1,2,4-oxadiazole derivatives as immunomodulators

1. A method of treating cancer in a subject in need thereof, comprising administering to the subject a compound of formula (I) or a pharmaceutically acceptable salt or a pharmaceutically acceptable composition thereof:

wherein,

Q is S or O;

R 1 represents a side chain of an amino acid residue Ser or Thr, optionally substituted with alkyl or acyl;

R 2 is hydrogen or —CO-Aaa;

Aaa is an amino acid residue Thr or Ser; wherein a C-terminus thereof is a free terminus, is amidated, or is esterified;

R 3 represents a side chain of an amino acid residue Asn, Asp, Gln, or Glu;

----- is an optional bond;

R 4 and R 5 independently are hydrogen or absent; and

R 6 is hydrogen, alkyl, or acyl.

2. The method according to claim 1 , wherein Q is O.

3. The method according to claim 1 , wherein R 6 is H.

4. The method according to claim 1 , wherein R 6 is —C(O)CH 3 , —C(O)CH 2 CH 3 , —C(O)(CH 2 ) 2 CH 3 , —C(O)(CH 2 ) 3 CH 3 , —C(O)(CH 2 ) 4 CH 3 , or —C(O)(CH 2 ) 5 CH 3 .

5. The method according to claim 1 , wherein R 2 is —CO-Aaa.

6. The method according to claim 1 , wherein the compound of formula (I) is a compound of formula (IA):

or a pharmaceutically acceptable salt thereof; wherein,

R 1 represents a side chain of an amino acid residue Ser or Thr, optionally substituted with alkyl or acyl;

R 3 represents a side chain of an amino acid residue Asn, Asp, Gln, or Glu; and

Aaa is an amino acid residue Thr or Ser; wherein the C-terminus thereof is a free terminus, is amidated, or is esterified.

7. The method according to claim 1 , wherein Aaa is the amino acid residue Thr or Ser; wherein the C-terminus is the free terminus.

8. The method according to claim 1 , wherein the compound of formula (I) is a compound of formula (IB):

or a pharmaceutically acceptable salt thereof; wherein,

R 1 represents a side chain of an amino acid residue Ser or Thr, optionally substituted with alkyl or acyl; and

R 3 represents a side chain of an amino acid residue Asn, Asp, Gln, or Glu.

9. The method according to claim 1 , wherein R 1 represents the side chain of an amino acid residue Ser or Thr.

10. The method according to claim 1 , wherein R 1 is substituted with C 1-5 alkyl.

11. The method according to claim 1 , wherein R 3 represents the side chain of the amino acid residue Asn or Glu.

12. The method according to claim 1 , wherein:

R 1 represents the side chain of an amino acid residue Ser or Thr;

R 2 is —CO-Aaa;

Aaa is the amino acid residue Thr or Ser; wherein the C-terminus is a free terminus; and

R 3 represents the side chain of the amino acid residue Asn or Glu.

13. The method according to claim 1 , wherein R 1 represents the side chain of the amino acid residue Ser.

14. The method according to claim 1 , wherein R 1 represents the side chain of the amino acid residue Thr.

15. The method according to claim 1 , wherein Aaa is Ser.

16. The method according to claim 1 , wherein Aaa is Thr.

17. The method according to claim 1 , wherein R 3 represents the side chain of the amino acid residue Asn.

18. The method according to claim 1 , wherein R 3 represents the side chain of the amino acid residue Asp.

19. The method according to claim 1 , wherein R 3 represents the side chain of the amino acid residue Gln.

20. The method according to claim 1 , wherein R 3 represents the side chain of the amino acid residue Glu.

21. The method according to claim 1 , wherein R 2 is H.

22. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

23. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

24. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

25. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

26. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

27. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

28. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

29. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

30. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

31. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

32. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

33. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

34. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

35. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

36. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

37. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

38. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

39. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

40. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

41. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

42. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

43. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

44. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

45. The method according to claim 1 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

46. The method according to claim 15 , wherein the compound has the following structure:

or a pharmaceutically acceptable salt thereof.

47. The method according to claim 1 , wherein the cancer is selected from the group consisting of breast cancer, colon cancer, lung cancer, melanoma, prostate cancer, and renal cancer.

48. The method according to claim 47 , wherein the cancer is bone cancer, cancer of the head or neck, pancreatic cancer, skin cancer, cutaneous or intraocular malignant melanoma, carcinoma of the endometrium, carcinoma of the cervix, carcinoma of the vagina, carcinoma of the vulva, Hodgkin's Disease, non-Hodgkin's lymphoma, cancer of the esophagus, cancer of the small intestine, cancer of the endocrine system, cancer of the thyroid gland, cancer of the parathyroid gland, cancer of the adrenal gland, sarcoma of soft tissue, cancer of the urethra, cancer of the penis, chronic or acute leukemias including acute myeloid leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia, solid tumors of childhood, lymphocytic lymphoma, cancer of the bladder, cancer of the kidney or ureter, carcinoma of the renal pelvis, neoplasm of the central nervous system (CNS), primary CNS lymphoma, tumor angiogenesis, spinal axis tumor, brain stem glioma, pituitary adenoma, Kaposi's sarcoma, epidermoid cancer, squamous cell cancer, T-cell lymphoma, environmentally induced cancers, and combinations of said cancers.