Broad cross-presentation of the hematopoietically derived PR1 antigen on solid tumors leads to susceptibility to PR1-targeted immunotherapy.

PR1 is a HLA-A2-restricted peptide that has been targeted successfully in myeloid leukemia with immunotherapy. PR1 is derived from the neutrophil granule proteases proteinase 3 (P3) and neutrophil elastase (NE), which are both found in the tumor microenvironment. We recently showed that P3 and NE are taken up and cross-presented by normal and leukemia-derived APCs, and that NE is taken up by breast cancer cells. We now extend our findings to show that P3 and NE are taken up and cross-presented by human solid tumors. We further show that PR1 cross-presentation renders human breast cancer and melanoma cells susceptible to killing by PR1-specific CTLs (PR1-CTL) and the anti-PR1/HLA-A2 Ab 8F4. We also show PR1-CTL in peripheral blood from patients with breast cancer and melanoma. Together, our data identify cross-presentation as a novel mechanism through which cells that lack endogenous expression of an Ag become susceptible to therapies that target cross-presented Ags and suggest PR1 as a broadly expressed tumor Ag.

Cytokines, GM-CSF and IFNgamma administered by priming and post-chemotherapy cycling in recurrent ovarian cancer patients receiving carboplatin.

BACKGROUND: Monocyte/macrophages (MO/MA), a polymorphic population of innate immune cells, have the potential to mediate antitumor effects, and may also contribute to protumor effects. A priming and post-chemotherapy schedule of the myeloid cell mobilizing and immune stimulatory growth factor, granulocyte monocyte stimulating factor (GM-CSF, Leukine) and the MO/MA activating cytokine recombinant interferon gamma 1b (rIFN-gamma1b, Actimmune) has been developed. The pre- and post-chemotherapy design is based upon known in vivo kinetics and immune modulatory effects of these molecules. Carboplatin (Paraplatin) was selected as the cornerstone of treatment of epithelial ovarian cancer (EOC). METHODS: We studied hematopoietic and immunologic effects of GM-CSF and rIFN-gamma1b before and after carboplatin in patients with recurrent EOC. Potentially chemotherapy-sensitive patients with recurrent measurable tumors received subcutaneous GM-CSF (starting at 400 mug/day) for 7 days plus subcutaneous rIFN-gamma1b (100 mug) on days 5 and 7, before and after intravenous carboplatin (area under the curve of 5). We performed standard hematologic assessment and monitored monocyte (MO), dendritic cell, major cell subset counts, and antibody-dependent cell-mediated cytotoxicity (ADCC) against a Her2neu+ tumor cell line, as well as selected plasma inflammatory cytokine, chemokine and growth factor levels. RESULTS: Our analysis comprised only the first 3 months of treatment in the initial 25 patients. Relative to pretreatment baseline values, white blood cell, neutrophil, MO, and eosinophil counts increased (P