{
  "abstract": "Background Tumor immune evasion is mediated by multiple redundant pathways, including PD-1/PD-L1-mediated T-cell inhibition, 1 CD47/SIRPα signaling that suppresses macrophage phagocytosis,2 and TGF-β-driven immunosuppression within the tumor microenvironment (TME).3 To overcome these evasion mechanisms, we developed HCB301, a tri-specific IgG4 Fc fusion protein that concurrently blocks PD-L1, CD47, and TGF-β signaling to restore effective anti-tumor immunity.Methods HCB301 was engineered with three functional domains: (1) an anti-PD-L1 antibody for tumor-directed checkpoint blockade, (2) a high-affinity SIRPα variant to disrupt CD47-mediated ‘don’t eat me’ signaling, and (3) a mutant TGF-βRII domain to trap TGF-β ligands. Its functions were evaluated through in vitro bioassays measuring TGFβ-induced Smad2 signaling, PD-1/PD-L1 blockade, and phagocytosis of cancer cells by human monocyte-derived macrophages (MDMs). In vivo efficacy was evaluated using NPG™ mice bearing FaDu (HNSCC)/human PBMC co-mixed xenografts, as well as hPD1/hPDL1/hCD47/hSIRPα transgenic BALB/c mice bearing 4T1-hPDL1/hCD47 tumors.Results HCB301 effectively blocked PD-L1 signaling at a level comparable to atezolizumab and suppressed TGF-β1 activity more potently than M7824, a clinically studied bifunctional fusion protein targeting PD-L1 and TGFβ. 4 Importantly, HCB301 induced robust phagocytosis of PD-L1-high, CD47-positive cancer cells by human MDMs while showing no off-target phagocytosis of red blood cells. This contrasts with magrolimab analogs and suggests a favorable hematologic safety profile, mitigating concerns observed with some CD47-targeting agents.5 In vivo, HCB301 elicited robust anti-tumor activity, equivalent to a triple-agent combination targeting PD-L1, CD47, and TGF-β individually, in both FaDu and 4T1 tumor models.Conclusions HCB301 represents a novel therapeutic approach that simultaneously targets three critical immune evasion pathways through a single tri-specific antibody. By targeting key axes of immune suppression, HCB301 enhances both innate and adaptive anti-tumor responses and may offer therapeutic benefit across a range of solid tumors with high PD-L1 expression, TGF-β activity, or immune-excluded TMEs. Its preclinical efficacy and safety profile support further clinical development as a first-in-class multi-targeted immunotherapeutic. The IND application was approved by both the FDA and NMPA, and Phase I trials were initiated in Q2 2025, offering potential benefits for patients with tumors resistant to current checkpoint inhibitor therapies.References Lin X, Kang K, Chen P, Zeng Z, Li G, Xiong W, Yi M, Xiang B. Regulatory mechanisms of PD-1/PD-L1 in cancers. Mol Cancer. 2024;23(1):108.Jiang C, Sun H, Gong Z, Xu Y, Huang Y, Wang Z. CD47/SIRPα axis: an innate immune checkpoint in tumor immunotherapy. Front Oncol. 2024;14:1378647.Hourani T, Shehade H, Maalouf Y, Al Moustafa AE. CD47/SIRPα axis as a potential biomarker and therapeutic target for cancer immunotherapy. Int Rev Immunol. 2025;44(2):82–97.Strauss J, Heery CR, Schlom J, Madan RA, Cao L, Kang Z, et al. Phase I trial of M7824 (MSB0011359C), a bifunctional fusion protein targeting PD-L1 and TGFβ, in advanced solid tumors. Clin Cancer Res. 2018;24(6):1287–1295.Advani R, Flinn I, Popplewell L, Forero A, Bartlett NL, Ghosh N, et al. CD47 blockade by Hu5F9-G4 and rituximab in non-Hodgkin’s lymphoma. N Engl J Med. 2018;379(18):1711–1721. Let me know if you’d like to generate citations in EndNote or BibTeX format or add more refEthics Approval All in vivo experiments were conducted in compliance with institutional guidelines.",
  "authors": [
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Jiin-Tarng Wang"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Chi-Ling Tseng"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Chieh-Hsin Ho"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Chia-Zhen Wu"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Pet-Tzu Lee"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Hong-Fan Wang"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Pei-Lun Tsai"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Pan-Hsien Kuo"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Ting-Yu Kuo"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Yun-Chih Cheng"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Yi-Jing Chen"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Yi-Hsuan Lu"
    },
    {
      "affiliations": [
        "HanchBio Inc., Taipei, Taiwan"
      ],
      "name": "Wenwu Zhai"
    }
  ],
  "title": "428 HCB301: a novel tri-specific fc fusion protein targeting PD-L1, CD47, and TGFβ remodels the tumor microenvironment and enhance anti-tumor immunity",
  "uid": "f357e927-2c60-5469-bb7d-73efb547c4e7"
}