Fibroblast activation protein (FAP)-targeted imaging and therapy
The present teachings relate generally to conjugates and methods for imaging a tumor microenvironment in a patient, and to conjugates and methods for imaging cancer-associated fibroblasts (CAFs) in the tumor microenvironment of a patient. The present teachings relate generally to method of making conjugates comprising a fibroblast activation protein (FAP) inhibitor.
1. A conjugate, or a pharmaceutically acceptable salt thereof, having a structure
B-L-X,
wherein B is a fibroblast activation protein (FAP) inhibitor; is of the formula:
wherein each of R 1 and R 2 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl; R 3 is a C 1 -C 4 alkyl, nitrile, or isonitrile;
and each of R 4 , R 5 , and R 6 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl; and n is an integer from 1 to 8
L is a bivalent linker comprising at least one amino acid selected from the group consisting of Glu and Cys, or a derivative thereof; and
X comprises a near infrared (NIR) dye, a radioactive imaging agent, or a therapeutic agent effective against cancer cells and/or cancer-associated fibroblasts (CAF),
wherein the linker further comprises a fragment of the formula
wherein
m is an integer from 0 to 9;
p is an integer from 3 to 10; and
q is an integer from 3 to 100.
2. The conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, wherein B is of the formula
wherein
each of R 1 and R 2 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl;
R 3 is a C 1 -C 4 alkyl, nitrile, or isonitrile; and
each of R 4 , R 5 , and R 6 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl; and
n is an integer from 1 to 8.
3. The conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, wherein the linker comprises a fragment of the formula
wherein
R 6 is H or C 1 -C 6 alkyl;
each of R 7 and R 8 is independently H or C 1 -C 6 alkyl; and
t is an integer from 1 to 8.
4. A conjugate, or a pharmaceutically acceptable salt thereof, having a structure
B-L-X,
wherein B is a fibroblast activation protein (FAP) inhibitor; is of the formula:
wherein each of R 1 and R 2 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl; R 3 is a C 1 -C 4 alkyl, nitrile, or isonitrile;
and each of R 4 , R 5 , and R 6 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl; and n is an integer from 1 to 8
L is a bivalent linker comprising at least one amino acid selected from the group consisting of Glu and Cys, or a derivative thereof; and
wherein X comprises fluorescein maleimide, fluorescein isothiocyanate (FITC), NIR dye S0456, or has a structure selected from the group consisting of
5. The conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, wherein X is a tetrapeptide of the formula
wherein
R 1a , R 3a , R 3a′ and R 3a″ are each independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl and C 3- C 6 cycloalkyl, wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl and C 3- C 6 cycloalkyl is independently optionally substituted by halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, 5- to 7-membered heteroaryl, —OR 13a , —OC(O)R 13a , —OC(O)NR 13a R 13a′ , —OS(O)R 13a , —OS(O) 2 R 13a , —SR 13a , —SC(O)R 13a , —S(O)R 13a , —S(O) 2 R 13a , —S(O) 2 OR 13a , —S(O)NR 13a R 13a′ , —S(O) 2 NR 13a R 13a′ , —OS(O)NR 13a R 13a′ , —OS(O) 2 NR 13a R 13a′ , —NR 13a R 13a′ , —NR 13a C(O)R 14a , —NR 13a C(O)OR 14a , —NR 13a C(O)NR 14a R 14a′ , —NR 13a S(O)R 14a , —NR 13a S(O) 2 R 14a , —NR 13a S(O)NR 13a R 14a′ , —NR 13a S(O) 2 NR 14a R 14a′ , —P(O)(OR 13a ) 2 , —C(O)R 13a , —C(O)OR 13a or —C(O)NR 13a R 13a′ ;
