New Drugs Unleash Immune System to Attack Tumors
Lung, Skin, Kidney Tumors Shrink in Early-Stage Trials
June 4, 2012 (Chicago) -- Two experimental drugs that recharge the body's immune system to seek out and attack tumors are showing promise for the treatment of certain advanced lung, skin, and kidney cancers.
The drugs disable a molecular shield that tumors put up to block attacks from the immune system. In early-stage studies, the drugs shrank tumors in some people with certain types of lung, skin, and kidney cancers who had not been helped by other treatments.
Researcher Julie Brahmer, MD, associate professor of oncology at Johns Hopkins Kimmel Cancer Center, tells WebMD that she is optimistic because "in some patients, tumors did not grow back even after treatment was stopped."
"These patients had been through several types of therapy and were very ill," she says.
It's too soon to say whether the drugs will extend lives and whether they are safe in the long run. A larger, longer study is planned to test that.
But the early studies suggest the drugs work at least as well as chemotherapy drugs currently in use, and possibly with fewer side effects, Brahmer says.
The research was presented here at the annual meeting of the American Society of Clinical Oncology and published online by the New England Journal of Medicine. Both drugs are made by Bristol-Myers Squibb, which helped fund the work.
Immune Drugs: How They Work
One of the new drugs blocks a protein called programmed death-1 (PD-1) that sits on the surface of immune cells. The other drug blocks a protein called programmed death ligand-1 (PD-L1) that is on the surface of cancer cells. When PD-1 and PD-L1 join together, they form a biochemical shield that protects tumor cells from the immune system.
"We showed that blocking either of these proteins works to get tumor shrinkage," Brahmer says.
The PD-1-blocking drug was tested in about 250 patients with various advanced cancers who had not responded to standard therapies. Tumors shrank by 50% or more in 14 of 76 (18%) non-small-cell lung cancer patients, 26 of 94 (28%) patients with the potentially deadly skin cancer melanoma, and nine of 33 (27%) kidney cancer patients.
However, people in the study with prostate and colon cancer were not helped by the drug.
About 14% of patients experienced serious side effects that often required hospitalization, and three patients (1%) died from inflammation of the lung. Brahmer says that the researchers are learning how to better identify and treat people at risk for serious side effects.
Moreover, "compared with chemotherapy, which is the mainstay for most of our patients, there were fewer side effects -- no hair loss, no serious nausea and vomiting, and they were not as prone to infections," Brahmer says. Other less severe side effects included fatigue, itching, and rash.