Structure-based Design of JOC-x, a Conjugatable Tumor Tight Junction Opener to Enhance Cancer Therapy

Abstract

Disorganized intercellular junctions are critical for maintaining the integrity of solid epithelial tumors and prevent the infiltration of oncological therapies into the bulk of the malignancy. We have developed small, recombinant proteins which bind a critical junction protein, desmoglein 2, triggering the transient and specific opening of tumor tight junctions allowing for infiltration of the tumor with immune cells, oncolytic viruses, drugs, and other therapeutics. Our new molecule, JOC- x , is a promising candidate for a new class of tumor-targeting agents that accumulate both around and within tumors and remodel the tumor microenvironment. Native cysteines were removed from the parental protein, JO-4, followed by addition of a single cysteine to allow for convenient attachment of various payloads that can be targeted directly to the tumor. Our tumor-targeting protein exhibits high avidity, minimal aggregation, and is easily purified at good yields from E. coli . For proof of concept, we demonstrate effective conjugation to biotin as a model for flexible co-targeting, addition of metal ion chelators as models for imaging and radiotherapy, and linkage of the TLR3 agonist poly(I:C) as a model immune-oncologic agent. This second-generation cancer co-therapeutic protein is optimized for activity and primed for cGMP manufacture in preparation for upcoming clinical studies.

Functional ligands for improving anticancer drug therapy: current status and applications to drug delivery systems

“…The therapeutic efficacy of anticancer drugs in solid tumors depends on the drug’s penetration into the tumor mass, affinity to the target, and retention at the site of action (Moradi Kashkooli et al., 2021 ). Epithelial cancers are characterized by tight junctions (TJs) that create obstacles to naturally occurring immune cells, antibodies, and drug therapies (Pitner et al., 2019 ). Studies have revealed a positive correlation between the upregulation of TJ proteins in solid tumors and their resistance to drug therapy (Martin, 2014 ; Pitner et al., 2019 ).…”

“…Epithelial cancers are characterized by tight junctions (TJs) that create obstacles to naturally occurring immune cells, antibodies, and drug therapies (Pitner et al., 2019 ). Studies have revealed a positive correlation between the upregulation of TJ proteins in solid tumors and their resistance to drug therapy (Martin, 2014 ; Pitner et al., 2019 ). The primary function of TJs is to mediate intercellular adhesion and polarity.…”

“…Recently, Pitner et al. ( 2019 ) developed a new class of tumor-targeting protein (from JO-4), junction opener conjugated to x (JOC-x) that can accumulate both around and within tumors and remodel the tumor microenvironment.…”

Emerging role of RNA sensors in tumor microenvironment and immunotherapy

“…ZnPP PM loaded by poly-IC could activate T lymphocytes and NK cells, and effectively repolarize TAM in B16-F10 melanoma tumor model. JOC-x is a conjugatable tumor tight junction opener, when conjugated with poly-IC, it could not only recruit and activate of CD8 + T cells by targeting DCs, but also play a tumor killing role by initiating apoptosis in tumor cells [ 133 ].…”

Properties of Adenovirus Vectors with Increased Affinity to DSG2 and the Potential Benefits of Oncolytic Approaches and Gene Therapy

“…The V239D mutation is localized in a region of the knob corresponding to an exposed loop (E-F). As this region is located at the side of the fiber knob, it is not a direct binding region to DSG2, but it is known to be critical for stabilizing DSG2 binding [23,24]. Notably, only part of the residues critical for Ad3 fiber knob binding to DSG2 are conserved in the other DSG2-interacting adenoviruses (Ad7, Ad11, Ad14 and Ad55).…”