Abstract: Background: Genetic information has become critical to understand the development of T-cell acute lymphoblastic leukemia (T-ALL) and to elucidate the origin of disease relapse. Several genetic markers, together with measurable residual disease (MRD), are considered strong predictors of patient outcome. However, the prognostic significance of genetic markers can varie according to treatment. Aim: We used targeted deep sequencing to analyze the genetic profile of 125 T-ALL patients enrolled in three consecutive MRD-oriented trials from the Spanish PETHEMA (Programa Español de Tratamientos en Hematología) group. Genomic information was analyzed together with the main clinical and biologic data in a subset of 111 patients with detailed clinical and outcome data to determine the prognostic significance for overall survival (OS) and cumulative incidence of relapse (CIR). Methods: Genetic mutations were detected using a custom gene panel and sequenced on a MiSeq platform. Alignment, variant calling, filtration and annotation of variants were done using standardized pipelines. OS curves were plotted by the Kaplan-Meier method and compared by the log-rank test. CIR was estimated using cumulative incidence functions by competing risks analysis. A Cox proportional hazard regression model was used to identify predictive factors for OS. Statistical significance was set at (two-sided) p-values & lt;0.05. Results: Recurrently mutated genes found in ≥4/125 patients involved transcription factor tumor suppressor genes (PTEN, BCL11B, RUNX1, GATA3, ETV6), epigenetic regulators (PHF6, DNMT3A, EP300, KMT2C, EZH2, TET2), DNA mismatch repair genes (MSH2), ribosomal (RPL5) and RNA splicing (U2AF1) genes, and genes involved in the RAS/MAPK (NRAS), WNT (FAT1, FAT3), IL7R-JAK-STAT (JAK3, JAK1, IL7R) and NOTCH1 signaling pathways, respectively. Mutations in the latest pathway (NOTCH1 & FBXW7) was found in 88/125 (70%) patients. Clinical-genetic correlations revealed that patients with mutations in JAK3, DNMT3A, N/KRAS, IL7R, MSH2 or in U2AF1 were associated with lower OS (vs unmutated patients). None of the mutated genes had impact on CIR. Upon grouping the mutated genes according to their functional role and potential biological impact on T-ALL, two gene signatures were defined. These included the aging gene signature (DNMT3A and U2AF1) characterized by mutations in genes identified in clonal hematopoiesis of indeterminate potential (CHIP); and the treatment resistance gene signature (JAK3, N/KRAS, IL7R and MSH2), defined by mutations in genes involved in resistance to the ALL therapy. Both clusters identified patients with poorer response to therapy (poorer blast clearance on day 14 of induction treatment and lower CR rates). Therefore, we considered together (worse outcome genetics [WOG] signature) for univariate and multivariate analyses. WOG and MRD level (0.1% cut-off) on day 35 after induction therapy (+35d MRD) showed significant prognostic impact in the univariable and multivariable analyses for OS (3y) with a hazard ratio (95% CI) of 2.4 (1.2; 4.8) and 2.7 (1.4; 5.1), respectively (Table 1). OS according to these two variables allowed risk stratification of T-ALL into low, intermediate- and high-risk (HR) patients with significantly different outcomes (p & lt;0.001) (Figure 1). Conclusion: A genetic signature with independent prognostic significance of MRD has been identified in this cohort of patients included in MRD-oriented trials. This gene signature (WOG) together with MRD could help to improve risk-stratification of adult T-ALL patients and would be of interest in the search for new therapies for HR patients Funding: Support from AECC (GC16173697BIGA); ISCIII (PI19/01828 and PI19/01183), co-funded by ERDF/ESF, "A way to make Europe"/"Investing in your future", CERCA/Generalitat de Catalunya SGR 2017 288 (GRC)/ C González-Gil was supported by AGAUR grant (2020 FI_B2 00210). Figure 1 Figure 1. Disclosures Diaz-Beyá: Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mercadal: Gilead Sciences, Inc.: Honoraria, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Tormo: Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Barba: Amgen, Celgene, Gilead, Incyte, Jazz Pharmaceuticals, MSD, Novartis, Pfizer and Roche, Jazz Phar,aceuticals: Honoraria; Cqrlos III heqlth Institute, aSOCIACION espanola contra el cancer, PERIS: Research Funding. Maciejewski: Regeneron: Consultancy; Novartis: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Alexion: Consultancy. Ribera: ARIAD: Consultancy, Research Funding, Speakers Bureau; AMGEN: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; TAKEDA: Consultancy, Research Funding, Speakers Bureau; NOVARTIS: Consultancy, Speakers Bureau; SHIRE: Consultancy, Speakers Bureau.

