) are limited. We compared the outcomes of acute myeloid leukemia (AML) patients >18 yrs who received UCB grafts after either RIC or MAC. One hundred nineteen adult patients with AML in complete remission (CR) underwent an UCB transplant after RIC (n =74, 62%) or MAC (n = 45, 38%) between January 2001 and December 2009. Conditioning was either reduced intensity and consisted of cyclophosphamide 50 mg/kg, fludarabine 200 mg/m(2), and total-body irradiation (TBI) 200 cGy or myelablative and consisted for cyclophosphamide 120 mg/kg, fludarabine 75 mg/m(2), and TBI 1200-1320 cGy. All patients received cyclosporine (day -3 to day +180) and mycophenolate mofetil (day -3 to day +45) post-HCT immunosuppression and hematopoietic growth factor. Use of RIC was reserved for patients >45 years (n = 66, 89%) or preexisting severe comorbidities (n = 8, 11%). The 2 groups were similar except for preceding myelodysplastic syndrome (RIC = 28% versus MAC = 4%, P < .01) and age that was dictated by the treatment protocols (median, RIC = 55 years versus MAC = 33years; P < .01). The incidence of neutrophil recovery at day +42 was higher with RIC (94% versus MAC = 82%, P < .1), whereas platelet recovery at the sixth month was similar (RIC = 68% versus MAC = 67%, P = .30). Incidence of grade II-IV acute graft-versus-host disease (aGVHD) (RIC = 47% versus MAC = 67%, P < .01) was decreased with similar incidence of chronic GVHD (cGVHD) (RIC = 30% versus MAC = 34%, P = .43). Median follow-up for survivors was 3.8 and 4.5 years for RIC and MAC, respectively (P = .4). Using RIC, 3-year leukemia-free survival (LFS) was decreased (31% versus MAC = 55%, P = .02) and 3-year relapse incidence was increased (43% versus MAC = 9%, P < .01). Two-year transplant-related mortality (TRM) was similar (RIC = 19% versus MAC = 27%; P = .55). In multivariate analysis, RIC recipients and those in CR2 with CR1 duration <1 year had higher risk of relapse and poorer LFS with no independent predictors of TRM. UCB with RIC extends the use of allogeneic HCT for older and frail patients without excessive TRM with greater benefit for patients in CR1 and CR2 with longer CR1.

Current therapeutic approaches for patients with myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a heterogeneous spectrum of disorders requiring selective therapy based on patients' specific clinical features, predominantly their prognostic subgroups, age and performance status. Guidelines for management of patients with MDS have been generated by a number of national panels. This review focuses on evidence-based data supporting therapeutic approaches, which have also been recommended by the US National Comprehensive Cancer Network MDS Panel, with discussion of accessibility of recommended drugs in the US and in other countries. For lower risk disease (International Prognostic Scoring System Low and Intermediate-1) therapy is aimed at haematological improvement whereas for higher risk disease (Intermediate-2 and High) treatment focuses on altering disease natural history. Recent information regarding additional clinical and biological features has provided useful parameters for assessing disease prognosis that aid risk-based management decisions. The rationale for use of low versus high intensity therapies with these agents, including allogeneic haematopoietic stem cell transplantation, is discussed in detail.