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US-20260125688-A1 - Therapeutic Compounds for Red Blood Cell-Mediated Delivery of an Active Pharmaceutical Ingredient to a Target Cell

US20260125688A1US 20260125688 A1US20260125688 A1US 20260125688A1US-20260125688-A1

Abstract

Therapeutic compounds for red blood cell-mediated delivery of an active pharmaceutical ingredient to a target cell are described. The therapeutic compounds are configured to bind CD47 on the surface of a red blood cell and to be subsequently transferred to CD47 on the surface of the target cell, the therapeutic compound ultimately being internalized by the target cell via endocytosis. The target cell may be a cancer cell, a virus-infected cell, or a fibrotic cell.

Inventors

  • HoWon J. Kim
  • In-San Kim
  • Jay S. Kim
  • Sun Hwa Kim
  • Ick Chan Kwon
  • Jong Won Lee
  • Yoo Soo YANG
  • Hong Yeol Yoon

Assignees

  • KIST (KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY)
  • K2B THERAPEUTICS, INC.

Dates

Publication Date
20260507
Application Date
20251229

Claims (20)

  1. 1 .- 20 . (canceled)
  2. 21 . A therapeutic compound for red blood cell-mediated (RBC-mediated) delivery in a mammalian subject to a target cell expressing CD47, the therapeutic compound comprising: a CD47-binding protein conjugated to an active pharmaceutical ingredient (API) so as to form a conjugate; wherein the CD47-binding protein is selected from the group consisting of vSIRPα (SEQ ID NO: 3), wild type thrombospondin-1 (TSP-1) (SEQ ID NO: 7), ALX148 (SEQ ID NO: 962), TTI-661 (SEQ ID NO: 963), TTI-662 (SEQ ID NO: 964), a homolog of any of the foregoing, and combinations thereof, and is configured to bind the conjugate to CD47 of a red blood cell of the subject so as to enable transport of the conjugate, through the subject's circulatory system, to the target cell, so that (i) the CD47-binding protein, being configured to bind the conjugate to the CD47 of the red blood cell, binds the CD47 of the target cell, thus transferring the conjugate from the red blood cell to the target cell so as to form a conjugate-CD47 complex on the target cell, thereby blocking CD47 and inhibiting CD47 activity as an immune escape mechanism of the target cell, and (ii) the conjugate is taken up by the target cell via endocytosis of the conjugate-CD47 complex, thereby further inhibiting the immune escape mechanism of the target cell and delivering the API into the target cell.
  3. 22 . The therapeutic compound according to claim 1 , wherein the CD47-binding protein is conjugated to the API by a linker.
  4. 23 . The therapeutic compound according to claim 2 , wherein the linker is cleavable.
  5. 24 . The therapeutic compound according to claim 3 , wherein the linker is configured to be cleaved by a lysosomal degradative enzyme.
  6. 25 . The therapeutic compound according to claim 1 , wherein the target cell is a cancer cell.
  7. 26 . The therapeutic compound according to claim 5 , wherein the API is siRNA, the siRNA being a double-stranded RNA molecule including an antisense RNA strand and a sense RNA strand, wherein: (a) the antisense RNA strand is 19-29 nucleotides in length and is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 22-747 and 771-824, (b) the sense RNA strand is 19-29 nucleotides in length and is complementary to 14-29 nucleotides from the antisense RNA strand, and (c) the double stranded RNA molecule has a double stranded region of 14-29 nucleotides in length and a 3′ overhang region of 0-5 nucleotides in length.
  8. 27 . The therapeutic compound according to claim 5 , wherein the API is siRNA, the siRNA being a double-stranded RNA molecule including an antisense RNA strand and a sense RNA strand, wherein: (a) the antisense RNA strand is 19-29 nucleotides in length and is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 22-37, (b) the sense RNA strand is 19-29 nucleotides in length and is complementary to 14-29 nucleotides from the antisense RNA strand, and (c) the double stranded RNA molecule has a double stranded region of 14-29 nucleotides in length and a 3′ overhang region of 0-5 nucleotides in length.
  9. 28 . The therapeutic compound according to claim 5 , wherein the API is siRNA, the siRNA being a double-stranded RNA molecule including an antisense RNA strand and a sense RNA strand, wherein: (a) the antisense RNA strand is 19-29 nucleotides in length and is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 38-39, (b) the sense RNA strand is 19-29 nucleotides in length and is complementary to 14-29 nucleotides from the antisense RNA strand, and (c) the double stranded RNA molecule has a double stranded region of 14-29 nucleotides in length and a 3′ overhang region of 0-5 nucleotides in length.
