Radiolabeling kit and binding assay

Abstract

Antibody binding assays and radiolabeling kits are disclosed for radiolabeling and testing therapeutic antibodies in the commercial setting. In particular, the kits are designed for making and evaluating radiolabeled anti-CD20 conjugates to be used for the treatment and imaging of B cell lymphoma tumors. All kit reagents are sterile and are designed to achieve a high level of antibody radiolabeling and product stability with results which are highly reproducible.

What is claimed:  
     
         1 . A kit for radiolabeling an anti-CD20 antibody before administration to a patient comprising: 
 (i) a vial containing a chelator-conjugated antibody,    (ii) a vial containing formulation buffer for stabilizing and administering the radiolabeled antibody to a patient, and    (iii) instructions for radiolabeling the antibody,    wherein said vial components are supplied in such an amount and at such a concentration that when they are combined with a radiolabel according to the kit instructions, no further purification of the labeled antibody is required before administration to said patient.    
     
     
         2 . The radiolabeling kit of  claim 1 , wherein the antibody is a chimeric anti-CD20 antibody.  
     
     
         3 . The radiolabeling kit of  claim 1 , wherein the chelator is selected from the group consisting of MX-DTPA, phenyl-DTPA, benzyl-DTPA, CHX-DTPA and DOTA.  
     
     
         4 . The radiolabeling kit of  claim 1  further comprising a vial containing a buffer for adjusting the pH of the radioisotope.  
     
     
         5 . The radiolabeling kit of  claim 4 , wherein the buffer is a sodium acetate solution.  
     
     
         6 . The radiolabeling kit of  claim 1  further comprising a reaction vial.  
     
     
         7 . The radiolabeling kit of  claim 3 , wherein the chelator is MX-DTPA.  
     
     
         8 . The radiolabeling kit of  claim 1 , wherein the antibody is 2B8.  
     
     
         9 . The radiolabeling kit of  claim 8 , wherein the chelator-conjugated antibody is 2B8-MX-DTPA.  
     
     
         10 . The kit of  claim 1  wherein the antibody conjugate is supplied at a concentration of about 0.5 to 30 mg/ml.  
     
     
         11 . The radiolabeling kit of  claim 5  wherein the sodium acetate solution is at a concentration of 10 to 1000 mM.  
     
     
         12 . The radiolabeling kit of  claim 11  wherein the sodium acetate solution is at a concentration of 50 mM.  
     
     
         13 . The radiolabeling kit of  claim 1  wherein the formulation buffer comprises a radioprotectant and non-protein-conjugated chelator.  
     
     
         14 . The radiolabeling kit of  claim 13  wherein the radioprotectant is selected from the group consisting of human serum albumin (HSA), ascorbate, ascorbic acid, phenol, sulfites, glutathione, cysteine, gentisic acid, nicotinic acid, ascorbyl palmitate, HOP(:O)H 2 , glycerol, sodium formaldehyde sulfoxylate, Na 2 S 2 O 5 , Na 2 S 2 O 3 , and SO 2 .  
     
     
         15 . The radiolabeling kit of  claim 14  wherein the radioprotectant is HSA.  
     
     
         16 . The radiolabeling kit of  claim 13  wherein the unconjugated chelator is DTPA or EDTA.  
     
     
         17 . The radiolabeling kit of  claim 15  wherein the HSA is at a concentration of about 1 to 25% (w/v).  
     
     
         18 . The radiolabeling kit of  claim 17  wherein the concentration of HSA is about 7.5% (w/v).  
     
     
         19 . The radiolabeling kit of  claim 14  wherein the radioprotectant is ascorbate.  
     
     
         20 . The radiolabeling kit of  claim 19  wherein the ascorbate is at a concentration of about 1 to 100 mg/ml.  
     
     
         21 . The radiolabeling kit of  claim 1  wherein the radioisotope is  111 In chloride.  
     
     
         22 . The radiolabeling kit of  claim 1  wherein the radioisotope is  90 Y chloride.  
     
