Treatment with bortezomib of human CD4+ T cells preserves natural regulatory T cells and allows the emergence of a distinct suppressor T-cell population

PI3K inhibitors in chronic lymphocytic leukemia: where do we go from here?

Phosphatidylinositol 3-kinase (PI3K) inhibitors are effective in chronic lymphocytic leukemia (CLL). However, the severe toxicity profile associated with the first-generation inhibitors idelalisib and duvelisib, combined with the availability of other more tolerable agents, have limited their use. CLL is still considered incurable, and relapse after treatment, development of resistance, and treatment intolerance are common. It is therefore of interest to optimize the administration of currently approved PI3K inhibitors and to develop next-generation agents to improve tolerability, so that this class of agents will be considered an effective and safe treatment option when needed. These efforts are reflected in the large number of emerging clinical trials with PI3K inhibitors in CLL. Current strategies to overcome treatment limitations include intermittent dosing, which is established for copanlisib and zandelisib and under investigation for duvelisib and parsaclisib. A second strategy is to combine the PI3K inhibitor with another novel agent, either as a continuous regimen or a fixedduration regimen, to deepen responses. In addition to these approaches, it is of interest to identify higher-resolution actionable biomarkers that can predict treatment responses and toxicity, and inform personalized treatment decisions. Here, we discuss the current status of PI3K inhibitors in CLL, factors limiting the use of currently approved PI3K inhibitors in CLL, current strategies to overcome these limitations, and where to go next.

Updates in chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) is the leading cause of late morbidity and mortality after allogeneic hematopoietic cell transplantation. Symptoms and manifestations of chronic GVHD are heterogeneous and pleomorphic, and there are no standard treatments beyond corticosteroids. Therapy is typically prolonged, and chronic GVHD and its treatment are associated with adverse effects that have a significant impact on long-term quality of life and functional status. Several advances have been made over the last 2 decades to define the diagnosis of chronic GVHD as well as its severity and response criteria for clinical trials. Further understanding into the biologic mechanisms of the development of chronic GVHD has led to the investigation of several novel immunomodulatory and targeted therapies. Multi-institutional collaboration and pharmaceutical support in the development of therapies based on sound biologic mechanisms and clinical trials with defined end points and responses have led to several promising agents on the horizon of approval for treatment of chronic GVHD. This article reviews advances in our knowledge of chronic GVHD and its biologic framework to improve approaches to prevention and treatment.

Regulatory T-Cells and Multiple Myeloma: Implications in Tumor Immune Biology and Treatment

Multiple myeloma (MM) is associated with both cellular and humoral immune deficiencies and, despite significant advances in treatment, remains an incurable disease. Regulatory T-cells (Tregs) represent a critical subset of CD4 T-cells, characterized by CD4 + CD25+ Forkhead box P3+ (FoxP3+) phenotype, able to control peripheral tolerance and responses to foreign and tumor antigens. Tregs are elevated in various types of cancer, including hematological malignancies; in MM, data regarding Tregs function and numbers and their correlation with survival parameters are controversial. Advances in cancer biology have shown that the tumor microenvironment plays an important role in tumor progression. In MM, the highly immunosuppressive nature of the bone marrow microenvironment has been significantly elucidated in the past decade and it is now well acknowledged that targeting only the tumor clone may not be able to cure MM. Tregs within the tumor microenvironment might play a significant role in the suppression of antitumor immune responses against cancer cells and are considered to predict poor outcome in cancer patients; nonetheless the exact prognostic significance of this cell subpopulation in malignancies is still a matter of debate. In this review, we discuss the role of Tregs as an essential cell population of the MM immune microenvironment.

Delayed administration of ixazomib modifies the immune response and prevents chronic graft-versus-host disease

In this study, we aimed to modify the immune response in the long term after allogeneic bone marrow transplantation (allo-BMT) by using the proteasome inhibitor ixazomib (IXZ) at the late stages of the post-transplant period. This approach facilitated the immune reconstitution after transplantation. IXZ significantly prolonged survival and decreased the risk of chronic graft-versus-host disease (cGvHD) in two different murine models without hampering the graft-versus-leukemia (GvL) effect, as confirmed by bioluminescence assays. Remarkably, the use of IXZ was related to an increase of regulatory T cells both in peripheral blood and in the GvHD target organs and a decrease of effector donor T cells. Regarding B cells, IXZ treated mice had faster recovery of B cells in PB and of pre-pro-B cells in the bone marrow. Mice receiving ixazomib had a lower number of neutrophils in the GvHD target organs as compared to the vehicle group. In summary, delayed administration of IXZ ameliorated cGvHD while preserving GvL and promoted a pro-tolerogenic immune response after allo-BMT.

The Impact of Induction Regimes on Immune Responses in Patients with Multiple Myeloma

Current standard frontline therapy for newly diagnosed patients with multiple myeloma (NDMM) involves induction therapy, autologous stem cell transplantation (ASCT), and maintenance therapy. Major efforts are underway to understand the biological and the clinical impacts of each stage of the treatment protocols on overall survival statistics. The most routinely used drugs in the pre-ASCT "induction" regime have different mechanisms of action and are employed either as monotherapies or in various combinations. Aside from their direct effects on cancer cell mortality, these drugs are also known to have varying effects on immune cell functionality. The question remains as to how induction therapy impacts post-ASCT immune reconstitution and anti-tumor immune responses. This review provides an update on the known immune effects of melphalan, dexamethasone, lenalidomide, and bortezomib commonly used in the induction phase of MM therapy. By analyzing the actions of each individual drug on the immune system, we suggest it might be possible to leverage their effects to rationally devise more effective induction regimes. Given the genetic heterogeneity between myeloma patients, it may also be possible to identify subgroups of patients for whom particular induction drug combinations would be more appropriate.

