Prophylaxis of graft-versus-host disease in unrelated donor transplantation with pentostatin, tacrolimus, and mini-methotrexate: a phase I/II controlled, adaptively randomized study

Hepatic graft-versus-host disease: what we know, when to biopsy, and how to diagnose

Graft-versus-host disease (GVHD) is one of the serious complications that may develop after hematopoietic cell transplantation (HCT), for hematologic malignancies, solid organ transplantation, and other hematologic disorders. GVHD develops due to T lymphocytes present in the graft attacking the host antigens, which results in tissue damage. A significant number of HCT patients develop acute or chronic GVHD, which may affect multiple organs including the liver. The diagnosis of hepatic GVHD (hGVHD) is challenging as many other conditions in HCT patients may lead to liver dysfunction. Particularly challenging among the various conditions that give rise to liver dysfunction is differentiating sinusoidal obstruction syndrome and drug-induced liver injury (DILI) from hGVHD on clinical grounds and laboratory tests. Despite the minimal risks involved in performing a liver biopsy, the information gleaned from the histopathologic changes may help in the management of these very complex patients. There is a spectrum of histologic features found in hGVHD, and most involve histopathologic changes affecting the interlobular bile ducts. These include nuclear and cytoplasmic abnormalities including dysmorphic bile ducts, apoptosis, and cholangiocyte necrosis, among others. The hepatitic form of hGVHD typically shows severe acute hepatitis. With chronic hGVHD, there is progressive bile duct loss and eventually fibrosis. Accurate diagnosis of hGVHD is paramount so that timely treatment and management can be initiated. Techniques to prevent and lower the risk of GVHD from developing have recently evolved. If a diagnosis of acute GVHD is made, the first-line of treatment is steroids. Recurrence is common and steroid resistance or dependency is not unusual in this setting. Second-line therapies differ among institutions and have not been uniformly established. The development of GVHD, particularly hGVHD, is associated with increased morbidity and mortality.

Homopurine Alkaloids: A Brief Overview

The isolation, structure elucidation, synthesis, biological properties, and biosynthesis of the homopurine alkaloids are reviewed, with an emphasis on the “victim-guardian” relationships between co-occurring alkaloids.

The Role of Extracellular Adenosine Generation in the Development of Autoimmune Diseases

Adenosine (ADO) is an immunosuppressive molecule, which suppresses the immune responses by interacting with specific receptors expressed by immune effector cells. ADO is produced from ATP through the enzymatic activities of CD39 and CD73. Alternatively, ADO can be generated starting from NAD⁺, which is metabolized by the concerted action of CD38, CD203a/PC-1, and CD73. The role of ADO in immunity has been characterized in the last years in physiology and in pathological settings. This review examines a panel of reports focused on the functions of ADO in the context of human autoimmune/inflammatory diseases and the selected animal models. The final aim is to consider the role of adenosinergic ectoenzymes and ADO receptors as novel therapeutic targets for selected diseases.

Blood and Marrow Transplant Clinical Trials Network Report on the Development of Novel Endpoints and Selection of Promising Approaches for Graft-versus-Host Disease Prevention Trials

Graft-versus-host disease (GVHD) is a common complication after hematopoietic cell transplantation (HCT) and associated with significant morbidity and mortality. Preventing GVHD without chronic therapy or increasing relapse is a desired goal. Here we report a benchmark analysis to evaluate the performance of 6 GVHD prevention strategies tested at single institutions compared with a large multicenter outcomes database as a control. Each intervention was compared with the control for the incidence of acute and chronic GVHD and overall survival and against novel composite endpoints: acute and chronic GVHD, relapse-free survival (GRFS), and chronic GVHD, relapse-free survival (CRFS). Modeling GRFS and CRFS using the benchmark analysis further informed the design of 2 clinical trials testing GVHD prophylaxis interventions. This study demonstrates the potential benefit of using an outcomes database to select promising interventions for multicenter clinical trials and proposes novel composite endpoints for use in GVHD prevention trials.

