Saturday, June 2, 2012

Immune therapy may yield long-lasting treatment for many cancers

When cancers are diagnosed after they've spread, even the most advanced treatments often provide only weeks or months of control until cancerous cells start growing again. But a new class of immune enhancing drugs appears capable of longer lasting suppression -- possibly years -- for people with late-stage lung cancer and other difficult-to-treat tumors. 

"There is still a long road ahead, but now it's lined with some successes," says Dr. Walter Urba, an immune therapy expert at the Providence Cancer Center in Portland, which recently joined an international clinical trial network funded by Bristol-Myers Squibb Co. to study targeted immune therapies.

A related treatment, anti-PD-L1, shrank or eliminated tumors in 6 to 17 percent of about 200 patients with advanced kidney cancer, lung cancer, melanoma, or ovarian cancer. Suppression lasted for at least a year in 8 of the 16 patients who enrolled in the study early enough to follow for 12 months. 

The suppression of lung cancer particularly surprised researchers because of the lack of effect of previous immune-directed treatments against that cancer. In a disappointing surprise, the treatments didn't work in people with colon cancer or pancreatic cancer. Researchers are reporting the results today in the New England Journal of Medicine and at the meeting of the American Society of Clinical Oncology. 

Both treatments are engineered antibodies, given as a series of injections that unleash the body's natural immune defenses. Tumors often evade immune attack by sending signals that ward off killer T-cells. The engineered antibodies target key checkpoints in the signaling chain, allowing T cells to continue attacking cancer tissue.