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SummaryPatients with cancer of unknown primary (CUP) carry the double burden of an aggressive disease and reduced access to therapies. Experimental models summing up CUP features are pivotal for CUP biology investigation and drug testing. We derived two CUP cell lines (CUP#55 and #96), and corresponding patient-derived xenografts (PDXs), from ascites tumor cells. CUP cell lines and PDXs underwent histological, immune-phenotypical, molecular, and genomic characterization confirming the features of the original tumor. Genetic testing and FISH analysis identified FGFR2 amplification as therapeutic target in tumor tissues and patient-derived models. Drug-screening assays were performed to test the activity of FGFR2 targeting drug BGJ-398 (infigratinib) and the combination treatment with the MEK inhibitor trametinib, which proved to be synergic and exceptionally active, bothin vitroandin vivo. This study brings personalized therapy closer to CUP patients and paves the way to future applications of personalized medicine for metastatic patients with adverse prognosis.

Introduction: Skin cancer is the most common type of cancer and is classified in melanoma and non-melanoma cancers, which include basal cell, squamous cell, and Merkel cell carcinoma. Specific microRNAs are dysregulated in each skin cancer type. MicroRNAs act as oncogene or tumor suppressor gene regulators and are actively released from tumor cells in the circulation. Cell-free microRNAs serve many, and possibly yet unexplored, functional roles, but their presence and abundance in the blood has been investigated as disease biomarker. Indeed, specific microRNAs can be isolated and quantified in the blood, usually in serum or plasma fractions, where they are uncommonly stable. MicroRNA levels reflect underlying conditions and have been associated with skin cancer presence, stage, evolution, or therapy efficacy. Areas covered: In this review, we summarize the state of the art on circulating microRNAs detectable in skin cancer patients including all the studies that performed microRNA identification and quantification in the circulation using appropriate sample size and statistics and providing detailed methodology, with a specific focus on diagnostic and prognostic biomarkers. Expert Opinion: Circulating microRNAs display a relevant biomarker potential. We expect the development of methodological guidelines and standardized protocols for circulating miRNA quantification in clinical settings.

Patients with occult primary cancer or cancer of unknown primary (CUP) carry the double burden of an aggressive disease and reduced access to therapies, which are typically tumor-type oriented. Moreover, experimental in-vitro and in-vivo models summing up CUP features and heterogeneity are currently unavailable. We derived and expanded two CUP cell lines, and corresponding patient-derived xenografts (PDXs), from ascites tumor cells. CUP cell lines, one spontaneously growing as organoid, and PDXs were subjected to histological, immune-phenotypical, molecular and genomic (CNV and target sequencing) characterization to show their ability to recapitulate the original tumor. MicroRNA profile and genomic information were used to identify a possible primary site and patient-specific therapeutic approaches. Data on CUP most frequently altered genes were used to design a custom CUP-specific, 92-gene panel for target NGS analysis with Sure Select XS technology (Agilent Technology). Drug-screening assays were performed in vitro and in vivo on two models targeting the most promising actionable pathways. We obtained unexpected and promising results on drug combinations efficacy. This study brings personalized therapy closer to CUP patients and paves the way to future applications of personalized medicine for metastatic patients with adverse prognosis. This work was supported by grants from the Italian Association for Cancer Research (AIRC) to MF (IG 18464). Citation Format: Noemi Laprovitera, Claudia Fumarola, Elisa Porcellini, Stefano Cairo, Giulia Gallerani, Francesco Gelsomino, Irene Salamon, Maria Naddeo, Andrea Ardizzoni, Andrea Cavazzoni, Manuela Ferracin. Cancer of Unknown Primary: novel therapeutic opportunities from patient-derived cell cultures and in vivo models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3011.