Neo R/TIL Gene Marking - In 1989, using Neo R/TIL protocol, the first gene marked immune cells (tumour infiltrating lymphocytes =TIL) were successfully transferred into patients with advanced cancer. The TILs are those lymphocytes that are isolated directly from tumour and are then grown to large numbers in tissue culture in the presence of T cell growth factor (interleukin-2 = IL-2).

In Neo R/TIL protocol, an aliquot of cells from TIL is taken; a markers gene is transferred to these cells (the marker gene is neomycin resistance gene = Neo R) using retroviral vector; the marked cell and unmarked cells are grown together and then transferred back to the patient.