PT - JOURNAL ARTICLE AU - David R. Colnot AU - Abraham J. Wilhelm AU - Jacqueline Cloos AU - Jan C. Roos AU - Remco de Bree AU - Jasper J. Quak AU - Gordon B. Snow AU - Guus A.M.S. van Dongen TI - Evaluation of Limited Blood Sampling in a Preceding <sup>99m</sup>Tc-Labeled Diagnostic Study to Predict the Pharmacokinetics and Myelotoxicity of <sup>186</sup>Re-cMAb U36 Radioimmunotherapy DP - 2001 Sep 01 TA - Journal of Nuclear Medicine PG - 1364--1367 VI - 42 IP - 9 4099 - http://jnm.snmjournals.org/content/42/9/1364.short 4100 - http://jnm.snmjournals.org/content/42/9/1364.full SO - J Nucl Med2001 Sep 01; 42 AB - 186Re-labeled chimeric monoclonal antibody U36 (cMAb U36) was recently evaluated in a phase I dose escalation study in head and neck cancer patients. All 13 patients received 99mTc-labeled cMAb U36 before 186Re-cMAb U36 radioimmunotherapy. The aim of this study was to evaluate the suitability of multiple or limited blood sampling to predict clearance, red marrow absorbed dose, and myelotoxicity of 186Re-cMAb U36. Methods: Population pharmacokinetics of 186Re-cMAb U36 were analyzed with a nonparametric expectation algorithm (NPEM 2) and used for Bayesian analysis of individual patient data to predict cMAb U36 clearance. Results: 186Re-cMAb U36 clearance was most accurately predicted (r = 0.91, P &lt; 0.001) with limited sampling for sample points 4 and 72 h after administration of 186Re-cMAb U36. These predictions were less accurate with 99mTc-cMAb U36 (r = 0.51, P = 0.078 for multiple sampling; r = 0.47, P = 0.104 for sampling at 4 and 21 h after administration). Thrombocytopenia was found to be correlated with the red marrow absorbed dose and was equally well predicted by limited blood sampling after administration of 99mTc-cMAb U36 (r = 0.81, P &lt; 0.01) or 186Re-cMAb U36 (r = 0.79, P &lt; 0.01). Conclusion: Limited sampling seems useful to predict pharmacokinetics and myelotoxicity of 186Re-cMAb U36.