Multilineage involvement in KMT2A-rearranged B acute lymphoblastic leukaemia: cell-of-origin, biology, and clinical implications.

AIMS: B lymphoblastic leukaemia/lymphoma (B-ALL) is thought to originate from Pro/Pre-B cells and the genetic aberrations largely reside in lymphoid-committed cells. A recent study demonstrated that a proportion of paediatric B-ALL patients have BCR::ABL1 fusion in myeloid cells, suggesting a chronic myeloid leukaemia (CML)-like biology in this peculiar subset of B-ALL, although it is not entirely clear if the CD19-negative precursor compartment is a source of the myeloid cells. Moreover, the observation has not yet been extended to other fusion-driven B-ALLs. METHODS AND RESULTS: In this study we investigated a cohort of KMT2A-rearranged B-ALL patients with a comparison to BCR::ABL1-rearranged B-ALL by performing cell sorting via flow cytometry followed by FISH (fluorescence in situ hybridization) analysis on each of the sorted populations. In addition, RNA sequencing was performed on one of the sorted populations. These analyses showed that (1) multilineage involvement was present in 53% of BCR::ABL1 and 36% of KMT2A-rearranged B-ALL regardless of age, (2) multilineage involvement created pitfalls for residual disease monitoring, and (3) HSPC transcriptome signatures were upregulated in KMT2A-rearranged B-ALL with multilineage involvement. CONCLUSIONS: In summary, multilineage involvement is common in both BCR::ABL1-rearranged and KMT2A-rearranged B-ALL, which should be taken into consideration when interpreting the disease burden during the clinical course.

Immunochemotherapy plus lenalidomide for high-risk mantle cell lymphoma with measurable residual disease evaluation.

Chemoimmunotherapy followed by consolidative high-dose therapy with autologous stem cell rescue was a standard upfront treatment for fit patients with mantle cell lymphoma (MCL) in first remission; however, treatment paradigms are evolving in the era of novel therapies. Lenalidomide is an immunomodulatory agent with known efficacy in treating MCL. We conducted a single-center, investigator-initiated, phase II study of immunochemotherapy incorporating lenalidomide, without autologous stem cell transplant consolidation, enriching for patients with high-risk MCL (clinicaltrials gov. Identifier: NCT02633137). Patients received four cycles of lenalidomide-R-CHOP, two cycles of R-HiDAC, and six cycles of R-lenalidomide. The primary endpoint was rate of 3-year progression-free survival. We measured measurable residual disease (MRD) using a next-generation sequencing-based assay after each phase of treatment and at 6 months following end-oftreatment. We enrolled 49 patients of which 47 were response evaluable. By intent-to-treat, rates of overall and complete response were equivalent at 88% (43/49), one patient with stable disease, and two patients had disease progression during study; 3-year progression-free survival was 63% (primary endpoint not met) and differed by TP53 status (78% wild-type vs. 38% ALT; P=0.043). MRD status was prognostic and predicted long-term outcomes following R-HiDAC and at 6 months following end-of-treatment. In a high-dose therapy-sparing, intensive approach, we achieved favorable outcomes in TP53- wild-type MCL, including high-risk cases. We confirmed that sequential MRD assessment is a powerful prognostic tool in patients with MCL.

Universal germline genetic testing in patients with hematologic malignancies using DNA isolated from nail clippings.

Not available.

Proteogenomic Profiling of High-Grade B-Cell Lymphoma With 11q Aberrations and Burkitt Lymphoma Reveals Lymphoid Enhancer Binding Factor 1 as a Novel Biomarker.

High-grade B-cell lymphomas with 11q aberrations (HGBL-11q) represent a World Health Organization-defined group of lymphomas that harbor recurrent chromosome 11q aberrations involving proximal gains and telomeric losses. Although a limited number of HGBL-11q cases evaluated thus far appear to show a similar course and prognosis as Burkitt lymphoma (BL), many molecular differences have been appreciated, most notably the absence of MYC rearrangement. Despite biological differences between BL and HGBL-11q, histomorphologic and immunophenotypic distinction remains challenging. Here, we provide a comparative whole proteomic profile of BL- and HGBL-11q-derived cell lines, identifying numerous shared and differentially expressed proteins. Transcriptome profiling performed on paraffin-embedded tissue samples from primary BL and HGBL-11q lymphomas was additionally performed to provide further molecular characterization. Overlap of proteomic and transcriptomic data sets identified several potential novel biomarkers of HGBL-11q, including diminished lymphoid enhancer-binding factor 1 expression, which was validated by immunohistochemistry staining in a cohort of 23 cases. Altogether, these findings provide a comprehensive multimodal and comparative molecular profiling of BL and HGBL-11q and suggest the use of enhancer-binding factor 1 as an immunohistochemistry target to distinguish between these aggressive lymphomas.

