Caveolae at the endothelial cells surface can selectively, rapidly, and actively pump targeted antibodies out of the bloodstream and into underlying tissue in vivo, even when they are conjugated to high-molecular weight cargo. Based on this exciting recent discovery, we also found that caveolae pumping system enables unprecedented tumor-specific targeting and penetration. Taken together, our evidence strongly supports that targeting tumor caveolae is a new strategy providing a portal to deliver therapeutic agents across the vascular endothelial cell barrier and directly into tumors. Caveolae can rapidly pump a targeted antibody with the attached cargo across the endothelial cells to reach concentrations inside solid tumors that greatly exceed maximum concentrations in the blood. In this project we will focus on testing of the therapeutic utility of the antibody- cisplatin-CMdextran immunoconjugates to target truncated form of Annexin A1 in tumor endothelial caveolae and to effectively penetrate solid tumors. The data will provide proof-of-principle of our innovative delivery strategy for therapy of lung cancer and moves toward clinical translation by assessing how well caveolae immunotargeting and pumping into tumors can enhance the therapeutic impact of chemotherapy. We will design, synthesize and asses in vivo the efficacy of cisplatin-carboxymethyl dextran (CMdextran)- AnnA1 antibody conjugate to create new tumor caveolae-targeted therapeutics for enhanced delivery and efficacy in lung cancer models using our advanced animal models. We hypothesize that by pumping antibodies armed with cisplatin- CMdextran into tumors, caveolae can rapidly and specifically concentrate therapeutic agents inside tumors and enhance tumor destruction with significantly reduced toxicity.
The Specific Aims of this project are:
Aim 1 - to characterize in vivo delivery of cisplatin immunoconjugates targeting EC caveolae in tumors, and Aim 2 - to assess therapeutic efficacy of the EC caveolae-targeting cisplatin immunoconjugates. This project will utilize our new intravital microscopy (IVM) tumor model system in addition to spontaneous mammary tumors from genetically engineered mice. IVM permits direct visualization of targeting and endothelial processing as well as stroma and tumor cell responses, all of which can be quantified to help provide new insights into therapeutic mechanisms in tumors. Targeting caveolae opens a specific gateway across the restrictive vascular endothelial barrier. It can provide means for enhanced delivery much closer to ideal targeting in order to achieve more effective therapies. We have demonstrated that AnnA1 is expressed in the vasculature and caveolae of human primary and metastatic lung tumors. Overall, our proposed project could create a paradigm shift away from the passive transvascular delivery that greatly limits drug efficacy in humans, affording the first prototype of caveolae-targeted anticancer therapeutics for future translation into the clinic.
Every year more than 200,000 new lung cancer cases are reported in the United States and more than 150,000 patients will die from this disease. Despite the high incidence and mortality rates, current lung cancer therapies are still relying upon systemically administered chemotherapeutic drugs that reach every organ of the patient's body. Unfortunately, due to the limited permeability of the vascular walls only a small fraction of the intravenously administered dose actually reaches tumors. This requires continuously increasing doses of the chemotherapeutic drugs in order to achieve at least some level of therapeutic efficacy and is often leading to multiple adverse side effects and drastically reduces quality of life of lung cancer patients. Thus, the efficacy of many systemically administered breast cancer therapies is seriously compromised by the significant barriers that inhibit drug delivery. The overall objective of this study is to use our newly discovered mechanism, the caveolae pumping system, in order to provide an effective solution to the cisplatin delivery and toxicity problems for patients with lung cancer. We discovered the unique mechanism for therapeutics to traverse the blood vessel barrier and designed a strategy that could significantly enhance therapeutic effectiveness while decreasing toxicity of anticancer therapeutics. With support of this grant application, we plan to produce antibody-cisplatin immunoconjugates, the hitherto unknown drug candidates with high therapeutic efficacies and greatly reduced systemic toxicity, ultimately offering delivery platform for safe, effective lung cancer therapy.