Abstract: Introduction The inherited platelet disorders (IPD) are a heterogeneous group of rare diseases including quantitative and/or qualitative platelet defects. Classically, patients with IPD are first functionally tested to know the possible defect before sequencing a single or a few genes. Phenotipyc diagnostic of IPD often requires light transmission aggregometry, quantitative analysis of receptors by flow cytometry and fluorescence and electron microscopy. This diagnostic strategy is complex, poorly standardised and time consuming. In addition, the phenotype can seldom guide the singles candidates genes for conventional Sanger squencing. Therefore, many patients remain without a accurate diagnosis of their IPD. Next generation sequencing (NGS) enables the simultaneous analysis of large groups of candidate genes in IPD and may be useful for rapid genetic diagnosis. The aim of this study was to design and validate a NGS panel for IPD. Patients & Methods We describe a strategy for rapid genetic diagnosis of IPD with Illumina sequencing of 60 candidates genes previously associated with IPD (table1). The baits were designed to tile 400 kb of gDNA sequence corresponding to the exons and splice sites in all known transcripts of the candidate genes identified. The bait library was tested by enriching the candidate IPD genes from 50 ng DNA obtained and sequencing by Nextera Rapid Custom Enrichment system. Results were analysed by Variant Studio system and Sequencing Analysis Viewer. A total of 21 patients were studied. For the validation process, DNA samples of 9 unrelated patients with IPD and their mutation known were used: two patients with Glanzmann Thrombasthenia (ITGA2B, p.Ala989Thr, p.Val982Met and p.Glu538Stop; ITGB3, p.Leu222Pro and p.Tyr216Cys), one Hermansky-Pudlak Sd. (HPS1, p.Glu204 Stop), another with Bernard-Soulier Sd. (GPIX, p.Phe71Stop), a case of Congenital Amegakaryocytic Thrombocytopenia (MPL, p.Arg102Cys), and 2 patients with Chediak Higashi Sd. (LYST, p.Gly3725Arg and p.Cys258Arg). Once validated, the NGS panel was used for genetic diagnostic of 8 patients with suspected IPD. Results Eleven mutations, previously identified in another center by conventional sequencing, were detected by our panel NGS (100% success in the validation process). We then tested this strategy for patients with suspected of IPD without diagnosis: I. a 13 years old girl with agenesis of the corpus callosum, facial dysmorphia, renal agenesis and thrombocytopenia was diagnosed of Thrombocytopenia FLNA-related and Periventricular Nodular Heterotopia (PNHV)[mutation in the FLNA was detected (p.Thr1232Ile)]. II. A two years old patient with severe thrombocytopenia and recurrent infections was diagnosed of Wiskott-Aldrich Sd (WAS, p.Arg268Gly fs Stop40). III. A patient with deafness, macrothrombocytopenia, and Döhle bodies was diagnosed by MYH9 deletion (MYH9; p.Asp1925Thr fs Stop23). IV. Six members of a family (2 of them with symptoms of mucocutaneous bleeding, and macrothrombocytopenia), in which an insertion in NBAL2 (p.Gly1142Arg fs Stop49) gene was found. Therefore, Gray Platelet Sd was diagnosed. Moreover, one patient with aspirin-like syndrome showed a P2RY12 mutation (p.Val279Met). Finally, mother and son with mild Hemophilia A (F8; p.Gln2208Arg) were detected. Conclusions This NGS panel enables a rapid genetic diagnostic of IPD. The use of NGS-based strategy is a feasible tool for the diagnosis of IPD that could be added to the screening of these disorders. Five mutations have not previously been described in the literature. Table 1: Sixty candidates' genes previously associated with IPD: Inherited Platelet Disorders Genes = 60 Cytoskeletal Assembly and Structural Proteins GP1BA, GP1BB, GP5, A2M, GP9, VWF, ITGA2, ITGA2B, ITGB3, ABCA1, ANO6,FERMT3, ACTN1, MASTL Disorders of agonist platelet receptors P2RX1, P2RY1, P2RY12, TBXA2R, TBXAS1, ADRA2A, GP6, CD36 o GP4, DTNBP1 Disorders signal transduction GNAI3, GNAQ, GNAS, PLA2G7, PLCB2PTS, GGCX, DPAGT1, DHCR24 Disorders of platelet granules NBEAL2, GFI1B, PLAU, HPS1, HPS3, HPS4, HPS5, HPS6, LYST, MLPH, BLOC1S3, BLOC1S6, AP3B1, VIPAS39, VPS33B, RAB27A, MYO5A, USF1 Thrombocytopenias and syndromes WAS, MYH9, FLNA, FLI1, STIM1, HOXA11, ANKRD26, MPL, RBM8A RUNX1, GATA1 Disclosures No relevant conflicts of interest to declare.

