The addition of sirolimus to the graft-versus-host disease prophylaxis regimen in reduced intensity allogeneic stem cell transplantation for lymphoma: a multicentre randomized trial

Novel developments in the prophylaxis and treatment of acute GVHD

Acute graft-versus-host disease (aGVHD) is a major life-threatening complication after allogeneic hematopoietic cell transplant. Traditional standard prophylaxis for aGVHD has included a calcineurin inhibitor plus an antimetabolite, whereas treatment has relied mainly on corticosteroids, followed by multiple nonstandard second-line options. In the past decade, this basic framework has been reshaped by approval of antithymocyte globulin products, the emergence of posttransplant cyclophosphamide, and recent pivotal trials studying abatacept and vedolizumab for GVHD prophylaxis, whereas ruxolitinib was approved for corticosteroid-refractory aGVHD treatment. Because of this progress, routine acute GVHD prophylaxis and treatment practices are starting to shift, and results of ongoing trials are eagerly awaited. Here, we review recent developments in aGVHD prevention and therapy, along with ongoing and future planned clinical trials in this space, outlining what future goals should be and the limitations of current clinical trial designs and end points.

Checkpoint Inhibitors and the Changing Face of the Relapsed/Refractory Classical Hodgkin Lymphoma Pathway

PURPOSE OF REVIEW

Checkpoint inhibitors (CPIs) targeting PD1 are highly active in relapsed/refractory classical Hodgkin lymphoma. A plethora of recent studies, often small and non-randomised, have raised many questions about how to optimally integrate these into clinical practice. We aim to discuss the use of CPIs in different relapsed/refractory settings in an effort to better define their role and highlight areas of research.

RECENT FINDINGS

CPIs have shown efficacy at first relapse, as salvage pre- and post-autologous (ASCT) and allogeneic stem cell transplant (alloSCT) and as maintenance post-ASCT. Immune-related adverse events require careful attention, especially when used peri-alloSCT, where it is associated with hyperacute graft-versus-host disease. Newer PD1 inhibitors, as well as strategies to overcome CPI resistance, are being tested. CPIs are increasingly deployed at earlier points in the classical Hodgkin lymphoma pathway. Whilst progress is clearly being made, randomised studies are required to more clearly define the optimal positioning of these agents.

Kinase Inhibition as Treatment for Acute and Chronic Graft-Versus-Host Disease

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potentially curative therapy for patients suffering from hematological malignancies via the donor immune system driven graft-versus-leukemia effect. However, the therapy is mainly limited by severe acute and chronic graft-versus-host disease (GvHD), both being life-threatening complications after allo-HCT. GvHD develops when donor T cells do not only recognize remaining tumor cells as foreign, but also the recipient’s tissue, leading to a severe inflammatory disease. Typical GvHD target organs include the skin, liver and intestinal tract. Currently all approved strategies for GvHD treatment are immunosuppressive therapies, with the first-line therapy being glucocorticoids. However, therapeutic options for glucocorticoid-refractory patients are still limited. Novel therapeutic approaches, which reduce GvHD severity while preserving GvL activity, are urgently needed. Targeting kinase activity with small molecule inhibitors has shown promising results in preclinical animal models and clinical trials. Well-studied kinase targets in GvHD include Rho-associated coiled-coil-containing kinase 2 (ROCK2), spleen tyrosine kinase (SYK), Bruton’s tyrosine kinase (BTK) and interleukin-2-inducible T-cell kinase (ITK) to control B- and T-cell activation in acute and chronic GvHD. Janus Kinase 1 (JAK1) and 2 (JAK2) are among the most intensively studied kinases in GvHD due to their importance in cytokine production and inflammatory cell activation and migration. Here, we discuss the role of kinase inhibition as novel treatment strategies for acute and chronic GvHD after allo-HCT.

Immunometabolic Therapeutic Targets of Graft-versus-Host Disease (GvHD)

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative option in the treatment of aggressive malignant and non-malignant blood disorders. However, the benefits of allo-HSCT can be compromised by graft-versus-host disease (GvHD), a prevalent and morbid complication of allo-HSCT. GvHD occurs when donor immune cells mount an alloreactive response against host antigens due to histocompatibility differences between the donor and host, which may result in extensive tissue injury. The reprogramming of cellular metabolism is a feature of GvHD that is associated with the differentiation of donor CD4+ cells into the pathogenic Th1 and Th17 subsets along with the dysfunction of the immune-suppressive protective T regulatory cells (Tregs). The activation of glycolysis and glutaminolysis with concomitant changes in fatty acid oxidation metabolism fuel the anabolic activities of the proliferative alloreactive microenvironment characteristic of GvHD. Thus, metabolic therapies such as glycolytic enzyme inhibitors and fatty acid metabolism modulators are a promising therapeutic strategy for GvHD. We comprehensively review the role of cellular metabolism in GvHD pathogenesis, identify candidate therapeutic targets, and describe potential strategies for augmenting immunometabolism to ameliorate GvHD.

The Addition of Sirolimus to GVHD Prophylaxis After Allogeneic Hematopoietic Stem Cell Transplantation: A Meta-Analysis of Efficacy and Safety

Objective

The objective of this study was to evaluate the safety and efficacy of sirolimus (SRL) in the prevention of graft-versus-host disease (GVHD) in recipients following allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Methods

Randomized controlled trials (RCTs) evaluating the safety and efficacy of SRL-based prophylaxis regimens in patients receiving allo-HSCT were obtained from PubMed, Embase, and the Cochrane database. Following specific inclusion and exclusion criteria, studies were selected and screened by two independent reviewers who subsequently extracted the study data. The Cochrane risk bias evaluation tool was used for quality evaluation, and RevMan 5.3 software was used for statistical analysis comparing the effects of SRL-based and non–SRL-based regimens on acute GVHD, chronic GVHD, overall survival (OS), relapse rate, non-relapse mortality (NRM), thrombotic microangiopathy (TMA), and veno-occlusive disease (VOD).

Results

Seven studies were included in this meta-analysis, with a total sample size of 1,673 cases, including 778 cases of patients receiving SRL-based regimens and 895 cases in which patients received non-SRL-based regimens. Our data revealed that SRL containing prophylaxis can effectively reduce the incidence of grade II–IV acute GVHD (RR = 0.75, 95% CI: 0.68∼0.82, p < 0.0001). SRL-based prophylaxis was not associated with an improvement of grade III–IV acute GVHD (RR = 0.78, 95% CI: 0.59∼1.03, p = 0.08), chronic GVHD (p = 0.89), OS (p = 0.98), and relapse rate (p = 0.16). Despite its immunosuppressant effects, SRL-based regimens did not increase bacterial (p = 0.68), fungal (p = 0.70), or CMV (p = 0.10) infections. However, patients receiving SRL-based regimens had increased TMA (p < 0.00001) and VOD (p < 0.00001).

Conclusions

This meta-analysis indicates that addition of sirolimus is an effective alternative prophylaxis strategy for II–IV aGVHD but may cause endothelial cell injury and result in secondary TMA or VOD events.

Hematopoietic Cell Transplantation, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Hematopoietic cell transplantation (HCT) involves the infusion of hematopoietic progenitor cells into patients with hematologic disorders with the goal of re-establishing normal hematopoietic and immune function. HCT is classified as autologous or allogeneic based on the origin of hematopoietic cells. Autologous HCT uses the patient's own cells while allogeneic HCT uses hematopoietic cells from a human leukocyte antigen-compatible donor. Allogeneic HCT is a potentially curative treatment option for patients with certain types of hematologic malignancies, and autologous HCT is primarily used to support patients undergoing high-dose chemotherapy. Advances in HCT methods and supportive care in recent decades have led to improved survival after HCT; however, disease relapse and posttransplant complications still commonly occur in both autologous and allogeneic HCT recipients. Allogeneic HCT recipients may also develop acute and/or chronic graft-versus-host disease (GVHD), which results in immune-mediated cellular injury of several organs. The NCCN Guidelines for Hematopoietic Cell Transplantation focus on recommendations for pretransplant recipient evaluation and the management of GVHD in adult patients with malignant disease.

