Cytogenetics in acute myeloid leukaemia

Efficacy and safety of different doses of cytarabine in consolidation therapy for adult acute myeloid leukemia patients: a network meta-analysis

Cytarabine (Ara-C) in consolidation therapy played important role in preventing relapses for AML patients achieved complete remission, but the optimum dose remains elusive. In this network meta-analysis, we compared benefit and safety of high-, intermediate- and low-dose Ara-C [HDAraC (>2 g/m², ≤3 g/m² twice daily), IDAraC (≥1 g/m², ≤2 g/m² twice daily) and LDAraC (<1 g/m² twice day)] in consolidation, based on ten randomized phase III/IV trials from 1994 to 2016, which included 4008 adult AML patients. According to the results, HDAraC in a dosage of 3 g/m² twice daily significantly improved disease-free survival (DFS) compared with IDAraC [hazard rate (HR) 0.87, 95% CrI 0.79–0.97) and LDAraC (HR 0.86, 95% CrI 0.78–0.95). Subgroup analysis further showed that the DFS advantage of HDAraC is focused on the patients with favorable cytogenetics, but not the other cytogenetics. Compared with LDAraC, HDAraC (HR 6.04, 95% CrI 1.67–21.49) and IDAraC (HR 3.80, 95% CrI 1.05–12.85) were associated with higher risk of grade 3–4 non-haematological toxicity. However, no significant difference between HDAraC and IDAraC was found. These findings suggest that Ara-C in a dosage of 3 g/m² twice daily provides maximal anti-relapse effect.

Promoter DNA methylation and expression levels of HOXA4, HOXA5 and MEIS1 in acute myeloid leukemia

HOXA genes encode transcription factors, which are crucial for embryogenesis and tissue differentiation and are involved in the early stages of hematopoiesis. Aberrations in HOXA genes and their cofactor MEIS1 are found in human neoplasms, including acute myeloid leukemia (AML). The present study investigated the role of HOXA4, HOXA5 and MEIS1 promoter DNA methylation and mRNA expression in AML. Samples from 78 AML patients and 12 normal bone marrow (BM) samples were included. The levels of promoter DNA methylation were determined using quantitative methylation‑specific polymerase chain reaction (PCR; qMSP) and the relative expression levels were measured using reverse transcription quantitative PCR in Ficoll‑separated BM mononuclear cells and in fluorescent activated cell sorting‑sorted populations of normal hematopoietic progenitors. In total, 38.1 and 28.9% of the patients exhibited high methylation levels of HOXA4 and HOXA5, respectively, compared with the control samples, and MEIS1 methylation was almost absent. An inverse correlation between HOXA4 methylation and expression was identified in a group of patients with a normal karyotype (NK AML). An association between the genes was observed and correlation between the DNA methylation and expression levels of the HOXA gene promoter with the expression of MEIS1 was observed. Patients with favorable chromosomal aberrations revealed a low level of HOXA4 methylation and decreased expression levels of HOXA5 and MEIS1 compared with the NK AML and the adverse cytogenetic risk patients. The NK AML patients with NPM1 mutations exhibited elevated HOXA4 methylation and expression levels of HOXA5 and MEIS1 compared with the NPM1 wild‑type patients. Comparison of the undifferentiated BM‑derived hematopoietic CD34+CD38low, CD34+CD38+ and CD15+ cells revealed a gradual decrease in the expression levels of these three genes and an increase in HOXA4 promoter methylation. This differentiation‑associated variability was not observed in AML, which was classified according to the French‑American‑British system.

Epigenetics in myeloid malignancies

Myeloid hematological malignancies are among the epigenetically best characterized neoplasms. The comparatively low number of recurring balanced and unbalanced chromosomal abnormalities as well as common genetic mutations has enabled scientists to relate epigenetic states to these. The ease of accessing malignant cells through bone marrow aspiration has certainly contributed to the fast expansion of knowledge. Even so, the clinical and pathogenetic relevance of epigenetic changes is still not known, and the field will certainly evolve very fast with the development of new analytic techniques. The first example of successful epigenetic therapy is seen in myeloid malignancies, in the high-risk myelodysplastic syndromes (MDS) which are routinely treated with the demethylating agent azacytidine.This chapter will concentrate on describing the epigenetic changes in acute myeloid leukemia (AML), chronic myeloid leukemia (CML) and MDS. An overview of clinical relevance and epigenetic therapeutic approaches is also made.

