Abstract 952: Ex vivo drug testing identifies a potentially effective drug in 94% of cases for 403 patients in 42 tumor types

Abstract Objective: To determine whether patient derived tumor cells (PDTC) could be derived from a variety of solid tumors and used to select effective therapies, we developed a CLIA certified assay, the PARIS® test, to quantify drug sensitivities using PDTCs. Methods: Oncologists referred patients for the PARIS® test and patients had the option to consent to SEngine Precision Medicine’s IRB protocol. Samples were obtained from multiple cancer centers across the US and abroad. Patients were at all stages in their clinical journey ranging from treatment naïve to late stage, recurrent/refractory disease settings. Fresh specimens obtained from surgical resections, core biopsies, or body fluids arrived at our CLIA laboratory within 48 hrs from collection. Tumor origin and driver mutations were confirmed by IHC or DNA sequence in 88% of the cases. Results: PDTCs derived from 403 patients diagnosed with 42 different solid tumor types, including both common and rare tumors, were subjected to the PARIS® assay. An average of 67 oncology drugs (ranging from 6-307), including chemotherapies and targeted agents, were tested for each patient sample. A report ranking drug sensitivities was provided to the oncologist with an average turnaround time of less than 3 weeks. Drug sensitivity was classified as exceptional/good, moderate/low and no responses. Remarkably, 94. 2% of the PDTCs exhibited selective exceptional/good responses to at least one, and typically several drugs, despite the majority of PDTCs being derived from patients with drug resistant, metastatic disease. The drug sensitivity profiles showed highly individualized responses as well as tumor type specificity. While known biomarkers/drug sensitivity associations were confirmed, many samples exhibited sensitivity to targeted agents in the absence of known biomarkers. For example, HER2+ breast cancers demonstrated sensitivity to HER2/EGFR inhibitor and a subset of luminal B and triple negative breast cancers demonstrated HER2/EGFRi responses without underlying genetic alterations. Functional testing was also useful in the rare tumor types. For example, low grade serous ovarian cancer (LGSOC) cells, differentiated from high grade by their response to specific receptor tyrosine kinase inhibitors and estrogen antagonists, but a poor response to standard of care, as is observed in the clinic. Three patients with LGSOC that were treated with the PARIS test top scoring drugs had a positive clinical response and cases from other tumor types will be presented. Conclusions: Functional testing of PDTCs from both common and rare tumor types is feasible, even for those that have failed standard of care. We provide an unprecedented view of patient-specific, actionable vulnerabilities to current oncology drugs. Personalization of cancer care will require improved access to off-label drugs. Citation Format: Rachele Rosati, Alex C. Rajevski, Payel Chatterjee, Lauren R. Appleyard, Ana Cristina Cordero Schmidt, Shalini Pereira, Robert L. Diaz, Brady Bernard, Brady Bernard, Carla Grandori, Christopher J. Kemp. Ex vivo drug testing identifies a potentially effective drug in 94% of cases for 403 patients in 42 tumor types abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 952.