Autophagy-targeted therapy to modulate age-related diseases: Success, pitfalls, and new directions

Autophagy is a critical metabolic process that supports homeostasis at a basal level and is dynamically regulated in response to various physiological and pathological processes. Autophagy has some etiologic implications that support certain pathological processes due to alterations in the lysosomal-degradative pathway. Some of the conditions related to autophagy play key roles in highly relevant human diseases, e.g., cardiovascular diseases (15.5%), malignant and other neoplasms (9.4%), and neurodegenerative conditions (3.7%). Despite advances in the discovery of new strategies to treat these age-related diseases, autophagy has emerged as a therapeutic option after preclinical and clinical studies. Here, we discuss the pitfalls and success in regulating autophagy initiation and its lysosome-dependent pathway to restore its homeostatic role and mediate therapeutic effects for cancer, neurodegenerative, and cardiac diseases. The main challenge for the development of autophagy regulators for clinical application is the lack of specificity of the repurposed drugs, due to the low pharmacological uniqueness of their target, including those that target the PI3K/AKT/mTOR and AMPK pathway. Then, future efforts must be conducted to deal with this scenery, including the disclosure of key components in the autophagy machinery that may intervene in its therapeutic regulation. Among all efforts, those focusing on the development of novel allosteric inhibitors against autophagy inducers, as well as those targeting autolysosomal function, and their integration into therapeutic regimens should remain a priority for the field.

Allogeneic hematopoietic cell transplantation with non-myeloablative conditioning for patients with hematologic malignancies: Improved outcomes over two decades

We have used a non-myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation for the past twenty years. During that period, changes in clinical practice have been aimed at reducing morbidity and mortality from infections, organ toxicity, and graft-versus-host disease. We hypothesized that improvements in clinical practice led to better transplantation outcomes over time. From 1997-2017, 1,720 patients with hematologic malignancies received low-dose total body irradiation +/- fludarabine or clofarabine before transplantation from HLA-matched sibling or unrelated donors, followed by mycophenolate mofetil and a calcineurin inhibitor ± sirolimus. We compared outcomes in three cohorts by year of transplantation: 1997 +/- 2003 (n=562), 2004 +/- 2009 (n=594), and 2010 +/- 2017 (n=564). The proportion of patients ≥60 years old increased from 27% in 1997 +/- 2003 to 56% in 2010-2017, and with scores from the Hematopoietic Cell Transplantation Comborbidity Index of ≥3 increased from 25% in 1997 +/- 2003 to 45% in 2010 +/- 2017. Use of unrelated donors increased from 34% in 1997 +/- 2003 to 65% in 2010-2017. When outcomes from 2004 +/- 2009 and 2010-2017 were compared to 1997 +/- 2003, improvements were noted in overall survival (P=.0001 for 2004-2009 and P <.0001 for 2010-2017), profression-free survival (P=.002 for 2004-2009 and P <.0001 for 2010 +/- 2017), non-relapse mortality (P<.0001 for 2004 +/- 2009 and P <.0001 for 2010 +/- 2017), and in rates of grades 2 +/- 4 acute and chronic graft-vs.-host disease. For patients with hematologic malignancies who underwent transplantation with non-myeloablative conditioning, outcomes have improved during the past two decades. Trials reported are registered under ClinicalTrials.gov identifiers: NCT00003145, NCT00003196, NCT00003954, NCT00005799, NCT00005801, NCT00005803, NCT00006251, NCT00014235, NCT00027820, NCT00031655, NCT00036738, NCT00045435, NCT00052546, NCT00060424, NCT00075478, NCT00078858, NCT00089011, NCT00104858, NCT00105001, NCT00110058, NCT00397813, NCT00793572, NCT01231412, NCT01252667, NCT01527045.

GVHD Prophylaxis 2020

Graft-vs. host disease (GVHD), both acute and chronic are among the chief non-relapse complications of allogeneic transplantation which still cause substantial morbidity and mortality despite significant advances in supportive care over the last few decades. The prevention of GVHD therefore remains critical to the success of allogeneic transplantation. In this review we briefly discuss the pathophysiology and immunobiology of GVHD and the current standards in the field which remain centered around calcineurin inhibitors. We then discuss important translational advances in GVHD prophylaxis, approaching these various platforms from a mechanistic standpoint based on the pathophysiology of GVHD including in-vivo and ex-vivo T-cell depletion alongwith methods of selective T-cell depletion, modulation of T-cell co-stimulatory pathways (checkpoints), enhancing regulatory T-cells (Tregs), targeting T-cell trafficking as well as cytokine pathways. Finally we highlight exciting novel pre-clinical research that has the potential to translate to the clinic successfully. We approach these methods from a pathophysiology based perspective as well and touch upon strategies targeting the interaction between tissue damage induced antigens and T-cells, regimen related endothelial toxicity, T-cell co-stimulatory pathways and other T-cell modulatory approaches, T-cell trafficking, and cytokine pathways. We end this review with a critical discussion of existing data and novel therapies that may be transformative in the field in the near future as a comprehensive picture of GVHD prophylaxis in 2020. While calcineurin inhibitors remain the standard, post-transplant eparinsphamide originally developed to facilitate haploidentical transplantation is becoming an attractive alternative to traditional calcinuerin inhibitor based prophylaxis due to its ability to reduce severe forms of acute and chronic GVHD without compromising other outcomes, even in the HLA-matched setting. In addition T-cell modulation, particularly targeting some important T-cell co-stimulatory pathways have resulted in promising outcomes and may be a part of GVHD prophylaxis in the future. Novel approaches including targeting early events in GVHD pathogenesis such as interactions bvetween tissue damage associated antigens and T-cells, endothelial toxicity, and T-cell trafficking are also promising and discussed in this review. GVHD prophylaxis in 2020 continues to evolve with novel exicitng therapies on the horizon based on a more sophisticated understanding of the immunobiology of GVHD.

Uncovering the multifaceted roles played by neutrophils in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT.

A prospective single-center study on CNI-free GVHD prophylaxis with everolimus plus mycophenolate mofetil in allogeneic HCT

We report a single-center phase I/II trial exploring the combination of everolimus (EVE) and mycophenolate mofetil (MMF) as calcineurin inhibitor (CNI)-free GVHD prophylaxis for 24 patients with hematologic malignancies and indication for allogeneic HCT after a high dose or reduced-intensity ablative conditioning. The study was registered as EudraCT-2007-001892-12 and Clinicaltrials.gov as NCT00856505. All patients received PBSC grafts and no graft failure occurred. 7/24 patients (29%) developed acute grades III and IV GVHD (aGVHD), 16/19 evaluable patients (84%) developed chronic GVHD (cGVHD) of all grades, and 6/19 (31.6%) of higher grades. No severe toxicities related to study medication were observed. The median follow-up of all surviving patients is 2177 days. The 3-year OS was 45.2% (95% CI: 27.4–61.4%), and the 3-year PFS was 38.7% (95% CI: 22.0–55.1%). The cumulative incidence of relapse at 1 year and 3 year was 25% (95% CI: 12.5–50.0%), and 33.3% (95% CI: 18.9–58.7%), the cumulative incidence of NRM at 1 year and 3 years was 20.8% (95%CI: 9.6–45.5%), and 29.2% (95%CI: 15.6–54.4%), respectively. The utilization of CNI-free GVHD prophylaxis with EVE+MMF resulted in high rates of acute and chronic GVHD. Therefore, we do not recommend a CNI-free combination of mTOR inhibitor EVE with MMF as the sole GVHD prophylaxis. In subsequent studies, this combination should be modified, e.g., with further components like post-transplant cyclophosphamide (PTCy) or anti-thymocyte globulin (ATG).

