The anti-CD40L monoclonal antibody AT-1501 promotes islet and kidney allograft survival and function in nonhuman primates

CAR Treg synergy with anti-CD154 promotes infectious tolerance and dictates allogeneic heart transplant acceptance

Successful allograft-specific tolerance induction would eliminate the need for daily immunosuppression and improve posttransplant quality of life. Adoptive cell therapy with regulatory T cells expressing donor-specific chimeric antigen receptors (CAR Tregs) is a promising strategy but, as monotherapy, cannot prolong survival with allografts with multiple MHC mismatches. Using an HLA-A2-transgenic haplo-mismatched heart transplantation model in immunocompetent C57BL/6 recipients, we showed that HLA-A2-specific CAR (A2.CAR) Tregs were able to synergize with a low dose of anti-CD154 to enhance graft survival. Using haplo-mismatched grafts expressing the 2W-OVA transgene and tetramer-based tracking of 2W- and OVA-specific T cells, we showed that in mice with accepted grafts, A2.CAR Tregs inhibited donor-specific T cell, B cell, and antibody responses and promoted a substantial increase in endogenous FOXP3+ Tregs with indirect donor specificity. By contrast, in mice where A2.CAR Tregs failed to prolong graft survival, FOXP3- A2.CAR T cells preferentially accumulated in rejecting allografts, and endogenous donor-specific responses were not controlled. This study therefore provides evidence for synergy between A2.CAR Tregs and CD154 blockade to promote infectious tolerance in immunocompetent recipients of haplo-mismatched heart grafts and defines features of A2.CAR Tregs when they fail to reshape host immunity toward allograft tolerance.

From Edmonton to Lantidra and beyond: immunoengineering islet transplantation to cure type 1 diabetes

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing β cells within pancreatic islets, the specialized endocrine cell clusters of the pancreas. Islet transplantation has emerged as a β cell replacement therapy, involving the infusion of cadaveric islets into a patient's liver through the portal vein. This procedure offers individuals with T1D the potential to restore glucose control, reducing or even eliminating the need for exogenous insulin therapy. However, it does not address the underlying autoimmune condition responsible for T1D. The need for systemic immunosuppression remains the primary barrier to making islet transplantation a more widespread therapy for patients with T1D. Here, we review recent progress in addressing the key limitations of islet transplantation as a viable treatment for T1D. Concerns over systemic immunosuppression arise from its potential to cause severe side effects, including opportunistic infections, malignancies, and toxicity to transplanted islets. Recognizing the risks, the Edmonton protocol (2000) marked a shift away from glucocorticoids to prevent β cell damage specifically. This transition led to the development of combination immunosuppressive therapies and the emergence of less toxic immunosuppressive and anti-inflammatory drugs. More recent advances in islet transplantation derive from islet encapsulation devices, biomaterial platforms releasing immunomodulatory compounds or surface-modified with immune regulating ligands, islet engineering and co-transplantation with accessory cells. While most of the highlighted studies in this review remain at the preclinical stage using mouse and non-human primate models, they hold significant potential for clinical translation if a transdisciplinary research approach is prioritized.

Islet Cell Replacement and Regeneration for Type 1 Diabetes: Current Developments and Future Prospects

Type 1 diabetes (T1D) is a chronic autoimmune disorder characterized by the destruction of insulin-producing beta cells in the pancreas, leading to insulin deficiency and chronic hyperglycemia. The main current therapeutic strategies for clinically overt T1D - primarily exogenous insulin administration combined with blood glucose monitoring - fail to fully mimic physiological insulin regulation, often resulting in suboptimal or insufficient glycemic control. Islet cell transplantation has emerged as a promising avenue for functionally replacing endogenous insulin production and achieving long-term glycemic stability. Here, we provide an overview of current islet replacement strategies, ranging from islet transplantation to stem cell-derived islet cell transplantation, and highlight emerging approaches such as immunoengineering. We examine the advancements in immunosuppressive protocols to enhance graft survival, innovative encapsulation, and immunomodulation techniques to protect transplanted islets, and the ongoing challenges in achieving durable and functional islet integration. Additionally, we discuss the latest clinical outcomes, the potential of gene editing technologies, and the emerging strategies for islet cell regeneration. This review aims to highlight the potential of these approaches to transform the management of T1D and improve the quality of life of individuals affected by this condition.

