Validation of Western common recurrent chromosomal aberrations in Korean chronic lymphocytic leukaemia patients with very low incidence

Characteristics of chronic lymphocytic leukemia in Japan: Comprehensive analysis of the CLLRSG-01 study

Chronic lymphocytic leukemia (CLL) is rare in Japan. We conducted the nationwide, prospective observational study CLLRSG-01 to clarify the current state of CLL in Japan and to make accurate international comparisons by preparing naturally air-dried smears like those used in other countries. Of the 201 untreated patients enrolled and evaluated, 119 were diagnosed with CLL and 82 with non-CLL mature B-cell neoplasms, based on the WHO classification. Of the 119 CLL patients, 90 were classified as typical and 29 as atypical according to FAB classification morphology, with the proportion of atypical CLL consistent with reports from other countries. Immunophenotypic analyses by flow cytometry showed that 55% of Japanese CLL patients had a Matutes score of 4 or higher, which is lower than the rate of about 90% in Europeans. Mutated IGHV was identified in 80% of Japanese CLL patients, which is a higher rate than in Western patients. The most frequent IGHV gene was VH3-30 (15%), followed by VH3-23 (12%) and VH4-34 (10%). VH1-69, the most common gene in Western countries, was identified in only one patient. These results indicate that the pattern of immunophenotypes and IGHV gene usage in Japanese CLL patients differs from that in Western patients.

Genetic and Clinical Characteristics of Korean Chronic Lymphocytic Leukemia Patients with High Frequencies of MYD88 Mutations

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries. However, CLL is relatively rare in Asia; its genetic features are rarely studied. Here, we aimed to genetically characterize Korean CLL patients and to elucidate the genetic and clinical associations based on data obtained from 113 patients at a single Korean institute. We used next-generation sequencing to explore the multi-gene mutational data and immunoglobulin heavy chain variable gene clonality with somatic hypermutation (SHM). MYD88 (28.3%), including L265P (11.5%) and V217F (13.3%), was the most frequently mutated gene, followed by KMT2D (6.2%), NOTCH1 (5.3%), SF3B1 (5.3%), and TP53 (4.4%). MYD88-mutated CLL was characterized by SHM and atypical immunophenotype with fewer cytogenetic abnormalities. The 5-year time to treatment (TTT) of the overall cohort was 49.8% ± 8.2% (mean ± standard deviation) and the 5-year overall survival was 86.2% ± 5.8%. Patients with SHM, isolated del(13q), TP53-wild type, and NOTCH1-wild type showed better results than those without these conditions. In the subgroup analyses, patients with SHM and L265P presented shorter TTT than patients with SHM but not L265P. In contrast, V217F was associated with a higher SHM percentage and showed a favorable prognosis. Our study revealed the distinct characteristics of Korean CLL patients with high frequencies of MYD88 mutations and their clinical relevance.

Low prevalence and independent prognostic role of del(11q) in Chinese patients with chronic lymphocytic leukemia

The 11q deletion (del(11q)) is a conventional cytogenetic aberration observed in chronic lymphocytic leukemia (CLL) patients. However, the prevalence and the prognostic value of del(11q) are still controversial. In this research, we retrospectively explored the prevalence, association, and prognostic significance of del(11q) in 352 untreated and 99 relapsed/refractory Chinese CLL patients. Totally 11.4% of untreated and 19.2% of relapsed/refractory patients harbored del(11q). Del(11q) was more common in patients with β2-microglobulin > 3.5 mg/L, positive CD38, positive zeta-chain associated protein kinase 70, unmutated immunoglobulin heavy variable-region gene and ataxia telangiectasia mutated mutation. Kaplan-Meier method and univariate Cox regression indicated that del(11q) was an independent prognostic factor for overall survival (OS). Based on the results of univariate Cox regression analysis, two nomograms that included del(11q) were established to predict survival. Desirable area under curve of receiver operating characteristic curves was obtained in the training and validation cohorts. In addition, the calibration curves for the probability of survival showed good agreement between the prediction by nomogram and actual observation. In summary, the prevalence of del(11q) is relatively low in our cohort and del(11q) is an unfavorable prognostic factor for untreated CLL patients. Besides, these two nomograms could be used to accurately predict the prognosis of untreated CLL patients.

