Laboratory Corporation of America this week said it had launched a UGT1A1 test to support treatment with Pfizer's colorectal cancer drug Camptosar.
The reference lab is now easily the largest entity to offer the test, which identifies patients at risk for developing adverse reactions to the drug, joining a market populated only by Mayo Medical Laboratories and Genzyme. "In terms of geographic region access nationally to physicians, doctors' groups, and other candidates who order the tests, certainly we have a very far-reaching [organization] — we have a land/air courier network, whereas other laboratories don't have that setup," a LabCorp spokesperson told Pharmacogenomics Reporter this week.
LabCorp's and Genzyme's tests are based on the same intellectual property. Mayo Medical Laboratories, the reference laboratory associated with the Mayo Clinic, has an exclusive license to the UGT1A1 technology through an agreement with the University of Chicago Hospital, which it sublicensed to Third Wave Technologies and to LabCorp. Third Wave sells its UGT1A1 test through Genzyme, which, like Mayo Medical Laboratories and LabCorp, offers its CLIA laboratory services directly to hospitals and clinicians.
Asked whether LabCorp has received many requests for UGT1A1 testing, the company's spokesperson said, "I think the reason we added [the test to the company's product menu] is because we recognized that it's a test that can have real value for physicians."
Sales of Camptosar, whose generic name is irinotecan, may prove to be a useful estimation of the upper limit of the annual market for a UGT1A1 test. According to unaudited financial reports from Pfizer, Camptosar generated $910 million in revenue last year, a 64-percent increase year over year. Sales in the United States amounted to $471 million for 2005, versus $449 million for the similar period during the previous year.
According to the American Cancer Society, colorectal cancer is the third most commonly diagnosed cancer and the second most common cause of cancer death in the United States, with approximately 145,290 new cases expected to have been diagnosed last year.
The UGT1A1-testing market has appeared almost overnight. Genzyme only began offering Third Wave's UGT1A1 colon cancer solid-tumor test in North America in early December, and Mayo began offering its test later that month. Prior to December, the test based on intellectual property from the University of Chicago was only available to patients through studies performed there.
The FDA changed Camptosar's label in June to encourage companies to develop and submit their own UGT1A1 assays, but the only FDA-cleared diagnostic for detecting UGT1A1 genotype so far is the test Third Wave offers on its Invader platform. CLIA laboratories do not have to use FDA-cleared devices, although clearance can raise the status of a test in the eyes of customers. The newer Camptosar label recommends a lower starting dose of the drug in patients homozygous for the UGT1A1*28 allele.
Camptosar is metabolized by the enzyme product of the gene UGT1A1, a variation of which confers a five-fold greater risk of adverse events, according research conducted by the US Food and Drug Administration. Adverse events can include neutropenia, an immune-system disorder, according to the drug's label. Other events include severe diarrhea.
— Chris Womack ([email protected])