Role of Dendritic Cell Phenotype, Determinant Spreading, and Negative Costimulatory Blockade in Dendritic Cell-Based Melanoma Immunotherapy

Authors:
  • JGJohn A. Glaspy
    John A. Glaspy
  • YLYohan Lee
    Yohan Lee
  • VDVivian B. Dissette
    Vivian B. Dissette
  • ESElisabeth Seja
    Elisabeth Seja
  • HVHuong T. Vu
    Huong T. Vu
  • NTN. Simon Tchekmedyian
    N. Simon Tchekmedyian
  • DODenise Oseguera
    Denise Oseguera
  • BCBegonya Comin-Anduix
    Begonya Comin-Anduix
  • JWJennifer A. Wargo
    Jennifer A. Wargo
  • SASaral N. Amarnani
    Saral N. Amarnani
  • WMWilliam H. McBride
    William H. McBride
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Abstract
MART-127–35-peptide-pulsed immature dendritic cells (DCs) resulted in immunologic and clinical activity in a prior phase 1 trial. A phase 2 cohort expansion was initiated to further characterize the phenotype and cytokine milieu of the DC vaccines and their immunologic activity in vitro and to further examine a possible link between clinical activity and determinant spreading. In an open-label phase 2 trial, 107 autologous ex vivo generated DCs pulsed with the HLA-A*0201 immunodominant peptide MART-127–35 were administered to 10 subjects with stage II–IV melanoma. The experimental vaccines were administered intradermally in a biweekly schedule for a total of three injections, and blood for immunologic assays was obtained before each administration and at three time points after. DC vaccine preparations had wide intra- and interpatient variability in terms of cell surface markers and preferential cytokine milieu, but they did not correlate with the levels of antigen-specific T cells after vaccination. Of four patients with measurable disease, one had stable disease for 6 months and another has a continued complete response for over 2 years, which is confounded by receiving a closely sequenced CTLA4 blocking antibody. The DC vaccines induced determinant spreading in this subject, and CTLA4 blockade reactivated T cells with prior antigen exposure. The DC phenotype and cytokine profile do not correlate with the ability to induce antigen-specific T cells, while determinant spreading after DC immunization may be a marker of an efficient antitumor response. Sequential CTLA4 blockade may enhance the immune activity of DC-based immunotherapy.

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