Distinct immunoglobulin heavy chain variable region gene repertoire and lower frequency of del(11q) in Taiwanese patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in Western countries but very rare in Asia. Peripheral blood or bone marrow mononuclear cells obtained at initial diagnosis from 194 patients with CLL were analysed to determine the ethnic difference in genetic abnormalities. Mutated IGHV was detected in 71·2% of Taiwanese CLL and IGHV3‐23 was the most frequently used gene. Stereotyped BCR was present in 18·3% with subset 8 being the most frequent. All cases with subset 8 belonged to IGHV 4‐39 and were exclusively associated with un‐mutated IGHV and poor outcome. Mutation frequencies of SF3B1 (9·7%), NOTCH1 (8·6%), BIRC3 (1·1%), ATM (16·9%) or TP53 (8·1%), and frequencies of cytogenetic abnormalities including trisomy 12 (18·6%), del(17p) (10·4%), del(13q) (43·7%) and IGH translocation (10·1%) were comparable to those reported from Western countries, except del(11q) (6·9%) which was lower in our patients. Patients with un‐mutated IGHV, subset 8, disrupted TP53, trisomy 12, and SF3B1 mutations had a worse outcome compared to patients without these mutations. In conclusion, IGHV3‐23 usage, stereotyped subset 8 and lower frequency of del(11q) show an ethnicity‐dependent association in Taiwanese CLL patients.

Altered expression of MALAT1 lncRNA in chronic lymphocytic leukemia patients, correlation with cytogenetic findings

Background

Recent studies have devoted much attention to non-protein-coding transcripts in relation to a wide range of malignancies. MALAT1, a long non-coding RNA, has been reported to be associated with cancer progression and prognosis. Thus, we here determined MALAT1 gene expression in chronic lymphocytic leukemia (CLL), a genetically heterogeneous disease, and explored its possible relationships with cytogenetic abnormalities.

Methods

MALAT1 expression level was evaluated using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) on blood mononuclear cells from 30 non-treated CLL patients and 30 matched healthy controls. Cytogenetic abnormalities were determined in patients by fluorescence in situ hybridization (FISH).

Results

MALAT1 expression level was up-regulated in the CLL group compared to healthy controls (P=0.008). Del13q14, followed by Del11q22, were the most prevalent cytogenetic abnormalities. We found no association between the FISH results and MALAT1 expression in patients.

Conclusion

Altered expression of MALAT1 is associated with CLL development. Further investigations are required to assess the relationship between this long non-coding RNA and CLL patient survival and prognosis.

Pharmacokinetics of the BCL-2 Inhibitor Venetoclax in Healthy Chinese Subjects

Venetoclax has been approved in the United States, Europe, Canada, and Australia for appropriate patients with difficult-to-treat chronic lymphocytic leukemia (CLL). The objective of this phase 1 study was to evaluate the pharmacokinetics of venetoclax in Chinese subjects to inform the dose selection of venetoclax in a phase 2 study of patients with relapsed/refractory (R/R) CLL in China. Twelve healthy first-generation Han Chinese subjects received a single 100-mg dose of venetoclax following a low-fat breakfast. Pharmacokinetic parameters were estimated using noncompartmental methods. After a single dose of venetoclax in healthy Chinese subjects, the median time to peak concentration was 6 hours (range, 4 to 6 hours), and the mean ± SD C_max , AUC_inf , and terminal half-life were 1.0 ± 0.32 μg/mL, 12.6 ± 5.4 μg·h/mL, and 18.4 ± 2.97 hours, respectively. On average, venetoclax C_max and AUC_inf values were 94% and 66% higher, respectively, in Chinese subjects compared with those observed historically for non-Asian subjects receiving the same dose. Based on these pharmacokinetic results and the established exposure-response relationship of venetoclax in non-Asian CLL subjects, a 400-mg once-daily dosage regimen was selected for evaluating the venetoclax pharmacokinetics, efficacy, and safety in the venetoclax phase 2 open-label study in Chinese subjects with R/R CLL.