Endothelial mTOR maintains hematopoiesis during aging

Aging leads to a decline in hematopoietic stem and progenitor cell (HSPC) function. We recently discovered that aging of bone marrow endothelial cells (BMECs) leads to an altered crosstalk between the BMEC niche and HSPCs, which instructs young HSPCs to behave as aged HSPCs. Here, we demonstrate aging leads to a decrease in mTOR signaling within BMECs that potentially underlies the age-related impairment of their niche activity. Our findings reveal that pharmacological inhibition of mTOR using Rapamycin has deleterious effects on hematopoiesis. To formally determine whether endothelial-specific inhibition of mTOR can influence hematopoietic aging, we conditionally deleted mTOR in ECs (mTOR^(ECKO)) of young mice and observed that their HSPCs displayed attributes of an aged hematopoietic system. Transcriptional profiling of HSPCs from mTOR^(ECKO) mice revealed that their transcriptome resembled aged HSPCs. Notably, during serial transplantations, exposure of wild-type HSPCs to an mTOR^(ECKO) microenvironment was sufficient to recapitulate aging-associated phenotypes, confirming the instructive role of EC-derived signals in governing HSPC aging.

The Role of mTOR Inhibitors in Hematologic Disease: From Bench to Bedside

The mTOR pathway plays a central role in many cellular processes, such as cellular growth, protein synthesis, glucose, and lipid metabolism. Aberrant regulation of mTOR is a hallmark of many cancers, including hematological malignancies. mTOR inhibitors, such as Rapamycin and Rapamycin analogs (Rapalogs), have become a promising class of agents to treat malignant blood diseases-either alone or in combination with other treatment regimens. This review highlights experimental evidence underlying the molecular mechanisms of mTOR inhibitors and summarizes their evolving role in the treatment of hematologic disease, including leukemia, lymphoma, myeloma, immune hemocytopenia, and graft-versus-host disease (GVHD). Based on data presented in this review, we believe that mTOR inhibitors are becoming a trusted therapeutic in the clinical hematologist's toolbelt and should be considered more routinely in combination therapy for the management of hematologic disease.

Graft-versus-host disease prophylaxis: Pathophysiology-based review on current approaches and future directions

Graft-versus-host disease (GvHD) was first described in 1959, since then major efforts have been made in order to understand its physiopathology and animal models have played a key role. Three steps, involving different pathways, have been recognised in either acute and chronic GvHD, identifying them as two distinct entities. In order to reduce GvHD incidence and severity, prophylactic measures were added to transplant protocols. The combination of a calcineurin inhibitor (CNI) plus an antimetabolite remains the standard of care. Better knowledge of GvHD pathophysiology has moved this field forward and nowadays different drugs are being used on a daily basis. Improving GvHD prophylaxis is a major goal as it would translate into less non-relapse mortality and better overall survival. As compared to CNI plus methotrexate the combination of CNI plus mycophenolate mophetil (MMF) allows us to obtain similar results in terms of GvHD incidence but a lower toxicity rate in terms of neutropenia or mucositis. The use of ATG has been related to a lower risk of acute and chronic GvHD in prospective randomized trials as well as the use of posttransplant Cyclophosphamide, with no or marginal impact on overall survival but with an improvement in GvHD-relapse free survival (GRFS). The use of sirolimus has been related to a lower risk of acute GvHD and significantly influenced overall survival in one prospective randomized trial. Other prospective trials have evaluated the use of receptors such as CCR5 or α4β7 to avoid T-cells trafficking into GvHD target organs, cytokine blockers or immune check point agonists. Also, epigenetic modifiers have shown promising results in phase II trials. Attention should be paid to graft-versus-leukemia, infections and immune recovery before bringing new prophylactic strategies to clinical practice. Although the list of novel agents for GvHD prophylaxis is growing, randomized trials are still lacking for many of them.

Conversion from calcineurin inhibitors to sirolimus in transplant-associated thrombotic microangiopathy

Transplant-associated thrombotic microangiopathy (TA-TMA) is a specific complication of allogeneic hematopoietic cell transplantation with a multifactorial etiology. There is little evidence published regarding the efficacy and factors influencing the outcome of substitution of calcineurin inhibitors (CNIs) with other agentsas a widely accepted practice in this disorder; however, there are limited data on the options for immunosuppression manipulation (ISM). In our study, we retrospectively analyzed outcomes of 45 patients with TA-TMA with ISM and substitution either with steroids (steroid group) or anmTOR inhibitor sirolimus (sirolimus group). In our study, sirolimus was associated with significantly better 1-year overall survival (HR 0.3, 95% CI 0.13-0.7, p = .004) and faster time to normalization of LDH (HR 2.2, 95% CI 0.99-4.99, p = .044). Replacing CNIs with sirolimus could be an effective option in patients with TA-TMA. A multicenter confirmatory study of CNIs replacement with sirolimus is justified.

History of hematopoietic cell transplantation: challenges and progress

After more than 60 years of research in allogeneic hematopoietic cell transplantation (HCT), this therapy has advanced from one that was declared dead in the 1960s to a standard treatment of otherwise fatal malignant and non-malignant blood diseases. To date, close to 1.5 million hematopoietic cell transplants have been performed in more than 1,500 transplantation centers worldwide. This review will highlight the enormous efforts by numerous investigators throughout the world who have brought the experimental field of HCT to clinical reality, examine ongoing challenges, and provide insights for the future.

Translational and clinical advances in acute graft-versus-host disease

Acute graft-versus-host disease (aGvHD) is induced by immunocompetent alloreactive T lymphocytes in the donor graft responding to polymorphic and non-polymorphic host antigens and causing inflammation in primarily the skin, gastrointestinal tract and liver. aGvHD remains an important toxicity of allogeneic transplantation, and the search for better prophylactic and therapeutic strategies is critical to improve transplant outcomes. In this review, we discuss the significant translational and clinical advances in the field which have evolved based on a better understanding of transplant immunology. Prophylactic advances have been primarily focused on the depletion of T lymphocytes and modulation of T-cell activation, proliferation, effector and regulatory functions. Therapeutic strategies beyond corticosteroids have focused on inhibiting key cytokine pathways, lymphocyte trafficking, and immunologic tolerance. We also briefly discuss important future trends in the field, the role of the intestinal microbiome and dysbiosis, as well as prognostic biomarkers for aGvHD which may improve stratification-based application of preventive and therapeutic strategies.

Feasibility of thiotepa addition to the fludarabine-busulfan conditioning with tacrolimus/sirolimus as graft vs host disease prophylaxis

In classical reduced-intensity conditioning (RIC) regimens, including the fludarabine and busulphan (BF) combination, sirolimus and tacrolimus (SIR-TAC) as graft vs host disease (GVHD) prophylaxis has shown acceptable results. The outcomes of SIR-TAC in a more intense RIC regimen as Thiotepa-fludarabine-busulfan (TBF) have been hardly investigated. This retrospective study included all consecutive patients receiving an allogeneic hematopoietic stem cell transplantation for myeloid malignancies (January 2009-2017) conditioned with either TBF or BF and receiving SIR-TAC. Patients receiving TBF presented higher non-relapse mortality (31.6 vs 12.3%, p = .01), along with shorter overall survival (51.8% vs 77.8%, p < .01) at 2 years than patients treated with BF. There were no significant differences in the cumulative incidence of grade II-IV acute GVHD or moderate-severe chronic GVHD or relapse between both groups. These results suggest that TBF does not seem to improve the traditional RIC BF regimen, at least when associated with SIR-TAC prophylaxis.