R 2a , R 4a and R 12a are each independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl;
R 5a and R 6a are each independently selected from the group consisting of H, halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, —OR 15a , —SR 15a and —NR 15a R 15a′ , wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl and C 2- C 6 alkynyl is independently optionally substituted by halogen, —OR 16a , —SR 16a , —NR 16a R 16a′ , —C(O)R 16a , —C(O)OR 16a or —C(O)NR 16a R 16a′ ; or R 5a and R 6a taken together with the carbon atom to which they are attached form a —C(O)—;
each R 7a , R 8a , R 9a , R 10a and R 11a is independently selected from the group consisting of H, halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, —CN, —NO 2 , —NCO, —OR 17a , —SR 17a , —S(O) 2 OR 17a , —NR 17a R 17a′ , —P(O)(OR 17a ) 2 , —C(O)R 17a , —C(O)OR 17a and —C(O)NR 17a R 17a′ , wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl and C 2- C 6 alkynyl is independently optionally substituted by halogen, —OR 18a , —SR 18a , —NR 18a R 18a′ , —C(O)R 18a , —C(O)OR 18a or —C(O)NR 18a R 18a′ ;
each R 13a , R 13a′ , R 14a , R 14a′ , R 15a , R 15a′ , R 16a , R 16a′ , R 17a and R 17a′ is independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl and 5- to 7-membered heteroaryl, wherein each hydrogen atom in C 1 -C 7 alkyl, C 2 -C 7 alkenyl, C 2- C 7 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, or 5- to 7-membered heteroaryl is independently optionally substituted by halogen, —OH, —SH, —NH 2 or —CO 2 H;
each R 18a and R 18a′ is independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, 5- to 7-membered heteroaryl —C(O)R 19a , —P(O)(OR 19a ) 2 , and —S(O) 2 OR 19a ,
each R 19a is independently selected from H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl and 5- to 7-membered heteroaryl; and
a is 1, 2 or 3.
6. The conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, wherein B-L comprises a fragment of the formula
7. A conjugate, or a pharmaceutically acceptable salt thereof, having a structure:
B-L-X,
wherein B is of the formula
wherein
each of R 1 and R 2 in independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl;
R 3 is a C 1 -C 4 alkyl, nitrile, or isonitrile;
each of R 4 , R 5 , and R 6 is independently selected from the group consisting of hydrogen, halogen, and C 1 -C 4 alkyl;
n is an integer from 1 to 8;
L is a bivalent linker; and
X comprises a near infrared (NIR) dye, a radioactive imaging agent, or a therapeutic agent effective against cancer cells and/or cancer-associated fibroblasts (CAF).
8. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein B is of the formula
9. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein the linker further comprises a fragment of the formula
wherein
m is an integer from 0 to 9;
p is an integer from 3 to 10; and
q is an integer from 3 to 100.
10. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein the linker comprises a fragment of the formula
wherein
R 6 is H or C 1 -C 6 alkyl;
each of R 7 and R 8 is independently H or C 1 -C 6 alkyl; and
t is an integer from 1 to 8.
11. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein X comprises fluorescein maleimide, fluorescein isothiocyanate (FITC), NIR dye S0456, or has a structure selected from the group consisting of
12. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein X is a tetrapeptide of the formula
wherein
R 1a , R 3a , R 3a′ and R 3a″ are each independently selected from the group consistingof H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl and C 3- C 6 cycloalkyl, wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl and C 3- C 6 cycloalkyl is independently optionally substituted by halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, 5- to 7-membered heteroaryl, —OR 13a , —OC(O)R 13a , —OC(O)NR 13a R 13a′ , —OS(O)R 13a , —OS(O) 2 R 13a , —SR 13a , —SC(O)R 13a , —S(O)R 13a , —S(O) 2 R 13a , —S(O) 2 OR 13a , —S(O)NR 13a R 13a′ , —S(O) 2 NR 13a R 13a′ , —OS(O)NR 13a R 13a′ , —OS(O) 2 NR 13a R 13a′ , —NR 13a R 13a′ , —NR 13a C(O)R 14a , —NR 13a C(O)OR 14a , —NR 13a C(O)NR 14a R 14a′ , —NR 13a S(O)R 14a , —NR 13a S(O) 2 R 14a , —NR 13a S(O)NR 13a R 14a′ , —NR 13a S(O) 2 NR 14a R 14a′ , —P(O)(OR 13a ) 2 , —C(O)R 13a , —C(O)OR 13a or —C(O)NR 13a R 13a′ ;
R 2a , R 4a and R 12a are each independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl;
R 5a and R 6a are each independently selected from the group consisting of H, halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, —OR 15a , —SR 15a and —NR 15a R 15a′ , wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl and C 2- C 6 alkynyl is independently optionally substituted by halogen, —OR 16a , —SR 16a , —NR 16a R 16a′ , —C(O)R 16a , —C(O)OR 16a or —C(O)NR 16a R 16a′ ; or R 5a and R 6a taken together with the carbon atom to which they are attached form a —C(O)—;
each R 7a , R 8a , R 9a , R 10a and R 11a is independently selected from the group consisting of H, halogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, —CN, —NO 2 , —NCO, —OR 17a , —SR 17a , —S(O) 2 OR 17a , —NR 17a R 17a′ , —P(O)(OR 17a ) 2 , —C(O)R 17a , —C(O)OR 17a and —C(O)NR 17a R 17a′ , wherein each hydrogen atom in C 1 -C 6 alkyl, C 2 -C 6 alkenyl and C 2- C 6 alkynyl is independently optionally substituted by halogen, —OR 18a , —SR 18a , —NR 18a R 18a′ , —C(O)R 18a , —C(O)OR 18a or —C(O)NR 18a R 18a′ ;
each R 13a , R 13a′ , R 14a , R 14a′ , R 15a , R 15a′ , R 16a , R 16a′ , R 17a and R 17a′ is independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl and 5- to 7-membered heteroaryl, wherein each hydrogen atom in C 1 -C 7 alkyl, C 2 -C 7 alkenyl, C 2- C 7 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, or 5- to 7-membered heteroaryl is independently optionally substituted by halogen, —OH, —SH, —NH 2 or —CO 2 H;
each R 18a and R 18a′ is independently selected from the group consisting of H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3- C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, 5- to 7-membered heteroaryl —C(O)R 19a , —P(O)(OR 19a ) 2 , and —S(O) 2 OR 19a ,
each R 19a is independently selected from H, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2- C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl and 5- to 7-membered heteroaryl; and
a is 1, 2 or 3.
13. The conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, wherein B-L comprises a fragment of the formula
14. A pharmaceutical composition comprising a conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, and optionally at least one pharmaceutically acceptable excipient.
15. A method of treating cancer in a subject, comprising administering to the subject an effective amount of a conjugate of claim 1 , or a pharmaceutically acceptable salt thereof.
16. A method of imaging a population of cells in vitro, comprising contacting the cells with a conjugate of claim 1 , to provide labelled cells, and visualizing the labelled cells.
17. A method of imaging a population of cells in vivo, comprising administering to a patient an effective amount of a conjugate of claim 1 , or a pharmaceutically acceptable salt thereof, to provide labelled cells; and visualizing the labelled cells.
18. A pharmaceutical composition comprising a conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, and optionally at least one pharmaceutically acceptable excipient.
19. A method of treating cancer in a subject, comprising administering to the subject an effective amount of a conjugate of claim 7 , or a pharmaceutically acceptable salt thereof.
20. A method of imaging a population of cells in vitro, comprising contacting the cells with a conjugate of claim 7 , to provide labelled cells, and visualizing the labelled cells.
21. A method of imaging a population of cells in vivo, comprising administering to a patient an effective amount of a conjugate of claim 7 , or a pharmaceutically acceptable salt thereof, to provide labelled cells; and visualizing the labelled cells.
22. A method of imaging a population of cells, comprising contacting the cells with a conjugate of claim 4 , to provide labelled cells, and visualizing the labelled cells.