Genomic Profile of Chronic Lymphocytic Leukemia in Korea Identified by Targeted Sequencing

Chronic lymphocytic leukemia (CLL) is extremely rare in Asian countries and there has been one report on genetic changes for 5 genes (TP53, SF3B1, NOTCH1, MYD88, and BIRC3) by Sanger sequencing in Chinese CLL. Yet studies of CLL in Asian countries using Next generation sequencing have not been reported. We aimed to characterize the genomic profiles of Korean CLL and to find out ethnic differences in somatic mutations with prognostic implications. We performed targeted sequencing for 87 gene panel using next-generation sequencing along with G-banding and fluorescent in situ hybridization (FISH) for chromosome 12, 13q14.3 deletion, 17p13 deletion, and 11q22 deletion. Overall, 36 out of 48 patients (75%) harbored at least one mutation and mean number of mutation per patient was 1.6 (range 0-6). Aberrant karyotypes were observed in 30.4% by G-banding and 66.7% by FISH. Most recurrent mutation (>10% frequency) was ATM (20.8%) followed by TP53 (14.6%), SF3B1 (10.4%), KLHL6 (8.3%), and BCOR (6.25%). Mutations of MYD88 was associated with moderate adverse prognosis by multiple comparisons (P = 0.055). Mutation frequencies of MYD88, SAMHD1, EGR2, DDX3X, ZMYM3, and MED12 showed similar incidence with Caucasians, while mutation frequencies of ATM, TP53, KLHL6, BCOR and CDKN2A tend to be higher in Koreans than in Caucasians. Especially, ATM mutation showed 1.5 fold higher incidence than Caucasians, while mutation frequencies of SF3B1, NOTCH1, CHD2 and POT1 tend to be lower in Koreans than in Caucasians. However, mutation frequencies between Caucasians and Koreans were not significantly different statistically, probably due to low number of patients. Collectively, mutational profile and adverse prognostic genes in Korean CLL were different from those of Caucasians, suggesting an ethnic difference, while profile of cytogenetic aberrations was similar to those of Caucasians.

Immunoglobulin gene translocations in chronic lymphocytic leukemia: A report of 35 patients and review of the literature

Chronic lymphocytic leukemia (CLL) represents the most common hematological malignancy in Western countries, with a highly heterogeneous clinical course and prognosis. Translocations involving the immunoglobulin (IG) genes are regularly identified. From 2000 to 2014, we identified an IG gene translocation in 18 of the 396 patients investigated at diagnosis (4.6%) and in 17 of the 275 analyzed during follow-up (6.2%). A total of 4 patients in whom the IG translocation was identified at follow-up did not carry the translocation at diagnosis. The IG heavy locus (IGH) was involved in 27 translocations (77.1%), the IG κ locus (IGK) in 1 (2.9%) and the IG λ locus (IGL) in 7 (20.0%). The chromosome band partners of the IG translocations were 18q21 in 16 cases (45.7%), 11q13 and 19q13 in 4 cases each (11.4% each), 8q24 in 3 cases (8.6%), 7q21 in 2 cases (5.7%), whereas 6 other bands were involved once (2.9% each). At present, 35 partner chromosomal bands have been described, but the partner gene has solely been identified in 10 translocations. CLL associated with IG gene translocations is characterized by atypical cell morphology, including plasmacytoid characteristics, and the propensity of being enriched in prolymphocytes. The IG heavy chain variable region (IGHV) mutational status varies between translocations, those with unmutated IGHV presumably involving cells at an earlier stage of B-cell lineage. All the partner genes thus far identified are involved in the control of cell proliferation and/or apoptosis. The translocated partner gene becomes transcriptionally deregulated as a consequence of its transposition into the IG locus. With the exception of t(14;18)(q32;q21) and its variants, prognosis appears to be poor for the other translocations. Therefore, searching for translocations involving not only IGH, but also IGL and IGK, by banding and molecular cytogenetics is required. Furthermore, it is important to identify the partner gene to ensure the patients receive the optimal treatment.

