Location of the t(4;14) Translocation Breakpoint Identifies a Subset of Newly-Diagnosed Multiple Myeloma Patients with Poor Prognosis

Introduction: The recombination of chromosomes 4 and 14 (t(4;14)) is a primary, predominantly clonal event in newly diagnosed multiple myeloma (ndMM) that is present in ~15% of patients. The translocation results in enhancer regions from the immunoglobulin heavy chain locus upregulating the expression of NSD2 and FGFR3 genes implicated in the disease biology of this subset of MM patients (Chesi et al. Blood. 1998, Keats et al, Leuk Lymph. 2006). The presence of t(4;14) translocation is a considered a biomarker of aggressive disease and is part of the Revised International Staging System (R-ISS) for clinical risk stratification. However, historically only ~40% of t(4;14) patients are high-risk based on the GEP70 gene expression signature. (Weinhold et al. Leukemia. 2016) Our previous analysis of a large cohort of ndMM patients described the genomic features of t(4;14) vs ndMM overall population demonstrating that only ~25% of t(4;14) patients died within 24 months of diagnosis and described biomarkers in this high-risk subset. This analysis identified both known and novel aberrations in ndMM, including some that were associated with high-risk t(4;14) (Ortiz et al Blood. 2019; 134 (Suppl_1):366). In this updated analysis, we provide a more robust analysis of the t(4;14) dataset and demonstrate the prognostic value of the NSD2 breakpoint location. Methods: We generated a large genomic dataset from t(4;14) ndMM patients with whole genome sequencing (WGS) and RNA-seq from a TOUL dataset (t(4;14) N=114) patients treated in routine practice), the IFM2009 trial (N=19), and the Myeloma Genome Project (MGP) (N=34) for discovery and validation. Gene expression, copy number aberration, single nucleotide variant and translocations were derived from RNAseq and WGS profiling of biopsies from patients aged less than 75 years who received transplant, and integrated with clinical information (including age, OS). Cytogenetic assessments from WGS were made by MANTA and used to identify translocation DNA breakpoint location. Results: In all datasets, three DNA breakpoint locations were identified, and based on their position with respect to the NSD2 gene named "no-disruption" (upstream of NSD2 gene), "early-disruption" (in the 5' UTR of NSD2 gene) and "late-disruption" (in the coding region of NSD2 gene). Using paired RNA-seq data, we identified IGH-NSD2 RNA fusion transcripts relative to the breakpoints that corresponded with previously described NSD2 isoforms. "No-disruption" and "early-disruption" breakpoints predominantly produced a fusion transcript (MB4-1) that retained the full coding sequence of the gene, while the "late-disruption" produced truncated fusion transcripts (MB4-2/3). We conducted survival analysis in our datasets based on both DNA breakpoint location and RNA fusion transcripts. This analysis demonstrated a significant difference in outcome between the patient samples with "no-disruption" and the "late-disruption" breakpoints that associated with good and poor OS, respectively (OS pval < 3e-4) in the discovery TOUL dataset. Patients with "late-disruption" had a median OS of 28.64 mo vs 59.18 mo for "early disruption" and 82.26 mo for those with "no disruption" (Figure). This association was replicated in an independent dataset (MGP N=33, replication pval<4.3e-5). The mOS difference of patients based on which fusion transcript they express is less than the difference based on breakpoint (mOS MB4-1 = 47.38 mo. vs. MB4-2/3 = 60.89 mo.). These analyses demonstrate that the breakpoint location has a stronger association with outcome than fusion transcript expression. Conclusion: From a large genomic dataset, we were able to discover and validate a clear association between the translocation breakpoints and survival outcome in t(4:14) ndMM patients. While prospective validation is needed before clinical application of our finding, molecular identification of high-risk t(4;14) patients using DNA breakpoint location may enable proper risk classification for this patient group at diagnosis, and would provide improved opportunities for risk-adjusted therapy and identification of a therapeutic target for this high-risk subpopulation. Ongoing work on mutations, copy number, and differential gene expression analyses between translocation breakpoint sub-groups and will be presented. Figure 1 Figure 1. Disclosures Stong: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Ortiz: Bristol Myers Squibb: Current Employment. Towfic: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Pierceall: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Flynt: Bristol Myers Squibb: Current Employment. Thakurta: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties.

