title: Pharmacokinetics and immunoglobulin response of subcutaneous and intravenous atacicept in patients with systemic lupus erythematosus.
abstract: Atacicept, a recombinant fusion protein of the TACI receptor and human IgG, is an inhibitor of B-Lymphocyte Stimulator (BLyS) and APRIL, potent stimulators of B cell maturation, proliferation, and survival. Pharmacokinetics (PKs) and biological activity of intravenous (iv) and subcutaneous (sc) atacicept are described here for patients with systemic lupus erythematosus in two randomized, double-blind, placebo-controlled, Phase Ib studies. Study 1: Six cohorts of eight patients received sc atacicept (single dose: 0.3, 1, 3, or 9 mg/kg; four weekly doses: 1 or 3 mg/kg), or placebo (3:1 ratio). Study 2: Four cohorts of six patients received iv atacicept (single dose: 3, 9, or 18 mg/kg; multiple dose: 2 x 9 mg/kg), or matching placebo (5:1 ratio). PK profiles were determined through serum atacicept and atacicept-BLyS complex, and biological activity through IgA, IgG, and IgM levels. PK profiles of atacicept were influenced by saturable binding between atacicept and its ligands, and were consistent and predictable across doses and regimens. Atacicept's biological activity was compatible with its presumed mechanism of action. Bioavailability was approximately 30-40% following sc or iv administration and similar doses yielded similar biological activity irrespective of administration route. This observation may have a mechanistic foundation and may inform dosing regimen design for future studies.
authors.affiliation: ZymoGenetics, 1201 Eastlake Avenue East, Seattle, Washington 98102, USA.
authors.forename: I
authors.initials: I
authors.lastname: Nestorov
authors.forename: O
authors.initials: O
authors.lastname: Papasouliotis
authors.forename: C
authors.initials: C
authors.lastname: Pena Rossi
authors.forename: A
authors.initials: A
authors.lastname: Munafo
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000097:blood*; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000188:drug therapy* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007136:Immunoglobulins; D011993:Recombinant Fusion Proteins; C524618:TACI receptor-IgG Fc fragment fusion protein