  10. 29 . The therapeutic compound according to claim 5 , wherein the API is siRNA, the siRNA being a double-stranded RNA molecule including an antisense RNA strand and a sense RNA strand, wherein: (a) the antisense RNA strand is 19-29 nucleotides in length and is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 40-43, (b) the sense RNA strand is 19-29 nucleotides in length and is complementary to 14-29 nucleotides from the antisense RNA strand, and (c) the double stranded RNA molecule has a double stranded region of 14-29 nucleotides in length and a 3′ overhang region of 0-5 nucleotides in length.
  11. 30 . The therapeutic compound according to claim 5 , wherein the API is siRNA, the siRNA being a double-stranded RNA molecule including an antisense RNA strand and a sense RNA strand, wherein: (a) the antisense RNA strand is 19-29 nucleotides in length and is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 44-51, (b) the sense RNA strand is 19-29 nucleotides in length and is complementary to 14-29 nucleotides from the antisense RNA strand, and (c) the double stranded RNA molecule has a double stranded region of 14-29 nucleotides in length and a 3′ overhang region of 0-5 nucleotides in length.
  12. 31 . The therapeutic compound according to claim 5 , wherein the API is shRNA, the shRNA being a single-stranded RNA molecule of 44-71 nucleotides in length, and having, in a 5′ to 3′ direction: a first region of 19-29 nucleotides at the 5′ end of the single-stranded RNA molecule, the first region having a first sequence; a second region of 4-11 nucleotides directly adjacent to the first region, the second region having a second sequence; a third region of 19-29 nucleotides directly adjacent to the second region, the third region having a third sequence; and a fourth region of 2 nucleotides at the 3′ end of the single-stranded RNA molecule, directly adjacent to the third region, the fourth region having a fourth sequence, wherein: (a) the first region has the same number of nucleotides as the third region, (b) the third sequence is the reverse-complement of the first sequence, (c) the third region is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 8-747 and 771-824, and (d) the single-stranded RNA molecule is configured to form a stem loop structure, the first region base pairing with the third region to form a stem, the second region forming a loop, and the fourth region forming a 3′ overhang.
  13. 32 . The therapeutic compound according to claim 5 , wherein the API is shRNA, the shRNA being a single-stranded RNA molecule of 44-71 nucleotides in length, and having, in a 5′ to 3′ direction: a first region of 19-29 nucleotides at the 5′ end of the single-stranded RNA molecule, the first region having a first sequence; a second region of 4-11 nucleotides directly adjacent to the first region, the second region having a second sequence; a third region of 19-29 nucleotides directly adjacent to the second region, the third region having a third sequence; and a fourth region of 2 nucleotides at the 3′ end of the single-stranded RNA molecule, directly adjacent to the third region, the fourth region having a fourth sequence, wherein: (a) the first region has the same number of nucleotides as the third region, (b) the third sequence is the reverse-complement of the first sequence, (c) the third region is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 22-37, and (d) the single-stranded RNA molecule is configured to form a stem loop structure, the first region base pairing with the third region to form a stem, the second region forming a loop, and the fourth region forming a 3′ overhang.
  14. 33 . The therapeutic compound according to claim 5 , wherein the API is shRNA, the shRNA being a single-stranded RNA molecule of 44-71 nucleotides in length, and having, in a 5′ to 3′ direction: a first region of 19-29 nucleotides at the 5′ end of the single-stranded RNA molecule, the first region having a first sequence; a second region of 4-11 nucleotides directly adjacent to the first region, the second region having a second sequence; a third region of 19-29 nucleotides directly adjacent to the second region, the third region having a third sequence; and a fourth region of 2 nucleotides at the 3′ end of the single-stranded RNA molecule, directly adjacent to the third region, the fourth region having a fourth sequence, wherein: (a) the first region has the same number of nucleotides as the third region, (b) the third sequence is the reverse-complement of the first sequence, (c) the third region is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 38-39, and (d) the single-stranded RNA molecule is configured to form a stem loop structure, the first region base pairing with the third region to form a stem, the second region forming a loop, and the fourth region forming a 3′ overhang.
