The puzzling clinical presentation of fluoropyrimidines cardiotoxicity

Review of the fluoropyrimidine antidote uridine triacetate

In 2015, the United States Food and Drug Administration (FDA) approved uridine triacetate to treat overdose and severe toxicity of the fluoropyrimidine chemotherapy agents 5-fluorouracil (5-FU) and its oral prodrug capecitabine. Uridine triacetate is as an oral prodrug of uridine that competes with cytotoxic fluoropyrimidine metabolites for incorporation into nucleotides. Two million people worldwide start fluoropyrimidine chemotherapy each year, with 20-30% developing severe or life-threatening adverse effects, often attributable to a genetic predisposition such as dihydropyrimidine dehydrogenase deficiency. Whilst genetic prescreening is recommended prior to starting fluoropyrimidine agents, this only prevents 20-30% of early-onset life-threatening toxicity and so does not obviate the need for an antidote. Initial in-human studies established that uridine triacetate more than doubles the maximum tolerated weekly 5-FU bolus dose. A lack of clinical equipoise meant a placebo-controlled phase III trial was not ethical and so the phase III trials used historical controls. These found that uridine triacetate improved survival in those with fluoropyrimidine overdose and severe toxicity from 16% to 94%, with 34% able to resume chemotherapy within 30 days. Five case reports of delayed fluoropyrimidine toxicity demonstrate improvement following uridine triacetate treatment 120-504 h after last fluoropyrimidine administration, suggesting efficacy beyond the FDA licencing indications. Mechanistically uridine triacetate would be expected to be effective for overdose and severe toxicity of tegafur (a 5-FU prodrug), but there are no published case reports describing this. Uridine triacetate is available internationally through an expanded access scheme and has been available in the UK since 2019 on a named patient basis.

Adverse drug events associated with fluorouracil use in patients with metastatic colorectal cancer: a real-world pharmacovigilance study based on the FDA adverse event reporting system

BACKGROUND

Fluorouracil (5-FU) is widely used to treat metastatic colorectal cancer (mCRC), but real-world safety data is limited. Our study aimed to evaluate 5-FU's safety profile in a large mCRC population using the FAERS database.

RESEARCH DESIGN AND METHODS

We conducted disproportionality analyses to identify adverse drug events associated with 5-FU use in mCRC patients from 2004 to 2023. Subgroup analyses, gender difference analyses, and logistic regression were also performed.

RESULTS

We identified 1,458 reports with 5-FU as the primary suspected drug, with males accounting for 48.8% of reports. Gastrointestinal disorders were the most common adverse event (864 cases), while pregnancy-related conditions showed the strongest signal intensity (ROR = 2.97). We found 19 preferred terms with positive signals, including ischemic hepatitis (ROR = 59.32), blood iron increased (ROR = 59.32), and stress cardiomyopathy (ROR = 51.94). Males were more susceptible to weight loss and skin toxicity. Most adverse events occurred within the first month of 5-FU administration.

CONCLUSION

Our study provides a comprehensive analysis of 5-FU's safety profile in mCRC patients, helping healthcare professionals mitigate risks in clinical practice.