FDA

FDA updates cancer drug labels to warn of enzyme deficiency–linked toxicity

February 6, 2026

FDA has updated safety labeling for capecitabine (Xeloda) and fluorouracil (5‑FU) to strengthen warnings about serious and potentially fatal toxicities in patients with dihydropyrimidine dehydrogenase (DPD) deficiency. Because DPD metabolizes >80% of 5‑FU, reduced or absent enzyme activity can lead to early-onset, severe adverse reactions such as mucositis, diarrhea, neutropenia, and neurotoxicity. The updated labels add a boxed warning highlighting death risk in patients with complete DPD deficiency and recommend testing for DPYD variants prior to initiating therapy unless immediate treatment is necessary. Use of capecitabine or 5‑FU should be avoided in patients with certain homozygous or compound heterozygous DPYD variants associated with complete DPD deficiency, as no safe dose is established. For partial DPD deficiency, dosing should be individualized with careful monitoring, and patients should be counseled on toxicity signs.

Source:

(2026, February 5). FDA. Safety labeling update for capecitabine and fluorouracil (5-FU) on risks associated with dihydropyrimidine dehydrogenase (DPD) deficiency. https://www.fda.gov/drugs/resources-information-approved-drugs/safety-labeling-update-capecitabine-and-fluorouracil-5-fu-risks-associated-dihydropyrimidine