Modern - Blog Science Connections

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Fig. 1. Treatment-induced blast cell reduction
in the bone marrow during induction
therapy in five patients with
ANLL. Open and solid stars represent
cytoreduction rates in one patient who
received two identical courses of the
induction regimen
4 weeks after completion of the first induction
course. In one patient leukemic cell mass in the
bm was only reduced by 1.4 10glO during
induction therapy and posttreatment bm examination
still showed 60% leukemie blasts.
A second course of the identical regimen
resulted in a similar cytoreduction of 1.7 10glO
and 40 % blasts were found on posttreatment
bm examination. The cytoreduction rates of
this patient are represented by the two upper
curves in Fig. 1.
11. High Dose TdR
For three of the four patients cell kill rates of
0.17, 0.13, and 0.13 10glO per day were
measured and all three achieved bm aplasia as
documented by bm biopsy. The one patient
who was treated over aperiod of 28 days
achieved a total reduction in the leukemic bm
cell mass of 3.6 10glO and went into eR. The
fourth patient did not respond to TdR as
judged by morphologie examination of bm
aspirates and biopsies, and a total blast cell
reduction of only 0.9 10glO (0.05 10glO/d) was
found after 25 days of TdR therapy.
D. Discussion
Quantitation of chemotherapy-induced cytoreduction
by monitoring the absolute number
of leukemic cells per mm 3 bm provides a new
quantitative determinant to evaluate treatment
efficacy in acute leukemia. This parameter
complements and facilitates clinical trials
with new drugs such as high dose TdR, as the
sensitivity of leukemic cells to the applied
therapy is quantifiable in vivo and after short
periods of drug exposure, which allows one to
detect response or nonresponse at an early
stage of treatment.
For induction therapy of ANLL quantitation
of therapeutic response not only permits
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