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This file contains supplemental materials and methods describing protein calibrator preparation and pre-analytical variability

This file contains supplemental Figure S2: Temperature stability of analytes

This file contains supplemental Figure S3: Storage stability of analytes

Purpose: To support clinical pharmacodynamic evaluation of the Smac mimetic TL32711 (birinapant) and other apoptosis-targeting drugs, we describe the development, validation, and application of novel immunoassays for 15 cytosolic and membrane-associated proteins indicative of the induction, onset, and commitment to apoptosis in human tumors.Experimental Design: The multiplex immunoassays were constructed on the Luminex platform with apoptosis biomarkers grouped into three panels. Panel 1 contains Bak, Bax, total caspase-3, total lamin-B (intact and 45 kDa fragment), and Smac; panel 2 contains Bad, Bax–Bcl-2 heterodimer, Bcl-xL, Bim, and Mcl1; and panel 3 contains active (cleaved) caspase-3, Bcl-xL–Bak heterodimer, Mcl1–Bak heterodimer, pS99-Bad, and survivin. Antibody specificity was confirmed by immunoprecipitation and Western blot analysis.Results: Two laboratories analytically validated the multiplex immunoassays for application with core-needle biopsy samples processed to control preanalytical variables; the biologic variability for each biomarker was estimated from xenograft measurements. Studies of TL32711 in xenograft models confirmed a dose-dependent increase in activated caspase-3 6 hours after dosing and provided assay fit-for-purpose confirmation. Coincident changes in cytosolic lamin-B and subsequent changes in Bcl-xL provided correlative evidence of caspase-3 activation. The validated assay is suitable for use with clinical specimens; 14 of 15 biomarkers were quantifiable in patient core-needle biopsies.Conclusions: The validated multiplex immunoassays developed for this study provided proof of mechanism data for TL32711 and are suitable for quantifying apoptotic biomarkers in clinical trials. Clin Cancer Res; 22(4); 1000–10. ©2015 AACR.

This file contains supplemental Figure S1: Specificity of antibodies used in multiplex assays

This file contains supplemental Table S2A: Analytical validation- interlaboratory precision, and Table S2B: Fitness-for-purpose clinical utility- intertumoral biological variability

This file contains supplemental Table S3: Fitness-for-purpose clinical utility-Intratumoral biological variability

This file contains supplemental Figure S4: Correlation among multiplexed biomarkers

This file contains supplemental Table S1A: Analytical validation- sample dilution linearity, and Table S1B: Analytical validation- accuracy determined by spike recoveries

Purpose: To support clinical pharmacodynamic evaluation of the Smac mimetic TL32711 (birinapant) and other apoptosis-targeting drugs, we describe the development, validation, and application of novel immunoassays for 15 cytosolic and membrane-associated proteins indicative of the induction, onset, and commitment to apoptosis in human tumors. Experimental Design: The multiplex immunoassays were constructed on the Luminex platform with apoptosis biomarkers grouped into three panels. Panel 1 contains Bak, Bax, total caspase-3, total lamin-B (intact and 45 kDa fragment), and Smac; panel 2 contains Bad, Bax–Bcl-2 heterodimer, Bcl-xL, Bim, and Mcl1; and panel 3 contains active (cleaved) caspase-3, Bcl-xL–Bak heterodimer, Mcl1–Bak heterodimer, pS99-Bad, and survivin. Antibody specificity was confirmed by immunoprecipitation and Western blot analysis. Results: Two laboratories analytically validated the multiplex immunoassays for application with core-needle biopsy samples processed to control preanalytical variables; the biologic variability for each biomarker was estimated from xenograft measurements. Studies of TL32711 in xenograft models confirmed a dose-dependent increase in activated caspase-3 6 hours after dosing and provided assay fit-for-purpose confirmation. Coincident changes in cytosolic lamin-B and subsequent changes in Bcl-xL provided correlative evidence of caspase-3 activation. The validated assay is suitable for use with clinical specimens; 14 of 15 biomarkers were quantifiable in patient core-needle biopsies. Conclusions: The validated multiplex immunoassays developed for this study provided proof of mechanism data for TL32711 and are suitable for quantifying apoptotic biomarkers in clinical trials. Clin Cancer Res; 22(4); 1000–10. ©2015 AACR.