ActRII Chimeras for Muscle and Bone Growth
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Solution Overview
Problem
Current treatments for muscular diseases, bone disorders, anemia, thrombocytopenia, neutropenia, myelofibrosis, fibrosis, pulmonary hypertension, and metabolic diseases are inadequate, and existing erythropoietin therapies are inconvenient and associated with side effects.
Innovation Solution
Development of polypeptides containing an extracellular activin receptor type II (ActRII) chimera, which can be fused with an Fc domain or other moieties to enhance stability and activity, promoting muscle and bone growth, increasing red blood cell production, and improving metabolic functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If erythropoietin therapies are used to treat anemia, then red blood cell production is improved, but treatment convenience deteriorates and side effects increase
Solution Approach 1:
The patent uses an activin receptor type II chimera as an intermediary molecule to block the action of myostatin and other activin ligands. This chimera acts as a decoy receptor that binds to the ligands, preventing them from interacting with endogenous receptors, thereby indirectly promoting muscle growth and potentially red blood cell production without directly administering erythropoietin
Solution Approach 2:
The invention modifies the receptor structure by creating chimeric proteins that combine extracellular domains of activin receptor type II with Fc regions of IgG antibodies. This structural parameter change extends the half-life of the therapeutic agent and enhances its binding affinity, improving treatment efficacy while reducing dosing frequency
2Reliability
If existing treatments for bone loss are used, then bone density may be maintained, but side effects and treatment complexity increase
Solution Approach 1:
The activin receptor type II chimera serves as an intermediary that blocks catabolic signaling pathways. By binding to myostatin and other activin ligands, the chimera prevents these molecules from activating osteoclasts and other catabolic processes, thereby protecting bone density without requiring direct osteogenic stimulation that carries side effects
Solution Approach 2:
The invention converts the harmful catabolic signaling of myostatin and activins into a beneficial effect. By using these ligands as targets for blockade, the therapy harnesses the body's own signaling molecules - when blocked, they prevent bone loss and muscle wasting, turning the presence of these potentially harmful molecules into an opportunity for protective therapy
3Reliability
If fibrosis treatments are administered, then disease progression is slowed, but treatment options remain limited and quality of life is not significantly improved
Solution Approach 1:
The activin receptor type II chimera exhibits multi-functionality by targeting a common signaling pathway (activin/myostatin receptor) that is involved in multiple diseases including fibrosis, muscular dystrophies, bone loss, and anemia. A single therapeutic agent can potentially address multiple conditions or work synergistically with other therapies, expanding treatment options beyond what is currently available for any single disease
Data Source
AI summary
The invention features polypeptides that include an extracellular ActRII chimera. In some embodiments, a polypeptide of the invention includes an extracellular ActRII chimera fused to an Fc domain or moiety. The invention also features pharmaceutical compositions and methods of using the polypeptides to treat diseases and conditions involving weakness or atrophy of muscles, bone damage, low red blood cell levels (e.g., anemia or blood loss), low platelet levels (e.g., thrombocytopenia), low neutrophil levels (e.g., neutropenia), fibrosis, metabolic disorders, pulmonary hypertension, and/or diseases and conditions that can be treated with erythropoietin or an erythropoiesis-stimulating agent.