Consolidation Therapy for Acute Myeloid Leukemia: Defining a Benchmark

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in the Journal of Clinical Oncology, to patients seen in their own clinical practice.

Concentrative nucleoside transporter 3 as a prognostic indicator for favorable outcome of t(8;21)-positive acute myeloid leukemia patients after cytarabine-based chemotherapy

Although acute myeloid leukemia (AML) exhibits diverse responses to chemotherapy, patients harboring the t(8;21) translocation are part of a favorable risk group. However, the reason why this subgroup is more responsive to cytarabine-based therapy has not been elucidated. In the present study, we analyzed expression levels of cytarabine metabolism-related genes in patients diagnosed with AML with or without t(8;21) and investigated their correlation with clinical outcomes after cytarabine-based therapy. Among the 8 genes studied, expression of the concentrative nucleoside transporter 3 (CNT3) gene was significantly higher in t(8;21)-positive patients compared to the others in the test population and the validation cohort (P<0.001 in Mann-Whitney U test; P<0.002 in Pearson's correlation analysis). Additionally, in both multivariate and univariate analyses, t(8;21)-positive patients categorized in a higher CNT3 expression tertile had longer disease-free survival [hazard ratio (HR), 0.117; 95% confidence interval (CI), 0.025-0.557; P=0.008] and overall survival (HR, 0.062; 95% CI, 0.007-0.521; P=0.010) compared to t(8;21)-positive patients in a lower CNT3 expression tertile. Notably, these trends did not occur in t(8;21)-negative patients. Our results demonstrate that CNT3 expression is associated with overall favorable outcomes and is predictive of clinical outcomes in AML patients with t(8;21). This suggests that CNT3 expression can be used to optimize treatment strategies for AML patients.

High-throughput sequence analysis of the tyrosine kinome in acute myeloid leukemia

To determine whether aberrantly activated tyrosine kinases other than FLT3 and c-KIT contribute to acute myeloid leukemia (AML) pathogenesis, we used high-throughput (HT) DNA sequence ana-lysis to screen exons encoding the activation loop and juxtamembrane domains of 85 tyrosine kinase genes in 188 AML patients without FLT3 or c-KIT mutations. The screen identified 30 nonsynonymous sequence variations in 22 different kinases not previously reported in single-nucleotide polymorphism (SNP) databases. These included a novel FLT3 activating allele and a previously described activating mutation in MET (METT1010I). The majority of novel sequence variants were stably expressed in factor-dependent Ba/F3 cells. Apart from one FLT3 allele, none of the novel variants showed constitutive phosphorylation by immunoblot analysis and none transformed Ba/F3 cells to factor-independent growth. These findings indicate the majority of these alleles are not potent tyrosine kinase activators in this cellular context and that a significant proportion of nonsynonymous sequence variants identified in HT DNA sequencing screens may not have functional significance. Although some sequence variants may represent SNPs, these data are consistent with recent reports that a significant fraction of such sequence variants are "passenger" rather than "driver" alleles and underscore the importance of functional assessment of candidate disease alleles.

Prognosis and treatment outcome in patients with acute myeloid leukemia with t(8;21)(q22;q22)

Patients with acute myeloid leukemia (AML) with the t(8;21) karyotype generally have a favorable clinical course, but key prognostic factors remain poorly defined. This study was conducted to determine the prognoses and treatment outcomes of patients with AML with this unique cytogenetic change. A total of 22 patients with AML with t(8;21)(q22;q22) were studied. Various parameters were tested for their impact on disease-free survival (DFS) and overall survival (OS). Another 55 patients with AML with a normal karyotype were included for comparison of clinical outcomes. Between patients with t(8-21) and those with a normal karyotype, no significant differences were noted in DFS (median survival, 15.23 vs 12.03 mo; P=.7626) and OS (median survival, 19.17 vs 18.93 mo; P=.7543). Among t(8;21)(q22;q22) patients, no clinical parameters showed a significant impact on DFS. Univariate analysis revealed that a higher platelet count (>15.10(9)/L) at diagnosis, a low white blood cell count (index < or =20), and hematopoietic stem cell transplantation (HSCT) as postremission therapy were associated with improved OS. On multivariate analysis, HSCT as postremission therapy and white blood cell count index <20 remained good independent prognostic factors for OS. The data presented here suggest that t(8;21)(q22;q22) cytogenetic changes in patients with AML had prognostic significance similar to that in patients with a normal karyotype; patients who harbored either karyotype had parallel clinical outcomes. It is concluded that patients with AML with t(8;21)(q22;q22) would be compromised by treatment approaches that do not include HSCT as postremission therapy.