Abstract: From November 2014 to May 2017, 332 patients homogeneously treated with VRD induction, ASCT and VRD consolidation were randomized to receive maintenance therapy with RD (161 patients) vs IRD (171 patients). RD consisted of lenalidomide 15 mg/d from days 1-21 plus dexamethasone 20 mg/d on days 1-4 and 9-12 at 4-weeks intervals while in the IRD arm oral ixazomib at a dose of 4 mg on days 1,8, and 15 was added. MRD negative patients after 24 cycles were discontinued while those who were MRD positive remained on maintenance with RD for 36 more cycles. The MRD negativity from baseline increased from 50.9% to 71.8% with RD and from 59.6% to 72.4% with IRD at 2 years. After a median follow-up of 69 months from the initiation of maintenance, the PFS was similar in both arms, median not reached in either arm with a 6-years PFS rate of 61.3% and 55.6% for RD and IRD, respectively (HR 1.136 [95% CI 0.809 - 1.603]). No significant differences in PFS between RD and IRD were observed in any prognostic subgroup. After 2 years of maintenance, treatment was discontinued in 163 patients who were MRD negative while 63 MRD positive patients were continued on RD therapy. Maintenance discontinuation in MRD negative patients resulted in a low progression rate (17.2% at 4 years), even in patients with high-risk features. In summary, our results show the efficacy of RD maintenance and support the safety of maintenance discontinuation in MRD negative patients at 2 years. This trial is registered at ClinicalTrials.gov (NCT02406144) and EudraCT (2014-00055410).

Abstract: We have analyzed overall survival (OS-REL), progression-free survival (PFS-REL) and the clinical variables influencing the long-term outcome for patients with Hodgkin′s lymphoma (HL) who relapse after an autologous stem cell transplantation (ASCT). From 639 patients autografted for HL [383 males (60%) and 256 (40%) females, median age of 30 (1–66) years] reported to the GEL/TAMO Cooperative Group between January/1984 and January/2003, 175 patients (27%) relapsed at a median time of 10 (4 – 125) months [median (range)] after ASCT. They were 97 males (56%) and 78 (44%) females with a median age of 28 (10 – 66) [median (range)] years at transplantation. Sixty-three patients were autografted in complete remission, 73 in sensitive relapse and 31 in resistant relapse. One hundred and sixty three patients (94%) received different chemotherapy (CT) protocols as conditioning regimen and 12 patients (6%), CT plus total body irradiation. At relapse, 94 patients (53%) presented with advanced stages (III-IV), 49 patients (28%) with B symptoms and 19 (11%) with bulky disease. Relapse was extranodal in 45% of the patient population. Ten percent of the patients had a poor performance status (ECOG ≥2) and 37 patients (22%) had a hemoglobin (Hb) level 〈 100 g/l at relapse. Thirty four patients (20%) received no further therapy, 107 (60%) received different CT +/− radiotherapy and the remaining 34 patients (20%) were treated with a second stem cell transplantation (13 patients, an ASCT and 21 an allogeneic transplantation). OS-REL and PFS-REL were of 35% ± 4% and 23% ± 4% at 3 years, respectively. Advanced clinical stage (III-IV) at relapse [relative risk (RR) 4.4, 95% confidence interval (CI) (1.7 – 10.8), p = 0.002] and an interval between ASCT and relapse 〈 12 months [RR 2.4, 95%CI (1.1 – 5.0), p = 0.03] were independent adverse prognostic factors for PFS-REL. Advanced clinical stage at relapse [RR 4.4, 95%CI (1.4 – 14.4), p = 0.012] , extranodal disease [RR 2.4, 95%CI (1.3 – 15.4), p = 0.02] and a Hb level 〈 100 g/l at relapse [RR 3.4, 95%CI (2.0 – 10.4), p = 0.03] were significant adverse prognostic factors for OS-REL. Although the long-term outcome of HL patients who relapse after ASCT is poor, results are better in patients with late relapses and localized disease. Moreover, a minority of the patients can become long-term progression-free survivors after relapse. The identification and construction of prognostic sub-groups according to the number of risk factors may be useful to develop risk-adapted therapeutic strategies.