A novel case of cutaneous myxoid spindle cell neoplasm with FMR1-ALK gene fusion and CD34/S100 co-expression.

A novel class of superficial CD34+ and S100+ cutaneous spindle cell neoplasm harboring ALK rearrangements has recently been described. Morphologically, these neoplasms have been characterized by bland spindled cells organized in whorls and cords against myxoid stroma, eventuating in the designation "superficial ALK-rearranged myxoid spindle cell neoplasm." Here, we report a 78-year-old male with a 3-mm pink papule on the chest, clinically concerning for cutaneous carcinoma. Biopsy of the specimen showed a biphasic tumor with hypercellular and hypocellular zones consisting of epithelioid cells and monomorphic, bland spindled cells. The spindled cells were arranged in perineurial-like concentric whorls and cords embedded in a myxo-collagenous stroma. Neoplastic cells were diffusely positive for CD34, S100, and D5F3-ALK, without SOX10 expression. Negative markers included GLUT1, EMA, factor XIIIa, desmin, actin, and SMA. ALK-rearrangement was identified on fluorescence in situ hybridization break-apart assay. A corresponding novel FMR1-ALK fusion was found by next-generation sequencing (NGS) based RNA sequencing. Identification of this new FMR1-ALK fusion signature adds to the spectrum of diagnostic genomic alterations in this newly described class of tumors.

Rare and novel RUNX1 fusions in myeloid neoplasms: A single-institute experience.

Chromosome translocations involving the RUNX1 gene at 21q22 are recurring abnormalities in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), that is, t(8;21) and t(3;21) and in B-cell acute lymphoblastic leukemia with t(12;21). These translocations result in the fusion of RUNX1 with RUNX1T1, MECOM, and ETV6, respectively, and are implicated in leukemogenesis. Here we describe 10 rare RUNX1 fusion gene partners, including six novel fusions, in myeloid neoplasia. Comprehensive molecular testing revealed the partner genes and features of these fusions in all the tested patients, and detected various recurring myeloid related gene mutations in eight patients. In two patients, RUNX1 mutations were identified. Most of these fusions were detected in patients with high-grade MDS and AML with a relatively short survival. Integration of conventional chromosome analysis, FISH testing and molecular genetic studies allow a comprehensive characterization of these rare RUNX1 fusions. Our study may help define myeloid neoplasms with rare and novel RUNX1 translocations and support appropriate patient management.

Mate pair sequencing improves detection of genomic abnormalities in acute myeloid leukemia.

OBJECTIVE: Acute myeloid leukemia (AML) can be subtyped based on recurrent cytogenetic and molecular genetic abnormalities with diagnostic and prognostic significance. Although cytogenetic characterization classically involves conventional chromosome and/or fluorescence in situ hybridization (FISH) assays, limitations of these techniques include poor resolution and the inability to precisely identify breakpoints. METHOD: We evaluated whether an NGS-based methodology that detects structural abnormalities and copy number changes using mate pair sequencing (MPseq) can enhance the diagnostic yield for patients with AML. RESULTS: Using 68 known abnormal and 20 karyotypically normal AML samples, each recurrent primary AML-specific abnormality previously identified in the abnormal samples was confirmed using MPseq. Importantly, in eight cases with abnormalities that could not be resolved by conventional cytogenetic studies, MPseq was utilized to molecularly define eight recurrent AML-fusion events. In addition, MPseq uncovered two cryptic abnormalities that were missed by conventional cytogenetic studies. Thus, MPseq improved the diagnostic yield in the detection of AML-specific structural rearrangements in 10/88 (11%) of cases analyzed. CONCLUSION: Utilization of MPseq represents a precise, molecular-based technique that can be used as an alternative to conventional cytogenetic studies for newly diagnosed AML patients with the potential to revolutionize the diagnosis of hematologic malignancies.

Copy number variant analysis using genome-wide mate-pair sequencing.

