874 A quantitative systems pharmacology model of head and neck squamous cell carcinoma: a tool for evaluating treatment outcomes for combination therapies

BackgroundHead and neck squamous cell carcinoma (HNSCC) is one of the most frequent cancers worldwide. Different approaches are applied to treat the cancer. Recently, several therapies were approved for treatment of head and neck cancers, and some are at the clinical trial stage.1–4 The aim of this study was to develop a comprehensive quantitative systems pharmacology (QSP) model of HNSCC that captures key cellular and molecular processes and allows to explore combination therapies.MethodsQSP model of HNSCC includes sub-modules describingcell life cycles of CD4, CD8, Tregs, NK and B cells, mDC, monocytes and macrophages, different subpopulations of tumor cells (in)sensitive to chemotherapies and cetuximabcell and cytokine distribution between blood, tumor, lymph nodes and peripheral tissuesantigen presentation and cytotoxicityinteraction of surface molecules in immunological synapses (e.g. PD1-PDL1)pharmacokinetics (PK) of various chemotherapies (carboplatin/cisplatin, pemetrexed, 5-fluorouracil), targeted therapy (cetuximab), and checkpoint inhibitors (pembrolizumab, atezolizumab)Effect of chemotherapies on both tumor cells and immune cellsDirect effect of cetuximab on tumor cell growth (mediated by its binding to EGFR) and its ADCC effect (mediated by activation of NK cells via formation of trimer between EGFR located on tumor cell, cetuximab and Fcg3A receptor on NK cells)The model of a reference Virtual Patient (VP) was parameterized on the wide range of in vitro and in vivo data available from the public domain. VP population was generated to simultaneously describe clinical data (RECIST criteria, TtR, DoR, PFS) for Pembro, Cetuximab, Cisplatin alone and following combinations Cisplatin+5-fluorouracil, Cetuximab+Cisplatin, Cetuximab+Cisplatin+5-fluorouracil available in public domain (figure 1).ResultsThe model of reference VP accurately describes baseline concentrations of cells and cytokines in patients with head and neck cancers and changes in immune cell numbers and surface molecule levels under various treatments. VP population was validated against following individual and combination therapies Cetuximab+Cisplatin/Carboplatin+ Pemetrexed, Pembrolizumab+Cisplatin/Carboplatin+5-fluorouracil, Pembrolizumab+Cetuximab and Atezolizumab alone. VP population was applied to explore response to combination therapies at the level of clinically measured endpoints and biomarkers. This analysis allows us to explore correlations between responder/non-responder