Enhancing the Anticancer Activity of Attenuated Listeria monocytogenes by Cell Wall Functionalization with "Clickable" Doxorubicin

Among bacteria used as anticancer vaccines, attenuated Listeria monocytogenes (Lmat) stands out, because it spreads from one infected cancer cell to the next, induces a strong adaptive immune response, and is suitable for repeated injection cycles. Here, we use click chemistry to functionalize the Lmat cell wall and turn the bacterium into an "intelligent carrier" of the chemotherapeutic drug doxorubicin. Doxorubicin-loaded Lmat retains most of its biological properties and, compared to the control fluorophore-functionalized bacteria, shows enhanced cytotoxicity against melanoma cells both in vitro and in a xenograft model in zebrafish. Our results show that drugs can be covalently loaded on the Lmat cell wall and pave the way to the development of new two-in-one therapeutic approaches combining immunotherapy with chemotherapy.