Engineering of Orally Available, Ultralong-Acting Insulin Analogues: Discovery of OI338 and OI320

Abstract

Recently, the first basal oral insulin (OI338) was shown to provide similar treatment outcomes to insulin glargine in a phase 2a clinical trial. Here, we report the engineering of a novel class of basal oral insulin analogues of which OI338, 10, in this publication, was successfully tested in the phase 2a clinical trial. We found that the introduction of two insulin substitutions, A14E and B25H, was needed to provide increased stability toward proteolysis. Ultralong pharmacokinetic profiles were obtained by attaching an albumin-binding side chain derived from octadecanedioic (C18) or icosanedioic acid (C20) to the lysine in position B29. Crucial for obtaining the ultralong PK profile was also a significant reduction of insulin receptor affinity. Oral bioavailability in dogs indicated that C18-based analogues were superior to C20-based analogues. These studies led to the identification of the two clinical candidates OI338 and OI320 (10 and 24, respectively).

Molecular and pharmacological characterization of insulin icodec: a new basal insulin analog designed for once-weekly dosing

“… 14 Insulin icodec was chemically modified by coupling the N- hydroxysuccinimide-activated side chain to the epsilon amino group of B29 lysine. 15 …”

Commemorating insulin's centennial: engineering insulin pharmacology towards physiology

“…In contrast to currently available basal insulin analogs that are primarily protracted in the s.c. tissue after injection, OI338 is based on protraction in the plasma compartment and the interstitial fluid [55]. Molecular engineering of OI338 combined enhanced proteolytic stability, that significantly improves bioavailability, with strong but reversible albumin binding and very low receptor affinity (500-fold reduced vs human insulin), leading to a half-life of~70 h in man [51,55,56]. Specifically, the ultra-long half-life was achieved by slowing receptor-mediated clearance through lowering the IR affinity by replacing two solvent-exposed aromatic amino acids (A14Glu and B25His) and by albumin binding through chemical modification of the ε-amino group of B29Lys with a side chain including a C18 fatty diacid moiety (Figure 2E) [56].…”

“…Molecular engineering of OI338 combined enhanced proteolytic stability, that significantly improves bioavailability, with strong but reversible albumin binding and very low receptor affinity (500-fold reduced vs human insulin), leading to a half-life of~70 h in man [51,55,56]. Specifically, the ultra-long half-life was achieved by slowing receptor-mediated clearance through lowering the IR affinity by replacing two solvent-exposed aromatic amino acids (A14Glu and B25His) and by albumin binding through chemical modification of the ε-amino group of B29Lys with a side chain including a C18 fatty diacid moiety (Figure 2E) [56]. Despite low in vitro potency, OI338 is still a full IR agonist and maintains in vivo efficacy, as demonstrated by whole-body glucose disposal under euglycemic clamp conditions in rats, pigs, and dogs [55].…”

Structural principles of insulin formulation and analog design: A century of innovation

“…(B) Insulin degludec has a more complex acyl modification, hexadecanedioic acid with γ-L-glutamyl spacer (blue). (C) Icodec (an ultra-basal analog) is further modified at Lys B29 with a C-20 diacid group connected through a 2xOEG-gGlu linker (blue) and has amino acid substitutions (Tyr B16 →His, Phe B25 →His, and Tyr A14 →Glu, red) [ 104 , 106 , 111 ]. (D) Investigational basal insulin F c fusion protein (BIF; LY3209590) comprises of an SCI fused to a human IgG 2 F c domain; the insulin moiety contains modifications of Glu B16 , His B25 , Gly B27 , Gly B28 , Gly B29 and Gly B30 fused to a human IgG 2 F c domain through a tandem (Gly4-Gln) peptide linker (tan) at the A-chain C terminus (A21).…”