Distinct Regulatory and Effector T Cell Metabolic Demands during Graft-Versus-Host Disease

Despite graft-versus-host disease (GVHD) prophylactic agents, the success and wider utilization of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is limited by GVHD. Increasing donor graft regulatory T cell (Treg):effector T cell (Teff) ratios can substantially reduce GVHD in cancer patients, but pre-HSCT conditioning regimens and GVHD create a challenging inflammatory environment for Treg stability, persistence, and function. Metabolism plays a crucial role in T cell and Treg differentiation, and development of effector function. Although glycolysis is a main driver of allogeneic T cell-driven GVHD, oxidative phosphorylation is a main driver of Treg suppressor function. This review focuses on recent advances in our understanding of Treg metabolism in the context of GVHD, and discusses potential therapeutic applications of Tregs in the prevention or treatment of GVHD in cancer patients.

Allogeneic Stem Cell Transplantation with CD34+ Cell Selection

The success of allogeneic stem cell transplant is hampered by the development of acute and chronic graft-versus-host disease (GvHD) which has direct impact on treatment-related mortality and morbidity. As a result, T cell depletion through positive selection of CD34+ cells has emerged as a promising strategy to reduce acute and chronic GvHD in these patients.

In this review, we summarize the main characteristics of allogeneic stem cell transplant with CD34+ cell selection including risks of graft failure, GvHD, infection, organ toxicity, and long-term survival. Moreover, we highlight future strategies to improve the results of this platform and to consolidate its use in clinical practice.

Addition of sirolimus to standard cyclosporine plus mycophenolate mofetil-based graft-versus-host disease prophylaxis for patients after unrelated non-myeloablative haemopoietic stem cell transplantation: a multicentre, randomised, phase 3 trial

BACKGROUND

Acute graft-versus-host-disease (GVHD) after non-myeloablative human leucocyte antigen (HLA)-matched, unrelated donor, allogeneic haemopoietic stem cell transplantation (HSCT) is associated with considerable morbidity and mortality. This trial aimed to evaluate the efficacy of adding sirolimus to the standard cyclosporine and mycophenolate mofetil prophylaxis therapy for preventing acute GVHD in this setting.

METHODS

This multicentre, randomised, phase 3 trial took place at nine HSCT centres based in the USA, Denmark, and Germany. Eligible patients were diagnosed with advanced haematological malignancies treatable by allogeneic HSCT, had a Karnofsky score greater than or equal to 60, were aged older than 50 years, or if they were aged 50 years or younger, were considered at high risk of regimen-related toxicity associated with a high-dose pre-transplantation conditioning regimen. Patients were randomly allocated by an adaptive randomisation scheme stratified by transplantation centre to receive either the standard GVHD prophylaxis regimen (cyclosporine and mycophenolate mofetil) or the triple-drug combination regimen (cyclosporine, mycophenolate mofetil, and sirolimus). Patients and physicians were not masked to treatment. All patients were prepared for HSCT with fludarabine (30 mg/m² per day) 4, 3, and 2 days before receiving 2 or 3 Gy total body irradiation on the day of HSCT (day 0). In both study groups, 5·0 mg/kg of cyclosporine was administered orally twice daily starting 3 days before HSCT, and (in the absence of GVHD) tapered from day 96 through to day 150. In the standard GVHD prophylaxis group, 15 mg/kg of mycophenolate mofetil was given orally three times daily from day 0 until day 30, then twice daily until day 150, and (in the absence of GVHD) tapered off by day 180. In the triple-drug group, mycophenolate mofetil doses were the same as in the standard group, but the drug was discontinued on day 40. Sirolimus was started 3 days before HSCT, taken orally at 2 mg once daily and adjusted to maintain trough concentrations between 3-12 ng/mL through to day 150, and (in the absence of GVHD) tapered off by day 180. The primary endpoint was the cumulative incidence of grade 2-4 acute GVHD at day 100 post-transplantation. Secondary endpoints were non-relapse mortality, overall survival, progression-free survival, cumulative incidence of grade 3-4 acute GVHD, and cumulative incidence of chronic GVHD. Efficacy and safety analyses were per protocol, including all patients who received conditioning treatment and underwent transplantation. Toxic effects were measured according to the Common Terminology Criteria for Adverse Events (CTCAE). The current study was closed prematurely by recommendation of the Data and Safety Monitoring Board on July 27, 2016, after 168 patients received the allocated intervention, based on the results of a prespecified interim analysis for futility. This study is registered with ClinicalTrials.gov, number NCT01231412.

FINDINGS

Participants were recruited between Nov 1, 2010, and July 27, 2016. Of 180 patients enrolled in the study, 167 received the complete study intervention and were included in safety and efficacy analyses: 77 patients in the standard GVHD prophylaxis group and 90 in the triple-drug group. At the time of analysis, median follow-up was 48 months (IQR 31-60). The cumulative incidence of grade 2-4 acute GVHD at day 100 was lower in the triple-drug group compared with the standard GVHD prophylaxis group (26% [95% CI 17-35] in the triple-drug group vs 52% [41-63] in the standard group; HR 0·45 [95% CI 0·28-0·73]; p=0·0013). After 1 and 4 years, non-relapse mortality increased to 4% (95% CI 0-9) and 16% (8-24) in the triple-drug group and 16% (8-24) and 32% (21-43) in the standard group (HR 0·48 [0·26-0·90]; p=0·021). Overall survival at 1 year was 86% (95% CI 78-93) in the triple-drug group and 70% in the standard group (60-80) and at 4 years it was 64% in the triple-drug group (54-75) and 46% in the standard group (34-57%; HR 0·62 [0·40-0·97]; p=0·035). Progression-free survival at 1 year was 77% (95% CI 68-85) in the triple-drug group and 64% (53-74) in the standard drug group, and at 4 years it was 59% in the triple-drug group (49-70) and 41% in the standard group (30-53%; HR 0·64 [0·42-0·99]; p=0·045). We observed no difference in the cumulative incidence of grade 3-4 acute GVHD (2% [0-5] in the triple-drug group vs 8% [2-14] in the standard group; HR 0·55 [0·16-1·96]; p=0·36) and chronic GVHD (49% [39-59] in triple-drug group vs 50% [39-61] in the standard group; HR 0·94 [0·62-1·40]; p=0·74). In both groups the most common CTCAE grade 4 or higher toxic effects were pulmonary.

INTERPRETATION

Adding sirolimus to cyclosporine and mycophenolate mofetil resulted in a significantly lower proportion of patients developing acute GVHD compared with patients treated with cyclosporine and mycophenolate mofetil alone. Based on these results, the combination of cyclosporine, mycophenolate mofetil, and sirolimus has become the new standard GVHD prophylaxis regimen for patients treated with non-myeloablative conditioning and HLA-matched unrelated HSCT at the Fred Hutchinson Cancer Research Center.

FUNDING

National Institutes of Health.

