Work Package 1 focused on monitoring the colonization of therapeutic bacteria and assessing the functionality of biosensors for externally administered molecules in 3D tumor spheroids. Despite technical challenges in adapting the MC38 cancer cell line, a robust protocol for bacterial colonization was established, and an imaging protocol was developed to visualize GFP-expressing bacteria within spheroids. Induction in bacteria colonizing spheroids was demonstrated. However, some deliverables, such as induction kinetics and induction of bacterial oncolytic activity in 3D tumor spheroids, were not achieved.
Work Package 2 aimed to characterize the toxicity, biodistribution, pharmacokinetics, and therapeutic activity of therapeutic bacterial strains. A standardized protocol for bacterial counting using flow cytometry was optimized, and toxicity studies showed a dose-response correlation between bacterial concentration and mouse weight loss. Inducer pharmacokinetics were investigated, confirming detectable levels in tumors, and the functionality of the sensor was validated in vivo using luciferase as a reporter. Therapeutic effectors were tested, but no significant effect on tumor growth was observed. Some deliverables, such as nduction of bacterial oncolytic and immunotherapeutic activity in vivo, were not fully achieved.
In summary, the project successfully established protocols for bacterial colonization and induction by externally administered molecules in spheroids, optimized bacterial counting methods, and validated biosensor functionality in vivo. However, further optimization of the induction process and exploration of combination therapies are needed to enhance the efficacy of inducible bacterial cancer therapy.
