"Individuals who are homozygous for the UGT1AI*28 allele are at increased risk for neutropenia following initiation of Camptosar treatment. A reduced initial dose should be consider for patients known to be homozygous for the UGT1A1*28 allele (see Dosage and Administration). Heterozygous patients (carriers of one variant allele and one wildtype allele which results in intermediate UGT1A1 activity) may be at increased risk for neutropenia; however clinical results have been variable and such patients have been shown to tolerate normal starting doses."
Source [pfizer.com]
GT1A1 Molecular Assay is an accredited test (ISO17025 – Belac) that detect a genetic polymorphism in the UGT1A1 gene promotot. The enzyme produced by UGT1A1 is responsible for the metabolism of irinotecan (Camptosar®), a drug used in combination with standard chemotherapeutic agents in the first-line treatment of patients with metastatic colorectal cancer.
The active form of irinotecan is metabolized by the polymorphic enzyme UGT1A1. UGT1A1 activity is reduced in individuals with UGT1A1*28 and *37 genetic polymorphism and increased in individuals with UGT1A1*36 genetic polymorphism. Approximately 10% of the North American population is homozygous for the UGT1A1*28 allele while other mutants are very rare. Patients with reduced UGT1A1 activity are at an increased risk of experiencing grade 4 neutropenia when treated with irinotecan.
Our Belac accredited assay detects the *1 (TA6), *28 (TA7), *36 (TA5) and *37 (TA8) alleles of the UGT1A1 gene in genomic DNA. This test will help identify patients with a greater risk for irinotecan toxicity.
These drugs have an information regarding importance of genetic variability contained in product labeling. We provide pharmacogenetic assays for the following drugs:
1 week
A report will be generated including mutations that have been detected and in the case of mutants, the inferred metabolism status.
Please inquire for ordering information.