CD4+ T-Helper Type 1 Cytokines and Trastuzumab Facilitate CD8+ T-cell Targeting of HER2/neu–Expressing Cancers

Abstract

Vaccination strategies incorporating the immunodominant HLA-A2-restricted HER2/neu-derived peptide 369-377 (HER2369-377) are increasingly utilized in HER2/neu-expressing cancer patients. The failure of post-vaccination HER2369-377-specific CD8+ T cells to recognize HLA-A2posHER2/neu-expressing cells in vitro, however, has been attributed to impaired MHC class I/HLA-A2 presentation observed in HER2/neu-overexpressing tumors. We reconcile this controversy by demonstrating that HER2369-377 is directly recognized by high functional-avidityHER2369-377-specific CD8+ T cells—either genetically modified to express a novel HER2369-377-TCR or sensitized using HER2369-377-pulsed type 1-polarized dendritic cells (DC1)—on class I-abundant HER2low, but not class I-deficient HER2high, cancer cells. Importantly, a critical cooperation between CD4+ T-helper type-1 (Th1) cytokines IFNγ/TNFα and HER2/neu-targeted antibody trastuzumab is necessary to restore class I expression in HER2high cancers, thereby facilitating recognition and lysis of these cells by HER2369-377-specific CD8+ T cells. Concomitant induction of PD-L1 on HER2/neu-expressing cells by IFNγ/TNF and trastuzumab, however, has minimal impact on DC1-sensitized HER2369-377-CD8+ T cell-mediated cytotoxicity. Although activation of EGFR and HER3 signaling significantly abrogates IFNγ/TNFα and trastuzumab-induced class I restoration, EGFR/HER3 receptor blockade rescues class I expression and ensuing HER2369-377-CD8+ cytotoxicity of HER2/neu-expressing cells. Thus, combinations of CD4+ Th1 immune interventions and multivalent targeting of HER family members may be required for optimal anti-HER2/neuCD8+ T cell-directed immunotherapy.

CD4+ Th1 to the rescue in HER-2+ breast cancer

“…Similarly, only the combination of a monoclonal antibody and IFNg/TNFa rendered the HER2 high cells susceptible to CD8 C mediated recognition and lysis. 6 Consistent with the clinical benefit seen following treatment with dual monoclonal antibodies, trastuzumab and pertuzumab, treatment with IFNg/TNFa and both trastuzumab and pertuzumab increased MHC class-I expression and CD8 C mediated cytotoxicity more than IFNg/TNFa or IFNg/TNFa and either trastuzumab or pertuzumab (Fig. 1).…”

“…Upregulation of PD-L-1 would facilitate the use of PD-1/PD-L-1 inhibition in the treatment of HER2 breast cancer. 6 CD4 C T-cells have long been recognized as a critical aide to the survival and function of CD8 C T-cells; our work has shown that CD4 C T-cells further facilitate CD8 C cytotoxicity by modifying the tumor environment. Unfortunately, we have previously shown that there is an early and progressive loss of anti-HER2 CD4 C Th1 response in breast tumorigenesis-healthy patients have a strong anti-HER2 CD4 C Th1 immune response that is decreased in patients with ductal carcinoma in situ and nearly absent in patients with invasive breast cancer.…”

“…However, dual treatment with IFNg/TNFa was only able to significantly increase anti-HER2 CD8 C mediated recognition and cell lysis in HER2 intermediate cell lines, but not HER2 high cell lines. 6 In contrast, while treatment with monoclonal antibodies alone, trastuzumab, pertuzumab, or both trastuzumab and pertuzumab, had little effect on MHC class-I expression or CD8 C mediated cytotoxicity, the combination of a monoclonal antibody and IFNg/TNFa dramatically increased MHC class-I expression on all HER2 expressing cell lines, and was significantly better than Th1 cytokine treatment (IFNg/TNFa) in HER2 high cell lines. Similarly, only the combination of a monoclonal antibody and IFNg/TNFa rendered the HER2 high cells susceptible to CD8 C mediated recognition and lysis.…”

“…Furthermore, we demonstrated that HER2 369-377 -specific CD8 C T-cells recognize the epitope HER2 369-377 on the HER2 low /MHC class-I expressing tumor cells, but not the stealth HER2 high /MHC class-I deficient tumor cells. 6 We then investigated strategies to restore MHC class-I expression using CD4 C Th1 cytokines, IFNg and TNFa, and HER2 targeted tyrosine kinase inhibitors, trastuzumab and pertuzumab. The CD4 C cytokine, IFNg, has been shown to induce MHC class-I expression in HER2 overexpressing tumors in murine models.…”

Rationale for a Multimodality Strategy to Enhance the Efficacy of Dendritic Cell-Based Cancer Immunotherapy

“…We have recently demonstrated that cooperation between DC1-driven Th1 cytokines IFN-γ/TNF-α and HER2/ neu -targeted antibody trastuzumab is necessary for restoration of MHC class I expression in HER2-overexpressing, but not HER2-low, cancer cells in vitro , thereby facilitating recognition and lysis of these cells by DC1-sensitized HER2-specific CD8 + T-cells. Activation of EGFR and HER3 signaling abrogated IFN-γ/TNF-α and trastuzumab-induced class I restoration; however, concomitant EGFR/HER3 receptor blockade rescued class I expression and ensuing CD8 + T-cell cytotoxicity of HER2/ neu -expressing cells ( 64 ). Therefore, combinations of DC1-directed Th1 immune interventions and multivalent molecular targeting of HER family members may be essential for optimal HER2/ neu -directed immunotherapy.…”