The enhanced immunopharmacology of VIB4920, a novel Tn3 fusion protein and CD40L antagonist, and assessment of its safety profile in cynomolgus monkeys

CD40 ligand antagonist dazodalibep in Sjögren's disease: a randomized, double-blinded, placebo-controlled, phase 2 trial

Sjögren's disease (SjD) is a chronic, systemic autoimmune disease with no approved disease-modifying therapies. Dazodalibep (DAZ), a novel nonantibody fusion protein, is a CD40 ligand antagonist that blocks costimulatory signals between T and B cells and antigen-presenting cells, and therefore may suppress the wide spectrum of cellular and humoral responses that drive autoimmunity in SjD. This study was a phase 2, randomized, double-blinded, placebo (PBO)-controlled trial of DAZ with a crossover stage in two distinct populations of participants with SjD. Population 1 had moderate-to-severe systemic disease activity and population 2 had an unacceptable symptom burden and limited systemic organ involvement. All participants had a diagnosis of SjD, with 21.6% and 10.1% having an associated connective tissue disease (rheumatoid arthritis or systemic lupus erythematosus) in populations 1 and 2, respectively. The remaining participants would be considered as having primary Sjögren's syndrome. The primary endpoint for population 1 (n = 74) was the change from baseline in the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index at day 169. The primary endpoint for population 2 (n = 109) was the change from baseline in the European League Against Rheumatism Sjögren's Syndrome Patient Reported Index at day 169. The primary endpoints (least squares mean ± standard error) were achieved with statistical significance for both population 1 (DAZ, -6.3 ± 0.6; PBO, -4.1 ± 0.6; P = 0.0167) and population 2 (DAZ, -1.8 ± 0.2; PBO, -0.5 ± 0.2; P = 0.0002). DAZ was generally safe and well tolerated. Among the most frequently reported adverse events were COVID-19, diarrhea, headache, nasopharyngitis, upper respiratory tract infection, arthralgia, constipation and urinary tract infection. In summary, DAZ appears to be a potential new therapy for SjD and its efficacy implies an important role for the CD40/CD40 ligand pathway in its pathogenesis. ClinicalTrials.gov identifier: NCT04129164 .

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

Prior studies of anti-CD40 ligand (CD40L)-based immunosuppression demonstrated effective prevention of islet and kidney allograft rejection in nonhuman primate models; however, clinical development was halted because of thromboembolic complications. An anti-CD40L-specific monoclonal antibody, AT-1501 (Tegoprubart), was engineered to minimize risk of thromboembolic complications by reducing binding to Fcγ receptors expressed on platelets while preserving binding to CD40L. AT-1501 was tested in both a cynomolgus macaque model of intrahepatic islet allotransplantation and a rhesus macaque model of kidney allotransplantation. AT-1501 monotherapy led to long-term graft survival in both islet and kidney transplant models, confirming its immunosuppressive potential. Furthermore, AT-1501-based regimens after islet transplant resulted in higher C-peptide, greater appetite leading to weight gain, and reduced occurrence of cytomegalovirus reactivation compared with conventional immunosuppression. These data support AT-1501 as a safe and effective agent to promote both islet and kidney allograft survival and function in nonhuman primate models, warranting further testing in clinical trials.

The MIDORA trial: a phase II, randomised, double-blind, placebo-controlled, mechanistic insight and dosage optimisation study of the efficacy and safety of dazodalibep in patients with rheumatoid arthritis

OBJECTIVES

To evaluate the safety, efficacy and response duration of four different dosing regimens of dazodalibep (DAZ), a non-antibody biological antagonist of CD40L, in patients with rheumatoid arthritis (RA).

METHODS

This double-blind study included adult patients with moderate-to-severe active RA with a positive test for serum rheumatoid factor and/or anticitrullinated protein antibodies, an inadequate response to methotrexate, other conventional disease-modifying antirheumatic drugs or tumour necrosis factor-α inhibitors, and no prior treatment with B-cell depleting agents. Eligible participants were randomised equally to five groups receiving intravenous infusions of DAZ or placebo. The primary endpoint was the change from baseline in the Disease Activity Score-28 with C reactive protein (DAS28-CRP) at day 113. Participants were followed through day 309.

RESULTS

The study randomised 78 eligible participants. The change from baseline in DAS28-CRP (least squares means±SE) at day 113 was significantly greater for all DAZ groups (-1.83±0.28 to -1.90±0.27; p<0.05) relative to PBO (-1.06±0.26); significant reductions in DAS28-CRP were also observed for all DAZ groups at day 309. The distribution of adverse events was generally balanced among DAZ and PBO groups (74% and 63%, respectively). There were four serious adverse events deemed by investigators to be unrelated to study medication.

CONCLUSIONS

DAZ treatment for all dosage regimens significantly reduced DAS28-CRP at day 113 relative to PBO. The safety data suggest an acceptable safety and tolerability profile. Treatment effects at day 113 and the prolonged duration of responses after DAZ cessation support the use of longer dosing intervals.