  15. 34 . The therapeutic compound according to claim 5 , wherein the API is shRNA, the shRNA being a single-stranded RNA molecule of 44-71 nucleotides in length, and having, in a 5′ to 3′ direction: a first region of 19-29 nucleotides at the 5′ end of the single-stranded RNA molecule, the first region having a first sequence; a second region of 4-11 nucleotides directly adjacent to the first region, the second region having a second sequence; a third region of 19-29 nucleotides directly adjacent to the second region, the third region having a third sequence; and a fourth region of 2 nucleotides at the 3′ end of the single-stranded RNA molecule, directly adjacent to the third region, the fourth region having a fourth sequence, wherein: (a) the first region has the same number of nucleotides as the third region, (b) the third sequence is the reverse-complement of the first sequence, (c) the third region is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 40-43, and (d) the single-stranded RNA molecule is configured to form a stem loop structure, the first region base pairing with the third region to form a stem, the second region forming a loop, and the fourth region forming a 3′ overhang.
  16. 35 . The therapeutic compound according to claim 5 , wherein the API is shRNA, the shRNA being a single-stranded RNA molecule of 44-71 nucleotides in length, and having, in a 5′ to 3′ direction: a first region of 19-29 nucleotides at the 5′ end of the single-stranded RNA molecule, the first region having a first sequence; a second region of 4-11 nucleotides directly adjacent to the first region, the second region having a second sequence; a third region of 19-29 nucleotides directly adjacent to the second region, the third region having a third sequence; and a fourth region of 2 nucleotides at the 3′ end of the single-stranded RNA molecule, directly adjacent to the third region, the fourth region having a fourth sequence, wherein: (a) the first region has the same number of nucleotides as the third region, (b) the third sequence is the reverse-complement of the first sequence, (c) the third region is complementary to contiguous nucleotides in a target mammalian mRNA sequence, the mRNA sequence being selected from the group consisting of SEQ ID NO: 44-51, and (d) the single-stranded RNA molecule is configured to form a stem loop structure, the first region base pairing with the third region to form a stem, the second region forming a loop, and the fourth region forming a 3′ overhang.
  17. 36 . The therapeutic compound according to claim 5 , wherein the API is an miRNA selected from the group consisting of SEQ ID NO: 825-844, 849-851, 853, 855, 857, 864, 865, and 867-883.
  18. 37 . The therapeutic compound according to claim 5 , wherein the API is an antimiR, the antimiR being a single-stranded nucleic acid molecule of 12-25 nucleotides in length, the antimiR having a sequence of 12-25 contiguous nucleotides that is complementary to contiguous nucleotides in a target mature miRNA product sequence, the mature miRNA product sequence being selected from the group consisting of SEQ ID NO: 884-908, wherein the contiguous nucleotides in the mature miRNA product sequence includes, in a 5′ to 3′ direction, nucleotides 2 to 8 of the mature miRNA product sequence.
  19. 38 . The therapeutic compound according to claim 5 , wherein the API is a small molecule selected from the group consisting of methotrexate; doxorubicin; vinca alkaloids; camptothecin analogues; microtubule-disrupting agents; and DNA-damaging agents.
