Biomaterial Strategies for Selective Immune Tolerance: Advances and Gaps

Autoimmunity and allergies affect a large number of people across the globe. Current approaches to these diseases target cell types and pathways that drive disease, but these approaches are not cures and cannot differentiate between healthy cells and disease-causing cells. New immunotherapies that induce potent and selective antigen-specific tolerance is a transformative goal of emerging treatments for autoimmunity and serious allergies. These approaches offer the potential of halting-or even reversing-disease, without immunosuppressive side effects. However, translating successful induction of tolerance to patients is unsuccessful. Biomaterials offer strategies to direct and maximize immunological mechanisms of tolerance through unique capabilities such as codelivery of small molecules or signaling molecules, controlling signal density in key immune tissues, and targeting. While a growing body of work in this area demonstrates success in preclinical animal models, these therapies are only recently being evaluated in human trials. This review will highlight the most recent advances in the use of materials to achieve antigen-specific tolerance and provide commentary on the current state of the clinical development of these technologies.

Roles of the Dynamic Tumor Immune Microenvironment in the Individualized Treatment of Advanced Clear Cell Renal Cell Carcinoma

Immune checkpoint inhibitors (ICIs) are currently a first-line treatment option for clear cell renal cell carcinoma (ccRCC). However, recent clinical studies have shown that a large number of patients do not respond to ICIs. Moreover, only a few patients achieve a stable and durable response even with combination therapy based on ICIs. Available studies have concluded that the response to immunotherapy and targeted therapy in patients with ccRCC is affected by the tumor immune microenvironment (TIME), which can be manipulated by targeted therapy and tumor genomic characteristics. Therefore, an in-depth understanding of the dynamic nature of the TIME is important for improving the efficacy of immunotherapy or combination therapy in patients with advanced ccRCC. Here, we explore the possible mechanisms by which the TIME affects the efficacy of immunotherapy and targeted therapy, as well as the factors that drive dynamic changes in the TIME in ccRCC, including the immunomodulatory effect of targeted therapy and genomic changes. We also describe the progress on novel therapeutic modalities for advanced ccRCC based on the TIME. Overall, this review provides valuable information on the optimization of combination therapy and development of individualized therapy for advanced ccRCC.

Oral mucositis after tacrolimus/sirolimus or cyclosporine/methotrexate as graft-versus-host disease prophylaxis

OBJECTIVES

To determine whether treatment with tacrolimus plus sirolimus (Tac/Sir) as a prophylaxis for graft-versus-host disease worsens severe oral mucositis and delays healing compared to cyclosporine plus methotrexate (CsA/Mtx) following haematopoietic stem cell transplantation.

SUBJECTS AND METHODS

The study comprised 141 patients: 73 randomized to receive Tac/Sir and 68 to receive CsA/Mtx. The oral mucositis assessment scale and toxicity grading according to WHO were used to assess the severity, peak and duration of oral mucositis from the day -3 to day 24 post-transplant.

RESULTS

Eighty-seven patients developed oral mucositis in the first 24 days post-transplant. No significant difference in oral mucositis severity between the Tac/Sir and CsA/Mtx groups was observed. The peak oral mucositis score occurred on day 10 in both groups. Although oral mucositis scores had returned to baseline in the CsA/Mtx group on day 24 post-transplant, no significant difference compared with the Tac/Sir group was found.

CONCLUSIONS

The introduction of tacrolimus/sirolimus as a graft-versus-host disease prophylaxis in haematopoietic stem cell transplantation increased neither the incidence nor severity of oral mucositis compared with cyclosporine/methotrexate. Furthermore, oral mucositis healing was not prolonged and followed the same time pattern as cyclosporine/methotrexate.

Modulation of the immune response in rheumatoid arthritis with strategically released rapamycin

Rheumatoid arthritis (RA) is a chronic inflammatory disease, which is associated with symptoms, including synovial membrane inflammatory pain, joint synovitis and stiffness. However, there are no effective methods available to cure this disease. In the present study, rapamycin was used to modulate immunity in RA. To limit the cytotoxicity of rapamycin, rapamycin was loaded into well-characterized biocompatible nanoparticles. In vitro, rapamycin particles downregulated the activation of dendritic cell surface markers, including CD80⁺ and CD40⁺, upon interacting with macrophages. The rapamycin particles reduced the secretion of inflammatory cytokines, including interleukin (IL)-6, tumor necrosis factor (TNF) and IL-1β, which are characteristic of RA. In vivo, the rapamycin particles decreased the symptoms of RA in mice, and the production of inflammatory cytokines was associated with the occurrence of RA. The present study partially revealed the interactions between rapamycin and two types of immune cell in RA disease, and may potentially offer a solution to improve the treatment of RA.