Pentostatin therapy for steroid-refractory acute graft versus host disease: identifying those who may benefit

We report outcomes of 60 patients with steroid-refractory (SR)-aGVHD treated with pentostatin. Almost half (47%) of patients had grade 4 GVHD-22% had stage 3-4 liver GVHD and 51% had stage 3-4 lower gastrointestinal tract (LGI) GVHD. Patients received a median of 3 courses (range, 1-9) of pentostatin. Day 28 overall response rate (ORR) was 33% (n = 20) (complete response 18% (n = 11), partial response 15% (n = 9)). Non-relapse mortality was 72% (95% confidence interval (CI) 61-84%) and overall survival (OS) was 21% (95% CI 12-32%) at 18 months. On univariate analysis, age >60 years (HR 1.9, 95% CI 1.01-3.7, p = 0.045) and presence of liver GVHD (HR 1.9, 95% CI 1.9, 95% CI 1.5-3.3, p = 0.03) were significant predictors of poor OS while patients with LGI GVHD had superior OS than those without (HR 0.4, 95% CI 0.2-0.8, p = 0.01). On stratified analysis, patients <60 years with isolated LGI GVHD had the best outcomes with an ORR of 48% and OS of 42% at 18 months. Among older patients, OS was 14% in those with isolated LGI aGVHD and 0% in others. Pentostatin remains a viable treatment option for SR-aGVHD, especially in patients 60 years or younger with isolated LGI involvement.

Low incidence of acute graft-versus-host disease with short-term tacrolimus in haploidentical hematopoietic stem cell transplantation

Although tacrolimus (Tac) has immunosuppressive properties and exhibits promising efficacy against graft-versus-host disease (GVHD), little is known about Tac in the prophylaxis of GVHD after HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT). In a multicenter randomized controlled trial, 174 patients received haplo-HSCT with GVHD prophylaxis involving short-term Tac (from -8days to +30days) or cyclosporine (CsA). The 100day cumulative incidences of acute GVHD (aGVHD) and grade III-IV aGVHD with the short-term Tac regimen and CsA regimen were 29.1 (19.5-38.7)% vs. 50.0(39.6-60.4)% (p=0.005) and 3.6(0.0-7.5)% vs. 13.5(6.1-20.9)% (p=0.027), respectively. There were no significant differences in the incidences of chronic GVHD (cGVHD), relapse and cytomegalovirus infection. Lymphocyte subset analysis showed that T cells decreased to lower levels on the short-term Tac regimen within 3 months of transplantation. The disease-free survival and overall survival on the short-term Tac and CsA regimens were 59.3 (48.9-69.7)% vs. 55.7 (45.3-66.1)% (p=0.696) and 65.1 (55.1-75.1)% vs. 61.4 (51.2-71.6)% (p=0.075), respectively. Our findings indicate that the short-term Tac regimen for GVHD prophylaxis in patients undergoing haplo-HSCT is associated with a low incidence and slight severity of aGVHD and did not increase the incidence of relapse and cytomegalovirus infection.

Novel approaches for preventing acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (alloHSCT) offers potential curative treatment for a wide range of malignant and nonmalignant hematological disorders. However, its success may be limited by post-transplant acute graft-versus-host disease (aGVHD), a systemic syndrome in which donor's immune cells attack healthy tissues in the immunocompromised host. aGVHD is one of the main causes of morbidity and mortality after alloHSCT. Despite standard GVHD prophylaxis regimens, aGVHD still develops in approximately 40-60% of alloHSCT recipients.

AREAS COVERED

In this review, after a brief summary of current knowledge on the pathogenesis of aGVHD, the authors review the current combination of a calcineurin inhibitor with an antimetabolite with or without added anti-thymocyte globulin (ATG) and emerging strategies for GVHD prevention.

EXPERT OPINION

A new understanding of the involvement of cytokines, intracellular signaling pathways, epigenetics and immunoregulatory cells in GVHD pathogenesis will lead to new standards for aGVHD prophylaxis allowing better prevention of severe aGVHD without affecting graft-versus-tumor effects.

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.

The end of knight-errantry in GVHD studies

In this issue of Blood, Bolaños-Meade et al reported the results of the randomized phase 3 study Blood and Marrow Transplant Clinical Trials Network (BMTCTN) 0802. It compared the addition of mycophenolate mofetil to steroids vs steroids/placebo to treat newly diagnosed acute graft-versus-host disease (GVHD). Unfortunately, it failed to show a significant difference in outcomes.

