Immunoassay for chromogranin A, antibodies and kit
Inventors
Stridsberg, Mats • Sommarin, Yngve
Assignees
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Publication Number
US-9322828-B2
Publication Date
2016-04-26
Expiration Date
Abstract
The invention relates to monoclonal antibodies which are reactive with an epitope in the polypeptide represented by amino acid sequence 236 to 251 or 264 to 279 of the human CGA amino acid sequence. The invention further relates to the use of these monoclonal antibodies in an immunoassay for CGA, to immunoreagents comprising any of these two antibodies, and to test kits for the determination of CGA containing immunoreagents based on both of the monoclonal antibodies.
Core Innovation
The invention relates to immunoassays for human Chromogranin A (CGA) and/or fragments thereof using a set of monoclonal antibodies that recognize two specified epitopes. One monoclonal antibody in the set is reactive with an epitope within amino acids 236 to 251 of human CGA (SEQ ID NO:2), and another monoclonal antibody in the set is reactive with an epitope within amino acids 264 to 279 of human CGA (SEQ ID NO:3).
The assay is preferably performed in a sandwich format, for example ELISA or RIA, to detect human CGA polypeptide and fragments thereof. The approach is directed to improving specificity and sensitivity by reducing false-positive/false-negative results caused by cross-reactive CGA fragments. The document further describes immunoreagent and kit formats, including capture and detection antibodies, labels, and solid-phase configurations, with examples including biotin/streptavidin linkage.
The disclosed embodiments include calibration curve evaluation and correlation studies against reference immunoassays. A high correlation factor (0.942) is reported versus a Dako polyclonal ELISA, while a weaker correlation factor (0.451) is reported versus a CIS-BIO monoclonal-based ELISA. Clinical sensitivity and specificity are reported across neuroendocrine tumor categories, including overall sensitivity of 60% and blood donor control specificity of 98%.
Claims Coverage
The document provides one independent claim, centered on a method for determining human Chromogranin A (CGA) or fragments by reacting a sample with monoclonal antibodies that recognize two distinct CGA epitope intervals and detecting binding of the set.
Dual-epitope monoclonal antibody set for CGA fragments
Reacting a sample with a set of monoclonal antibodies in which at least one monoclonal antibody is reactive with an epitope within amino acids 236 to 251 of human CGA (SEQ ID NO:2) and at least one other monoclonal antibody is reactive with an epitope within amino acids 264 to 279 of human CGA (SEQ ID NO:3).
Binding detection of antibody set to determine CGA comprising both epitopes
Detecting binding of the set of monoclonal antibodies to thereby detect human CGA polypeptide or fragments thereof comprising SEQ ID NO:2 and SEQ ID NO:3 in the sample.
The claim coverage focuses on detecting human CGA and/or fragments by using a monoclonal antibody set constrained to two defined epitope regions and detecting antibody binding as the basis for CGA detection.
Stated Advantages
Improved specificity and sensitivity compared with prior art.
Reduction of false-positive/false-negative results due to cross-reactive CGA fragments.
High correlation versus a Dako polyclonal ELISA (correlation factor 0.942).
Overall sensitivity of 60% and blood donor control specificity of 98%.
Documented Applications
Immunoassay determination of human Chromogranin A (CGA) for diagnostic assessment across neuroendocrine tumor categories.
Assessment using blood donor controls for specificity evaluation.
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