The immune system is the body’s first-line defense against invaders like viruses, bacteria and cancers. It helps protect us from getting sick and promotes healing when you are. Yet, despite the wonderful work the immune system does, at times it needs a helping hand. This is the case for cancer. That helping hand is called cancer immunotherapy.

Cancer immunotherapy is a form of cancer treatment that utilizes the body’s own immune system to combat cancer cells. It works by either boosting the immune system’s ability to identify and attack cancer cells or by providing the body with additional tools, like antibodies to enhance the immune response. Suffice it to say that cancer immunotherapies have transformed the treatment of dozens of cancers and extended the lives of millions of patients.

One type of cancer immunotherapy that have received a great deal of attention in recent years involves what is known as immune checkpoint inhibitors. Clinical research into such inhibitors have been fruitful, resulting in FDA-approved treatments for more than 25 cancer types.

The science began in the early 2000s, when Arlene Sharpe and Gordon Freeman, along with their colleagues at Harvard Medical School and the Dana-Fisher Cancer Institute, found that some cancers could evade detection and destruction by the body’s immune system defenses by disrupting an immune pathway called PD-1/PD-L1. The researchers found that by blocking or genetically deleting either of the molecules in either of these two pathways, they could boost T-cell immune activity, helping to restore the body’s ability to find and defeat tumors in animal models.

Scientists at multiple biopharmaceutical companies built on these critical insights. One of those scientists are Ira Mellman, whose team at Genetech developed an anti-PD-L1 antibody, prepared it for clinical trials, and helped bring the drug to FDA approval in the US. Mellman is now President of Research at the Parker Institute of Cancer Immunotherapy.