title: Analysis and variability of TGFbeta measurements in cancer patients with skeletal metastases.
abstract: Transforming growth factor beta (TGFbeta) plays an important role in cancer, but accurate measurement of circulating TGFbeta is complicated by the high TGFbeta content of platelets which can release TGFbeta ex vivo. We evaluated the use of citrate-theophylline-adenosine-dipyridamole (CTAD) tubes to reduce preanalytical variation in TGFbeta measurements caused by ex vivo platelet activation. CTAD substantially reduced ex vivo platelet activation relative to traditional plasma collections in normal donors, which correlated with a decrease in measured TGFbeta levels. We show that TGFbeta levels are elevated in the majority of cancer patients with skeletal metastases, and that within-patient variability of these levels is relatively low over several weeks. Patients with elevated TGFbeta could be subdivided into groups with or without evidence of platelet contribution to measured TGFbeta levels. The use of CTAD tubes allows a better determination of a patient's TGFbeta status, and may improve classification of patients with oncologic disease.
authors.affiliation: Eli Lilly and Company Research Laboratories, Lilly Corporate Center, Indianapolis, IN, USA;
authors.forename: Peter J
authors.initials: PJ
authors.lastname: O'Brien
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ramanathan
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Yingling
authors.forename: Jose
authors.initials: J
authors.lastname: Baselga
authors.forename: Mace L
authors.initials: ML
authors.lastname: Rothenberg
authors.forename: Michael
authors.initials: M
authors.lastname: Carducci
authors.forename: Thomas
authors.initials: T
authors.lastname: Daly
authors.forename: Dorothy
authors.initials: D
authors.lastname: Adcock
authors.forename: Michael
authors.initials: M
authors.lastname: Lahn
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