New Developments and Therapeutic Drug Monitoring Options in Costimulatory Blockade in Solid Organ Transplantation: A Systematic Critical Review

PURPOSE

In this review, the authors summarized the latest developments in costimulatory blockade to prevent rejection after solid organ transplantation (SOT) and discussed possibilities for future research and the need for therapeutic drug monitoring (TDM) of these agents.

METHODS

Studies about costimulatory blockers in SOT in humans or animal transplant models in the past decade (2014-2024) were systematically reviewed in PubMed, European Union clinical trials (EudraCT), and ClinicalTrials.gov .

RESULTS

Seventy-five registered clinical trials and 58 published articles were found on costimulation blockade of the CD28-CD80/86, CD40-CD40L, and OX40-OX40L pathways. Belatacept, an antagonist of the CD28-CD80/86 pathway, is the only approved costimulatory agent in SOT, hence accounting for most of the research. Other identified costimulatory blocking agents included abatacept and CD28 antagonists tegoprubart, dazodalibep, and TNX-1500. Although tegoprubart was unsuccessful in pancreas transplantation in nonhuman primates, trials in human kidney transplantation are underway. Dazodalibep trials faced recruitment challenges. TNX-1500 was unsuccessful in animal studies and is currently not pursued in humans. After discontinuation of iscalimab (CD40-CD154 pathway antagonist) in SOT, the alternatives, bleselumab and KPL404, showed promising results in kidney transplantation and cardiac xenotransplantation. Studies on secondary costimulatory pathway antagonists, such as OX40-OX40L, have only used animal models. Despite the low interindividual variability in pharmacokinetics (PK) in all studied agents, TDM could be useful for optimizing dosing in PK/pharmacodynamic (PD) studies.

CONCLUSIONS

The routine use of costimulation blockade in SOT is hindered by problems in efficacy compared with the standard of care. Costimulatory inhibitors could be combined in a calcineurin inhibitor-free regimen. Future PK/pharmacodynamic studies in costimulatory agents and personalized medicine could warrant TDM of these agents.

Transplantation of a genetically modified porcine heart into a live human

Following our previous experience with cardiac xenotransplantation of a genetically modified porcine heart into a live human, we sought to achieve improved results by selecting a healthier recipient and through more sensitive donor screening for potential zoonotic pathogens. Here we transplanted a 10-gene-edited pig heart into a 58-year-old man with progressive, debilitating inotrope-dependent heart failure due to ischemic cardiomyopathy who was not a candidate for standard advanced heart failure therapies. He was maintained on a costimulation (anti-CD40L, Tegoprubart) blockade-based immunomodulatory regimen. The xenograft initially functioned well, with excellent systolic and diastolic function during the first several weeks posttransplantation. Subsequently, the xenograft developed rapidly progressing diastolic heart failure, biventricular wall thickening and, ultimately, near-complete loss of systolic function necessitating initiation of extracorporeal membranous oxygenation on day 31. Given these setbacks, the patient chose to transition to comfort care after 40 days. As with our first patient, histology did not reveal substantial immune cell infiltration but suggested capillary endothelial injury with interstitial edema and early fibrosis. No evidence of porcine cytomegalovirus replication in the xenograft was observed. Strategies to overcome the obstacle of antibody-mediated rejection are needed to advance the field of xenotransplantation.

CD154 blockade effectively controls antibody-mediated rejection in highly sensitized nonhuman primate kidney transplant recipients

