Antibodies against claudin 18.2 useful in cancer diagnosis
The invention relates to antibodies directed against an epitope located within the C-terminal portion of CLDN18.2 which are useful, for example, in diagnosing cancer and/or in determining whether cancer cells express CLDN18.2.
1. An antibody or antigen binding fragment thereof that binds to claudin 18.2 (CLDN18.2) or a peptide having the amino acid sequence TEDEVQSYPSKHDYV (SEQ ID NO: 5) or EVQSYPSKHDYV (SEQ ID NO: 6)
wherein the antibody or antigen-binding fragment comprises
(i) an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 8,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 9, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 10; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 12,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 13, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 14; or
(ii) an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 16,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 17, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 18; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 20,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 21, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 22.
2. The antibody or antigen-binding fragment thereof of claim 1 , wherein said CLDN18.2 is cell surface membrane-bound CLDN18.2.
3. The antibody or antigen-binding fragment thereof of claim 1 , wherein said CLDN18.2 is present on cancer cells.
4. The antibody or antigen-binding fragment thereof of claim 3 , wherein said cancer cells are CLDN18.2 expressing cancer cells.
5. The antibody or antigen-binding fragment thereof of claim 3 , wherein said cancer cells are selected from the group consisting of gastric, esophageal, pancreatic, lung, ovarian, colon, hepatic, head-neck, and gallbladder cancer cells.
6. The antibody or antigen-binding fragment thereof of claim 1 , wherein the antibody or antigen-binding fragment thereof does not bind to non-cancerous cells except stomach epithelial cells.
7. The antibody or antigen-binding fragment thereof of claim 1 , wherein the antibody or antigen-binding fragment thereof does not bind to non-cancerous lung cells.
8. The antibody of claim 1 , wherein the antibody is a chimeric, human or humanized antibody.
9. The antibody of claim 1 , wherein the antibody is a monoclonal antibody.
10. A conjugate comprising an antibody or antigen-binding fragment of claim 1 coupled to at least one detectable label.
11. A hybridoma capable of producing the antibody of claim 1 .
12. The antibody or antigen-binding fragment of claim 1 , wherein said CLDN18.2 comprises the amino acid sequence according to SEQ ID NO: 2 of the sequence listing or a variant of said amino acid sequence.
13. The antibody or antigen-binding fragment of claim 1 , wherein the antibody or antigen-binding fragment comprises
an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 16,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 17, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 18; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 20,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 21, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 22.
14. The antibody or antigen-binding fragment of claim 1 , wherein the antibody or antigen-binding fragment comprises
an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 8,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 9, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 10; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 12,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 13, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 14.
15. The antibody or antigen-binding fragment of claim 13 , wherein the antibody or antigen-binding fragment comprises an antibody heavy chain comprising the amino acid sequence set forth in SEQ ID NO: 15, and an antibody light chain comprising the amino acid sequence set forth in SEQ ID NO: 19.
16. The antibody or antigen-binding fragment of claim 14 , wherein the antibody or antigen-binding fragment comprises an antibody heavy chain comprising the amino acid sequence set forth in SEQ ID NO: 7, and an antibody light chain comprising the amino acid sequence set forth in SEQ ID NO: 11.
17. A diagnostic test kit which comprises the antibody or antigen-binding fragment of claim 1 .
18. A method for detecting CLDN18.2 or determining the quantity of CLDN18.2 in a sample comprising the steps of:
(i) contacting a sample with the antibody or antigen-binding fragment of claim 1 and
(ii) detecting the formation of a complex or determining the quantity of a complex between the antibody or the antigen-binding fragment and CLDN18.2.
19. A method for determining whether cells express CLDN18.2 comprising the steps of:
(i) contacting a cellular sample with the antibody or antigen-binding fragment of claim 1 and
(ii) detecting the formation of a complex between the antibody or the antigen-binding fragment and CLDN18.2 expressed by cells in said sample.
20. A method for diagnosis, detection or monitoring of cancer comprising the steps of:
contacting a biological sample with the antibody or antigen-binding fragment of claim 1 and
(ii) detecting the formation of a complex and/or determining the quantity of a complex between the antibody or the antigen-binding fragment and CLDN18.2.
21. A method for determining whether a cancer is treatable by a cancer therapy targeting CLDN18.2 comprising the steps of:
(i) contacting a sample comprising cancer cells with the antibody or antigen-binding fragment of claim 1 and
(ii) detecting the formation of a complex between the antibody or the antigen-binding fragment and CLDN18.2.
22. The method of claim 18 , wherein the sample comprises a paraffin embedded tissue section fixed with paraformaldehyde.
23. The method of claim 18 , wherein, in step (i), the antibody or antigen binding fragment is at a concentration of about 0.1 to about 0.5 μg/ml.
24. The method of claim 23 , wherein the concentration is about 0.2 μg/ml.
25. The method of claim 18 , wherein step (i) comprises incubating the sample with the antibody or antigen-binding fragment overnight at 4° C.
26. The method of claim 18 , wherein the antibody or antigen binding fragment is labeled with a detectable label.
27. The method of claim 26 , wherein the detectable label is an enzyme or a fluorophore.
28. The method of claim 18 , wherein the method further comprises contacting the antibody or antigen-binding fragment with a secondary antibody, wherein the secondary antibody is labeled with a detectable label.
29. The method of claim 28 , wherein the secondary antibody is a horseradish-peroxidase (HRP)-labeled secondary antibody.
30. The method of claim 29 , wherein step (ii) comprises exposing the HRP-labeled secondary antibody to a chemiluminescent substrate.
31. The method of claim 18 , wherein the antibody or antigen-binding fragment comprises
an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 8,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 9, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 10; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 12,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 13, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 14.
32. The method of claim 18 , wherein the antibody or antigen-binding fragment comprises an antibody heavy chain comprising the amino acid sequence set forth in SEQ ID NO: 7, and an antibody light chain comprising the amino acid sequence set forth in SEQ ID NO: 11.
33. The method of claim 18 , wherein the antibody or antigen-binding fragment comprises
an antibody heavy chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 16,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 17, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 18; and
an antibody light chain comprising:
a CDR1 having the amino acid sequence set forth in SEQ ID NO: 20,
a CDR2 having the amino acid sequence set forth in SEQ ID NO: 21, and
a CDR3 having the amino acid sequence set forth in SEQ ID NO: 22.
34. The method of claim 18 , wherein the antibody or antigen-binding fragment comprises an antibody heavy chain comprising the amino acid sequence set forth in SEQ ID NO: 15, and an antibody light chain comprising the amino acid sequence set forth in SEQ ID NO: 19.