June 7, 2010 (Chicago) -- An experimental pill shrank tumors in lung cancer patients who have a specific genetic abnormality.
After treatment with the drug crizotinib, tumors shrank or stopped growing in more than 90% of 82 advanced lungcancer patients with the genetic abnormality. In 57%, tumors shrank by 30% or more. Side effects were generally mild.
"That's huge for a population of lung cancer patients where most treatments have only a 10% response (tumor shrinkage) rate, with considerable toxicity," says Indiana University's George W. Sledge Jr., MD, incoming president of American Society of Clinical Oncology (ASCO).
It’s too early to know if the drug actually extends lives. And only the 4% of lung cancer patients worldwide with the gene abnormality targeted by the drug are typically helped by crizotinib.
Still, that translates to more than 8,000 people in the U.S. each year, Sledge tells WebMD.
The findings were presented at ASCO's annual meeting.
Crizotinib blocks an aberrant protein called ALK that is critical for the growth and survival of cancer cells.
In some people, an aberration causes the ALK gene to fuse with another gene, typically EML4 in lung cancer.
This, in turn, inappropriately turns on the ALK gene so it produces more and more of the ALK protein, driving tumor growth.
No one knows exactly why it happens, but lung cancer patients with the abnormality are generally nonsmokers. And they're typically younger, in their 50s on average. The abnormality is not inherited.
It's easy to test for ALK aberration, "so we can tell right away if you’re likely to respond to the drug," says Roy Herbst, MD, chief of thoracic medical oncology at the University of Texas M.D. Anderson Cancer Center in Houston. He was not involved with the work.
Only 28% Chance of Lung Cancer Progression
People in the study had advanced non-small-cell lung cancer (NSCLC), the most common type of cancer. In many cases, the disease had already spread to other parts other body. They had failed to respond to an average of three, and up to seven, drugs.
Most were former light smokers or never-smokers, and all had the ALKgene fusion.
After an average of six months of treatment, there was only a 28% chance that the cancer got worse, and responses to crizotinib have lasted for up to 15 months, says one of the study's leaders, Yung-Jue Bang, MD, of the Seoul National University College of Medicine in South Korea.
About 50% of patients on crizotinib had mild diarrhea or nausea that generally occurred early on and resolved after a few weeks. Ten percent had elevated liver enzymes that sometimes required stopping treatment, usually temporarily.