Immunity to X-linked inhibitor of apoptosis protein (XIAP) in malignant melanoma and check-point blockade

Cancer Immunol Immunother. 2019 Aug;68(8):1331-1340. doi: 10.1007/s00262-019-02370-4. Epub 2019 Jul 18.

Abstract

Expression of inhibitors of apoptosis protein (IAP) family members is associated with poor prognosis in cancer patients. Immunity to ML-IAP (livin) and survivin has been well studied in patients with a variety of tumors. XIAP, the most potent inhibitor of apoptosis, is widely expressed in melanoma. To better define its potential role as an immunogenic target, cellular and humoral responses to XIAP were investigated in patients with advanced melanoma. An overlapping peptide library covering the full length of the XIAP protein was used to screen T cell responses of peripheral blood mononuclear cells (PBMC) from stage-IV melanoma patients treated with or without anti-CTLA4 (ipilimumab). The screen identified an array of peptides that predominantly induced CD4+ T cell responses. XIAP epitope-specific CD4+ T cells revealed proliferative responses to melanoma cells that express XIAP. Humoral responses to XIAP were also explored. Cellular and humoral responses to XIAP were associated with beneficial clinical outcomes after ipilimumab-based treatment, supporting XIAP as a potential therapeutic target.

Keywords: CTLA4 blockade; Melanoma; PD-1 blockade; XIAP.

MeSH terms

  • Antineoplastic Agents / therapeutic use*
  • CD4-Positive T-Lymphocytes / immunology*
  • Cell Proliferation
  • Cells, Cultured
  • Enzyme-Linked Immunospot Assay
  • Epitopes, T-Lymphocyte / immunology*
  • Humans
  • Immunity, Humoral
  • Immunotherapy / methods*
  • Ipilimumab / therapeutic use*
  • Lymphocyte Activation
  • Melanoma / drug therapy
  • Melanoma / immunology*
  • Neoplasm Staging
  • Peptide Fragments / immunology*
  • Skin Neoplasms / drug therapy
  • Skin Neoplasms / immunology*
  • Treatment Outcome
  • X-Linked Inhibitor of Apoptosis Protein / immunology*

Substances

  • Antineoplastic Agents
  • Epitopes, T-Lymphocyte
  • Ipilimumab
  • Peptide Fragments
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human