     
         23 . A formulation buffer for administering a radiolabeled chelator-conjugated antibody to a patient comprising: 
 (i) a physiological salt solution;    (ii) a radioprotectant; and    (iii) non-protein conjugated chelator.    
     
     
         24 . The formulation buffer of  claim 23  wherein the radioprotectant is selected from the group consisting of HSA, ascorbate, ascorbic acid, phenol, sulfites, glutathione, cysteine, gentisic acid, nicotinic acid, ascorbyl palmitate, HOP(:O)H 2 , glycerol, sodium formaldehyde sulfoxylate, Na 2 S 2 O 5 , Na 2 S 2 O 3 , and SO 2 .  
     
     
         25 . The formulation buffer of  claim 23  wherein the chelator is DTPA.  
     
     
         26 . The formulation buffer of  claim 24  wherein the radioprotectant is HSA.  
     
     
         27 . The formulation buffer of  claim 24  wherein the radioprotectant is ascorbate.  
     
     
         28 . The formulation buffer of  claim 26  wherein the concentration of human serum albumin is about 1 to 25% (w/v).  
     
     
         29 . The formulation buffer of  claim 28  wherein the HSA concentration is about 7.5%.  
     
     
         30 . The formulation buffer of  claim 25  wherein the concentration of DTPA is about 1 mM.  
     
     
         31 . The formulation buffer of  claim 27  wherein the concentration of ascorbate is about 1 to 100 mg/mL.  
     
     
         32 . A method for radiolabeling a chelator-conjugated anti-CD20 antibody for administration to a patient comprising 
 (i) mixing chelator-conjugated antibody with a solution containing a radiolabel;    (ii) incubating the mixture for an appropriate amount of time at appropriate temperature; and    (iii) diluting the labeled antibody to an appropriate concentration in formulation buffer, such that said radiolabeled antibody may be administered directly to the patient without further purification.    
     
     
         33 . The method of  claim 32  wherein the antibody is a chimeric anti-CD20 antibody.  
     
     
         34 . The method of  claim 32  wherein the anti-CD20 antibody is 2B8-MX-DTPA.  
     
     
         35 . The method of  claim 32  wherein the formulation buffer contains physiological saline, a radioprotectant, and unconjugated chelator.  
     
     
         36 . The method of  claim 35  wherein the radioprotectant is selected from the group consisting of human serum albumin (HSA), ascorbate, ascorbic acid, phenol, sulfites, glutathione, cysteine, gentisic acid, nicotinic acid, ascorbyl palmitate, HOP(:O)H 2 , glycerol, sodium formaldehyde sulfoxylate, Na 2 S 2 O 5 , Na 2 S 2 O 3 , and SO 2 .  
     
     
         37 . The method of  claim 35  wherein the unconjugated chelator is DTPAor EDTA.  
     
     
         38 . The method of  claim 32  wherein the solution containing the radiolabel is adjusted to a pH of about 3 to 6 before it is mixed with the chelator-conjugated antibody.  
     
     
         39 . The method of  claim 38  wherein the pH is adjusted with a low metal sodium acetate solution.  
     
     
         40 . The method of  claim 39  wherein the sodium acetate is at a concentration of about 10 to 1000 mM.  
     
     
         41 . The method of  claim 32  wherein the radiolabel is  111 In chloride.  
     
     
         42 . The method of  claim 41  wherein the volume quantity of  111 In chloride used is about 4-6 mCi divided by the radioactivity concentration at the time of labeling.  
     
     
         43 . The method of  claim 41  wherein about 1 ml of chelator-conjugated antibody at a concentration of about 0.5 to 30 mg/ml is mixed with the radiolabel solution.  
     
     
         44 . The method of  claim 43  wherein the mixture is incubated for between about 30 seconds and 60 minutes.  
     
     
         45 . The method of  claim 44  wherein formulation buffer is added in an amount necessary to achieve a total final volume of about 10 ml to about 50 ml.  
     
     
         46 . The method of  claim 32  wherein the radiolabel is  90 Y chloride.  
     
