823-P: Molecular and Pharmacological Properties of GZR4, a Once-Weekly Insulin Analog

Introduction: It was reported that the complex, formed between acylated insulin and human serum albumin (HSA), enters an essentially inactive albumin-bound depot, leading to a dramatically decreased potency.

Objectives: This study was performed to develop a more potent once-weekly insulin analog GZR4 and investigate its molecular and pharmacological properties.

Methods: In vitro assays were employed to characterize the biological attributes of GZR4 through its interactions with HSA and insulin receptor (IR), intracellular signaling, and cellular metabolic responses. In vivo efficacy was evaluated in T1DM STZ treated rats and db/db mice, with Icodec (once-weekly insulin under development) as positive control.

Results: GZR4 was designed by introducing C22 fatty acid to B29 lysine of insulin backbone (A14E, B16H, B25H, desB30 human insulin) through 12×OEG linker. GZR4 displayed 2-fold increase in HSA binding, while 1.5-fold decrease in IR-A binding, 2.5-fold decrease in IR-B binding compared with insulin Icodec. In the presence of HSA, a sandwich binding model showed GZR4 retained IR binding response with 10.2 RU while Icodec essentially displayed no binding, IR phosphorylation activity relative to human insulin was 0.233%±0.012% and 0.034%±0.002% for GZR4 and Icodec respectively. In adipocytes, GZR4 stimulated lipogenesis in a similar dose-dependent manner as human insulin. HbA1c-lowering capability of GZR4 was 3 times higher than that of Icodec in TIDM STZ treated rats and db/db mice.

Conclusions: Current studies demonstrate that the length of the OEG linker between insulin and fatty acid plays an essential role on the potency of the acylated insulins. In the presence of HSA, GZR4 retains partially in vitro bioactivity while Icodec entered an essentially inactive state. Accordingly, GZR4 showed higher in vivo hypoglycemia efficacy than Icodec. Pharmacological evaluation revealed that GZR4 has the potential to be a novel once-weekly basal insulin with lower dosing compared to Icodec.