Abstract: We have analyzed the incidence and risk factors for developing a secondary malignancy (SM) in patients with Hodgkin’s lymphoma (HL) treated with an autologous stem cell transplantation (ASCT). From 639 patients autografted for HL [383 males and 256 females with a median age of 30 (1–66) years and a median follow-up after ASCT of 53 (3–202) months] reported to the GEL/TAMO Spanish Cooperative Group between January/1984 and January/2003, 37 patients (6% of the series) developed a SM at a median time of 35 months after ASCT [24 patients (65%) a myelodisplastic syndrome (MDS)/acute myelogenous leukemia (AML), 3 patients (8%) a non Hodgkin’s lymphoma (NHL) and 10 patients (29%) a solid tumor (ST)]. There were 24 males and 13 females with a median age of 39 (13–60) years [23 patients (61%), 〈 40 years] at ASCT. Twenty-three patients (62%) presented with advanced disease at diagnosis, 14 patients (38%) had B symptoms, seven (19%) bone marrow (BM) involvement and 13 (35%), bulky mediastinal disease. Eighteen patients (49%) had previously received nitrogen mustard containing therapies, eight patients (22%) had been splenectomized before ASCT and 18 (49%) had received complementary radiotherapy. Twenty patients (70%) had received more than two lines of chemotherapy (CT) before ASCT. Fourteen patients (38%) were in complete remission (CR) at ASCT, 16 patients (43%) were in chemosensitive relapse and seven in resistant relapse. In 25 patients (68%), peripheral blood was used as the source of hematopoietic stem cells and in the remaining 12 patients, BM. Only three patients received total body irradiation as part of the conditioning regimen. Time between diagnosis and ASCT was 〉 24 months in 23 patients (62%). Twenty-three patients (62%) were in CR when they developed the SM and the remaining 14 (38%), had active disease. Median time to develop a myeloid malignancy was of 12 (4 – 34) months, to develop a lymphoid malignancy (T cell NHL, 2 patients; B cell NHL, 1 patient) was of 23 (12 – 31) months and to develop a ST (2 squamous cell carcinomas of the lung, 2 rabdomisarcomas, 2 adenocarcinomas of the rectum, 1 basocelular carcinoma, 2 in situ bladder carcinoma and one oropharyngeal carcinoma) of 60 (34 – 91) months, respectively (p = 0.0001). Twenty eight patients have died: 18 patients (64%) due to the SM and 10 (36%) due to HL progression. Multivariate analysis identified age at ASCT 〉 40 years and the time between diagnosis and ASCT 〉 24 months as the only two bad prognostic factors for developing a SM [relative risk (RR) 2.48, 95% confidence interval (CI) (1.20–5.10), p = 0.01 and 2.17, 95%CI (1.06–4.46), p = 0.034], respectively. The risk of developing a SM is a real long time side effect after an autologous procedure in HL patients. Advanced age at ASCT and a long time interval between diagnosis and ASCT, a probable surrogate marker of the amount of CT given to the patient before the ASCT have been, in our experience, the only two risk factors for developing this complication.