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.

Complication from Desensitization

Sensitization to human leukocyte antigens (HLAs) has been one of the major clinical challenges for successful kidney transplantation. In end-stage renal disease, kidney transplantation provides benefits compared with dialysis in terms of improved patient survival better quality of life, and lower ongoing costs after the first year. Living donor kidney transplantation has an advantage with improved allograft survival, and performed earlier and electively compared with deceased donor transplantation. However sensitized patients are increasing in number on transplant waiting lists, and their prospect of getting a transplant is less than nonsensitized patients due to immunological incompatibility with the donor. Strategy for sensitized patients are listing for a compatible deceased donor transplant or, if they have a living donor, either selecting a kidney exchange program or undergoing a desensitization procedure. Desensitization procedures may be undertaken to increase access to either living or deceased donor transplants, and in some situations may also be employed to facilitate participation in a kidney exchange, in less immunological barrier to be overcome. The question of whether individuals are better off with a desensitization treatment followed by HLA-incompatible living donor transplantation or waiting on the deceased donor kidney transplant list for a compatible transplant has recently been addressed by two large multicenter studies, with conflicting results. A multicenter study from the United States published in the New England Journal of Medicine [365;318 326.2011] concluded that there was a strong survival benefit for sensitized patients undergoing desensitization followed by HLA-incompatible living donor kidney transplant compared with those remaining on the waiting list. Of interest, a second study, published in the Lancet, [389;727 734.2017] found no significant survival advantage for desensitized patients compared with similar patients remaining on the waiting list in the United Kingdom. Controversies still remain regarding how desensitization can be achieved and which techniques are effective and safe.

In this chapter various complications from the desensitization will be dealt with in current use of medications or armamentum.

Efficacy of bortezomib to intensify the conditioning regimen and the graft-versus-host disease prophylaxis for high-risk myeloma patients undergoing transplantation

This multicenter phase I trial was designed to evaluate the safety and efficacy of bortezomib (Bz) as part of both the conditioning regimen and the graft-versus-host disease (GvHD) prophylaxis. Patients received fludarabine, melphalan and Bz (days -9 and -2). GVHD prophylaxis consisted of Bz (days +1, +4, and +7), sirolimus (Siro) from day -5 and tacrolimus (Tk) from -3 (except the first five patients that did not receive Tk). Twenty-five patients with poor prognostic multiple myeloma were included. Eleven out of the 19 patients had high-risk features. Out of the 21 patients evaluable at day +100, 14 were in CR (67%) and 7 (33%) in PR. Cumulative incidence (CI) of nonrelapse mortality at 1 year was 24%. CI of grades 2-4 and 3-4 acute GvHD was 35% and 10%, respectively; CI of chronic GvHD was 35% and 55% at 1 and 2 years, respectively. Overall and event free survival at 2 years were 64% and 31%, respectively. Bz as part of the conditioning regimen and in the combination with Siro/tacrolimus for GvHD prophylaxis is safe and effective allowing an optimal disease control early after transplant and reducing the risk of GvHD.

The combination of ionizing radiation and proteasomal inhibition by bortezomib enhances the expression of NKG2D ligands in multiple myeloma cells

Bortezomib, which is a potent proteasome inhibitor, has been used as a first-line drugs to treat multiple myeloma for a few decades, and radiotherapy has frequently been applied to manage acute bone lesions in the patients. Therefore, it was necessary to investigate what the benefits might be if the two therapies were applied simultaneously in the treatment of multiple myeloma. Since it was known that radiotherapy and proteasome inhibitors could increase the expression of NKG2D ligands through induction of protein synthesis and suppression of protein degradation of NKG2D ligands, respectively, we supposed that the combined treatment might further enhance the expression of NKG2D ligands. In this study, we analyzed the expression level of NKG2D ligands using multiplex PCR and flow cytometry after treatment of IM-9 and RPMI-8226 myeloma cells with bortezomib and ionizing radiation; we then assayed the susceptibility to NK-92 cells. Although the expression of only some kinds of NKG2D ligands were increased by treatment with bortezomib alone, five kinds of NKG2D ligands that we assayed were further induced at the surface protein level after combined treatment with ionizing radiation and bortezomib. Furthermore, combined treatment made myeloma cells more susceptible to NK-92 cells, compared with treatment with bortezomib alone. In conclusion, the combination therapy of ionizing radiation plus the proteasome inhibitor bortezomib is a promising therapeutical strategy for enhancing NK cell-mediated anticancer immune responses.

Calcineurin and mTOR Inhibitor-Free Post-Transplantation Cyclophosphamide and Bortezomib Combination for Graft-versus-Host Disease Prevention after Peripheral Blood Allogeneic Hematopoietic Stem Cell Transplantation: A Phase I/II Study

