Project description:BACKGROUND: While many authorities theorize that cancer vaccines are too weak to be widely effective, there are quite a few reports with clearly demonstrated, significant clinical benefit in some patients. The literature of cellular cancer immunotherapies shows that 53% (78/147) of phase II studies showed evidence of clinical activity. While not all reached their primary endpoints, 75% (12/16) of phase III studies had positive data. SV-BR-1-GM, derived from a patient with grade 2 (moderately differentiated) breast cancer, is a GM-CSF-secreting breast cancer cell line with properties of antigen-presenting cells we established. METHODS: We report detailed molecular and clinical findings from an open-label phase I, single-arm pilot study in breast (3 subjects) and ovarian (1 subject) cancer with irradiated SV-BR-1-GM cells (ClinicalTrials.gov Identifier NCT00095862). Inoculations of SV-BR-1-GM were preceded by low-dose cyclophosphamide and followed by injections of interferon-alpha2b into the SV-BR-1-GM inoculation sites. We assessed both cellular (delayed-type hypersensitivity (DTH) reactions) and humoral (anti-SV-BR-1 antibody) immune responses and conducted molecular analyses on patient blood cells and SV-BR-1-GM cells. RESULTS: Treatment was generally safe and well tolerated. Immune responses were elicited universally. Overall survival was more than 33 months for three of the four patients. As previously reported, one patient (Subject A002, with grade 2 breast cancer) had regression of metastases in lung, breast and soft tissue within 2 months of treatment initiation. At later relapse, with multiple metastases including several in the brain, rapid tumor response was again seen, including complete regression of CNS metastases. Consistent with a role of Class II HLA in contributing to SV-BR-1-GM’s mechanism of action, Subject A002 allele-matched SV-BR-1-GM at the HLA-DRB1 and HLA-DRB3 loci. Only the HLA-DRB1 alleles were clearly expressed in SV-BR-1-GM cells. However, interferon-gamma (possibly also present in situ) upregulated both HLA-DRB1 and HLA-DRB3 to substantial levels. Gene expression data supports the hypothesis that SV-BR-1-GM cells have retained some of the original breast cancer’s grade 2 character. CONCLUSIONS: We describe a whole-cell immunotherapy regimen with remarkable rapidity of response and a speedy rescue response, including complete resolution of CNS metastases after relapse. Class II HLA matches might be critical for SV-BR-1-GM’s therapeutic potential.

Project description:Background: Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) is a hematopoietic growth factor and adjuvant in cancer immunotherapy via stimulation of dendritic cells/APCs. However, GM-CSF has yielded inconsistent results and its role regarding in vivo modulation of macrophages remains underexplored. We previously demonstrated that 100ng “high-dose” intratumor (IT) GM-CSF ablated tumor blood vessels and worsened tumor hypoxia after 3 weeks through tumor-associated macrophage (TAM) soluble VEGFR-1 production in PyMT murine breast cancer. Here, we investigate a role for “low-dose” IT GM-CSF on tumor oxygen and the impact on immunotherapy response, TAMs/myeloid cells, and TILs relative to “high-dose”. Methods: We performed IT injections of dose-specific GM-CSF or saline controls and then evaluated phenotypic effects after 3 weeks. We used Electron Paramagnetic Resonance Oximetry to measure and image in vivo tumor oxygen in real-time, and fluorescent immunohistochemistry to assess tumor blood vessels. IT GM-CSF doses were tested in priming PyMT tumors for sensitization to PD1. We performed RNA Sequencing of TAM and CD8 TIL to observe transcriptional changes coupled with flow cytometry of peripheral blood monocytes, tumor myeloid, and TIL populations in immunology cold" PyMT tumors response to dose-optimized GM-CSF. Lastly, we assessed and compared effects of IT GM-CSF on TAM and TIL in an immunologically “hot” 4T1 breast cancer model. Results: 5ng IT GM-CSF significantly increased PyMT tumor oxygen without augmenting tumor growth and promoted tumor vessel health via increased pericyte coverage. Priming of PyMT tumors with 5ng IT GM-CSF (“low-dose”, hypoxia reduced) sensitized “cold” PyMT tumors to PD1, but this synergy was not observed with 100ng (“high-dose”, hypoxia exacerbated). Immunologically, 5ng GM-CSF did not increase monocyte mobilization or alter phenotypic marker expression on TAMs, but reduced hypoxic and inflammatory transcriptional programs in macrophages and CD8 TIL isolated from PyMT tumors. 100ng increased infiltration of myeloid cells and TAMs but these TAMs had reduced MHCII expression, suggesting support of immune-suppressive TAM under hypoxia. Some tumors exhibited increased CD8 polyfunctionality either dose suggesting mild CD8 TIL priming. On the other hand, 100ng in “hot” 4T1 tumors resulted in increased TAM MHCII and other immunostimulatory molecules with moderate increases in CD8 TIL polyfunctionality and exhausted PD1hiTIM3+ phenotype, indicating that GM-CSF may have opposing effects on macrophage modulation based on tumor immunological status.

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