Baseline identification of clonal V(D)J sequences for DNA-based minimal residual disease detection in multiple myeloma.

Even H Rustad,Elli Papaemmanuil,Venkata D Yellapantula,Theresia Akhlaghi,Jeffrey E Miller,Ola Landgren,Malin Hultcrantz,Austin Jacobsen,Caleb Ho,Sean M Devlin,Denise Chen,Mikhail Roshal,Ying Huang,Akshar Patel,Maria E Arcila,Noel F C C De Miranda

doi:10.1371/journal.pone.0211600

Abstract

Tracking of clonal immunoglobulin V(D)J rearrangement sequences by next generation sequencing is highly sensitive for minimal residual disease in multiple myeloma. However, previous studies have found variable rates of V(D)J sequence identification at baseline, which could limit tracking. Here, we aimed to define the factors influencing the identification of clonal V(D)J sequences. Bone marrow mononuclear cells from 177 myeloma patients underwent V(D)J sequencing by the LymphoTrack assays (Invivoscribe). As a molecular control for tumor cell content, we sequenced the samples using our in-house myeloma panel myTYPE. V(D)J sequence clonality was identified in 81% of samples overall, as compared with 95% in samples where tumor-derived DNA was detectable by myTYPE. Clonality was detected more frequently in patients with lambda-restricted disease, mainly because of increased detection of kappa gene rearrangements. Finally, we describe how the tumor cell content of bone marrow aspirates decrease gradually in sequential pulls because of hemodilution: From the initial pull used for aspirate smear, to the final pull that is commonly used for research. In conclusion, baseline clonality detection rates of 95% or higher are feasible in multiple myeloma. Optimal performance depends on the use of good quality aspirates and/or subsequent tumor cell enrichment.

Highlights

Achieving minimal residual disease (MRD) negativity after initial treatment for multiple myeloma is strongly associated with prolonged progression free (PFS) and overall survival (OS)[1,2,3,4,5]
MRD negativity after initial therapy is an important predictor of PFS and OS in patients with multiple myeloma [5,6,7,8]
We show that clonality detection rates of at least 95% are feasible in multiple myeloma when the sample quality is good, and describe how disease biology and sample quality together influence the probability of clonality detection

Summary

Introduction

Achieving minimal residual disease (MRD) negativity after initial treatment for multiple myeloma is strongly associated with prolonged progression free (PFS) and overall survival (OS)[1,2,3,4,5]. Emerging evidence shows prolonged PFS when raising the bar for MRD negativity to 10−6 (i.e. less than 1 tumor cell in 1 000 000 bone marrow cells), compared to the current IMWG definition [6,7,8]. There is lack of standardization across laboratories, concerning antibody panels, gating strategies and the number of cells analyzed [13, 14]. This translates into variable sensitivity of MRD testing, which is most often between 1 tumor cell in 10 000 (10−4) bone marrow cells, and 1 in 100 000 cells (10−5) [3, 13, 14]

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