A novel NCOR2-NTRK1 fusion detected in a patient of lung adenocarcinoma and response to larotrectinib: a case report

Background The identification of NTRK fusions in tumours has become critically important due to the actionable events predictive of response to TRK inhibitor. It is not clear whether the NTRK breakpoint location is different for response to targeted therapy and NTRK fusions affects the efficacy of immunotherapy. Case presentation Here we reported a 60-year-old female diagnosed with advanced lung adenocarcinoma. NGS-based molecular profiling identified a novel NCOR2-NTRK1 fusion and high tumor mutational burden (TMB) (58.58 mutations/Mb) in this case. Additionally, program death-ligand 1 (PD-L1) expression was detected in 20–30% of the tumor cells by immunohistochemical (IHC) staining. The patient received treatment with anti-PD-1 immune checkpoint inhibitor of camrelizumab. After two cycles of treatment, the CT scan showed some tumor nodules were still enlarged, indicating disease progression. She was then changed to TRK inhibitor larotrectinib. One month later, the CT scan showed the volume of some lesions started to decrease, and no metastasis lesions were found. The patient then continued the administration of larotrectinib, and some lesion sizes were significantly reduced or even disappeared in the next few months. Currently, this patient is still alive. Conclusions Altogether, this report provided a new driver of lung adenocarcinoma expanded the mutational spectrum of NTRK1 fusion variants and suggested using larotrectinib as the targeted therapy is more effective than anti-PD-1 inhibitor in lung adenocarcinoma harboring with NTRK fusion, positive PD-L1 expression, and high TMB simultaneously.

Pervasive and non-random recombination in near full-length HIV genomes from Uganda

Recombination is an important feature of HIV evolution, occurring both within and between the major branches of diversity (subtypes). The Ugandan epidemic is primarily composed of two subtypes, A1 and D, that have been co-circulating for 50 years, frequently recombining in dually infected patients. Here, we investigate the frequency of recombinants in this population and the location of breakpoints along the genome. As part of the PANGEA-HIV consortium, 1,472 consensus genome sequences over 5 kb have been obtained from 1,857 samples collected by the MRC/UVRI & LSHTM Research unit in Uganda, 465 (31.6 per cent) of which were near full-length sequences (>8 kb). Using the subtyping tool SCUEAL, we find that of the near full-length dataset, 233 (50.1 per cent) genomes contained only one subtype, 30.8 per cent A1 (n = 143), 17.6 per cent D (n = 82), and 1.7 per cent C (n = 8), while 49.9 per cent (n = 232) contained more than one subtype (including A1/D (n = 164), A1/C (n = 13), C/D (n = 9); A1/C/D (n = 13), and 33 complex types). K-means clustering of the recombinant A1/D genomes revealed a section of envelope (C2gp120-TMgp41) is often inherited intact, whilst a generalized linear model was used to demonstrate significantly fewer breakpoints in the gag–pol and envelope C2-TM regions compared with accessory gene regions. Despite similar recombination patterns in many recombinants, no clearly supported circulating recombinant form (CRF) was found, there was limited evidence of the transmission of breakpoints, and the vast majority (153/164; 93 per cent) of the A1/D recombinants appear to be unique recombinant forms. Thus, recombination is pervasive with clear biases in breakpoint location, but CRFs are not a significant feature, characteristic of a complex, and diverse epidemic.

High-resolution architecture and partner genes of MYC rearrangements in lymphoma with DLBCL morphology

Genomic rearrangements in the MYC locus occur in ∼12% of lymphomas with diffuse large B-cell lymphoma (DLBCL) morphology and are associated with inferior outcome. Previous studies exploring MYC rearrangements have primarily used fluorescence in situ hybridization (FISH) assays to characterize break-apart status but have rarely examined breakpoint location, and in some cases have not examined partner identity. We performed targeted sequencing of MYC, BCL2, BCL6, and the immunoglobulin (IG) loci in 112 tumors with DLBCL morphology harboring MYC rearrangement. We characterized the location of the MYC rearrangement at base pair resolution and identified the partner in 88 cases. We observed a cluster of breakpoints upstream of the MYC coding region and in intron 1 (the “genic cluster”). Genic cluster rearrangements were enriched for translocations involving IGH (80%), whereas nongenic rearrangements occurred mostly downstream of the MYC gene with a variety of partners, including IGL and IGK. Other recurrent partners included BCL6, ZCCHC7, and RFTN1, which has not previously been described as a MYC partner. We compared 2 commercially available FISH break-apart assays for the MYC locus and observed discordant results in 32% of cases examined, including some with MYC-IGL and MYC-IGK rearrangements. In cases of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement (HGBL-DH), so-called “double-hit” lymphomas, the majority of MYC rearrangements had non-IG partners (65%), with breakpoints outside the genic cluster (72%). In patients with de novo HGBL-DH of DLBCL morphology, MYC-IG rearrangements showed a trend toward inferior time to progression and overall survival compared with MYC–non-IG rearrangements. Our data reveal clinically relevant architecture of MYC rearrangements in lymphomas with DLBCL morphology.