Graft-versus-host disease (GVHD) hampers the utility of allogeneic hematopoietic stem cell transplantation (AHSCT). The purpose of this study was to determine the feasibility, safety, and efficacy of a novel combination of post-transplantation cyclophosphamide (PTC) and bortezomib for the prevention of GVHD. Patients undergoing peripheral blood AHSCT for hematological malignancies after reduced-intensity conditioning with grafts from HLA-matched related or unrelated donors were enrolled in a phase I/II clinical trial. Patients received a fixed dose of PTC and an increasing dose of bortezomib in 3 cohorts, from .7 to 1 and then to 1.3 mg/m², administered 6 hours after graft infusion and 72 hours thereafter, during phase I. The study was then extended at the higher dose in phase II for a total of 28 patients. No graft failure and no unexpected grade ≥3 nonhematologic toxicities were encountered. The median times to neutrophil and platelet engraftment were 16 and 27 days, respectively. Day +100 treatment-related mortality was 3.6% (95% confidence interval [CI], .2% to 15.7%). The cumulative incidences of grades II to IV and grades III and IV acute GVHD were 35.9% (95% CI, 18.6% to 53.6%) and 11.7% (95% CI, 2.8% to 27.5%), respectively. The incidence of chronic GVHD was 27% (95% CI, 11.4% to 45.3%). Progression-free survival, overall survival, and GVHD and relapse-free survival rates were 50% (95% CI, 30.6% to 66.6%), 50.8% (95% CI, 30.1% to 68.2%), and 37.7% (95% CI, 20.1% to 55.3%), respectively. Immune reconstitution, measured by CD3, CD4, and CD8 recovery, was prompt. The combination of PTC and bortezomib for the prevention of GVHD is feasible, safe, and yields promising results. The combination warrants further examination in a multi-institutional trial.

Bortezomib augments lymphocyte stimulatory cytokine signaling in the tumor microenvironment to sustain CD8+T cell antitumor function

Tumor-induced immune tolerance poses a major challenge for therapeutic interventions aimed to manage cancer. We explored approaches to overcome T-cell suppression in murine breast and kidney adenocarcinomas, and lung fibrosarcoma expressing immunogenic antigens. We observed that treatment with a reversible proteasome inhibitor bortezomib (1 mg/kg body weight) in tumor-bearing mice significantly enhanced the expression of lymphocyte-stimulatory cytokines IL-2, IL-12, and IL-15. Notably, bortezomib administration reduced pulmonary nodules of mammary adenocarcinoma 4T1.2 expressing hemagglutinin (HA) model antigen (4T1HA) in mice. Neutralization of IL-12 and IL-15 cytokines with a regimen of blocking antibodies pre- and post-adoptive transfer of low-avidity HA518-526-specific CD8+T-cells following intravenous injection of 4T1HA cells increased the number of pulmonary tumor nodules. This neutralization effect was counteracted by the tumor metastasis-suppressing action of bortezomib treatments. In bortezomib-treated 4T1HA tumor-bearing mice, CD4+T-cells showed increased IL-2 production, CD11c+ dendritic cells showed increased IL-12 and IL-15 production, and HA-specific activated CD8+T-cells showed enhanced expression of IFNγ, granzyme-B and transcription factor eomesodermin. We also noted a trend of increased expression of IL-2, IL-12 and IL-15 receptors as well as increased phosphorylation of STAT5 in tumor-infiltrating CD8+T-cells following bortezomib treatment. Furthermore, bortezomib-treated CD8+T-cells showed increased phosphorylation of mitogen-activated protein kinase p38, and Akt, which was abrogated by phosphatidylinositide 3-kinase (PI3K) inhibitor. These data support the therapeutic potential of bortezomib in conjunction with other immunotherapies to augment the strength of convergent signals from CD8+T-cell signaling molecules including TCR, cytokine receptors and downstream PI3K/Akt/STAT5 pathways to sustain CD8+T-cell effector function in the tumor microenvironment.

Post-Transplantation Cyclophosphamide and Ixazomib Combination Rescues Mice Subjected to Experimental Graft-versus-Host Disease and Is Superior to Either Agent Alone

Lapses in the prevention of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT) warrant novel approaches. Such approaches include, among others, the use of post-transplantation cyclophosphamide (PTC) and proteasome inhibitors. Although PTC alone consistently produces low rates of chronic GVHD, the incidence of acute GVHD remains significant. Inversely, prolonged post-transplantation administration of proteasome inhibitors carries a risk of paradoxical aggravation of GVHD. We examined whether the combination of cyclophosphamide and ixazomib addresses the limitations of each of these agents when used alone to prevent GVHD in mice subjected to allogeneic HSCT across MHC barriers. We chose ixazomib, an orally bioavailable proteasome inhibitor, because of its favorable physiochemical characteristics. The combination of cyclophosphamide and ixazomib improved overall survival of mice in comparison to an untreated control group and to groups receiving either cyclophosphamide alone or ixazomib alone. Furthermore, cyclophosphamide prevented the surge of IL-1β, GVHD aggravation, and sudden death associated with prolonged administration of ixazomib after HSCT. Finally, we demonstrated that although ixazomib was administered before cyclophosphamide, it did not impair the preferential depletion of proliferating as opposed to resting donor T cells. Our data suggest that the combination of cyclophosphamide and ixazomib for the prevention of GVHD after allogeneic HSCT is promising and merits further investigation in clinical trials.

Mechanistic approaches for the prevention and treatment of chronic GVHD

Clinical outcomes for patients undergoing allogeneic hematopoietic stem cell transplantation continue to improve, but chronic graft-versus-host disease (GVHD) remains a common toxicity and major cause of nonrelapse morbidity and mortality. Treatment of chronic GVHD has previously relied primarily on corticosteroids and other broadly immune suppressive agents. However, conventional immune suppressive agents have limited clinical efficacy in chronic GVHD, and prolonged immune suppressive treatments result in additional toxicities that further limit clinical recovery from transplant and return to normal daily function. Recent advances in our understanding of the immune pathology of chronic GVHD offer the possibility that new therapeutic approaches can be directed in more precise ways to target specific immunologic mechanisms and pathways. In this review, we briefly summarize current standard treatment options and present new therapeutic approaches that are supported by preclinical studies and early-phase clinical trials suggesting that these approaches may have clinical utility for treatment or prevention of chronic GVHD. Further evaluation of these new therapeutic options in well-designed prospective multicenter trials are needed to identify the most effective new agents and improve outcomes for patients with chronic GVHD.

