Assay to measure midkine or pleiotrophin level for diagnosing a growth
Inventors
Baron, Jeffrey • Jee, Youn Hee
Assignees
US Department of Health and Human Services
Publication Number
US-9658233-B1
Publication Date
2017-05-23
Expiration Date
2033-11-15
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Abstract
The invention provides methods and kits for diagnosing a growth in a subject by providing a sample of a growth taken from a subject, determining the level of midkine or pleiotrophin in the sample by an immunoassay, and comparing the level of midkine or pleiotrophin determined from the sample with a control. An increased level of midkine or pleiotrophin in the sample as compared to the control is diagnostic of a malignant growth, whereas an equivalent or decreased level of midkine or pleiotrophin in the sample as compared to the control is diagnostic of a benign growth.
Core Innovation
The invention provides methods and kits for diagnosing a growth in a subject by analyzing a sample of the growth to determine the level of midkine or pleiotrophin using an immunoassay and comparing this level with a control. An increased level of midkine or pleiotrophin in the sample as compared to the control is diagnostic of a malignant growth, while an equivalent or decreased level is diagnostic of a benign growth.
The invention addresses the problem that current cancer diagnostic methods are often highly invasive and less invasive methods may be unreliable. Improved, sensitive, and less invasive methods for cancer detection are desired. Midkine and pleiotrophin, heparin-binding growth factors, have expression levels increased in various cancers, suggesting their utility as markers for diagnosis.
The invention provides detailed methods including immunoassays such as sandwich ELISA for measuring midkine or pleiotrophin levels in samples obtained by various biopsy techniques including fine needle aspiration. Normalization of midkine or pleiotrophin levels to proteins such as thyroglobulin allows distinguishing benign from malignant growths. Kits comprising specific antibodies and instructional materials facilitate these diagnostic methods.
Claims Coverage
The patent includes one independent claim outlining a method for diagnosing thyroid growth malignancy by determining midkine and thyroglobulin protein levels and their ratio, and using this ratio for diagnostic and treatment decisions.
Diagnosis of thyroid growth malignancy using midkine to thyroglobulin ratio
A method involving providing a thyroid tissue sample, determining midkine and thyroglobulin protein concentrations by immunoassay, calculating their ratio (MK/Tg), comparing this ratio to a control derived from benign growths, and diagnosing malignancy upon an increased ratio.
Treatment decision based on diagnostic ratio
Performing thyroidectomy on the subject when the diagnosis indicates a malignant growth based on the increased MK/Tg ratio.
Use of sandwich ELISA with specific antibody
Employing a sandwich enzyme-linked immunosorbent assay comprising contacting the sample with an antibody specifically binding to human midkine protein for detection.
Inclusion of labeled antibody in assay
Using an antibody conjugated to labels such as biotin, radionuclide, fluorescent molecule, chemiluminescent molecule, or enzyme to facilitate detection in the assay.
Use of polymer to enhance assay sensitivity
Incorporating a polymer, specifically poly-L-lysine, into the antibody solution during antigen binding to increase sensitivity of the immunoassay.
Specific polymer concentration
Utilizing poly-L-lysine at a concentration of 10 μg/mL in the antibody solution during the immunoassay.
The claims collectively cover a method of diagnosing and treating thyroid growths by measuring and comparing the midkine to thyroglobulin protein concentration ratio using a sensitive immunoassay enhanced by poly-L-lysine, with provision for treatment via thyroidectomy upon diagnosis of malignancy.
Stated Advantages
High sensitivity of midkine assay enabling determination in small samples such as fine needle aspirates.
Increased sensitivity by inclusion of polymers like poly-L-lysine in the immunoassay improving antibody binding and reducing nonspecific interactions.
Ability to distinguish malignant from benign growths based on normalized midkine or pleiotrophin levels.
Reduced need for highly invasive diagnostic procedures by employing less invasive sampling and immunoassay techniques.
Documented Applications
Diagnosing whether a growth, including thyroid nodules and various cancers, is benign or malignant by measuring levels of midkine or pleiotrophin in tissue samples.
Specifically diagnosing papillary thyroid cancer using midkine or pleiotrophin levels normalized to thyroglobulin in fine needle aspirate samples.
Using the method to assess various cancers including acute lymphoblastic leukemia, breast cancer, colon cancer, pancreatic cancer, and many others as listed in the document.
Guiding treatment decisions such as performing thyroidectomy based on diagnostic results from midkine to thyroglobulin ratios.
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