MS32.02 Patient Derived Models (PDX and CTC-Derived)

Abstract

Patient-derived xenograft (PDX) models are a powerful preclinical tool for studying small cell lung cancer (SCLC) biology and therapeutic vulnerabilities. SCLC PDX models can be generated from biopsies or circulating tumor cells (CTCs), though these approaches can be limited by scarcity of tissue and low efficiency of tumor growth. Applying an established clinical-translational pipeline for tissue collection and an automated microfluidic platform for CTC-enrichment, we have generated over 40 PDX models. In a 24-month period, we initiated 17 biopsy-derived PDXs and 17 CTC-derived PDXs, at 89% and 38% efficiency, respectively (Drapkin et al., Cancer Discovery 2018). Whole exome sequencing showed that somatic alterations are stably maintained between patient tumors and PDXs. Early-passage PDXs maintain the genomic and transcriptional profiles of the founder PDX. We have standardized quantitative measurements of efficacy of in vivo treatments, utilizing both depth of tumor shrinkage (response) and time to tumor volume doubling (time to progression). With these approaches, we have assessed responses to both standard of care and experimental therapies across a large panel of mice. We find that sensitivity to etoposide and platinum (EP) corresponds with the treatment history of patients, and that resistance to EP corresponded to increased expression of a MYC gene signature. Similarly, responses of the PDXs to an experimental combination, olaparib and temozolomide, mirrors the responses seen in patients treated on a clinical trial (Farago et al., ASCO 2018). Biomarker analysis in this panel reveals that basal PARylation is a highly sensitive and specific predictor of response to olaparib and temozolomide. Collectively, this experience highlights the utility of PDX models in SCLC for biomarker discovery and assessment of novel therapeutic strategies. 1. Drapkin BJ, George J, Christensen CL, Mino-Kenudson M, Dries R, Sundaresan T, Phat S, Myers DT, Zong J, Igo P, Hazar-Rethinam MH, Licausi JA, Gomez-Caraballo M, Kem M, Jani KN, Azimi R, Abedpour N, Menon R, Lakis S, Heist RS, Buttner R, Haas S, Sequist LV, Shaw AT, Wong K-K, Hata A, Toner M, Maheswaran S, Haber DA, Peifer M, Dyson N, Thomas RK, Farago AF. Genomic and functional fidelity of small cell lung cancer patient-derived xenografts. Cancer Discovery 2018 May 8(5):600-615. PMID: 29483136 2. Farago AF, Drapkin BJ, Charles A, Yeap B, Heist RS, Azzoli CG, Jackman D, Marcoux P, Barbie D, Myers DT, Phat S, Zhong J, Grinnell JB, Sequist LV, Mino-Kenudson M, Maheswaran S, Haber D, Hata A, Dyson N, Shaw AT. Safety and efficacy of combination olaparib (O) and temozolomide (T) in small cell lung cancer (SCLC). American Society of Clinical Oncology Annual Meeting, June 1-5 2018. Poster presentation