What Is FOLFIRINOX Chemotherapy?

FOLFIRINOX is an acronym, not a drug. It stands for folinic acid, fluorouracil, irinotecan, and oxaliplatin. Folinic acid is usually called leucovorin.

Only three of those are chemotherapy. Leucovorin is a vitamin-derived drug. It makes fluorouracil work harder against the cancer cell. Irinotecan is a topoisomerase inhibitor. It blocks an enzyme cancer cells need in order to unwind and copy DNA. Oxaliplatin is a platinum drug that damages DNA directly.

One trial set the standard combination for pancreatic cancer: oxaliplatin, irinotecan and leucovorin, then fluorouracil twice over — once as a rapid injection, then as a 46-hour infusion. Cycles repeat every 2 weeks. Each amount is worked out for you by the chemotherapy pharmacy from your height, weight and blood results, so nobody's treatment sheet looks quite like anybody else's.

That 46-hour infusion is why people go home wearing a pump. The bag runs for roughly two days after the clinic visit, then gets disconnected.

A multicenter phase II/III trial enrolled 342 patients with metastatic pancreatic adenocarcinoma. Everyone had an ECOG performance status of 0 or 1. That means fully active, or held back only in strenuous activity. Patients were assigned at random to FOLFIRINOX or to gemcitabine.

Median overall survival was 11.1 months with FOLFIRINOX. It was 6.8 months with gemcitabine. The hazard ratio for death was 0.57, with a 95% confidence interval of 0.45 to 0.73. The p value was below .001.

Median progression-free survival was 6.4 months versus 3.3 months, with a hazard ratio of 0.47.

One result surprises people. FOLFIRINOX is the harsher regimen, yet quality of life held up better. At 6 months, 31% of the FOLFIRINOX group had a definite decline in quality of life. In the gemcitabine group it was 66%. Febrile neutropenia hit 5.4% of the FOLFIRINOX group. That means fever with a dangerously low neutrophil count.

PRODIGE-24 tested the regimen after the tumor was removed. It enrolled 493 patients with an R0 or R1 resection, meaning no visible tumor left behind. Half got 12 cycles of FOLFIRINOX. Half got 6 cycles of gemcitabine.

The version used after surgery lowers the irinotecan. The other three drugs stay as they were, still every 2 weeks, with the 46-hour fluorouracil infusion.

Median follow-up ran 69.7 months. Median disease-free survival was 21.4 months with FOLFIRINOX and 12.8 months with gemcitabine. The hazard ratio was 0.66.

Median overall survival was 53.5 months versus 35.5 months, hazard ratio 0.68. Five-year overall survival was 43.2% with FOLFIRINOX and 31.4% with gemcitabine.

The cost side is equally concrete. Grade 3 or 4 toxicity affected 75.9% of the FOLFIRINOX group against 52.9% on gemcitabine. Growth factor support with granulocyte colony-stimulating factor was given to 62.2% of the FOLFIRINOX group. And 33% stopped treatment early, compared with 21% on gemcitabine.

Modified FOLFIRINOX, written mFOLFIRINOX, drops the fluorouracil bolus, lowers irinotecan, or both. It is not a weaker second choice. It is what most current trials use.

The A021501 trial gave eight 2-week cycles of modified FOLFIRINOX before surgery. All the patients had borderline resectable pancreatic cancer. Median overall survival in that arm was 29.8 months. Clear margins under the microscope were achieved in 43%. Grade 3 or higher treatment-related events occurred in 57%.

The second arm of that trial added radiation after seven cycles. It was closed early for futility because the clear-margin rate was only 33% in the first 30 patients.

Irinotecan carries a boxed warning for diarrhea and myelosuppression, meaning low blood counts. A boxed warning is the FDA's strongest. Telling the two kinds of diarrhea apart is the most useful thing to learn before cycle one.

Early diarrhea begins during or shortly after the infusion. It often comes with cholinergic symptoms: cramping, sweating, watery eyes, runny nose. Atropine can prevent or ease it, and it is usually given in the chair.

Late diarrhea generally starts more than 24 hours after the dose. The label states plainly that it can be life threatening. It is treated promptly with loperamide, plus fluid and electrolyte replacement. Antibiotics are added for fever, for severe neutropenia, or for ileus, meaning the bowel stops moving. Severe diarrhea means pausing irinotecan and cutting the dose in later cycles.

Have loperamide in the house before the first cycle, and get written instructions on how many tablets and how often. Do not use a general over-the-counter dosing schedule for this.

Irinotecan is cleared by an enzyme encoded by the UGT1A1 gene. Some people carry versions that clear it slowly.

The label names three of them. People with the UGT1A1 *28/*28, *6/*6, or *6/*28 genotypes face a higher risk of severe neutropenia on this drug. Ask whether UGT1A1 testing is part of your workup and what the result was.

Kidney damage and acute kidney failure have occurred. It usually happens in people who got badly dehydrated from severe vomiting or diarrhea. That is one more reason dehydration is not a minor problem here.

Interstitial pulmonary disease-like events have occurred, including deaths. New or worsening shortness of breath, cough, and fever mean stopping the drug pending evaluation.

Severe allergic reactions, including anaphylaxis, have been observed and require stopping the drug.

Oxaliplatin adds a signature effect of its own. It damages nerves in the hands and feet, and cold can trigger or worsen it. Ask about cold exposure precautions before you leave the first infusion.

• Call 911 or go to an emergency department if you have swelling of the lips, tongue, or throat, hives, or sudden trouble breathing during or after an infusion. The label reports severe allergic reactions, including anaphylaxis.
• Call 911 or go to an emergency department if you are too faint or confused to stand, or you cannot breathe comfortably at rest.
• Call your oncology team's urgent line straight away, at any hour, if you have a temperature of 100.5°F (38°C) or higher — the figure NCI prints, though MedlinePlus and CDC give 100.4°F (38°C) — or shaking chills. On this regimen a fever in the low-count window is an emergency in its own right, so it is a call to make now rather than in the morning. If the line does not get you a person quickly, go to an emergency department and say you are on FOLFIRINOX.
• Call your care team the same day if diarrhea keeps going despite loperamide, or you have more than a few loose stools in a day. Dehydration from diarrhea or vomiting is what drives the kidney injury described above.
• Call your care team the same day if vomiting stops you keeping fluids down, or you are passing much less urine than usual or feel faint on standing.
• Call your care team the same day if you have new or worsening shortness of breath, or a new cough with fever. The label links these to lung inflammation that means stopping the drug pending evaluation.
• Call your care team the same day if you have belly pain and are passing no gas or stool.
• Call your care team within a day or two if numbness or tingling in the hands or feet is new or worse, or you are fumbling buttons and keys. That is the oxaliplatin nerve effect, and the dose can be adjusted before it becomes lasting.

• Is this full FOLFIRINOX or modified, and which doses
• Has UGT1A1 testing been done
• Will I get growth factor support, and starting when
• What is my exact loperamide plan, in tablets and hours
• Who do I call after hours, and at what number
• Will I have a port placed, and when
• What is the goal here: before surgery, after surgery, or for metastatic disease

That last question matters most. The same four drugs are used with different intent and different expected durations. Knowing which situation you are in tells you what the numbers above actually mean for you.

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://www.cancer.gov/about-cancer/treatment/side-effects/infection https://www.cdc.gov/cancer-preventing-infections/patients/fever.html