Clonal IgH Rearrangement Research Articles

CD3-positive plasmablastic B-cell neoplasms: a diagnostic pitfall

AbstractRare B-cell neoplasms with plasmablastic differentiation may aberrantly express CD3 by immunohistochemical staining, which places a great challenge for diagnosis. We here studied 17 cases of CD3+ plasmablastic B-cell neoplasms, including 12 plasmablastic lymphomas and 5 plasmablastic plasma cell myelomas. All 17 cases occurred in the extranodal sites with a male predominance (13/17). Four cases were initially misinterpreted by outside institutions, among which three were diagnosed as ‘peripheral T-cell lymphoma, not otherwise specified' and one was classified as ‘poorly differentiated neuroendocrine carcinoma'. The plasmablastic cells were present in all 17 cases diffusely or in a subset of tumor cells. CD3 expression was mostly diffuse (12/17) and moderate to strong (11/16) with a cytoplasmic staining pattern (14/16). Other T-cell markers were nearly absent, including CD2 (0/10), CD4 (1/13), CD5 (0/14), CD7 (0/11), and CD8 (0/13). CD138 was positive in all 17 cases and CD79a was variably positive in 8 of 14 cases. Only one case had immunoreactivity to CD20 (1/17) and PAX5 (1/12). CD56 expression and EBV infection were detected in 8/15 and 6/17, respectively. No HHV8 infection was noted in all 11 cases tested. Most cases (11/13) revealed either kappa or lambda light chain restriction. Of the nine cases studied, six had clonal IGH rearrangements but no clonal TRG rearrangements. Our study further emphasizes that the accurate classification of CD3+ plasmablastic neoplasms requires thorough morphologic examination, incorporation of more B-cell and T-cell markers in addition to CD3 and CD20, frequent addition of CD138 staining, and utilization of necessary molecular and genetic studies.

Abstract 2716: A multi-parameter assay for the detection of rare malignant cells in classical Hodgkin lymphoma

Abstract Background: Classical Hodgkin Lymphoma (CHL) ranks among the most frequently occurring lymphomas and is marked by Hodgkin and Reed-Sternberg (HRS) cells, frequently multi-nucleated neoplastic cells that are derived from germinal center B cells. The genetic alterations involved in the pathogenesis of this lymphoma have been difficult to study because HRS cells are rare and are surrounded by robust, non-neoplastic infiltrate, therefore they frequently represent less than 0.1% of cells within involved lymph nodes. Consequently, methods that isolate these rare cells are required to understand pathobiology of this lymphoma. We used the AccuCyte® - CyteFinder® system (RareCyte) to develop a method for detection and isolation of HRS cells. Methods: A 6-parameter immunofluorescence assay was designed to identify HRS cells that included HRS markers (CD40, CD30, CD15), CD3, combined CD20/CD14 and a cell membrane permeability viability dye. The assay was tested using the KMH2 Hodgkin lymphoma cell line spiked into PBMC and transferred to well slides for imaging by CyteFinder. This instrument utilizes 6-color scanning microscopy coupled with predefined algorithms to identify rare cell populations. The assay was then applied to a frozen fine needle aspirate (FNA) sample taken from the lymph node of a patient with histologically confirmed CHL. The FNA sample was thawed, prepared into a suspension, stained and analyzed as above. Cells identified with HRS phenotype were individually retrieved using the integrated CytePicker module. PCR of framework regions of the immunoglobulin heavy chain gene (IGH) was performed on single HRS cells (InvivoScribe) to assess clonality. Results: Of ~200 KMH2 cells spiked into blood, the assay identified 180 cells (90%) with the correct HRS phenotype. HRS phenotype cells were identified in the patient lymph node FNA sample. Two individual cells analyzed by IGH framework region PCR demonstrated identical size PCR products, indicating clonality of the B cell receptor rearrangement. Conclusion: A multi-parameter assay was successfully developed for identifying rare HRS cells with the CyteFinder system. Cells with HRS phenotype in a lymph node FNA sample were demonstrated to have clonal IGH rearrangements, demonstrating that actual HRS cells were identified. This method may be a useful tool for the diagnosis of CHL by identification of rare HRS cells from FNA specimens, as well as to investigate the molecular genomics of CHL. Citation Format: Lance U'Ren, David Wu, Jonathan R. Fromm, Jackie Stilwell, Eric Kaldjian. A multi-parameter assay for the detection of rare malignant cells in classical Hodgkin lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2716. doi:10.1158/1538-7445.AM2017-2716

Molecular Monitoring after Autologous Stem Cell Transplantation and Preemptive Rituximab Treatment of Molecular Relapse; Results from the Nordic Mantle Cell Lymphoma Studies (MCL2 and MCL3) with Median Follow-Up of 8.5 Years

The main objectives of the present study were to monitor minimal residual disease (MRD) in the bone marrow of patients with mantle cell lymphoma (MCL) to predict clinical relapse and guide preemptive treatment with rituximab. Among the patients enrolled in 2 prospective trials by the Nordic Lymphoma Group, 183 who had completed autologous stem cell transplantation (ASCT) and in whom an MRD marker had been obtained were included in our analysis. Fresh samples of bone marrow were analyzed for MRD by a combined standard nested and quantitative real-time PCR assay for Bcl-1/immunoglobulin heavy chain gene (IgH) and clonal IgH rearrangements. Significantly shorter progression-free survival (PFS) and overall survival (OS) was demonstrated for patients who were MRD positive pre-ASCT (54 patients) or in the first analysis post-ASCT (23 patients). The median PFS was only 20 months in those who were MRD-positive in the first sample post-ASCT, compared with 142 months in the MRD-negative group (P < .0001). OS was 75% at 10 years and median not reached in the MRD-negative group, compared with only 35 months in the MRD-positive group (P < .0001). Of the 86 patients (47%) who remained in continuous molecular remission, 73% were still in clinical remission after 10 years. For all patients, the median time from ASCT to first molecular relapse was 55 months, with a continuous occurrence of late molecular relapses. Fifty-eight patients who experienced MRD relapse received rituximab as preemptive treatment on 1 or more occasions, and in this group, the median time from first molecular relapse to clinical relapse was 55 months. In most cases, rituximab converted patients to MRD negativity (87%), but many patients became MRD-positive again later during follow-up (69%). By multivariate analysis, high-risk Mantle Cell Lymphoma International Prognostic Index score and positive MRD status pre-ASCT predicted early molecular relapse. In conclusion, preemptive rituximab treatment converts patients to MRD negativity and likely postpones clinical relapse. Molecular monitoring offers an opportunity to select some patients for therapeutic intervention and to avoid unnecessary treatment in others. MRD-positive patients in the first analysis post-ASCT have a dismal prognosis and thus are in need of novel strategies.