Allogeneic Stem Cell Transplantation and Chimeric Antigen Receptor (CAR) T-Cell Therapy for the Treatment of Non-Hodgkin Lymphoma

Despite the myriad of available treatments, a substantial subset of patients with non-Hodgkin lymphoma are not able to achieve a prolonged disease-free interval with conventional chemotherapy or targeted agents. For these patients, hematopoietic stem cell transplantation remains an option for consolidative or curative treatment. Additionally, chimeric antigen receptor T-cell therapy has emerged for patients with relapsed/refractory B-cell lymphomas. Published studies vary widely in their selected approach to transplant and cellular therapies. This review summarizes available data related to allogeneic hematopoietic stem cell transplantation and chimeric antigen receptor T-cell therapy for the treatment of non-Hodgkin lymphomas.

Long-term efficacy of anti-PD1 therapy in Hodgkin lymphoma with and without allogenic stem cell transplantation

INTRODUCTION

Long-term efficacy of anti-PD1 therapy and the need for a consolidation with allogenic haematopoietic stem cell transplantation (allo-HSCT) remain unclear in patients with relapsed/refractory (R/R) Hodgkin lymphoma (HL).

METHODS

We retrospectively analysed 78 patients with R/R HL treated with nivolumab in the French Early Access Program and compared their outcomes according to subsequent allo-HSCT.

RESULTS

After a median follow-up of 34.3 months, the best overall response rate was 65.8%, including 38.2% complete responses (CRs). The median progression-free survival (PFS) was 12.1 months. Patients reaching a CR upon nivolumab had a significantly longer PFS than those reaching a partial response (PR) (median = not reached vs 9.3 months, p < 0.001). In our cohort, 13 patients who responded (i.e. in CR or PR) to nivolumab monotherapy underwent consolidation with allo-HSCT. Among responding patients, none of those who underwent subsequent allo-HSCT (N = 13) relapsed, whereas 62.2% of those who were not consolidated with allo-HSCT (N = 37) relapsed (p < 0.001). There was no difference in overall survival (OS) between the two groups. Five of 6 patients who were not in CR at the time of transplantation (4 PRs and 1 progressive disease) converted into a CR after allo-HSCT.

CONCLUSION

Most patients with R/R HL treated with anti-PD1 monotherapy eventually progressed, notably those who did not achieve a CR. Patients undergoing consolidation with allo-HSCT after anti-PD1 therapy experienced prolonged disease-free survival compared with non-transplanted patients, but this difference did not translate into a benefit in OS. This information should be considered when evaluating the risk/benefit ratio of allo-HSCT after anti-PD1 therapy.

Antithymocyte globulin for graft-versus-host disease prophylaxis: an updated systematic review and meta-analysis

Graft-versus-host disease (GVHD) remains a limiting factor for successful allogeneic hematopoietic cell transplantation (allo-HCT). Conflicting data exist on the benefit of ATG on post-transplant survival. We performed a systematic review of randomized controlled trials (RCTs) to assess benefits and harms of thymoglobulin and Fresenius (re-branded as Grafalon) ATG formulations in patients undergoing allo-HCT for a variety of hematologic malignancies and bone marrow failure syndromes. A comprehensive search of MEDLINE, EMBASE, and Cochrane Library was performed. Data on methodological quality, benefits, and harms were extracted for each trial and pooled under a random-effects model. Eight RCTs (1134 patients) met the inclusion criteria. Methodological quality ranged from moderate to very low. Pooled results showed no difference in overall survival (OS) with the use of ATG (hazard ratio (HR) = 0.97; 95% confidence interval (CI) = 0.74-1.28; P = 0.83). ATG reduced grade II/III acute GVHD (risk ratio (RR) = 0.61; 95% CI = 0.48-0.77; P < 0.0001), grade III/IV acute GVHD (RR = 0.52; 95% CI = 0.34-0.81; P = 0.004), and chronic GVHD (RR = 0.52; 95% CI = 0.40-0.69; P < 0.00001) without an increase in non-relapse mortality (NRM) (RR = 0.91; 95% CI = 0.74-1.13; P = 0.40). Future studies with better methodological quality are needed to provide conclusive answers related to optimal dosing and timing of ATG for prevention of GVHD.

Outcomes of Patients with Recurrent and Refractory Lymphoma Undergoing Allogeneic Hematopoietic Cell Transplantation with BEAM Conditioning and Sirolimus- and Tacrolimus-Based GVHD Prophylaxis

The current standard of care for patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) is high-dose conditioning followed by autologous stem cell transplantation (ASCT). For some patients (ie, those with highest-risk disease, insufficient stem cell numbers after mobilization, or bone marrow involvement) allogeneic hematopoietic cell transplantation (alloHCT) offers the potential for cure. However, the majority of patients undergoing alloHCT receive reduced-intensity conditioning as a preparative regimen, and studies assessing outcomes of patients after alloHCT with myeloablative conditioning are limited. In this retrospective study, we reviewed outcomes of 22 patients with recurrent and refractory NHL who underwent alloHCT with myeloablative BEAM conditioning and received tacrolimus/sirolimus as graft-versus-host disease (GVHD) prophylaxis at City of Hope between 2005 and 2018. With a median follow-up of 2.6 years (range, 1.0 to 11.2 years), the probabilities of 2-year overall survival and event-free survival were 58.3% (95% confidence interval [CI], 35.0% to 75.8%) and 45.5% (95% CI, 24.4% to 64.3%), respectively. The cumulative incidence of grade II to IV acute GVHD was 45.5% (95% CI, 23.8% to 64.9%), with only 1 patient developing grade IV acute GVHD. However, chronic GVHD was seen in 55% of the patients (n = 12). Of the 22 eligible patients, 2 had undergone previous ASCT and 2 had undergone previous alloHCT. Both patients with previous ASCT developed severe regimen-related toxicity. Patients who underwent alloHCT with chemorefractory disease had lower survival rates, with 1-year OS and EFS of 44.4% and 33.0%, respectively. In conclusion, alloHCT with a BEAM preparative regimen and tacrolimus/sirolimus-based GVHD should be considered as an alternative option for patients with highest-risk lymphoma whose outcomes are expectedly poor after ASCT.

Upper gastrointestinal acute graft-versus-host disease adds minimal prognostic value in isolation or with other graft-versus-host disease symptoms as currently diagnosed and treated

Upper gastrointestinal acute graft-versus-host disease is reported in approximately 30% of hematopoietic stem cell transplant recipients developing acute graft-versus-host disease. Currently classified as Grade II in consensus criteria, upper gastrointestinal acute graft-versus-host disease is often treated with systemic immunosuppression. We reviewed the Center for International Blood and Marrow Transplant Research database to assess the prognostic implications of upper gastrointestinal acute graft-versus-host disease in isolation or with other acute graft-versus-host disease manifestations. 8567 adult recipients of myeloablative allogeneic hematopoietic stem cell transplant receiving T-cell replete grafts for acute leukemia, chronic myeloid leukemia or myelodysplastic syndrome between 2000 and 2012 were analyzed. 51% of transplants were from unrelated donors. Reported upper gastrointestinal acute graft-versus-host disease incidence was 12.1%; 2.7% of recipients had isolated upper gastrointestinal acute graft-versus-host disease, of whom 95% received systemic steroids. Patients with isolated upper gastrointestinal involvement had similar survival, disease-free survival, transplant-related mortality, and relapse as patients with Grades 0, I, or II acute graft-versus-host disease. Unrelated donor recipients with isolated upper gastrointestinal acute graft-versus-host disease had less subsequent chronic graft-versus-host disease than those with Grades I or II disease (P=0.016 and P=0.0004, respectively). Upper gastrointestinal involvement added no significant prognostic information when present in addition to other manifestations of Grades I or II acute graft-versus-host disease. If upper gastrointestinal symptoms were reclassified as Grade 0 or I, 425 of 2083 patients (20.4%) with Grade II disease would be downgraded, potentially impacting the interpretation of clinical trial outcomes. Defining upper gastrointestinal acute graft-versus-host disease as a Grade II entity, as it is currently diagnosed and treated, is not strongly supported by this analysis. The general approach to diagnosis, treatment and grading of upper gastrointestinal symptoms and their impact on subsequent acute graft-versus-host disease therapy warrants reevaluation.

