Breast Cancer Research (Aug 2018)

Polyfunctional anti-human epidermal growth factor receptor 3 (anti-HER3) antibodies induced by HER3 vaccines have multiple mechanisms of antitumor activity against therapy resistant and triple negative breast cancers

  • Takuya Osada,
  • Zachary C. Hartman,
  • Junping Wei,
  • Gangjun Lei,
  • Amy C. Hobeika,
  • William R. Gwin,
  • Marcio A. Diniz,
  • Neil Spector,
  • Timothy M. Clay,
  • Wei Chen,
  • Michael A. Morse,
  • H. Kim Lyerly

DOI
https://doi.org/10.1186/s13058-018-1023-x
Journal volume & issue
Vol. 20, no. 1
pp. 1 – 14

Abstract

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Abstract Background Upregulation of human epidermal growth factor receptor 3 (HER3) is a major mechanism of acquired resistance to therapies targeting its heterodimerization partners epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), but also exposes HER3 as a target for immune attack. We generated an adenovirus encoding full length human HER3 (Ad-HER3) to serve as a cancer vaccine. Previously we reported the anti-tumor efficacy and function of the T cell response to this vaccine. We now provide a detailed assessment of the antitumor efficacy and functional mechanisms of the HER3 vaccine-induced antibodies (HER3-VIAs) in serum from mice immunized with Ad-HER3. Methods Serum containing HER3-VIA was tested in complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) assays and for its effect on HER3 internalization and degradation, downstream signaling of HER3 heterodimers and growth of metastatic HER2+ (BT474M1), HER2 therapy-resistant (rBT474), and triple negative (MDA-MB-468) breast cancers. Results HER3-VIAs mediated CDC and ADCC, HER3 internalization, interruption of HER3 heterodimer-driven tumor signaling pathways, and anti-proliferative effects against HER2+ tumor cells in vitro and significant antitumor effects against metastatic HER2+ BT474M1, treatment refractory HER2+ rBT474 and triple negative MDA-MB-468 in vivo. Conclusions In addition to the T cell anti-tumor response induced by Ad-HER3, the HER3-VIAs provide additional functions to eliminate tumors in which HER3 signaling mediates aggressive behavior or acquired resistance to HER2-targeted therapy. These data support clinical studies of vaccination against HER3 prior to or concomitantly with other therapies to prevent outgrowth of therapy-resistant HER2+ and triple negative clones.

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