Bortezomib for the prevention and treatment of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation is the standard treatment for a variety of benign and malignant conditions. However, graft-versus-host disease (GvHD) continues to present a major barrier to the success and wide applicability of this procedure. Although current GvHD prevention and treatment regimens exclusively target T cells, bortezomib, a reversible proteasome inhibitor, possesses unique immune regulatory activities that span a wide variety of cellular processes of T and dendritic cells essential for the development of GvHD. Herein, we review the current understanding of the effects of bortezomib in vitro and in animal models and summarize the clinical data relevant to its use in the prevention and treatment of GvHD. We conclude with an outline of the remaining challenges and opportunities to optimize bortezomib's potential role in this setting.

Drug-induced modulation of T lymphocytes as a potential mechanism of susceptibility to infections in patients with multiple myeloma during bortezomib therapy

Bortezomib is effective in the therapy of multiple myeloma (MM), but causes infections that are different from those associated with conventional chemotherapy. It is important to identify the risk factors that facilitate infections associated with bortezomib therapy. In the present report, we sought to (1) define the features of the infections associated with this therapy and (2) identify the immune mechanisms responsible for the observed susceptibility to these infections. We first retrospectively analyzed the clinical data of 143 patients who had received bortezomib therapy for MM. We then prospectively assessed the modulation of T lymphocyte status during this therapy, and evaluated potential relationships between infections and T lymphocyte changes. The infection rates peaked during the first cycle of bortezomib therapy (47.6 %) in patients with MM (p < 0.05 vs. subsequent cycles). Bortezomib therapy was associated with higher incidence rates of viral and fungal infections (15.8 %, p < 0.05 vs. conventional chemotherapy). In addition, patients with the IgG immunophenotype showed higher bacterial and viral infection rates (respectively, p = 0.008 and 0.009). The T lymphocyte numbers significantly decreased after bortezomib therapy (p < 0.05), and the same was true for the Th1/Th2 ratio (p < 0.01). Patients with MM who have decreased lymphocyte counts, while on bortezomib therapy are more likely to develop bacterial or viral infections. In addition, an imbalance in T lymphocyte subsets is also associated with bacterial or viral infections in these patients.

Evolving paradigms in the treatment of relapsed/refractory multiple myeloma: increased options and increased complexity

The use of modern therapies such as thalidomide, bortezomib and lenalidomide coupled with upfront high-dose therapy and autologous stem cell transplant (ASCT) has resulted in improved survival in patients with newly diagnosed multiple myeloma (MM). However, patients with relapsed/refractory multiple myeloma (RRMM) often have poorer clinical outcomes and might benefit from novel therapeutic strategies. Emerging therapies, such as deacetylase inhibitors, monoclonal antibodies and new proteasome inhibitors, appear promising and may change the therapeutic landscape in RRMM. A limited number of studies has shown a benefit with salvage ASCT in patients with RRMM, although there remains ongoing debate about its timing and effectiveness. Improvement in transplant outcomes has re-ignited a debate on the timing and possible role for salvage ASCT and allogeneic stem cell transplant in RRMM. As the treatment options for management of patients with RRMM become increasingly complex, physicians must consider both disease- and patient-related factors in choosing the appropriate therapeutic approach, with the goal of improving efficacy while minimizing toxicity.

Bortezomib in kidney transplantation

PURPOSE OF REVIEW

The purpose of this review is to evaluate the effectiveness of bortezomib in the recent literature for the prevention and treatment of kidney transplant rejection.

RECENT FINDINGS

Several studies have analyzed bortezomib alone and in comparison to more traditional immunosuppressive agents during the last 2 years. If administered prior to transplant or soon thereafter, bortezomib appears to lower donor-specific antibody levels and improves graft survival. Its role as a treatment option for antibody-mediated rejection after transplant remains unclear, with limited evidence supporting its long-term success.

SUMMARY

Bortezomib appears to be a promising early desensitizing agent in the world of kidney transplantation and high short-term success rates have been observed. However, additional randomized trials would be useful to more conclusively demonstrate its effectiveness and optimal administration time in relation to transplant surgery.

Modulatory effects of bortezomib on host immune cell functions

Bortezomib is an inhibitor of the ubiquitin-proteasome proteolytic pathway responsible for intracellular protein turnover. Cellular proteins controlled by this pathway represent a diverse group of potential therapeutic targets, particularly in cancer cells, which exploit this proteasomal pathway to promote their growth and diminish apoptosis. Along with inhibiting the proteasome and thus sensitizing tumor cells to apoptosis, bortezomib may also have multiple effects on the host immune responses. This review summarizes the effects that bortezomib may play on immune cell subsets in various disease states in modifying lymphocyte receptors, ligands, the expression of various cytokines and chemokines and their downstream signaling. We also propose steps that can be taken to refine combinatorial strategies that include bortezomib to improve current immunotherapeutic approaches.

