Abstract 4153: Arrayed microinjection of a ubiquitin activating enzyme inhibitor induces PD biomarker effects predictive of in vivo tumor responses to systemic drug delivery.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Presage technology enables simultaneous analysis of multiple cancer drug candidates, drug concentrations, and drug combinations within a single living tumor. The platform employs arrayed tumor microinjection technology that delivers multiple spatially defined “threads” of drug directly into discreet portions of a tumor. This enables rapid, reliable, and internally controlled cross comparisons of multiple cancer therapeutics using screening quantities of drug in an in vivo setting in which the local tumor microenvironment is maintained. Here, as an example, we apply the platform to investigate tumor responsiveness to an inhibitor of the ubiquitin activating enzyme UBA1 from Millennium Pharmaceuticals. The ubiquitin activating enzyme UBA1 regulates ubiquitin activation and subsequent polyubiquitination of proteins necessary for their degradation by the proteasome, and functionally impacts cell signaling, DNA damage repair and cell cycle progression. In vivo tumor responses were evaluated in two human xenograft models, WSU-DLCL2 and MCF-7, grown as flank tumors in immune-compromised mice. Microdosing of multiple concentrations of the UBA1 inhibitor (UBAi) into both models led to localized, easily detectable, and drug concentration-dependent biomarker changes indicative of ubiquitin pathway perturbation in the area proximal to injected drug. This included loss of poly-ubiquitin, accompanied by the expected accumulation of cMyc in tumor regions exposed to the UBAi. Localized time-dependent tumor cell death responses were observed following pathway perturbation as quantified by staining for cleaved caspase-3 and gamma-H2AX staining. Furthermore, pathological evidence of UBAi-induced cell death was clearly visible in both tumor models upon histological examination of H&E stained slides. These results highlight the capacity of the Presage platform to perform multiplexed drug studies in live tumor models. This capability could readily be expanded for use in validating additional biomarker hypotheses, indication finding studies, or for efficient identification of novel drug combinations. Citation Format: Beryl A. Hatton, Marc Grenley, Nathan Hedin, Nathan Caffo, Marc L. Hyer, Mark Manfredi, Stephen Blakemore, Richard A. Klinghoffer, Neil Bence. Arrayed microinjection of a ubiquitin activating enzyme inhibitor induces PD biomarker effects predictive of in vivo tumor responses to systemic drug delivery. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4153. doi:10.1158/1538-7445.AM2013-4153