Rheumatoid Arthritis: Sasso EH

Tracey D, Klareskog L, Sasso EH, Salfeld JG, Tak PP. · Abbott Bioresearch Center, Worcester, MA, USA. · Pharmacol Ther. · Pubmed #18155297 No free full text.

Abstract: During the past 30 years, elucidation of the pathogenesis of rheumatoid arthritis, Crohn's disease, psoriasis, psoriatic arthritis and ankylosing spondylitis at the cellular and molecular levels has revealed that these diseases share common mechanisms and are more closely related than was previously recognized. Research on the complex biology of tumor necrosis factor (TNF) has uncovered many mechanisms and pathways by which TNF may be involved in the pathogenesis of these diseases. There are 3 TNF antagonists currently available: adalimumab, a fully human monoclonal antibody; etanercept, a soluble receptor construct; and infliximab, a chimeric monoclonal antibody. Two other TNF antagonists, certolizumab and golimumab, are in clinical development.The remarkable efficacy of TNF antagonists in these diseases places TNF in the center of our understanding of the pathogenesis of many immune-mediated inflammatory diseases. The purpose of this review is to discuss the biology of TNF and related family members in the context of the potential mechanisms of action of TNF antagonists in a variety of immune-mediated inflammatory diseases. Possible mechanistic differences between TNF antagonists are addressed with regard to their efficacy and safety profiles.

Sasso EH, Merrill C, Furst TE. · Department of Medicine, University of Washington, Seattle, USA. · Ther Apher. · Pubmed #11354304 No free full text.

Abstract: Studies of the humoral effects of the Prosorba column were conducted in conjunction with the Phase 3 trial of Prosorba versus sham therapy for rheumatoid arthritis (RA). When perfused with normal human plasma in vitro, Prosorba bound predominantly IgG with a maximal capacity of approximately 462 g of Ig per Prosorba column, equal to about 1.5% of circulating IgG. Prosorba treatment did not alter the concentrations of albumin, IgG, IgM, and IgA in 3 RA patients, except for a small dilutional effect. Kinetic studies demonstrated that Prosorba removed IgG > IgM, IgA, and IgM rheumatoid factor (RF) during the initial moments of apheresis and almost exclusively IgM RF after 15 min. No net protein removal occurred at > or = 60 min. Mean values of circulating immune complexes (CICs) were not significantly decreased by 12 weekly treatments. Complement was activated by the apheresis system upstream of the Prosorba column without changing C3 or C4 levels. We conclude that the Prosorba mechanism of action in RA is not bulk removal of Ig, but might involve modification of the CIC repertoire and could include, but not be limited to, effects related to complement activation.

Emery P, Genovese MC, van Vollenhoven R, Sharp JT, Patra K, Sasso EH. · Leeds Teaching Hospital, Rheumatology, Leeds, United Kingdom. · J Rheumatol. · Pubmed #19369462 No free full text.

Abstract: OBJECTIVE: To determine the relationship between radiographic progression and clinical response for adalimumab plus methotrexate (MTX) versus either monotherapy in patients with early rheumatoid arthritis (RA) in the PREMIER study. METHODS: Patients with early RA who received adalimumab plus MTX (n = 240), adalimumab (n = 222), or MTX (n = 216) were grouped by American College of Rheumatology (ACR) response, 28-joint Disease Activity Score (DAS28), or remission-like state [tender joint count (TJC) = 0; DAS28 < 2.6; swollen joint count = 0; ACR100] at 26 and 104 weeks. Radiographic progression was assessed by cumulative probability plots, mean changes in total Sharp score (DeltaTSS), and percentages of progressors (DeltaTSS > 0.5). RESULTS: Across the spectrum of clinical outcomes, including ACR20 nonresponses and remission-like responses, therapy with adalimumab plus MTX permitted less radiographic progression at Weeks 26 and 104 than MTX monotherapy. Adalimumab monotherapy was generally intermediate. A strong, proportional relationship was observed between clinical response and radiographic efficacy only for MTX monotherapy. The monotherapies approximated the radiographic efficacy of adalimumab plus MTX only among remission-like responders, although progression was significantly greater with MTX monotherapy versus adalimumab plus MTX for patients with TJC = 0. Concurrent clinical (DAS28 < 2.6) and radiographic (DeltaTSS <or= 0.5) remission was significantly more frequent at Week 104 with adalimumab plus MTX (45%) than with adalimumab (25%) or MTX (18%) monotherapy. CONCLUSION: In patients with early RA, adalimumab plus MTX resulted in less radiographic progression than MTX monotherapy across the spectrum of clinical response, including ACR20 non-responses and remission-like responses.

Kaymakcalan Z, Sakorafas P, Bose S, Scesney S, Xiong L, Hanzatian DK, Salfeld J, Sasso EH. · Department of Biologics, Abbott Bioresearch Center, Worcester, MA 01605, USA. · Clin Immunol. · Pubmed #19188093 No free full text.

Abstract: The TNF antagonists adalimumab, infliximab, and etanercept are effective treatments for rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis, but only adalimumab and infliximab have been found to be efficacious in Crohn's disease. The present studies evaluated the TNF-binding and complement-activating properties of adalimumab, infliximab, and etanercept to determine whether these properties may explain differences in their clinical efficacy profiles. Association and dissociation rates of binding to soluble TNF were measured by surface plasmon resonance, and were found to be similar for adalimumab, infliximab, and etanercept, as were their calculated binding affinities. Avidity of binding to soluble TNF, measured by KinExA technology, was 10- to 20-fold greater for soluble etanercept (K(D)=0.4 picomolars [pM]) than for soluble adalimumab or infliximab (K(D)=8.6 and 4.2 pM, respectively). (125)I-adalimumab, -infliximab, and -etanercept bound to membrane TNF (mTNF) on mTNF-transfected cells with similar affinities (K(D)=483, 468, and 445 pM, respectively) that were each lower than for soluble TNF. Complement-dependent cytotoxicity (CDC) was induced in mTNF-transfected cells by adalimumab and infliximab, but was not induced in activated normal human PBMC by any of the 3 agents. In conclusion, the binding properties of adalimumab, infliximab, and etanercept were similar for soluble TNF, and very similar for mTNF, yet none of the 3 was able to induce CDC in activated PBMC. These results suggest that the different clinical efficacy profiles of these agents are not explained by differences in either TNF-intrinsic binding properties or complement lysis.