<p>Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) targeting HER2, exhibiting significant clinical efficacy in breast cancer (BC) with varying HER2 expression, including HER2-low and HER2-ultralow. However, the precise mechanism underlying its efficacy and the contribution of immune activation in these settings remain unclear. Here, we demonstrate that T-DXd efficacy in HER2-low and HER2-negative BC is independent of HER2 engagement and ADC internalization. Instead, its activity relies on extracellular proteases, such as cathepsin L (CTSL), within the tumor microenvironment. Irrespective of their HER2 status, tumor and stromal compartments of invasive BC abundantly express CTSL, which efficiently cleaves the specialized linker of T-DXd, facilitating payload release and inducing cytotoxicity against HER2-low/negative tumors. In HER2-positive BC, the antibody backbone of T-DXd engages Fcγ-receptors and drives antibody-dependent cellular phagocytosis (ADCP). Concurrently, its cytotoxic payload (DXd) induces immunogenic cell death, further activating myeloid cells via TLR4 and STING pathways to enhance tumor antigen presentation to CD8+ T cells. Notably, T-DXd cytotoxicity also upregulates tumor CD47 expression, dampening immune activation. Combining T-DXd with CD47 checkpoint blockade significantly enhances anti-tumor immune responses in a HER2-transgenic BC mouse model, while also inducing durable CD8+ T cell memory to prevent tumor recurrence after therapy cessation.</p>

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Effective extracellular payload release and immunomodulatory interactions govern the therapeutic effect of trastuzumab deruxtecan (T-DXd)

  • Li-Chung Tsao,
  • John S. Wang,
  • Xingru Ma,
  • Sirajbir Sodhi,
  • Joey V. Ragusa,
  • Bushangqing Liu,
  • Jason McBane,
  • Tao Wang,
  • Junping Wei,
  • Cong-Xiao Liu,
  • Xiao Yang,
  • Gangjun Lei,
  • Ivan Spasojevic,
  • Ping Fan,
  • Timothy N. Trotter,
  • Michael Morse,
  • Herbert Kim Lyerly,
  • Zachary C. Hartman

摘要

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) targeting HER2, exhibiting significant clinical efficacy in breast cancer (BC) with varying HER2 expression, including HER2-low and HER2-ultralow. However, the precise mechanism underlying its efficacy and the contribution of immune activation in these settings remain unclear. Here, we demonstrate that T-DXd efficacy in HER2-low and HER2-negative BC is independent of HER2 engagement and ADC internalization. Instead, its activity relies on extracellular proteases, such as cathepsin L (CTSL), within the tumor microenvironment. Irrespective of their HER2 status, tumor and stromal compartments of invasive BC abundantly express CTSL, which efficiently cleaves the specialized linker of T-DXd, facilitating payload release and inducing cytotoxicity against HER2-low/negative tumors. In HER2-positive BC, the antibody backbone of T-DXd engages Fcγ-receptors and drives antibody-dependent cellular phagocytosis (ADCP). Concurrently, its cytotoxic payload (DXd) induces immunogenic cell death, further activating myeloid cells via TLR4 and STING pathways to enhance tumor antigen presentation to CD8+ T cells. Notably, T-DXd cytotoxicity also upregulates tumor CD47 expression, dampening immune activation. Combining T-DXd with CD47 checkpoint blockade significantly enhances anti-tumor immune responses in a HER2-transgenic BC mouse model, while also inducing durable CD8+ T cell memory to prevent tumor recurrence after therapy cessation.