Abstract: Chronic lymphocytic leukemia (CLL) patients harboring 11q22.3 deletion, del(11q), are characterized by a rapid disease progression. One of the suggested genes to be involved in the pathogenesis of this deletion is BIRC3, a negative regulator of NF-κB, which is monoallelically deleted in ~80% of del(11q) CLL cases. In addition, truncating mutations in the remaining allele of this gene can lead to BIRC3 biallelic inactivation, which accounts for marked reduced survival in CLL. Nevertheless, the biological mechanisms by which monoallelic or biallelic BIRC3 lesions could contribute to del(11q) CLL pathogenesis, progression and therapy response are partially unexplored. We used the CRISPR/Cas9 system to model monoallelic and biallelic BIRC3 loss in vitro. First, we generated an isogenic HG3 CLL cell line harboring monoallelic del(11q) - HG3-del(11q) - by the introduction of 2 guide RNAs targeting 11q22.1 and 11q23.3 (~17 Mb). Loss-of-function BIRC3 mutations (MUT) were introduced in the remaining allele, generating 3 HG3-del(11q) BIRC3MUT clones. In addition, single BIRC3MUT were introduced in HG3 and MEC1 CLL-derived cells for experimental validation (n = 3 clones/cell line). We first questioned whether monoallelic and biallelic BIRC3 loss had an impact in the DNA-binding activity of NF-κB transcription factors. Interestingly, HG3-del(11q) had higher p52 and RelB (non-canonical NF-κB signaling) activity than HG3WT cells (P = 0.005; P = 0.007), being this activity further increased in HG3-del(11q) BIRC3MUT cells (P & lt; 0.001; P & lt; 0.001). In depth analysis of the non-canonical signaling components by immunoblot revealed that HG3-del(11q) and, to a greater extent, HG3-del(11q) BIRC3MUT cells presented NF-κB-inducing kinase (NIK) cytoplasmic stabilization, high p-IKKα levels and p52-RelB nuclear translocation. Besides, HG3-del(11q) BIRC3MUT cells showed increased levels of the anti-apoptotic proteins BCL2 and BCL-xL. We next assessed this pathway ex vivo in stroma and CpG-stimulated primary CLL cells with or without BIRC3 deletion (n = 22; 11 each group). Remarkably, stimulated BIRC3-deleted primary cells showed higher p52 and RelB activity than BIRC3WT cases (P = 0.01; P = 0.07), and the percentage of BIRC3-deleted cells correlated with p52 activity in del(11q) cases (P = 0.04). We further performed western blot analyses in a homogenous cohort of del(11q) cases including (n = 4) or not including (n = 3) BIRC3 within the deleted region. Interestingly, del(11q)/BIRC3 deleted cases presented high levels of stabilized NIK, which correlated with higher p52 processing (P = 0.003). These patients also showed higher BCL2 levels than those del(11q)/BIRC3 undeleted, and we could further observe a correlation between p52 and BCL2 levels (P = 0.01). Given this p52-dependent BCL2 upregulation, we treated the CRISPR/Cas9 edited clones with venetoclax, demonstrating that HG3-del(11q) BIRC3MUT cells were more sensitive upon BCL2 inhibition than HG3WT clones (mean IC50 3.5 vs. 5.75 μM; P = 0.005). In vitro proliferation assays were performed to interrogate the impact of BIRC3 loss in CLL cell growth, revealing that HG3 BIRC3MUT cell lines had higher growth rates than BIRC3WT cells (P = 0.001). HG3-del(11q) BIRC3MUT cells also showed enhanced proliferation in comparison to HG3-del(11q) clones (P = 0.009). We further determined the clonal dynamics of del(11q) and/or BIRC3MUT cell lines in clonal competition experiments, showing that HG3 BIRC3MUT and HG3-del(11q) BIRC3MUT cells progressively outgrew HG3WT and HG3-del(11q) cells, respectively, overtime (P = 0.02; P = 0.006). Furthermore, we injected these edited cell lines into NSG mice (n = 20) in vivo, showing that mice xenografted with HG3 BIRC3MUT and HG3-del(11q) BIRC3MUT cells presented, by flow cytometry, an increase of human CD45+ cells in spleen 14 days after injection, compared to HG3WT and HG3-del(11q) cells (P = 0.02; P = 0.015). In summary, this work demonstrates that biallelic BIRC3 deletion through del(11q) and mutation triggers non-canonical NF-κB signaling, driving BCL2 overexpression and conferring clonal advantage, which could account for the negative predictive impact of BIRC3 biallelic inactivation in CLL. Taken together, our results suggest that del(11q) CLL patients harboring BIRC3 mutations should be considered as a CLL subgroup at a high risk of progression that might benefit from venetoclax-based therapies. Funding: PI18/01500 Disclosures No relevant conflicts of interest to declare.