Chronic lymphocytic leukemia: a clinical review including Korean cohorts

Only 5th decade ago, chronic lymphocytic leukemia (CLL) was only recognized as disease group of presenting features like peripheral lymphocytosis, organomegaly including of splenomegaly. As understanding of disease biology and molecular diagnostic tools are getting improved gradually, characterization of variation in CLL's clinical courses was facilitated, resulting in better risk stratification and targeted treatments. Consequently multiple new targeted agents have been used in treatment of CLL, it makes improved clinical outcome. Rituximab containing chemoimmunotherapy (combination of rituximab, fludarabine, and cyclophosphamide) have shown better overall response rate and progression-free survival on fit patients' group in front-line setting, result in standard first-line therapeutic option for CLL. Furthermore, after introducing that the B-cell receptor is crucial for the evolution and progression of CLL, emerging treatments targeting highly activated surface antigens and oncogenic signaling pathways have been associated with several successes in recent decades. These include new anti-CD 20 monoclonal antibody (obinutuzumab), the bruton tyrosine kinase inhibitor (ibrutinib), the phosphatidylinositol 3-kinase inhibitor (idelalisib), and B-cell CLL/lymphoma 2 inhibitor (ABT-199 and ABT-263). So, we discuss not only general pathophysiology of CLL, but also rapidly advancing treatment strategies that are being studied or approved for treatment of CLL.

Incidence of chromosomal anomalies detected by interphase FISH in chronic lymphoid leukemia

Aims & methods: We used interphase FISH to determine the incidence of chromosomal changes in 638 B-cell chronic lymphocytic leukemia patients. Results: Chromosomal abnormalities were found in some 75% of the patients. Del(13)(q14) was present in 57.3 and 57% of patients at diagnosis and during follow-up, respectively. It was followed by trisomy 12 (19 and 19.8% at diagnosis and during follow-up, respectively), del(11)(q22) (9.1 and 14.3% at diagnosis and during follow-up, respectively) and del(17)(p13) (2.8 and 12.4% at diagnosis and during follow-up, respectively). Discussion & conclusion: Our results correlate with those obtained in 55 studies reported in the literature. Trisomy 12 and del(13)(q14) are present in high proportions at diagnosis and are not enriched during progression, to the contrary of del(11)(q22) and del(17)(p13) that are markers of evolution.

The mystery of chronic lymphocytic leukemia (CLL): Why is it absent in Asians and what does this tell us about etiology, pathogenesis and biology?

Chronic lymphocytic leukemia/small lymphocytic lymphoma is common in persons of predominately European descent but rare in Asians. Why is unknown but is likely genetically-determined. Environmental factors may also operate but are likely to be less important. When CLL occurs in Asians it has different features than CLL in persons of predominately European descent. The reason(s) for this is also not understood. We reviewed data on CLL in Asians (mostly Han Chinese but also other ethnic groups) and compared these data with those from persons of predominately European descent with CLL. CLL incidence was about 5-10-fold less in Asians. Asians with CLL are younger, have atypical morphologic and immunologic features, an increased proportion of IGHV mutations and rearrangements and briefer freedom-from-progression than persons of predominately European descent with CLL. These observations provide clues to the etiology and biology of CLL. But the mystery continues; more research is needed.