Prediction of post-remission survival in acute myeloid leukaemia: a post-hoc analysis of the AML96 trial

BACKGROUND

The optimum post-remission treatment (PRT) in acute myeloid leukaemia (AML) is still a matter of debate. Consolidation treatments include chemotherapy with high-dose cytarabine, or allogeneic or autologous haemopoietic stem cell transplantation (HSCT). In a post-hoc analysis of the AML96 trial (NCT00180115), our aim was to differentiate groups of patients according to the treatments that would provide them optimum benefit.

METHODS

In the multicentre AML96 trial, 586 patients (aged 15-60 years) with AML--excluding those with t(8;21)--who were in complete remission after double induction treatment were consolidated with allogeneic HSCT, autologous HSCT, or chemotherapy containing high-dose cytarabine in a priority-based and risk-adapted manner. We assessed the association between potentially prognostic variables and overall survival after complete remission by use of a stratified Cox regression analysis. With the significant variables of the resulting model, we developed a PRT score in 452 patients with a complete dataset. This score was then validated by use of data from 407 patients from the AML2003 trial (NCT00180102).

FINDINGS

Age, percentage of CD34-positive blasts, FLT3-ITD mutant-to-wild-type ratio, cytogenetic risk, and de-novo or secondary AML were identified as independent prognostic factors, and included in the PRT score. The PRT score separated patients in AML96 into three groups: favourable (n=190; 3-year survival 68%, 95% CI 60-74), intermediate (n=198; 49%, 42-56), and unfavourable (n=64; 20%, 12-31). All pair-wise comparisons of two of three PRT score groups were significant in the log-rank test (p<0·0001). Similar results were noted when data from AML2003 were used: 3-year survival for the favourable group (n=265) was 69% (62-76), for the intermediate group (n=114) it was 61% (50-71), and for the unfavourable group (n=28) it was 46% (24-65). The overall comparison between the three risk groups resulted in significantly different survival probabilities (p=0·015). We also analysed response to treatment in AML96 in each of the PRT score groups. In the favourable group, patients given allogeneic HSCT (n=60) had higher survival probabilities (82%, 69-89) than did those given chemotherapy (n=56, 55%, 41-67; p=0·0012) or autologous HSCT (n=74, 66%, 54-76; p=0·044). In the intermediate PRT score group, patients given autologous HSCT (n=69) had the best survival probabilities (62%, 50-72) compared with those given chemotherapy (n=72, 41%, 30-52; p=0·0006) or allogeneic HSCT (n=57, 44%, 31-56; p=0·0045).

INTERPRETATION

The PRT score groups could help physicians to tailor treatment for patients with AML and our results lend support to the use of autologous HSCT in patients aged 60 years or younger with an intermediate PRT score.

FUNDING

Deutsche Krebshilfe.

Cytarabine Dose of 36 g/m2 Compared With 12 g/m2 Within First Consolidation in Acute Myeloid Leukemia: Results of Patients Enrolled Onto the Prospective Randomized AML96 Study

Purpose

To assess the optimal cumulative dose of cytarabine for treatment of young adults with acute myeloid leukemia (AML) within a prospective multicenter treatment trial.

Patients and Methods

Between 1996 and 2003, 933 patients (median age, 47 years; range 15 to 60 years) with untreated AML were randomly assigned at diagnosis to receive cytarabine within the first consolidation therapy at either a intermediate-dose of 12 g/m2 (I-MAC) or a high-dose of 36 g/m2 (H-MAC) combined with mitoxantrone. Autologous hematopoietic stem-cell transplantation or intermediate-dose cytarabine (10 g/m2) were offered as second consolidation. Patients with a matched donor could receive an allogeneic transplantation in a risk-adapted manner.

