Generation of Anti-complement “Prodrugs”

Abstract

Expression of biologically active molecules as fusion proteins with antibody Fc can substantially extend the plasma half-life of the active agent but may also influence function. We have previously generated a number of fusion proteins comprising a complement regulator coupled to Fc and shown that the hybrid molecule has a long plasma half-life and retains biological activity. However, several of the fusion proteins generated had substantially reduced biological activity when compared with the native regulator or regulator released from the Fc following papain cleavage. We have taken advantage of this finding to engineer a prodrug with low complement regulatory activity that is cleaved at sites of inflammation to release active regulator. Two model prodrugs, comprising, respectively, the four short consensus repeats of human decay accelerating factor (CD55) linked to IgG 4 Fc and the three NH 2 -terminal short consensus repeats of human decay accelerating factor linked to IgG 2 Fc have been developed. In each, specific cleavage sites for matrix metalloproteinases and/or aggrecanases have been incorporated between the complement regulator and the Fc. These prodrugs have markedly decreased complement inhibitory activity when compared with the parent regulator in vitro. Exposure of the prodrugs to the relevant enzymes, either purified, or in supernatants of cytokine-stimulated chondrocytes or in synovial fluid, efficiently cleaved the prodrug, releasing active regulator. Such agents, having negligible systemic effects but active at sites of inflammation, represent a paradigm for the next generation of anti-C therapeutics.

Longitudinally extensive NMO spinal cord pathology produced by passive transfer of NMO-IgG in mice lacking complement inhibitor CD59

“…2c). Increased susceptibility was also seen following treatment of CD59 +/+ astrocyte cultures with a CD59 neutralizing antibody [34], or with PI-PLC, which cleaves all membrane-bound GPI proteins including CD59 and CD55 (Fig. 2d) [35, 36].…”

Implication of Complement System and its Regulators in Alzheimers Disease

“…In addition, if they are targeted to the alternative, classical or MBL activation pathways, their long-term use can be detrimental, triggering immune complex disease and permitting bacterial infections as the key role of complement in innate immunity is prevented. Recently we have designed a strategy that renders the active component inactive as a prodrug, which activates at sites of inflammation [20]. Similar approach could be used for activation of prodrugs at sites of chronic inflammation including the CNS in AD.…”

A Review of Current Knowledge of the Complement System and the Therapeutic Opportunities in Inflammatory Arthritis

“…These agents can be modified to generate chimeric proteins with two different CRegs in a single CReg-Ig [167]. Modifications to the design of CReg-Ig have possibilities to create a prodrug-based delivery system that minimizes systemic effects of agent by releasing active agent only at the target site [168]. Membrane-targeted forms of CReg show promise, for example, targeted CD59 (sCD59-APT542) bound to the specific target and showed good results [133].…”