Therapeutic targeting with DABIL-4 depletes myeloid suppressor cells in 4T1 triple-negative breast cancer model

Mol Oncol. 2021 May;15(5):1330-1344. doi: 10.1002/1878-0261.12938. Epub 2021 Mar 24.


In many solid tumors including triple-negative breast cancer (TNBC), upregulation of the interleukin-4 receptor (IL-4R) has been shown to promote cancer cell proliferation, apoptotic resistance, metastatic potential, and a Th2 response in the tumor microenvironment (TME). Since immunosuppressive cells in the TME and spleen including myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) also express the IL-4R, we hypothesized that selective depletion of IL-4R-bearing cells in TNBC would result in the direct killing of tumor cells and the depletion of immunosuppressive cells and lead to an enhanced antitumor response. To selectively target IL-4R+ cells, we employed DABIL-4, a fusion protein toxin consisting of the catalytic and translocation domains of diphtheria toxin fused to murine IL-4. As anticipated, DABIL-4 has potent cytotoxic activity against TNBC cells both in vitro and in vivo. We demonstrate in the murine 4T1 TNBC model that DABIL-4 significantly reduces tumor growth, splenomegaly, and lung metastases. Importantly, we also show that the administration of DABIL-4 results in the selective depletion of MDSCs, TAMs, and regulatory T cells in treated mice, with a concomitant increase in IFN-γ+ CD8 effector T cells in the TME. Since the 4T1 antitumor activity of DABIL-4 was largely diminished in IL-4R knockout mice, we postulate that DABIL-4 functions primarily as an immunotherapeutic by the depletion of MDSCs, TAMs, and regulatory T cells. NanoString analysis of control and treated tumors confirmed and extended these observations by showing a marked decline of mRNA transcripts that are associated with tumorigenesis and metastasis. In conclusion, we demonstrate that DABIL-4 targeting of both tumor and immunosuppressive host cells likely represents a novel and effective treatment strategy for 4T1 TNBC and warrants further study.

Keywords: DABIL-4; IL-4R; diphtheria fusion toxin; myeloid-derived suppressor cells; triple-negative breast cancer; tumor-associated macrophages.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / drug therapy*
  • Adenocarcinoma / pathology
  • Animals
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Apoptosis / drug effects
  • Cell Count
  • Cell Line, Tumor
  • Female
  • Humans
  • Interleukin-4 / chemistry
  • Interleukin-4 / therapeutic use
  • Interleukin-4 Receptor alpha Subunit / chemistry
  • Interleukin-4 Receptor alpha Subunit / therapeutic use
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Molecular Targeted Therapy
  • Myeloid-Derived Suppressor Cells / drug effects*
  • Myeloid-Derived Suppressor Cells / pathology
  • Recombinant Fusion Proteins / pharmacology
  • Recombinant Fusion Proteins / therapeutic use*
  • Triple Negative Breast Neoplasms / drug therapy*
  • Triple Negative Breast Neoplasms / pathology
  • Xenograft Model Antitumor Assays


  • Antineoplastic Agents
  • IL4R protein, human
  • Interleukin-4 Receptor alpha Subunit
  • Recombinant Fusion Proteins
  • Interleukin-4