Zigakibart Potently Inhibits A Proliferation-Inducing Ligand-Mediated IgA Production, Addressing IgAN Pathogenesis...

Zigakibart is a humanized IgG4 monoclonal antibody (mAb) binding A proliferation-inducing ligand (APRIL, TNFSF13), a critical factor in IgA nephropathy (IgAN) pathogenesis. Results from the ongoing phase 1/2 ADU-CL-19 study (NCT03945318) have shown clinically meaningful outcomes in patients with IgAN treated with zigakibart.

We conducted a preclinical characterization of zigakibart using in vitro methods, including investigation of its binding to APRIL from various species, blocking of APRIL binding to transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B-cell maturation antigen (BCMA), investigation of the potency of zigakibart on BCMA- and TACI-reporter cells, and the assessment of the effect of APRIL blockade on human plasma cell survival and Ig production. In vivo methods were used to characterize zigakibart in human APRIL transgenic mice (hAPRIL-tg) and nonhuman primates.

Zigakibart potently blocked APRIL binding to TACI and BCMA and inhibited human plasma cell survival, which are key mediators in IgAN pathogenesis. Zigakibart selectively reduced circulating IgA and IgM to a greater extent than IgG and inhibited T-cell-independent antibody responses and IgA deposition in the kidney in vivo. Importantly, zigakibart inhibited IgA+ and IgM+ to a greater extent than IgG+ human plasma cells in vitro.

In these preclinical studies, zigakibart demonstrated robust pharmacological activity and, by neutralizing APRIL, inhibited markers associated with the pathogenesis of IgAN. Zigakibart therefore provides a potentially disease-modifying approach for IgAN treatment. Evaluation of the effects of zigakibart on proteinuria and long-term kidney function in adults with IgAN is ongoing in the ADU-CL-19 study and the phase 3 BEYOND study (NCT05852938).