Short Course of Post-Transplantation Cyclophosphamide and Bortezomib for Graft-versus-Host Disease Prevention after Allogeneic Peripheral Blood Stem Cell Transplantation Is Feasible and Yields Favorable Results: A Phase I Study

An effective graft-versus-host disease (GVHD) preventative approach that preserves the graft-versus-tumor effect after allogeneic hematopoietic stem cell transplantation (HSCT) remains elusive. Standard GVHD prophylactic regimens suppress T cells indiscriminately and are suboptimal. Conversely, post-transplantation high-dose cyclophosphamide selectively destroys proliferating alloreactive T cells, allows the expansion of regulatory T cells, and induces long-lasting clonal deletion of intrathymic antihost T cells. It has been successfully used to prevent GVHD after allogeneic HSCT. Bortezomib has antitumor activity on a variety of hematological malignancies and exhibits a number of favorable immunomodulatory effects that include inhibition of dendritic cells. Therefore, an approach that combines post-transplantation cyclophosphamide and bortezomib seems attractive. Herein, we report the results of a phase I study examining the feasibility and safety of high-dose post-transplantation cyclophosphamide in combination with bortezomib in patients undergoing allogeneic peripheral blood HSCT from matched siblings or unrelated donors after reduced-intensity conditioning. Cyclophosphamide was given at a fixed dose (50 mg/kg on days +3 and +4). Bortezomib dose was started at .7 mg/m2, escalated up to 1.3 mg/m2, and was administered on days 0 and +3. Patients receiving grafts from unrelated donors also received rabbit antithymocyte globulin. The combination was well tolerated and allowed prompt engraftment in all patients. The incidences of acute GVHD grades II to IV and grades III and IV were 20% and 6.7%, respectively. With a median follow-up of 9.1 months (range, 4.3 to 26.7), treatment-related mortality was 13.5% with predicted 2-year disease-free survival and overall survival of 55.7% and 68%, respectively. The study suggests that the combination of post-transplantation cyclophosphamide and bortezomib is feasible and may offer an effective and practical GVHD prophylactic regimen. The combination, therefore, merits further examination.

Therapeutic benefit of bortezomib on acute graft-versus-host disease is tissue specific and is associated with interleukin-6 levels

Bortezomib, a proteasome inhibitor capable of direct antitumor effects, has been shown to prevent acute graft-versus-host disease (GVHD) when administered in a short course immediately after bone marrow transplantation (BMT) in mice. However, when bortezomib is given continuously, CD4(+) T cell-mediated gastrointestinal tract damage increases GVHD mortality. To investigate the protective effects of bortezomib on other organs, we used a CD8-dependent acute GVHD (aGVHD) model of C3H.SW donor T cells engrafted into irradiated C57BL/6 recipients (minor MHC mismatch), which lack significant gut GVHD. Our data in this model show that bortezomib can be given continuously to prevent and treat aGVHD mediated by CD8(+) T cells, but this effect is organ specific, such that only skin, and not liver, protection was observed. Despite the lack of hepatic protection, bortezomib still significantly improved survival, primarily because of its skin protection. Reduced skin GVHD by bortezomib was correlated with reduced serum and skin IL-6 levels. Administration of a blocking IL-6 antibody in this model also resulted in similar cutaneous GVHD protection. These results indicate that bortezomib or blockade of IL-6 may prevent CD8(+) T cell-mediated cutaneous acute GVHD.

A phase II study of bortezomib plus prednisone for initial therapy of chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) induces significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Corticosteroids are standard initial therapy, despite limited efficacy and long-term toxicity. Based on our experience using bortezomib as effective acute GVHD prophylaxis, we hypothesized that proteasome-inhibition would complement the immunomodulatory effects of corticosteroids to improve outcomes in chronic GVHD (cGVHD). We undertook a single-arm phase II trial of bortezomib plus prednisone for initial therapy of cGVHD. Bortezomib was administered at 1.3 mg/m(2) i.v. on days 1, 8, 15, and 22 of each 35-day cycle for 3 cycles (15 weeks). Prednisone was dosed at .5 to 1 mg/kg/day, with a suggested taper after cycle 1. All 22 enrolled participants were evaluable for toxicity; 20 were evaluable for response. Bortezomib plus prednisone therapy was well tolerated, with 1 occurrence of grade 3 sensory peripheral neuropathy possibly related to bortezomib. The overall response rate at week 15 in evaluable participants was 80%, including 2 (10%) complete and 14 (70%) partial responses. The organ-specific complete response rate was 73% for skin, 53% for liver, 75% for gastrointestinal tract, and 33% for joint, muscle, or fascia involvement. The median prednisone dose decreased from 50 mg/day to 20 mg/day at week 15 (P < .001). The combination of bortezomib and prednisone for initial treatment of cGVHD is feasible and well tolerated. We observed a high response rate to combined bortezomib and prednisone therapy; however, in this single-arm study, we could not directly measure the impact of bortezomib. Proteasome inhibition may offer benefit in the treatment of cGVHD and should be further evaluated.

Proteasome inhibition with bortezomib depletes plasma cells and specific autoantibody production in primary thymic cell cultures from early-onset myasthenia gravis patients

Bortezomib is a potent inhibitor of proteasomes currently used to eliminate malignant plasma cells in multiple myeloma patients. It is also effective in depleting both alloreactive plasma cells in acute Ab-mediated transplant rejection and their autoreactive counterparts in animal models of lupus and myasthenia gravis (MG). In this study, we demonstrate that bortezomib at 10 nM or higher concentrations killed long-lived plasma cells in cultured thymus cells from nine early-onset MG patients and consistently halted their spontaneous production not only of autoantibodies against the acetylcholine receptor but also of total IgG. Surprisingly, lenalidomide and dexamethasone had little effect on plasma cells. After bortezomib treatment, they showed ultrastructural changes characteristic of endoplasmic reticulum stress after 8 h and were no longer detectable at 24 h. Bortezomib therefore appears promising for treating MG and possibly other Ab-mediated autoimmune or allergic disorders, especially when given in short courses at modest doses before the standard immunosuppressive drugs have taken effect.

