Amgen, Abgenix Shares Soar on Drug Trial Data

SAN FRANCISCO — Two California biotechnology companies, including titan Amgen Inc., said Thursday that an experimental drug they were co-developing to combat colon cancer worked better than expected during a large human trial.

The announcement sent the stock prices of Amgen and its partner, Abgenix Inc., soaring while shares of rival drug maker ImClone Systems Inc. sagged.

The drug is called Panitumumab and is produced by mice genetically engineered with human genes to make molecules that help prevent the cancer from growing in patients.

It was invented by Fremont, Calif.-based Abgenix, which saw its stock soar $3.53 a share, or 38%, to $12.90.

Abgenix had sold some of its commercial rights to the drug to Thousands Oaks-based Amgen, whose stock rose $3.61 to $77.51.

The results released Thursday showed that the drug slowed the progression of the disease by 46% in those receiving the drug compared with those who didn’t in the 463-patient experiment. A skin rash was the most common side effect.

The companies had expected the disease to progress 33% slower in those receiving the drug, Amgen Executive Vice President Roger Perlmutter said.

The patients in the trial were among the sickest of colon cancer patients who had failed to improve after receiving standard chemotherapy treatments. Perlmutter said the companies would apply by the end of the year for Food and Drug Administration approval to initially treat only the sickest patients.

Panitumumab is expected to compete with ImClone’s colon cancer fighter Erbitux. ImClone’s stock fell $7.46, or 21%, to $28.65.