A Monovalent Anti-Human CD28 Domain Antibody Antagonist: Preclinical Efficacy and Safety

Abstract

Targeting the CD28-CD80/86 pathway with an anti-CD28 antagonist is a promising alternative to current therapies for autoimmunity. However, attempts at generating conventional anti-CD28 mAbs lacking stimulatory activity has been challenging. In this study, we describe anti-human CD28 receptor antagonist domain Abs (dAbs) that are specific for human CD28. These dAbs are potent inhibitors of T cell activation, with an EC50 of 35 ± 14 ng/ml for inhibition of proliferation. The EC50 of 53 ± 11 ng/ml in an ex vivo CD28 receptor occupancy assay corresponds with in vitro functional activity, suggesting a direct correlation. The anti-CD28 dAb is equipotent in the inhibition of CD80- and CD86-mediated T cell proliferation and does not interfere with CTLA-4–mediated downmodulation of CD86 expression on APCs. The anti-CD28 dAbs are monomeric and do not demonstrate any evidence of agonism or costimulatory activity. In cynomolgus monkeys, the anti-CD28 dAb demonstrated pharmacodynamic activity, as measured by the inhibition of a T cell–dependent Ab response, without evidence of T cell depletion or cytokine release. Furthermore, there was a strong correlation between systemic exposure, duration, and extent of CD28 receptor occupancy, and pharmacodynamic activity. Taken together, these data support clinical evaluation of this novel anti-CD28 dAb for the treatment of autoimmune diseases.

Advantages ofPapio anubisfor preclinical testing of immunotoxicity of candidate therapeutic antagonist antibodies targeting CD28

“…20 Whereas it is now obvious that cynomolgus or rhesus macaques cannot constitute relevant species for preclinical immunotoxicity evaluation of emerging drugs targeting CD28, these animals still continue to be used for that purpose. 36 In this study, we found that the majority of baboon CD4 + memory T cells expressed CD28, similar to humans. Furthermore, we observed in vitro and trans vivo that baboon PBMC were activated, proliferated and secreted pro-inflammatory cytokines in response to agonist or superagonist anti-CD28 mAb stimulation.…”

Engineering of a Novel Anti-CD40L Domain Antibody for Treatment of Autoimmune Diseases

“…dAbs are bioactive as monomers and, owing to their small size and inherent stability, can be formatted into larger molecules to create drugs with prolonged serum half-lives or other pharmacological activities. dAbs have demonstrated preclinical efficacy; currently, they are being evaluated in the clinic (22,23).…”

Integrated Pharmacokinetic/Pharmacodynamic Analysis for Determining the Minimal Anticipated Biological Effect Level of a Novel Anti-CD28 Receptor Antagonist BMS-931699

“…In addition, anti-hCD28 dAb-001, a molecule that differs from BMS-931699 by two additional amino acids (ST) at the N terminus, was also studied in the preclinical setting. The additional amino acids in anti-hCD28 dAb-001 did not significantly affect the behavior of the dAb as tested across multiple biochemical and in vitro cellular assays (Suchard et al, 2013).…”

“…To this end, a novel Vk light chain domain antibody (dAb), the smallest functional binding unit corresponding to the variable regions of either the heavy or the light chains of a human antibody, was developed to monovalently bind to and antagonize the human CD28 (hCD28) receptor. BMS-931699 (lulizumab pegol, molecular weight 5 12 kDa) was formatted with 40-kDa branched polyethylene glycol to extend its half-life in vivo and was a potent inhibitor of hCD28-mediated T-cell proliferation, with an EC 50 of 2.9 nM in a human dendritic celldriven mixed lymphocyte reaction (MLR) assay (Suchard et al, 2013). In addition, anti-hCD28 dAb-001, a molecule that differs from BMS-931699 by two additional amino acids (ST) at the N terminus, was also studied in the preclinical setting.…”