1. A Circulating Tumor Cell (CTC) Assay for Tracking Treatment Response in Glioma Melody Ju, Gary D Kao, David Steinmetz, Dana Patsch, Michelle Alonso-Basanta, Stephen M Hahn, Robert A Lustig, Jay F Dorsey Department of Radiation Oncology | University of Pennsylvania Abstract #1093

2. Disclosures The authors’ institution (University of Pennsylvania) has submitted a patent application based on a component of the technology presented.

3. Background Circulating tumor cell (CTC) detection may assist monitoring of radiotherapy (RT) response in patients with glioma A telomerase-based CTC assay has been previously described to be effective in glioma (MacArthur, et al. 2014). We present interim results of a prospective trial in patients with high grade glioma undergoing RT and serial CTC analysis MacArthur, KM et al. Cancer Res 2014;74:2152-2159

4. Results CTCs in patients with glioma were reliably and serially detected, irrespective of tumor mutation statuses (IDH, EGFR, EGFRvIII mutations, etc.) Increasing CTC trend was found to be significantly associated with progression by 6 months follow-up (p=0.02) CTC levels were sensitive to disease burden changes as a result of RT, re- resection, or progression Case A below illustrates how CTC levels in this patient matched radiologic evidence of initial disease response and eventual progression:

5. Conclusions CTC trends may reflect tumor progression and response to therapies such as RT or re-resection and thus usefully complement conventional follow-up and imaging methods for tracking treatment response Notable assay strengths: o Live cell detection o Application to a variety of cancers, including non-epithelial cancers o May complement existing CTC assays Future directions include: CTC isolation and genetic analysis for cancer-specific mutations (e.g. EGFR vIII and IDH mutations)

6. Gary D. Kao, MD, PhD Jay Dorsey, MD, PhD Stephen M. Hahn, MD Mariana Cooke, MD PhD Deeksha Saxena, PhD David Steinmetz Sanjay Chandrasekaran, MD Louise Aguarin Xiangsheng Xu, MD Kelly MacArthur, MD James Davis Department of Radiation Oncology Research Coordinators Clinical Collaborators: Robert Lustig, MD Charles Simone, MD Michelle Alonso-Basanta, MD, PhD Acknowledgements