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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Adenocarcinoma, Adult, Aged, Aged, 80 and over, Antibodies, Monoclonal, Antibodies, Monoclonal, Humanized, Cetuximab, Colorectal Neoplasms, Disease-Free Survival, Drug Administration Schedule, Female, Fluorouracil, Humans, Male, Middle Aged, Neoplasm Metastasis.
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Does cetuximab pharmacokinetics influence progression-free survival of metastatic colorectal cancer patients? Context: An ancillary phase II study was conducted to study interindividual variability in cetuximab pharmacokinetics and its influence on progression-free survival (PFS) in metastatic colorectal cancer patients cotreated with irinotecan and 5-fluorouracil. Ninety-six patients received cetuximab as an infusion loading dose of 400 mg/m(2) followed by weekly infusions of 250 mg/m(2). Doses of irinotecan and 5-fluorouracil were adjusted individually. Cetuximab concentrations were measured by ELISA. Compartmental pharmacokinetic parameters were estimated by a population approach, and PFS was analyzed using a Cox model. Cetuximab pharmacokinetics was best described using a two-compartment model with both first-order and saturable (zero-order) elimination. Estimated pharmacokinetic parameters (% standard error) were as follows: central volume of distribution V(1) = 2.96 L (4%), peripheral volume of distribution V(2) = 4.65 L (6%), elimination clearance CL = 0.497 L/d (4%), distribution clearance Q = 0.836 L/d (8%), and zero-order elimination rate k(0) = 8.71 mg/d (10%). Body surface area influenced V(1), V(2), and k(0). Pretreatment serum albumin influenced CL. Risk of disease progression decreased with cetuximab global clearance (cumulative dose/cumulative area under the concentration versus time curve; P = 0.00016). Median PFS of patients with a cetuximab residual concentration on day 14 below median value was 3.3 months as compared with 7.8 months for the other patients (P = 0.004).
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Cetuximab pharmacokinetics in colorectal cancer patients can be described using a model combining linear and nonlinear elimination rates. PFS is influenced by global clearance of cetuximab, a parameter that can be estimated using cetuximab residual concentration on day 14. Final Decision: yes