CDP7657, an anti-CD40L antibody lacking an Fc domain, inhibits CD40L-dependent immune responses without thrombotic complications: an in vivo study

Abstract

IntroductionCD40 ligand (CD40L) blockade has demonstrated efficacy in experimental autoimmune models. However, clinical trials of hu5c8, an anti-human CD40L IgG1 antibody, in systemic lupus erythematosus (SLE) were halted due to an increased incidence of thrombotic events. This study evaluated CDP7657, a high affinity PEGylated monovalent Fab' anti-CD40L antibody fragment, to assess whether an Fc-deficient molecule retains efficacy while avoiding the increased risk of thrombotic events observed with hu5c8.MethodsThe potency and cross-reactivity of CDP7657 was assessed in in vitro assays employing human and non-human primate leukocytes, and the capacity of different antibody formats to activate platelets in vitro was assessed using aggregometry and dense granule release assays. Given the important role CD40L plays in regulating humoral immunity, in vivo efficacy was assessed by investigating the capacity of Cynomolgus monkeys to generate immune responses to the tetanus toxoid antigen while the potential to induce thrombotic events in vivo was evaluated after repeat dosing of antibodies to Rhesus monkeys. A PEGylated anti-mouse CD40L was generated to assess efficacy in the New Zealand Black/White (NZB/W) mouse model of SLE.ResultsCDP7657 dose-dependently inhibited antigen-specific immune responses to tetanus toxoid in Cynomolgus monkeys, and in contrast to hu5c8, there was no evidence of pulmonary thrombovasculopathy in Rhesus monkeys. Aglycosyl hu5c8, which lacks Fc receptor binding function, also failed to induce thrombotic events in Rhesus monkeys. In vitro experiments confirmed that antibody constructs lacking an Fc, including CDP7657, did not induce human or monkey platelet activation. A PEGylated monovalent Fab' anti-mouse CD40L antibody also inhibited disease activity in the NZB/W mouse model of SLE after administration using a therapeutic dosing regimen where mice received antibodies only after they had displayed severe proteinuria.ConclusionsThese findings demonstrate for the first time that anti-CD40L antibodies lacking a functional Fc region do not induce thrombotic events in Rhesus monkeys and fail to activate platelets in vitro but, nevertheless retain pharmacological activity and support the investigation of CDP7657 as a potential therapy for systemic lupus erythematosus and other autoimmune diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0757-4) contains supplementary material, which is available to authorized users.

Repeated administration of dapirolizumab pegol in a randomised phase I study is well tolerated and accompanied by improvements in several composite measures of systemic lupus erythematosus disease activity and changes in whole blood transcriptomic profiles

“…The Fc portion of the full-length antibody has a critical role in the mechanism leading to thromboembolic events 17 18. Since dapirolizumab pegol lacks the Fc portion, it would not be expected to be associated with increased thromboembolic risk, a hypothesis supported by the absence of thromboembolic events in the present study and a previous non-human primate study in Rhesus monkeys 19. Multiple doses of dapirolizumab pegol were well tolerated.…”

“…It is proposed that the observed treatment-related (TR) thromboembolic events occurred as a result of platelet activation and aggregation, due to the formation of anti-CD40L antibody and soluble CD40L immune complexes that tether to platelets via binding of sCD40L to surface-expressed CD40 and activate platelets through interactions of the Fc with Fc gamma receptor IIA on the platelet surface 17 18. Dapirolizumab pegol (CDP7657), an anti-CD40L Fab’ antibody fragment conjugated to polyethylene glycol (PEG),19 was designed to address the potential safety problems caused by the Fc moiety, while retaining favourable pharmacokinetics (PK). In vitro assays have demonstrated that dapirolizumab pegol is a potent antagonist of CD40L binding to CD40, and dose-dependent inhibition of antibody responses with dapirolizumab pegol have been demonstrated in both humanised severe combined immune deficient mice and cynomolgus macaques 19 20.…”

Therapeutic effects of anti-CD154 antibody in cynomolgus monkeys with advanced rheumatoid arthritis

“…Thus, the severe RA condition in the control group (RA8) might induce thickening of the intima layer in pulmonary arteries. In contrast to human and nonhuman primate platelets, mouse platelets do not express FcRs 34 . Furthermore, the amount of blood that can be sampled is not sufficient to examine blood parameters serially due to the small body size of mice.…”

CD32a antibodies induce thrombocytopenia and type II hypersensitivity reactions in FCGR2A mice

“…28 CD32a likely mediated such thrombosis. 29 Hypothermia resulting from injection of a CD32a-activating mAb in FCGR2A mice was first reported by Taylor and colleagues in 2000. 25 In 2005, a report by van Royen-Kerkhof et al showed that MDE-8 prevented hemolytic anemia in CD32a-Tg mice lacking functional CD16, CD64, and FcgRIV, but did not address the possibility of anaphylaxis had such FcgRs been present.…”