Improvement in assay sensitivity for plasma dolastatin-10 using capillary electrophoresis at elevated temperatures.
The very potent antimitotic and anticancer agent, dolastatin-10 (DOL-10), currently undergoing testing in a phase II clinical trial, has been quantitated previously in human plasma by high-performance capillary electrophoresis (HPCE). This method provides a lower limit of detection of 25 ng/ml DOL-10 from extracted patient samples. Without changes in preconcentration techniques, we report a significant improvement in the sensitivity of this method using elevated temperatures with conventional UV absorbance detection and liquid-liquid extraction which lowers the detection limit to 3 ng/ml of the drug. An elevated separation temperature of 50 degrees C was critical in achieving this 8x improvement in the detection limit. Partial validation of the method at this temperature gave excellent linearity (0-100 ng/ml; y=0.018x+0.085, r=0.993), limit of quantitation (5 ng/ml), and good overall recovery of the drug (>85%). We have applied this improved method towards the in vivo quantitation of DOL-10 in mice and in a patient receiving the drug in a phase I clinical study. From these analyses we conclude that this method is suitable for clinical studies where plasma levels of DOL-10 are > or = 5 ng/ml.
Department of Genitourinary Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
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Huie
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Wong
D000818:Animals; D000970:Antineoplastic Agents / Q000097:blood*; D047630:Depsipeptides; D019075:Electrophoresis, Capillary / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D051379:Mice; D009842:Oligopeptides / Q000097:blood*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
D000970:Antineoplastic Agents; D047630:Depsipeptides; D009842:Oligopeptides; C064570:dolastatin 10