An important source of clinical data that could have propelled the development of ImClone Systems Inc.'s star drug Erbitux evaporated even as the company reported a wider first quarter loss.

Germany's Merck KGaA rejected ImClone's request to increase the number of patients in its trial of cancer drug Erbitux. ImClone asked for the modification so it would have more data to minimize the delay in filing its next application to gain Food and Drug Administration approval of the drug. Last year, the FDA rejected ImClone's Erbitux application but earlier this year said it would consider data from the European trial when it re-examines the drug.

Merck owns the European rights to Erbitux, and still will give ImClone the data from its 300-person trial. It just won't increase the trial to include 500 people as ImClone had requested.

"Our study is designed for our area of responsibility, which is Europe," said Merck spokesman Hartmut Vennen. "That is what our contract says."

Neither ImClone nor Bristol-Myers Squibb Co. immediately returned calls for comment. Last year, Bristol agreed to pay US$ 2 billion for 20 percent of ImClone and 40 percent of Erbitux's revenues. The deal has since been modified.

Revenues fell 34 percent to US$ 18.6 million during the first quarter from US$ 28 million last year. Revenues for first quarter of 2001 included a US$ 24 million milestone payment from Merck.