Results

After double induction therapy including intermediate-dose cytarabine (10 g/m2), mitoxantrone, etoposide, and amsacrine, complete remission was achieved in 66% of patients. In the primary efficacy analysis population, a consolidation with either I-MAC or H-MAC did not result in significant differences in the 5-year overall (30% v 33%; P = .77) or disease-free survival (37% v 38%; P = .86) according to the intention-to-treat analysis. Besides a prolongation of neutropenia and higher transfusion demands in the H-MAC arm, rates of serious adverse events were comparable in the two groups.

Conclusion

In young adults with AML receiving intermediate-dose cytarabine induction, intensification of the cytarabine dose beyond 12 g/m2 within first consolidation did not improve treatment outcome.

Prognostic Impact of Specific Chromosomal Aberrations in a Large Group of Pediatric Patients With Acute Myeloid Leukemia Treated Uniformly According to Trial AML-BFM 98

Purpose

Because cytogenetic data are essential for risk stratification of childhood acute myeloid leukemia (AML), the impact of chromosomal aberrations is crucial.

Patients and Methods

Data of a large group of patients younger than 18 years treated according to study AML–Berlin-Frankfurt-Münster (BFM) 98 (n = 454), including their cytogenetics, were analyzed.

Results

The favorable outcome in the subgroups of patients with t(8;21), inv(16), and t(15;17), with an overall survival of 91% (SE, 4%), 92% (SE, 6%), and 87% (SE, 5%), respectively, was confirmed. Within this group, the 5-year probability of event-free survival (pEFS) of all 17 children with t(8;21) and additional aberrations apart from del(9q) or −X/−Y was 100%. As expected, the cytogenetic finding of a complex karyotype (n = 35; pEFS, 33%; SE, 8%) or a monosomy 7 (n = 12; pEFS, 17%; SE, 11%) was associated with a poor outcome. Compared with remaining patients with cytogenetic data (pEFS, 48%; SE, 2%), prognosis in patients with an MLL rearrangement (n = 91) was inferior (pEFS, 34%; SE, 5%; P = .0005). Particularly, children with t(9;11) and additional aberrations (n = 13; pEFS, 31%; SE, 14%) and MLL rearrangements other than t(9;11) and t(11;19) (n = 41; pEFS, 24%; SE, 7%) had an unfavorable outcome. Nine patients with aberrations in 12p showed an adverse prognosis (pEFS, 11%; SE, 10%). The outcome of patients with aberrations of chromosome 5 (n = 13) was better than expected (pEFS, 50%; SE, 13%).

Conclusion

Because the prognostic value of rare recurrent chromosomal aberrations still has to be elucidated, these data will contribute to future risk stratification for the treatment of pediatric AML.

Impact of cytogenetics on outcome of de novo and therapy-related AML and MDS after allogeneic transplantation

Cytogenetics has an important impact on the prognosis of patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) for acute myelogenous leukemia (AML) or myelodysplastic syndromes (MDS). However, it is unclear whether currently accepted cytogenetic risk groups, which were established for patients treated mostly with standard therapy, are optimally discriminating for patients undergoing HSCT. Also, the impact of cytogenetics in the growing population of patients with therapy-related disease has not been completely elucidated. In this study, we retrospectively analyzed data on 556 patients with AML or MDS transplanted at our institution. We examined, in multivariate analyses, the contribution of cytogenetics to survival, relapse, and nonrelapse mortality for the 476 patients with de novo disease. We used these results to establish an optimal cytogenetic grouping scheme. We then applied this grouping scheme to the 80 patients with therapy-related disease. Our proposed 3-group cytogenetic classification outperformed the established grouping schemes for both de novo and therapy-related disease. When classified by this new scheme, cytogenetics was the strongest prognostic factor for overall survival in our cohort, through its impact on the risk of relapse (and not on nonrelapse mortality). After accounting for cytogenetics, patients with therapy-related AML or MDS had an equivalent outcome to those with de novo disease. This study demonstrates the impact of cytogenetics on the risk of relapse and death for patients with both de novo and therapy-related disease undergoing transplantation; it also emphasizes the necessity of using cytogenetics to stratify patients entering clinical trials, and provides a system for doing so, which can be validated in a multi-institutional database.