The Effects of Capital Flows on Economic Growth in Senegal

This article examines the effects of capital flows on economic growth in Senegal using autoregressive distributed lag (ARDL) over the period 1970–2014. Overall, our results show that remittances cause economic growth in Senegal in the long run. In contrast, external debt has a negative impact on economic growth. The ARDL results, however, show no cointegration between aid and growth or between foreign direct investment (FDI) and growth. The Quandt–Andrews breakpoint test selects year 1991 as the most likely breakpoint location for the remittances–growth equation. Finally, time-varying parameter analyses using the year 1991 as a slope dummy reveal that remittances have been growth-enhancing post-1991. Therefore, government and policy makers in Senegal must create a favourable atmosphere for attracting more remittances to promote economic development. JEL: F21, F24, F35, F34, O10

MLL genomic DNA Breakpoints In Infant Acute Leukemia

Background Infant acute leukemia is characterized by high incidence of MLL gene rearrangements. Purpose To evaluate the distribution of MLL genomic DNA breakpoints and their relation to several diagnostic parameters among infant acute leukemia. Methods 72 infants with MLL-rearranged acute lymphoblastic leukemia (ALL) (n=52), acute myeloid leukemia (AML) (n=19) and mixed phenotype acute leukemia (n=1) were included in this study based on the availability of DNA material at diagnosis. In the observed group there were 28 boys (39%) and 44 girls (61%) with median age of 4.9 mo (range 0.03-11.9). Genomic DNA breakpoint detection in MLL gene and translocation partner genes (TPG) was performed by long-distance inverse PCR (LDI-PCR). Exon-intron numbering of MLL gene was done according to I. Nilson et al, 1996. Results Majority of ALL cases (n=28; 54%) was characterized by presence of MLL-AF4 fusion gene (FG), less frequently MLL-MLLT1 (n=12; 23%), MLL-MLLT3 (n=7; 13%) and others were found (Table 1). The most common breakpoint location within MLL gene in ALL patients was intron 11, detected in 25 cases (48%). The highest variability of MLL breakpoints was found in MLL-AF4-positive patients: only 11 of 28 (39%) had breakpoints in intron 11. The most stable pattern of MLL genomic DNA breakpoints was observed in MLL-MLLT1-positive patients: 8 of 12 (67%) had breakpoints in intron 11. In AML patients two the most prevalent FGs were MLL-MLLT3 (n=7, 37%) and MLL-MLLT10 (n=5, 26%). The remaining ones are listed in Table 1. The most frequent breakpoints location was intron 8 (8 out of 19, 42%). The most stable pattern was revealed for MLL-MLLT10 FG: MLL breakpoints in 4 of 5 (80%) cases were found in intron 9 (Table 1). ALL patients who had breakpoints in intron 11 were significantly younger (median 3.0 mo, range 0.03-11.6) than all others (median 5.6 mo, range 0.7-11.9) (p=0.025) and than patients with MLL breakpoints in intron 9 (median 6.6 mo, range 3.1-11.9) (p=0.017). For AML cases we did not find any relation between age and breakpoints locations. Distribution of MLL DNA breakpoints was similar in boys and girls and did not depend on type of TPG. Genetic recombinations involving MLL gene predominantly resulted in reciprocal chromosomal translocations (n=62; 86%). Beside them, 6 (11%) insertions were identified in all MLL-MLLT10-positive cases and MLL-SEPT6-positive one. In 11 (15%) patients we found breakpoints within the regions located from 0.7 Kb to 25.4 Kb 3' of the first exon of TPGs (MLLT1 n=9; EPS15 n=1; MYO1F n=1), however fusion transcripts at cDNA level were identified and sequenced in all these cases, indicating a spliced fusion mechanism. 3-way translocations were found in 5 patients and in 1 case we found combination of insertion with interstitial deletion of chromosome 11. The list of reciprocal genes involved in these 6 cases was as follows: CEP164, DNAH6, DCPA1, MCL1 as well as non-coding regions of 2q21.2 and 2p21. We also analyzed breakpoints in TPGs. Except above mentioned spliced fusion cases, the remaining 3 breakpoints in MLLT1 as well as 3 of 4 breakpoints in EPS15 and all breakpoints in MLLT11 were within intron 1 of corresponding genes. In AF4 the major breakpoint region included intron 3 (n=19), intron 4 (n=6) and intron 5 (n=2). We also revealed 2 rare breakpoints in intron 6 and 10. In MLLT3 the most frequent breakpoint location was intron 5 (n=12), additionally 2 cases in intron 5 were identified. In MLLT10 two separate breakpoint locations were found: intron 3 (n=1) and intron 8 (n=3) in combination with intron 9 (n=1). We estimated prognostic significance of MLL breakpoint locations in 31 cases of infant ALL treated by MLL-Baby protocol. 3-year cumulative incidence of relapse was remarkably higher in patients with breakpoints in intron 11 (n=18) in comparison to patients with breakpoint localized from intron 7 to exon 11, inclusively (n=13) (0.85±0.01 and 0.57±0.02, respectively), although difference between these two groups did not achieve statistical significance (p=0.261). Median follow-up time in the observed group was 30 months (range 6–42). Conclusion In the current study we estimated clinical and prognostic significance of MLL and TPG genomic DNA breakpoints in infant acute leukemia. Our data provide additional information of molecular genetic features of MLL-rearranged infant acute leukemia. Disclosures: No relevant conflicts of interest to declare.

