Development of a very sensitive luminescence assay for the measurement of paclitaxel and related taxanes.

A rapid and very sensitive enzyme immunoassay was developed for the measurement of paclitaxel and related taxanes in crude extracts of Taxus sp., in human serum and in culture medium of paclitaxel-producing microorganisms such as Erwinia taxi. For the ELISA, paclitaxel was chemically modified by the introduction of an amine to enable coupling with biotin. The presence of paclitaxel or related taxanes competitively inhibited the binding of paclitaxel-biotin to anti-taxane monoclonal antibody. This method detected paclitaxel in concentrations as low as 33 pM; the affinity of the antibody was higher for paclitaxel than for cephalomanine, baccatin and DAB. The sensitivity of this assay makes it useful for estimating the paclitaxel and taxanes content of Taxus sp. extracts, monitoring the paclitaxel serum level of paclitaxel treated patients and in other biological fluids.