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<p>The immune checkpoint CD47 is highly upregulated in several cancers as an innate immune escape mechanism. CD47 delivers a “don’t eat me” signal to its co-receptor signal regulatory protein&#xa0;α (SIRPα), thereby inhibiting phagocytosis. Blocking the CD47–SIRPα axis is a promising immunotherapeutic strategy against cancer. However, early trial data has demonstrated on-target off-leukemia toxicity. In addition, the ubiquitous expression pattern of CD47 might contribute to an antigen sink. In this study, we combined low-affinity CD47 checkpoint blockade and specific tumor targeting in a multivalent and multifunctional antibody construct to prevent CD47-related toxicities. First, we established a local inhibitory checkpoint monoclonal antibody (LicMAb) by fusing two <i>N</i>-terminal extracellular domains of SIRPα to a full-length anti-human mesothelin (MSLN)-IgG1 antibody, a well-described tumor-associated antigen in epithelial ovarian cancer (EOC) and pancreatic ductal adenocarcinoma (PDAC). Next, we evaluated the SIRPα-αMSLN LicMAb for mediating a tumor-restricted immune response as observed by antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP). Our data validates CD47 and MSLN as highly upregulated targets expressed on various solid cancer entities, particularly EOC. We show tumor-specific binding and CD47 blocking by the SIRPα-αMSLN LicMAb even in the presence of healthy CD47-expressing cells. Furthermore, the LicMAb induces NK-cell-mediated cytotoxicity and improves phagocytosis of EOC and PDAC tumor cells. Moreover, cell death in EOC-derived organoids was specifically LicMAb-driven. Hence, the SIRPα-αMSLN LicMAb combines a tumor-restricted blockade of the CD47–SIRPα axis with a specific antitumor response while preventing on-target off-tumor toxicities. Our data supports the multifunctional SIRPα-αMSLN LicMAb as a promising approach to treating solid tumors.</p> Graphical abstract <p></p> <p>The local inhibitory checkpoint monoclonal antibody (LicMAb) binds mesothelin (MSLN) with high affinity and simultaneously blocks CD47 on MSLN-expressing tumor cells to inhibit the “don’t eat me” signal. CD47 is blocked by the fused extracellular SIRPα domain that intrinsically has a low affinity. Furthermore, the SIRPα-αMSLN LicMAb is based on a human IgG1 backbone to provide an Fc receptor (FcR)-activating stimulus to enable direct NK-cell-mediated killing by granzyme B (GrzB) and perforin secretion, and an additional pro-phagocytic signal to phagocytic cells, such as macrophages (MØ). This leads to tumor-restricted antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of cancer cells. This scheme was created with BioRender (BioRender.com/g77u465).</p>

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Targeted CD47 checkpoint blockade using a mesothelin-directed antibody construct for enhanced solid tumor-specific immunotherapy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年5月22日

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  • Anna Reischer,
  • Alexandra Leutbecher,
  • Björn Hiller,
  • Enrico Perini,
  • Kieron White,
  • Alejandra Hernández-Cáceres,
  • Alexandra Schele,
  • Benjamin Tast,
  • Lisa Rohrbacher,
  • Lis Winter,
  • Bastian Czogalla,
  • Sven Mahner,
  • Heinrich Flaswinkel,
  • Heinrich Leonhardt,
  • Lorenza Wyder,
  • Christian Wichmann,
  • Denis Maenner,
  • Fabian Trillsch,
  • Mirjana Kessler,
  • Karl-Peter Hopfner,
  • Nadja C. Fenn,
  • Marion Subklewe

摘要

The immune checkpoint CD47 is highly upregulated in several cancers as an innate immune escape mechanism. CD47 delivers a “don’t eat me” signal to its co-receptor signal regulatory protein α (SIRPα), thereby inhibiting phagocytosis. Blocking the CD47–SIRPα axis is a promising immunotherapeutic strategy against cancer. However, early trial data has demonstrated on-target off-leukemia toxicity. In addition, the ubiquitous expression pattern of CD47 might contribute to an antigen sink. In this study, we combined low-affinity CD47 checkpoint blockade and specific tumor targeting in a multivalent and multifunctional antibody construct to prevent CD47-related toxicities. First, we established a local inhibitory checkpoint monoclonal antibody (LicMAb) by fusing two N-terminal extracellular domains of SIRPα to a full-length anti-human mesothelin (MSLN)-IgG1 antibody, a well-described tumor-associated antigen in epithelial ovarian cancer (EOC) and pancreatic ductal adenocarcinoma (PDAC). Next, we evaluated the SIRPα-αMSLN LicMAb for mediating a tumor-restricted immune response as observed by antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP). Our data validates CD47 and MSLN as highly upregulated targets expressed on various solid cancer entities, particularly EOC. We show tumor-specific binding and CD47 blocking by the SIRPα-αMSLN LicMAb even in the presence of healthy CD47-expressing cells. Furthermore, the LicMAb induces NK-cell-mediated cytotoxicity and improves phagocytosis of EOC and PDAC tumor cells. Moreover, cell death in EOC-derived organoids was specifically LicMAb-driven. Hence, the SIRPα-αMSLN LicMAb combines a tumor-restricted blockade of the CD47–SIRPα axis with a specific antitumor response while preventing on-target off-tumor toxicities. Our data supports the multifunctional SIRPα-αMSLN LicMAb as a promising approach to treating solid tumors.

Graphical abstract

The local inhibitory checkpoint monoclonal antibody (LicMAb) binds mesothelin (MSLN) with high affinity and simultaneously blocks CD47 on MSLN-expressing tumor cells to inhibit the “don’t eat me” signal. CD47 is blocked by the fused extracellular SIRPα domain that intrinsically has a low affinity. Furthermore, the SIRPα-αMSLN LicMAb is based on a human IgG1 backbone to provide an Fc receptor (FcR)-activating stimulus to enable direct NK-cell-mediated killing by granzyme B (GrzB) and perforin secretion, and an additional pro-phagocytic signal to phagocytic cells, such as macrophages (MØ). This leads to tumor-restricted antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) of cancer cells. This scheme was created with BioRender (BioRender.com/g77u465).