A prospective randomized trial comparing cyclosporine/methotrexate and tacrolimus/sirolimus as graft-versus-host disease prophylaxis after allogeneic hematopoietic stem cell transplantation

Improvement of graft-versus-host disease prophylaxis remains an important goal in allogeneic hematopoietic stem cell transplantation. Based on reports of possibly preferential properties of sirolimus, we compared the standard regimen of cyclosporine and methotrexate (n=106) with a combination of tacrolimus and sirolimus (n=103) as graft-versus-host disease prophylaxis after allogeneic hematopoietic stem cell transplantation in a prospective, open, randomized trial. The hypothesis was that the tacrolimus/sirolimus regimen would lead to less acute graft-versus-host disease and reduced transplant-related mortality. There was no significant difference in the cumulative incidence of acute graft-versus-host disease of grades II-IV (41% vs. 51%; P=0.19) or grades III-IV (13% vs. 7%; P=0.09) between the groups. Time to neutrophil engraftment (18 days vs. 17 days; P=0.24) was similar, but time to platelet engraftment was longer in cyclosporine/methotrexate patients (14 vs. 12 days; P<0.01). No significant differences in incidence of oropharyngeal mucositis, time to full donor chimerism, or number of cytomegalovirus infections were seen between the two treatment arms, and transplant-related toxicities were equally distributed. Triglyceride (P=0.005) and cholesterol (P=0.009) levels were higher in tacrolimus/sirolimus patients. Transplant-related mortality (18% vs. 12%; P=0.40) and 5-year overall survival (72% vs. 71%; P=0.71) were similar. Five-year relapse-free survival in patients with malignant diagnoses was 65% in the cyclosporine/methotrexate group and 63% in the tacrolimus/sirolimus group (P=0.73). We conclude that tacrolimus/sirolimus remains a valid and safe alternative to cyclosporine/methotrexate as graft-versus-host disease prophylaxis after allogeneic hematopoietic stem cell transplantation, with comparable transplant-related outcomes. The trial was registered at clinicaltrials.gov identifier: 00993343.

Clinical presentation and management of mTOR inhibitor-associated stomatitis

Anti-cancer agents that inhibit the mTOR pathway are associated with a number of unique toxicities, with one of the most significant and potentially dose-limiting being stomatitis. The objective of this study was to report the clinical features and management outcomes of a series of cancer patients who developed painful mTOR inhibitor-associated stomatitis (mIAS). Seventeen cancer patients developed mIAS while being treated with everolimus- or ridaforolimus-containing protocols at the Dana-Farber Cancer Institute and were referred to the oral medicine clinic for evaluation and management. Clinical characteristics, toxicity management, and outcomes were summarized. In addition, the frequency and rationale for dose reductions and therapy discontinuation were assessed. The median duration of mTOR inhibitor therapy was 80 days (range 9-187 days). The median time to development of mouth ulcers was 10 days (range 4-25 days). Five patients required protocol-directed dose reductions due to grades 2 and 3 stomatitis and one patient discontinued cancer treatment due to mouth ulcers. Clinical improvement and pain relief was reported in 86.6% of patients following topical, intralesional, or systemic corticosteroid therapy, with side effects limited to secondary candidiasis (n=2). Mouth ulcers are a common and potentially dose limiting toxicity associated with the use of mTOR inhibitors in cancer treatment. This case series demonstrates that local and systemic corticosteroid therapy is an effective approach to managing patients with symptomatic mIAS. Prospective studies are necessary to evaluate the effectiveness of treatment and prevention strategies with the ultimate goal of improving overall cancer treatment outcomes.

Everolimus: an update on the mechanism of action, pharmacokinetics and recent clinical trials

BACKGROUND

A growing body of evidence suggests that everolimus might offer effective immunosuppressive activity together with antiproliferative effects that may address some of the unmet needs in the long-term therapeutic management of the post-transplant patient.

OBJECTIVE

To summarize the emerging evidence for employing everolimus-based immunosuppression.

METHODS

A systematic review was conducted of the Medline, Embase and Renal Health Library (Cochrane Collaboration) databases, and of the summary publications from international transplant meetings and congresses during 2000-2008.

RESULTS

This article summarizes this analysis, with special focus on the pharmacokinetic characteristics of everolimus and on the results of its use in renal transplantation. Some data has also been included about the efficacy of the drug in other solid organ transplantation and in tumours.

CONCLUSIONS

Everolimus is an immunosuppressant drug with proven efficacy in transplantation. When used in combination with cyclosporin, better results are obtained in renal function with low cyclosporin doses. Adverse events related to this drug are frequent and lead to moderate dropout rates.