igk and Leukemia--Lymphocytic--Chronic--B-Cell

The clonoSEQ® Assay (Adaptive Biotechnologies Corporation, Seattle, USA) identifies and tracks unique disease-associated immunoglobulin (Ig) sequences by next-generation sequencing of IgH, IgK, and IgL rearrangements and IgH-BCL1/2 translocations in malignant B cells. Here, we describe studies to validate the analytical performance of the assay using patient samples and cell lines.. Sensitivity and specificity were established by defining the limit of detection (LoD), limit of quantitation (LoQ) and limit of blank (LoB) in genomic DNA (gDNA) from 66 patients with multiple myeloma (MM), acute lymphoblastic leukemia (ALL), or chronic lymphocytic leukemia (CLL), and three cell lines. Healthy donor gDNA was used as a diluent to contrive samples with specific DNA masses and malignant-cell frequencies. Precision was validated using a range of samples contrived from patient gDNA, healthy donor gDNA, and 9 cell lines to generate measurable residual disease (MRD) frequencies spanning clinically relevant thresholds. Linearity was determined using samples contrived from cell line gDNA spiked into healthy gDNA to generate 11 MRD frequencies for each DNA input, then confirmed using clinical samples. Quantitation accuracy was assessed by (1) comparing clonoSEQ and multiparametric flow cytometry (mpFC) measurements of ALL and MM cell lines diluted in healthy mononuclear cells, and (2) analyzing precision study data for bias between clonoSEQ MRD results in diluted gDNA and those expected from mpFC based on original, undiluted samples. Repeatability of nucleotide base calls was assessed via the assay's ability to recover malignant clonotype sequences across several replicates, process features, and MRD levels.. LoD and LoQ were estimated at 1.903 cells and 2.390 malignant cells, respectively. LoB was zero in healthy donor gDNA. Precision ranged from 18% CV (coefficient of variation) at higher DNA inputs to 68% CV near the LoD. Variance component analysis showed MRD results were robust, with expected laboratory process variations contributing ≤3% CV. Linearity and accuracy were demonstrated for each disease across orders of magnitude of clonal frequencies. Nucleotide sequence error rates were extremely low.. These studies validate the analytical performance of the clonoSEQ Assay and demonstrate its potential as a highly sensitive diagnostic tool for selected lymphoid malignancies.

Topics: Bone Marrow; Cyclin D1; Gene Rearrangement; High-Throughput Nucleotide Sequencing; Humans; Immunoglobulin Heavy Chains; Immunoglobulin lambda-Chains; Immunoglobulins; Leukemia, Lymphocytic, Chronic, B-Cell; Limit of Detection; Multiple Myeloma; Neoplasm, Residual; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Reagent Kits, Diagnostic; Translocation, Genetic

Classical t(11;14)(q13;q32) involving IGH-CCND1 is typically associated with aggressive CD5-positive mantle cell lymphoma (MCL). Recently, we identified the IGK variant of this translocation, t(2;11)(p11;q13), in three patients with a leukemic small-cell B-non-Hodgkin lymphoma. In all cases, rearrangements of the IGK and CCND1 genes were demonstrated by fluorescence in situ hybridization. Moreover, we mapped the 11q13 breakpoint of this variant translocation in the 3' region of CCND1 which contrasts with the 5' breakpoints in a standard t(11;14)(q13;q32). Expression of cyclin D1 was shown in two cases analyzed either at diagnosis or during disease progression. All three patients were asymptomatic at presentation and no initial therapy was required. One patient died of a progressive disease 58 months from diagnosis, and two patients showed stable disease after 12 months of follow-up. In two analyzed cases, mutated IGVH genes were identified. Our findings indicate that variant t(2;11)(p11;q13) does not typify a classical MCL but possibly a more indolent leukemic lymphoma originating from an antigen experienced (mutated) B cell.

Topics: Adult; Chromosomes, Human, Pair 11; Chromosomes, Human, Pair 2; Cyclin D1; Disease Progression; DNA, Neoplasm; Female; Gene Rearrangement, B-Lymphocyte, Heavy Chain; Genetic Variation; Humans; Immunoglobulin Heavy Chains; Immunoglobulin Variable Region; Immunoglobulins; In Situ Hybridization, Fluorescence; Karyotyping; Leukemia; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma, Mantle-Cell; Lymphoma, Non-Hodgkin; Male; Middle Aged; Mutation; Neoplasm Recurrence, Local; Translocation, Genetic