Methods, devices, and reagents for monitoring paclitaxel concentration in plasma for pharmacokinetic-guided dosing of paclitaxel

A method for assaying paclitaxel in a liquid sample, comprising:

• (a) applying a liquid sample comprising paclitaxel to a lateral flow assay device, the device comprising
• (i) a sample receiving zone for receiving the liquid sample;
• (ii) a detection reagent zone in liquid communication with the sample receiving zone and downstream in flow direction from the sample receiving zone,
• wherein the detection reagent zone comprises a detection reagent deposited thereon,
• wherein the detection reagent is a paclitaxel antibody, or fragment or derivative thereof, that binds paclitaxel, labeled with a detectable reporting group, and
• wherein the paclitaxel antibody, or fragment or derivative thereof, has a Kon from about 104 to about 107, and a Koff from about 10−3 to about 10−7;
• and
• (iii) a capture zone in liquid communication with the detection reagent zone and downstream in flow direction from the detection reagent zone,
• wherein the capture zone comprises first and second capture reagents immobilized thereon,
• wherein the first capture reagent is a paclitaxel material capable of binding the detection reagent (test line),
• wherein the second capture reagent is an antibody capable of binding the detection reagent (control line),
• wherein the first capture reagent is positioned at a first distance downstream in flow direction from the upstream end of the capture zone,
• wherein the second capture reagent is positioned at a second distance downstream in flow direction from the upstream end of the capture zone,
• wherein the second distance is greater than the first distance, and
• wherein the ratio of the first distance to the second distance is from about 0.0 to about 0.4, when the Kon is greater than about 2.0×105 and the Koff is less than about 1.0×10−3, and
• wherein the ratio of the first distance to the second distance is from about 0.2 to about 1.0, when the Kon is greater than about 2.0×104 and the Koff is less than about 2.0×10−4;
• and
• (b) allowing the sample to flow from the sample receiving zone through the detection reagent zone to provide detection reagent with paclitaxel;
• (c) allowing the detection reagent with paclitaxel to flow through the capture zone,
• whereby the first capture reagent (test line) competes with the analyte (paclitaxel) for binding with the detection reagent, and
• whereby the second capture reagent (control line) binds excess detection reagent;
• and
• (d) observing the amount of detection reagent bound to the first capture reagent (test line) relative to the second capture reagent (control line).