Combined IKZF1 and IG markers as new tools for diagnosis and minimal residual disease assessment in Tunisian B-ALL

The monitoring of minimal residual disease (MRD) approach in patients diagnosed with B-acute lymphoblastic leukemia (B-ALL) allows an early detection of residual clones inducing relapses and therefore appropriate therapy strategy. The molecular markers may identify and quantify the residual blasts in B-ALL with normal cytology. In this study, we aimed to use combined IKZF1, IGH and IGK immunoglobulin genes for diagnosis and MRD monitoring in B-ALL sample using MLPA, multiplex PCR and real-time quantitative PCR. We showed that multiplex PCR and MLPA are necessary and complementary to detect IKZF1 deletions. We have identified at the diagnosis clonal IGH rearrangement (VH3-JH5) and IKZF1 deletion (Δ4-7), which we have used it for MRD evaluation after induction chemotherapy. Despite the absence of chromosome abnormality, the patient may be classified in high-risk group with a relapse rate of residual blasts>10-4 and sensitivity up to 10-5. This molecular approach enabled the patient's stratification, which was overlooked by classical methods. The combined IKZF1 and immunoglobulin genes will be used as appropriate molecular tools for diagnosis and MRD assessment of B-lineage leukemias and introduced as a routine tests in Tunisian clinical laboratories. They will be useful to stratify patients into risk groups leading to better treatment strategy.

Primary Endometrial Marginal Zone Lymphoma (MALT Lymphoma): A Unique Clinicopathologic Entity.

Primary lymphoma of the endometrium is exceptionally rare. Several cases of distinctly nodular lymphoid proliferations confined to the endometrium have previously been described and reported as lymphomas of mucosa-associated lymphoid tissue (MALT). We report the largest series (n=8) of these lymphomas, further defining their morphologic, immunohistochemical, and molecular spectrum. Patients ranged in age from 50 to 87 (median, 62) years. None had a prior history of lymphoma, and lesions were incidental in all but 1 in which a polyp was noted on macroscopic examination. Nodules ranged from small, round, and uniform with minimal architectural effacement to large, expansile, and coalescing with foci of diffuse growth. In the majority, the nodules were confined to the endometrium; however, 2 cases showed myometrial involvement, 1 of which also had extensive extrauterine disease. The nodules comprised monomorphic populations of mature CD20 B lymphocytes with pale scant cytoplasm, CD43, BCL2, and IgM coexpression, and absence of CD10, CD23, and IgD expression. The nodules were associated with CD21/CD23 follicular dendritic meshworks. Clonality was detected in 6 lesions, in 4 by polymerase chain reaction for clonal IGH rearrangement and in 3 by in situ hybridization for immunoglobulin light chains. All were negative for IGH and MALT1 rearrangements by fluorescence in situ hybridization. None of the patients received additional therapy after resection, and most (7/8) are alive with no evidence of disease at last follow-up (mean 4.2 y), whereas the remaining patient is alive with stable disease. These findings demonstrate the unique clinical and pathologic features that characterize primary MALT lymphoma of the endometrium.

Lymphoma Heterogeneity: Three Different Histological Pictures and One Unique Clone.

We report a patient who developed up to three different lymphomas with the same clonal IGH rearrangement. She was first diagnosed of splenic zone marginal lymphoma and relapsed for the first time with Hodgkin lymphoma histology and later with diffuse large B-cell lymphoma histology. Subsequent biopsies and analysis of clonally rearranged IGH genes helped to elucidate the clonal relationship between the three histologies and to confirm a common origin from the three tissue histologies. An integrated diagnosis should always be performed in order to achieve the most accurate diagnosis and be able to choose the best therapeutic options for our patients.

Addition of Rituximab to Involved-Field Radiation Therapy Prolongs Progression-free Survival in Stage I-II Follicular Lymphoma: Results of a Multicenter Study

Rituximab (Rit) therapy added to involved-field radiation therapy (RT) has been proposed as an effective treatment for stage I-II follicular lymphoma (FL). The results of an observational multicenter study on the Rit-RT combination in limited-stage FL are here reported. Data have been collected from 2 consecutive cohorts of 94 patients with stage I-II FL treated between 1985 and 2011 at 5 Italian institutions. All patients had grade 1-3a FL, a median age of 54years (range: 25-82). The first 51 patients received RT alone (control group), while the subsequent series of 43 patients received 4 rituximab courses (375mg/m(2), days 1, 8, 15, 22) before RT (Rit-RT). Molecular disease was evaluated by nested bcl-2/IgH PCR or clonal IgH rearrangement was available in 33 Rit-RT patients. At a median follow-up of 10.9years (range: 1.8-22.9), the 10-year progression-free survival (PFS) and overall survival (OS) projections for the whole cohort were 57% and 87.5%, respectively. The 10-year PFS was significantly longer (P<.05) in the Rit-RT group (64.6%) compared to RT alone (50.7%), whereas the 10-year OS projections were not significantly different. On bivariate analysis controlling for stage, there was only a trend toward improved PFS for Rit-RT (HR, 0.55; P=.081). Follicular lymphoma international prognostic index and age were associated with OS but not with PFS on Cox regression analysis. Bone marrow molecular analysis showing PCR positivity at diagnosis was strongly associated with relapse risk upon univariate and multivariate analysis. This multicenter observational study suggests a potential benefit of adding rituximab to radiation therapy for stage I-II FL. The results of the currently ongoing randomized studies are required to confirm these results. The study underlines the importance of molecular disease monitoring also for patient with limited-stage disease.

Prognostic Impact, Phenotypic and Molecular Characterization of Concordant and Discordant Bone Marrow Involvement in Patients with Diffuse Large b-Cell Lymphoma

