Radioligands for pretargeted pet imaging and methods of their therapeutic use

Abstract

Described herein are Tz/TCO-based pretargeting strategies using an Al[ 18 F]-NOTA-labeled tetrazine radioligand. This imaging strategy enables delineation of cancer at earlier time points compared to other imaging strategies and further decreases the radiation dose to healthy tissues compared to directly labeled antibodies. Al-based 18 F imaging of small molecules, such as tetrazine, has not been previously achieved due to the decomposition of tetrazine during radiofluorination. Radiofluorination is advantageous over other radiolabeling methods because, in addition to having a shorter half-life, 18 F is more readily available to produce and therefore integrated into hospital workflows.

1 . A composition comprising:
 a tetrazine moiety (Tz);   a radiolabel;   a chelator;   a linker attaching the tetrazine moiety (Tz) to the chelator; and   aluminum or aluminum-containing moiety.   
     
     
         2 . The composition of  claim 1 , wherein the linker is polyethylene glycol (PEG) or (poly)-L-lysine and has a length of from 1 to 100 units and 1 to 200 units, respectively. 
     
     
         3 . The composition of  claim 1 , the composition comprising: 
       
         
           
           
               
               
           
         
       
     
     
         4 . A radioimmunoconjugate comprising:
 (1) a targeting moiety-transcyclooctene (TCO) conjugate; and   (2) a radioligand comprising
 a tetrazine moiety (Tz); 
 a radiolabel; 
 a chelator; 
 a linker attaching the tetrazine moiety (Tz) to the chelator; and 
 aluminum or aluminum-containing moiety. 
   
     
     
         5 . The composition of  claim 1 ,
 wherein the tetrazine moiety (Tz), the chelator, and the linker attaching the tetrazine moiety to the chelator comprises a member selected from the group consisting of: 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23-heptaoxa-2-azapentacosan-25-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23,26,29,32,35-undecaoxa-2-azaheptatriacontan-37-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′-(7-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23,26,29,32,35-undecaoxa-2-azaheptatriacontan-37-yl)thioureido)benzyl)-1,4,7-triazonane-1,4-diyl)diacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-3,7-dioxo-11,14,17,20,23,26,29-heptaoxa-2,8-diazahentriacontan-31-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-3,7-dioxo-11,14,17,20,23,26,29,32,35,38,41-undecaoxa-2,8-diazatritetracontan-43-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(25,28-dioxo-28-((6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)amino)-3,6,9,12,15,18,21-heptaoxa-24-azaoctacosyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(37,40-dioxo-40-((6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)amino)-3,6,9,12,15,18,21,24,27,30,33-undecaoxa-36-azatetracontyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(1-(4-(6-methyl-1,2,4,5-tetrazin-3-yl)phenyl)-3-oxo-6,9,12,15,18,21,24-heptaoxa-2-azaheptacosan-27-amido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(2-(4-(1-(4-(6-methyl-1,2,4,5-tetrazin-3-yl)phenoxy)-3,6,9,12,15,18,21,24,27,30,33-undecaoxahexatriacontan-36-amido)benzyl)-1,4,7-triazonane-1,4,7-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′-(7-(4-(3-(5-amino-6-((4-6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-1,4-diyl)diacetic acid; 2,2′,2″-(3-(4-(3-(5-amino-6-((5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; and 2,2′,2″-(3-(4-(3-(5-amino-6-((5-amino-6-((5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)amino)-6-oxohexyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid.   
     
     
         6 . The composition of  claim 1 , wherein the composition is hydrophilic. 
     
     
         7 . The radioimmunoconjugate of  claim 4 , the radioligand comprising: 
       
         
           
           
               
               
           
         
       
     
     
         8 . The radioimmunoconjugate of  claim 4 , wherein the targeting moiety-TCO conjugate has a TCO moiety comprising: 
       
         
           
           
               
               
           
         
       
     
     
         9 . The radioimmunoconjugate of  claim 4 , wherein the linker is polyethylene glycol (PEG) or (poly)-L-lysine and has a length of from 1 to 100 units and 1 to 200 units, respectively. 
     
     
         10 . A method for synthesizing a radioligand:
 (1) preparing Tz-PEG 11 -NOTA (tetrazine-polyethylene glycol-1,4,7-triazonane-1,4,7-triyl-triacetic acid);   (2) preparing a Al- 18 F complex; and   (3) reacting the Tz-PEG 11 -NOTA and the Al- 18 F complex to yield the radioligand Tz-PEG 11 -Al[ 18 F]-NOTA, wherein the radioligand is obtained in 54% to 65% radiochemical yield (decay-corrected to a start of synthesis) with a purity greater than 96% and specific activities between 20 to 30 Gbq/μmol.   
     
