CTLA4-Ig Fusion Protein Formulation for Aggregation Control
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Solution Overview
Problem
Fusion proteins, such as CTLA4-Ig, are prone to instability due to aggregation, fragmentation, and oxidation, which affects their bioactivity and stability under various environmental conditions, necessitating the development of a suitable formulation that maintains colloidal stability and reduces these degradation pathways.
Innovation Solution
A stable pharmaceutical formulation of CTLA4-Ig fusion protein comprising a combination of histidine, sugar, and surfactant, optionally with pharmaceutically acceptable excipients, is developed, which is added during the tangential flow filtration process to enhance stability and colloidal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fusion protein is formulated in solution, then it can be administered conveniently, but it undergoes aggregation and degradation leading to instability
Solution Approach 1:
The patent introduces multiple excipients (sugars like sucrose or trehalose, amino acids like arginine or lysine, surfactants like polysorbate 20 or 80, and buffers) as intermediary substances that mediate between the protein and the aqueous environment. These excipients form protective complexes with the protein surface, preventing direct interaction with destabilizing factors in solution while maintaining solubility and administerability.
Solution Approach 2:
The formulation creates a composite system where the fusion protein is combined with multiple stabilizing excipients in specific concentrations. This composite formulation provides synergistic protection: sugars prevent aggregation through preferential exclusion, amino acids reduce deamidation, surfactants prevent surface adsorption, and buffers maintain pH stability, collectively preserving protein integrity in solution.
2Productivity
If fusion protein concentration is increased to reduce dosage volume, then treatment efficiency improves, but aggregation rate increases rapidly
Solution Approach 1:
At high protein concentrations, excipients act as intermediaries that occupy interfacial spaces between protein molecules. Surfactants adsorb at protein-protein interfaces, while sugars form hydration shells, preventing direct protein-protein contact that would lead to aggregation. This allows maintaining high therapeutic doses without proportional increase in aggregation.
Solution Approach 2:
The formulation optimizes multiple parameters simultaneously: pH (6.0-8.0) to minimize charge interactions, ionic strength to control electrostatic forces, and excipient concentrations to provide steric and electrostatic repulsion. These parameter adjustments collectively reduce the aggregation propensity even at high protein concentrations up to 100 mg/mL or higher.
3Stability of the object's composition
If storage temperature is reduced to maintain stability, then protein degradation decreases, but logistics and distribution complexity increases
Solution Approach 1:
The formulation incorporates stabilizing excipients that provide a protective cushion against thermal stress before exposure occurs. Sugars form glassy matrices or hydration shells that restrict protein mobility and conformational changes during temperature fluctuations. Amino acids and surfactants pre-occupy potential aggregation sites, creating a buffer zone that prevents degradation during temperature excursions in the cold chain.
Solution Approach 2:
The patent enables use of inexpensive, readily available excipients (common sugars, amino acids, and surfactants) that provide robust stabilization without requiring ultra-cold storage. This replaces complex expensive cryopreservation systems with simple refrigerated or even ambient temperature storage, reducing logistics complexity while maintaining adequate stability through the protective excipient system.
4Quantity of substance
If pH is adjusted to optimize solubility, then protein dissolves better, but deamidation and oxidation reactions increase
Solution Approach 1:
Amino acids (arginine, lysine, glycine) and buffers act as intermediaries that control the chemical environment. They buffer pH to maintain optimal solubility while minimizing the catalytic effect of extreme pH on deamidation. These excipients also chelate metal ions that could catalyze oxidation, and compete for reactive intermediates, thereby protecting the protein from chemical degradation even at pH values that maximize solubility.
Data Source
AI summary
The present invention discloses a stable pharmaceutical formulation of a fusion protein, wherein the formulation contains buffer, sugar, amino acid and surfactant, and optionally includes salts. The disclosed fusion protein formulations are liquid formulations that are also suitable for lyophilization.