Is camptosar affected by genetics?

Yes — the active ingredient is metabolized by a gene known to vary between individuals.

Relevant genes: UGT1A1

camptosar is affected by pharmacogenetics through the UGT1A1 gene. Your genotype for this gene can change how your body processes camptosar, which can affect both how well it works and how well you tolerate it. The strongest evidence level on this page is Strong, based on CPIC or FDA guidelines.

What's in camptosar

irinotecan affected by UGT1A1

Affected by UGT1A1 · FDA · Strong evidence

Read the full irinotecan genetics guide →

Irinotecan phenotype recommendations

Published guidance from FDA on how irinotecan should be dosed or substituted based on your UGT1A1 phenotype.

Phenotype	What it means	Recommendation	Evidence
Normal Metabolizer UGT1A1	Your body processes irinotecan at a normal rate. The standard dose should work as expected.	FDA Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	Your body breaks down irinotecan slightly slower than normal. The standard dose should work as expected.	FDA Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	Your body clears irinotecan's active form much more slowly than normal, causing it to build up and significantly raising the risk of a dangerous drop in white blood cells. A lower starting dose is recommended.	FDA Reduce starting dosage by one level and adjust based on individual patient tolerance. Monitor closely for severe neutropenia.	Strong
Indeterminate UGT1A1	The impact of your genotype on response to this drug is unknown	FDA Initiate therapy with recommended starting dose.	—
Not available UGT1A1	The impact of your genotype on response to this drug is unknown	FDA Initiate therapy with recommended starting dose.	—

Source: FDA

The gene behind the guidance

UGT1A1 UDP Glucuronosyltransferase Family 1 Member A1

UGT1A1 clears bilirubin (the molecule that builds up in jaundice) and several drugs including irinotecan and nilotinib. A variant called *28, common in people of all ancestries, reduces UGT1A1 activity. It's the cause of Gilbert's syndrome, a benign condition, but it also makes cancer patients much more susceptible to severe side effects from irinotecan-based chemotherapy.

Oncology dosing of irinotecan is often adjusted down for patients carrying two copies of the UGT1A1*28 variant.

See all drugs affected by UGT1A1 →

Browse the full drug-class: Chemotherapy agents.

Related medications

Find out how your genetics affect camptosar

This page describes the general pharmacogenetics. A Gene2Rx report analyzes your own DNA to tell you which metabolizer group you fall into, across every medication.

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Informational only — not medical advice. Pharmacogenetic guidance describes population-level patterns; your individual response depends on many factors. Never start, stop, or change a medication without talking to your prescribing clinician.