Genetic polymorphisms in microsomal epoxide hydrolase and susceptibility to adult acute myeloid leukaemia with defined cytogenetic abnormalities

Acute myeloid leukaemia (AML) cases with different chromosomal abnormalities may reflect different aetiologies. Benzene exposure, from a number of sources including smoking, is one risk factor for AML. Individual susceptibility to benzene may depend on differences in expression of metabolizing enzymes. We tested the hypothesis that smoking as well as genetic polymorphisms in the microsomal epoxide hydrolase gene (HYL1), an enzyme involved in benzene metabolism, could be risk factors for AML with defined chromosomal abnormalities. Twenty-six AML cases with -7/del(7q) and 24 cases with t(8;21), as well as 43 cases with normal karyotype and 155 age-, sex- and residence-matched controls, were drawn from a large case-control study on adult acute leukaemia. Current smoking was significantly associated with the cytogenetic abnormalities t(8;21) or -7/del(7q) (OR = 4.9; 95%CI = 2.1-11.5) but not with a normal karyotype, relative to individuals who were not current smokers. A putative high activity HYL1 phenotype [exon 3, residue 113 (Tyr/Tyr) and exon 4, residue 139 (His/Arg or Arg/Arg)] was associated with a significantly increased AML risk in men with -7/del(7q) or t(8;21) (OR = 4.4; 95%CI 1.1-17.0) but not with a normal karyotype. This suggests that AML cases with defined chromosomal abnormalities could be related to specific carcinogen exposures and, furthermore, suggests that smoking and genetic polymorphisms in HYL1 could be risk factors for AML with -7/del(7q) or t(8;21).

Minimal residual disease (MRD) in remission t(8;21) AML and in vivo differentiation detected by FISH and CD34+ cell sorting

Many patients with t(8;21) AML have residual positive cells during remission. We previously developed D-FISH probes that detect both derivative chromosomes and the normal alleles. In negative controls, only 2/44,000 (0.0045%) positive signals were observed. To investigate MRD, we examined specimens from 29 patients who had initially obtained CR. In remission patients, 61% had 1-4/2000 positive cells (0.05-0.19%). Higher frequencies were found in two patients in early relapse and in one patient in early remission. However, a negative test did not exclude relapse. Since false positives were negligible and because most t(8;21) AMLs express CD34, we asked whether cell sorting combined with FISH would increase the sensitivity. In one patient, we observed that 80% of CD34+ cells were t(8;21)+ at 2 months from initial clinical and cytogenetic remission. However, by 5 months the pre- and post-sorted populations contained 0.15% and 0.06% t(8;21) cells, respectively. Whereas essentially all t(8;21) cells in the initial specimen expressed CD34, only 0.6% were subsequently CD34+. These results are consistent with in vitro assays showing that residual t(8;21) cells undergo differentiation. Thus, FISH can identify MRD in a majority of t(8;21) patients and, combined with CD34+ selection, may provide an indirect assessment of the differentiation state of residual t(8;21) cells.

