Study of Genetic Polymorphisms of Drug Transporters and Orphan Nuclear Receptors on Treatment Effects of Irinotecan

• SLCO1B1 and PXR genotypes and maximal response rate [ Time Frame: Before & during treatment ]
  
• SLCO1B1 and PXR genotypes and pharmacokinetics of SN-38 [ Time Frame: Before and 1st cycle ]
  

• SLCO1B1 and PXR genotypes and response duration, time to progression and overall survival
  

For the genotype-PD association, 50 colorectal cancer patients treated with FOLFIRI will be enrolled and studied. 50 additional colorectal patients treated with any kind of irinotecan containing regimen will be enrolled and including the 50 patients for the genotype-PD association, a total of 100 patients will be evaluated for the genotype-PK association.

Blood samples for PK analysis will be collected from patients with colorectal cancer during 1st treatment cycle of irinotecan and 2nd, 3rd infusion. During the 1st treatment cycle, blood will be drawn 0 h (before irinotecan infusion), 0.75 h, 1.5 h and each at time ranges of 2~8 h, 8~16 h, 24~32h and 48~52 hours after the start of irinotecan infusion over 90 min and additional blood will be collected 48~52 hours after the respective 2nd and 3rd infusion.

For 50 colorectal cancer patient treated with FOLFIRI regimen, responses to the treatment will be assessed every 3 cycles. All assessments will be repeated at the end of trial therapy.

The RECIST criteria for measurable disease will be followed and toxicity will be evaluated according to NCI common toxicity criteria version 3.0.

Time to disease progression will be calculated from the date of study entry to the first objective documentation of progressive disease. Response duration will be measured from the date a patient first fulfills the CR or PR criteria to the first date of objective documentation of disease progression.