Abstract PO-070: New patient-derived head and neck cancer xenograft (PDX) panel for drug development, immuno-oncology and translational research

Abstract Head and neck squamous cell carcinomas (HNSCC) represent a heterogeneous group of epithelial cell malignancies arising from the upper aerodigestive tract. Despite of improved therapies, HNSCC remain a devastating disease. Oropharynx cancers are mainly attributed to infection with human papillomavirus (HPV). Since 2017, HNSCC are classified into HPV-negative and HPV-positive HNSCC. Therapies in the clinic are surgery and/or radiotherapy (RT)/radiochemotherapy (RCT) with a recurrence of about 50%. Therefore, new approaches are needed to improve long-term remission and patient survival. Recent advances in high-throughput molecular profiling have helped to identify genetic dispositions (TP53, FAT1, CDKNA2, NOTCH1 etc.) for HNSCC. We have generated and characterized a diverse panel (n = 85) of patient-derived xenografts (PDX) of HNSCC for preclinical research and immuno-oncological approaches. We successfully established 85 HNSCC PDX from fresh surgery tissue of primary and recurrent carcinomas by direct subcutaneous transplantation into immune-deficient mice. 14 HNSCC PDX were derived from HPV-positive tumors. We treated 28 HNSCC PDX with radiotherapy alone or radiochemotherapy. Heterogeneous individual responses to treatments resemble the clinical situation. For characterization, the established HNSCC PDX were treated with standard of cares (SoC) such as docetaxel, platinum compounds, cetuximab, 5-fluorouracil and investigational drugs. No correlation was observed to mutations and drug response. Molecular subtypes were determined based on gene expression data. Cetuximab response was associated with basal subtype and inflamed/mesenchymal subtype was negative predictive for cetuximab response. Further, 30 HNSCC PDX were analyzed for PD-L1 expression as suitable candidates for the evaluation of checkpoints inhibitors such as nivolumab and pembrolizumab and other novel immunotherapy approaches on humanized mice. To gain a deeper insight into the molecular biology, RNA sequencing was performed for 46 HNSCC models. Based on RNASeq data, an individual Human Leucocyte Antigen (HLA) profile of each PDX was determined and a comprehensive HLA matching analysis of the HNSCC models and 9 peripheral blood mononuclear cell (PBMC) donors was performed to enable personalized, preclinical immuno-oncology studies. Our newly and comprehensively characterized HNSCC PDX panel enables the evaluation of new targeted and immunological therapies in preclinical phase II studies. It provides an exceptional platform for the identification and validation of new targets and enables the preclinical screening of new combinations in translational research. Citation Format: Bernadette Brzezicha, Theresia Conrad, Maria Stecklum, Michael Becker, Konrad Klinghammer, Jens Hoffmann. New patient-derived head and neck cancer xenograft (PDX) panel for drug development, immuno-oncology and translational research [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PO-070.