Compositions and methods related to diagnosis of prostate cancer

Abstract

Aspects of the disclosure relate to improved methods for predicting whether a prostate tissue biopsy obtained from a subject will contain detectable prostate cancer.

What is claimed is: 
     
         1 . A method of determining the probability that a prostate tissue biopsy obtained from a subject would contain detectable prostate cancer, the method comprising:
 i) subjecting a blood plasma sample of the subject to an immunoassay that measures a level of total prostate specific antigen (tPSA) in the blood plasma sample;   ii) if the tPSA level is above a threshold level, determining the probability that the prostate tissue biopsy would contain detectable prostate cancer by weighting the measured level of tPSA and a parameter indicative of whether the subject has had a prior biopsy of prostate tissue; and   iii) if the tPSA level is at or below the threshold level, subjecting the blood plasma sample to an immunoassay that measures levels of free prostate specific antigen (fPSA), intact prostate specific antigen (iPSA), and human kallikrein 2 (hK2) in the blood plasma sample, and determining the probability that the prostate tissue biopsy would contain detectable prostate cancer by weighting the measured levels of tPSA, fPSA, iPSA, and hK2 and a parameter indicative of whether the subject has had a prior biopsy of prostate tissue.   
     
     
         2 . A method of determining the probability that a prostate tissue biopsy obtained from a subject would contain detectable prostate cancer, the method comprising:
 i) subjecting a blood plasma sample of the subject to immunoassays that measure levels of free prostate specific antigen (fPSA), intact prostate specific antigen (iPSA), total prostate specific antigen (tPSA) and human kallikrein 2 (hK2); and   ii) determining the probability that the prostate tissue biopsy would contain detectable prostate cancer by weighting the measured levels of fPSA, iPSA, tPSA, and hK2 and a parameter indicative of whether the subject had a prior biopsy of prostate tissue.   
     
     
         3 . The method of  claim 2 , wherein the prostate cancer is a high grade prostate cancer. 
     
     
         4 . The method of  claim 2 , wherein the probability is further determined by weighting a parameter indicative of the subject's age. 
     
     
         5 . The method of  claim 2 , wherein the probability is further determined by weighting a parameter indicative of the outcome of a digital rectal examination performed on the subject. 
     
     
         6 . The method of  claim 2 , wherein the probability is further determined by weighting a cubic spline term based on the measured tPSA level and/or a cubic spline term based on the measured fPSA level. 
     
     
         7 . The method of  claim 2 , wherein the immunoassay that measures the level of fPSA comprises:
 contacting fPSA present in the blood plasma sample with a first capture antibody specific for fPSA under conditions in which the first capture antibody binds to fPSA, thereby producing a capture-antibody-fPSA complex; and   detecting the capture-antibody-fPSA complex using a first tracer.   
     
     
         8 . The method of  claim 7 , wherein the first tracer is a 5A10 antibody and/or the first capture antibody is a H117 antibody. 
     
     
         9 . The method of  claim 2 , wherein the immunoassay that measures the level of iPSA comprises:
 contacting iPSA present in the blood plasma sample with a second capture antibody specific for iPSA and nicked PSA, under conditions in which the second capture antibody binds at least to iPSA, thereby producing a capture-antibody-iPSA complex; and   detecting the capture-antibody-iPSA complex using a second tracer.   
     
     
         10 . The method of  claim 9 , wherein the immunoassay that measures the level of iPSA further comprises combining the capture-antibody-iPSA complex with the second tracer in a buffer having a pH of 6.5 to 7.0, such that the second tracer specifically binds to the capture-antibody-iPSA complex. 
     
     
         11 . The method of  claim 10 , wherein the second tracer comprises a 4D4 antibody. 
     
     
         12 . The method of  claim 11 , wherein the second capture antibody is a 5A10 Fab. 
     
     
         13 . The method of  claim 2 , wherein the immunoassay that measures the level of tPSA comprises:
 contacting tPSA present in the blood plasma sample with a third capture antibody specific for tPSA under conditions in which the third capture antibody binds to tPSA, thereby producing a capture-antibody-tPSA complex; and   detecting the capture-antibody-tPSA complex using a third tracer.   
     
     
         14 . The method of  claim 13 , wherein the third tracer comprises a H50 antibody and/or the third capture antibody is a H117 antibody. 
     
     
         15 . The method of  claim 2 , wherein the immunoassay that measures the level of hK2 comprises:
 contacting PSA in the blood plasma sample with blocking antibodies specific for PSA;   contacting hK2 present in the blood plasma sample with a fourth capture antibody specific for hK2 under conditions in which the fourth capture antibody binds to hK2, thereby producing a capture-antibody-hK2 complex; and   detecting the capture-antibody-hK2 complex using a fourth tracer.   
     
     
         16 . The method of  claim 15 , wherein the fourth tracer comprises a 7G1 antibody and/or the fourth capture antibody is a 6H10 F(ab) 2 . 
     
     
         17 . The method of  claim 15 , wherein the blocking antibodies comprise a 5F7 antibody, a 5H6 antibody, and a 2E9 antibody. 
     
     
         18 . The method of  claim 2 , wherein each or any capture antibody is bound to a solid support and/or each or any tracer comprises a Europium label. 
     
     
         19 . The method of  claim 2 , wherein the probability that the prostate tissue biopsy would contain detectable prostate cancer is 
       
         
           
             
               
                 
                   e 
                   
                     X 
                     ⁢ 
                     β 
                   
                 
                 
                   1 
                   + 
                   
                     e 
                     
                       X 
                       ⁢ 
                       β 
                     
                   
                 
               
               ; 
             
           
         
         wherein Xβ=β 0 +β 1 age+β 2 tpsa+β 3 sptpsa1+β 4 sptpsa2+β 5 fpsa+β 6 spfpsa1+β 7 spfpsa2+β 8 ipsa+β 9 hK2+β 10 dre neg +β 11 dre pos +β 12 priorbx, 
         wherein β 0 -β 12  are weighting coefficients, age is the age of the identified subject of (i) at blood draw, tpsa is concentration of tPSA in ng/mL, fpsa is concentration of fPSA in ng/mL, ipsa is concentration of iPSA in ng/mL, hK2 is concentration of hK2 in ng/mL, sptpsa1 is a first spline term for tPSA, sptpsa2 is a second spline term for tPSA, spfpsa1 is a first spline term for fPSA, spfpsa2 is a second spline term for fPSA, dre neg  is a value of 1 if a digital rectal examination has been confirmed as negative or a value of 0 otherwise, dre pos  is a value of 1 if a digital rectal examination has been confirmed as positive or a value of 0 otherwise, and priorbx is 0 if no prior biopsy and 1 if the identified subject of (i) had a prior biopsy; and 
         wherein β 0 -β 12  are different for determining the probability that a prostate tissue biopsy for the identified subject of (i) would contain high grade prostate cancer than β 0 -β 12  for determining the probability that a prostate tissue biopsy for the identified subject of (i) would contain any detectable prostate cancer. 
       
     
     
         20 . An immunoassay method that measures the level of iPSA in a sample, the method comprising:
 contacting iPSA present in the sample with a capture antibody specific for iPSA and nicked PSA under conditions in which the capture antibody binds at least to iPSA, thereby producing a capture-antibody-iPSA complex;   combining the capture-antibody-iPSA complex with a tracer in a buffer having a pH in a range of 6.5 to 7.0 such that the tracer binds to the capture-antibody-iPSA complex; and   detecting the tracer bound to the capture-antibody-iPSA complex.