FOLFIRINOX Chemotherapy Day by Day

FOLFIRINOX is not one drug. It is four, and the name is built from their initials:

• FOL is folinic acid, also called leucovorin. It is not a chemo drug. It is a vitamin-like helper that locks fluorouracil onto its target enzyme so the chemo works harder.
• F is fluorouracil, usually written 5-FU. It jams the enzyme cells use to make thymidine, one of the DNA building blocks.
• IRIN is irinotecan. It blocks topoisomerase I, an enzyme that untangles DNA during copying. Without it, the strands break.
• OX is oxaliplatin. It is a platinum drug that cross-links DNA so it cannot be read.

The regimen was built for pancreatic adenocarcinoma and is also used in some other gut cancers. It is demanding. The trial that put it on the map only enrolled people with an ECOG performance status of 0 or 1, meaning fully active or limited only in heavy work.

One cycle is 14 days, not 21. Day 1 is the long day.

Before anything runs, you get anti-nausea medicine. Because irinotecan can trigger a cholinergic reaction during the infusion (cramping, sweating, watery eyes, runny nose, sudden diarrhea), teams often give atropine, by vein or as a small injection under the skin, either up front or the moment symptoms start. The nurse draws up the amount.

The drugs in the original regimen studied in metastatic disease were:

• Oxaliplatin, infused over about 2 hours
• Irinotecan
• Leucovorin, which sharpens the effect of the 5-FU
• 5-FU, pushed quickly through the line
• 5-FU again, running continuously over the next 46 hours

Every one of these is worked out from your height and weight by the chemotherapy pharmacy, and trimmed for blood counts and side effects, so the amounts on your own treatment sheet will not match anybody else's.

Add access time, flushes, and the pump hookup, and day 1 typically runs five to seven hours. Almost everyone gets a port or a PICC line first, because the 46-hour infusion has to run through a central vein.

The last 5-FU dose does not finish at the clinic. You leave wearing a small pump, often a balloon-type elastomeric pump in a pouch, that pushes 5-FU slowly for 46 hours. You shower with the site covered, you sleep with it, and you come back on day 3 to have it disconnected.

Know two things before you walk out. First, where the clamp is and what to do if the tubing leaks or the line pulls. Second, the phone number for the on-call service, not just the daytime clinic.

White cells usually bottom out in the second week. In the metastatic trial, 5.4 percent of people on FOLFIRINOX developed febrile neutropenia, meaning fever with a dangerously low neutrophil count. Many teams add pegfilgrastim or filgrastim, growth-factor shots that push the marrow to make neutrophils faster. In the adjuvant PRODIGE-24 trial, 62.2 percent of people on the regimen needed growth factor.

Fatigue is usually worst on days 3 to 6, then eases enough that many people feel close to normal by day 10, just in time to start again.

Irinotecan causes diarrhea in two distinct patterns, and the label treats them separately.

Early diarrhea starts during or shortly after the infusion. It is the cholinergic reaction. It is usually short-lived and responds to atropine.

Late diarrhea starts more than 24 hours after the dose and can be life threatening. The label wants loperamide (Imodium) in your house before day 1, not fetched afterward. The regimen it gives is 4 mg at the first loose stool, then 2 mg every 2 hours until you have gone 12 hours with no diarrhea. Overnight you may take 4 mg every 4 hours. Do not run these high doses past 48 hours straight, because of the risk of paralytic ileus, a stalled bowel. Go by the loperamide instructions your own team wrote for you, not by the figures above — they are the label's reference regimen, printed here so you can see why the tablets need to be in the cupboard before day 1 and why the first loose stool is the moment to start.

If diarrhea comes with fever or a very low neutrophil count, the label calls for antibiotics, not just anti-diarrheals. That is a hospital decision, so call.

Irinotecan is cleared by an enzyme called UGT1A1. Some people carry gene variants that make less of it. The label names UGT1A1*28/*28, *6/*6, and *6/*28 as genotypes with a higher risk of severe neutropenia. A blood test can check this. Ask whether your center tests before cycle 1, because a positive result can mean a lower starting irinotecan dose.

Oxaliplatin causes an unusual acute nerve effect. Cold triggers pins and needles, numbness, or an odd tight feeling in the hands, feet, around the mouth, or in the throat. Some people get a frightening sensation of throat tightness after a cold drink, without any real wheeze or stridor.

So for the first several days after each infusion: no ice in drinks, no ice cubes, no cold drinks straight from the fridge, gloves for the freezer aisle, and warm water for washing. The effect fades between cycles at first. Over many cycles a longer-lasting numbness can build up, and that is the reason oxaliplatin often gets stopped before the other three drugs do.

In metastatic pancreatic cancer, FOLFIRINOX gave a median overall survival of 11.1 months compared with 6.8 months for gemcitabine alone, and median progression-free survival of 6.4 versus 3.3 months.

After surgery, PRODIGE-24 compared 12 cycles of a modified FOLFIRINOX (the same four drugs, with a lower irinotecan amount and no rapid 5-FU push) against six cycles of gemcitabine. Median overall survival was 53.5 months versus 35.5, and 5-year survival was 43.2 percent versus 31.4 percent. The cost was real: grade 3 or 4 side effects hit 75.9 percent on FOLFIRINOX versus 52.9 percent on gemcitabine, and 33 percent stopped early.

• Call 911 or go to an emergency department if throat tightness or trouble swallowing does not ease within a few minutes, or you cannot catch your breath.
• Ring your oncology team straight away, day or night, if any fever reaches 100.4 F (38 C) while you are on treatment, or chills set your teeth chattering; if they cannot be reached fast, go to an emergency department and tell them you are on FOLFIRINOX. Do not leave it until the clinic opens. Febrile neutropenia is the reason this regimen comes with growth-factor shots, and CDC calls a fever during chemotherapy a medical emergency.
• Call your care team the same day if diarrhea is still going after 24 hours of loperamide, you pass six or more loose stools above your normal in a day, or fluids will not stay down.
• Call your care team the same day if you have passed no urine for 8 hours, or you go dizzy on standing.
• Call your care team the same day if the pump alarms, leaks, or the line works loose.

Chemotherapy, How Chemotherapy Is Given, Diarrhea During Cancer Treatment, Fever During Chemo, and Low White Blood Cells During Chemotherapy.

• https://www.cancer.gov/types/pancreatic/hp/pancreatic-treatment-pdq
• https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e518dfc6-7e93-4fee-a66c-51e1ab71c056
• https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7dc8dfb1-dec8-43b3-b2ea-05eac054b2c6
• https://www.ncbi.nlm.nih.gov/books/NBK541102/
• https://www.cdc.gov/cancer-preventing-infections/patients/fever.html