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 measure ment of paclitaxel and related taxanes in crude extracts of Taxus sp., in h uman serum and in culture medium of paclitaxel-producing microorganisms suc h as Erwinia taxi. For the ELISA, paclitaxel was chemically modified by the introduction of an amine to enable coupling with biotin. The presence of p aclitaxel or related taxanes competitively inhibited the binding of paclita xel-biotin to anti-taxane monoclonal antibody. This method detected paclita xel in concentrations as low as 33 pM; the affinity of the antibody was hig her for paclitaxel than for cephalomanine, baccatin and DAB. The sensitivit y of this assay makes ii useful for estimating the paclitaxel and taxanes c ontent of Taxus sp. extracts, monitoring the paclitaxel serum level of pacl itaxel treated patients and in other biological fluids.