Added to platinum-based chemotherapy, cetuximab improves lung cancer survival

August 11, 2008

Of more than 4,000 cancer studies presented at the recent annual meeting of the American Society of Clinical Oncology, those exploring effects of targeted therapy cetuximab combined with platinum-based chemotherapy generated the most buzz.

Of more than 4,000 cancer studies presented at the recent annual meeting of the American Society of Clinical Oncology, those exploring the effects of targeted therapy cetuximab (Erbitux, ImClone) combined with platinum-based chemotherapy generated the most buzz.

The reason? For the first time the targeted drug-cetuximab together with cisplatin/vinorelbine-improved survival over chemotherapy alone as first-line treatment for advanced non-small cell lung cancer (NSCLC).

NSCLC is the top U.S. cause of cancer death, expected to kill about 170,000 men and women this year.

At the ASCO meeting, more than 80 studies evaluated the potential of adding cetuximab to standard chemotherapy in advanced NSCLC.

"NSCLC is the most common type of lung cancer, comprising 85% to 90% of all cases," Robert Pirker, M.D., an associate professor of medicine at Medical University of Vienna (Austria), said. "More than 80% of NCSLC patients have tumors that express the EGFr gene."

Only about 30% of those with very advanced disease survive one year after diagnosis, while about 1% to 2% survive five years, he said.

Residing on the surface of these tumor cells, EGFr is activated when naturally occurring proteins in the body bind to it, Pirker said. This binding changes the shape of EGFr, which, in turn, triggers internal cellular signals that enhance tumor cell growth.

"The results of our randomized study, involving 125 advanced NSCLC patients from 30 countries, clearly establish cetuximab plus chemotherapy as a new standard in first-line treatment," Pirker said.

The study compared the effects of adding or not adding cetuximab to standard platinum-based chemotherapy (cisplatin and vinorelbine) plus a "third-generation drug" such as paclitaxel or gemcitabine (Gemzar, Eli Lilly). Virtually every patient had Stage 4 disease.

"Overall survival was greater (11.3 months) for patients who received cetuximab plus chemotherapy than for those on chemotherapy alone (10.1 months)," he said. "Also, the patients in the combined treatment arm had a better response rate (36.3%) than those on chemotherapy alone (29.2%)."

An acne-like rash was the most frequent side effect.

KRAS gene predicts colorectal response

In related treatment news, researchers presented data showing that, when cetuximab was added to standard chemotherapy, patients whose metastatic colorectal tumors expressed the normal KRAS gene had a better clinical response than colorectal cancer patients with KRAS mutations in their tumors.

KRAS is the first molecular marker for the selection of a targeted therapy plus a standard chemotherapy regimen in metastatic colon cancer. It was notably effective in predicting response to treatment when cetuximab was combined with FOLFIRI (a regimen of fluorouracil, leucovorin, and irinotecan), according to the researchers.

"Our new biomarker analysis showed that cetuximab worked in the 60% of patients whose tumors harbored normal KRAS but not in the other 40% with KRAS mutations," lead investigator Eric van Cutsem, M.D., Ph.D., professor at the University Hospital Gasthuisberg in Leuven, Belgium, said.

Doctors and pharmacists should know cetuximab will not work in colorectal cancer patients with KRAS mutations but will work in the 60% of patients with normal-i.e., non-mutant KRAS, he stressed. Thus, testing should be routinely conducted in all colorectal cancer patients starting immediately after diagnosis so that the best treatment strategies can be planned for each individual.

In the first-line treatment setting, among patients with normal KRAS, 59.3% responded dramatically to a combination of chemotherapy and cetuximab (their tumors shrank by more than half), while 43.2% responded to chemotherapy alone, the researchers said.

THE AUTHOR is a writer based in New York.