UGT1A1 Irinotecan Toxicity

Irinotecan (Camptosar®) is used, or under evaluation, in a broad spectrum of solid tumors, and is often prescribed for treating patients with metastatic cancer of the colon or rectum, especially when 5-fluorouracil treatment has not been entirely successful. Severe toxicity (eg, grade 4 neutropenia) is commonly observed in cancer patients receiving irinotecan who carry the UGT1A1*28 allele, also called TA. This test result will provide valuable information to physicians prior to initiating or modifying treatment or supplementing treatment with additional drugs.

UGT1A1 variants have also been reported in patients with disorders of bilirubin metabolism, such as Crigler-Najjar Types I and II, as well as Gilbert syndrome. Between 80% to 100% of Caucasian patients with Gilbert syndrome are reported to have either one or two copies of UGT1A1*28. G71R (*6), a UGT1A1 variant reported in Asian patients with Gilbert syndrome, is not detected by this assay.

The current test will only test the TATA box polymorphism of the UGT1A1 gene. The other polymorphisms of this gene will not be detected.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Polymerase chain reaction (PCR); capillary electrophoresis