Trisomy 15 is frequently observed as a minor clone in patients with Anemia/MDS/NHL and as a major clone in patients with AML

Trisomy 15 as the sole karyotypic aberration is an uncommon clonal cytogenetic aberration in hematological malignancies, making its significance unclear. Previous studies have reported relations of trisomy 15 with low-grade myelodysplasia or a benign age-related phenomenon associated with loss of the Y chromosome. To define the significance of trisomy 15, we conducted a retrospective study of all examples of trisomy 15 accessed in our laboratories. Trisomy 15 was observed as a clonal abnormality (> or =2 cells) in 17 cases and nonclonal (single cell) in 9 cases. The majority of cases (14/17 clonal cases) had a minor clone (5-35% of metaphase cells) of trisomy 15. The minority of cases (3/17) had a major clone (80-95% of metaphase cells) of trisomy 15. Two of these 3 cases were diagnosed as having acute myelocytic leukemia. Fluorescence in-situ hybridization (FISH) with the use of a chromosome 15-specific alpha-satellite probe was performed on 3 of 17 clonal cases and on 3 of 9 nonclonal cases. FISH results revealed the presence of a minor clone (from 3 to 5 of 700 interphase cells) in 5 of them, 2 of which had trisomy 15 in 20% of metaphase cells. These results may indicate that the 20% of trisomy 15 are very likely an overrepresentation of a very minor clone that could be transitory. In summary, the analysis of our cytogenetic and FISH results revealed the presence of two types of trisomy 15 clones: a minor clone that could be transitory or indolent and a major clone that could be of a neoplastic nature.

Polysomy 13 with concomitant deletion of 13q13-14 involving the retinoblastoma gene and the D13S25 locus in a case of acute myeloid leukemia

We herein describe a case of acute myeloblastic leukemia (AML), FAB subtype M4, with an unfavorable clinical course and a complex karyotype, including 4-9 copies of chromosome 13. Polysomy 13 was a result of clonal evolution. Fluorescence in situ hybridization (FISH) revealed a cytogenetically unrecognizable deletion within 13q13-14 that included the retinoblastoma gene (RB) and the D13S25 locus in all but one copy of chromosome 13. The only chromosome 13 that did not show a deletion affecting the q13-14 region was translocated to chromosome 7, resulting in a dic(7;13)(q21;p11). In this case, the coexistence of polysomy and a partial deletion within the same chromosome point toward a possible formation of a fusion product with oncogenic potential and its consecutive amplification as a critical alteration in this case.

Child with mosaic variegated aneuploidy and embryonal rhabdomyosarcoma

We report on a 7-year-old boy with mosaic variegated aneuploidy (MVA) who developed embryonal rhabdomyosarcoma of the soft palate. This patient is the 11th case report of MVA and represents further documentation of the true existence of this rare mitotic mutant. Clinical findings share similarities to those previously described patients including microcephaly and growth retardation as the two most common abnormalities. Notably, mental retardation is not universally present. Results of serial cytogenetic analyses performed on somatic and neoplastic tissues are reviewed and compared with those of other previously reported patients. We postulate that mosaic variegated aneuploidy is causally related to the development of rhabdomyosarcoma in our patient. This is the first report of a patient with MVA who developed cancer and suggests that these patients may be at risk for malignancy and require long-term follow-up and cancer surveillance.

A further case of a t(11;20)(p15;q11.2) translocation in an acute myeloid leukemia (FAB M2)

PURPOSE

The clinical implications of many cytogenetic abnormalities in acute myeloid leukemia (AML) are now well established. However, questions about the significance of rarer abnormalities still exist, particularly in childhood disease.

PATIENTS AND METHODS

We report a case of a 9 1/2-year-old girl who had AML of the FAB M2 subtype. A diagnostic bone marrow aspirate and subsequent bone marrow aspirates were investigated using conventional cytogenetic methods.

RESULTS

Cytogenetic analysis of the diagnostic bone marrow aspirate showed a t(1;20)(p15;q11.2) translocation as the sole acquired abnormality. After one course of chemotherapy, the patient achieved hematopoietic and cytogenetic remission which has been sustained for 1 year after presentation.

CONCLUSION

This report demonstrates that rare non-random cytogenetic abnormalities are still to be described in AML, and that care should be taken when ascribing clinical significance to cytogenetic findings in childhood disease based on those of older patients.

