An equation was developed to describe the kinetics of leukemic cell destruction in bone marrow during induction chemotherapy for acute nonlymphocytic leukemia (logZ=K₁t⁴+K₂t³+K₃t²+K⁴, where Z=leukemic cell number, t=time, and K=a constant). The leukemic cell destruction curve was biphasic; phase I was the period from the initiation of a decrease in cells to the maximum velocity of the decrease, and phase II was the subsequent period to the cessation of decrease. The following parameters were established: duration and acceleration of decrease in phases I and II, maximum velocity of decrease, duration of reduction, and residual volume of leukemic cells.
1. Patients who achieved CR showed a longer duration of phases I and II, a lower acceleration of the decrease in phase II, and smaller residual leukemic cell volume than patients who did not achieve CR. there were no significant differences of parameters related to FAB classification, type of induction therapy, or the age of the patients.
2. This equation could be adapted to explain erythroblast kinetics during induction chemotherapy. There were no significant differences of the parameters with respect to the effect of induction therapy and patient age.
3. Patients with high acceleration of the decrease in phase II had a short duration of CR and survival.
The leukemic cell destruction curve was thought to be useful not only for evaluation of the effect of induction therapy, but also for establishment of post-remission chemotherapy.