P53 containing natural nanovesicles of xenogenic origin as highly effective oncology therapy demonstrated in syngeneic murine model.

TP53 mutation is a hallmark of a majority of cancer cases. It is a natural target for cancer therapy. Unfortunately, multiple attempts to introduce exogenous p53 to restore its activity in cancer cells and induce their apoptosis have been failed.

The main challenges are:

1. Efficient delivery of p53-expressing construct to cancer cells.

2. Inhibition of WT-p53 via the dominant negative effect of mutant-p53

· It has been only recently discovered that corneal epithelial cells actively secrete nanovesicles containing p53 into the extracellular space. They are re-captured by neighboring epithelial cells and play role in local corneal anti-cancer defense. Being an immune-privileged tissue, corneal epithelium lacks mechanisms of innate and adaptive immunity and has to fully rely on local anti-oncogenic functions. We established a novel therapeutic approach based on this principle, translating an ancient local anti-oncogenic defense mechanism to modern systemic anti-cancer treatment.

· We use nanovesicles containing WT-p53 harvested from corneal epithelial cells. In order to prevent inhibition of exogenous WT protein via the dominant negative effect of mutant-p53, we use non-human p53 whose C-terminal domain responsible for tetramerization is different. This way exogenous WT-p53 is not suppressed even at high concentrations of mutant-p53.

· Our nanovesicles obtained from chicken corneal epithelial cells have average size of 150nm. We demonstrate their anti-cancer activity in-vitro in multiple malignant cell lines. Cell lines with mutant-p53 are significantly more sensitive to our treatment than those with WT-p53. Moreover, UV irradiation of corneal epithelial cells significantly increased anti-cancer effect, indirectly support p53 mechanism of action. Using mice syngeneic model, we show that our nanovesicles injected systemically, significantly prolong survival, reduce metastasis and tumor volume with no adverse effects.