Nizar Hami

There remains an unmet need for preclinical models to enable personalized therapy for ovarian cancer (OC) patients. Here we evaluate the capacity of patient-derived organoids (PDOs) to predict clinical drug response and functional consequences of tumor heterogeneity. We included 36 whole-genome-characterized PDOs from 23 OC patients with known clinical histories. OC PDOs maintain the genomic features of the original tumor lesion and recapitulate patient response to neoadjuvant carboplatin/paclitaxel combination treatment. PDOs display inter- and intrapatient drug response heterogeneity to chemotherapy and targeted drugs, which can be partially explained by genetic aberrations. PDO drug screening identifies high responsiveness to at least one drug for 88% of patients. PDOs are valuable preclinical models that can provide insights into drug response for individual patients with OC, complementary to genetic testing. Generating PDOs of multiple tumor locations can improve clinical decision making and increase our knowledge of genetic and drug response heterogeneity.

Abstract Purpose There remains an unmet need for preclinical models to enable personalized therapy for ovarian cancer (OC) patients. Recently, patient-derived organoid (PDO) cultures of patients with OC have been established that faithfully represent the histopathological features and genomic landscape of the patient tumor. In this study, we evaluate the capacity of OC PDOs to predict clinical drug response and functional consequences of tumor heterogeneity. Experimental design 36 genomically characterized PDOs from 23 patients with known clinical histories were exposed to chemotherapeutics and targeted drugs. Results OC PDOs maintained genomic features of the original tumor lesion and recapitulated patient response to neoadjuvant carboplatin and paclitaxel combination treatment, according to distinct clinical outcomes (histopathological, biochemical and radiological). PDOs displayed inter-as well as intrapatient drug response heterogeneity, which could in part be explained by genetic aberrations. All PDOs were resistant to PARP-inhibitors, in accordance with homologous recombination pathway fidelity and genome-wide mutation context. KRAS, BRAF and NRAS mutation status predicted response to BRAF-inhibitor vemurafenib and pan-HER-inhibitor afatinib, and explained differential response among four PDOs derived from distinct tumor locations of an individual patient. Importantly, PDO drug screening identified sensitivity to at least one drug for the majority of patients (88%). Conclusions OC PDOs are a valuable preclinical model system that can provide insights in drug response for individual patients with OC, complementary to genetic testing. Generating PDOs of multiple tumor locations can improve clinical decision making and increase our knowledge on genetic and drug response heterogeneity.

// Jasmin B. Post 1, 2 , Nizar Hami 1, 2 , Alexander E.E. Mertens 1, 2 , Suraya Elfrink 1, 2 , Johannes L. Bos 1, 2 and Hugo J.G. Snippert 1, 2 1 Center for Molecular Medicine, Section Molecular Cancer Research, University Medical Center Utrecht, Utrecht, The Netherlands 2 Oncode Netherlands, Institute Netherlands, Office Jaarbeurs Innovation Mile, Utrecht, The Netherlands Correspondence to: Hugo J.G. Snippert, email: H.J.G.Snippert@umcutrecht.nl Keywords: NF1; RASGAP; anti-EGFR therapy resistance; cancer progression; colorectal cancer Received: December 12, 2018      Accepted: February 01, 2019      Published: February 15, 2019 ABSTRACT Anti-EGFR therapy is used to treat metastatic colorectal cancer (CRC) patients, for which initial response rates of 10–20% have been achieved. Although the presence of HER2 amplifications and oncogenic mutations in KRAS, NRAS, and BRAF are associated with EGFR-targeted therapy resistance, for a large population of CRC patients the underlying mechanism of RAS-MEK-ERK hyperactivation is not clear. Loss-of-function mutations in RASGAPs are often speculated in literature to promote CRC growth as being negative regulators of RAS, but direct experimental evidence is lacking. We generated a CRISPR-mediated knock out panel of all RASGAPs in patient-derived CRC organoids and found that only loss of NF1, but no other RASGAPs e.g. RASA1, results in enhanced RAS-ERK signal amplification and improved tolerance towards limited EGF stimulation. Our data suggests that NF1-deficient CRCs are likely not responsive to anti-EGFR monotherapy and can potentially function as a biomarker for CRC progression.