TRIAL REGISTRATION NUMBER

NCT04163991.

What Therapeutic Regimen Will Be Optimal for Initial Clinical Trials of Pig Organ Transplantation?

We discuss what therapeutic regimen might be acceptable/successful in the first clinical trial of genetically engineered pig kidney or heart transplantation. As regimens based on a calcineurin inhibitor or CTLA4-Ig have proved unsuccessful, the regimen we administer to baboons is based on induction therapy with antithymocyte globulin, an anti-CD20 mAb (Rituximab), and cobra venom factor, with maintenance therapy based on blockade of the CD40/CD154 costimulation pathway (with an anti-CD40 mAb), with rapamycin, and a corticosteroid. An anti-inflammatory agent (etanercept) is administered for the first 2 wk, and adjuvant therapy includes prophylaxis against thrombotic complications, anemia, cytomegalovirus, and pneumocystis. Using this regimen, although antibody-mediated rejection certainly can occur, we have documented no definite evidence of an adaptive immune response to the pig xenograft. This regimen could also form the basis for the first clinical trial, except that cobra venom factor will be replaced by a clinically approved agent, for example, a C1-esterase inhibitor. However, none of the agents that block the CD40/CD154 pathway are yet approved for clinical use, and so this hurdle remains to be overcome. The role of anti-inflammatory agents remains unproven. The major difference between this suggested regimen and those used in allotransplantation is the replacement of a calcineurin inhibitor with a costimulation blockade agent, but this does not appear to increase the complications of the regimen.

Follicular helper T cells: potential therapeutic targets in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease with joint and systemic inflammation that is accompanied by the production of autoantibodies, such as rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies. Follicular helper T (Tfh) cells, which are a subset of CD4+ T cells, facilitate germinal center (GC) reactions by providing signals required for high-affinity antibody production and the generation of long-lived antibody-secreting plasma cells. Uncontrolled expansion of Tfh cells is observed in various systemic autoimmune diseases. Particularly, the frequencies of circulating Tfh-like (cTfh-like) cells, their subtypes and synovial-infiltrated T helper cells correlate with disease activity in RA patients. Therefore, reducing autoantibody production and restricting excessive Tfh cell responses are ideal ways to control RA pathogenesis. The present review summarizes current knowledge of the involvement of Tfh cells in RA pathogenesis and highlights the potential of these cells as therapeutic targets.

[The CD40-CD40L axis: Current and future implications in clinical immunology]

The CD40-CD40 ligand (CD40L) pathway is a backbone of communication between cells of the immune system. It makes it possible to generate a proinflammatory signal and thus participates in the pathogenesis of dysimmune diseases, transplant rejection and atherosclerosis. Because of this therapeutic target of choice, several generations of anti-CD40L monoclonal antibodies have emerged since the 1990s. The first generation of antibodies was responsible for thromboembolic toxicity for which the mechanisms are starting to be defined. New generations of antibodies were designed to overcome this toxicity and are still being developed in lupus, rheumatoid arthritis, Sjogren's syndrome or immunologic thrombocytopenia. In addition to these targeted therapies, there are data suggesting the impact of several drugs among molecules used in cardiology and clinical immunology on the level of CD40L. The objective of this review is to recall the clinical issues related to the CD40-CD40L axis and to present current or future treatments that block CD40L which would allow clinicians to diversify their options for managing dysimmune diseases.

Molecular basis and therapeutic implications of CD40/CD40L immune checkpoint

The CD40 receptor and its ligand CD40L is one of the most critical molecular pairs of the stimulatory immune checkpoints. Both CD40 and CD40L have a membrane form and a soluble form generated by proteolytic cleavage or alternative splicing. CD40 and CD40L are widely expressed in various types of cells, among which B cells and myeloid cells constitutively express high levels of CD40, and T cells and platelets express high levels of CD40L upon activation. CD40L self-assembles into functional trimers which induce CD40 trimerization and downstream signaling. The canonical CD40/CD40L signaling is mediated by recruitment of TRAFs and NF-κB activation, which is supplemented by signal pathways such as PI3K/AKT, MAPKs and JAK3/STATs. CD40/CD40L immune checkpoint leads to activation of both innate and adaptive immune cells via two-way signaling. CD40/CD40L interaction also participates in regulating thrombosis, tissue inflammation, hematopoiesis and tumor cell fate. Because of its essential role in immune activation, CD40/CD40L interaction has been regarded as an attractive immunotherapy target. In recent years, significant advance has been made in CD40/CD40L-targeted therapy. Various types of agents, including agonistic/antagonistic monoclonal antibodies, cellular vaccines, adenoviral vectors and protein antagonist, have been developed and evaluated in early-stage clinical trials for treating malignancies, autoimmune diseases and allograft rejection. In general, these agents have demonstrated favorable safety and some of them show promising clinical efficacy. The mechanisms of benefits include immune cell activation and tumor cell lysis/apoptosis in malignancies, or immune cell inactivation in autoimmune diseases and allograft rejection. This review provides a comprehensive overview of the structure, processing, cellular expression pattern, signaling and effector function of CD40/CD40L checkpoint molecules. In addition, we summarize the progress, targeted diseases and outcomes of current ongoing and completed clinical trials of CD40/CD40L-targeted therapy.