Venetoclax for Treating Chronic Lymphocytic Leukaemia: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

Venetoclax is licensed to treat relapsed or refractory (R/R) chronic lymphocytic leukaemia (CLL). As part of the Single Technology Appraisal (STA) ID944, the National Institute for Health and Care Excellence (NICE) invited AbbVie, the manufacturer, to submit evidence on the use of venetoclax, within its licensed indication. The Evidence Review Group (ERG), Warwick Evidence, was asked to provide an independent and critical review of the submitted evidence. Evidence came from three single-arm trials in CLL patients with or without 17p deletion [del(17p])/TP53 chromosomal abnormalities. The anticipated licensed indication specified that venetoclax-eligible del(17p)/TP53 patients should have not responded to, or be deemed unsuitable for, B-cell receptor inhibitor (BCRi) therapy, and that non-del(17p)/TP53 patients should have not responded to both chemoimmunotherapy and BCRi therapy. The three trials were heterogeneous in terms of both del(17p)/TP53 status and previous exposure to BCRi therapy. The M13-982 study investigated 158 R/R CLL patients with the 17p deletion, but only a small number had received previous BCRi therapy; the M12-175 study investigated 67 patients with CLL or small lymphocytic lymphoma, some with the 17p deletion, but very few previously treated with BCRi therapy; and the M14-032 study included 105 patients previously treated with BCRi therapy (either idelalisib or ibrutinib), some of whom had unknown mutation status. The ERG concluded that the study populations did not directly conform to those specified in the licensed indication or in the NICE scope. Outcomes reported included overall response rate (ORR), duration of response, progression-free survival (PFS) and overall survival (OS); adverse events were reported for the pooled population of all three studies, as well as separately for each study. The median PFS was 41.4 and 27.2 months among patients in the M12-175 and M13-982 trials, respectively, whereas the median PFS was not reached in the M14-032 trial. Some results were designated academic in confidence and cannot be reported here. The submission provided a de novo partitioned survival cost-effectiveness model with three health states: pre-progression, post-progression and dead. Transition probabilities between health states were estimated using Weibull models for PFS and OS. The ERG judged the model structure to be appropriate. Venetoclax was compared with best supportive care (BSC) in patients with or without del(17p)/TP53 mutation status, and with palliative care (PC). To populate the del(17p)/TP53 venetoclax arm, the submission pooled del(17p)/TP53 patients from all three studies and fitted Weibull models for PFS and OS. PFS and OS models for non-del(17p)/TP53 venetoclax patients were obtained by applying hazard ratios (HRs) to the del(17p)/TP53 OS and PFS models, derived using Cox's regression analysis comparing del(17p)/TP53 and non-del(17p)/TP53 patients pooled from the M14-032 and M12-175 studies. The ERG expressed reservations about the company's pooling procedure, but acknowledged its expedience given the small evidence base. For the BSC comparator arm, the submission used the rituximab + placebo arm from a randomised controlled trial comparing idelalisib + rituximab versus placebo + rituximab ('study 116'). Weibull regression data for OS and PFS were taken from the idelalisib STA (ID764) submitted by Gilead to NICE. The ERG considered the use of the study 116 rituximab arm to be inconsistent with the licensed indication for venetoclax because these patients had neither not responded to nor were inappropriate for BCRi therapy, being eligible to be randomised to idelalisib. Another difficulty was the requirement for a technical correction in survival analysis because of considerable switching from rituximab to idelalisib. The ERG considered that post-progression survival of patients from the idelalisib arm of study 116 provided a more appropriate representation of BSC since these patients had not responded to BCRi therapy, consistent with venetoclax's licensed indication. For PC, the company submission used data from the UK CLL Forum. The company's base-case analysis indicated that venetoclax was clinically effective, but the resulting incremental cost-effectiveness ratios (ICERs) for del(17p)/TP53 (£39,940/quality-adjusted life-year [QALY] gained) and non-del(17p)/TP53 (£47,370/QALY gained) patients were well above the NICE threshold of £20,000-30,000/QALY. The ERG identified two errors in the implementation of the company's parametric models-one related to the implementation of HRs, and the other to the derivation of the Weibull shape parameters obtained from the Gilead idelalisib submission. The ERG made plausible adjustments to the company's base-case and corrected errors, resulting in a reduced estimate of the cost effectiveness of venetoclax in non-del(17p)/TP53 and del(17p)/TP53 indications; in the ERG's preferred base case, using post-progression survival of patients in the idelalisib arm of study 116 as the BSC comparator, deterministic ICERs were higher than the company's base-case for both indications: £57,476/QALY gained for del(17p)/TP53 and £77,779/QALY gained for non-del(17p)/TP53. The NICE Appraisal Committee's preliminary recommendation was that venetoclax used within its licensed indication should not be recommended for use in the National Health Service (NHS). In response to the preliminary recommendation, the company submitted new analyses; however, at a subsequent appraisal committee meeting, the original recommendation was upheld and the committee concluded there were large uncertainties around the clinical effectiveness of venetoclax and BSC, and that under the committee's preferred assumptions, the ICERs were higher than those generally considered cost effective, even when end-of-life criteria were taken into account. The company submitted further evidence, and the final guidance recommended venetoclax for use with the Cancer Drugs Fund for the two populations in this technology appraisal.

SupplAzithromycin for Prevention of Graft-Versus-Host Disease: A Randomized Placebo-Controlled Trial

Background: Allogeneic hematopoietic stem cell transplantation has been used widely to treat various types of malignant and non-malignant disorders. Graft-versus-host disease is one of the main complications of this procedure which is associated with considerable mortality and affects quality of life. Despite careful selection of HLA-matched donors and implementing immunosuppressive therapy, the incidence rate of graft-versus-host disease remains high. Macrolide antibiotics are well-known immunomodulatory agents and have been effective as prophylaxis for graft-versus-host disease in preclinical studies. Materials and Methods: Ninety-six adult patients with acute leukemia were recruited into a double-blind, randomized, placebo-controlled trial. All patients were first-time transplant candidates for a full-matched related or unrelated donor. Patients were allocated to receive azithromycin 500 mg daily (n=48) or placebo (n=48) from day -6 to +12. All patients received high-dose chemotherapy, standard immunosuppressive regimen and supportive care according to institutional protocols. Results: The incidence of acute graft-versus-host disease grade III-IV and chronic graft-versus-host disease garde I-III was not significantly different between the two study arms. Oral mucositis grade 1-3 occurred in significantly lower number of patients in the azithromycin group compared with placebo. Conclusion: Based on the results of this study, protective effect of azithromycin on graft-versus-host disease could not be demonstrated.