MLL Gene Rearrangements in 174 Infants with Acute Leukemia.

Abstract 2537 Background. MLL gene rearrangements are the most common genetic events in infant leukemia. Up to date more than 100 various MLL rearrangements were described. Purpose. To evaluate the distribution of MLL rearrangements among infants (aged from 1 to 365 days) with both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Methods. 174 infants (117 ALL and 57 AML cases) were included in the current study. 11q23/MLL rearrangements were detected by chromosome banding analysis (CBA), fluorescence in-situ hybridization (FISH) and reverse-transcriptase PCR (RT-PCR). CBA was done according to standard procedure. FISH analysis using LSI MLL Dual Color, Break Apart Rearrangement Probe (Abbott Molecular, USA) was performed on at least 200 interphase nuclei and on all available metaphases. RT-PCR was performed as previously described (A. Borkhardt et al.,1994, N. Palisgaard et al., 1998, J. van Dongen et al., 1999). In 39 cases genomic DNA breakpoint was detected in MLL and translocation partner genes by long-distance inverse PCR (LDI-PCR). Exon-intron numbering of MLL gene was done according to I. Nilson et al, 1996. Results. 11q23/MLL rearrangements were revealed in 74 ALL patients (63.2%). Among this group MLL-AF4 was detected in the majority of cases (53.5%), less frequently were found MLL-MLLT1, MLL-MLLT3, MLL-MLLT10 and others (fig. 1a). Children with ALL under 6 months of age had significantly higher incidence of MLL rearrangements in comparison with older infants (84.0% vs. 47.8%, p<0.001). MLL-positive patients more frequently had BI-ALL and less frequently BII-ALL than infants without these rearrangements (p<0.001 for both). Fusion gene transcripts were sequenced in 26 MLL-rearranged ALL cases. Depending on breakpoint position within MLL and partner genes we detected 7 different types of MLL-AF4 fusion gene transcript, 3 types of MLL-MLLT1, 2 types of MLL-EPS15. The most common fusion site within MLL gene in ALL patients was exon 11, detected in 14 cases (53.8%). It was confirmed by LDI-PCR, that in addition to common breakpoint location in MLL gene (18 out of 27 cases in intron 11, 4 cases in intron 9) allowed to reveal less frequent breakpoint sites, like intron 12 (1 case), intron 10 (3 cases) and intron 7 (1 case). Interestingly, in the last case where LDI-PCR showed presence of MLL-AF4, this fusion gene transcript was not initially found by RT-PCR, because applied primer set did not cover exon 7. Moreover, due to lack of metaphases this patient was primary misclassified as MLL-rearranged, but MLL-AF4-negative. MLL rearrangements were found in 28 AML cases (49.1%). In AML patients the most common MLL rearrangements were MLL-MLLT10 (32% of cases) and MLL-MLLT3 (28%). Other ones were detected less frequently (fig. 1b). In AML patients frequency of MLL rearrangements was similar in children younger and older than 6 months (p=0.904). Among MLL-positive cases AML M5 were detected significantly more often and AML M7 significantly less frequent than in MLL-negative patients (p=0.024 and p=0.001, correspondingly). The most common breakpoint location within MLL gene in AML patients was intron 9, detected in 6 out of 12 cases (50%). Additional chromosomal abnormalities were revealed in 7 out of 21 MLL-positive AML patients with known karyotype (33%), while complex karyotype was detected in 5 cases (24%). Application of LDI-PCR allowed to verify rare MLL rearrangements, including MLL-AFF3 (1 ALL case), MLL-MYO1F (2 AML cases), MLL-SEPT6 (1 AML case), MLL-SEPT9 (1 AML case) In 4 ALL and 3 AML patients MLL rearrangements with concurrent 3'-deletion of MLL gene were found. 3'-deletion of MLL was not associated with breakpoint position in MLL gene and type of translocation partner gene. None of the patients with 3'-deletions had reciprocal fusion gene. Based on LDI-PCR data we assessed several mechanisms of fusion gene formation. Reciprocal translocations were detected in 29 cases, 3-way translocations in 3 cases, inversions in 5 cases, combination of inversion and insertion in 2 cases. Conclusion. In the current study we precisely characterized large cohort of MLL-rearranged infant acute leukemia patients. Combination of all available techniques, including cytogenetics, FISH, RT-PCR and LDI-PCR can lead to detailed verification of every single MLL rearrangement. Disclosures: No relevant conflicts of interest to declare.