Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells.

Purpose: In vivo immune cell tracking using MRI can be a valuable tool for studying the mechanisms underlying successful cancer therapies. Current cell labeling methods using superparamagnetic iron oxide (SPIO) lack the persistence to track the fate and location of transplanted cells long-term. Magnetospirillum magneticum is a commercially available, iron-producing bacterium that can be taken up by and live harmoniously within mammalian cells as magneto-endosymbionts (MEs).

Quantitative MRI cell tracking of immune cell recruitment to tumors and draining lymph nodes in response to anti-PD-1 and a DPX-based immunotherapy.

DPX is a unique T cell activating formulation that generates robust immune responses (both clinically and preclinically) which can be tailored to various cancers via the use of tumor-specific antigens and adjuvants. While DPX-based immunotherapies may act complementary with checkpoint inhibitors, combination therapy is not always easily predictable based on individual therapeutic responses. Optimizing these combinations can be improved by understanding the mechanism of action underlying the individual therapies.

Unique depot formed by an oil based vaccine facilitates active antigen uptake and provides effective tumour control.

Background: Oil emulsions are commonly used as vaccine delivery platforms to facilitate slow release of antigen by forming a depot at the injection site. Antigen is trapped in the aqueous phase and as the emulsion degrades in vivo the antigen is passively released. DepoVax™ is a unique oil based delivery system that directly suspends the vaccine components in the oil diluent that forces immune cells to actively take up components from the formulation in the absence of passive release.

Using MRI cell tracking to monitor immune cell recruitment in response to a peptide-based cancer vaccine.

Purpose: MRI cell tracking can be used to monitor immune cells involved in the immunotherapy response, providing insight into the mechanism of action, temporal progression of tumor growth, and individual potency of therapies. To evaluate whether MRI could be used to track immune cell populations in response to immunotherapy, CD8 cytotoxic T cells, CD4 CD25 FoxP3 regulatory T cells, and myeloid-derived suppressor cells were labeled with superparamagnetic iron oxide particles.

Methods: Superparamagnetic iron oxide-labeled cells were injected into mice (one cell type/mouse) implanted with a human papillomavirus-based cervical cancer model.

Using lymph node swelling as a potential biomarker for successful vaccination.

There is currently a lack of biomarkers to help properly assess novel immunotherapies at both the preclinical and clinical stages of development. Recent work done by our group indicated significant volume changes in the vaccine draining right lymph node (RLN) volumes of mice that had been vaccinated with DepoVaxTM, a lipid-based vaccine platform that was developed to enhance the potency of peptide-based vaccines. These changes in lymph node (LN) volume were unique to vaccinated mice.