Results from a phase I clinical study of the novel Ii-Key/HER-2/neu(776-790) hybrid peptide vaccine in patients with prostate cancer

Clin Cancer Res. 2010 Jul 1;16(13):3495-506. doi: 10.1158/1078-0432.CCR-10-0085. Epub 2010 May 13.


Purpose: Active immunotherapy is emerging as a potential therapeutic approach for prostate cancer. We conducted the first phase I trial of an Ii-Key/HER-2/neu(776-790) hybrid peptide vaccine (AE37) with recombinant granulocyte macrophage colony-stimulating factor as adjuvant in patients with HER-2/neu(+) prostate cancer. The primary end points of the study were to evaluate toxicity and monitor patients' immune responses to the vaccine.

Experimental design: Thirty-two HER-2/neu(+), castrate-sensitive, and castrate-resistant prostate cancer patients were enrolled. Of these, 29 patients completed all six vaccination cycles with AE37. Immunologic responses in the total patient population were monitored by delayed-type hypersensitivity and IFN-gamma ELISPOT and intracellular staining. Regulatory T-cell (Treg) frequency and plasma HER-2/neu and transforming growth factor-beta levels were also determined. Immunologic responses were also analyzed among groups of patients with different clinical characteristics. Local/systemic toxicities were monitored throughout the study.

Results: Toxicities beyond grade 2 were not observed. Seventy-five percent of patients developed augmented immunity to the AE37 vaccine and 65% to the unmodified AE36 peptide as detected in the IFN-gamma-based ELISPOT assay. Intracellular IFN-gamma analyses revealed that AE37 elicited both CD4(+) and CD8(+) T-cell responses. Eighty percent of the patients developed a positive delayed-type hypersensitivity reaction to AE36. Additionally, significant decreases could be detected in circulating Treg frequencies, plasma HER-2/neu, and serum transforming growth factor-beta levels. Patients with less extensive disease developed better immunologic responses on vaccination.

Conclusion: AE37 vaccine is safe and can induce HER-2/neu-specific cellular immune responses in patients with castrate-sensitive and castrate-resistant prostate cancer, thus emphasizing the potential of AE37 to target HER-2/neu for the immunotherapy of prostate cancer.

Publication types

  • Clinical Trial, Phase I
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / therapeutic use
  • Aged
  • Aged, 80 and over
  • Antigens, Differentiation, B-Lymphocyte / immunology*
  • Antigens, Differentiation, T-Lymphocyte / immunology
  • Cancer Vaccines / adverse effects
  • Cancer Vaccines / therapeutic use*
  • Granulocyte-Macrophage Colony-Stimulating Factor / therapeutic use*
  • Histocompatibility Antigens Class II / immunology*
  • Humans
  • Male
  • Middle Aged
  • Peptide Fragments / immunology*
  • Prostatic Neoplasms / immunology
  • Prostatic Neoplasms / therapy*
  • Receptor, ErbB-2 / immunology*
  • Recombinant Proteins
  • Vaccines, Subunit / therapeutic use*


  • AE37 vaccine
  • Adjuvants, Immunologic
  • Antigens, Differentiation, B-Lymphocyte
  • Antigens, Differentiation, T-Lymphocyte
  • Cancer Vaccines
  • HER-2 protein (776-790)
  • Histocompatibility Antigens Class II
  • Peptide Fragments
  • Recombinant Proteins
  • T lymphocyte activation molecule H4
  • Vaccines, Subunit
  • invariant chain
  • Granulocyte-Macrophage Colony-Stimulating Factor
  • Receptor, ErbB-2