IL-2 Conjugate Receptor Selectivity for Cancer Therapy
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Solution Overview
Problem
Existing IL-2 therapies for cancer treatment are limited by severe side effects such as vascular leak syndrome due to interactions with IL-2Rαβγ-expressing cells, and manufacturing IL-2 proteins with additional cysteine residues for preferential IL-2Rβγ binding is challenging due to aggregation issues.
Innovation Solution
An IL-2 protein sequence with an N-terminal alanine residue and a cysteine (Cys*) is developed, enhancing expression yields and preferential binding to IL-2Rβγ, reducing IL-2Rα interaction, and potentially minimizing side effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IL-2 is administered at high doses to stimulate antitumor efficacy, then cytotoxic lymphocyte expansion is enhanced, but severe side effects including vascular leak syndrome occur
Solution Approach 1:
The patent introduces a point mutation (K34C) at a specific local position in the IL-2 molecule to alter its binding properties. This localized modification changes the quality of interaction with IL-2Rβγ versus IL-2Rαβγ, enabling selective activation of antitumor pathways while avoiding harmful interactions with other cell types, thus resolving the contradiction between efficacy and side effects
Solution Approach 2:
The patent changes the binding affinity parameters of IL-2 by introducing the K34C mutation and subsequent disulfide bond formation. This parameter change shifts the equilibrium from high-affinity binding to all IL-2R types toward preferential binding to IL-2Rβγ, maintaining effective concentrations for cytotoxic lymphocyte activation while reducing concentrations that cause vascular leak syndrome
2Reliability
If cysteine residues are added to IL-2 for preferential IL-2Rβγ binding, then binding selectivity is improved, but protein aggregation increases during manufacturing
Solution Approach 1:
The patent extracts the problematic free cysteine thiol group from the K34C mutation by forming an intramolecular disulfide bond with the native Cys87 residue. This removes the aggregation-prone free thiol while preserving the structural and binding benefits of the introduced cysteine, resolving the manufacturing stability issue while maintaining binding selectivity
Solution Approach 2:
The intramolecular disulfide bond acts as an intermediary that connects the introduced Cys34 to the native Cys87. This intermediary structure stabilizes the protein conformation and prevents intermolecular aggregation while maintaining the desired binding properties, thus enabling successful manufacturing
3Reliability
If wild type IL-2 binds to IL-2Rαβγ-expressing cells, then high affinity binding is achieved, but vascular leak syndrome is induced
Solution Approach 1:
The K34C mutation at position 34 locally alters the binding interface of IL-2, changing its quality of interaction with IL-2Rα versus IL-2Rβγ. This local modification reduces affinity for IL-2Rαβγ (thereby preventing vascular leak syndrome) while maintaining or enhancing affinity for IL-2Rβγ, resolving the contradiction between binding affinity and harmful effects
Data Source
AI summary
The present invention relates to an IL-2 protein sequence of the formula Ala-SEQ A-Cys*-SEQ B (I), wherein SEQ A has at least 94% sequence identity to SEQ ID NO:1; SEQ B has at least 94% sequence identity to SEQ ID NO:2; Ala is an alanine residue; and Cys* is a cysteine residue; to conjugates thereof and their uses in the treatment of cancer.