NEW YORK (Reuters) - An experimental drug being developed by Pfizer Inc that targets a specific gene mutation demonstrated impressive anti-tumor activity in patients with advanced non-small cell lung cancer (NSCLC), according to data from a small study presented on Saturday.
More than half of the patients treated with the drug, crizotinib, experienced significant tumor shrinkage, and nearly 90 percent had at least some positive response, such as a smaller degree of tumor shrinkage or no worsening of the disease.
"Many of these patients had received three or more prior treatments, and we would expect only about 10 percent to respond. That is why we are so excited about the results," said Dr Yung-Jue Bang, the study's lead investigator, who presented the data at the American Society of Clinical Oncology meeting in Chicago.
"These results are quite dramatic, and represent an important improvement over what we would see with standard chemotherapy for patients with metastatic disease," added Bang, professor in the Department of Internal Medicine at Seoul National University College of Medicine in South Korea.
Researchers had speculated that the fusing of a gene known as ALK with another gene called EML4 might help explain the incidence of lung cancer in nonsmokers.
About one in 20 lung cancer patients in the United States are estimated each year to be diagnosed with ALK-positive NSCLC, researchers said. Pfizer estimates there are about 7,500 to 10,000 patients in the United States with the gene mutation.
Crizotinib, which is taken orally twice a day, works by inhibiting the ALK enzyme that is critical for the growth and development of cancer cells.
All of the 76 treated patients in the open label study had the gene mutation and were either nonsmokers or had long given up smoking. Most had already undergone multiple chemotherapy regimens, researchers said.
Fifty-seven percent of the treated patients had their tumors shrink at least 30 percent, which was characterized as a partial response.
But 87 percent experienced at least some tumor shrinkage or stable disease after eight weeks, researchers said.
One patient had a complete response with total disappearance of the tumor. Another three or four had no measurable tumor, but could not be characterized as a complete response because of some residual abnormality, such as scarring, Pfizer said.
A reduction in tumor-related symptoms, such as severe shortness of breath, coughing, and severe pain was also seen with crizotinib treatment.
"We have seen a number of patients whose symptoms begin to improve within days or weeks of starting therapy," said Mace Rothenberg, Pfizer oncology's senior vice president for clinical development and medical affairs.
Crizotinib is already being tested in a late-stage study against second-line chemotherapy agents. The drug is being developed in conjunction with a diagnostic test from Abbott Laboratories to detect the ALK gene mutation, marking another potential step forward in the field of personalized medicine.
The most common side effects were nausea and vomiting and were considered to be relatively mild.
The median duration of treatment was about six months -- another encouraging sign as the prognosis for recurrent lung cancer patients is typically survival of just three or four months.
There was no available median progression-free survival data, meaning more than half the patients in the study were still alive at the time of analysis.
(Reporting by Bill Berkrot, editing by Matthew Lewis)
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