     
         47 . The method of  claim 46  wherein the volume quantity of  90 Y chloride used is between about 5 to 100 mCi divided by the radioactivity concentration at the time of labeling.  
     
     
         48 . The method of  claim 47  wherein the volume quantity of  90 Y chloride used is about 45 mCi divided by the radioactivity concentration at the time of labeling.  
     
     
         49 . The method of  claim 46  wherein about 1 to 2 ml of MX-DTPA-conjugated antibody at a concentration of about 0.5 to 30 mg/ml is mixed with the radiolabel solution.  
     
     
         50 . The method of  claim 49  wherein the mixture is incubated for a time between about 30 seconds to 60 minutes.  
     
     
         51 . The method of  claim 50  wherein formulation buffer is added in an amount necessary to achieve a total final volume of about 10 ml to about 50 ml.  
     
     
         52 . A binding assay and radiolabeling kit for radiolabeling an anti-CD20 antibody and determining the percent binding of the radiolabeled antibody to its target cell before administering the antibody to a patient, comprising the following components: 
 (i) at least one vial of fixed or lyophilized antigen-positive cells;    (ii) a vial containing a chelator-conjugated antibody;    (iii) a vial containing formulation buffer; and    (iv) instructions for radiolabeling the antibody,    wherein said vial components are supplied in such an amount and at such a concentration that when they are combined with a radiolabel according to the kit instructions, no further purification of the labeled antibody is required before administration to said patient.    
     
     
         53 . The binding assay and radiolabeling kit of  claim 52 , wherein said antibody is a chimeric anti-CD20 antibody.  
     
     
         54 . The binding assay and radiolabeling kit of  claim 52  further comprising a vial containing a buffer for adjusting the pH of the radiolabel.  
     
     
         55 . The binding assay and radiolabeling kit of  claim 52  wherein the formulation buffer is phosphate buffered saline comprising a radioprotectant and unconjugated chelator.  
     
     
         56 . The binding assay and radiolabeling kit of  claim 52 , wherein the antigen positive cells are CD20-positive cells.  
     
     
         57 . The binding assay and radiolabeling kit of  claim 56  wherein the CD20-positive cells are SB cells (ATCC # CCL 120).  
     
     
         58 . The binding assay and radiolabeling kit of  claim 52  further comprising at least one vial of antigen-negative cells.  
     
     
         59 . The binding assay and radiolabeling kit of  claim 58 , wherein said antigen-negative cells are CD20-negative cells.  
     
     
         60 . The binding assay and radiolabeling kit of  claim 59  wherein said CD20-negative cells are HSB cells (ATCC # CCL120.1).  
     
     
         61 . A binding assay kit for determining the percent binding of a radiolabeled anti-CD20 antibody to its target cell comprising at least one vial of fixed or lyophilized antigen-positive cells.  
     
     
         62 . The binding assay kit of  claim 61 , further comprising a control anti-CD20 antibody.  
     
     
         63 . The binding assay kit of  claim 62  wherein the CD20-positive cells are SB cells (ATCC # CCL 120).  
     
     
         64 . The binding assay kit of  claim 61  further comprising antigen-negative cells.  
     
     
         65 . The binding assay kit of  claim 64 , wherein said cells are CD20-negative.  
     
     
         66 . The binding assay kit of  claim 65  wherein said CD20-negative cells are HSB cells (ATCC # CCL120.1).  
     
     
         67 . A binding assay for determining the percent binding of a radiolabeled antibody to its target cell, comprising: 
 (i) mixing and incubating at least one aliquot of a radiolabeled antibody with at least one aliquot of antigen-positive cells;    (ii) mixing and incubating at least one aliquot of a radiolabeled antibody identical to the aliquot of step (i) with at least one aliquot of dilution buffer of the same volume as the aliquot of antigen-positive cells in step (i) as a control;    (iii) pelleting the cells by centrifugation;    (iv) measuring the radioactivity in the supernatant of the pelleted cells and the control; and    (v) comparing the quantity of radioactivity in the cell supernatant to the quantity of radioactivity in the control.    
     
     
         68 . The binding assay of  claim 67  wherein said antibody is a CD20 antibody.  
     