Epigenetic modification of the FoxP3 TSDR in HAM/TSP decreases the functional suppression of Tregs

HTLV-1 is a human retrovirus that is associated with the neuroinflammatory disorder HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). In these patients, HTLV-1 is primarily found in the CD4(+)CD25(+) T cell subset (Regulatory T cells:Tregs), which is responsible for peripheral immune tolerance and is known to be dysfunctional in HAM/TSP. Recent evidence suggests that FoxP3 expression and function is determined epigenetically through DNA demethylation in the Treg-specific demethylated region (TSDR). We analyzed the methylation of the TSDR in PBMCs, CD4(+) T cells, and CD4(+)CD25(+) T cells from normal healthy donors (NDs) and HAM/TSP patients. We demonstrated that there is decreased demethylation in analyzed PBMCs and CD4(+)CD25(+) T cells from HAM/TSP patients as compared to NDs. Furthermore, decreased TSDR demethylation was associated with decreased functional suppression by Tregs. Additionally, increased HTLV-1 Tax expression in HAM/TSP PBMC culture correlated with a concomitant decline in FoxP3 TSDR demethylation. Overall, we suggest that HTLV-1 infection decreases Treg functional suppressive capacity in HAM/TSP through modification of FoxP3 TSDR demethylation and that dysregulated Treg function may contribute to HAM/TSP disease pathogenesis.

[Proteasomes on thyroid tissue allotransplantation under induction of donor specific tolerance in rats]

The proteasomes in the liver of August rats (RT1C) were investigated 30 days after the allotransplantation of Wistar rat (RT1u) thyroid tissue under renal capsule with/without induction of donor specific tolerance by donor splenocyte intraportal administration. The level of the total proteasome pool, immune proteasomes containing the LMP2 and/or LMP7 subunits, proteasome 19S- and 11S-regulators was defined. The intact and sham-operated August rats were used as control groups. The level of all immune proteasome forms and 11S regulator increased while the level of the total proteasome pool and 19S regulator decreased in the liver of experimental animals compared to the control groups that indicated changes of liver functional state after transplantation. The 19S/11S ratio increased in the liver of non-tolerated rats compared to tolerated animals. In the liver of tolerated rats with survived transplants, the quantity of mononuclear cells, expressing the immune subunit LMP2, greatly increased in comparison with control and non-tolerated animals. Study of the survived transplants showed the increase of the ratio of LMP2/LMP7 immune subunits and 19S/11S regulators in them compared to the tissue replacing the rejected transplants. In the control intact thyroid tissue, the immune proteasomes were almost not revealed, while 19S/11S ratio was maximal. Thus, the development of the immune reaction or its suppression is accompanied by change of the balance between different proteasome forms. The immune subunit LMP7 and 11S regulator are connected with the response against donor tissue. On the contrary, the immune subunit LMP2 and 19S regulator are likely to be important for the immune tolerance development and survived tissue functioning. The low content of the immune proteasomes in the follicle cells was found by immunofluorescence assay. The formation of antigens for major histocompatibility complex class I molecules was impaired by low immune proteasome content that led to immunological tolerance to hormone-producing follicle cells.

Phase II clinical trial for the evaluation of bortezomib within the reduced intensity conditioning regimen (RIC) and post-allogeneic transplantation for high-risk myeloma patients

The current study was designed to assess the safety and efficacy of bortezomib in combination with fludarabine and melphalan as reduced intensity conditioning before allogeneic stem cell transplantation in patients with high risk multiple myeloma. Sixteen patients were evaluable. The median number of previous line of treatment was 3; all patients had relapsed following a prior autograft and 13 had previously received bortezomib. Fifteen of them either remained stable or improved disease status at day +100 post-transplant, including 11 patients with active disease. More specifically, nine patients (56%) and five patients (31%) reached complete remission and partial response, respectively. 25% developed grade III acute graft-versus-host disease. The cumulative incidence of non-relapse mortality, relapse and overall survival were 25%, 54% and 41%, respectively, at 3 years. Regarding the non-haematological toxicity (grade>2), two patients developed peripheral neuropathy, two patients liver toxicity and 1 pulmonary toxicity early post-transplant. The haematological toxicity was only observed during the first three cycles mostly related to low haemoglobin and platelet levels. The current trial is the first one evaluating the safety and efficacy of bortezomib as part of a reduced intensity conditioning regimen among patients with high risk multiple myeloma.

Proteasome inhibitors as immunosuppressants: biological rationale and clinical experience

Accumulating evidence supports the potential of proteasome inhibitors as immunosuppressants. Proteasome inhibitors interfere with antigen processing and presentation, as well as with the signaling cascades involved in immune cell function and survival. Both myeloma and healthy plasma cells appear to be highly susceptible to proteasome inhibitors due to impaired proteasomal activity in both cell types. As a consequence, these agents can be used to reduce antibody production and thus prevent antibody-induced tissue damage. Several clinical studies have explored the potential of bortezomib, a peptide boronate proteasome inhibitor, for treating immune disorders, such as antibody-mediated organ rejection and graft-versus-host disease (GVHD), with encouraging results. Here, we discuss the biological rationale for the use of proteasome inhibitors as immunosuppressive agents and review the clinical experience with bortezomib in immune-mediated diseases.

The novel combination of sirolimus and bortezomib prevents graft-versus-host disease but maintains the graft-versus-leukemia effect after allogeneic transplantation

BACKGROUND

We have previously shown that bortezomib induces a depletion of alloreactive T cells and allows the expansion of T cells with suppressive properties. In the current study, we analyzed the potential synergistic effect of bortezomib in conjunction with sirolimus in order to reduce-graft-versus-host disease without hampering graft-versus-leukemia effect in the allogeneic transplant setting.

