Acute Leukemias - Republican Scientific Medical Library

58 Chapter 4 · Relapsed and Refractory Acute Myeloid Leukemia
transplantation (HSCT), with generation of the potent
immunologic reaction graft-vs.-leukemia (GVL) effect,
is considered the best curative strategy. However, many
patients do not have a suitable donor or are not candidates
for transplantation. Therefore, the treatment of
patients who relapse or are refractory to conventional
initial therapy is challenging. The definition of refractory
AML includes patients who fail conventional induction
chemotherapy, those with a short (less than 6–12
months) CR1 duration, and patients who have relapsed
twice or more [1]. This definition has been useful in defining
relatively uniform populations of patients for
clinical trials.
In general, younger (< 60 years) patients have initial
CR rates of 60–80% with conventional induction chemotherapy
[2–4]. Older (> 60 years) adults, representing
the majority of the AML population, have lower initial
CR rates of 40–60% [5, 6]. The rate of CR in patients
with recurrent AML with reinduction chemotherapy is
typically lower than that achieved with initial induction
therapy and most patients have a shorter duration of
CR2 compared to CR1 [7]. If a CR2 is achieved, the median
duration of remission and disease-free survival
(DFS) are generally short (