Selective V1A Partial Agonist Peptide to Limit Organ Ischemia
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Solution Overview
Problem
Current treatments for ascites in cirrhosis, such as diuretics and paracentesis, do not address the underlying pathophysiology and become ineffective when the RAAS system is overactivated, leading to kidney failure and hepatorenal syndrome, while existing vasoconstrictors like terlipressin have limitations including short half-life, high dose side effects, and organ ischemia.
Innovation Solution
Development of a V1a receptor partial agonist peptide with a therapeutic index of at least 20, which can be administered subcutaneously without causing injection site necrosis, limits receptor activation, and minimizes V2 activity, combined with a V2 antagonist for improved efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If vasoconstrictors like terlipressin are used to reduce portal pressure and treat ascites, then splanchnic blood supply is reduced and portal pressure decreases, but organ ischemia and high dose side effects occur
Solution Approach 1:
The patent modifies the amino acid sequence of vasopressin to create analogs with altered receptor selectivity. Specifically, modifications at positions 6, 7, and 8 of the vasopressin sequence change the agonist activity profile to preferentially activate V1a receptors while minimizing V2 and V1b receptor activation, thereby reducing ischemic side effects while maintaining portal pressure reduction efficacy
Solution Approach 2:
The patent creates vasoconstrictor agents with localized action primarily in the splanchnic circulation through selective V1a receptor activation. The modified vasopressin analogs exhibit preferential binding to V1a receptors in splanchnic vessels, achieving localized vasoconstriction in the portal system while minimizing systemic vasoconstriction and renal artery constriction that cause ischemia
2Stress or pressure
If full V1a agonists are used to achieve maximum vasoconstriction effect, then portal pressure reduction is maximized, but therapeutic index decreases due to high dose side effects
Solution Approach 1:
The patent employs partial agonism at V1a receptors rather than full agonism. The modified vasopressin analogs produce submaximal vasoconstriction at V1a receptors compared to native vasopressin, which prevents excessive portal pressure reduction and associated side effects while maintaining clinically effective portal pressure control. This partial activation approach widens the therapeutic index by avoiding the steep dose-response curve of full agonists
3Quantity of substance
If V2 receptor activity is increased to enhance antidiuretic effect, then water reabsorption increases, but hyponatremia and edema occur
Solution Approach 1:
The patent extracts and isolates the V1a vasoconstrictor activity from the V2 antidiuretic activity of native vasopressin through selective amino acid modifications. The modified analogs have minimal V2 receptor agonist activity, effectively removing the harmful antidiuretic effect while preserving the beneficial portal vasoconstriction. This separation of functions allows treatment of portal hypertension without causing hyponatremia or worsening ascites through water retention
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The V1a receptor partial agonist peptide effectively treats conditions like cirrhosis, portal hypertension, and ascites by reducing splanchnic blood supply and portal pressure, while avoiding high dose side effects and maintaining renal function.
Implementation Method 1
Vasopressin acts on V1 (also called V1a, present mainly in blood vessels), V2, V3 (also called V1b, present mainly in the central nervous system (CNS)), and oxytocin-type receptors (OTR).
Implementation Method 2
vasopressin activates the V1 receptor (also called V1a, present mainly in blood vessels), resulting in vasoconstriction and an attenuation of nitric oxide (NO) synthesis; resulting in increased peripheral vascular resistance that raises arterial blood pressure
Implementation Method 3
vasopressin activates the V1 receptor (also called V1a, present mainly in blood vessels), resulting in vasoconstriction and an attenuation of nitric oxide (NO) synthesis
Implementation Method 4
the activation of the V2 receptor by vasopressin in the kidney increases the reabsorption of solute-free water to reverse hypertonicity
Data Source
AI summary
The present disclosure provides novel V1a partial agonists for partially activating a V1a receptor. The partial V1a agonist has a therapeutic index of at least 20 (e.g., at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 100). Also provided are method of treating liver fibrosis, cirrhosis, portal hypertension, ascites, esophageal varices, fundal varices, bleeding, arterial hypotension, and/or hepatorenal syndrome, including administering to a subject in need thereof a therapeutically effective dose of a composition including the V1a partial agonist(s) of the present disclosure, optionally in combination with a V2 antagonist.