Exciting Treatment Harnesses the Immune System

Immunotherapy is a wonderful testament to the benefits that arise from our growing understanding of the incredibly intricate human immune system. Consider, for example, treatment using tumor-infiltrating lymphocytes, or TILs.

Scientists have known for decades that the presence of these immune cells in cancerous tumors is associated with better health outcomes, but not until more recently did they understand why. Compounding the challenge to learn more was the fact that, for a long time, tumor immunology was considered a soft science, with these approaches dismissed as alternative medicine.

As we learned that cancer can affect the body’s immune responses and realized rare victories with early immune stimulators such as interferon and interleukin-2, the field of immunotherapy was revived. Newer tools emerged, including drugs known as monoclonal antibodies that target specific proteins to stimulate the immune system. In addition, genetic analysis enabled scientists to identify separate classes of T cells and learn about their unique cancer-fighting abilities.

The location of certain T cells also attracted attention: Why would lymphocytes swarm specifically around tumor cells? This observation, along with new knowledge about the different types of immune cells and the cancer-driving proteins they fight, shed light on why TIL-infiltrated tumors were linked with a better prognosis. Armed with that understanding, scientists created an immunotherapy technique that harnessed the power of TILs to treat numerous cancer types, an experimental strategy discussed in an article in this special issue of CURE®.

With this strategy, scientists remove TILs from a patient’s tumor and select the ones best able to fight the disease — those that naturally bind to antigens created by cancer-driving genes. Then the scientists multiply the TILs in a lab through exposure to interleukin-2, which stimulates the cells’ growth, finally reinfusing them into the patient.

There is still a hit-or-miss element to TIL-based therapy — not everyone has a good response, and many techniques are being tried and refined. The work is laborious and requires time to isolate and grow the TILs, which can be too long a wait for some patients with rapidly growing cancers. To address that problem, companies are trying to move this effort from small-bandwidth academic laboratories to scaled-up commercial facilities. As these processes become standardized, it is our hope that the time needed to create ready-to-use cells, along with the cost of the technology, will drop as the success rate rises.

With many of the nation’s top academic and communithy centers conducting clinical trials in this area, TIL therapy seems poised to make strides in the next couple of years. It will be exciting to watch this strategy move toward wider availability.