Two years back, when the wet lab got operational, we wanted to create a benchtop platform for cancer metastasis that would encompass all the complexity but be simple to execute. Our goal was to understand the differential functional properties of proliferating tumor cells against metastatic tumor cells and then exploit that knowledge for both discovery and diagnostic approaches.
We had initially divided metastasis into four functional stages, the initial shedding of tumor cells from the primary tumor, the eventual invasion of epithelium and endothelium, followed by the cells ability to survive and extravasate out of the blood vessel, and finally, the successful formation of micro and macro metastasis. Most drug discovery approaches centred around the first two steps, and minimal biology of the latter two was exploited, thereby making the identification of rate-limiting steps further downstream of the metastatic cascade necessary.
We started with colorectal cancer and characterised four tumor cell lines with varying metastatic potential across our platform of assays. We then genetically engineered the wild-type tumor cells to create metastatic clones of non-metastatic and non-metastatic clones of metastatic cells. According to their metastatic potential, the pattern of phenotypic and functional differences between wild-type colon cancer cell lines translated among the engineered cell lines. This pattern emergence helped establish a definite topography of cellular properties directly or indirectly proportional to the metastatic ability. Next, we examined the primary tumors of treatment naïve colorectal cancer patients. We could also identify similar patterns, suggesting that the topology identified in the cell lines was translationally significant among patients.
Next, we extrapolated our learning from colorectal cancer to triple-negative breast cancer and created a similar system with triple-negative breast cancer cell lines, both wild type and engineered. Surprisingly, though genetically very different, there was a more than 70% similarity in the functional properties of colorectal and triple-negative samples between both the metastatic and non-metastatic forms. We subsequently assigned weightages to the functional assays and identified strategically necessary steps for metastatic success.
We tested our hypothesis by repurposing ten approved drugs against our assay platform, emphasising the rate-limiting steps we identified. We selected the best hit out of these ten compounds. We tested its ability to inhibit liver metastasis in a proprietary orthotopic spontaneous metastasis animal model that we have jointly developed with Immunobiome Inc. Not surprisingly, almost 100% inhibition of liver metastasis was observed following six weeks of treatment, with little effect on the primary tumor. Next, we identified a key target from our understanding of rate-limiting steps and validated them in cell lines and patient samples with tool compounds. Genetic validation of this target confirmed our hypothesis.
Currently, we are working with multiple partners to create a pipeline for drug repurposing and novel drug discovery. We are also starting our first-in-class targeted therapy programme with our identified target and generating further proof of concept to enable a repurposed clinical candidate for additional trials.
Mestastop presented most of this work across four international conferences; two in the American association of cancer research annual meeting (AACR 2021), one in the European association of cancer research yearly meeting (EACR 2021) and another in the Metastatic Research Society meeting (MRS 2021).
