Abstract 3746: Novel therapeutic possibilities for chemorefractory ovarian cancer patients identified by functional ex vivo drug sensitivity testing of primary cells from ascites
Authors: Murumägi Astrid , Hirasawa Akira , Arjama Mariliina , Välimäki Katja , Yadav Bhagwan , Tang Jing , Szwajda Agnieszka , Turunen Laura , Mpindi John Patrick , Pellinen Teijo , Wennerberg Krister , Bützow Ralf , Aittokallio Tero , Kallioniemi Olli 
Published: August 2015

Ovarian cancer (OvCa) is the sixth most common cancer in women and a leading cause of death from gynecologic diseases. Poor prognosis in OvCa is due to late diagnosis and acquired resistance to conventional therapy. A significant setback for OvCa treatment is the lack of reliable biomarkers and the lack of effective targeted therapies.

Our aim is to discover novel therapeutic opportunities with approved and emerging drugs for OvCa and then translate actionable drug efficacies and combinations as personalized therapy suggestions for the clinic. We have previously pioneered drug sensitivity and resistance testing (DSRT) of patient cells from leukemias for personalized medicine and for drug repositioning (Pemovska et al., Cancer Discovery, 2013; Pemovska et al. Nature, in press, 2014). Here, we tested primary cell cultures from the ascites fluid of relapsed chemorefractory OvCa patient samples using the DSRT platform for 305 drugs, consisting of both emerging and established cancer drugs. All drugs were tested in 5 concentrations to achieve a dose-response over a 10,000-fold concentration range. Both viability and cell toxicity assays were applied and results compared to a variety of normal cells and a database of &gt;700 previously DSRT-tested cancer samples and cell lines of various types, including 30 OvCa cell lines. Genomic and transcriptomic profiling by next-gen sequencing was carried out in parallel. Most samples represent high-grade serous OvCa.

Results from 5 primary ascites cultures tested so far showed a distinct drug sensitivity profile as compared to the 30 OvCa cell lines. The results on patient cells led to the discovery of previously unanticipated therapeutic possibilities. For example, in a 51-year old chemorefractory serous OvCa patient, genomic and transcriptomic analyses revealed a fusion gene of NRG-1, a target that was recently reported to involve the NRG1/ERBB3 activation loop in OvCa (Sheng et al. Cancer Cell, 2010). We found high expression of ERBB2 and ERBB3 by RNA seq and phospho-ERBB3, phospho-ERBB2 and phospho-EGFR by immunohistochemistry. In agreement with the molecular mechanism, DSRT analysis identified significant sensitivity of patient tumor cells to EGFR inhibitors, such as erlotinib and afatinib. Furthermore, drug combination testing identified highest combinatorial potential of dasatinib with erlotinib and afatinib in both viability and cell killing assays.

In conclusion, DSRT testing together with genomic and transcriptomic profiling can identify and mechanistically validate tumor driver signals and pinpoint clinically actionable inhibitors and their combinations. Thus, this type of systems medicine profiling can significantly expand the power of current exclusively genomics-oriented personalized medicine approaches and help in drug repositioning to new indications.

Citation Format: Astrid Murumägi, Akira Hirasawa, Mariliina Arjama, Katja Välimäki, Bhagwan Yadav, Jing Tang, Agnieszka Szwajda, Laura Turunen, John Patrick Mpindi, Teijo Pellinen, Krister Wennerberg, Ralf Bützow, Tero Aittokallio, Olli Kallioniemi. Novel therapeutic possibilities for chemorefractory ovarian cancer patients identified by functional ex vivo drug sensitivity testing of primary cells from ascites. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3746. doi:10.1158/1538-7445.AM2015-3746