Oral Presentation Advances in Neuroblastoma Research Congress 2016

The prognostic and therapeutic relevance of TERT activation in neuroblastoma (#16)

Andrea Kraemer 1 2 , Frederik Sand 1 , Janina Fischer 1 , Sandra Ackermann 1 2 , Ruth Volland 1 , Yvonne Kahlert 1 , Anne Engesser 1 , Falk Hertwig 1 , Frederik Roels 1 , Martin Peifer 3 , Frank Berthold 1 , Barbara Hero 1 , Matthias Fischer 1 2 4
  1. University Children’s Hospital of Cologne, Cologne, Germany
  2. Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
  3. Department of Translational Genomics, University of Cologne, Cologne, Germany
  4. Max Planck Institute for Metabolism Research, Cologne, Germany

Background: We recently discovered that genomic rearrangements of TERT occur in one-quarter of high-risk neuroblastoma (NB), and that both TERT-rearrangements and MYCN-amplification lead to massive telomerase activation. We therefore investigated the potential prognostic and therapeutic relevance of TERT activation in NB.

Methods: Tumor samples of 284 NB patients were analyzed by whole-genome-sequencing or break-apart FISH analysis. The in vitro growth of seven NB cell lines (TERT-rearranged, n=2; MYCN-amplified, n=2; Alternative Lengthening of Telomeres (ALT), n=3) was assessed by viable cell counting upon treatment with the telomerase inhibitors BIBR1532, costunolide or 6-thio-2’-deoxyguanosine. Tumor growth of two cell lines treated intraperitoneally with 6-thio-2’-deoxyguanosine was investigated in nude mice.

Results: In the entire cohort, we detected 33 TERT-rearrangements (11.6%; 30 high-risk and 3 intermediate-risk patients). The clinical outcome of patients whose tumors harbored TERT-rearrangements was similar to that of patients with MYCN-amplified tumors, but significantly worse than that of high-risk patients without these alterations (event-free survival, p=0.023; overall survival, p=0.055). Treatment of NB cell lines with the nucleoside analogue 6-thio-2’-deoxyguanosine led to a significant growth inhibition in both TERT-rearranged and MYCN-amplified cells in a dose dependent manner (mean IC50, 1.33 µM and 1.27 µM, respectively). By contrast, NB cells with ALT pathway activation were largely unaffected by 6-thio-2’-deoxyguanosine treatment (IC50 >10 µM each). Similar effects were observed for costunolide and BIBR1532, whereas etoposide impaired the growth of TERT-, MYCN- and ALT-positive cell lines at comparable concentrations (mean IC50, 0.55, 0.39, and 0.41 µM, respectively), emphasizing the on-target specificity of telomerase inhibitors. In addition, 6-thio-2’-deoxyguanosine significantly impaired tumor growth of TERT- and MYCN-positive cells in mouse xenograft models.

Conclusion: We demonstrate that the presence of TERT-rearrangements is a strong prognostic marker for poor outcome in neuroblastoma. Furthermore, we suggest that activated telomerase may represent a therapeutic target in NB harboring TERT-rearrangements or MYCN amplification.