DESIGN AND METHODS

We evaluated the effect of sirolimus, bortezomib or the combination of both in the proliferation and activation of in vitro stimulated T lymphocytes. Pathways involved in this synergy were also analyzed using Western blot assays. Finally, BALB/c mice receiving C57BL/6 allogeneic donor bone marrow with splenocytes were used to measure in vivo the effect of this novel combination on the risk of graft-versus-host disease.

RESULTS

The combination of both drugs synergistically inhibited both activation and proliferation of stimulated T cells. Also, the production of Th1 cytokines (IFN γ, IL-2 and TNF) was significantly inhibited. This effect was due, at least in part, to the inhibition of Erk and Akt phosphorylation. In vivo, the combination reduced the risk of graft-versus-host disease without hampering graft-versus-leukemia effect, as shown in mice receiving graft-versus-host disease prophylaxis with sirolimus plus bortezomib being infused with tumor WEHI cells plus C57BL/6 donor BM and splenocytes.

CONCLUSIONS

The current study reveals a synergistic effect of the combination sirolimus and bortezomib to prevent graft-versus-host disease while maintaining the graft-versus-leukemia effect.

The secret ally: immunostimulation by anticancer drugs

It has recently become clear that the tumour microenvironment, and in particular the immune system, has a crucial role in modulating tumour progression and response to therapy. Indicators of an ongoing immune response, such as the composition of the intratumoural immune infiltrate, as well as polymorphisms in genes encoding immune modulators, have been correlated with therapeutic outcome. Moreover, several anticancer agents--including classical chemotherapeutics and targeted compounds--stimulate tumour-specific immune responses either by inducing the immunogenic death of tumour cells or by engaging immune effector mechanisms. Here, we discuss the molecular and cellular circuitries whereby cytotoxic agents can activate the immune system against cancer, and their therapeutic implications.

Proteasome inhibitors

In May 2003, the US Food and Drug Administration (FDA) granted accelerated approval for the use of the first-in-class proteasome inhibitor bortezomib as a third-line therapy in multiple myeloma, and the European Union followed suit a year later. Bortezomib has subsequently been approved for multiple myeloma as a second-line treatment on its own and as a first-line therapy in combination with an alkylating agent and a corticosteroid. Furthermore, bortezomib has also been approved as a second-line therapy for mantle cell lymphoma. In this chapter, the focus is on the current clinical research on bortezomib, its adverse effects, and the resistance of multiple myeloma patients to bortezomib-based therapy. The various applications of bortezomib in different diseases and recent advances in the development of a new generation of inhibitors that target the proteasome or other parts of the ubiquitin-proteasome system are also reviewed.

Role of T cell-nuclear factor κB in transplantation

Nuclear factor (NF) κB is a pleiotropic transcription factor that is ubiquitously expressed. After transplantation of solid organs, NF-κB in the graft is activated within a few hours as a consequence of ischemia/reperfusion and then again after a few days in intragraft infiltrating cells during the process of acute allograft rejection. In the present article, we review the components of the NF-κB pathway, their mechanisms of activation, and their role in T cell and antigen-presenting cell activation and differentiation and in solid organ allograft rejection. Targeted inhibition of NF-κB in selected cell types may promote graft survival with fewer adverse effects compared with global immunosuppressive therapies.

Next-generation insights into regulatory T cells: expression profiling and FoxP3 occupancy in Human

Regulatory T-cells (Treg) play an essential role in the negative regulation of immune answers by developing an attenuated cytokine response that allows suppressing proliferation and effector function of T-cells (CD4(+) Th). The transcription factor FoxP3 is responsible for the regulation of many genes involved in the Treg gene signature. Its ablation leads to severe immune deficiencies in human and mice. Recent developments in sequencing technologies have revolutionized the possibilities to gain insights into transcription factor binding by ChiP-seq and into transcriptome analysis by mRNA-seq. We combine FoxP3 ChiP-seq and mRNA-seq in order to understand the transcriptional differences between primary human CD4(+) T helper and regulatory T-cells, as well as to study the role of FoxP3 in generating those differences. We show, that mRNA-seq allows analyzing the transcriptomal landscape of T-cells including the expression of specific splice variants at much greater depth than previous approaches, whereas 50% of transcriptional regulation events have not been described before by using diverse array technologies. We discovered splicing patterns like the expression of a kinase-dead isoform of IRAK1 upon T-cell activation. The immunoproteasome is up-regulated in both Treg and CD4(+) Th cells upon activation, whereas the 'standard' proteasome is up-regulated in Tregs only upon activation.

Depletion of alloreactive T-cells in vitro using the proteasome inhibitor bortezomib preserves the immune response against pathogens

Current graft-versus-host disease (GVHD) inhibition approaches lead to abrogation of pathogen-specific T-cell responses. We propose an approach to inhibit GVHD without hampering immunity against pathogens: in vitro depletion of alloreactive T cells with the preoteasome inhibitor bortezomib. We show that PBMCs stimulated with allogeneic cells and treated with bortezomib greatly reduce their ability to produce IFN-γ when re-stimulated with the same allogeneic cells, but mainly preserve their ability to respond to citomegalovirus stimulation. Unlike in vivo administration of immunosuppressive drugs or other strategies of allodepletion, in vitro allodepletion with bortezomib maintains pathogen-specific T cells, representing a promising alternative for GVHD prophylaxis.