Dynamical system modeling to simulate donor T cell response to whole exome sequencing-derived recipient peptides: Understanding randomness in alloreactivity incidence following stem cell transplantation

Quantitative relationship between the magnitude of variation in minor histocompatibility antigens (mHA) and graft versus host disease (GVHD) pathophysiology in stem cell transplant (SCT) donor-recipient pairs (DRP) is not established. In order to elucidate this relationship, whole exome sequencing (WES) was performed on 27 HLA matched related (MRD), & 50 unrelated donors (URD), to identify nonsynonymous single nucleotide polymorphisms (SNPs). An average 2,463 SNPs were identified in MRD, and 4,287 in URD DRP (p<0.01); resulting peptide antigens that may be presented on HLA class I molecules in each DRP were derived in silico (NetMHCpan ver2.0) and the tissue expression of proteins these were derived from determined (GTex). MRD DRP had an average 3,670 HLA-binding-alloreactive peptides, putative mHA (pmHA) with an IC50 of <500 nM, and URD, had 5,386 (p<0.01). To simulate an alloreactive donor cytotoxic T cell response, the array of pmHA in each patient was considered as an operator matrix modifying a hypothetical cytotoxic T cell clonal vector matrix; each responding T cell clone’s proliferation was determined by the logistic equation of growth, accounting for HLA binding affinity and tissue expression of each alloreactive peptide. The resulting simulated organ-specific alloreactive T cell clonal growth revealed marked variability, with the T cell count differences spanning orders of magnitude between different DRP. Despite an estimated, uniform set of constants used in the model for all DRP, and a heterogeneously treated group of patients, higher total and organ-specific T cell counts were associated with cumulative incidence of moderate to severe GVHD in recipients. In conclusion, exome wide sequence differences and the variable alloreactive peptide binding to HLA in each DRP yields a large range of possible alloreactive donor T cell responses. Our findings also help understand the apparent randomness observed in the development of alloimmune responses.

Immune Checkpoint Blockade and Hematopoietic Stem Cell Transplant

Allogeneic hematopoietic stem cell transplant (HSCT) relies primarily upon graft-versus-tumor activity for cancer eradication. Relapse remains the principal cause of treatment failure after HSCT, implying frequent immune escape, which in at least some cases, appears to be mediated by increased expression of inhibitory immune checkpoints. In an attempt to restore anti-tumor immunity, checkpoint blockade therapy (CBT) targeting PD-1 and CLTA-4 has been used in conjunction with both allogeneic and autologous HSCT. Clinical experience in this setting is limited to several small clinical trials and case series, but together they suggest that treatment with CBT can effectively amplify anti-tumor immune responses. However, intrinsic to its mechanism is also the risk that CBT in the HSCT setting may also cause significant immune toxicity. Fatal immune-related adverse events and graft-versus-host disease have been observed, but in most cases, immune side effects appear to be reversible with steroids and CBT discontinuation. As clinical investigation continues, improved understanding of immune checkpoint biology will be critical to optimize safe and efficacious treatment strategies.

Predictors of overall survival among patients treated with sirolimus/tacrolimus vs methotrexate/tacrolimus for GvHD prevention

Sirolimus (SIR)/tacrolimus (TAC) is an alternative to methotrexate (MTX)/TAC. However, rational selection among these GvHD prophylaxis approaches to optimize survival of individual patients is not possible based on current evidence. We compared SIR/TAC (n=293) to MTX/TAC (n=414). The primary objective was to identify unique predictors of overall survival (OS). Secondary objective was to compare acute and chronic GvHD, relapse, non-relapse mortality, thrombotic microangiopathy (TMA), hepatic veno-occlusive disease (VOD/SOS), and acute kidney injury. Day 100 grades II-IV acute GvHD was significantly reduced in SIR/TAC vs MTX/TAC group (63 vs 73%, P=0.02). An interaction between GvHD prophylaxis groups and comorbidity index (hematopoietic cell transplantation (HCT)-CI) significantly impacted OS. Patients with HCT-CI⩾4 had significantly worse OS with MTX/TAC (HR 1.86, 95% CI 1.14-3.04, P=0.01) while no such effect was seen for SIR/TAC (HR 0.78, 95% CI 0.48-1.26, P=0.31). Other end points did not significantly differ between groups except TMA and VOD/SOS were increased in the SIR/TAC group, but excess death from these complications was not observed. We conclude, GvHD prophylaxis approach of SIR/TAC is associated with reduced grades II-IV acute GvHD, comparable toxicity profile to MTX/TAC, and improved OS among patients with HCT-CI⩾4.

Allogeneic hematopoietic stem cell transplantation for non-Hodgkin's lymphomas: a retrospective analysis of 77 cases

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a therapeutic option for relapsed, advanced, and otherwise incurable non-Hodgkin's lymphomas (NHL) suggested by the existence of a graft-versus-lymphoma effect. The main complications are graft-versus-host disease and infections. We performed a retrospective analysis of patients with NHL, who received an allo-SCT between January 1995 and December 2014. The parameters that had an impact on overall survival were age ≤60 years old, chemosensitive disease pre-allo-SCT, and indolent NHL histology. The parameters that had an impact on progression-free survival were age ≤60 years old and chemosensitive disease pre-allo-SCT. Only aggressive NHL histology and refractory disease pre-allo-SCT showed an increased risk of death in the multivariate model. The use of allo-SCT for young patients with multiple relapsed chemosensitive indolent NHL is a suitable option. Despite poor prognosis, young aggressive NHL patients can be considered for allo-SCT provided they have chemosensitive disease.

Safety and efficacy of allogeneic hematopoietic stem cell transplant after PD-1 blockade in relapsed/refractory lymphoma

Anti-programmed cell death protein 1 (PD-1) monoclonal antibodies are being increasingly tested in patients with advanced lymphoma. Following treatment, many of those patients are likely to be candidates for allogeneic hematopoietic stem cell transplant (HSCT). However, the safety and efficacy of HSCT may be affected by prior PD-1 blockade. We conducted an international retrospective analysis of 39 patients with lymphoma who received prior treatment with a PD-1 inhibitor, at a median time of 62 days (7-260) before HSCT. After a median follow-up of 12 months, the 1-year cumulative incidences of grade 2-4 and grade 3-4 acute graft-versus-host disease (GVHD) were 44% and 23%, respectively, whereas the 1-year incidence of chronic GVHD was 41%. There were 4 treatment-related deaths (1 from hepatic sinusoidal obstruction syndrome, 3 from early acute GVHD). In addition, 7 patients developed a noninfectious febrile syndrome shortly after transplant requiring prolonged courses of steroids. One-year overall and progression-free survival rates were 89% (95% confidence interval [CI], 74-96) and 76% (95% CI, 56-87), respectively. One-year cumulative incidences of relapse and nonrelapse mortality were 14% (95% CI, 4-29) and 11% (95% CI, 3-23), respectively. Circulating lymphocyte subsets were analyzed in 17 patients. Compared with controls, patients previously treated with PD-1 blockade had significantly decreased PD-1⁺ T cells and decreased ratios of T-regulatory cells to conventional CD4 and CD8 T cells. In conclusion, HSCT after PD-1 blockade appears feasible with a low rate of relapse. However, there may be an increased risk of early immune toxicity, which could reflect long-lasting immune alterations triggered by prior PD-1 blockade.

New perspectives on the use of mTOR inhibitors in allogeneic haematopoietic stem cell transplantation and graft-versus-host disease

Inhibition of the mechanistic target of rapamycin (mTOR) has been exploited largely both in solid tumour oncology and solid organ transplantation. More recently mTOR inhibitors such as sirolimus and everolimus have been introduced to the field of allogeneic haematopoietic stem cell transplantation where their unique combination of immunosuppressive purposes offering reduced nephrotoxicity and potential antimalignant effects reflect a unique drug profile that has led to their widespread use in both prophylaxis and therapy of graft-versus-host disease (GVHD). On the other hand haematological insufficiency, infectious complications as well as vasculopathies, have been frequently reported as limiting toxicities. Here, we review both the retrospective and prospective experience available to date and stress the need for prospective registration trials to reduce off label use and improve patient safety by optimizing dosing and enhancing pharmacovigilance. Furthermore, we speculate on the future role of mTOR inhibitors in allogeneic haematopoietic stem cell transplantation.

