Karyotypic change between diagnosis and relapse as a predictor of salvage therapy outcome in AML patients

Prognostic significance of chromosomal abnormalities at relapse in children with relapsed acute myeloid leukemia: A retrospective cohort study of the Relapsed AML 2001/01 Study

BACKGROUND

In addition to treatment response, cytogenetic and molecular aberrations are the most important prognostic factors in children with de novo acute myeloid leukemia (AML). However, little is known about cytogenetics at the time of relapse.

METHODS

This international study analyzed the prognostic value of cytogenetic profiles and karyotypic changes in pediatric relapsed AML in relation to the probability of event-free (pEFS) and overall survival (pOS). For this purpose, cytogenetic reports from all patients registered on the Relapsed AML 2001/01 Study were reviewed and classified.

RESULTS

Cytogenetic information at relapse was available for 403 (71%) of 569 registered patients. Frequently detected aberrations at relapse were t(8;21)(q22;q22) (n = 60) and inv(16)(p13.1q22)/t(16;16)(p13.1;q22) (n = 24), both associated with relatively good outcome (4-year pOS 59% and 71%, respectively). Monosomy 7/7q-, t(9;11)(p22;q23), t(10;11)(p12;q23), and complex karyotypes were associated with poor outcomes (4-year pOS 17%, 19%, 22%, and 22%, respectively). Of 261 (65%) patients for whom cytogenetic data were reliable at both diagnosis and relapse, pEFS was inferior for patients with karyotypic instability (n = 128, 49%), but pOS was similar. Unstable karyotypes with both gain and loss of aberrations were associated with inferior outcome. Early treatment response, time to relapse, and cytogenetic profile at time of relapse were the most important prognostic factors, both outweighing karytoypic instability per se.

CONCLUSION

The cytogenetic subgroup at relapse is an independent risk factor for (event-free) survival. Cytogenetic assessment at the time of relapse is of high importance and may contribute to improved risk-adapted treatment for children with relapsed AML.

Prognostic Impact of Cytogenetic Evolution on the Outcome of Allogeneic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia in Nonremission: A Single-Institute Analysis of 212 Recipients

Recent progress in genetic analysis technology has helped researchers understand the pathogenesis of acute myeloid leukemia (AML). Considering this progress, AML karyotype is still one of the most significant prognostic factors that provides risk-adapted treatment approaches. Karyotype changes during treatment have been observed at times, but their prognostic impact is sparse, especially on allogeneic stem cell transplantation (allo-SCT). Here, we retrospectively investigated the effect of chromosomal changes between diagnosis and pretransplantation on the prognosis of allo-SCT by analyzing the outcomes of 212 consecutive patients who underwent allo-SCT for the first time at Toranomon Hospital, Tokyo, Japan, between 2008 and 2018. Cytogenetic abnormalities at diagnosis and pretransplantation were categorized based on the 2017 European Leukemia Net risk stratification. Genetic abnormalities such as FLT3-ITD and NPM1 were not considered in this study due to lack of genetic information in most patients. We defined cytogenetic evolution as chromosomal changes classified from lower category to higher category. Seventeen patients (8%) had cytogenetic evolution between diagnosis and pretransplantation, and they showed a significantly worse relapse rate than those who were categorized in the intermediate group based on the karyotype at diagnosis (3-year confidence interval [CI] of relapse, 57.4% versus 24.9%; P < .01). In multivariate analysis, cytogenetic evolution before allo-SCT had a significant impact on the CI of relapse (hazard ratio [HR], 3.89; CI, 1.75 to 8.67; P < .01), as well as the high score of the hematopoietic cell transplantation-specific comorbidity index (HR, 0.54; CI, 0.31 to 0.94; P = .03), but had no significant impact on overall survival or nonrelapse mortality. These results indicate that cytogenetic evolution has a significant impact after allo-SCT and should be considered during AML treatment.

Allogeneic hematopoietic stem cell transplantation can improve the prognosis of high-risk pediatric t(8;21) acute myeloid leukemia in first remission based on MRD-guided treatment

Background

Pediatric acute myeloid leukemia (AML) with t(8;21) (q22;q22) is classified as a low-risk group. However, relapse is still the main factor affecting survival. We aimed to investigate the effect of allogeneic hematopoietic stem cell transplantation (allo-HSCT) on reducing recurrence and improving the survival of high-risk pediatric t(8;21) AML based on minimal residual disease (MRD)-guided treatment, and to further explore the prognostic factors to guide risk stratification treatment and identify who will benefit from allo-HSCT.

