By Susan Heavey
U.S. health regulators are questioning whether clinical trials proposed by ImClone Systems and Amgen Inc will be adequate to show that patients with a certain type of gene are more likely to be helped by two cancer drugs, according to documents released on Friday.
Early research has indicated that patients with the normal, so-called "wild type" of a gene known as K-ras respond far better to treatment with ImClone's Erbitux and Amgen's Vectibix than those with a mutated form of the gene.
On Tuesday, the U.S. Food and Drug Administration will seek advice from outside experts on what type of clinical trial the companies need to conduct to confirm the findings.
While eliminating patients with a mutated K-ras gene from treatment would cut sales of the drugs, the findings could be a significant advance toward so-called specialized medicine in which genetic testing can determine who is most likely to benefit from expensive drugs.
ImClone, recently acquired by Eli Lilly and Co. and Bristol-Myers Squibb Co, co-market Erbitux in the United States.
Both ImClone and Amgen have proposed retrospective testing of K-ras status from large randomized trials that have already been designed and have recruited patients or are still looking to enroll them, the FDA said in documents released ahead of Tuesday's meeting.
The drugmakers modified the ongoing studies to enroll only patients with the wild type K-ras gene, the FDA said.
Amgen has already enrolled patients in two, large ongoing studies but made changes before conducting any K-ras testing, the company said in a separate document. Results are expected next year.
Enrollment in two earlier trials for ImClone's Erbitux were halted after the K-ras finding so patients could be informed. Patients are still being sought for another ongoing trial that was put on hold, the company said.
"It is no longer feasible to conduct clinical trials in patients with MT (mutant) K-ras in their tumors," it wrote.
Amgen shares were up 0.6 percent at $57.59 on Nasdaq. Lilly shares were also up 0.6 percent, at $35.84, and Bristol was up 3.5 percent at $22.21 on the New York Stock Exchange.
The documents were posted on the agency's Website at http://www.fda.gov/ohrms/dockets/ac/08/briefing/2008-4409b1-00-FDA-index.htm
