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Small cell lung cancer (SCLC) represents 15% of lung cancers and is characterized by early dissemination, development of chemoresistance and a poor prognosis. A host of diverse drugs failed invariably and its mechanisms of global chemoresistance have not been characterized so far. SCLC represents the prototype of an aggressive and highly metastatic tumor which is ultimately refractory to any treatment. High numbers of circulating tumor cells (CTCs) allowed us to establish 5 CTC cell lines (BHGc7, 10, 16, 26 and UHGc5) from patients with recurrent SCLC. These cell lines exhibit the typical SCLC markers and CTCs of all patients developed spontaneously large multicellular aggregates, termed tumorospheres. Ki67 and carbonic anhydrase 9 (CAIX) staining of tumorosphere sections revealed quiescent and hypoxic cells, respectively. Accordingly, comparison of the chemosensitivity of CTC single cell suspensions with tumorospheres demonstrated increased resistance of the clusters against chemotherapeutics commonly used for treatment of SCLC. Therefore, global chemoresistance of relapsing SCLC seems to rely on formation of large tumorospheres which reveal limited accessibility, lower growth fraction and hypoxic conditions. Since similar tumor spheroids were found in other tumor types, SCLC seems to represent a unique tumor model to study the association of CTCs, metastasis and drug resistance.

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SummaryIntroduction This multicenter, open-label, phase II study was carried out to compare the efficacy and safety of cilengitide (EMD 121974), a selective inhibitor of the cell-surface integrins αVβ3 and αVβ5, with that of docetaxel in patients with advanced non-small-cell lung cancer (NSCLC). Methods Patients (n = 140) with advanced NSCLC who had failed first-line chemotherapy were randomized to cilengitide 240, 400, or 600 mg/m2 twice weekly, or docetaxel 75 mg/m2 once every 3 weeks for eight cycles. Non-progressing patients could continue cilengitide for up to 1 year. The primary endpoint was progression-free survival (PFS). No statistical tests were performed since the study was exploratory in nature and the number of patients enrolled was relatively small. Results Median PFS was 54, 63, 63, and 67 days for cilengitide 240, 400, and 600 mg/m2, and docetaxel 75 mg/m2, respectively. One-year survival rates were 13 %, 13 %, 29 %, and 27 %, respectively. The response rate (partial response only) with docetaxel was 15 %. No responses were reported in any cilengitide arm. The most frequent grade 3/4 treatment-related adverse events in the docetaxel group were leukopenia and neutropenia (experienced by 13 % of patients). Hematologic toxicity of this severity did not occur in cilengitide-treated patients. Conclusion With the highest dose of cilengitide (600 mg/m2), median PFS and 1-year survival were similar to those in patients treated with docetaxel 75 mg/m2 and there were fewer grade 3/4 treatment-related adverse events.