INTRODUCTIONIn the rituximab era, the prognostic influence of bone marrow (BM) infiltration in patients with diffuse large B-cell lymphoma (DLBCL) has been hardly studied. In this retrospective observational study, we aim to investigate the prognostic influence of concordant and discordant BM infiltration in patients with histological diagnosis of DLBCL. In addition, we analyzed the possible clonal relationship between BM and lymph node tumor cells in the cases with discordant histology. PATIENTS AND METHODSAll patients diagnosed of DLBCL in our center from January 1, 1999 were included in the study. Histological BM infiltration pattern was classified as concordant (DLBCL infiltration) or discordant (small or low-grade B-cell lymphoma) based on the diagnostic reports from the Pathology department. All cases were reviewed for this purpose by an expert pathologist. To further characterize the discordant cases, flow cytometry (FCM) reports of BM infiltration were reviewed. In the discordant cases, the clonal IGH rearrangement was studied in both BM and lymphadenopathy, by amplification of the VDJ genes as recommended in the BIOMED-2 protocol. For survival analysis, only patients treated with R-CHOP or similar were included. RESULTS236 patients diagnosed of DLBCL were included in the study; of them, 31 (13%) had concordant histological BM infiltration and 18 (7.6%) discordant. Phenotypic characterization by FCM of the discordant cases was heterogeneous: chronic lymphocytic leukemia (N = 2), follicular lymphoma (N = 5), marginal zone lymphoma (N = 2), non-specific phenotype (N = 5) or non-infiltration (N = 2). Clonality studies were performed in the discordant cases. Good quality DNA was obtained in 17 out of 18 patients. We confirmed the same clone in both BM and lymphadenopathy in 12 patients (70%); different clones were observed in two, and a polyclonal pattern was obtained in the remaining three patients. Survival analyzes were conducted only in the 186 patients treated with R-CHOP or similar. With a median follow up of 58 (1-135) months, PFS was significantly worse in patients with concordant (35% at 5 years, p = 0.001) or discordant (35% at 5 years, p = 0.04) histology, compared to patients without infiltration (64% at 5 years) (Figure 1). OS was significantly lower in patients with concordant histology (53% at 5 years, p = 0.05), whereas there was no significant difference between patients with discordant infiltration (62% at 5 years, p = 0.8) and non-affected BM (75% at 5 years). In the multivariate analysis, concordant BM infiltration (HR = 2.25, 95% CI 1.2 to 4.3, p = 0.01) had a negative influence on PFS (but not on OS), independently of the age, ECOG and LDH, while discordant histology was close to statistical significance (RR = 2; 95% CI 0.95 to 3, p = 0.1) CONCLUSIONSOur results indicate that BM infiltration, both concordant and discordant, is associated with a lower PFS in DLBCL patients treated with R-CHOP or similar. Cases with discordant BM infiltration have a very heterogeneous phenotype, but we found a clonal relationship between the two different histologies in a high proportion of cases, indicating a probable histologic transformation from a low-grade lymphoma. Further studies are needed to determine the sequence of biological events that might be involved in this transformation. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Diffuse Large B-Cell Lymphoma Patient-Derived Xenograft Models Capture Molecular and Biologic Heterogeneity and Inform Therapy

Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease defined by different transcriptional classifications, associated signaling and survival pathways and additional recurrent genetic alterations. In the cell-of-origin (COO) scheme, DLBCLs subtypes share certain features with normal germinal center B-cells (GCB) and activated B-cells (ABC). In comparison to GCB DLBCLs, ABC tumors have increased baseline NFκB activity and more frequent genetic alterations of NFκB pathway components. DLBCLs with shared functional features are also defined by the consensus clustering classification (CCC) which delineates B-cell receptor (BCR), Oxidative Phosphorylation (OxPhos) and Host Response (HR) tumors. BCR DLBCLs have increased reliance on BCR-signaling and survival pathways and aerobic glycolysis. BCR-dependent DLBCLs with high or low baseline NFκB activity (which largely correspond to ABC or GCB tumors, respectively) have distinct SYK-PI3K-dependent survival pathways and shared sensitivity to proximal BCR pathway inhibitors. Although DLBCLs have infrequent inactivating somatic mutations of TP53, these tumors commonly have copy number alterations (CNAs) of TP53 and genes encoding cell cycle pathway components.Given the clinical and molecular heterogeneity of DLBCL, we sought to develop faithful subtype-specific model systems to assess targeted therapies. Fresh tumor biopsies from 27 primary LBCLs were implanted under the renal capsule of immune compromised NSG mice. Nine of 27 tumors were successfully expanded in vivo, serially propagated for > 5 generations and considered stable LBCL PDX models. All models were EBV- and had clonal IgH rearrangements. Morphological and immunohistochemical signatures defined 8 PDX models as DLBCL and 1 as EBV- plasmablastic lymphoma (PBL).All LBCL PDX models were subjected to RNA-Seq and classified with respect to COO and CCC subtypes. Models were also evaluated by whole exome sequencing with a modified bait set which captured coding mutations and selected chromosomal rearrangements. Six of 9 DLBCL PDX models were ABC type. These models exhibited mutations of MYD88 alone or in association with PIM1 or CD79B with other alterations, as reported in primary ABC DLBCLs. The remaining 2 DLBCL PDX models were GCB type, with characteristic alterations of GNA13 and EZH2, and chromosomal translocations involving IgH and either BCL2 or MYC. Of note, BCL2 and MYC translocations are known adverse prognostic features of primary GCB DLBCL. Certain PDX models had additional mutations including B2M, MLL2, TNFAIP3, MEF2B and TP53.Only 25% (2/8) of the DLBCL PDX models harbored inactivating TP53 mutations whereas 75% (6/8) of tumors exhibited CNAs of TP53 or its upstream modifier, CDKN2A. These data are consistent with the reported incidence and type of TP53 pathway alterations in primary DLBCLs and contrast sharply with the near-uniform presence of TP53 mutations in DLBCL cell lines.Using the CCC classification, 6/8 DLBCL PDX models (both GCBs and 4 of 6 ABCs) were defined as BCR-subtype and 2 models as non-BCR type. To assess the utility of the DLBCL PDX models for functional analysis of BCR signaling, we first assessed cell surface immunoglobulin (sIg) expression by flow cytometry. All 6 BCR-type DLBCLs expressed sIgM whereas the 2 non-BCR DLBCL models and the PBL model lacked sIg. Next, we treated viable tumor cell suspensions with a selective SYK inhibitor, entospletinib (GS-9973). SYK inhibition significantly decreased the proliferation of all 6 BCR-type DLBCLs, but had no effect on the non-BCR-type DLBCLs or the PBL PDX. Given the distinctive SYK/PI3K-dependent signaling and survival pathways in DLBCLs with low or high baseline NFκB, we also assessed selective apoptotic pathway readouts in entospletinib-treated PDX cell suspensions. SYK inhibition selectively upregulated the pro-apoptotic BH3 family member, HRK, in BCR-dependent GCB-type DLBCL PDX samples and significantly downregulated the anti-apoptotic BCL2 family member, BCL2A1, in BCR- dependent ABC-type DLBCL PDX tumors, effects consistent with those previously observed in primary DLBCL samples.In summary, we have established and molecularly characterized faithful PDX models of DLBCL and PBL and demonstrated their usefulness in evaluating novel BCR pathway inhibitors. DisclosuresRodig:Perkin Elmer: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding. Shipp:Gilead: Consultancy; Sanofi: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Single Cell Analysis of IG Genes in CLL: Cases with Multiple IGH Rearrangements Are Constituted of Several Independent Clones Even When Indistinguishable By Flow Cytometry

