Eradication of Heterogeneous Tumors by T-Cells Targeted with Combination Bispecific Chemically Self-Assembled Nanorings (CSANs)


 Cancer Stem-like Cells (CSCs) are often the root cause of refractive relapse due to their inherent resistance to most therapies and ability to rapidly self-propagate. Recently the antigen CD133 has been identified as a CSC marker on several cancer types and αCD133 therapies have demonstrated selective targeting against CSCs with minimal off-target toxicity. Theoretically, by selectively eliminating CSCs the sensitivity to bulk tumor targeting therapies should be enhanced. Previously, our laboratory has developed bispecific chemically self-assembled nanorings (CSANs) that successfully induced T-cell eradication of EpCAM positive tumors. We reasoned that targeting both CSCs (CD133+) and the bulk tumor (EpCAM+) simultaneously using our CSAN platform should produce a synergistic effect. We evaluated αCD133/αCD3 CSANs as both a single agent and in combination with αEpCAM/αCD3 CSANs to treat triple negative breast cancer (TNBC) cells which express a subpopulation of CD133+ cancer stem cells and EpCAM+ bulk tumor cells. Furthermore, an orthotopic breast cancer model validated the ability of αCD133 and αEpCAM targeting to combine synergistically in elimination of TNBC MDA-MB-231cells. Complete tumor eradication only occurred when EpCAM and CD133 were targeted simultaneously and lead to full remission in 80% of the test mice. Importantly, the depletion and enrichment of CD133 TNBCs highlighted the role of CD133 positive cancer cells in regulating tumor growth and progression. Collectively, our results demonstrate that dual targeting with bispecific CSANs can be effective against heterogenous tumor cell populations and that elimination of primary and CD133+ CSCs maybe necessary for eradication of at least a sub-set of TNBC.