Circulating Tumor Cells: Application as a Biomarker for Molecular Characterization and Predictor of Survival in an All-Comer Solid Tumor Phase I Clinical Study |
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Authors: | Haifeng Bao Patricia A. Burke Jiaqi Huang Xiaoru Chen Philip Z. Brohawn Yihong Yao Robert J. Lechleider Robert S. Sikorski Manuela Buzoianu Jianliang Zhang Xiaoqing Shi Laura K. Richman Theresa M. LaVallee |
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Affiliation: | 1. Department of Translational Sciences, MedImmune LLC, Gaithersburg, Maryland, United States of America.; 2. Formerly at Clinical Development, MedImmune LLC, Gaithersburg, Maryland, United States of America.; 3. Clinical Development, MedImmune LLC, Gaithersburg, Maryland, United States of America.; Queen Elizabeth Hospital, Hong Kong, |
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Abstract: | PurposeClinical development of cancer drugs has a low success rate. Prognostic and predictive biomarkers using minimally invasive approaches hold promise for increasing the probability of success by enabling disease characterization, patient selection and early detection of drug treatment effect. Enumeration and molecular characterization of circulating tumor cells (CTC) may address some of these needs, and thus were evaluated for utility in a Phase I solid tumor clinical study.Experimental DesignBlood samples for CTC analysis were obtained from 24 cancer patients in a multi-center all-comer Phase I study of MEDI-575, a novel anti-PDGFRα antibody. Samples were taken at screening and analyzed for enumeration of CTC using the CellSearch® platform and for molecular characterization using a novel quantitative RT-PCR assay.ResultsFifty-nine percent of the patients showed at least 1 CTC per 7.5 ml of blood at baseline. Progression-free survival (PFS) and overall survival (OS) of patients with 0 CTCs at baseline were longer than PFS and Os for patients with 1-3 and >3 CTCs (8.8 versus 1.4 and 1.3 months PFS, P = 0.02; 9.0 vs 7.4 and 3.5 months OS, P = 0.20, respectively). Patients with 0 CTC showed a greater percentage of stable disease than the other 2 groups with 1-3 and >3 CTCs (57% vs 29% and 0%). The multimarker qRT-PCR method detected CTC in 40% of the patients, and 80% of these patients were positive for pre-selected drug target genes.ConclusionCTC enumeration of patients in an all-comer study is feasible and may allow for patient stratification for PFS and Os to evaluate the clinical response of investigational agents. Gene expression profiling of isolated CTC may provide a means for molecular characterization of selected tumor targets. |
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