1438P - Trabectedin combined with Hyperthermia: Characterization of enhanced drug-efficacy in human tumor cells

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Anti-Cancer Agents & Biologic Therapy
Translational Research
Presenter Dominique Harnicek
Citation Annals of Oncology (2014) 25 (suppl_4): iv494-iv510. 10.1093/annonc/mdu354
Authors D. Harnicek1, E. Kampmann2, A. Tanovic3, Y. Guo4, E. Gallmeier4, K. Lauber5, L.H. Lindner6, R. Issels7
  • 1Helmholtz Centre Munich, German Research Centre For Environmental Health, Clinical Cooperation Group Tumor Therapy through Hyperthermia, 81377 - München/DE
  • 2Lmu München, Medizinische Klinik 3, 81377 - München/DE
  • 3Medical Affairs, PharmaMar, 08028 - Barcelona/ES
  • 4Department Of Internal Medicine Ii, University of Munich, Munich/DE
  • 5Department Of Radiation Oncology, University of Munich, Munich/DE
  • 6Dept Internal Medicine Iii, University Hospital Munich – Grosshadern, 81377 - München/DE
  • 7Tumor Therapy Through Hyperthermia, Helmholtz Centre Munich, German Research Centre for Environmental Health, 81377 - München/DE

Abstract

Aim

Trabectedin (Yondelis) is approved for the treatment of patients with advanced soft tissue sarcoma (STS) after failure of anthracyclines and ifosfamide. Its cytostatic activity is associated with the induction of DNA double-strand breaks (DSBs). Regional hyperthermia (RHT) improves chemotherapy of patients with high-risk STS (Issels, Lancet Oncol 2010). The rationale for combined treatment is that heat-mediated degradation of BRCA2 impairs DNA homologous recombination repair (HR) which is crucial for the repair of DSBs (Krawczyk, PNAS 2011). Previously, we have demonstrated that simultaneous treatment of trabectedin and RHT resulted in enhanced cytotoxicity accompanied by elevated DNA-damage (Kampmann, CTOS 2013).

Methods

For treatment, trabectedin (5-20nM) was applied for 3 hours with or without RHT (41.8°C or 43°C) for 1.5 hours. Cell cycle arrest and apoptosis were analyzed in the following human cell lines: U2Os (osteosarcoma), SW872 (liposarcoma) DLD1 (colorectal cancer) and DLD1−/-BRCA2 by Nicoletti staining and measuring caspase-activity 24h, 48h and 72h after treatment. The extent of cellular senescence was analyzed by a senescence-associated beta-galactosidase assay 72h and 144h after treatment.

Results

Trabectedin treatment induced G2 arrest which was increased and prolonged after adding RHT. Furthermore, trabectedin induced apoptosis dose dependently which was also significantly augmented by RHT. However, the relative amount of apoptosis in U2Os was only half as large as in SW872 or DLD1. Interestingly, trabectedin induced a remarkable amount of senescent cells in U2Os but not in SW872 which again was significantly augmented by RHT. In BRCA2-deficient cells, thermosensitization of trabectedin was significantly reduced.

Conclusions

Simultaneous treatment of trabectedin and RHT results in enhanced cytotoxicity accompanied by elevated DNA-damage. BRCA2-degradation and impairment of HR dependent DSB-repair are involved in thermosensitization. Here we discovered cell specific differences in induction of apoptosis or senescence which warrants further investigation.

Disclosure

A. Tanovic: Scientific writer of PharmaMar. All other authors have declared no conflicts of interest.