Copy number variation (CNV) is a common form of structural variation detected in human genomes, occurring as both constitutional and somatic events. Cytogenetic techniques like chromosomal microarray (CMA) are widely used in analyzing CNVs. However, CMA techniques cannot resolve the full nature of these structural variations (i.e. the orientation and location of associated breakpoint junctions) and must be combined with other cytogenetic techniques, such as karyotyping or FISH, to do so. This makes the development of a next-generation sequencing (NGS) approach capable of resolving both CNVs and breakpoint junctions desirable. Mate-pair sequencing (MPseq) is a NGS technology designed to find large structural rearrangements across the entire genome. Here we present an algorithm capable of performing copy number analysis from mate-pair sequencing data. The algorithm uses a step-wise procedure involving normalization, segmentation, and classification of the sequencing data. The segmentation technique combines both read depth and discordant mate-pair reads to increase the sensitivity and resolution of CNV calls. The method is particularly suited to MPseq, which is designed to detect breakpoint junctions at high resolution. This allows for the classification step to accurately calculate copy number levels at the relatively low read depth of MPseq. Here we compare results for a series of hematological cancer samples that were tested with CMA and MPseq. We demonstrate comparable sensitivity to the state-of-the-art CMA technology, with the benefit of improved breakpoint resolution. The algorithm provides a powerful analytical tool for the analysis of MPseq results in cancer.

Impact of RNA degradation on fusion detection by RNA-seq.

BACKGROUND: RNA-seq is a well-established method for studying the transcriptome. Popular methods for library preparation in RNA-seq such as Illumina TruSeq® RNA v2 kit use a poly-A pulldown strategy. Such methods can cause loss of coverage at the 5' end of genes, impacting the ability to detect fusions when used on degraded samples. The goal of this study was to quantify the effects RNA degradation has on fusion detection when using poly-A selected mRNA and to identify the variables involved in this process. RESULTS: Using both artificially and naturally degraded samples, we found that there is a reduced ability to detect fusions as the distance of the breakpoint from the 3' end of the gene increases. The median transcript coverage decreases exponentially as a function of the distance from the 3' end and there is a linear relationship between the coverage decay rate and the RNA integrity number (RIN). Based on these findings we developed plots that show the probability of detecting a gene fusion ("sensitivity") as a function of the distance of the fusion breakpoint from the 3' end. CONCLUSIONS: This study developed a strategy to assess the impact that RNA degradation has on the ability to detect gene fusions by RNA-seq.

Does parent of origin matter? Methylation studies should be performed on patients with multiple copies of the Prader-Willi/Angelman syndrome critical region.

Deletion of 15q11.2-q13 results in either Prader-Willi syndrome (PWS) or Angelman syndrome (AS) depending on the parent of origin. Duplication of the PWS/AS critical region (PWASCR) has also been reported in association with developmental delay and autism, and it has been shown that they also show a parent-of-origin effect. It is generally accepted that maternal duplications are pathogenic. However, there is conflicting evidence as to the pathogenicity of paternal duplications. We have identified 35 patients with gain of the PWASCR using array comparative genomic hybridization. Methylation testing was performed to determine parent of origin of the extra copies. Of the 35 cases, 22 had a supernumerary marker chromosome 15 (SMC15), 12 had a tandem duplication, and 1 had a tandem triplication. Only one patient had a paternal duplication; this patient does not have features typical of patients with maternal duplication of the PWASCR. Three of the mothers had a tandem duplication (two were paternal and one was maternal origin). While one of the two mothers with paternal duplication was noted not to have autism, the other was noted to have learning disability and depression. Based on our data, we conclude that SMC15 are almost exclusively maternal in origin and result in an abnormal phenotype. Tandem duplications/triplications are generally of maternal origin when ascertained on the basis of abnormal phenotype; however, tandem duplications of paternal origin have also been identified. Therefore, we suggest that methylation testing be performed for cases of tandem duplications/triplications since the pathogenicity of paternal gains is uncertain.

Performance of MYC, BCL2, and BCL6 break-apart FISH in small biopsies with large B-cell lymphoma: a retrospective Cytopathology Hematopathology Interinstitutional Consortium study.

