This month doctors reported that one of their patients, a woman with advanced colon cancer, is now cancer-free thanks to TIL therapy.
It works like this: doctors extract cancerous cells and identify the mutations that make them dangerous, and simultaneously harvest lots of TILs. They comb through the TILs looking for the ones whose attack mechanism matches the mutation causing the cancer. They then multiply those cells and re-inject hundreds of billions of them into the patient, along with a dose of interleukin-2, a compound that helps white cells work.
These doctors did this with two patients. One is dead, and one seems cancer free. The bad news is that they think the therapy only worked because of some extreme genetic luck:
Ms. Ryan’s tissue turned out to be a medical gold mine. She had a KRAS mutation and her TILs included killer T-cells that locked onto the mutation like guided missiles.Since not everybody can be lucky, the future of this therapy is in genetically engineering lymphocytes to target the dangerous mutation.
Her T-cells were able to recognize the mutation because she has an uncommon tissue type, which is a genetically determined trait. As a result, she carries a certain protein on the surface of her cells that plays an essential role in displaying the KRAS mutation so that cancer-killing cells can find it and attack.
Such therapies are years or even decades away from being deployed on a large scale, but I can't think of any reason why they shouldn't work most of the time. As I have said before, our ever-increasing understanding of genetics and ever increasing skill at genetic manipulation makes me a cancer optimist.