For the last few years, one of the hottest topics in cancer research has been immunotherapy. Immunotherapy is a type of treatment designed to boost the body's natural defenses to fight cancer. This year, doctors and scientists at the ASCO Annual Meeting have been talking about a type of immunotherapy called PD-1 inhibitors.
PD-1 is found on the surface of T-cells, which are a type of white blood cell that directly helps body’s immune system fight disease. Because PD-1 keeps the immune system from destroying cancer cells, blocking PD-1 allows the immune system to better eliminate the disease.
Last year, PD-1 inhibitors like nivolumab (Opdivo) and pembrolizumab (Keytruda) were approved by the U.S. Food and Drug Administration (FDA) for the treatment of advanced melanoma. Researchers are now looking to see if these drugs can improve the care of people with other types of cancer.
“The field of targeted immunotherapy gets more exciting every year,” said ASCO expert Lynn Schuchter, MD, FASCO. “With these trials, we’re rapidly moving past the era in which immunotherapies are seen as breakthroughs for melanoma alone. Remarkably, these drugs are proving effective in other cancers where practically no other treatments work. Just as important, it’s possible that we’ll be able to pinpoint, in advance, which patients are the best candidates for these therapies.”
Pembrolizumab for Head and Neck Cancer
Results from a phase I clinical trial suggest that PD-1 immunotherapy may fill a large unmet need for better treatments for recurrent and advanced head and neck cancer. In this study, one in four (25%) participants had tumors that noticeably shrank after taking pembrolizumab. Overall, more than half (57%) of participants experienced some decrease in their tumor’s size.
Nivolumab for Liver Cancer
In another early-stage study, 42 participants with advanced hepatocellular carcinoma (HCC) received nivolumab. This treatment stopped tumors from growing for 48% of the participants. Overall, eight people had tumors that shrank by more than 30%, and two had complete remissions. A remission is when cancer cannot be detected in the body and there are no symptoms. These benefits helped 62% of the participants live at least one year after starting treatment.
Nivolumab for Lung Cancer
Earlier this year, the FDA approved nivolumab as a treatment for advanced squamous non-small cell lung cancer (NSCLC). In a recent phase III clinical trial, researchers showed that nivolumab is also an effective treatment option for people with non-squamous NSCLC. More than 580 people with advanced non-squamous NSCLC that grew or spread after receiving platinum-based chemotherapy received either nivolumab or docetaxel (Docefrez, Taxotere) chemotherapy. The researchers found that the people in the nivolumab group lived an average of three months longer than those in the docetaxel group (one year versus nine months).
Benefitting from Treatment
Unfortunately, not every tumor responds to immunotherapy in the same way. So, while immunotherapy is often the best treatment option available, it isn’t equally effective for everyone. For example, results from a small phase II study show that pembrolizumab works better when tumors have a large number of genetic changes or mutations. Researchers have also found that the protein PD-L1 helps predict which tumors are more likely to respond to treatment with a PD-1 inhibitor.
More research is needed to figure out who will benefit the most from PD-1 inhibitors. However, scientists and doctors continue to be optimistic about the future of immunotherapy.