Introduction: Fluorescence in situ hybridization (FISH) is an essential ancillary study used to identify clinically aggressive subsets of large B-cell lymphomas that have MYC, BCL2, or BCL6 rearrangements. Small-volume biopsies such as fine needle aspiration biopsy (FNAB) and core needle biopsy (CNB) are increasingly used to diagnose lymphoma and obtain material for ancillary studies such as FISH. However, the performance of FISH in small biopsies has not been thoroughly evaluated or compared to surgical biopsies. Methods: We describe the results of MYC, BCL2, and BCL6 FISH in a series of 222 biopsy specimens, including FNAB with cell blocks, CNBs, and surgical excisional or incisional biopsies from 208 unique patients aggregated from 6 academic medical centers. A subset of patients had FNAB followed by a surgical biopsy (either CNB or excisional biopsy) obtained from the same or contiguous anatomic site as part of the same clinical workup; FISH results were compared for these paired specimens. Results: FISH had a low hybridization failure rate of around 1% across all specimen types. FISH identified concurrent MYC and BCL2 rearrangements in 20 of 197 (10%) specimens and concurrent MYC and BCL6 rearrangements in 3 of 182 (1.6%) specimens. The paired FNAB and surgical biopsy specimens did not show any discrepancies for MYC or BCL2 FISH; of the 17 patients with 34 paired cytology and surgical specimens, only 2 of the 49 FISH probes compared (4% of all comparisons) showed any discrepancy and both were at the BCL6 locus. One discrepancy was due to necrosis of the CNB specimen causing a false negative BCL6 FISH result when compared to the FNAB cell block that demonstrated a BCL6 rearrangement. Discussion: FISH showed a similar hybridization failure rate in all biopsy types. Ultimately, MYC, BCL2, or BCL6 FISH showed 96% concordance when compared across paired cytology and surgical specimens, suggesting FNAB with cell block is equivalent to other biopsy alternatives for evaluation of DLBCL or HGBCL FISH testing.

Highly sensitive single tube B-lymphoblastic leukemia/lymphoma minimal/measurable residual disease test robust to surface antigen directed therapy.

BACKGROUND: Measurement of minimal/measurable residual disease (MRD) in B-lymphoblastic leukemia/lymphoma (B-ALL) has become a routine clinical evaluation tool and remains the strongest predictor of treatment outcome. In recent years, new targeted anti-CD19 and anti-CD22 antibody-based and cellular therapies have revolutionized the treatment of the high-risk B-ALL. The new treatments raise challenges for diagnostic flow cytometry, which relies on the presence of specific surface antigens to identify the population of interest. So far, reported flow cytometry-based assays are developed to either achieve a deeper MRD level or to accommodate the loss of surface antigens post-target therapies, but not both. METHODS: We developed a single tube flow cytometry assay (14-color-16-parameters). The method was validated using 94 clinical samples as well as spike-in and replicate experiments. RESULTS: The assay was well suited for monitoring response to targeted therapies and reached a sensitivity below 10-5 with acceptable precision (coefficient of variation < 20%), accuracy, and interobserver variability (κ = 1). CONCLUSIONS: The assay allows for sensitive disease detection of B-ALL MRD independent of CD19 and CD22 expression and allows uniform analysis of samples regardless of anti-CD19 and CD22 therapy.

TP53 mutations identify high-risk events for peripheral T-cell lymphoma treated with CHOP-based chemotherapy.

Nodal peripheral T-cell lymphomas (PTCL), the most common PTCLs, are generally treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based curative-intent chemotherapy. Recent molecular data have assisted in prognosticating these PTCLs, but most reports lack detailed baseline clinical characteristics and treatment courses. We retrospectively evaluated cases of PTCL treated with CHOP-based chemotherapy that had tumors sequenced by the Memorial Sloan Kettering Integrated Mutational Profiling of Actionable Cancer Targets next-generation sequencing panel to identify variables correlating with inferior survival. We identified 132 patients who met these criteria. Clinical factors correlating with an increased risk of progression (by multivariate analysis) included advanced-stage disease and bone marrow involvement. The only somatic genetic aberrancies correlating with inferior progression-free survival (PFS) were TP53 mutations and TP53/17p deletions. PFS remained inferior when stratifying by TP53 mutation status, with a median PFS of 4.5 months for PTCL with a TP53 mutation (n = 21) vs 10.5 months for PTCL without a TP53 mutation (n = 111). No TP53 aberrancy correlated with inferior overall survival (OS). Although rare (n = 9), CDKN2A-deleted PTCL correlated with inferior OS, with a median of 17.6 months vs 56.7 months for patients without CDKN2A deletions. This retrospective study suggests that patients with PTCL with TP53 mutations experience inferior PFS when treated with curative-intent chemotherapy, warranting prospective confirmation.

Enhanced clinical assessment of hematologic malignancies through routine paired tumor and normal sequencing.

