Delayed Progression of Lung Metastases Following Delivery of a Prodrug-activating Enzyme.

Anticancer research

PubMedID: 28476782

Dore-Savard L, Chen Z, Winnard PT, Krishnamachary B, Raman V, Black ME, Bhujwalla ZM. Delayed Progression of Lung Metastases Following Delivery of a Prodrug-activating Enzyme. Anticancer Res. 2017;37(5):2195-2200.
BACKGROUND
Chemotherapy is an effective option to treat recurrent or metastatic cancer but its debilitating side-effects limit the dose and time of exposure. Prodrugs that can be activated locally by an activating enzyme can minimize collateral damage from chemotherapy. We previously demonstrated the efficacy of a poly-L-lysine-based theranostic nanoplex containing bacterial cytosine deaminase (bCD) that locally converted 5-fluorocytosine (5-FC) to the chemotherapeutic agent 5-fluorouracil in MDA-MB-231 primary tumor xenografts.

MATERIALS AND METHODS
Here we used a more effective variant of bCD to target metastatic red fluorescence protein expressing MDA-MB-435 cells in the lungs. We used an intravenous injection of tumor cells and monitored tumor growth in the lungs for 5 weeks by which time metastatic nodules were detected with optical imaging. The animals were then treated with the bCD-nanoplex and 5-FC.

RESULTS
We observed a significant decrease in metastatic burden with a single dose of the enzyme-nanoplex and two consecutive prodrug injections.

CONCLUSION
These results are a first step towards the longitudinal evaluation of such a strategy with multiple doses. Additionally, the enzyme can be directly coupled to imaging reporters to time prodrug administration for the detection and treatment of aggressive metastatic cancer.