Immunotherapy has shown so much promise that the journal Science called it the biggest scientific breakthrough of 2013. The editors said we are at a turning point “as long-sought efforts to unleash the immune system against tumors are paying off” with a growing number of patient success stories. Immunotherapy drugs work by either stimulating specific parts of the immune system or by counteracting cancer cells signals that prevent immune response
The idea to harness our immune system to treat cancer dates to the late 1800s when Dr. William Coley, a New York surgeon, found that the tumors of some cancer patients shrunk if the patient got an infection after surgery. Coley developed a way to induce fever to stimulate immune response, but his approach was abandoned as radiation therapy took hold.Research into immunotherapy picked up significantly in the mid- to late 1900s. After hundreds of clinical trials and many more hours in the lab, researchers began to identify the mechanisms that would make immunotherapy work. One of the biggest discoveries was finding that certain molecules on T-cells would shut off when met with cancer cells. Researchers have developed drugs to stop these molecules from switching off and keep the immune system running.
In 2011, the FDA approved the first “checkpoint inhibitor” immunotherapy drug, ipilimumab (Yervoy®), for metastatic and advanced melanoma. Other drugs work similarly, but target different molecules. Pembrolizumab (Keytruda®) focuses on a programmed death 1 protein (PD-1) found on T-cells. The FDA recently approved it for advanced melanoma and it’s being studied for other cancer types. Nivolumab (Opdivo®) has been effective for some melanoma patients, as well as patients with kidney cancer and non-small cell lung cancer.
Checkpoint inhibitors are just one type of drug in a broad class of immunotherapies, which also includes:
Cancer vaccines: Used to help prevent or treat cancer, vaccines are injected substances that kick-start immune response against certain diseases. Sipuleucel-T (Provenge®) is the only FDA-approved vaccine to treat cancer, specifically advanced prostate cancer that has stopped responding to hormone therapy. Gardasil®, Gardasil 9® and Cervarix® are preventive vaccines against cervical cancer.
Cytokines: These proteins occur naturally in our bodies in small amounts and serve as messengers to signal the immune system. For example, the cytokine known as interleukin-2, is available through the drug aldesleukin (Proleukin®) in much larger quantities than what our bodies can make. The drug helps the body generate super-charged cancer-killing immune cells. Aldesleukin is FDA-approved for patients with metastatic kidney cancer and metastatic melanoma.
