Adoptive cell transfer, in which a patient’s own immune defenses are boosted or rewired to kill cancer cells, is one of the most effective forms of personalized cancer care to ever reach patients. There are two types of adoptive cell transfer. In one type, immune cells called T cells are isolated, genetically modified, expanded, and returned to patients (e.g., CAR T cell therapy, TCR-modified T cell therapy). In the second type, the cells are expanded and infused back without genetic modification. The latter involves tumor-infiltrating lymphocytes or TILs – a naturally occurring, heterogeneous population of white blood cells that migrate into a tumor. TILs are known to be the most suitable immune cells to attack and destroy the cancer they homed in on. (For an introductory overview of the status and desirable evolution of TIL therapies, please refer to our previous article here.)
“Back in 1988, we published our first work showing that TILs isolated from patients with metastatic melanoma could be expanded in the lab and returned to the patient, where they mediated cancer regression,” stated Dr. Steven Rosenberg, chief of surgery at the U.S. National Cancer Institute, in a report by the American Association of Cancer Research (AACR) in 2018 (1). His decades-long research into TILs, along with multiple studies by other groups, have proven that TIL therapy shows significant, durable success in treating melanoma (2, 3). TIL therapy is now being explored for precision treatment of other types of solid cancers.
While it has been advanced over many years, the process of developing TIL therapies still suffers from certain challenges, particularly in the collection and processing of tumor samples used to extract TILs. This article attempts to lay bare some of these challenges and discuss how novel technological solutions can help overcome them.