Abstract: Most multiple myeloma (MM) patients will experience relapse due to the persistence of residual tumor cells, or MRD. We compared the prognostic value of traditional response criteria with MRD measured by three different methods: a sequencing-based method, termed the LymphoSIGHT™ platform, multiparameter flow cytometry (MFC) and ASO-PCR of Ig genes in a cohort of 133 uniformly-treated MM patients from the Spanish Myeloma Group trials. Methods Bone marrow samples were obtained from 133 patients at diagnostic and post-treatment time points on GEM clinical trials (GEM00 and GEM05). All 133 patients were either in CR or VGPR at the post-treatment time point. Using the sequencing assay, we identified clonal rearrangements of immunoglobulin (IGH-VDJ, IGH-DJ, and IGK) genes in diagnostic samples. We then assessed MRD in follow-up samples, analyzing concordance between: sequencing, MFC and ASO-PCR of Ig genes MRD results, and comparing the prognostic value of each method with traditional response criteria. Results The sequencing assay detected the presence of a myeloma-specific gene rearrangement in diagnostic samples from 121 of 133 (91%) patients. We tested MRD in follow-up time points in 109 of the 121 patients. Of the 109 patients, 79 were positive by sequencing at MRD levels of 10-5 or higher and 30 were MRD negative. The Time to Tumor Progression (TTP) and Overall Survival (OS) were significantly longer in the MRD negative group compared with the MRD positive group by sequencing (TTP, median 80 vs. 31 months, p 〈 0.0001; and OS, median not reached vs. 80 months p=0.02) (Figures 1A and 1B). All patients in VGPR, with the exception of 4 cases, were MRD positive by sequencing (92%). Three of the 4 cases with MRD negative and positive immunofixation became immunofixation negative after maintenance treatment. When restricting the analysis to the 61 patients that were in conventional CR (negative immunofixation), 35 of 60 patients were positive by sequencing at MRD levels at 10-5 and higher and 26 were MRD negative. There was a significantly improved TTP in the MRD negative group compared with the MRD positive group (median 131 vs. 35 months, p=0.001) (Figure 1C). A high correlation between MFC and sequencing MRD results was observed (r2=0.87); as well as between ASO-PCR of Ig genes and sequencing (r2=0.89). Discordant results between FCM and sequencing (SEQ) included: 14 cases who were positive by SEQ and negative by FCM, and 5 cases negative by SEQ but positive by FCM; while the remaining cases were concordant: 63 cases were positive by both methods and 16 were negative by both methods. Correlation between ASO-PCR and SEQ was possible in 45 patients: 10 were discordant (9PCR-SEQ+ and 1 PCR+SEQ-) while 35 were concordant (20 PCR+SEQ+, 15 PCR-SEQ-). Conclusions The sequencing applicability for MRD studies in MM is 91%, which is essentially equivalent with that of MFC (96% Rawstron AC et al, JCO 2013). There is a high correlation between MRD levels by sequencing, ASO-PCR and MFC. Based on these results, MRD assessment by sequencing is a useful method for patient risk stratification and can be used to determine molecular CR in MM. Disclosures: Pepin: Sequenta, Inc.: Employment, Equity Ownership. Weng:Sequenta, Inc.: Employment, Equity Ownership. Faham:Sequenta, Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees.

Abstract: Introduction Multiple Myeloma (MM) is a heterogeneous disease with a complex clonal and subclonal architecture with few recurrent mutations. The arrival of next-generation sequencing (NGS) has allowed us to have a deeper understanding of the disease. Due to that complexity and the low recurrence of "driver" mutations, the study of general mutational profile, copy number variation (CNV) and translocations is crucial to make an accurate diagnosis and prognosis. For that reason, a clinically validated NGS capture panel has been designed to analyze in a single assay all interesting genetic aberrations simultaneously including SNVs, indels, CNVs and chromosomal translocations. Methods In addition to genomic DNA (gDNA) from 33 healthy donors to create a robust baseline forCNV detection,we studied 161 DNA samples from 149 newly diagnosed MM patients enrolled in the GEM2012MENOS65clinical trial and treated homogeneously: gDNA from 149 BM CD138+ plasma cells and 12 paired cfDNA from peripheral blood samples obtained at diagnosis. First, starting with 100 ng of gDNA and 200ng for cfDNA samples, a custom targeted NGS panel using SureSelect capture technology (Agilent) followed by NextSeq500 (Illumina) sequencing identified SNVs, indels, CNVs and the most relevant IGH translocations within 26genes involved with MM. The average sequencing depth was 