Arming T Cells with Homing Devices

With CAR technology, excitement looms over potential “fifth pillar” of cancer treatments.

Surgery, chemotherapy, radiation, and targeted therapies: these comprise the foundation of today’s cancer treatment armamentarium. Recently, however, an exciting fifth option has emerged — immunotherapy, which leverages the body’s immune system to fight the cancer.

One promising form of immunotherapy, which has been making noise recently with encouraging clinical results, hooks patients’ immune cells to a GPS that helps them find tumor cells. Known as chimeric antigen receptor (CAR) technology, the strategy leverages the fact that white blood cells called T cells can attack and kill cancer cells.

Smart cancer cells, however, have devised ways to hide from T cells. So scientists are identifying methods that help the T cells better recognize and hone in on tumors.

With CAR technology, T cells are removed from a patient and genetically modified so they are attracted to proteins made by tumor cells. The engineered T cells are then multiplied in the lab until they number in the billions and subsequently put back into the patient, where they can now hunt down the tumor cells.

Since CAR T cells are essentially a living therapy, the engineered cells can grow and thrive in the body until they have defeated the tumors.

The technology is adaptable based on the cancer being treated. For a lymphoma caused by malignant B cells, for instance, the T cell might be tweaked to recognize a protein commonly found on B cells. Whereas to treat myeloma, the T cell should be attracted to something myeloma cells pump out. And solid tumors such as pancreatic or brain cancers should be treated with T cells that are drawn to proteins found on these types of cells.

Unlike targeted therapies, which, as their name suggests, shut down a single target, immunotherapies like CAR T cells are likely to have more widespread effects. Cancer cells often dampen the response of several types of immune cells. But T cells that are actively fighting tumor cells are able to reactivate these dormant immune cells and recruit them into the attack. With more immune soldiers in the fight, the body may have a better chance at victory.