A new cancer therapy has been recently described in the New England Journal of Medicine, and Science Translational Medicine. The therapy is based on the idea that T cells, the frontline fighters of the human immune system are quite good at their job, which is recognizing intruding cells and starting a cascade of events that will eventually lead to their demise. So, engineering these cells to recognize cancer cells could be a good start in the fight against cancer.
This, however proved to be quite difficult.
Now, a research group at Pennsylvania University has designed a new gene that can be introduced into T cells, through a lentivirus vector, to make them attack cancerous B cells, which is are the cause of chronic lymphoid leukemia (or CLL). The newly designed gene encodes for a receptor that recognizes a molecule, which is uniquely expressed by cancerous B cells. When such a genetically engineered T cell binds one of the cancerous cells, it will eventually lead to its destruction.
This method was tested on three patients in an initial clinical trial, where a sample of patient T cells had the new gene added before they were infused back into the blood of the patient.
All three patients have improved dramatically, and two of them are currently in complete remission. (For an account by one of the trial participants, click here.)
Each modified T cell killed at least thousand tumor cells, leading several media outlets to dub them ‘serial killer cells’. A blood test taken one year after the administration of the designed T cells revealed that these were still present in the blood of the patients and still able to kill cancer cells, which is one of the great advantages of this therapy. One doesn’t need to be given drugs once a week or so, because these are living, dividing cells that only need to be infused once, after which they survive and multiply, continuously protecting against cancer. It's explained in the following video.
This exciting new development potentially opens up the door to treatments for several other cancers as well. One could imagine breast cancer specific T cells, prostate cancer specific T cells, and so on if a viable receptor-target duo can be found.
Two remarks, however, are that (1) three patients is a small sample size, and (2) longer monitoring is needed to ensure that the cancer cells do not mutate and escape the attention of the modified T cells.
Nevertheless, this is an exciting development, which, after additional research, could provide a powerful new tool in the fight against cancer.
ReferencesKalos, M.; Levine, B.L.; Porter, D.L.; Katz, S.; Grupp, S.A.; Bagg, A. and June, C.H.(2011). T Cells with Chimeric Antigen Receptors Have Potent Antitumor Effects and Can Establish Memory in Patients with Advanced Leukemia. Science Translational Medicine. 3(95), p. 95ra73. doi:10.1126/scitranslmed.3002842.
Porter, D.L.; Levine, B.L.; Kalos, M.; Bagg, A. and June, C.H. (2011). Chimeric Antigen Receptor-Modified T Cells in Chronic Lymphoid Leukemia. The New England Journal of Medicine. Published August 10. doi: 10.1056/NEJMoa1103849.