Abstract 2017: Development of ultrasensitive Singulex immunoassays for CCL3 and CCL4, important biomarkers for the BTK inhibitor studies

• Published in: Cancer research (Chicago, Ill.) Vol. 75; no. 15_Supplement; p. 2017
• Main Authors: Wu, Jenny Q., Burton, Luciana, Raja, Rajiv, McCaffery, Ian, Penuel, Elicia, Darbonne, Walter
• Format: Journal Article
• Language: English
• Published: 01.08.2015
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2015-2017

Abstract Disregulation of B-Cell Receptor (BCR) leading to activation has been associated with a number of B-cell malignancies including Chronic Lymphocytic Leukemia (CLL) [1]. In response to BCR activation, B-cells secrete chemokines CCL3 and CCL4 that foster interactions between CLL cells and the leukemia microenvironment and to recruit T-cells. High levels of CCL3 have also been correlated with poor prognosis in CLL [2]. Bruton tyrosine kinase (BTK) has long been known to be a key component of B cell receptor (BCR) signaling that regulates B cell proliferation and survival. BTK inhibitors such as lbrutinib have been shown to disrupt secretion of BCR-dependent chemokines (CCL3/CCL4) and thereby reduce plasma concentrations in patients [3]. Consequently, these chemokines have been measured as pharmacodynamic biomarkers in a number of studies of molecules that inhibit BCR signaling [3]. However, baseline CCL3/CCL4 levels in CLL patients vary widely and are less than 10 pg/ml in a large proportion of patient samples, making detection of these cytokines in clinical samples challenging using existing immunoassays. In an effort to improve sensitivity of CCL3/CCL4 measurements in plasma samples, we developed ultrasensitive assays for CCL3 and CCL4 using the Singulex immunoassay platform. A direct comparison of multiple, commercially available immunoassays technologies and our optimized CCL3/CCL4 Singulex assay were performed using plasma samples from both healthy donors and CLL patients. Singulex proprietary Single Molecule Counting (SMCTM) technology combining digital counting enables the quantification of CCL3 and CCL4 with sensitivity of 0.37pg/ml and 0.15pg/ml respectively in plasma. This ultrasensitive assay has the potential to enable more robust and quantifiable measurements of CCL3 and CCL4 in the context of clinical studies testing BTK inhibitors. Citation Format: Jenny Q. Wu, Luciana Burton, Rajiv Raja, Ian McCaffery, Elicia Penuel, Walter Darbonne. Development of ultrasensitive Singulex immunoassays for CCL3 and CCL4, important biomarkers for the BTK inhibitor studies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2017. doi:10.1158/1538-7445.AM2015-2017