ABSTRACT
To realize the medicinal potential of peptide toxins, naturally occurring disulfide-rich peptides, as ion channel antagonists, more efficient pharmaceutical optimization technologies must be developed. Here, we show that the therapeutic properties of multiple cysteine toxin peptides can be rapidly and substantially improved by combining direct chemical strategies with high-throughput electrophysiology. We applied whole-molecule, brute-force, structure-activity analoging to ShK, a peptide toxin from the sea anemone Stichodactyla helianthus that inhibits the voltage-gated potassium ion channel Kv1.3, to effectively discover critical structural changes for 15× selectivity against the closely related neuronal ion channel Kv1.1. Subsequent site-specific polymer conjugation resulted in an exquisitely selective Kv1.3 antagonist (>1000× over Kv1.1) with picomolar functional activity in whole blood and a pharmacokinetic profile suitable for weekly administration in primates. The pharmacological potential of the optimized toxin peptide was demonstrated by potent and sustained inhibition of cytokine secretion from T cells, a therapeutic target for autoimmune diseases, in cynomolgus monkeys.
Subject(s)
Cnidarian Venoms/chemistry , Kv1.3 Potassium Channel/antagonists & inhibitors , Peptides/chemistry , Polyethylene Glycols/chemistry , Animals , CHO Cells , Cnidarian Venoms/pharmacokinetics , Cnidarian Venoms/pharmacology , Cricetulus , Crystallography, X-Ray , Dogs , HEK293 Cells , Humans , Interferon-gamma/blood , Interferon-gamma/metabolism , Interleukin-17/blood , Interleukin-17/metabolism , Interleukin-2/blood , Interleukin-2/metabolism , Kv1.1 Potassium Channel/antagonists & inhibitors , Macaca fascicularis , Male , Mice , Molecular Docking Simulation , Patch-Clamp Techniques , Peptides/pharmacokinetics , Peptides/pharmacology , Rats, Sprague-Dawley , Species Specificity , Stereoisomerism , Structure-Activity Relationship , T-Lymphocytes/drug effects , T-Lymphocytes/metabolismABSTRACT
Antagonism of the calcitonin gene-related peptide (CGRP) receptor may be a useful approach for migraine treatment. Selective PEGylated peptide antagonists to the CGRP receptor are described, derived from CGRP(8-37) with polymer derivatization at an engineered lysine-25 residue. Potent PEGylated peptides with improved pharmacokinetics were identified through peptide side-chain modification to mitigate metabolic liabilities. PEGylated Ac-Trp-[Cit(11,18),hArg(24),Lys(25),Asp(31),Pro(34),1-Nal(35)]CGRP(8-37)-NH2, 9, elicits a dose-dependent reduction of intradermal CGRP-induced local blood flow in rodents with an ED50 of 0.52 mg kg(-1) without any overt adverse effects.
