Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2012. / Cataloged from PDF version of thesis. Page 175 blank. / Includes bibliographical references (p. 161-174). / Immunostimulatory therapies that activate immune response pathways are of great interest for overcoming the immunosuppression present in advanced tumors. Agonistic antibodies against the co-stimulatory receptors CD40 and CD137, Toll-Like Receptor (TLR) ligands such as CpG oligonucleotides, and immunostimulatory cytokines such as IL-2 have all previously demonstrated potent, synergistic anti-tumor effects. However, the clinical use of such therapies is significantly hampered by the severe, dose-limiting inflammatory toxicities provoked upon systemic exposure. We hypothesized that by anchoring immunomodulatory agents to lipid nanoparticles we could retain the bio-activity of therapeutics in the local tumor tissue and tumordraining lymph node, but limit systemic exposure to these potent molecules. We first prepared liposomes bearing surface-conjugated anti-CD40 and CpG and assessed their therapeutic efficacy and systemic toxicity compared to soluble versions of the same immuno-agonists, injected intratumorally in established solid tumors in mice. Anti-CD40/CpG-coupled liposomes significantly inhibited primary tumor growth and induced a survival benefit similar to locally injected soluble anti-CD40+CpG. Biodistribution analyses following local delivery showed that the liposomal carriers successfully sequestered anti-CD40 and CpG in vivo, reducing leakage into systemic circulation while allowing draining to the tumor-proximal lymph node. Contrary to locally administered soluble immunotherapy, anti-CD40/CpG liposomes did not elicit significant increases in serum levels of ALT enzyme, systemic inflammatory cytokines, or overall weight loss, confirming that off-target inflammatory effects had been minimized. Thus, these results confirmed the development of a delivery strategy capable of inducing robust antitumor responses concurrent with minimal systemic side effects. We next assessed the dissemination of the tumor-specific immune response that had been primed by locally administered, liposome-conjugated therapy. Since anti-CD40/CpG-coupled liposomes were unable to consistently induce the rejection of a secondary distal tumor challenge, we adapted the strategy of liposome-coupled delivery for the administration of anti-CD 137 and IL-2, two potent T cell-stimulatory agents. Local intra-tumoral therapy using anti-CD137-liposomes + IL-2-liposomes induced the highly potent inhibition of primary treated tumors and achieved a majority of complete cures, while successfully minimizing systemic exposure and eliminating symptoms of inflammatory toxicity, including lethality. In addition, 100% of anti-CD 137 + IL-2 liposome-treated mice were protected against a secondary distal tumor challenge, and demonstrated a significant delay in the progression of simultaneously inoculated, distal untreated tumors. Subsequent analyses confirmed that anti-CD137-liposomes and IL-2-liposomes bound specifically to cytotoxic T cells (CTLs) within the treated tumor, and that the depletion of CTLs abrogated the therapeutic anti-tumor response. Overall, these results indicated the effective local priming of an adaptive tumor-specific response, capable of mediating local, systemic, and memory anti-tumor immunity. The versatility of this liposome conjugation strategy suggests that we have developed a generalizable tool enabling the local delivery of highly potent immunomodulatory agonists in the absence of systemic toxicity, which could substantially improve the clinical applicability of such agents in cancer therapy. / by Brandon Kwong. / Ph.D.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/76115 |
| Date | January 2012 |
| Creators | Kwong, Brandon (Brandon Wai-Sing) |
| Contributors | Darrell J. Irvine., Massachusetts Institute of Technology. Dept. of Biological Engineering., Massachusetts Institute of Technology. Dept. of Biological Engineering. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 175 p., application/pdf |
| Rights | MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission., http://dspace.mit.edu/handle/1721.1/7582 |
Page generated in 0.0021 seconds