Association of Capecitabine Pharmacokinetics and Toxicity With Aging

A Prospective Evaluation of Capecitabine and Metabolite Pharmacokinetics in Elderly Breast and Colorectal Cancer Patients and Their Association With Toxicity and Molecular Markers of Enzyme Activity and Aging

This is a multi-centre prospective non-interventional study designed to evaluate the effects of patient age on the pharmacokinetics of capecitabine and its metabolites 5'DFCR, 5'DFUR, and 5-FU. In addition, the study will assess the correlation between the pharmacokinetic parameters calculated and cytidine deaminase, biomarkers of aging, clinical frailty, treatment outcome, and toxicity. To be enrolled, patients must have breast or colorectal cancer and be eligible to receive capecitabine monotherapy in accordance with its approved clinical usage in the UK. Treatment will be administered according to NICE guidelines as well as the clinical judgement of the prescribing physician. One hundred patients (50 breast cancer patients, 50 colorectal cancer patients) who are about to start treatment with capecitabine monotherapy will be recruited to the study and undergo study procedures within the first week of treatment.

Inclusion Criteria:

• 1) Histologic or cytologic diagnosis of breast cancer or colorectal cancer. Patients should have disease that is suitable for capecitabine monotherapy as defined by the NICE Guidelines.

  2) Patients must be within the first week of their first cycle of capecitabine treatment.

  3) Estimated life expectancy of greater than 3 months. 4) Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2. 5) Total serum bilirubin less than or equal to 25 micromol/L. 6) Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels less than 2.5 times the upper limit of the normal range.

  7) Serum albumin level greater than 32 g/L. 8) Creatinine clearance greater than or equal to 30 mL/minute. 9) Blood haemoglobin level of greater than 9 g/dL, with transfusion allowed. 10) Absolute neutrophil count greater than 2.5 x 109/L. 11) Platelet count greater than 100 x 109/L. 12) 18 years of age or older. 13) Written informed consent.

Exclusion Criteria:

1. Pregnancy or breast feeding.

2. Known HIV, Hepatitis B, or Hepatitis C infection.

3. Known Gilbert syndrome.

4. Uncontrolled diabetes (HbA1c greater than 7.5%).

5. Any condition or disease that might affect oral absorption of medications, including:

   1. Crohn's disease

   2. Ulcerative colitis

   3. Major gastric or small bowel resection

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