  20. 39 . The therapeutic compound according to claim 5 , wherein the API is a protein, the protein having an amino acid sequence selected from the group consisting of SEQ ID NO: 909-929 and homologs thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/057,050, filed Nov. 18, 2022, which claims priority from U.S. Provisional Application No. 63/281,370, filed Nov. 19, 2021, and U.S. Provisional Application No. 63/392,323, filed Jul. 26, 2022, each of which is incorporated herein by reference in its entirety. SEQUENCE LISTING This application contains a Sequence Listing that has been submitted electronically as an XML file named “61034-0002007_SL_ST26.XML.” The XML file, created on Dec. 29, 2025, is 4,563,078 bytes in size. The material in the XML file is hereby incorporated by reference in its entirety. TECHNICAL FIELD The present invention relates generally to a therapeutic compound configured to bind CD47, and more particularly to such a compound configured to bind CD47 on the surface of a red blood cell and to be subsequently transferred to CD47 on the surface of a target cell, the therapeutic compound ultimately being internalized by the target cell via endocytosis. BACKGROUND ART Cluster of differentiation 47 (“CD47”), an integrin-associated protein, is a multi-spanning plasma membrane protein involved in the processes inhibiting clearance by phagocytes or neutrophil motility. Signal-regulatory protein alpha (“SIRPα”), a transmembrane protein expressed by innate immune cells such as macrophages and dendritic cells, is the main receptor of CD47. The binding of SIRPα to CD47 triggers SIRPα inhibitory signals, which act as “don't eat me” signals to recipient macrophages, preventing their phagocytic activation. Thus, the SIRPα-CD47 interaction functions as a negative checkpoint for innate and subsequent adaptive immunity. Other proteins, such as signal regulatory protein gamma (“SIRPγ”) and thrombospondin-1 (“TSP-1”) can also bind CD47, thereby inhibiting aspects of immune response. Mammalian cells typically express low levels of CD47 to protect them from phagocytosis. However, cancer cells overexpress CD47 as an evasion mechanism to escape immune surveillance and attack by phagocytic cells. Several human solid tumors overexpress CD47, i.e., the cells of these solid tumors express more CD47 than normal cells on average (Willingham et al. PNAS 109(17):6662-6667 (2012), which is hereby incorporated by reference herein in its entirety). CD47 has thus emerged as a promising new therapeutic target for cancer immunotherapy (Willingham et al. PNAS 109(17):6662-6667 (2012); Weiskopf, Eur. J Cancer 76:100-109 (2017); Weiskopf et al. J Clin Invest 126(7):2610-2620 (2016), each of which is hereby incorporated by reference herein in its entirety). In addition, virus-infected cells also express high levels of CD47. These virus-infected cells include cells infected with SARS-CoV-2, the virus that causes COVID-19 (Cham et al. Cell Rep 14; 31(2):107494 (2020) doi:10.1016/j.celrep.2020.03.058 and McLaughlin et al. bioRxiv 2021.03.01.433404 (2021) doi:10.1101/2021.03.01.433404, each of which is hereby incorporated by reference herein in its entirety). Blockade of CD47 inhibitory signaling has been demonstrated to enhance innate and adaptive immune responses to viral infection. Moreover, increased CD47 expression has been observed in fibrotic fibroblasts and blocking CD47 reverses fibrosis by increasing phagocytosis of profibrotic fibroblasts and by eliminating suppressive effects on adaptive immunity (Cui et al. Nat Commun 11:2795 (2020); Wernig et al. PNAS 2017; 114(18):4757-62; Boyd J Cyst Fibros Suppl 1:S54-S59 (2020); Lerbs et al. JCI Insight 2020; 5(16):e140458 (2020), each of which is hereby incorporated by reference herein in its entirety). CD47, therefore, offers a promising target for the treatment of cancers, viral infections, as well as fibrotic diseases, such as cystic fibrosis. SUMMARY OF THE EMBODIMENTS In accordance with one embodiment of the invention, a therapeutic compound for RBC-mediated delivery in a mammalian subject to a target cell expressing CD47, the therapeutic compound comprising: a CD47-binding protein conjugated to an active pharmaceutical ingredient (“API”) so as to form a conjugate; wherein the CD47-binding protein is selected from the group consisting of wild type SIRPα (SEQ ID NO: 1), vSIRPα (SEQ ID NO: 3), wild type thrombospondin-1 (TSP-1) (SEQ ID NO: 7), wild type SIRPγ (SEQ ID NO: 4), vSIRPγ-1 (SEQ ID NO: 5), vSIRPγ-2 (SEQ ID NO: 6), ALX148 (SEQ ID NO: 962), TTI-661 (SEQ ID NO: 963), TTI-662 (SEQ ID NO: 964), a homolog of any of the foregoing, and combinations thereof, and is configured to bind the conjugate to CD47 of a red blood cell of the subject so as to enable transport of the conjugate, through the subject's circulatory system, to the target cell, so that (i) the CD47-binding protein, being configured to bind the conjugate to the CD47 of the red blood cell, binds the CD47 of the target cell, thus transferring the conjugate from the red blood cell to the target cell so as to form a conjugate-CD47 complex on the target