Management of the sensitized adult heart transplant candidate

Heart transplant recipients sensitized to human leukocyte antigens comprise a challenging subgroup of patients. Sensitization has been associated with a variety of effects that determine short-term and long-term outcomes. These include a higher rate of acute rejection and graft loss, and a heightened risk for developing cardiac allograft vasculopathy. Because of improvements in both tissue typing and immunomodulatory therapies coupled with the growing population receiving mechanical circulatory support/LVAD, the percent of sensitized patients listed for heart transplantation has increased, inflicting a greater burden to the already scarce donor pool. Despite these potentially adverse developments, pre-transplant immunologic management has resulted in decreased waiting times and outcomes that were not possible over 10 yr ago. The following review will focus on the contemporary management of the sensitized heart transplant candidate and highlight therapies that have allowed the successful transplantation of this growing and challenging patient population, including several approaches in development.

Immunosuppression in the sensitized heart transplant recipient

PURPOSE OF REVIEW

The proportion of heart transplant candidates who are allosensitized has increased over time. Advances in tissue typing and immunosuppression have improved the rate of successful transplant in this challenging population. Recently published data regarding contemporary approaches to desensitization prior to and immunosuppression following transplant are summarized.

RECENT FINDINGS

Continued progress in measurement and characterization of antibodies and strategies to abrogate antibody production both prior to and following heart transplant have been encouraging. Updates on the role of non-human leukocyte antigen antibodies and the impact of mechanical circulatory support on allosensitization are provided. Data on current desensitization strategies, including the increasing use of monoclonal antibodies, are provided and the potential role of complement inhibitors will be reviewed. Increasing experience with potent novel agents is likely to provide the opportunity to improve transplant outcomes for highly sensitized patients.

SUMMARY

Although allosensitized heart transplant candidates remain a management challenge, excellent outcomes can be achieved with contemporary approaches. Advances in the understanding of B-cell biology are anticipated to further broaden options and improve outcomes.

Novel agents to improve outcome of allogeneic transplantation for patients with multiple myeloma

Over the last few decades therapy for multiple myeloma has improved remarkably. In particular, the introduction of novel agents has allowed improved response rates prior to, and after, stem cell transplantation with extension of progression-free survival in high-risk patients. Nevertheless, most patients relapse, leaving multiple myeloma an incurable disease. Despite being the only treatment option that has real curative potential, allogeneic transplantation has not shown its superiority to autologous transplantation due to its high morbidity and mortality rates. This review highlights how novel agents might help to reduce treatment-related mortality and to improve tumor control prior to and post-allogeneic stem cell transplant, which will hopefully result in significantly improved long-term disease control, and maybe a cure following this treatment modality.

International Myeloma Working Group Consensus Statement Regarding the Current Status of Allogeneic Stem-Cell Transplantation for Multiple Myeloma

Purpose

To define consensus statement regarding allogeneic stem-cell transplantation (Allo-SCT) as a treatment option for multiple myeloma (MM) on behalf of International Myeloma Working Group.

Patients and Methods

In this review, results from prospective and retrospective studies of Allo-SCT in MM are summarized.

Results

Although the introduction of reduced-intensity conditioning (RIC) has lowered the high treatment-related mortality associated with myeloablative conditioning, convincing evidence is lacking that Allo-RIC improves the survival compared with autologous stem-cell transplantation.

Conclusion

New strategies are necessary to make Allo-SCT safer and more effective for patients with MM. Until this is achieved, Allo-RIC in myeloma should only be recommended in the context of clinical trials.

Bortezomib: a new player in pre- and post-transplant desensitization?

Several desensitization strategies have been investigated for the reversal of acute antibody-mediated rejection or for the removal of preformed anti-HLA antibodies, with the aim to promote access to renal transplantation. Today, their success appears limited or incomplete. Bortezomib, a selective inhibitor of the 26S proteasome, which is largely used in the treatment of multiple myeloma, could be a novel promising desensitizing agent. Its mechanism of action and preliminary clinical use in renal transplantation is reviewed here.

Role of allogeneic transplantation in multiple myeloma in the era of new drugs

High-dose melphalan with autologous stem cell rescue has been regarded as the standard of care for patients with newly diagnosed myeloma up to the age of 65–70 years. The recent development of agents with potent anti-tumor activity such as thalidomide, lenalidomide and bortezomib has further improved overall survival and response rates. However, relapse is a continuous risk.

Allografting is a potentially curative treatment for a subset of multiple myeloma patients for its well documented graft-vs-myeloma effects. However, its role has been hotly debated. Even though molecular remissions have been reported up to 50% after high-dose myeloablative conditionings, their applications, given the high toxicity, have been for long limited to younger relapsed/refractory patients. These limitations have greatly been reduced through the introduction of non-myeloablative/reduced-intensity conditionings.

The introduction of new drugs, characterised by low risks of early mortality, indeed requires to define role and timing of an allograft to capture the subset of patients who may most benefit from graft-vs-myeloma effects.

Ultimately, new drugs should not be viewed as mutually exclusive with an allograft. They may be employed to achieve profound cytoreduction before and enhance graft-versus-myeloma effects as consolidation/maintenance therapy after an allograft. However, this combination should be explored only in well-designed clinical trials.

Proteasome inhibition and allogeneic hematopoietic stem cell transplantation: a review

The proteasome and its associated ubiquitin protein modification system have proved to be an important therapeutic target in the treatment of multiple myeloma and other cancers. In addition to direct antitumor effects, proteasome inhibition also exerts strong effects on nonneoplastic immune cells. This indicates that proteasome inhibition, through the use of agents like bortezomib, could be used therapeutically to modulate immune responses. In this review we explore the emerging data, both preclinical and clinical, highlighting the importance of proteasome targeting of immunologic responses, primarily in the context of allogeneic hematopoietic stem cell transplantation (HSCT), both for the control of transplant-related toxicities like acute and chronic graft-versus-host disease (aGVHD, cGHVHD), and for improved malignant disease control after allogeneic HSCT.