Genomically informed small-molecule drugs overcome resistance to a sustained-release formulation of an engineered death receptor agonist in patient-derived tumor models.

Manzari, Mandana T; Anderson, Gray R; Lin, Kevin H; Soderquist, Ryan S; Çakir, Merve; Zhang, Mitchell; Moore, Chandler E; Skelton, Rachel N et al. · Sci Adv · 2019

basic_science · Level V

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Abstract

Extrinsic pathway agonists have failed repeatedly in the clinic for three core reasons: Inefficient ligand-induced receptor multimerization, poor pharmacokinetic properties, and tumor intrinsic resistance. Here, we address these factors by (i) using a highly potent death receptor agonist (DRA), (ii) developing an injectable depot for sustained DRA delivery, and (iii) leveraging a CRISPR-Cas9 knockout screen in DRA-resistant colorectal cancer (CRC) cells to identify functional drivers of resistance. Pharmacological blockade of XIAP and BCL-X<sub>L</sub> by targeted small-molecule drugs strongly enhanced the antitumor activity of DRA in CRC cell lines. Recombinant fusion of the DRA to a thermally responsive elastin-like polypeptide (ELP) creates a gel-like depot upon subcutaneous injection that abolishes tumors in DRA-sensitive Colo205 mouse xenografts. Combination of ELP<sub>depot</sub>-DRA with BCL-X<sub>L</sub> and/or XIAP inhibitors led to tumor growth inhibition and extended survival in DRA-resistant patient-derived xenografts. This strategy provides a precision medicine approach to overcome similar challenges with other protein-based cancer therapies.

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