Role of Anti-Fractalkine Antibody in Suppression of Joint Destruction by Inhibiting Migration of Osteoclast Precursors to the Synovium in Experimental Arthritis.

OBJECTIVE: To elucidate the role of the fractalkine (FKN)/CX3 CR1 pathway in joint destruction in rheumatoid arthritis. METHODS: We examined the effect of treatment with anti-mouse FKN (anti-mFKN) monoclonal antibody (mAb) on joint destruction and the migration of osteoclast precursors (OCPs) into the joint, using the collagen-induced arthritis (CIA) model. DBA/1 mice were immunized with bovine type II collagen to induce arthritis, and then treated with anti-mFKN mAb. Disease severity was monitored by arthritis score, and joint destruction was evaluated by soft x-ray and histologic analyses. Plasma levels of joint destruction markers were assessed by enzyme-linked immunosorbent assay. FKN expression on endothelial cells was detected by immunohistochemistry. Bone marrow-derived OCPs were labeled with fluorescein and transferred to mice with CIA, and the migration of the OCPs to the joints was then analyzed. RESULTS: Both prophylactic and therapeutic treatment with anti-mFKN mAb significantly decreased the arthritis and soft x-ray scores. Plasma levels of cartilage oligomeric matrix protein and matrix metalloproteinase 3 decreased after treatment with anti-mFKN mAb. Histologic analysis revealed that anti-mFKN mAb inhibited synovitis, pannus formation, and cartilage destruction, as well as suppressed bone damage, with a marked reduction in the number of tartrate-resistant acid phosphatase-positive osteoclasts. Anti-mFKN mAb strongly inhibited the migration of bone marrow-derived OCPs into the affected synovium. CONCLUSION: Anti-mFKN mAb notably ameliorates arthritis and joint destruction in the CIA model, as well as inhibits migration of OCPs into the synovium. These results suggest that inhibition of the FKN/CX3 CR1 pathway could be a novel strategy for treatment of both synovitis and joint destruction in rheumatoid arthritis.

Safety, tolerability, and pharmacodynamics of an anti-interleukin-1α/ß dual variable domain immunoglobulin in patients with osteoarthritis of the knee: a randomized phase 1 study.

OBJECTIVE: To investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ABT-981, a human dual variable domain immunoglobulin simultaneously targeting interleukin (IL)-1α and IL-1ß, in patients with knee osteoarthritis (OA). METHOD: This was a randomized, double-blind, placebo-controlled, single-center study of multiple subcutaneous (SC) injections of ABT-981 in patients with mild-to-moderate OA of the knee (NCT01668511). Three cohorts received ABT-981 (0.3, 1, or 3 mg/kg) or placebo every other week for a total of four SC injections, and one cohort received ABT-981 (3 mg/kg) or placebo every 4 weeks for a total of three SC injections. Assessment of safety and tolerability were the primary objectives. A panel of serum and urine biomarkers of inflammation and joint degradation were evaluated. RESULTS: A total of 36 patients were randomized (ABT-981, n = 28; placebo, n = 8); 31 (86%) completed the study. Adverse event (AE) rates were comparable between ABT-981 and placebo (54% vs 63%). The most common AE reported with ABT-981 vs placebo was injection site erythema (14% vs 0%). ABT-981 significantly reduced absolute neutrophil count and serum concentrations of IL-1α/IL-1ß, high-sensitivity C-reactive protein, and matrix metalloproteinase (MMP)-derived type 1 collagen. Serum concentrations of MMP-derived type 3 collagen and MMP-degraded C-reactive protein demonstrated decreasing trends with ABT-981. Antidrug antibodies were found in 37% of patients but were not associated with the incidence or severity of AEs. CONCLUSION: ABT-981 was generally well tolerated in patients with knee OA and engaged relevant tissue targets, eliciting an anti-inflammatory response. Consequently, ABT-981 may provide clinical benefit to patients with inflammation-driven OA.

Can tocilizumab decrease cartilage oligomeric matrix protein levels and disease activity in patients with long-standing rheumatoid arthritis?

Serum cartilage oligomeric matrix protein (COMP) level is a new marker of joint destruction in patients with rheumatoid arthritis (RA), and a new means of identifying patients with progressive joint damage. To evaluate the effect of tocilizumab (TCZ) on serum COMP levels, and whether there is any difference in this effect between patients failing on anti-TNF treatment and those failing on disease-modifying anti-rheumatic drugs (DMARDs). Fifty-one patients with long-standing RA (42 F, 9 M; mean age 62 ± 14 years; disease duration 4.5 ± 1.2 years) unresponsive to DMARDs and anti-TNF drugs were treated with TCZ 8 mg/kg/month. Serum COMP levels were measured by means of an ELISA at baseline and after six months of TCZ treatment; the patents' DAS28 scores and levels of RF (IgM, IgG, IgA), anti-CCP autoantibodies, ESR, CRP and IL-6 were evaluated at the same times. After six months of TCZ treatment, there was a significant decrease from baseline in ESR (46.1 [28.7-68.9] vs 34.3 [4.1- 58.8] mm/h, P <0.0001), CRP (2.2 [0.8-4.4] vs 1.3 [0.7-3.8] mg/dL, P <0.0001), TNF-α (21.3 [7.6-29.8] vs 17.4 [3.4-28.6] pg/mL, P=0.0408), IL-6 (6.9 [3.5-9.6] vs 3.4 [3.0-9.6] pg/mL, p<0.0001); anti-CCP (55.1 [30.2-273.0] vs 54.7 [30.1- 269.8] IU/mL, P=0.9683), RF-IgM (142.0 [48.0-260.0] vs 138.0 [42.0-243.0] IU/mL, P=0.4828), RF-IgA (81.0 [20-140] vs 108.0 [20-175] U/mL, P=0.0003), and RF-IgG (65.2 [30-158] vs 58.3 [38.0-158.0] U/mL, P=0.2671). There was also a significant decrease in DAS28 scores (4.3 [3.2-5.9] vs 3.7 [2.3-5.4], P <0.0001), and a non-significant decrease in serum COMP levels (0.95 [0.04-2.90] vs 0.98 [0.05-2.36] µg/mL; P = 0.9856). A decrease in serum COMP levels was observed in the patients failing on anti-TNF treatment or anti-DMARDs without any difference. TCZ therapy in patients with long-standing RA is associated with a significant decrease in ESR, CRP, IL-6, TNF and DAS28 values, and a decrease in serum COMP levels, particularly in patients failing on previous anti-TNF therapy. These findings suggest that TCZ has an effect on cartilage joint destruction after only six months of treatment.