Abstract Current evidence suggests that in 2-5% of chronic lymphocytic leukemia (CLL) cases, multiple B cell clones - each expressing unique productive immunoglobulin gene rearrangements (P-IGH)- can be detected. However, only in 35% of them, coexistence of at least two leukemic clones was revealed by flow-cytometry (Plevova et al, Haematologica 2014). In the remaining 65% of cases, presence of multiple clones was presumed based on the number of immunoglobulin gene rearrangements detected, but underlying biological cause, also possibly including lack of allelic exclusion, was not satisfactorily proven at the level of single cells. Therefore, we developed a technique for simultaneous analysis of IGH, IGK and IGL rearrangements at the single cell level and performed further investigation of cases with multiple P-IGH. In years 2006-2015, patients with multiple clonal P-IGHs were searched among 1670 CLL patients examined for IGHV mutation status. Identified cases were submitted to flow-cytometric measurement of surface markers CD5, CD19, CD20, CD23, CD43, CD45, sIgK, sIgL and FMC7 on sorted cells where possible. Based on this examination, patients with clonal P-IGHs exceeding the number of CLL populations distinguished by flow-cytometry were tested using single cell analysis. Patients with corresponding number of P-IGHs and CLL populations (i.e. confirmed as biclonal CLL according to the flow-cytometry and PCR-based IGH detection) served as a control of the technique accuracy. Single cell analysis technique was developed at our department to detect transcribed IGH, IGK and IGL simultaneously in individual cells. B cells from peripheral blood of CLL patients were separated by gradient centrifugation with depletion of non-B cells. Single CD19+ cells were then sorted using FACS Aria III into 96-well plates containing lysis buffer, followed by 2 rounds of multiplex nested RT-PCR, capillary electrophoresis and Sanger sequencing. For each patient, 1-3 plates were analyzed. To consider an IG rearrangement clonal, it had to be detected at least in 3 wells. We detected multiple clonal P-IGHs in 76/1670 (4,6%) CLL patients analyzed. Expression of surface markers was assessed by flow cytometry in 37/76 patients: In 24/37(65%), the number of P-IGHs exceeded number of distinguished populations. Single cell analysis was performed in 16/24 cases, 15/16 patients displayed only one homogeneous CLL population by flow cytometry and 1/16 patient displayed two distinguished populations but three P-IGHs. Two patients with corresponding number of P-IGHs and CLL populations were used as a control. The median of wells tested per patient was 92 and P-IGH detection efficacy 83%. In 12/16 tested patients, as well as in two controls, no cell with more than one P-IGH was detected, confirming the expansion of multiple B-cell clones in all of them. Also, based on the structure of detected clonal IGH rearrangements in each case, a possibility of VH replacement was excluded. In 2 cases, we observed intraclonal diversification within one of the present clones (expressing either IGHV1-69, or IGHV3-72), a rare phenomenon described in CLL. In the remaining 4/16 cases we failed to detect one of the expected P-IGHs likely due to its underrepresentation in a sample, which is supported by results obtained from quantitative PCR with allele-specific primers in a bulk sample. Light chains were successfully detected in 10/12 analyzed cases and two controls; in 4 cases, single cell analysis revealed transcribed clonal IG rearrangements previously undetected in bulk samples. Importantly, each identified clonal IGK/IGL was repeatedly detected exclusively with only one distinct clonal P-IGH, thus constituting independent B cell receptors in independent leukemic clones. We confirm and substantially extend the notion that oligoclonality is the major cause of multiple P-IGH detection in CLL. Obtained information on P-IGH and P-IGK/L pairing will help in further investigation of IG receptors in oligoclonal CLL, as the biological background of oligoclonality in CLL still remains to be elucidated. Supported by grants IGA NT13493-4/2012, MUNI/A/1180/2014 and AZV 15-30015A. Disclosures No relevant conflicts of interest to declare.

Application of BIOMED- 2 standardized Ig gene rearrangement system in multiple myeloma

目的探讨BIOMED-2标准化Ig基因重排技术在多发性骨髓瘤（MM）诊治中的应用以及采用PCR片段分析毛细管电泳法（简称毛细管电泳法）进行克隆性检测的意义。方法选取2009年至2013年167例MM患者骨髓标本，以20例反应性浆细胞增多症患者骨髓标本作为对照，采用BIOMED-2系统引物，进行多重PCR扩增并采用毛细管电泳法进行Ig基因重排的克隆性分析。结果①167例MM患者中IgH VH-JH重排阳性者107例，阴性者60例，两组患者中IgH DH-JH重排发生率差异有统计学意义（14.0％对30.0%，P=0.013）；121例（72.4%）患者存在IgK重排。IgH VH-JH、IgH DH-JH、IgK联合检查，阳性检出率为94.6%。对照组Ig基因重排检测结果均为阴性。②琼脂糖电泳法结果示167例MM患者中9例（5.4%）患者IgH重排基因克隆性阳性，而毛细管电泳法结果则示为多克隆重排。③53例MM患者同时进行Ig基因重排检测和染色体荧光原位杂交IgH检测，两种方法的IgH阳性检出率差异有统计学意义（67.9％对49.1%，P=0.049）。结论IgH VH-JH、IgH DH-JH、IgK联合检测可大大提高MM患者Ig基因重排克隆性的检出率，尤其对于IgH VH-JH重排阴性者IgH DH-JH重排的补充检测尤为重要。基因重排检测采用毛细管电泳法可有效地区分单克隆、多克隆和寡克隆。Ig基因重排检测较染色体荧光原位杂交技术的IgH阳性检出率高。应用BIOMED-2标准化Ig基因重排技术检测对于MM的诊断有指导意义。

Pretransplantation Minimal Residual Disease Predicts Survival in Patients with Mantle Cell Lymphoma Undergoing Autologous Stem Cell Transplantation in Complete Remission.

Autologous stem cell transplantation (ASCT) is standard therapy for mantle cell lymphoma (MCL) in remission after induction chemotherapy, with the best results for patients in complete remission (CR). We hypothesized that evaluation of minimal residual disease (MRD) before ASCT could further stratify outcomes for these patients. Patients with MCL who underwent ASCT in clinical CR between 1996 and 2011 with pretransplantation MRD testing were eligible. Presence of a clonal IgH rearrangement, t(11; 14) by PCR or positive flow cytometry from blood or bone marrow, was considered positive. An adjusted proportional hazards model for associations with progression-free (PFS) and overall survival (OS) was performed. Of 75 MCL patients in CR, 8 (11%) were MRD positive. MRD positivity was associated with shorter OS and PFS. The median OS for MRD-negative patients was not reached, with 82% survival at 5years, whereas for the MRD-positive patients, median OS was 3.01years (hazard ratio [HR], 4.04; P= .009), with a median follow-up of 5.1years. The median PFS for MRD-negative patients was not reached with 75% PFS at 5years, whereas for MRD-positive patients, it was 2.38years (HR, 3.69; P= .002). MRD positivity is independently associated with poor outcomes after ASCT for MCL patients in CR.

