Treatment Algorithm for Homozygous or Compound Heterozygous DPYD Variant Allele Carriers With Low-Dose Capecitabine.

I DPYD i screening showed that the patient was homozygous for I DPYD i *2A; measurement of DPD activity in PBMCs of this patient indicated absence of DPD activity. Pretreatment identification of the patient homozygous for I DPYD i *2A with complete DPD deficiency saved this patient from receipt of a full fluoropyrimidine dose, which most likely would have been fatal. For patients 2 and 3, samples were collected only on C1D1, on the same time points as for patient 1, except for the latest time point (the sample 10 hours after capecitabine intake was not collected for patient 2, and the last sample was collected at 12 hours instead of at 10 hours for patient 3). For patients 2 and 3, uracil levels were increased compared with reference levels (a value of 28.7 ng/mL for patient 2 and of 35.6 ng/mL for patient 3), and both values were within the top 1% of reference values. [Extracted from the article]