An evaluation of the antimitotic activity of a group of antitumoral agents was performed. Their action was first assayed on chick embryo blood forming tissue, determining its survival, mitotic index and mitotic differential count: the statistically most active compounds were demecolcin, vinblastine and cyclophosphamide.
The same compounds were also tested on the in vitro blastic transformation of human leukocytes and their incorporation of tritiated DNA and RNA precursors.
The most active compounds in this assay was 5 fluorouracil; a lesser degree of inhibition was caused by vinblastine, cyclophosphamide and mechloretamine.
The effect of a single massive dose of the same compounds in vivo was also studied determining the in vitro activity of leukocytes of such patients, removed 48 hrs after the administration.
Preliminary results show that such leukocytes lose in variable degree their phyto-responsiveness in vitro.