CRC2631 Takes on Pancreatic Cancer

A cancer diagnosis is life altering enough but a pancreatic cancer diagnosis is downright terrifying and rightly so. The National Institutes of Health report that from 2005-2011, the most current data available, that the 5-year survival rate for pancreatic cancer was 7.2%. By comparison, the 5-year survival rate for female breast cancer over the same period was 89.4%. To put these rates in perspective, the lifetime risk of a woman developing breast cancer is 12.3% and female breast cancer makes up 6.8% of all cancer deaths, while the lifetime risk of developing pancreatic cancer for men AND women is only 1.5% (8x less) yet the disease makes up a nearly identical 6.9% of all cancer deaths.

 

An 89.4% 5 year survival rate for breast cancer among women speaks to the great strides that have been made in cancer treatment in the last couple of decades. However, pancreatic cancer patients have largely failed to benefit from these advances. Pancreatic cancer remains something of an “orphan disease.” Receiving far less funding and attention than most other cancer types and current treatments (chemotherapy, radiation & surgery) are often unable to gain the upper hand against this swift moving cancer. At the Cancer Research Center we find this disparity in research efforts and treatment tools a call to action.

 

Thinking back over our successes with melanoma, prostate, breast and colon cancer we realized that our therapeutic Salmonella strain CRC2631 might just be what the pancreatic cancer treatment field has been waiting for. To put CRC2631 to the test we first chose two pancreatic cell lines to serve as a test model for how a patient’s body would react to this developing treatment. The first cell line, PANC-1 is a normal pancreas duct cell line and the second hTERT-HPNE, is a cancerous pancreatic duct cell line.

 

The first hurdle CRC2631 needed to clear as a viable pancreatic cancer treatment was to demonstrate an ability to invade pancreatic cancer cells while differentiating cancerous cells from normal cells. To do this, a pilot study was conducted in which normal and cancerous pancreas cells were incubated with CRC2631 for 30 minutes and two hours to allow the therapeutic Salmonella the opportunity to invade the pancreas cells. After the designated time had elapsed the media was removed, the cells were washed and new media containing the antibiotic gentamicin was added. After incubating for an additional 40 minutes the antibiotic media was removed and the pancreas cells were broken open, serially diluted and plated.

 

In this elegantly simple system, the antibiotic kills all therapeutic Salmonella that are not “safely” inside a pancreas cell at the end of the incubation. Therefore, when the pancreas cells are broken open and the cell slurry is diluted and plated, any bacterial colonies that grow overnight are derived from therapeutic Salmonella that have successfully invaded. A series of controls and standards allows us to use these colony counts to calculate the percentage of the bacterial population able to successfully invade the pancreas cells.

 

Reviewing the data from the invasion assays revealed several familiar patterns illustrated in the figure below. The first pattern to emerge was the invasion of normal pancreas cells (blue) by CRC2631 levels off between 30 minutes and 2 hours. This is a very good sign that there is nothing actively attracting CRC2631 to the normal pancreas cells. This also fits with what we observe in successful time course experiments with other cancer types. With certain cancer types, melanoma for example, we observe an initial attraction and a small reduction in the number of normal cells and then CRC2631 “loses interest” and the normal cell population rebounds.

 

The second familiar pattern was the invasion of pancreatic cancer cells (red) by CRC2631 increases two fold between the 30 minutes and 2 hours. This a very good sign that the cancer cells have attracted CRC2631’s “attention.” The increasing invasion of CRC2631 into the pancreatic cancer cells over time fits with the progressive targeting and killing we have observed in time course microscopy experiments with other cancer types.

 

The final familiar pattern is the invasion percentages themselves are similar to those we have seen with other cancer types. This is a good indication that CRC2631 will successfully target pancreatic cancer cells just as it has successfully targeted the other cell types we have tested.

 

The next hurdle in our quest to hone CRC2631 into a viable pancreatic cancer treatment is to demonstrate its pancreas tumor-targeting prowess in a time course microscopy study. In this study, CRC2631 will be incubated with normal and cancerous pancreas cells over 24 hours and samples taken at regular intervals to provide snapshots of the interaction. The appearance of the pancreas cells (indicates cellular health), where the Salmonella chooses to congregate (shows targeting) and changes to the cell population size over time (killing or growth) will provide much insight into the efficiency of CRC2631 as a pancreatic cancer treatment.

 

Each time we expand the range of CRC2631 as a therapy to a new cancer type we are standing on the shoulders of all we have learned thus far. In this way, even though pancreatic cancer is an uncharted territory we are not without a North Star. The Cancer Research Center is very grateful to our generous donors for providing the funding that allows us to continue to explore and build on our successes as we close in on the ultimate goal of sharing CRC2631 with the world as a non-toxic cancer treatment.

Alison Fea
Senior Technician & Laboratory Manager, Cancer Research Center

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