Next-generation sequencing-based detection of circulating tumour DNA After allogeneic stem cell transplantation for lymphoma

Next-generation sequencing (NGS)-based circulating tumour DNA (ctDNA) detection is a promising monitoring tool for lymphoid malignancies. We evaluated whether the presence of ctDNA was associated with outcome after allogeneic haematopoietic stem cell transplantation (HSCT) in lymphoma patients. We studied 88 patients drawn from a phase 3 clinical trial of reduced-intensity conditioning HSCT in lymphoma. Conventional restaging and collection of peripheral blood samples occurred at pre-specified time points before and after HSCT and were assayed for ctDNA by sequencing of the immunoglobulin or T-cell receptor genes. Tumour clonotypes were identified in 87% of patients with adequate tumour samples. Sixteen of 19 (84%) patients with disease progression after HSCT had detectable ctDNA prior to progression at a median of 3·7 months prior to relapse/progression. Patients with detectable ctDNA 3 months after HSCT had inferior progression-free survival (PFS) (2-year PFS 58% vs. 84% in ctDNA-negative patients, P = 0·033). In multivariate models, detectable ctDNA was associated with increased risk of progression/death (Hazard ratio 3·9, P = 0·003) and increased risk of relapse/progression (Hazard ratio 10·8, P = 0·0006). Detectable ctDNA is associated with an increased risk of relapse/progression, but further validation studies are necessary to confirm these findings and determine the clinical utility of NGS-based minimal residual disease monitoring in lymphoma patients after HSCT.

Sirolimus and Mycophenolate Mofetil as Calcineurin Inhibitor-Free Graft-versus-Host Disease Prophylaxis for Reduced-Intensity Conditioning Umbilical Cord Blood Transplantation

The use of calcineurin inhibitors (CNIs) to reduce the risk of graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT) requires intensive post-transplantation toxicity monitoring. Sirolimus-based GVHD prophylaxis is associated with a favorable toxicity profile and requires less intensive monitoring. However, the efficacy of sirolimus-based regimen compared with CNI-based regimen has not been evaluated in the setting of reduced-intensity conditioning (RIC) double umbilical cord blood (UCB) HCT. We compared outcomes of patients receiving sirolimus/mycophenolate mofetil (MMF) (n = 37) or cyclosporine (CSA)/MMF (n = 123) in an ongoing phase II study of RIC UCB transplantation. In multiple regression analysis, sirolimus/MMF did not influence the risk of grades II to IV or grades III and IV acute GVHD. In addition, there was no association between type of GVHD prophylaxis and hematopoietic engraftment. Infection density analysis found a significantly lower risk of infections with sirolimus/MMF between days +46 and +180 after HCT compared with CSA/MMF (3.4 versus 6.3 per 1000 patient-days, P = .03); however, no difference was observed before day +45. Sirolimus/MMF use resulted in no thrombotic microangiopathy, fewer instances of elevated serum creatinine >2 mg/dL (14% versus 45%; P <.01), and similar rates of sinusoidal obstruction syndrome (2.7% versus 4%; P = .68), compared with CSA/MMF. Disease-free survival at 1 year was 51% for sirolimus/MMF and 41% for CSA/MMF (P = .41), and sirolimus/MMF use did not influence the risk of nonrelapse mortality or survival. In conclusion, sirolimus/MMF GVHD prophylaxis was better tolerated and resulted in similar rates of GVHD and survival as compared to CSA/MMF after RIC double UCB transplantation.

Fludarabine/Busulfan versus Fludarabine/Melphalan Conditioning in Patients Undergoing Reduced-Intensity Conditioning Hematopoietic Stem Cell Transplantation for Lymphoma

There is at present little data to guide the choice of conditioning for patients with lymphoma undergoing reduced-intensity conditioning (RIC) allogeneic stem cell transplantation (SCT). In this study, we compared the outcomes of patients undergoing RIC SCT who received fludarabine and melphalan (FluMel), the standard RIC regimen used by the Spanish Group of Transplantation, and fludarabine and busulfan (FluBu), the standard RIC regimen used by the Dana-Farber Cancer Institute/Brigham and Women's Hospital. We analyzed 136 patients undergoing RIC SCT for lymphoma with either FluBu (n = 61) or FluMel (n = 75) conditioning between 2007 and 2014. Median follow-up was 36 months. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) was 13% with FluBu and 36% with FluMel (P = .002). The cumulative incidence of nonrelapse mortality (NRM) at 1 year was 3.3% with FluBu and 31% with FluMel (P < .0001). The cumulative incidence of relapse at 1 year was 29% with FluBu and 10% with FluMel (P = .08). The 3-year disease-free survival rate was 47% with FluBu and 36% with FluMel (P = .24), and the 3-year overall survival rate was 62% with FluBu and 48% with FluMel (P = .01). In multivariable analysis, FluMel was associated with a higher risk of acute grades II to IV GVHD (HR, 7.45; 95% CI, 2.30 to 24.17; P = .001) and higher risk of NRM (HR, 4.87; 95% CI, 1.36 to 17.44; P = .015). The type of conditioning was not significantly associated with relapse or disease-free survival in multivariable models. However, conditioning regimen was the only factor significantly associated with overall survival: FluMel conditioning was associated with a hazard ratio for death of 2.78 (95% CI, 1.23 to 6.27; P = .014) compared with FluBu. In conclusion, the use of FluBu as conditioning for patients undergoing SCT for lymphoma was associated with a lower risk of acute GVHD and NRM and improved overall survival when compared with FluMel in our retrospective study. These results confirm the differences between these RIC regimens in terms of toxicity and efficacy and support the need for comparative prospective studies.

A randomized phase II trial of tacrolimus, mycophenolate mofetil and sirolimus after non-myeloablative unrelated donor transplantation

The study is a randomized phase II trial investigating graft-versus-host disease prophylaxis after non-myeloablative (90 mg/m(2) fludarabine and 2 Gy total body irradiation) human leukocyte antigen matched unrelated donor transplantation. Patients were randomized as follows: arm 1 - tacrolimus 180 days and mycophenolate mofetil 95 days (n=69); arm 2 - tacrolimus 150 days and mycophenolate mofetil 180 days (n=71); arm 3 - tacrolimus 150 days, mycophenolate mofetil 180 days and sirolimus 80 days (n=68). All patients had sustained engraftment. Grade II-IV acute graft-versus-host disease rates in the 3 arms were 64%, 48% and 47% at Day 150, respectively (arm 3 vs. arm 1 (hazard ratio 0.62; P=0.04). Owing to the decreased incidence of acute graft-versus-host disease, systemic steroid use was lower at Day 150 in arm 3 (32% vs. 55% in arm 1 and 49% in arm 2; overall P=0.009 by hazard ratio analysis). The Day 150 incidence of cytomegalovirus reactivation was lower in arm 3 (arm 1, 54%; arm 2, 47%; arm 3, 22%; overall P=0.002 by hazard ratio analysis). Non-relapse mortality was comparable in the three arms at two years (arm 1, 26%; arm 2, 23%; arm 3, 18%). Toxicity rates and other outcome measures were similar between the three arms. The addition of sirolimus to tacrolimus and mycophenolate mofetil is safe and associated with lower incidence of acute graft-versus-host disease and cytomegalovirus reactivation. (clinicaltrials.gov identifier: 00105001).