Methods

Overall, 129 newly diagnosed pediatric t(8;21) AML patients were included in this study. Patients were divided into high-risk and low-risk group according to RUNX1-RUNX1T1 transcript levels after 2 cycles of consolidation chemotherapy. High-risk patients were divided into HSCT group and chemotherapy group according to their treatment choices. The characteristics and outcomes of 125 patients were analyzed.

Results

For high-risk patients, allo-HSCT could improve 5-year relapse-free survival (RFS) rate compared to chemotherapy (87.4% vs. 61.9%; P = 0.026). Five-year overall survival (OS) rate in high-risk HSCT group had a trend for better than that in high-risk chemotherapy group (82.8% vs. 71.4%; P = 0.260). The 5-year RFS rate of patients with a c-KIT mutation in high-risk HSCT group had a trend for better than that of patients with a c-KIT mutation in high-risk chemotherapy group (82.9% vs. 75%; P = 0.400). Extramedullary infiltration (EI) at diagnosis was associated with a high cumulative incidence of relapse for high-risk patients (50% vs. 18.4%; P = 0.004); allo-HSCT can improve the RFS (P = 0.009).

Conclusions

allo-HSCT can improve the prognosis of high-risk pediatric t(8;21) AML based on MRD-guided treatment. Patients with a c-KIT mutation may benefit from allo-HSCT. EI is an independent prognostic factor for high-risk patients and allo-HSCT can improve the prognosis.

Clonal evolution of acute myeloid leukemia from diagnosis to relapse

Based on the individual genetic profile, acute myeloid leukemia (AML) patients are classified into clinically meaningful molecular subtypes. However, the mutational profile within these groups is highly heterogeneous and multiple AML subclones may exist in a single patient in parallel. Distinct alterations of single cells may be key factors in providing the fitness to survive in this highly competitive environment. Although the majority of AML patients initially respond to induction chemotherapy and achieve a complete remission, most patients will eventually relapse. These points toward an evolutionary process transforming treatment-sensitive cells into treatment-resistant cells. As described by Charles Darwin, evolution by natural selection is the selection of individuals that are optimally adapted to their environment, based on the random acquisition of heritable changes. By changing their mutational profile, AML cell populations are able to adapt to the new environment defined by chemotherapy treatment, ultimately leading to cell survival and regrowth. In this review, we will summarize the current knowledge about clonal evolution in AML, describe different models of clonal evolution, and provide the methodological background that allows the detection of clonal evolution in individual AML patients. During the last years, numerous studies have focused on delineating the molecular patterns that are associated with AML relapse, each focusing on a particular genetic subgroup of AML. Finally, we will review the results of these studies in the light of Darwinian evolution and discuss open questions regarding the molecular background of relapse development.

Molecular and genetic alterations associated with therapy resistance and relapse of acute myeloid leukemia

Background

The majority of individuals with acute myeloid leukemia (AML) respond to initial chemotherapy and achieve a complete remission, yet only a minority experience long-term survival because a large proportion of patients eventually relapse with therapy-resistant disease. Relapse therefore represents a central problem in the treatment of AML. Despite this, and in contrast to the extensive knowledge about the molecular events underlying the process of leukemogenesis, information about the mechanisms leading to therapy resistance and relapse is still limited.

Purpose and content of review

Recently, a number of studies have aimed to fill this gap and provided valuable information about the clonal composition and evolution of leukemic cell populations during the course of disease, and about genetic, epigenetic, and gene expression changes associated with relapse. In this review, these studies are summarized and discussed, and the data reported in them are compiled in order to provide a resource for the identification of molecular aberrations recurrently acquired at, and thus potentially contributing to, disease recurrence and the associated therapy resistance. This survey indeed uncovered genetic aberrations with known associations with therapy resistance that were newly gained at relapse in a subset of patients. Furthermore, the expression of a number of protein coding and microRNA genes was reported to change between diagnosis and relapse in a statistically significant manner.

Conclusions

Together, these findings foster the expectation that future studies on larger and more homogeneous patient cohorts will uncover pathways that are robustly associated with relapse, thus representing potential targets for rationally designed therapies that may improve the treatment of patients with relapsed AML, or even facilitate the prevention of relapse in the first place.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0416-0) contains supplementary material, which is available to authorized users.