Establishment and characterization of a nude mice model of human diffuse large B-cell lymphoma

To establish a diffuse large B-cell lymphoma (DLBCL)-mice model using human DLBCL cell line LY8, to investigate its characteristics of growth and to provide a model for in vivo study of DLBCL pathogenesis and treatment. LY8 cells were injected subcutaneously into the right flank of nude mice. Harvested tumor tissues were cut into small pieces of 1.5 mm × 1.5 mm × 1.5 mm and implanted subcutaneously into nude mice. Tumor growth was visualized and the histologic characteristics were documented. Expression of LCA, CD20, CD79α, Ki-67, CD3, CD45RO, bcl-6, MUM-1, CD10 and bcl-2 were examined by using immunohistochemistry. IgH clonal rearrangement and status of three microsatellite loci (D14S68, D18S69, D20S199) in the xenografted tumor samples and the parental cell line LY8 were detected using PCR amplification followed by PAGE. The subcutaneous xenograft DLBCL model was successfully established by using cell line LY8, and a stable growth was achieved up to the 9th generation. The tumor in each generation showed similar growth characteristics and the rate of subcutaneous tumor formation was 91.9% (114/124). The tumor growth was observed from the 2nd week after implantation, reaching 1.3 cm in major diameter at the 3rd week and 2.0 cm at the 4th week. The tumor had identical morphological characteristics with those of human DLBCL, and expressed LCA, CD20, CD79α, bcl-6, MUM-1, CD10 and bcl-2. The tumor of xenograft mice and cell line LY8 showed identical IgH rearrangement and microsatellite length. A human DLBCL bearing mouse model was successfully established. The mice model is similar to human counterpart with high stability and repeatability. Therefore, it provides an ideal animal model for in vivo studies of the biological characteristics and treatment of DLBCL.

Diagnostic Tumor Mirna Profiling Predicts Molecular Relapse in Mantle Cell Lymphoma Patients Prospectively Followed for Minimal Residual Disease. Results from the Nordic MCL2-3 Trials

Background Mantle cell lymphoma (MCL) is a subtype of non-Hodgkin‘s lymphoma (NHL) with a variable but often aggressive clinical course. The majority of MCL patients ≤65 years will experience clinical relapse during a 10-year period (Geisler et al. Br J Haematol 2012). Risk-stratification is therefore of great importance in order to identify patients who are eligible for novel or alternative treatment regimens. Minimal residual disease (MRD) monitoring can predict clinical progression in MCL and guide pre-emptive treatment with rituximab as single agent. It has thus far not been possible to predict post-treatment molecular relapse (MRD-positivity). Although some recent studies have shown that aberrant miRNA expression delineate pathogenic molecular pathways and predict survival in MCL patients, miRNA profiling has not been performed in the context of MRD and molecular relapse.Aims We assessed MCL miRNA expression, in a large, prospective, uniformly treated patient cohort followed with molecular markers for MRD to determine if miRNAs could predict molecular relapse.Methods Diagnostic MCL tumor samples from 114 patients in the Nordic MCL2 and MCL3 clinical trials were retrieved. All patients had confirmed CyclinD1 overexpression and 96 patients had Ki-67 expression measurement for use in the MIPI-B predictive score. All patients received almost identical induction treatment with six alternating cycles of maxi-CHOP and high-dose Ara-C in combination with rituximab. Patients in remission were consolidated with high dose chemotherapy followed by autologous stem cell transplantation. All patients had a molecular marker (PCR detectable t(11;14) or clonal IgH rearrangement) for MRD. The median follow-up was 6.4 years for the MCL2 cohort and 3.7 years for the MCL3 cohort. 19 miRNAs, previously found to have prognostic significance in MCL (Husby et al EHA 2014), were measured by qRT-PCR and analyzed in concordance with MRD-data. The main endpoint was first event of molecular relapse (MRD-positive sample).Results Of the 114 patients in the study, 71 (62%) patients became MRD-positive in the follow-up period. Of the 19 examined miRNAs, 10 miRNAs showed unique qPCR melting curves and were analyzed with respect to MRD. Four miRNAs (miR-92a, miR-3687, miR-486-5p and miR-185-5p) were significantly up-regulated in patients who had molecular relapse (t-test; respectively p = 0.010, p = 0.019, p = 0.048, p = 0.043). However miR-18b, previously identified as prognostic marker regarding survival, was not significantly overexpressed. We hereafter investigated if a newly derived prognostic score, the MIPI-B-miR, which incorporates miR-18b with the MIPI-B, could predict molecular relapse. The MIPI-B-miR high-risk patients had significantly shorter time to first molecular relapse than MIPI-B high-risk patients (Figure 1). Functional studies of these aberrantly expressed miRs are ongoing.Conclusion Patients with molecular relapse had significantly increased levels of miR-92a, miR-3687, miR-486-5p and miR-185-5p, and MIPI-B-miR improved MRD prediction compared to MIPI-B. Aberrant miRNA profiles may be able to predict molecular relapse, and may already at diagnosis identify patients eligible to anti-CD20 antibody maintenance or alternative regimens. However validation in other cohorts is needed. [Display omitted] DisclosuresKolstad:Nordic Nanovector: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Räty:GlaxoSmithKline Ltd: Honoraria; Roche Ltd: Membership on an entity’s Board of Directors or advisory committees; Mundipharma: Honoraria.

Favorable Outcomes for Older Adolescents and Young Adults (AYA) with Acute Lymphoblastic Leukemia (ALL): Early Results of U.S. Intergroup Trial C10403

