Impact of Disseminated Neuroblastoma Cells on the Identification of the Relapse-Seeding Clone

Abstract

Purpose: Tumor relapse is the most frequent cause of death in stage 4 neuroblastomas. Since genomic information on the relapse precursor cells could guide targeted therapy, our aim was to find the most appropriate tissue for identifying relapse-seeding clones.Experimental design: We analyzed 10 geographically and temporally separated samples of a single patient by SNP array and validated the data in 154 stage 4 patients.Results: In the case study, aberrations unique to certain tissues and time points were evident besides concordant aberrations shared by all samples. Diagnostic bone marrowderived disseminated tumor cells (DTCs) as well as the metastatic tumor and DTCs at relapse displayed a 1q deletion, not detected in any of the seven primary tumor samples. In the validation cohort, the frequency of 1q deletion was 17.8%, 10%, and 27.5% in the diagnostic DTCs, diagnostic tumors, and DTCs at relapse, respectively. This aberration was significantly associated with 19q and ATRX deletions. We observed a significant increased likelihood of an adverse event in the presence of 19q deletion in the diagnostic DTCs.Conclusions: Different frequencies of 1q and 19q deletions in the primary tumors as compared with DTCs, their relatively high frequency at relapse, and their effect on event-free survival (19q deletion) indicate the relevance of analyzing diagnostic DTCs. Our data support the hypothesis of a branched clonal evolution and a parallel progression of primary and metastatic tumor cells. Therefore, searching for biomarkers to identify the relapse-seeding clone should involve diagnostic DTCs alongside the tumor tissue. Clin Cancer Res; 23(15); 4224-32.Ó2017 AACR.

Neuroblastoma cells undergo transcriptomic alterations upon dissemination into the bone marrow and subsequent tumor progression

“…For 34 enriched DTCs, we used one aliquot of the samples for genome analysis that was performed earlier . The data were analyzed with the ChAS software (Affymetrix).…”

“…Although chromosome 19 deletions are only rarely observed in neuroblastoma, several studies reported deletions or copy neutral loss of heterozygosity (cnLOH) in primary tumors at low frequency . Interestingly, our recent study revealed a higher frequency of partial chromosome 19 deletions in DTCs of relapse patients as compared to diagnostic DTCs . Although most reported chromosome 19 deletions in our and other studies affected the q ‐arm, we found most of the differentially expressed genes to be encoded by the p‐arm.…”

“…For 34 enriched DTCs, we used one aliquot of the samples for genome analysis that was performed earlier. 13,15 The data were analyzed with the ChAS software (Affymetrix). SNP array data analyzed for these studies are available on the GEO repository under the accession number GSE84291, and the corresponding GEO identifier can be found in the Supporting Information Table S3.…”

“…In our recent studies, we have shown that BM‐derived DTCs are suitable for genomic and transcriptomic analyses . Furthermore, it has been demonstrated that DTCs can be highly informative regarding the identification of the relapse‐seeding clone . However, little is known about gene expression changes occurring in DTCs upon dissemination and tumor progression.…”

“…13,14 Furthermore, it has been demonstrated that DTCs can be highly informative regarding the identification of the relapse-seeding clone. 15 However, little is known about gene expression changes occurring in DTCs upon dissemination and tumor progression. So far, only a single group has performed gene expression profiling of BM-derived DTCs from 11 neuroblastoma patients by microarray analysis.…”