Current and emerging strategies for the prevention of graft-versus-host disease

Graft-versus-host disease (GVHD) represents the most serious and challenging complication of allogeneic haematopoietic stem-cell transplantation (HSCT). New insights on the role of regulatory T-cells, T cells, and antigen-presenting cells have led to an improved understanding of the pathophysiology of GVHD. However, little progress has been made since the introduction of calcineurin-inhibitor-based regimens in the mid-1980s. Despite standard prophylaxis with these regimens, GVHD still develops in approximately 40-60% of recipients. Thus, there is a need for developing newer approaches to mitigate GVHD, which may facilitate the use of allogeneic HSCT for the treatment of a wider range of haematological cancers. We discuss the rationale, clinical evidence, and outcomes of current (and widely employed) strategies for GVHD prophylaxis, namely calcineurin-inhibitor-based regimens (such as cyclosporine or tacrolimus) combined with methotrexate or mycophenolate mofetil. We assess the clinical evidence for emerging approaches in the prevention of GVHD, including therapies targeting T cells or B cells, the use of mesenchymal stem cells, chemo-cytokine antagonists (such as maraviroc, TNF-α inhibitor, IL-2 receptor antagonist, IL-6 inhibitor), and the use of novel molecular regulators that target multiple cell types simultaneously, including atorvastatin, bortezomib, and epigenetic modulators.

Dose intensification of busulfan in the preparative regimen is associated with improved survival: a phase I/II controlled, randomized study

Dose intensity is important for disease control in patients undergoing allogeneic stem cell transplantation. We conducted a phase I/II controlled, adoptive, randomized study to determine the optimal dosing schedule of i.v. busulfan. Patients aged ≤75 years with advanced hematologic malignancies with human leukocyte antigen-compatible donor were eligible. All patients received fludarabine at 30 mg/m(2)/d for 4 days, and busulfan was administered in different doses in oral or i.v. formulations. As determined by the phase I trial, i.v. busulfan at a dose of 11.2 mg/kg/d was used for the phase II expansion cohort. Altogether, 80 patients with a median age of 56 years were enrolled. Forty percent had active disease at the time of transplantation. Engraftment occurred in 91%, and a complete response was achieved in 79% of patients posttransplantation. At a median follow-up of 91 months in the surviving patients, the outcomes for i.v. busulfan dose of 11.2 mg/kg/d versus other doses were as follows: nonrelapse mortality, 34% versus 23% (P = .4); cumulative incidence of relapse, 43% versus 68% (P = .02); relapse-free survival, 25% versus 9% (P = .017); and overall survival, 27% versus 9% (P = .02). We conclude that optimizing i.v. busulfan dose intensity in the preparative regimen may overcome disease-associated poor prognostic factors.

Significance of persistent cytogenetic abnormalities on myeloablative allogeneic stem cell transplantation in first complete remission

Risk stratification is important to identify patients with acute myelogenous leukemia (AML) who might benefit from allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission. We retrospectively studied 150 patients with AML and diagnostic cytogenetic abnormalities who underwent myeloablative allo-HSCT while in first complete remission to evaluate the prognostic impact of persistent cytogenetic abnormalities at allo-HSCT. Three risk groups were identified. Patients with favorable/intermediate cytogenetics at diagnosis (n = 49) and patients with unfavorable cytogenetics at diagnosis but without a persistent abnormal clone at allo-HSCT (n = 83) had a similar 3-year leukemia-free survival of 58%-60% despite the higher 3-year relapse incidence (RI) in the latter group (32.3%, versus 16.8% in the former group). A third group of patients with unfavorable cytogenetics at diagnosis and a persistent abnormal clone at allo-HSCT (n = 15) had the worst prognosis, with a 3-year RI of 57.5% and 3-year leukemia-free survival of only 29.2%. These data suggest that patients with AML and unfavorable cytogenetics at diagnosis and a persistent abnormal clone at allo-HSCT are at high risk for relapse after allo-HSCT. These patients should be considered for clinical trials designed to optimize conditioning regimens and/or to use preemptive strategies in the posttransplantion setting aimed at decreasing RI.

Prevention of graft-vs.-host disease

INTRODUCTION

Allogeneic hematopoietic cell transplantation (HCT) is a curative treatment for many malignant and non-malignant hematologic disorders. However, graft-vs.-host disease (GVHD) remains a major complication of allogeneic HCT and limits the success of this approach.

