We propose to translate a novel cellular MRI technology to visualize the trafficking of cellular therapeutics against colorectal cancer (CRC). CRC accounts for approximately 150,000 new cases annually, and 6,000 of these are treated every year at the University of Pittsburgh Cancer Institute (UPCI). CRC patients with resectable liver metastases constitute a group of patients with a unique combination of an overall poor prognosis and a 5-year overall survival rate between 20-35%, despite the presence of only minimal residual disease. Immunotherapeutic interventions may potentially be effective in this patient population. Currently, a major type of cell-based therapy used for CRC and other cancer types uses dendritic cells (DCs) as live vaccines that deliver tumor-specific antigens to the lymph nodes thereby inducing endogenous killer T cells (i.e., cytotoxic T cells or CTLs) in patients. To date, the inability to see the cells in vivo following therapeutic cell transfer is one of the greatest bottlenecks in the development of cancer immunotherapy. A commonly cited reason for the highly varied clinical outcomes of current DC-based vaccines is sub-optimal DC delivery to the lymph nodes. Recently, the laboratory of Dr. Ahrens has demonstrated a compelling technology that makes transplanted cells visible via MRI. In this approach, cells are labeled ex vivo with a novel perfluoropolyether (PFPE) nanoparticle composition and then introduced into the patient. Cell migration is subsequently monitored in vivo using 19F MRI. The key advantage of this approach is that the 19F images are extremely selective for the labeled cells, with no background signal from the host's tissues. Furthermore, accurate cell quantification in regions of interest is possible. Data show that PFPE nanoparticles are highly biocompatible inside cells. To date, several in vivo imaging studies have been conducted in rodent models. A clinical-grade version of the enabling PFPE nanoparticle reagent has recently been formulated and manufactured by Celsense, Inc. Celsense is currently performing mandatory in vitro and animal safety studies of this reagent for eventual human use. The proposed studies will allow us to simultaneously advance the technology of in vivo tracking of cell therapy in humans, while giving insights into ongoing clinical studies of immunotherapy in CRC, directed by Drs. Kalinski and Bartlett at the UPCI. The proposed project has three Specific Aims: (1a) Establish PFPE labeling protocols for therapeutic cells. We will develop optimal tissue culture protocols for PFPE labeling of immunotherapeutic DCs. (1b) Determine in vitro characteristics of therapeutic cells following labeling with PFPE. We will rigorously evaluate the degree to which PFPE labeling induces any alterations in DC function and phenotype in vitro. (2a,b) study cell trafficking and PFPE clearance of labeled DCs in a rodent model. (3a) Implementation of sensitive 19F MRI/MRS methods on a 3T clinical MRI system. We will optimize pulse sequences and evaluate the minimum detectable cell numbers using phantom studies. (3b) Pilot study tracking immunotherapeutic cells in CRC patients. We will amend the existing UPCI CRC therapeutic protocol (UPCI 05-063;BB-IND 13,234) to include imaging of transferred cells. In a small cohort of CRC patients (n=6), we will image the migration of DC-based vaccines to the lymph nodes. We will follow their administration by the traditional intradermal route and a novel intralymphatic route developed to accelerate the DC delivery to the lymph nodes and to protect booster doses of DCs from elimination by the previously-induced CTLs. The proposed translational studies are the first effort to evaluate the potential of 19F MRI/MRS-based cell tracking for clinical use. Additionally, we will garner preliminary data critically important for improving the immunotherapeutic strategies in metastatic CRC and other forms of cancer. The Pittsburgh region has exceptional strength in cancer immunotherapy and imaging innovations. We have organized a potent research team from the region to conduct this project.
In this proposal we will use advanced magnetic resonance imaging (MRI) technology to visualize the trafficking of cellular immunotherapy against colorectal cancer. Most often applied to advanced cancer, where existing therapies have limited efficacy, cellular immunotherapy is the administration of specialized cells that kill cancer cells or produce immunity to the disease. Immunotherapy is positioned to become a fourth strategy in cancer treatment supplementing surgery, chemotherapy, and radiation. Currently, the inability to see cells in the body following inoculation is one of the greatest bottlenecks in the development of cancer immunotherapy. This proposal will adapt modern imaging tools to address this urgent need, while giving insights into ongoing clinical studies of immunotherapy in colorectal cancer.
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