Pain Relief in Nonhuman Primate Models of Arthritis.

Animal models of rheumatoid arthritis are important in the elucidation of etiopathogenic mechanisms of the disease and for the development of promising new therapies. Species specificity of new biological compounds and their mode of action preclude safety and efficacy testing in rodent models of disease. Nonhuman primates (NHP) can fill this niche and provide the only relevant model. Over the last two decades models of collagen-induced arthritis (CIA) were developed in the rhesus monkey and the common marmoset. However, NHP are higher-order animals and complex sentient beings. So especially in models where pain is an intricate part of the disease, analgesia needs to be addressed because of ethical considerations. In our model, a morphine-based pain relief was used that does not interfere with the normal development of disease allowing us to evaluate important mechanistic aspects of the arthritis.

Safety, Biodistribution, and Efficacy of an AAV-5 Vector Encoding Human Interferon-Beta (ART-I02) Delivered via Intra-Articular Injection in Rhesus Monkeys with Collagen-Induced Arthritis.

Preclinical studies to assess biodistribution, safety, and initial efficacy of ART-I02, an adeno-associated type 5 (rAAV5) vector expressing human interferon ß (hIFN-ß), were performed in a total of 24 rhesus monkeys with collagen-induced arthritis. All monkeys were naïve or showed limited neutralizing antibody (Nab) titers to AAV5 at the start of the study. Animals were injected with a single intra-articular dose of ART-I02 or placebo, consisting of 3.2×10(13) vg (Dose A=maximum feasible dose), 4.58×10(12) vg (Dose B), or placebo in the first affected finger joint, the ipsilateral knee, and ankle joint at the same time point. Animals were monitored for clinical parameters and well-being with a maximum of 4 weeks, with the option that the severity of arthritis could necessitate an earlier time point of sacrifice. No adverse events were noted after injection of ART-I02. No abnormalities were observed after histological evaluation of all organs. At both dose levels, immunohistochemical staining indicated expression of hIFN-ß. In animals injected with Dose A, we observed stabilization or a reduction in swelling in the finger joint in which vector was administered. The highest copy numbers of vector DNA were detected in synovial tissue of the injected joint and the draining lymph node of the injected knee. High titers of Nab to rAAV5 were observed at the end of the study. Five monkeys developed an rAAV5-specific T-cell response. Two monkeys developed Nab to hIFN-ß. In conclusion, intra-articular injection of ART-I02 was well-tolerated and did not induce adverse events. After administration of Dose A of ART-I02, we observed a beneficial effect on joint swelling, substantiated by decreased histological inflammation and bone erosion scores. A GMP vector for clinical application has been manufactured and is currently being tested in GLP rodent studies, with the aim to move forward to a clinical trial.

The preclinical pharmacology of the high affinity anti-IL-6R Nanobody® ALX-0061 supports its clinical development in rheumatoid arthritis.

INTRODUCTION: The pleiotropic cytokine interleukin-6 (IL-6) plays an important role in the pathogenesis of different diseases, including rheumatoid arthritis (RA). ALX-0061 is a bispecific Nanobody® with a high affinity and potency for IL-6 receptor (IL-6R), combined with an extended half-life by targeting human serum albumin. We describe here the relevant aspects of its in vitro and in vivo pharmacology. METHODS: ALX-0061 is composed of an affinity-matured IL-6R-targeting domain fused to an albumin-binding domain representing a minimized two-domain structure. A panel of different in vitro assays was used to characterize the biological activities of ALX-0061. The pharmacological properties of ALX-0061 were examined in cynomolgus monkeys, using plasma levels of total soluble (s)IL-6R as pharmacodynamic marker. Therapeutic effect was evaluated in a human IL-6-induced acute phase response model in the same species, and in a collagen-induced arthritis (CIA) model in rhesus monkeys, using tocilizumab as positive control. RESULTS: ALX-0061 was designed to confer the desired pharmacological properties. A 200-fold increase of target affinity was obtained through affinity maturation of the parental domain. The high affinity for sIL-6R (0.19 pM) translated to a concentration-dependent and complete neutralization of sIL-6R in vitro. In cynomolgus monkeys, ALX-0061 showed a dose-dependent and complete inhibition of hIL-6-induced inflammatory parameters, including plasma levels of C-reactive protein (CRP), fibrinogen and platelets. An apparent plasma half-life of 6.6 days was observed after a single intravenous administration of 10 mg/kg ALX-0061 in cynomolgus monkeys, similar to the estimated expected half-life of serum albumin. ALX-0061 and tocilizumab demonstrated a marked decrease in serum CRP levels in a non-human primate CIA model. Clinical effect was confirmed in animals with active drug exposure throughout the study duration. CONCLUSIONS: ALX-0061 represents a minimized bispecific biotherapeutic of 26 kDa, nearly six times smaller than monoclonal antibodies. High in vitro affinity and potency was demonstrated. Albumin binding as a half-life extension technology resulted in describable and expected pharmacokinetics. Strong IL-6R engagement was shown to translate to in vivo effect in non-human primates, demonstrated via biomarker deregulation as well as clinical effect. Presented results on preclinical pharmacological properties of ALX-0061 are supportive of clinical development in RA.

PDL241, a novel humanized monoclonal antibody, reveals CD319 as a therapeutic target for rheumatoid arthritis.