▪Background: Retrospective analyses have demonstrated significantly improved survival for AYA ALL patients (pts) aged 16-21 years (yrs) when treated on pediatric versus adult U.S. NCI Cooperative group regimens where 2-yr event-free survivals (EFS) have been only 35-40%. The purpose of C10403, a large prospective US intergroup trial, was to evaluate the feasibility and effectiveness [with EFS as a primary endpoint), of treating AYA ALL pts (ages 16-39 yrs) using the standard arm of the successful Children’s Oncology Group regimen (COG AALL0232) .Methods: Newly diagnosed AYA patients with B-precursor (B-ALL) or T-precursor (T-ALL) ALL were eligible to enroll on C10403. Burkitt type and Ph+ ALL were excluded. The regimen was identical to the Capizzi methotrexate arm of COG AALL0232 (Larsen E. JCO 2011; 29 suppl:3) and consisted of four intensive courses: remission induction, remission consolidation, interim maintenance, delayed intensification, and prolonged maintenance therapy. Pts with M2 marrow response (>5% but < 25% lymphoblasts) after remission induction received an extended remission induction course of therapy. Events were defined as induction failure (M3 [³25% blasts] day 29 of induction or M2 day 43 of extended induction), death, relapse, or second malignancy. Key correlative science studies in a subset of the total accrued population included assessment of Minimal Residual Disease (MRD) using quantitative real-time PCR of clonal IgH or TCR gene rearrangements as well as Low Density Microarray (LDA) assays designed to detect a previously validated gene expression profile (Harvey, R; ASH 2013, abstract 826) which can prospectively identify ALL pts with Ph-like (BCR-ABL1-like) ALL.Results: 318 pts were enrolled on C10403 from 11/2007 to 8/2012; 22 withdrew prior to therapy. Of 296 evaluable pts, the median age at diagnosis was 24 yrs (range: 17 to 39): 25% were 17-20 yrs, 53% were 21-29 yrs, and 22% were 30-39 yrs. The majority had B-ALL (76%) and were male ( 61%). Approximately 25% were non-Caucasian and 15% were Hispanic or Latino. 32% of pts were obese (BMI³30). There were 5 (2%) treatment-related deaths during protocol therapy: liver failure (n=2, both during induction), infection (1 in induction, 1 in consolidation), and ventricular arrhythmia (1 in induction). Overall, treatment toxicities were similar to those reported in the standard arm of COG AALL0232, with an increased thrombosis and early hyperbilirubinemia for C10403 pts, as reported previously (Advani A, ASH 2013, abstract 303). To date, 70 deaths have been reported and 87 pts remain on protocol therapy. With a median follow-up of 28 months for surviving pts, 105 events have been observed. The median EFS overall is 59.4 months (95% CI: 38.4 to NR) and the 2-yr EFS rate overall is 66% (95% CI: 60 – 72%) [Fig 1a] with similar 2-yr EFS rates for B and T- ALL pts (65%, and 68%). The 2-yr OS rate is 78% (95% CI: 72 – 83%)[Fig 1b], which is similar for B (78%, 95% CI: 72 – 84%) and T-ALL, (80%, 95% CI: 70 – 91%). These results allow rejection of the null hypothesis of this Phase II trial that the true median EFS is, at most, 32 months. In multivariable analysis of presenting clinical features, age > 20 years and initial WBC count ³ 30k/microliter were significantly associated with worse EFS and OS. Presence of MRD at day 28 following initiation of induction therapy and presence of a Ph-like gene expression signature were significantly associated with both worse EFS and OS. Notably, absence of detectable MRD noted in 22/58 [38%] evaluable pts at day 28 of induction was associated with 100% EFS (p=0.0006). The Ph-like like signature was detected in 28% of pts tested on C10403 and the 2 yr EFS for these patients was only 52%, compared to 81% for those without Ph-like disease (p = 0.04).Conclusions: This large prospective US adult intergroup trial (C10403) for pts 16-39 years old employing an intensive pediatric regimen demonstrates a significant improvement (compared to historical controls) in AYA EFS and OS and validates this approach for treatment of AYA with ALL by adult hematologists. The improved clinical outcomes and the predictive value of the correlative studies in this trial lay the foundation for the design of future trials, where incorporation of novel agents to eradicate MRD, and/or use of tyrosine kinase inhibitors to target the frequently detected Ph-like ALL in AYA pts may further improve survival for young adults with ALL. [Display omitted] [Display omitted] DisclosuresStock:Sigma-Tau: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Advani:Sigma Tau: Membership on an entity’s Board of Directors or advisory committees; Jazz: Membership on an entity’s Board of Directors or advisory committees. Liedtke:Onyx: Membership on an entity’s Board of Directors or advisory committees. Larson:Novartis: Consultancy, Research Funding.

Cell-Free DNA for Minimal Residual Disease Monitoring in Multiple Myeloma Patients

BackgroundCirculating nucleic acids, such as cell-free DNA (cf-DNA), are becoming a promising minimally-invasive diagnostic tool for cancer detection. Recent studies demonstrated that tumor-derived cf-DNA can be used to monitor tumor burden and response to treatment in patients (pts) with solid tumors as well as hematological malignancies (Dawson et al, 2013, Armand et al, 2013). In this study we investigated the clinical utility of cf-DNA in the monitoring of minimal residual disease (MRD) of pts with multiple myeloma (MM) carrying the tumor specific immunoglobulin (IGH) rearrangement.MethodsCf-DNA was extracted from 1 ml of serum sample from 13 MM patients enrolled in Italian CRD/MEL-200 and EMN-02 protocols. The total amount of cf-DNA was estimated by fluorometric measurement (median 560 ng, range 15-5158 ng) and the length of fragments was evaluated by high sensitivity dsDNA chips (Agilent). Patient specific clonal IGH rearrangement was identified at the time of diagnosis from bone marrow (BM) genomic DNA (gDNA) as previously reported (Ladetto et al, 2000). For each patient, MRD in BM and peripheral blood (PB) was estimated by real time quantitative PCR (qPCR) using ASO-specific primers and the quantification was based on serial 10-fold dilution standard curves from plasmid carrying the patient specific IGH rearrangement. The amount of IGH rearrangement in cf-DNA (cf-IGH) was estimated by qPCR and droplet digital PCR (ddPCR) (Bio-Rad) on diagnostic and follow up samples and was expressed as the amount of copies per 1 µg of total cf-DNA. qPCR and ddPCR results were interpreted according to the Euro-MRD guidelines (van der Velden et al, 2003).ResultsOverall, 54 cf-DNA samples from MM serum (13 diagnostic, 41 follow-up samples) were analyzed for the presence of patient specific IGH rearrangement. The most abundant fraction of cf-DNA was 180-220bp, than 350-400bp and 700-10000bp (in 100%, 85% and 68% of samples respectively), whereas longer fragments more often appeared in follow-up samples. By qPCR, cf-IGH at diagnosis were observed in 11/13 diagnostic samples. Only 3/13 pts were quantifiable (116, 85, 187 copies/1 µg of cfDNA) and 8/13 pts were positive but not quantifiable (PNQ) cf-IGH. By ddPCR, levels of cf-IGH at diagnosis were observed in 9/13 pts. 6/13 pts were quantifiable (246, 195, 96, 88, 184, 25 copies/1µg of cfDNA), and only 3/13 pts were PNQ. In follow-up samples, levels of cf-IGH were undetectable by qRT-PCR; however in 5 samples they were PNQ by ddPCR. Interestingly, in one available relapse sample, cf-IGH reappeared again to quantifiable level (61 copies by qRT-PCR and 190 copies by ddPCR). The levels of cf-IGH are quantifiable in samples with higher amount of tumor specific IGH rearrangements in BM or PB; however, no association was observed between cf-IGH level at diagnosis and disease burden estimated by the PCs infiltration in BM or the monoclonal immunoglobulin concentration in blood/urine.ConclusionsThese data show the potential utility of cf-IGH monitoring in MM pts. Although by qPCR, cf-IGH were detected in 11/13 pts, they were quantifiable only in 3/13 pts and ddPCR was more precise as it was able to quantify cf-IGH in 6/13 pts. Since cf-IGH copies were quantifiable only in diagnostic samples and in 1 available sample at the relapse, we conclude that higher amounts of serum are necessary to overcome the limitation of assay sensitivity. Potential advantages and predictive value, for monitoring tumor marker in a non-invasive manner, need to be further validated on larger cohort of samples using increased amount of cf-DNA. Work was supported by IGA grants NT12130, NT14575. This work is funded by a Black Swan Research Initiative grant by the International Myeloma Foundation "Dynamics of microRNA and cell-free DNA profiles during multiple myeloma progression“. DisclosuresBoccadoro:Celgene: Honoraria; Janssen: Honoraria; Onyx: Honoraria. Palumbo:Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Array BioPharma: Honoraria; Genmab A/S: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Onyx Pharmaceuticals: Consultancy, Honoraria; Sanofi Aventis: Honoraria.

