Quantitative Analysis of AML l-ETO Fusion Transcripts
in t(8;21) Positive AML Using Real-Time RT-PCR
MARTIN WEISSER*, CLAUDIA SCHOCH, TORSTEN HAFERLACH,
WOLFGANG HIDDEMANN, SUSANNE SCHNITTGER
Introduction
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that
requires urgent cytostatic treatment. The incidence of AML is approximately 2-4
new cases per 100,000 with a median age of about 65 years. Despite intensive
treatment with cytotoxic drugs and bone marrow transplantation, long-term survival is less than 30% [1, 2]. In AML an early progenitor is transformed to a
leukemic blast that proliferates in blood and bone marrow and suppresses normal
hematopoiesis. In about 55% of cases the leukemic blasts show cytogenetic
abnormalities that may be associated with distinct biological and clinical features. These specific cytogenetic abnormalities can be detected via laboratory
techniques like classical cytogenetics, FISH, Southern blotting or PCR. The specific karyotype of the leukemic clone is not only one of the most important prognostic factors in AML, but it also facilitates monitoring of minimal residual disease at times of cytomorphologic remission when leukemic blasts may be undetectable by light microscopy. At primary diagnosis the estimated leukemic burden
is about 10 12 malignant cells. Complete remission after chemotherapy is defined
as the return to normal bone marrow cytomorphology with less than 5% myeloid
blasts. However, in the state of cytomorphologic remission patients may still have
10 10 leukemic blasts and relapse is a common cause of treatment failure [4]. The
kinetics of leukemic regrowth and host factors like the immune response that
influence residual leukemia remain largely unknown.
One of the most frequent chromosomal aberrations in AML is the translocation t(8;21). In t(8;21) positive AML, the AMLl gene on chromosome 21 is fused
to the ETO gene on chromosome 8.The AMLl gene encodes a DNA binding factor while the function of the ETO gene remains unknown [5]. This leads to the
expression of a constant fusion transcript that can be detected by RT-PCR [6]
(Fig. 1). In all published studies t(8;21) is associated with a relatively good prognosis compared to other AMLs with normal cytogenetics or complex karyotypes. However, 10-20% of the patients still relapse after conventional
chemotherapy [7]. Using novel quantitative real-time RT-PCR techniques we
* Martin Weisser (~) (e-mail: martin.weisser@med3.med.uni-muenchen.de)
Medizinische Klinik III, Klinikum GroBhadern,
Marchioninistr. 15, 81377 Miinchen
in t(8;21) Positive AML Using Real-Time RT-PCR
MARTIN WEISSER*, CLAUDIA SCHOCH, TORSTEN HAFERLACH,
WOLFGANG HIDDEMANN, SUSANNE SCHNITTGER
Introduction
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that
requires urgent cytostatic treatment. The incidence of AML is approximately 2-4
new cases per 100,000 with a median age of about 65 years. Despite intensive
treatment with cytotoxic drugs and bone marrow transplantation, long-term survival is less than 30% [1, 2]. In AML an early progenitor is transformed to a
leukemic blast that proliferates in blood and bone marrow and suppresses normal
hematopoiesis. In about 55% of cases the leukemic blasts show cytogenetic
abnormalities that may be associated with distinct biological and clinical features. These specific cytogenetic abnormalities can be detected via laboratory
techniques like classical cytogenetics, FISH, Southern blotting or PCR. The specific karyotype of the leukemic clone is not only one of the most important prognostic factors in AML, but it also facilitates monitoring of minimal residual disease at times of cytomorphologic remission when leukemic blasts may be undetectable by light microscopy. At primary diagnosis the estimated leukemic burden
is about 10 12 malignant cells. Complete remission after chemotherapy is defined
as the return to normal bone marrow cytomorphology with less than 5% myeloid
blasts. However, in the state of cytomorphologic remission patients may still have
10 10 leukemic blasts and relapse is a common cause of treatment failure [4]. The
kinetics of leukemic regrowth and host factors like the immune response that
influence residual leukemia remain largely unknown.
One of the most frequent chromosomal aberrations in AML is the translocation t(8;21). In t(8;21) positive AML, the AMLl gene on chromosome 21 is fused
to the ETO gene on chromosome 8.The AMLl gene encodes a DNA binding factor while the function of the ETO gene remains unknown [5]. This leads to the
expression of a constant fusion transcript that can be detected by RT-PCR [6]
(Fig. 1). In all published studies t(8;21) is associated with a relatively good prognosis compared to other AMLs with normal cytogenetics or complex karyotypes. However, 10-20% of the patients still relapse after conventional
chemotherapy [7]. Using novel quantitative real-time RT-PCR techniques we
* Martin Weisser (~) (e-mail: martin.weisser@med3.med.uni-muenchen.de)
Medizinische Klinik III, Klinikum GroBhadern,
Marchioninistr. 15, 81377 Miinchen