TIL is a recently FDA approved therapy for treating certain types of metastatic cancer.  It has been referred to as a “living drug” as it is made up of the individual patients T lymphocytes.  It does so by taking cancer-targeting T cells from the patient’s own tumor and then growing them into billions more of the same cells in the lab and then re-infusing them into the patient.   This massive influx of warrior T cells can destroy the tumor whereas the previous small number of T cells were just holding it at bay.  

The initial FDA approval is for metastatic melanoma but it’s used for other solid tumors such as breast, pancreas and colon cancers.   

TIL is not the first use of immune cells to fight cancer.  CAR T-Cell therapy is another FDA approved method to fight certain “liquid” cancers, primarily leukemia, lymphoma, and multiple myeloma.  So far it has not proven effective for solid cancers.  CAR T-Cell therapy is so named because it involves making a chimeric antigen receptor (CAR) on T-cells.  It uses genetic engineering to modify the patient’s own T-cells so they can recognize (and then destroy) a specific cancer cell signal (antigen).  CAR-T therapy has helped and cured thousands of patients but one drawback of its use is that it is tricky to find a molecular signal (antigen) that is totally unique to the cancer.  Since healthy cells may also share this molecular signal, they can sometimes be damaged by the chimeric T-cells.  TIL on the other hand doesn’t modify the innate targeting system of the T-cells it simply uses a normal immune cytokine IL-2 (interleukin-2) to boost cell growth.  As it turns out one “target” that the TIL cells seem to pick out is the mutated protein that would otherwise control healthy cell growth.  Once this protein undergoes a Jekyll-Hyde transformation it allows uncontrolled cell growth otherwise known as cancer.