Detection of minimal residual disease in B lymphoblastic leukemia by high-throughput sequencing of IGH.

High-throughput sequencing (HTS) of immunoglobulin heavy-chain genes (IGH) in unselected clinical samples for minimal residual disease (MRD) in B lymphoblastic leukemia (B-ALL) has not been tested. As current MRD-detecting methods such as flow cytometry or patient-specific qPCR are complex or difficult to standardize in the clinical laboratory, sequencing may enhance clinical prognostication. We sequenced IGH in paired pretreatment and day 29 post-treatment samples using residual material from consecutive, unselected samples from the Children's Oncology Group AALL0932 trial to measure MRD as compared with flow cytometry. We assessed the impact of ongoing recombination at IGH on MRD detection in post-treatment samples. Finally, we evaluated a subset of cases with discordant MRD results between flow cytometry and sequencing. We found clonal IGH rearrangements in 92 of 98 pretreatment patient samples. Furthermore, while ongoing recombination of IGH was evident, index clones typically prevailed in MRD-positive post-treatment samples, suggesting that clonal evolution at IGH does not contribute substantively to tumor fitness. MRD was detected by sequencing in all flow cytometry-positive cases with no false-negative results. In addition, in a subset of patients, MRD was detected by sequencing, but not by flow cytometry, including a fraction with MRD levels within the sensitivity of flow cytometry. We provide data that suggest that this discordance in some patients may be due to the phenotypic maturation of the transformed cell. Our results provide strong support for HTS of IGH to enhance clinical prognostication in B-ALL.

Robust Detection Of Minimal Residual Disease In Unselected Patients With B-Cell Precursor Acute Lymphoblastic Leukemia By High-Throughput Sequencing Of IGH

High-throughput sequencing (HTS) of immunoglobulin heavy chain genes (IGH) may be useful for detecting minimal residual disease (MRD) in acute lymphoblastic leukemia. We previously demonstrated the first application of high-throughput sequencing for the detection of minimal residual disease in T-cell precursor acute lymphoblastic leukemia (TPC-ALL) (Sci. Transl. Med. 4(134):134ra63. 2012). Recently, Faham and colleagues considered deep sequencing for MRD detection in B-cell precursor acute lymphoblastic leukemia (BPC-ALL) (Blood 120(26):5173-80, 2012). As this prior analysis in BPC-ALL apparently focused only on samples known to have a clonal rearrangement in IGH, the potential applicability and wide-spread utility of sequencing of IGH in unselected clinical samples for MRD has not been tested.Here, we consider an unselected cohort of patients enrolled in Children Oncology Group AALL0932 trial and use residual material from 99 patient samples submitted for routine multi-parametric flow cytometry (mpFC) at U. of Washington. One sample failed in the initial DNA extraction step and was not further considered. We show using high-throughput sequencing that clonal IGH rearrangements can be identified in 92 of the remaining 98 pre-treatment samples, using a definition of a V-D-J or D-J rearrangement comprising at least 10% of total nucleated cells (Fig. 1A). Similar to our prior findings in TPC-ALL, we find three subsets of patients—1) those for whom MRD is not detected by either flow cytometry or HTS; 2) those for whom MRD is detected both by flow cytometry and HTS; and 3) those for whom MRD is detected only by HTS, but not flow cytometry (Fig. 1B). There were no false negative results by HTS as compared to flow cytometry. [Display omitted] In the third group (HTS+positive, flow cytometry-negative), a subset of these patients, (5 of 28) had MRD detectable by HTS at a level within the expected sensitivity of flow cytometry. We hypothesized that in these cases that post-treatment MRD sequences may be present within the maturing B cell compartment that is not immunophenotypically aberrant by flow cytometry. To test this hypothesis, we analyzed eight additional post-treatment samples that were negative for MRD by flow cytometry. The mature B-cell fraction was collected by triple, flow cytometry-sorting and then sequenced by HTS for IGH rearrangements to search for the index clone defined in the corresponding, paired pre-treatment samples. Although a limited finding, diagnostic index IGH sequence was indeed identified in one of eight samples, in only the mature B-cell fraction, which is consistent with the proportion of cases with high-level MRD detected by HTS but which was missed by flow cytometry. Taken together, our results provide additional support for assessment of MRD in acute lymphoblastic leukemia by high-throughput sequencing. Our findings argue that precise quantification of the level of MRD by HTS will be important, and suggest that clonal IGH rearrangement sequences may be detected in an immunophenotypically normal population of mature B cells that may not be detected by flow cytometry. Disclosures:Emerson:Adaptive Biotechnologies: Employment, Equity Ownership. Sherwood:Adaptive Biotechnologies: Employment, Equity Ownership. Kirsch:Adaptive Biotechnologies: Employment, Equity Ownership. Carlson:Adaptive Biotechnologies: Consultancy, Equity Ownership, Patents & Royalties. Williamson:Adaptive Biotechnologies: Employment, Equity Ownership. Wood:Becton Dickinson and Company, NJ, USA: Research Funding. Robins:Adaptive Biotechnologies: Consultancy, Equity Ownership, Patents & Royalties.

A Comparative Analysis Of Next-Generation Sequencing and Real-Time Quantitative PCR For Minimal Residual Disease Detection In Follicular Lymphomas