     
         69 . The binding assay of  claim 68  wherein the anti-CD20 antibody is 2B8.  
     
     
         70 . The binding assay of  claim 67  wherein said antigen is CD20.  
     
     
         71 . The binding assay of  claim 70  wherein said CD20 positive cells are SB cells (ATCC # CCL 120).  
     
     
         72 . The binding assay of  claim 67  further comprising 
 (i) mixing at least one aliquot of the radiolabeled antibody with at least one aliquot of antigen-negative cells;  
 (ii) pelleting the antigen-negative cells by centrifugation;  
 (iv) measuring the radioactivity in the supernatant of the antigen-negative pelleted cells; and  
 (v) comparing the quantity of radioactivity in the antigen-negative cell supernatant to the quantity of radioactivity in the supernatant of the antigen-positive cell supernatant and the control.  
 
     
     
         73 . The binding assay of  claim 72  wherein said antigen negative cells are CD20-negative.  
     
     
         74 . The binding assay of  claim 73  wherein said CD20 negative cells are HSB cells (ATCC # CCL 120.1).  
     
     
         75 . A binding assay for determining the percent binding of a radiolabeled antibody to its target cell, comprising: 
 (i) mixing at least one aliquot of a radiolabeled antibody with at least one aliquot of antigen-positive cells;    (ii) mixing at least one aliquot of the radiolabeled antibody identical to the aliquot of step (i) with at least one aliquot of dilution buffer of the same volume as the aliquot of antigen-positive cells in step (i) as a control;    (iii) pelleting the cells by centrifugation;    (iv) measuring the radioactivity in the supernatant of the pelleted cells and the control; and    (v) comparing the quantity of radioactivity in the cell supernatant to the quantity of radioactivity in the control;    wherein said assay is performed using the binding assay and radiolabeling kit of  claim 52 .    
     
     
         76 . A binding assay for determining the percent binding of a radiolabeled antibody to its target cell , comprising: 
 (i) mixing at least one aliquot of a radiolabeled antibody with at least one aliquot of antigen-positive cells;    (ii) mixing at least one aliquot of a radiolabeled antibody identical to the aliquot of step (i) with at least one aliquot of dilution buffer of the same volume as the aliquot of antigen-positive cells in step (i) as a control;    (iii) pelleting the cells by centrifugation;    (iv) measuring the radioactivity in the supernatant of the pelleted cells and the control; and    (v) comparing the quantity of radioactivity in the cell supernatant to the quantity of radioactivity in the control;    wherein said assay is performed using the binding assay kit of  claim 61 .    
     
     
         77 . A competitive binding assay for assessing affinity of a test antibody to a target cell, comprising 
 (i) preparing a ruthenium-labeled control antibody;    (ii) incubating increasing amounts of test antibody and increasing amounts of unlabeled control antibody with a fixed concentration of fixed, fresh or lyophilized antigen-positive cells and a trace amount of ruthenium-labeled antibody wherein each separate concentration of test antibody and each separate concentration of control antibody are in separate tubes, respectively;    (iii) determining the quantity of binding in each reaction tube based on relative electrochemiluminescence (ECL) using ORIGEN instrumentation; and    (iv) calculating the average affinity value of the test antibody.    
     
     
         78 . The competitive binding assay of  claim 77  wherein the control and test antibodies are anti-CD20 antibodies.  
     
     
         79 . A competitive binding assay of  claim 77  wherein the antigen-positive cells as CD20-positive.  
     
     
         80 . The competitive binding assay of  claim 79  wherein the antigen-positive cells are SB cells (ATCC # CCL 120).  
     
     
         81 . The radiolabeling kit of  claim 1  further comprising a vial of chimeric anti-CD20 antibody to be administered in a combined therapeutic regimen prior to or subsequent to the radiolabeled antibody.  
     
     
         82 . The binding assay and radiolabeling kit of  claim 52 , further comprising a vial of chimeric anti-CD20 antibody to be administered in a combined therapeutic regimen prior to or subsequent to the radiolabeled antibody.