609x across samples; and 98% of the targeted regions were sequenced with & gt;200x. Second, NGS custom panel results were compared with FISH (n=88) and whole exome sequencing (SureSelect XT V6) (n=48) results. Both NGS panel and exome raw data were analyzed by DREAMgenics applying a custom bioinformatic pipeline. Finally, 5 discordant cases were followed-up by SNP-arrays. Results We have identified 408 exonic and non-synonymous variants. At least 1 oncogenic mutation was detected in 86% (128/149) of patients. NRAS was mutated in25% of patients, followed by KRAS(23%), BRAF(12%) DIS3(11%) and TP53(9%). Other interesting pathogenic mutations were identified in FGFR3 andHIST1H1E genes in 9% and 5% of patients, respectively. In 92% (11/12) of cfDNA samples at least 1 oncogenic mutation was detected. For this 12 cases, paired samples (BM CD138+vscfDNA) were available. A total of 39 somatic mutations were identified in those cases. In cfDNA, 10 mutations were detected, and 5 were present in both samples. Furthermore, a mean decrease of 0.19VAF was observed in cfDNA (0.12; 0.01-0.48) vs plasma cells (0.31; 0.01-0.51). Regarding to CNV, 1q gain was detected in 32% of patients (28/88), and 1p and 17p deletions in 17% (15/88) and 13% (11/88), respectively. Additionally, ATR and CRBN gene amplifications were detected in 22% and 16%, respectively. When these data were compared to FISH, a 75% of sensitivity and 91% of specificity was achieved by our method, with a PPV of 68% and a NPG of 93%. Translocations were identified in 28% (25/88) of patients, including 7% (6/88)) t(11;14), 14% (12/88), t(4;14), and 1 patient t(14;16). We also detected t(6;14)(p21;q32) IGH/CCND3 in 3 patients that had also been described in MM.Translocations were detected with a 94% of sensitivity, 99% of specificity, with a predictive positive value of 94% and a predictive negative value of 99%. Importantly, NGS-based method revealed a t(10;14) in 3 patients that had not been identified by FISH, a new translocation implying the miRNA hsa-mir-4537. Finally, the impact on PFS from FISH and NGS results was analyzed separately. PFS was similar for translocations and 17p deletions. However, 1p-detected by NGS showed a higher negative prognostic impact (p=0,006 vs p=0,127 by FISH)(Fig.1). Furthermore, our panel showed that 7% of patients (6/88) had a bi-allelic TP53 inactivation. Survival analysis showed that these patients relapsed significantly earlier than the others (p=0.028). Amplifications (≥4 copies) in 1q+could not identified with this panel. Conclusions Our custom NGS-based test allows in a single assay a more comprehensive study of the genomic landscape of MM patients by (a) detecting with a high sensitivity the most important and recurrent mutations and cytogenetic alterations, (b) identifying translocations and CNVs not previously detected by FISH and (c) identifying a double-hit MM patient. Additionally, cfDNA could be analyzed with this NGS strategy identifying molecular alterations in most of the patients. Disclosures Oriol: Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy. Sureda Balari:Takeda: Consultancy, Honoraria, Speakers Bureau; Celgene/Bristol-Myers Squibb: Consultancy, Honoraria; Roche: Honoraria; Sanofi: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Gilead/Kite: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Incyte: Consultancy; Celgene: Consultancy, Honoraria; BMS: Speakers Bureau; Merck Sharpe and Dohme: Consultancy, Honoraria, Speakers Bureau. de la Rubia:Janssen: Consultancy, Other: Expert Testimony; Celgene: Consultancy, Other: Expert Testimony; Amgen: Consultancy, Other: Expert Testimony; Ablynx/Sanofi: Consultancy, Other: Expert Testimony. Mateos:Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; PharmaMar-Zeltia: Consultancy; Abbvie/Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Honoraria; Regeneron: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Blade Creixenti:Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, BMS, Celgene, Janssen, MSD, Novartis, Takeda, Sanofi, Roche, Abbvie, GlaxoSmithKline and Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees. Garcia-Sanz:Novartis: Honoraria; Janssen: Honoraria, Research Funding; Incyte: Research Funding; Gilead: Honoraria, Research Funding; BMS: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria; Takeda: Consultancy, Research Funding. Martinez-Lopez:Novartis: Research Funding; BMS: Research Funding, Speakers Bureau; Incyte: Research Funding, Speakers Bureau; Janssen: Speakers Bureau; Roche: Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Vivia Biotech: Honoraria; Altum: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Hosea: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.