Activatable IL-2 Fusion Proteins for Tumor-Selective Cytokine Release
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Solution Overview
Problem
Cytokines, such as IL-2, have short serum half-lives and high potency, leading to undesirable systemic effects and toxicities when administered therapeutically, limiting their clinical use in treating tumors due to the inability to effectively target and control their activity.
Innovation Solution
Development of fusion proteins with attenuated IL-2-receptor activating activity and protease-cleavable linkers that are selectively cleaved at the tumor site, extending serum half-life and targeting cytokine activity to the tumor microenvironment, reducing systemic toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cytokines such as IL-2 are administered therapeutically to treat tumors, then antitumoral activity is improved, but systemic toxicity and undesirable effects increase due to short serum half-life and high potency
Solution Approach 1:
The cytokine molecule is divided into two functional parts: a blocking moiety that masks the active site and a cytokine portion that provides the biological activity. This segmentation allows the cytokine to be inactive during circulation (reducing toxicity) and become active only at the target site (maintaining efficacy).
Solution Approach 2:
A blocking moiety acts as an intermediary element that temporarily masks the cytokine's active site during circulation. This blocking moiety is removed or inactivated at the target site, allowing the cytokine to exert its therapeutic effect only where needed, thereby reducing systemic toxicity while maintaining antitumoral activity.
2Productivity
If cytokines are administered at high doses to achieve therapeutic effect, then tumor treatment efficacy is improved, but systemic side effects and toxicities worsen
Solution Approach 1:
The cytokine is designed with a blocking moiety that masks its activity during circulation, creating a local difference between the circulating state (inactive, low toxicity) and the target site state (active, high efficacy). This local quality control allows high effective concentration at the tumor site without proportionally increasing systemic toxicity.
Solution Approach 2:
The invention changes the activation state parameter of the cytokine from always active to conditionally active. By controlling the blocking moiety's presence or absence, the cytokine's biological activity parameter can be switched on or off, allowing high efficacy at the target while maintaining low systemic exposure and reduced side effects.
3Reliability
If cytokine activity is enhanced to improve tumor response, then therapeutic benefit is improved, but ability to control and target activity specifically to tumor microenvironment worsens
Solution Approach 1:
The cytokine's activity state is made dynamic rather than static. The blocking moiety can be removed or inactivated in response to tumor-specific conditions (such as protease presence in the tumor microenvironment), allowing the cytokine to transition from inactive to active state dynamically. This provides temporal and spatial control over cytokine activity, enhancing therapeutic benefit while improving targeting capability.
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 fusion proteins enable effective tumor treatment with limited cytokine activity to the tumor microenvironment, reducing toxicity and enhancing therapeutic efficacy while maintaining similar pharmacokinetic properties to naturally occurring cytokines.
Implementation Method 1
protease-cleavable linkers that are selectively cleaved at the tumor site
Data Source
AI summary
The disclosure features fusion proteins that are conditionally active variants of IL-2. In one aspect, the full-length polypeptides of the invention have reduced or minimal cytokine-receptor activating activity even though they contain a functional cytokine polypeptide. Upon activation, e.g., by cleavage of a linker that joins a blocking moiety, e.g., a steric blocking polypeptide, in sequence to the active cytokine, the cytokine can bind its receptor and effect signaling.