Comprehensive chronic lymphocytic leukemia diagnostics by combined multiplex ligation dependent probe amplification (MLPA) and interphase fluorescence in situ hybridization (iFISH)

Background

Banding-karyotyping and metaphase-directed-fluorescence-in-situhybridization (FISH) may be hampered by low mitotic index in leukemia. Interphase FISH (iFISH) is a way out here, however, testing many probes at the same time is protracted and expensive. Here multiplex-ligation-dependent-probe-amplification (MLPA) was used retrospectively in chronic lymphocytic leukemia (CLL) samples initially studied by banding cytogenetics and iFISH. Detection rates of iFISH and MLPA were compared and thus a cost-efficient scheme for routine diagnostics is proposed.

Results

Banding cytogenetics was done successfully in 67/85 samples. DNA was extracted from all 85 CLL samples. A commercially available MLPA probe set directed against 37 loci prone to be affected in hematological malignancies was applied. Besides, routine iFISH was done by commercially available probes for following regions: 11q22.3, 12p11.2-q11.1, 13q14.3, 13q34, 14q32.33 and 17p13.1. MLPA results were substantiated by iFISH using corresponding locus-specific probes.

Aberrations were detected in 67 of 85 samples (~79%) applying banding cytogenetics, iFISH and MLPA. A maximum of 8 aberrations was detected per sample; however, one aberration per sample was found most frequently. Overall 163 aberrations were identified. 15 of those (~9%) were exclusively detected by banding cytogenetics, 95 were found by MLPA (~58%) and 100 (~61%) by routine iFISH. MLPA was not able to distinguish reliably between mono- and biallelic del(13)(q14.3q14.3), which could be easily identified as well as quantified by routine iFISH. Also iFISH was superior to MLPA in samples with low tumor cell load. On the other hand MLPA detected additional aberrations in 22 samples, two of them being without any findings after routine iFISH.

Conclusions

Both MLPA and routine iFISH have comparable detection rates for aberrations being typically present in CLL. As MLPA can detect also rare chromosomal aberrations it should be used as an initial test if routine cytogenetics is not possible or non-informative. Still iFISH should be used additionally to distinguish mono- from biallelic deletions and also to determine rate of mosaicism for 13q14.2 to 13q14.3. In case MLPA is negative the corresponding CLL samples should be tested at least by iFISH using the standard probe set to.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-014-0079-2) contains supplementary material, which is available to authorized users.

CpG Oligonucleotide and Interleukin 2 stimulation enables higher cytogenetic abnormality detection rates than 12-o-tetradecanolyphorbol-13-acetate in Asian patients with B-cell chronic lymphocytic leukemia (B-CLL)

The present study was designed to compare abnormality detection rates using DSP30 + IL2 and 12-O-Tetradecanoylphorbol-13-acetate (TPA) in Asian patients with B-CLL. Hematological specimens from 47 patients (29 newly diagnosed, 18 relapsed) were established as 72 h-DSP30 + IL2 and TPA cultures. Standard methods were employed to identify clonal aberrations by conventional cytogenetics (CC). The B-CLL fluorescence in situ hybridization (FISH) panel comprised ATM, CEP12, D13S25, and TP53 probes. DSP30 + IL2 cultures had a higher chromosomal abnormality detection rate (67 %) compared to TPA (44 %, p < 0.001). The mean number of analyzable metaphases and abnormal metaphases per slide was also higher (p < 0.005, p < 0.001, respectively). Culture success rate, percentage of complex karyotype, and percentage of non-clonal abnormal cell were not significantly different (p > 0.05). Thirteen cases with abnormalities were found exclusively in DSP30 + IL2 cultures compared to one found solely in TPA cultures. DSP30 + IL2 cultures were comparable to the FISH panel in detecting 11q-, +12 and 17p- but not 13q-. It also has a predilection for 11q- bearing leukemic cells compared to TPA. FISH had a higher abnormality detection rate (84.1 %) compared to CC (66.0 %) with borderline significance (p = 0.051), albeit limited by its coverage. In conclusion, DSP30 + IL2 showed a higher abnormality detection rate. However, FISH is indispensable to circumvent low mitotic indices and detect subtle abnormalities.