Molecular and clinical advances in core binding factor primary acute myeloid leukemia: a paradigm for translational research in malignant hematology

Clonal chromosomal abnormalities are the most important prognostic indicators in acute myeloid leukemia (AML). Recent advances in molecular biology have allowed structural and functional characterization of many of these genomic rearrangements and have provided evidence for their primary role in leukemogenesis. Two of the most prevalent cytogenetic subtypes of adult primary or de novo AML, t(8;21)(q22;q22) and inv(16)(p13q22), are characterized by disruption of the AML1(CBF alpha 2) gene at 21q22 and the CBF beta gene at 16q22, respectively. Both genes encode a subunit of core binding factor (CBF), a regulator of normal hematopoiesis. At the molecular level, t(8;21)(q22;q22) and inv(16)(p13q22) result in the creation of novel fusion genes, AML1/ETO and CBF beta/MYH11, whose structures and functions are being successfully characterized by in vitro studies and transgenic animal models. Detection of t(8;21)(q22;q22) or inv(16)(p13q22) in adult patients with primary AML is a favorable independent prognostic indicator for achievement of cure after intensive chemotherapy or bone marrow transplantation and may serve as a paradigm for risk-adapted treatment in AML. The purpose of this review is to summarize the recent advances in the molecular biology and clinical management of t(8;21)(q22;q22) and inv(16)(p13q22) primary AML, collectively referred to here as CBF AML.

Trends in mortality from leukemia in subsequent age groups

Trends in age-standardized death certification rates from leukemias in subsequent age groups were analyzed on the basis of the World Health Organization database over the period 1960-1997 in the European Union (EU) and other developed areas of the world. In the EU, the peak rate at age 0-14 was observed in 1960-1964, and the fall in mortality was over 70%, to reach 1.2/100,000 males and 0.9/100,000 females in 1995-1997. In the age group 15-44, the fall was about 40% for males and 45% for females. In the age group 45-59, the fall was around 25%. At age 60-69, the peak rate was observed in the late 1970s, and the subsequent fall was only 6% for females. At age > or =70, leukemia mortality rose up to the late 1980s, and levelled off there-after. Overall, the falls in leukemia mortality over the 35-year calendar period corresponded to the avoidance of about 7,000 deaths per year. In eastern Europe, the falls in children and young adults started later --in the late 1970s--and were less than 40% for children and 30% for young adults (15-44 years). Overall age-standardized mortality from leukemia did not appreciably change over the 35-year period considered. Leukemia mortality rates in the USA and Japan started from different values, but were similar to those of the EU in the late 1990s, indicating that the impact of therapeutic advancements has been comparable in developed areas of the world. In eastern Europe, however, the declines in leukemia mortality were later and appreciably smaller.

Trends in survival for patients diagnosed with cancer in Vaud, Switzerland, between 1974 and 1993

BACKGROUND

Analysis of trends in cancer survival in defined well surveilled populations can provide useful indications on advancements in cancer management and treatment.

PATIENTS AND METHODS

Survival rates from the Vaud Cancer Registry were computed for 31,158 cases registered in 1984-1993, and compared with those registered in 1974-1978 and 1979-1983.

RESULTS

A systematic, albeit generally moderate, tendency towards increasing five-year relative survival was observed for both sexes and most major cancer sites, including oral cavity and pharynx (0.38-0.43). stomach (0.21-0.26), colon (0.49-0.55), rectum (0.45-0.51), lung (0.08-0.12), skin melanoma (0.67-0.89), female breast (0.67-0.80), endometrium (0.72-0.84), ovary (0.28-0.37). prostate (0.44-0.66), testis (0.73-0.96), bladder (0.31-0.50), kidney and renal pelvis (0.41-0.59), thyroid (0.73-0.81), non-Hodgkin's lymphomas (0.37-0.63), Hodgkin's disease (0.61-0.81), and leukaemias (0.27-0.39). Survival for all cancers and both sexes combined, rose from 0.51 0.64 (0.57 for males, 0.71- for females). No appreciable change in survival was observed for cancers of oesophagus, liver, gallbladder, pancreas, larynx, cervix uteri, brain, multiple myeloma, as well as unidentified or unknown origin neoplasms.

CONCLUSIONS

Survival estimates for most cancer sites are comparable to the US SEER dataset, and their pattern of trends are discussed in terms of improved diagnosis and treatment for various neoplasms.

Detection of minimal residual disease in acute leukemia by flow cytometry

Patients with acute leukemia in clinical remission may still have up to 10(10) residual malignant cells (the upper limit of detection by standard morphologic techniques). Sensitive techniques to detect minimal residual disease (MRD) may allow better estimates of the leukemia burden and help the selection of appropriate therapeutic strategies. Flow cytometry and polymerase chain reaction have emerged as the most promising methods for detecting submicrospopic levels of leukemia. Flowcytometric detection of MRD is based on the identification of immunophenotypic combinations expressed on leukemic cells but not on normal hematopoietic cells. It affords the detection of one leukemic cell among 10,000 normal bone marrow cells, and can be currently applied to at least two thirds of all patients with acute leukemia. Prospective studies in large series of patients have demonstrated a strong correlation between MRD levels during clinical remission and treatment outcome. Therefore, MRD assays can be reliably used to assess early response to treatment and predict relapse. In this review, we discuss methodologic aspects and clinical results of flowcytometric detection of MRD in patients with acute leukemia.