Chemotherapeutics are a frontline treatment for lymphoma, but systemic drug therapy, either in free drug or nanoparticle form, achieves limited penetration of high tumor burdens in lymphoid tissues while introducing dose-limiting toxicity in off-target organs. We aim to specifically deliver chemotherapy into lymphoma tumors by conjugating chemotherapeutic-loaded nanoparticles onto the surfaces of T cells ex vivo. We hypothesize that, following adoptive transfer, the T cells will homeostatically migrate into tumor-bearing lymphoid organs while carrying their nanoparticle cargo. This cell-mediated shuttling of chemotherapeutic nanoparticles would reduce toxicity in off-target organs affected by systemically administered chemotherapy or non-cell tethered nanoparticles.

In vitro T cell cultures were generated by activating splenocytes with conA and IL-2. Doxil, a clinically-approved liposomal formulation of doxorubicin (dox), was used as a model chemotherapeutic nanoparticle due to its high drug load and slow release characteristics. Doxil was functionalized with maleimide groups, which chemically conjugate to surface thiol groups on the T cells, resulting in stable liposome tethering to the surfaces of live cells. We adoptively transferred maleimide Doxil liposome-carrying Thy1.1 T cells into BL6 mice bearing disseminated GFP Emu-myc lymphoma tumors, an orthotopic model of aggressive B cell lymphoma, then assessed T cell and liposome biodistribution by whole animal imaging, flow cytometry and immunohistochemistry. Tumor burden in lymphoid organs was measured by flow cytometry.

In vitro survival studies showed that activated T cells tolerate dox over a higher concentration range than lymphoma cells. This suggested a therapeutic window in which relevant doses of dox can be delivered by T cells without premature death of the carrier cell. Post adoptive transfer, T cells were detectable in lymph nodes and spleen as early as 24 h and continued to accumulate over a few days. Trafficking kinetics were similar regardless of whether T cells were unmodified or liposome-functionalized, and whether the recipients were healthy or tumor-bearing mice. Analysis of tumor-free and tumor-bearing lymphoid organs in recipients showed maleimide-Doxil liposomes localized on transferred T cells, interspersed throughout the organs. Treatment of tumor-bearing mice with maleimide Doxil-carrying T cells resulted in mild reductions in tumor burden using minute quantities of dox; ongoing studies are exploring the impact of increased dox dose per carrier T cell.

In conclusion, we have demonstrated that T cells can be stably functionalized with doxorubicin liposomes and subsequently transport these liposomes into lymphoma tumors in vivo. This cell-mediated delivery approach is adaptable to other nanoparticle systems and may be a versatile technique for specific delivery of materials into lymphoid organs and lymphoma tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4432. doi:10.1158/1538-7445.AM2011-4432