Methods for detecting neutralizing antibodies to parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) analog
The present disclosure is directed to methods (e.g., in vitro methods) for detecting the presence of neutralizing antibodies to PTH or PTHrP analog in a sample. The in vitro method comprises the steps of obtaining a sample from a subject; contacting the sample with a cell; measuring cyclic adenosine monophosphate (cAMP) levels; and detecting the presence of neutralizing antibodies when cAMP levels are reduced relative to a negative control sample without neutralizing antibodies. An in vitro method of detecting the presence of neutralizing antibodies in a sample from a subject treated with Abaloparatide, is also provided. Further provided herein is a kit for carrying out the methods described herein comprising components required to carry out the obtaining, contacting, measuring and detecting steps and instructions for use.
1. An in vitro method for detecting the presence of neutralizing antibodies to abaloparatide in a serum sample from a subject treated with abaloparatide, the method comprising:
obtaining the serum sample from the subject;
preincubating the serum sample with a predetermined amount of abaloparatide for a period of at least 30 minutes;
contacting the preincubated serum sample with a population of cells or a cell, wherein the cell or cells are rat epithelial cell line UMR-106, and wherein contacting comprises incubating the cell or cells with the serum sample for a period of time;
measuring cyclic adenosine monophosphate (cAMP) levels in the serum sample by a competitive immunoassay utilizing an electrochemiluminescent detection method; and
detecting the presence of neutralizing antibodies indicated by reduced cAMP levels relative to a negative control sample which does not include neutralizing antibodies.
2. The method of claim 1 , wherein incubating the cell or cells with the serum sample comprises adding about 40 microliters of a suspension of cells at a cell density of about 106 cells/mL to the serum sample, wherein the incubating is performed at room temperature, and wherein the incubating is performed for 1 to 2 hours.
3. The method of claim 1 , wherein the predetermined amount of abaloparatide is a concentration of abaloparatide in the serum sample in a range from 100 to 500 pg/mL.
4. The method of claim 1 , wherein the predetermined amount of abaloparatide is a concentration in the serum sample of 600 pg/mL.
5. The method of claim 1 , further comprising lysing the cell or cells prior to the measuring step.
6. The method of claim 5 , wherein lysing the cell or cells comprises incubating the cell or cells with a lysis buffer at room temperature for a time period of about 5 minutes to about 30 minutes.
7. The method of claim 1 , further comprising incubating the cell or cells with a cell permeable cAMP-specific phosphodiesterase inhibitor prior to the contacting step.
8. The method of claim 7 , wherein the cAMP-specific phosphodiesterase inhibitor is 4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone.
9. The method of claim 1 , further comprising serum-starving the cell or cells for a period of time in a range from 4 hours to 48 hours prior to the contacting step.
10. The method of claim 9 , wherein the period of time is selected from the group consisting of 4 hours to 24 hours, 4 hours to 16 hours, 4 hours to 12 hours, and 6 hours to 12 hours.
11. The method of claim 1 , wherein the serum sample is from a human subject.
12. A kit for carrying out the method of claim 1 , comprising components required to carry out the obtaining, preincubating, contacting, measuring, and detecting steps and instructions for use.