Current desensitization and maintenance immunosuppression regimens for kidney transplantation in sensitized individuals show limited ability to control the posttransplant humoral response, resulting in high rates of antibody-mediated rejection (ABMR) and graft failure. Here, we showed that anti-CD154 monoclonal antibody (mAb)-based immunosuppression more effectively controlled allograft rejection and humoral rebound in a highly sensitized nonhuman primate kidney transplantation model compared with tacrolimus-based standard-of-care (SOC) immunosuppression. Desensitization with an anti-CD154 mAb (5C8) and a proteasome inhibitor led to decreased donor-specific antibodies (DSAs) and disruption of lymph node germinal centers with reduction of proliferating, memory, and class-switched B cells as well as T follicular helper cells. After transplant, the nonhuman primates maintained on 5C8-based immunosuppression had significantly better survival compared with those maintained on SOC immunosuppression (135.2 days versus 32.8 days, P = 0.013). The 5C8-treated group demonstrated better suppression of DSAs after transplant, more robust suppression of B cell populations, and better induction of regulatory T cells. Fewer infectious and welfare complications, including viral reactivation and weight loss, were also observed with 5C8-based immunosuppression compared with SOC immunosuppression. Therefore, anti-CD154 mAbs may improve kidney transplant outcomes through better control of posttransplant immune responses. The superior efficacy of anti-CD154 mAb-based immunosuppression over tacrolimus-based SOC seen in this highly sensitized NHP transplant model suggests that anti-CD154 mAbs could potentially be used to desensitize and treat highly sensitized patients receiving kidney transplantation.

Harnessing cellular therapeutics for type 1 diabetes mellitus: progress, challenges, and the road ahead

Type 1 diabetes mellitus (T1DM) is a growing global health concern that affects approximately 8.5 million individuals worldwide. T1DM is characterized by an autoimmune destruction of pancreatic β cells, leading to a disruption in glucose homeostasis. Therapeutic intervention for T1DM requires a complex regimen of glycaemic monitoring and the administration of exogenous insulin to regulate blood glucose levels. Advances in continuous glucose monitoring and algorithm-driven insulin delivery devices have improved the quality of life of patients. Despite this, mimicking islet function and complex physiological feedback remains challenging. Pancreatic islet transplantation represents a potential functional cure for T1DM but is hindered by donor scarcity, variability in harvested cells, aggressive immunosuppressive regimens and suboptimal clinical outcomes. Current research is directed towards generating alternative cell sources, improving transplantation methods, and enhancing cell survival without chronic immunosuppression. This Review maps the progress in cell replacement therapies for T1DM and outlines the remaining challenges and future directions. We explore the state-of-the-art strategies for generating replenishable β cells, cell delivery technologies and local targeted immune modulation. Finally, we highlight relevant animal models and the regulatory aspects for advancing these technologies towards clinical deployment.

Biotechnology Revolution Shaping the Future of Diabetes Management

INTRODUCTION

Diabetes mellitus (DM) has a millennia-long history, with early references dating back to ancient Egypt and India. However, it was not until the 20th century that the connection between diabetes and insulin was fully understood. The sequencing of insulin in the 1950s initiated the convergence of biotechnology and diabetes management, leading to the development of recombinant human insulin in 1982. This marked the start of peptide-based therapies in DM. Recombinant peptides for DM treatment: Numerous recombinant peptides have been developed since, starting with modified insulin molecules, with the aim of bettering DM management through fine-tuning the glycemic response to insulin. Peptide-based therapies in DM have expanded substantially beyond insulin to include agonists of Glucagon-like peptide-1 receptor and Glucose-dependent insulinotropic polypeptide receptor, glucagon receptor antagonists, and even peptides exerting multiple receptor agonist effects, for better metabolic control. Insulin pumps, continuous glucose monitoring, and automated insulin delivery systems: The development of modern delivery systems combined with real-time glucose monitoring has significantly advanced diabetes care. Insulin pumps evolved from early large devices to modern sensor-augmented pumps with automated shutoff features and hybrid closed-loop systems, requiring minimal user input. The second-generation systems have demonstrated superior outcomes, proving highly effective in diabetes management. Islet cell transplantation, organoids, and biological pancreas augmentation represent innovative approaches to diabetes management. Islet cell transplantation aims to restore insulin production by transplanting donor beta cells, though challenges persist regarding graft survival and the need for immunosuppression. Organoids are a promising platform for generating insulin-producing cells, although far from clinical use. Biological pancreas augmentation relies on therapies that promote beta-cell (re)generation, reduce stress, and induce immune tolerance. Further biotechnology-driven perspectives in DM will include metabolic control via biotechnology-enabled tools such as custom-designed insulin hybrid molecules, machine-learning algorithms to control peptide release, and engineering cells for optimal peptide production and secretion.