Advances in selecting appropriate non-rodent species for regulatory toxicology research: Policy, ethical, and experimental considerations

In vivo animal studies are required by regulatory agencies to investigate drug safety before clinical trials. In this review, we summarize the process of selecting a relevant non-rodent species for preclinical studies. The dog is the primary, default non-rodent used in toxicology studies with multiple scientific advantages, including adequate background data and availability. Rabbit has many regulatory advantages as the first non-rodent for the evaluation of reproductive and developmental as well as local toxicity. Recently, minipigs have increasingly replaced dogs and rabbits in toxicology studies due to ethical and scientific advantages including similarity to humans and breeding habits. When these species are not relevant, nonhuman primates (NHPs) can be used as the available animal models, especially in toxicology studies investigating biotherapeutics. Particularly, based on the phylogenetic relationships, the use of New-World marmosets can be considered before Old-World monkeys, especially cynomolgus with robust historical data. Importantly, the use of NHPs should be justified in terms of scientific benefits considering target affinity, expression pattern, and pharmacological cross-reactivity. Strict standards are required for the use of animals. Therefore, this review is helpful for the selection of appropriate non-rodent in regulatory toxicology studies by providing sufficient regulatory, ethical, and scientific data for each species.

Development and Differentiation in Monobodies Based on the Fibronectin Type 3 Domain

As a non-antibody scaffold, monobodies based on the fibronectin type III (FN3) domain overcome antibody size and complexity while maintaining analogous binding loops. However, antibodies and their derivatives remain the gold standard for the design of new therapeutics. In response, clinical-stage therapeutic proteins based on the FN3 domain are beginning to use native fibronectin function as a point of differentiation. The small and simple structure of monomeric monobodies confers increased tissue distribution and reduced half-life, whilst the absence of disulphide bonds improves stability in cytosolic environments. Where multi-specificity is challenging with an antibody format that is prone to mis-pairing between chains, multiple FN3 domains in the fibronectin assembly already interact with a large number of molecules. As such, multiple monobodies engineered for interaction with therapeutic targets are being combined in a similar beads-on-a-string assembly which improves both efficacy and pharmacokinetics. Furthermore, full length fibronectin is able to fold into multiple conformations as part of its natural function and a greater understanding of how mechanical forces allow for the transition between states will lead to advanced applications that truly differentiate the FN3 domain as a therapeutic scaffold.

The enhanced immunopharmacology of VIB4920, a novel Tn3 fusion protein and CD40L antagonist, and assessment of its safety profile in cynomolgus monkeys

BACKGROUND AND PURPOSE

Inhibition of the T- and B-cell interaction through the CD40/CD40 ligand (L) axis is a favourable approach for inflammatory disease treatment. Clinical studies of anti-CD40L molecules in autoimmune diseases have met challenges because of thromboembolic events and adverse haemostasis. VIB4920 (formerly MEDI4920) is a novel CD40L antagonist and Tn3 fusion protein designed to prevent adverse haemostasis and immunopharmacology. We evaluated the pharmacokinetics, activity and toxicity of VIB4920 in monkeys.

EXPERIMENTAL APPROACH

Cynomolgus monkeys received i.v. or s.c. 5-300 mg·kg^-1 VIB4920 or vehicle, once weekly for 1 month (Studies 1 and 2) or 28 weeks (Study 3). VIB4920 exposure and bioavailability were determined using pharmacokinetic analyses, and immune cell population changes via flow cytometry. Pharmacological activity was evaluated by measuring the animals' capacity to elicit an immune response to keyhole limpet haemocyanin (KLH) and tetanus toxoid (TT).

KEY RESULTS

VIB4920 demonstrated linear pharmacokinetics at multiple doses. Lymphocyte, monocyte, cytotoxic T-cell and NK cell counts were not significantly different between treatment groups. B-cell counts reduced dose-dependently and the T-cell dependent antibody response to KLH was suppressed by VIB4920 dose-dependently. The recall response to TT was similar across treatment groups. No thromboembolic events or symptoms of immune system dysfunctionality were observed.

CONCLUSIONS AND IMPLICATIONS

VIB4920 demonstrated an acceptable safety profile in monkeys. VIB4920 showed favourable pharmacokinetics, dose-dependent inhibition of a neoantigen-specific immune response and no adverse effects on immune function following long-term use. Our data support the use of VIB4920 in clinical trials.