BackgroundDetection of minimal residual disease (MRD) by t(14;18) Real-Time Quantitative (RQ) PCR is an important tool during clinical follow-up in patients (pts) with follicular lymphoma (FL). However, only the major breakpoint region (MBR) and minor cluster region (mcr) breakpoints have been currently exploited as MRD targets. Therefore, only 50% to 65% of pts can be assessed by t(14;18) RQ-PCR. Alternative targets such as the immunoglobulin heavy chain variable region (IGH) can be used only with limitations due to somatic hypermutation. IGH-based next-generation sequencing (NGS) might provide an alternative approach and provide increased sensitivity, specificity, accuracy and reproducibility. We performed a comparison of the two approaches in 29 FL pts. Patients and MethodsOverall, 206 samples (85 bone marrow, 114 peripheral blood, 6 stem cell aliquots and one lymph node sample) were investigated from 29 FL pts in which RQ-PCR based MRD analysis had been performed in the context of prospective clinical trials. Overall, 33 dx and 173 follow-up (FU) samples were analyzed. 23/29 pts had a PCR detectable t(14;18) rearrangement, 5 pts had a clonal IGH rearrangement only and one patient had no marker by consensus PCR. NGS was performed at Sequenta in South San Francisco. Using universal primer sets, we amplified IGH variable, diversity, and joining gene segments from genomic DNA. Amplified products were sequenced to obtain a high degree of coverage and analyzed using standardized algorithms for clonotype determination. Tumor-specific clonotypes were identified for each patient based on their high-frequency in the dx sample and then quantitated in FU samples.Overall comparability of MRD results by RQ-PCR and NGS was assessed using correlation analysis. A positive/negative discordance between two results was defined as major when the positive result was >1E-05 and minor when ≤1E-05; a quantitative discordance was defined as the presence of two positive results with a quantitative discrepancy >1 log. ResultsAll 29 pts were evaluable with at least one method. IGH NGS identified an index clone in 22/29 cases. Seven patients pts were only quantifiable by t(14;18) RQ-PCR while IGH NGS did not identify an index clone for sequencing. In all but one dx sample demonstrated low level lymphoma infiltration with MRD level below 10-3. In one of these cases, IG kappa could be successfully sequenced for MRD indicating that not only low level MRD but also somatic mutation of IGH is a potential pitfall for MRD detection by NGS in FL.15 pts were evaluable for MRD by t(14;18) RQ-PCR and NGS. In 97 FU samples, a significant concordance between MRD methods could be demonstrated (r2=0.80) (p<0.0001). Of these samples, 44 were MRD positive and 45 were MRD negative with both tools. A quantitative discordance occurred in 12/44 MRD positive samples, where MRD was higher in 7 samples and lower in 5 samples by NGS. A major discordance occurred in 4 samples where t(14;18) RQ-PCR was positive and NGS was negative. A minor discordance was detectable in 4 samples where in 2 samples t(14;18) RQ-PCR was positive and NGS was negative, and in the other 2 samples the opposite was correct.In 5 t(14;18) negative cases and one with an unusual large t(14;18) rearrangement MRD was quantified by IGH-RQ-PCR using cloned plasmids and IGH NGS. In all cases both methods also showed excellent concordance.One advantage of the IGH NGS approach is its ability to detect different IGH sequences generated by the somatic hypermutation process. We have seen in some patients a dynamic picture of the IGH clonotypes with the rise and fall of different clonotypes at different time points (Fig 1). [Display omitted] ConclusionsNGS represents a feasible tool for IGH-based MRD monitoring that allows analysis of a larger group of FL pts. Our results show that the two methods have a high level of correlation. Lymphoma infiltration of dx samples and somatic mutation of IGH is a critical point for identification of the tumor-specific clonotypes by NGS, therefore different MRD methods should complement each other to allow MRD assessment for the majority of pts. Furthermore IGH NGS sequencing has the potential to detect and track IGH evolution in FL. Disclosures:Kneba:Roche: Consultancy, Research Funding. Faham:Sequenta, Inc.: Employment, Patents & Royalties.

Next-Generation Sequencing and Real-Time Quantitative PCR For Quantification Of Low-Level Minimal Residual Disease In Acute Lymphoblastic Leukemia Of Adults

BackgroundDetection of minimal residual disease (MRD) in adult ALL is an independent risk parameter and early indicator of an impending relapse. MRD diagnostics have been incorporated in many ALL treatment protocols as a tool for pre-emptive treatment or risk group stratification. Currently, real-time quantitative (RQ)-PCR of immunoglobulin (IG) and T-cell receptor (TR) gene rearrangements is regarded as the most sensitive and standardized method to quantify MRD in BCR-ABL negative ALL. However, IG/TR oligoclonality and clonal evolution may lead to false negative results, while sensitivity varies depending on background amplification and is generally limited to 1E-05. Next-Generation Sequencing (NGS) of IG/TR gene rearrangements might overcome these limitations and potentially provide further increases in sensitivity, specificity, accuracy and reproducibility. We have performed a comparison of the two approaches on 130 diagnostic (DG), relapse (REL) and remission (FU) samples of 14 adult patients (pts) with B-cell precursor ALL. To test the NGS sensitivity, we partly selected follow-up samples for (low-level) RQ-PCR MRD positivity or a high pre-test probability of residual disease (either due to a later relapse or MRD detection in temporal relation to the analyzed sample). Patients and Methods130 samples (97 bone marrow, 31 peripheral blood, 2 stem cell apheresis; 15 DG, 107 FU, 8 REL samples) were analyzed from 14 pts with B-cell precursor ALL. IG/TR-based RQ-PCR was carried out within routine diagnostics in the context of prospective clinical trials [Brüggemann et al., Blood 2006], according to the EuroMRD criteria [van der Velden et al., Leukemia 2007] at the MRD reference laboratory in Kiel. NGS was performed at the Sequenta facilities in South San Francisco. Using universal primer sets, IGH, IGK, TRB, TRG, and TRD variable, (diversity), and joining gene segments were amplified from DG and REL DNA. PCR products were sequenced to obtain a high degree of coverage and analyzed using standardized algorithms for clonotype determination. Tumor-specific clonotypes were identified for each patient based on their high-frequency in DG samples. The presence of the tumor-specific clonotype was then quantitated in FU samples. A quantitative and standardized measure of clone level among all leukocytes was determined using internal reference DNA. Comparability of MRD results by RQ-PCR and NGS was assessed using bivariate correlations between methods analysis (software R 3.0.1 with cor.test). ResultsSanger sequencing of multiplex PCR detected 60 clonal IGH, IGK, TRB, TRG and/or TRD gene rearrangements at diagnosis (1-6/patient), NGS identified 57 index sequences (1-6/patient). Using NGS, relapse samples were analyzed for clonal evolution: 16/19 index rearrangements of relapsing pts were stable at relapse while 3/19 rearrangements (2 IGH VH-JH and 1 IGK) were lost at relapse.Based on Sanger sequence information of clonal rearrangements 1-3 RQ-PCR assays/patient were established while NGS focused on 1-4 clonal markers/patient.MRD was quantified in 107 FU in remission using both tools. A mean of 223,086±48,030 cells were analyzed per target using RQ-PCR, whereas NGS used 575,776±304,653 cells. An excellent concordance between the two methods was observed (p<0.0001, r2 = 0.974) with 46/107 samples being MRD positive and 45/107 MRD negative with both tools. Sequencing detected MRD in 13 samples that were negative by RQ-PCR whereas RQ-PCR revealed MRD in 3 NGS negative samples. All discrepancies affected samples with low MRD levels (below quantitative range (RQ-PCR) and levels below 8E-06 (NGS)) being consistent with Poisson sampling. In addition, both methods showed quantitative and qualitative inter-target differences with 11/49 RQ-PCR and 32/59 NGS positive samples being negative for at least one target illustrating the importance of focusing on more than one index sequence for RQ-PCR and NGS. ConclusionsSignificant concordance was observed between NGS and RQ-PCR, with NGS having similar or slightly better sensitivity compared to standardized RQ-PCR. This can be partly attributed to the higher number of cells analyzed by NGS and points out that sensitivity advantages afforded by the NGS platform may be achieved by higher input cell amounts. Prospective analyses of unselected cases must be performed to verify the clinical impact of low level NGS-based MRD detection. Disclosures:Pepin:Sequenta Inc.: Employment, Stockholder Other. Carlton:Sequenta Inc.: Employment, Stockholder Other. Faham:Sequenta Inc.: Employment, Stockholder Other.