Small-molecule inhibitors of the CD40-CD40L costimulatory interaction are effective in pancreatic islet transplantation and prevention of type 1 diabetes models

As part of our work to develop small-molecule inhibitors (SMIs) of the CD40-CD40L(CD154) costimulatory protein-protein interaction, here, we describe the ability of two of our most promising SMIs, DRI-C21041 and DRI-C21095, to prolong the survival and function of islet allografts in two murine models of islet transplantation (under the kidney capsule and in the anterior chamber of the eye) and to prevent autoimmune type 1 diabetes (T1D) onset in NOD mice. In both transplant models, a significant portion of islet allografts (50%-80%) remained intact and functional long after terminating treatment, suggesting the possibility of inducing operational immune tolerance via inhibition of the CD40-CD40L axis. SMI-treated mice maintained the structural integrity and function of their islet allografts with concomitant reduction in immune cell infiltration as evidenced by direct longitudinal imaging in situ. Furthermore, in female NODs, three-month SMI treatment reduced the incidence of diabetes from 80% to 60% (DRI-C21041) and 25% (DRI-C21095). These results (i) demonstrate the susceptibility of this TNF superfamily protein-protein interaction to small-molecule inhibition, (ii) confirm the in vivo therapeutic potential of these SMIs of a critical immune checkpoint, and (iii) reaffirm the therapeutic promise of CD40-CD40L blockade in islet transplantation and T1D prevention. Thus, CD40L-targeting SMIs could ultimately lead to alternative immunomodulatory therapeutics for transplant recipients and prevention of autoimmune diseases that are safer, less immunogenic, more controllable (shorter half-lives), and more patient-friendly (i.e., suitable for oral administration, which makes them easier to administer) than corresponding antibody-based interventions.

CAR Treg synergy with anti-CD154 mediates infectious tolerance to dictate heart transplant outcomes

Successful allograft specific tolerance induction would eliminate the need for daily immunosuppression and improve post-transplant quality of life. Adoptive cell therapy with regulatory T cells expressing donor-specific Chimeric Antigen Receptors (CAR-Tregs) is a promising strategy, but as monotherapy, cannot prolong the survival with allografts with multiple MHC mismatches. Using an HLA-A2-transgenic haplo-mismatched heart transplantation model in immunocompetent C57Bl/6 recipients, we show that HLA-A2-specific (A2) CAR Tregs was able to synergize with low dose of anti-CD154 to enhance graft survival. Using haplo-mismatched grafts expressing the 2W-OVA transgene and tetramer-based tracking of 2W- and OVA-specific T cells, we showed that in mice with accepted grafts, A2.CAR Tregs inhibited endogenous non-A2 donor- specific T cell, B cell and antibody responses, and promoted a significant increase in endogenous FoxP3 + Tregs with indirect donor-specificity. By contrast, in mice where A2.CAR Tregs failed to prolong graft survival, FoxP3 neg A2.CAR T cells preferentially accumulated in rejecting allografts and endogenous donor-specific responses were not controlled. This study therefore provides the first evidence for synergy between A2.CAR Tregs and CD154 blockade to promote infectious tolerance in immunocompetent recipients of haplo-mismatched heart grafts and defines features of A2.CAR Tregs when they fail to reshape host immunity towards allograft tolerance.

Iscalimab Combined With Transient Tesidolumab Prolongs Survival in Pig-to-Rhesus Monkey Renal Xenografts

OBJECTIVE

To evaluate the clinically relevant anti-CD40 antibody iscalimab for baseline immunosuppression in a preclinical pig-to-rhesus renal xenograft model.

SUMMARY BACKGROUND DATA

CD40/CD40L co-stimulation blockade-based immunosuppression has been more successful than calcineurin-based protocols in prolonging xenograft survival in preclinical models.

METHODS

GGTA1 knockout/CD55 transgenic pig kidneys were transplanted into rhesus monkeys (n = 6) receiving an iscalimab-based immunosuppressive regimen.

RESULTS

Two grafts were lost early (22 and 26 days) because of ectatic donor ureters with otherwise normal histology. The other recipients survived 171, 315, 422, and 439 days with good renal function throughout the posttransplant course. None of the recipients experienced serious infectious morbidity.