Genomic profiling of hematologic malignancies has augmented our understanding of variants that contribute to disease pathogenesis and supported development of prognostic models that inform disease management in the clinic. Tumor only sequencing assays are limited in their ability to identify definitive somatic variants, which can lead to ambiguity in clinical reporting and patient management. Here, we describe the MSK-IMPACT Heme cohort, a comprehensive data set of somatic alterations from paired tumor and normal DNA using a hybridization capture-based next generation sequencing platform. We highlight patterns of mutations, copy number alterations, and mutation signatures in a broad set of myeloid and lymphoid neoplasms. We also demonstrate the power of appropriate matching to make definitive somatic calls, including in patients who have undergone allogeneic stem cell transplant. We expect that this resource will further spur research into the pathobiology and clinical utility of clinical sequencing for patients with hematologic neoplasms.

Diagnostic yield and clinical relevance of expanded genetic testing for cancer patients.

BACKGROUND: Genetic testing (GT) for hereditary cancer predisposition is traditionally performed on selected genes based on established guidelines for each cancer type. Recently, expanded GT (eGT) using large hereditary cancer gene panels uncovered hereditary predisposition in a greater proportion of patients than previously anticipated. We sought to define the diagnostic yield of eGT and its clinical relevance in a broad cancer patient population over a 5-year period. METHODS: A total of 17,523 cancer patients with a broad range of solid tumors, who received eGT at Memorial Sloan Kettering Cancer Center between July 2015 to April 2020, were included in the study. The patients were unselected for current GT criteria such as cancer type, age of onset, and/or family history of disease. The diagnostic yield of eGT was determined for each cancer type. For 9187 patients with five common cancer types frequently interrogated for hereditary predisposition (breast, colorectal, ovarian, pancreatic, and prostate cancer), the rate of pathogenic/likely pathogenic (P/LP) variants in genes that have been associated with each cancer type was analyzed. The clinical implications of additional findings in genes not known to be associated with a patients' cancer type were investigated. RESULTS: 16.7% of patients in a broad cancer cohort had P/LP variants in hereditary cancer predisposition genes identified by eGT. The diagnostic yield of eGT in patients with breast, colorectal, ovarian, pancreatic, and prostate cancer was 17.5%, 15.3%, 24.2%, 19.4%, and 15.9%, respectively. Additionally, 8% of the patients with five common cancers had P/LP variants in genes not known to be associated with the patient's current cancer type, with 0.8% of them having such a variant that confers a high risk for another cancer type. Analysis of clinical and family histories revealed that 74% of patients with variants in genes not associated with their current cancer type but which conferred a high risk for another cancer did not meet the current GT criteria for the genes harboring these variants. One or more variants of uncertain significance were identified in 57% of the patients. CONCLUSIONS: Compared to targeted testing approaches, eGT can increase the yield of detection of hereditary cancer predisposition in patients with a range of tumors, allowing opportunities for enhanced surveillance and intervention. The benefits of performing eGT should be weighed against the added number of VUSs identified with this approach.

Radiation-induced epigenetic alterations after low and high LET irradiations.

Epigenetics, including DNA methylation and microRNA (miRNA) expression, could be the missing link in understanding radiation-induced genomic instability (RIGI). This study tests the hypothesis that irradiation induces epigenetic aberrations, which could eventually lead to RIGI, and that the epigenetic aberrations induced by low linear energy transfer (LET) irradiation are different than those induced by high LET irradiations. GM10115 cells were irradiated with low LET X-rays and high LET iron (Fe) ions and evaluated for DNA damage, cell survival and chromosomal instability. The cells were also evaluated for specific locus methylation of nuclear factor-kappa B (NFκB), tumor suppressor in lung cancer 1 (TSLC1) and cadherin 1 (CDH1) gene promoter regions, long interspersed nuclear element 1 (LINE-1) and Alu repeat element methylation, CpG and non-CpG global methylation and miRNA expression levels. Irradiated cells showed increased micronucleus induction and cell killing immediately following exposure, but were chromosomally stable at delayed times post-irradiation. At this same delayed time, alterations in repeat element and global DNA methylation and miRNA expression were observed. Analyses of DNA methylation predominantly showed hypomethylation, however hypermethylation was also observed. We demonstrate that miRNA expression levels can be altered after X-ray irradiation and that these miRNA are involved in chromatin remodeling and DNA methylation. A higher incidence of epigenetic changes was observed after exposure to X-rays than Fe ions even though Fe ions elicited more chromosomal damage and cell killing. This distinction is apparent at miRNA analyses at which only three miRNA involved in two major pathways were altered after high LET irradiations while six miRNA involved in five major pathways were altered after low LET irradiations. This study also shows that the irradiated cells acquire epigenetic changes suggesting that epigenetic aberrations may arise in the cell without initiating chromosomal instability.