Evaluation of prognostic factors in patients with relapsed AML: Clonal evolution versus residual disease

Background

It is widely known that the prognosis of acute myeloid leukemia (AML) depends on chromosomal abnormalities. The majority of AML patients relapse and experience a dismal disease course despite initial remission.

Methods

We reviewed the medical records and laboratory findings of 55 AML patients who had relapsed between 2004 and 2013 and who had been treated at the Division of Hematology of the Pusan National University Hospital.

Results

The event-free survival (EFS) was related to prognostic karyotype classification at the time of diagnosis and relapse (unfavorable vs. favorable or intermediate karyotypes at diagnosis, 8.2 vs. 11.9 mo, P=0.003; unfavorable vs. favorable or intermediate karyotypes at relapse, 8.2 vs. 11.9 mo, P=0.009). The overall survival (OS) was significantly correlated with karyotype classification only at diagnosis (unfavorable vs. favorable or intermediate vs. karyotypes at diagnosis, 8.5 vs. 21.8 mo, P=0.001; unfavorable vs. favorable or intermediate karyotypes at relapse, 8.5 vs. 21.2 mo, P=0.136). A change in karyotype between diagnosis and relapse, which is regarded as a factor of resistance against treatment, was not a significant prognostic factor for OS, EFS, and post-relapse survival (PRS). A Cox proportional hazards model showed that the combined use of fludarabine, cytosine arabinoside, and granulocyte colony-stimulating factor (FLAG) as a salvage regimen, was a significant prognostic factor for OS (hazard ratio=0.399, P=0.010) and the PRS (hazard ratio=0.447, P=0.031).

Conclusion

The karyotype classification at diagnosis predicts survival including PRS in relapsed AML patients as well as in treatment-naïve patients. We suggest that presently, administration of salvage FLAG could be a better treatment option.

Considerations and challenges for patients with refractory and relapsed acute myeloid leukaemia

Despite advances in understanding the complexities of acute myeloid leukaemia (AML), the treatment of refractory or relapsed AML (rrAML) remains a daunting clinical challenge. Numerous clinical trials have failed to identify new treatments or combinations of existing therapies that substantially improve outcomes and survival. This may be due, at least in part, to heterogeneity among study patients with respect to multiple inter-related factors that have been shown to affect treatment outcomes for patients with rrAML; such factors include age, cytogenetics, immunophenotypic changes, and (in the case of relapsed AML) duration of first complete remission, or if the patient has had a previous blood and marrow transplant (BMT). A clear understanding of disease characteristics and patient-related factors that influence treatment response, as well as expected outcomes with existing and emerging therapies, can aid clinicians in helping their patients navigate through this complex disease state.

Detection of clonal evolution in hematopoietic malignancies by combining comparative genomic hybridization and single nucleotide polymorphism arrays

BACKGROUND

Array comparative genomic hybridization (aCGH) has become a powerful tool for analyzing hematopoietic neoplasms and identifying genome-wide copy number changes in a single assay. aCGH also has superior resolution compared with fluorescence in situ hybridization (FISH) or conventional cytogenetics. Integration of single nucleotide polymorphism (SNP) probes with microarray analysis allows additional identification of acquired uniparental disomy, a copy neutral aberration with known potential to contribute to tumor pathogenesis. However, a limitation of microarray analysis has been the inability to detect clonal heterogeneity in a sample.

METHODS

This study comprised 16 samples (acute myeloid leukemia, myelodysplastic syndrome, chronic lymphocytic leukemia, plasma cell neoplasm) with complex cytogenetic features and evidence of clonal evolution. We used an integrated manual peak reassignment approach combining analysis of aCGH and SNP microarray data for characterization of subclonal abnormalities. We compared array findings with results obtained from conventional cytogenetic and FISH studies.

RESULTS

Clonal heterogeneity was detected in 13 of 16 samples by microarray on the basis of log2 values. Use of the manual peak reassignment analysis approach improved resolution of the sample's clonal composition and genetic heterogeneity in 10 of 13 (77%) patients. Moreover, in 3 patients, clonal disease progression was revealed by array analysis that was not evident by cytogenetic or FISH studies.

CONCLUSIONS

Genetic abnormalities originating from separate clonal subpopulations can be identified and further characterized by combining aCGH and SNP hybridization results from 1 integrated microarray chip by use of the manual peak reassignment technique. Its clinical utility in comparison to conventional cytogenetic or FISH studies is demonstrated.