Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
FOLFIRI is a chemotherapy combination of folinic acid (leucovorin), fluorouracil (5-FU) and irinotecan, given by drip every two weeks. It is used mainly for advanced bowel cancer, often with a targeted antibody such as bevacizumab or cetuximab, and sometimes for stomach and pancreatic cancers.
Two genes have strong evidence for the medicines in FOLFIRI. UGT1A1 clears SN-38, the active form of irinotecan; people with two low-activity copies (*28/*28, the Gilbert's syndrome genotype, or *6, more common in East Asian populations) are more likely to have severe neutropenia and diarrhoea. DPYD breaks down fluorouracil, and people with low-function DPYD variants keep much more of it. Guidelines exist for both genes for the individual medicines, which have their own pages.
Every published finding on gene variants and FOLFIRI Chemo Regimen. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
UGT1A1 UGT1A1*1, UGT1A1*28: Level 1A · replicated. Toxicity: Neutropenia. 33.
UGT1A1 UGT1A1*1, UGT1A1*6, UGT1A1*28: Level 1B · replicated. Toxicity: Diarrhea. 24.
UGT1A1 UGT1A1*1, UGT1A1*6: Level 1B · replicated. Toxicity: Neutropenia. 15.
TYMS rs45445694: Level 3. Efficacy: overall survival, Progression-free survival. 13.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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