INTRODUCTION: Targeting the CD20 antigen has been a successful therapeutic intervention in the treatment of rheumatoid arthritis (RA). However, in some patients with an inadequate response to anti-CD20 therapy, a persistence of CD20- plasmablasts is noted. The strong expression of CD319 on CD20- plasmablast and plasma cell populations in RA synovium led to the investigation of the potential of CD319 as a therapeutic target. METHODS: PDL241, a novel humanized IgG1 monoclonal antibody (mAb) to CD319, was generated and examined for its ability to inhibit immunoglobulin production from plasmablasts and plasma cells generated from peripheral blood mononuclear cells (PBMC) in the presence and absence of RA synovial fibroblasts (RA-SF). The in vivo activity of PDL241 was determined in a human PBMC transfer into NOD scid IL-2 gamma chain knockout (NSG) mouse model. Finally, the ability of PDL241 to ameliorate experimental arthritis was evaluated in a collagen-induced arthritis (CIA) model in rhesus monkeys. RESULTS: PDL241 bound to plasmablasts and plasma cells but not naïve B cells. Consistent with the binding profile, PDL241 inhibited the production of IgM from in vitro PBMC cultures by the depletion of CD319+ plasmablasts and plasma cells but not B cells. The activity of PDL241 was dependent on an intact Fc portion of the IgG1 and mediated predominantly by natural killer cells. Inhibition of IgM production was also observed in the human PBMC transfer to NSG mouse model. Treatment of rhesus monkeys in a CIA model with PDL241 led to a significant inhibition of anti-collagen IgG and IgM antibodies. A beneficial effect on joint related parameters, including bone remodeling, histopathology, and joint swelling was also observed. CONCLUSIONS: The activity of PDL241 in both in vitro and in vivo models highlights the potential of CD319 as a therapeutic target in RA.

New drug discovery strategies for rheumatoid arthritis: a niche for nonhuman primate models to address systemic complications in inflammatory arthritis.

INTRODUCTION: Despite the tremendous advances made in the treatment of rheumatoid arthritis (RA), there is still excess mortality observed in RA patients, which is mainly caused by cardiovascular disease (CVD). Altered lipid metabolism plays a major role in the etiology of CVD. A second common complication observed in RA patients is anemia. Both conditions are serious, reduce quality of life and are undertreated. AREAS COVERED: The authors postulate that there is a specific niche for nonhuman primate models of inflammatory arthritis to address these systemic complications that occur in RA. Furthermore, the authors postulate that these nonhuman primate models are a useful platform to unveil the mechanisms underlying dyslipidemia and anemia, which are responsible for the manifestation of these complications. EXPERT OPINION: The presence of currently untreated systemic complications of RA, such as dyslipidemia and anemia, provides interesting opportunities to include these in the preclinical evaluation of new therapies. In the selection of relevant models for the evaluation of new treatments for RA or the identification of new targets for therapy, we postulate that nonhuman primates should be considered as a valid preclinical model. Because of their closer immunological and physiological proximity to humans, these models in nonhuman primates can be valuable for studying disease-related aspects that cannot be addressed in rodent models.

Collagen-induced arthritis in common marmosets: a new nonhuman primate model for chronic arthritis.

INTRODUCTION: There is an ever-increasing need for animal models to evaluate efficacy and safety of new therapeutics in the field of rheumatoid arthritis (RA). Particularly for the early preclinical evaluation of human-specific biologicals targeting the progressive phase of the disease, there is a need for relevant animal models. In response to this requirement we set out to develop a model of collagen-induced arthritis (CIA) in a small-sized nonhuman primate species (300 to 400 g at adult age); that is, the common marmoset (Callithrix jacchus). METHODS: Twenty-two animals divided into three experiments were immunized with collagen type II (CII) of either bovine or chicken origin with different immunization strategies. The animals were analyzed for clinical manifestation of arthritis, hematology and clinical chemistry, immunological responses against CII and histopathological features of the arthritis. RESULTS: Clinically manifest arthritis was observed in almost 100% (21 out of 22) of the animals. Fifty percent of the animals developed semi-acute CIA while the other 50% displayed a more chronic disease. Both cellular (CD3/CD4 and CD3/CD8) and humoral responses (IgM and IgG) against CII were involved in the development of the disease. Besides mild histopathological changes in bone and cartilage, severe inflammation in extraarticular tissues like periosteum and subcutaneous tissues was observed. CONCLUSIONS: This new model in marmosets more closely resembles chronic RA with respect to the chronic disease course and pathomorphological presentation than the more acute monophasic and destructive CIA model in macaques. This model can therefore fill a niche in preclinical testing of new human specific therapeutics.

The significance of non-human primates as preclinical models of human arthritic disease.

BACKGROUND: The broad immunological gap between inbred SPF-raised strains of mice and rats and the diverse rheumatoid arthritis (RA) patient population limits the predictive value of the existing disease models for clinical success of new therapies, in particular for those using highly specific biologicals. OBJECTIVE: This review argues that because of their closer immunological and physiological proximity to patients, disease models in non-human primates (NHPs) may bridge this gap and help reduce the failure of many (± 80%) new therapies in clinical trials. In various research areas, NHPs are an accepted intermediate between disease models in rodents and the ultimate introduction for clinical use in patients. However, with the exception of transplantation, this is not the case for immune-mediated inflammatory disorders, such as RA, although useful preclinical models are being developed. METHOD: The validity and use of the rhesus monkey model of collagen-induced arthritis as a preclinical RA model is reviewed. The discussion comprises present genetic and immunological aspects, biomarkers, and an overview of published preclinical therapy evaluations. CONCLUSION: It is time to consider the use of NHPs with a greater evolutionary proximity to humans as models for preclinical evaluation of new human-specific drugs for arthritic disease.