Genetic heterogeneity in primary and relapsed mantle cell lymphomas: Impact of recurrent CARD11 mutations

Abstract

The genetic mechanisms underlying disease progression, relapse and therapy resistance in mantle cell lymphoma (MCL) remain largely unknown. Whole-exome sequencing was performed in 27 MCL samples from 13 patients, representing the largest analyzed series of consecutive biopsies obtained at diagnosis and/or relapse for this type of lymphoma. Eighteen genes were found to be recurrently mutated in these samples, including known (ATM, MEF2B and MLL2) and novel mutation targets (S1PR1 and CARD11). CARD11, a scaffold protein required for B-cell receptor (BCR)-induced NF-κB activation, was subsequently screened in an additional 173 MCL samples and mutations were observed in 5.5% of cases. Based on in vitro cell line-based experiments, overexpression of CARD11 mutants were demonstrated to confer resistance to the BCR-inhibitor ibrutinib and NF-κB-inhibitor lenalidomide. Genetic alterations acquired in the relapse samples were found to be largely non-recurrent, in line with the branched evolutionary pattern of clonal evolution observed in most cases. In summary, this study highlights the genetic heterogeneity in MCL, in particular at relapse, and provides for the first time genetic evidence of BCR/NF-κB activation in a subset of MCL.

Acquired mutations associated with ibrutinib resistance in Waldenström macroglobulinemia

“…CARD11 mutations in the coil-coiled domain were observed in MYD88-mutated activated B-cell subtype of diffuse large B-cell lymphoma patients, and are associated with in vitro, as well as primary clinical resistance to ibrutinib in activated B-cell diffuse large B-cell lymphoma and MCL. [26][27][28] The variant observed by us has not been previously described and resides outside the coil-coiled domain of CARD11. Functional studies are therefore needed to characterize this novel mutation and its potential contribution to ibrutinib resistance.…”

Clinical and functional impact of recurrent S1PR1 mutations in mantle cell lymphoma

“…For personal use only on June 6, 2019. by guest www.bloodadvances.org From Two hundred samples in total, including cases characterized by WES. 17 AA, amino acid; N.A., not applicable; R, relapse.…”

“…The coding region of S1PR1 (exon 2) was analyzed in 200 (diagnostic and/or relapse) samples from 179 MCL patients (including 6 samples that have been sequenced by WES and described by Wu et al 17 ) diagnosed between 1997 and 2013. Paired normal DNA from 4 S1PR1 mutated samples that were sequenced by WES did not show mutations in the S1PR1 germ line.…”

“…For the remaining cases that were Sanger sequenced, paired normal DNA was not available, and thus we cannot ascertain the somatic origin of S1PR1 mutations in these cases. However, in-depth analyses were made to subtract all previously known somatic variants as described by Wu et al 17 Information on age, sex, stage, and survival status were collected from patients' records. Genomic DNA was extracted from peripheral blood, frozen tumor samples, or viability frozen cells using DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany) or GenElute Mammalian Genomic DNA Miniprep Kit (Sigma, Taufkirchen, Germany), following the manufacturers' instructions.…”

“…Although few mutations have been hitherto identified in homing/egress receptors, we recently reported S1PR1 as 1 of 25 recurrent mutations by whole exome sequencing (WES) and Sanger sequencing of primary and relapsed tumors from 13 MCLs. 17 In the current study, we aimed to investigate the frequency and the possible clinical and functional impact of S1PR1 mutations in MCL. We thus extended the screening of the coding region of S1PR1 in 200 MCL samples from 179 patients and provide novel insight into functional consequences of these mutations.…”