     
         11 . A method for detecting tumor cells, the method comprising:
 (1) administering a quantity of targeting moiety-transcyclooctene (TCO) conjugate to a subject, wherein a portion of the targeting moiety-TCO conjugate localizes at the tumor cells and unbound targeting moiety-TCO conjugate is cleared from blood, from renal system, and/or from the subject after an accumulation interval;   (2) administering a radioligand to the subject after the accumulation interval, wherein the radioligand comprises
 a tetrazine moiety (Tz); 
 a radiolabel; 
 a chelator; 
 a linker attaching the tetrazine moiety (Tz) to the chelator; and 
 aluminum or aluminum-containing moiety, 
   wherein the targeting moiety-TCO conjugate and the radioligand bind together to form a radioimmunoconjugate via an in vivo click reaction at the tumor cells within a region of the subject; and   (3) imaging via positron emission tomography (PET) imaging the radioimmunoconjugate accumulated in the region of the subject within a time period less than 9 hours from the administering of the radioligand.   
     
     
         12 . The method of  claim 11 , wherein the radioligand comprises: 
       
         
           
           
               
               
           
         
       
     
     
         13 . The method of  claim 11 , wherein the targeting moiety-TCO conjugate has a TCO moiety comprising: 
       
         
           
           
               
               
           
         
       
     
     
         14 . The method of  claim 11 , wherein the radioligand has an effective dose of less than 0.1 rem/mCi over a 4 hour accumulation interval. 
     
     
         15 . The method of  claim 11 , wherein the radioligand has a half-life in blood that is less than 100 minutes. 
     
     
         16 . The method of  claim 11 , wherein the radioimmunoconjugate has an activity concentration in a large intestine of the subject that is less than 2% of an initial dose per gram (ID/g) after 2 hour post injection. 
     
     
         17 . The method of  claim 11 , wherein the radioimmunoconjugate has an activity concentration in a gastrointestinal tract of the subject that is less than 2% of an initial dose per gram (ID/g) after 2 hour post injection. 
     
     
         18 . The method of  claim 11 , wherein the radioimmunoconjugate has an activity concentration in a hepatobiliary system of the subject that is less than 2% of an initial dose per gram (ID/g after 2 hour post injection. 
     
     
         19 . The method of  claim 11 , wherein the linker is polyethylene glycol (PEG) or (poly)-L-lysine and has a length of from 1 to 100 units and 1 to 200 units, respectively. 
     
     
         20 . The method of  claim 11 , wherein the radioligand is hydrophilic. 
     
     
         21 . The method of  claim 11 , wherein the targeting moiety is an antibody. 
     
     
         22 . The method of  claim 21 , wherein the antibody is a member selected from the group consisting of trastuzumab, J591, bevacizumab, B43.13, AR9.6, 3F8, 8H9, huA33, and 5B1. 
     
     
         23 . The method of  claim 11 , wherein the targeting moiety is a nanoparticle, a peptide, or other biomolecule. 
     
     
         24 . The method of  claim 11 , wherein the tumor cells are colorectal tumor cells or pancreatic tumor cells. 
     
     
         25 . The method of  claim 11 , wherein the tetrazine moiety (Tz), the chelator, and the linker attaching the tetrazine moiety to the chelator comprises a member selected from the group consisting of: 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23-heptaoxa-2-azapentacosan-25-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23,26,29,32,35-undecaoxa-2-azaheptatriacontan-37-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′-(7-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-1-oxo-5,8,11,14,17,20,23,26,29,32,35-undecaoxa-2-azaheptatriacontan-37-yl)thioureido)benzyl)-1,4,7-triazonane-1,4-diyl)diacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-3,7-dioxo-11,14,17,20,23,26,29-heptaoxa-2,8-diazahentriacontan-31-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(1-(4-(1,2,4,5-tetrazin-3-yl)phenyl)-3,7-dioxo-11,14,17,20,23,26,29,32,35,38,41-undecaoxa-2,8-diazatritetracontan-43-yl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(25,28-dioxo-28-((6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)amino)-3,6,9,12,15,18,21-heptaoxa-24-azaoctacosyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(37,40-dioxo-40-((6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)amino)-3,6,9,12,15,18,21,24,27,30,33-undecaoxa-36-azatetracontyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(3-(4-(1-(4-(6-methyl-1,2,4,5-tetrazin-3-yl)phenyl)-3-oxo-6,9,12,15,18,21,24-heptaoxa-2-azaheptacosan-27-amido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′,2″-(2-(4-(1-(4-(6-methyl-1,2,4,5-tetrazin-3-yl)phenoxy)-3,6,9,12,15,18,21,24,27,30,33-undecaoxahexatriacontan-36-amido)benzyl)-1,4,7-triazonane-1,4,7-triyl)triacetic acid; 2,2′,2″-(3-(4-(3-(5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; 2,2′-(7-(4-(3-(5-amino-6-((4-6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-1,4-diyl)diacetic acid; 2,2′,2″-(3-(4-(3-(5-amino-6-((5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid; and 2,2′,2″-(3-(4-(3-(5-amino-6-((5-amino-6-((5-amino-6-((4-(6-methyl-1,2,4,5-tetrazin-3-yl)benzyl)amino)-6-oxohexyl)amino)-6-oxohexyl)amino)-6-oxohexyl)thioureido)benzyl)-1,4,7-triazonane-2,5,8-triyl)triacetic acid. 
     
     
         26 - 45 . (canceled)