Specificity of human anti-variable heavy (VH ) chain autoantibodies and impact on the design and clinical testing of a VH domain antibody antagonist of tumour necrosis factor-α receptor 1.

During clinical trials of a tumour necrosis factor (TNF)-R1 domain antibody (dAb™) antagonist (GSK1995057), infusion reactions consistent with cytokine release were observed in healthy subjects with high levels of a novel, pre-existing human anti-VH (HAVH) autoantibody. In the presence of HAVH autoantibodies, GSK1995057 induced cytokine release in vitro due to binding of HAVH autoantibodies to a framework region of the dAb. The epitope on GSK1995057 was characterized and dAbs with reduced binding to HAVH autoantibodies were generated; pharmacological comparability was determined in human in-vitro systems and in-vivo animal experiments. A Phase I clinical trial was conducted to investigate the safety and tolerability of the modified dAb (GSK2862277). A significant reduction in HAVH binding was achieved by adding a single alanine residue at the C-terminus to create GSK2862277. Screening a pool of healthy donors demonstrated a reduced frequency of pre-existing autoantibodies from 51% to 7%; in all other respects, GSK2862277 and the parent dAb were comparable. In the Phase I trial, GSK2862277 was well tolerated by both the inhaled and intravenous routes. One subject experienced a mild infusion reaction with cytokine release following intravenous dosing. Subsequently, this subject was found to have high levels of a novel pre-existing antibody specific to the extended C-terminus of GSK2862277. Despite the reduced binding of GSK2862277 to pre-existing HAVH autoantibodies, adverse effects associated with the presence of a novel pre-existing antibody response specific to the modified dAb framework were identified and highlight the challenge of developing biological antagonists to this class of receptor.

Autoantibodies to variable heavy (VH) chain Ig sequences in humans impact the safety and clinical pharmacology of a VH domain antibody antagonist of TNF-α receptor 1.

PURPOSE: To investigate the impact of a new class of anti-Ig autoantibodies reactive with variable heavy (VH) chain framework sequences (human anti-VH autoantibodies) on the pharmacology and safety of an anti-TNFR1 VH domain antibody (GSK1995057) in healthy human subjects. METHODS: Single-blind, randomised, placebo-controlled dose escalation study in which healthy males (n = 28) received a single GSK1995057 intravenous infusion of 0.0004, 0.002 and 0.01 mg/kg. All enrolled subjects were pre-screened for human anti-VH (HAVH) autoantibody status and prospectively stratified accordingly. Serum samples from drug-naïve, HAVH-positive volunteers were used to investigate the effect of HAVH/GSK1995057 complexes on the activation of TNFR1 and cytokine release in vitro. RESULTS: Human anti-VH autoantibodies were detected in approximately 50 % of drug-naïve healthy human subjects and clinical and in vitro studies were performed to evaluate their impact on the pharmacology and safety of GSK1995057. We demonstrated that formation of HAVH autoantibody/GSK1995057 complexes activated TNFR1 and caused cytokine release in vitro in some, but not all, of the human cell types tested. When GSK1995057 was administered to healthy subjects, clinical and physiological signs of cytokine release were observed in two HAVH autoantibody-positive subjects following GSK1995057 infusion. In vitro, HAVH autoantibody levels correlated with TNFR1-dependent cytokine release and propensity for cytokine release in humans following GSK1995057 dosing. CONCLUSIONS: Our data support a greater focus on the impact of pre-existing, drug-reactive autoantibodies on the development of antibody fragments and biotherapeutics targeting cell surface receptors.