Regimen selection for first-line FOLFIRI and FOLFOX based on UGT1A1 genotype and physical background is feasible in Japanese patients with advanced colorectal cancer.

OBJECTIVE We examined the feasibility of regimen selection for first-line irinotecan, 5-fluorouracil and leucovorin or oxaliplatin, 5-fluorouracil and leucovorin in Japanese patients with advanced colorectal cancer based on UDP-glucuronosyltransferase 1A1 genotype as well as physical status of patients related to diarrhea. METHODS As first-line irinotecan, 5-fluorouracil and leucovorin is a little bit superior to oxaliplatin, 5-fluorouracil and leucovorin with respect to efficacy and toxicity, patients without risk factors of irinotecan-induced toxicity were first assigned to irinotecan, 5-fluorouracil and leucovorin. Patients with UDP-glucuronosyltransferase 1A1 28/ 28, 6/ 6, 28/ 6 or 28/ 27 and those with ascites, peritoneal dissemination or diarrhea first received oxaliplatin, 5-fluorouracil and leucovorin to avoid the irinotecan-induced neutropenia and diarrhea, respectively. We retrospectively evaluated the feasibility of this strategy by assessing toxicity and total progression-free survival in first- and subsequent second-line therapies in all patients studied. RESULTS In the first-line irinotecan, 5-fluorouracil and leucovorin (n = 61), Grade 4 neutropenia, febrile neutropenia and Grade 3 diarrhea occurred in 8.2, 3.3 and 3.3% of patients, respectively. In the first-line oxaliplatin, 5-fluorouracil and leucovorin (n = 26), Grade 4 neutropenia, febrile neutropenia, Grade 3 thrombocytopenia and Grade 3 neuropathy were observed in 11.5, 3.8, 3.8 and 7.7% of patients, respectively. In the second-line oxaliplatin, 5-fluorouracil and leucovorin (n = 38), Grade 3 diarrhea occurred in 2.6% of patients. In the second-line irinotecan monotherapy (n = 11), Grade 4 or febrile neutropenia occurred in 18% of patients and Grade 3 diarrhea in 9.1% of patients. In second-line S-1 (n = 9), Grade 3 anemia occurred in 2 patients. Median total progression-free survival in all 87 patients was 11.5 months. CONCLUSIONS Present regimen selection strategy would be feasible, since it causes less toxicity and similar efficacy comparing to previous studies. Determination of appropriate reduced dose in the second-line irinotecan monotherapy or other standard second-line therapy for patients with high-risk to irinotecan-induced toxicity might make this strategy more effective.