CONCLUSIONS

It may be reasonable to evaluate an iscalimab-based immunosuppressive regimen in clinical renal xenotransplantation.

New molecular targets in the treatment of rheumatoid arthritis

PURPOSE OF REVIEW

This review will discuss selected emerging molecular targets and associated potential therapeutic agents for rheumatoid arthritis (RA)-directed treatment.

RECENT FINDINGS

Agents in active development for RA treatment include those targeted to CD40 and CD40 ligand, programmed death protein 1 (PD-1), and granulocyte-macrophage colony-stimulating factor (GM-CSF). Several other molecules with a strong theoretical role in RA pathogenesis and/or demonstrated efficacy in other autoimmune diseases are also being evaluated as potential drug targets in preclinical or translational studies in RA. These targets include interleukin 1 receptor associated kinases 1 and 4 (IRAK1, IRAK4), tyrosine kinase 2 (Tyk2), bradykinin receptor 1 (B1R), OX40 and OX40 ligand.

SUMMARY

Identification of molecular targets for RA treatment remains an active area of investigation, with multiple therapeutic agents in clinical and preclinical development.

Innovations in bio-engineering and cell-based approaches to address immunological challenges in islet transplantation

Human allogeneic pancreatic islet transplantation is a life-changing treatment for patients with severe Type 1 Diabetes (T1D) who suffer from hypoglycemia unawareness and high risk of severe hypoglycemia. However, intensive immunosuppression is required to prevent immune rejection of the graft, that may in turn lead to undesirable side effects such as toxicity to the islet cells, kidney toxicity, occurrence of opportunistic infections, and malignancies. The shortage of cadaveric human islet donors further limits islet transplantation as a treatment option for widespread adoption. Alternatively, porcine islets have been considered as another source of insulin-secreting cells for transplantation in T1D patients, though xeno-transplants raise concerns over the risk of endogenous retrovirus transmission and immunological incompatibility. As a result, technological advancements have been made to protect transplanted islets from immune rejection and inflammation, ideally in the absence of chronic immunosuppression, to improve the outcomes and accessibility of allogeneic islet cell replacement therapies. These include the use of microencapsulation or macroencapsulation devices designed to provide an immunoprotective environment using a cell-impermeable layer, preventing immune cell attack of the transplanted cells. Other up and coming advancements are based on the use of stem cells as the starting source material for generating islet cells 'on-demand'. These starting stem cell sources include human induced pluripotent stem cells (hiPSCs) that have been genetically engineered to avoid the host immune response, curated HLA-selected donor hiPSCs that can be matched with recipients within a given population, and multipotent stem cells with natural immune privilege properties. These strategies are developed to provide an immune-evasive cell resource for allogeneic cell therapy. This review will summarize the immunological challenges facing islet transplantation and highlight recent bio-engineering and cell-based approaches aimed at avoiding immune rejection, to improve the accessibility of islet cell therapy and enhance treatment outcomes. Better understanding of the different approaches and their limitations can guide future research endeavors towards developing more comprehensive and targeted strategies for creating a more tolerogenic microenvironment, and improve the effectiveness and sustainability of islet transplantation to benefit more patients.

Hypoimmune islets achieve insulin independence after allogeneic transplantation in a fully immunocompetent non-human primate

Allogeneic transplantation of pancreatic islets for patients with difficult-to-control diabetes mellitus is severely hampered by the requirement for continuous immunosuppression and its associated morbidity. We report that allogeneic transplantation of genetically engineered (B2M-/-, CIITA-/-, CD47+), primary, hypoimmune, pseudo-islets (p-islets) results in their engraftment into a fully immunocompetent, diabetic non-human primate wherein they provide stable endocrine function and enable insulin independence without inducing any detectable immune response in the absence of immunosuppression. Hypoimmune primary p-islets may provide a curative cell therapy for type 1 diabetes mellitus.

Xenotransplantation literature update March 2023-November 2023

We present an updated report highlighting significant developments in the field of xenotransplantation since March 2023. The past six months have witnessed significant strides in the field and the emergence of novel research that is expected to facilitate the journey towards clinical trials. We are reviewing here the most pertinent findings from March 2023 to November 2023.