Scientists have been trying to re-program or genetically modify human cells for many years, with limited success. Now, it seems that a team of scientists from University of Pennslyvania's Abramson Cancer Center has finally managed to crack the code and, the initial results are quite exciting.

For their experiment, the team led by Professor Carl June, chose to tackle Chronic lymphocytic leukemia (CLL) - a type of cancer that afffects the blood and bone marrow (the spongy tissue inside bones where blood cells are made). The disease which strikes about 50,000 people annually, can be controlled with the help of chemotherapy and even fully cured with a successful bone marrow transplant if, a perfect match is found which, in most cases is a little elusive.

To test their new groundbreaking treatment, the scientists drew blood from three patients suffering from an advanced stage of the cancer.

They then proceeded to extract the T-cells from each sample. While the normal role of these cells is to help fight infections, in people suffering from cancer, they are unable to distinguish between cancerous and healthy cells, hence allowing the diseased cells to spread like wildfire.

Then, the scientists fortified the extracted T-cells with a protein called Chimeric Antigen Receptor (CAR), and infused the blood back into each of the patients. The role of the CAR in the modified cells was to attract a protein called CD19 in the leukemia tumor cells and effectively destroy them. It also helped instigate the propagation of thousands of new T-cells which all joined in attacking the diseased cells. The scientists estimate that each modified T-cell was responsible for killing at least 1,000 cancer cells.

What was even more amazing is that in two of the patients the tumors disappeared completely in just three weeks, rendering them cancer-free for over a year now. While the 3rd patient still has a few cancer cells, his disease has improved tremendously and is responding well to chemotherapy.

Though this is an amazing breakthrough, doctors are a little cautious about calling it a complete victory over this deadly disease. For one, the sample size is considered too small and then there is the unknown about how the modified T-cells will react inside the body a few years down the road - Will they continue to protect the body or turn rogue and start attacking the healthy cells? There were also some side effects like the destruction of healthy infection fighting blood cells, which while controllable with medication, were a cause for concern. But no matter what happens, the killer T-cells are definitely a step in the right direction in our never-ending fight against this deadly disease.

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