Saturation of Mylotarg present in patient serum to monocytes in vitro.

Purified monocytes from healthy controls were incubated with patient serum obtained just before the start of the first (hatched bars) or second (open bars) Mylotarg treatment cycle, after which saturation was analyzed by comparing Mylotarg bound in vitro with the maximal Mylotarg binding. Patients showing more than 30% saturation in vivo at the start of the second treatment cycle (n = 7) were compared with patients showing less than 15% saturation in vivo at the start of the second treatment cycle (n = 3). Data are expressed as mean ± SD. A significant difference (P < .05; indicated by the asterisk) was observed between in vitro saturation with precycle 1 serum and in vitro saturation with precycle 2 serum in the patients with more than 30% saturation in vivo. Saturation levels less than 10% should be regarded as baseline levels.