AREAS COVERED

This paper reviews recent developments in the prevention of acute and chronic GVHD. In the setting of acute GVHD prevention, recent trials of T-cell depletion using Fresenius-ATG are reviewed, as well as studies testing total lymphoid irradiation, mesenchymal stromal cells, rituximab, statins, sirolimus and other investigational agents. In the setting of chronic GVHD, results with Fresenius-ATG are reviewed, as well as B-cell depletion with rituximab, and the potential role of the B-cell regulatory cytokine BAFF in chronic GVHD is also discussed. Finally, the emerging role of resident skin and gut bacterial flora-the so-called microbiome-in the pathogenesis of GVHD is covered.

EXPERT OPINION

Current methods of acute GVHD prevention are highly successful, and a number of investigational approaches promise to further reduce the risk of this complication. By contrast, chronic GVHD is more poorly understood and more difficult to prevent. Future studies are required to delineate the roles of these approaches and to abrogate GVHD without sacrificing the beneficial immunologic graft-vs.-tumor effect.

Anti-thymocyte globulin (thymoglobulin), tacrolimus, and sirolimus as acute graft-versus-host disease prophylaxis for unrelated hematopoietic stem cell transplantation

Acute graft-versus-host disease (aGVHD) is a major cause of morbidity and mortality in patients undergoing unrelated hematopoietic stem cell transplantation. We prospectively evaluated the efficacy of intermediate-dose rabbit anti-thymocyte globulin (Thymoglobulin® a total of 4.5 mg/kg given over days -3, -2, and -1) in combination with tacrolimus and sirolimus for the prevention of aGVHD. We enrolled 47 recipients who underwent unrelated hematopoietic stem cell transplantation. Patients received daily granulocyte colony-stimulating factor starting on day +6 until neutrophil engraftment (median duration, 11 days; range, 9-15 days). Twenty-two patients received HLA 8/8 and 25 received 7/8 matched grafts, respectively. The median follow-up duration was 23.6 months (range, 18.8-27.9 months). The cumulative incidence of grade II to IV aGVHD was 23.4% (95% confidence interval, 12.4-36.3). At 2-year follow-up, the cumulative incidence of nonrelapse mortality was 31.9%, cumulative incidence of relapse was 24.6%, and cumulative incidence of chronic GVHD was 33%. Progression-free survival at 1 year was 54%, with a median of 17.7 months. Overall survival at 1 year was 65%, with no median reached. These results suggest that the combination of Thymoglobulin, tacrolimus, and sirolimus in patients undergoing unrelated hematopoietic stem cell transplantation is well tolerated and associated with a low incidence and severity of aGVHD and chronic graft-versus-host disease.

Optimizing management of myelodysplastic syndromes post-allogeneic transplantation

Allogeneic hematopoietic stem cell transplantation is still the only potentially curative treatment for patients with myelodysplastic syndromes. Improvements in donor selection, supportive care and the introduction of reduced-intensity conditioning have led to a decrease in early transplant mortality. However, relapse rates have not changed significantly in recent years. Furthermore, treatment options for patients relapsing after hematopoietic stem cell transplantation are limited and often short-lived. Thus, optimizing the post-transplant outcome by maintenance approaches or minimal residual disease-directed preemptive therapy is an important goal of current clinical research. Further strategies aiming at an improved prevention of graft-versus-host disease are currently under investigation.

Have we improved in preventing and treating acute graft-versus-host disease?

PURPOSE OF REVIEW

Acute graft-versus-host disease (GVHD) is a considerable source of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Accordingly, progress in the prevention and primary therapy of this complication is needed to improve patient outcomes.

RECENT FINDINGS

Guided by insights into acute GVHD pathogenesis, investigators have explored novel cellular and pharmacologic approaches to acute GVHD prevention that demonstrates promise. Although pan-T-cell depletion has reduced GVHD, novel strategies that selectively deplete alloreactive T cells or modulate the balance of effector T cells and regulatory T cells offer promise to selectively abrogate acute GVHD while retaining protection from primary disease relapse and infectious complications.

SUMMARY

Divergent approaches in the primary therapy of acute GVHD have explored both combination approaches with standard dose glucocorticoids and additional immunosuppressive agents and conversely steroid-sparing approaches including topical agents such as beclomethasone or sirolimus as a steroid-free approach to acute GVHD therapy. Mature results of high-quality clinical trials are needed to determine the optimal therapy that results in effective control of the syndrome and limited toxicity. These complementary outcomes represent the therapeutic goal for future investigation in acute GVHD therapy.