Hematopoietic and lymphatic malignancies in vehicle mechanics

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

Fluorescent in situ hybridization (FISH) for the detection of trisomy 8 in acute myeloblastic leukemia

The karyotype of acute myeloid leukemia (AML) blasts has a major prognostic importance. However conventional cytogenetic studies of AML patients may fail to reveal chromosome abnormalities. Trisomy 8 is a common numerical abnormality in all AML subtypes. We evaluated the role of fluorescent in situ hybridization (FISH) in the detection of trisomy 8 in de-novo AML, and compared the results to chromosome analysis in some patients. Cytogenetic studies were performed in 9 of 12 patients. In three patients no metaphases were obtained. Of the remaining six, trisomy 8 was only detected in the metaphases of 1 patient. In contrast, 4 patients showed +8 with FISH and one had a borderline value. We conclude that FISH is a rapid and sensitive method to detect numerical aberrations in AML. In the future larger prospective studies should explore the biological and clinical application of the FISH method in different hematological malignancies.

Single-cell trisomy in hematologic malignancy. Random change or tip of the iceberg?

Finding a clone in the bone marrow of a patient with a hematologic disorder is important to confirm the neoplastic nature of the disease and may be indicative of prognosis. Since cytogenetic analysis detects only actively dividing clones, the presence of a single abnormal cell among 20 cells analyzed raises doubts about its clonal nature. Fluorescence in situ hybridization (FISH) enables rapid detection of certain chromosomal abnormalities in metaphase and interphase cells, thus enabling detection of minor or inactive clones. Seven patients with hematologic malignancy each having random cell(s) were investigated thus: at diagnosis, with MDS and a cell with +8 (two cases) or +9 (one case) and with AML and a cell with +4 (one case), +7 (one case), or two cells with +9, +22/ +10, +17, +17 (one case). One patient with ALL in remission had one cell with trisomy 4. One patient, a male aged 66 years with refractory anemia with ringed sideroblasts, was found to have a minor trisomy 8 clone in his diagnostic marrow. A follow-up marrow 42 months later showed no trisomy 8 cell among 62 metaphases analyzed, and the percentage of trisomic cells using FISH on interphase cells was within the control range. This patient has survived for more than 42 months requiring no treatment. Single-cell abnormalities in the other six cases proved to be random events. Thus it appears that single-cell abnormalities may not be clonal or at most indicate the presence of a minor clone well below the level of cytogenetic detection. The prognostic significance of such minor clones is at present unclear.

Detection of CBFB/MYH11 transcripts in patients with inversion and other abnormalities of chromosome 16 at presentation and remission

The pericentric inversion of chromosome 16 [inv(16)(p13q22)] and t(16;16)(p13;q22) are chromosomal rearrangements frequently associated with AML FAB type M4Eo resulting in the production of a fusion gene CBFB/MYH11. We studied 17 patients with a chromosome 16 abnormality (eight M4Eo, two M1, one M2, three M4 without abnormal eosinophils, three MDS) for the presence of CBFB/MYH11 transcripts using an RT-PCR technique. 10 AML patients with inv(16) tested RT-PCR positive (eight at presentation, one in remission, one in remission and relapse). Three of these patients were originally reported by cytogenetic analysis to have del(16q22) but the positive RT-PCR results prompted a cytogenetic re-examination, resulting in the correction of the reports to inv(16). We show that although inv(16) is closely associated with AML M4Eo, it can also be detected in cases of AML M4 without abnormal eosinophils. Three cases of MDS with inv(16) were also RT-PCR positive. Four patients with other chromosome 16 abnormalities were RT-PCR negative. Four AML patients with inv(16) were studied in remission. All were RT-PCR positive, including one patient in remission for 108 months and one 22 months post allogeneic bone marrow transplant. In the latter two remission patients, RT-PCR evaluation was positive in bone marrow (BM) but not in peripheral blood, suggesting that BM may be the more informative. We conclude that this technique is valuable in the accurate molecular classification of AML, particularly as treatment options may be influenced by such information. Though RT-PCR is highly sensitive in detecting CBFB/MYH11 fusion transcripts during remission, monitoring of minimal residual disease in patients with inv(16) remains to be established.