Biology subjects

Staben, S. T.

Publications and source records attributed to Staben, S. T..

4 recordsLinked to original sources

bioRxiv2025

Catalytic degradation of circulating targets with FcRn-mediated cycling LYTACs

Circulating proteins are common targets for the discovery of occupancy-based inhibitors including monoclonal antibodies. Effective inhibition of target pathogenicity with blocking approaches, however, is often challenged by target parameters that lead to insufficient occupancy and/or incomplete pharmacology limited by only single site binding. Extracellular targeted protein degradation approaches, such as lysosomal targeting chimeras (LYTACs), offer an opportunity to minimize these challenges by an event-driven mechanism that selectively, thoroughly and irreversibly eliminates drivers of disease. First generation LYTACs, designed to traffic to the lysosome, show limited durability since the therapeutic is degraded along with the target protein of interest. Here we describe cataLYTACs, which overcome this limitation by combining stabilized asialoglycoprotein (ASGPR) ligands, pH-sensitive target binding and recycling via the neonatal Fc receptor (FcRn). These cataLYTACs degraded superstoichiometric levels of a target protein, IgE, in vitro and demonstrated deep and sustained clearance of human IgE in mouse models. In non-human primates, cataLYTACs resulted in >98% clearance of circulating endogenous IgE for 2 weeks and outperformed the standard of care blocking antibody, omalizumab (Xolair(R)), in both free IgE elimination and duration of action. CataLYTACs represent a new therapeutic modality for a wide range of disease states driven by circulating factors, with the potential for superior efficacy and duration of action compared to traditional inhibitors.

cell biology↗

bioRxiv2024

Engineering ERα degraders with pleiotropic ubiquitin ligase ligands maximizes therapeutic efficacy by co-opting distinct effector ligases

Proximity-inducing compounds that modulate target protein homeostasis are an emerging therapeutic strategy [1]. While the inherent complexity of these bifunctional compounds poses challenges for rational design and bioavailability, their composition also provides opportunities to co-opt specific cellular proteins to maximize therapeutic impact. Here, we systematically evaluate the cellular efficacy, biophysical mechanisms, and therapeutic benefits of a series of bifunctional degrader compounds, that are all engineered with the Estrogen Receptor-alpha (ER)-inhibitor endoxifen linked to different bioactive ubiquitin ligase ligands. Bifunctional ER degraders that incorporate CRL4-CRBN-binding ligands promoted the most potent ER degradation, whereas those incorporating either CRL2-VHL- or IAP-binding ligands maximized the depth of ER degradation. Notably, ER degraders containing pan-IAP antagonist ligands significantly decreased the proliferation of ER-dependent cells relative to clinical-stage ER-degraders, including the SERDs fulvestrant and GDC-9545 and the bifunctional degrader ARV-471. Mechanistic studies revealed that pan-IAP antagonist-based ER degraders uniquely promote TNF-dependent cell death, unlike the clinical-stage comparators. Remarkably, the pan-IAP antagonist-ER-degraders co-opt distinct effector ligases to achieve dual therapeutic effects: they harness XIAP within tumor cells to promote ER degradation, and activate cIAP1/2 within tumor and immune cells to induce TNF that drives tumor cell death. Our studies demonstrate a broader concept that co-opting the discrete functions of a selected set of cellular effectors, while simultaneously modulating therapeutic target protein homeostasis, are dual strategies that can be leveraged to maximize the efficacy of induced proximity therapeutics.

cancer biology↗

bioRxiv2021

RTK-dependent inducible degradation of mutant PI3K alpha drives GDC-0077 (Inavolisib) efficacy

PIK3CA is one of the most frequently mutated oncogenes; the p110 protein it encodes plays a central role in tumor cell proliferation and survival. Small molecule inhibitors targeting the PI3K p110 catalytic subunit have entered clinical trials, with early-phase GDC-0077 (Inavolisib) studies showing anti-tumor activity and a manageable safety profile in patients with PIK3CA-mutant, hormone receptor-positive breast cancer as a single agent or in combination therapy. Despite this, preclinical studies have shown that PI3K pathway inhibition releases negative feedback and activates receptor tyrosine kinase signaling, reengaging the pathway and attenuating drug activity. Here we discover that GDC-0077 and taselisib more potently inhibit mutant PI3K pathway signaling and cell viability through unique HER2-dependent degradation. Both are more effective than other PI3K inhibitors at maintaining prolonged pathway suppression, resulting in enhanced apoptosis and greater efficacy. This unique mechanism against mutant p110 reveals a new strategy for creating inhibitors that specifically target mutant tumors with selective degradation of the mutant oncoprotein and also provide a strong rationale for pursuing PI3K degraders in patients with HER2-positive breast cancer.

cancer biology↗

bioRxiv2019

MCC950/CRID3 potently targets the NACHT domain of wildtype NLRP3 but not disease-associated mutants for inflammasome inhibition

The NLRP3 inflammasome drives pathological inflammation in a suite of autoimmune, metabolic, malignant and neurodegenerative diseases. Additionally, NLRP3 gain-of-function point mutations cause systemic periodic fever syndromes that are collectively known as cryopyrin-associated periodic syndromes (CAPS). There is significant interest in the discovery and development of diarylsulfonylurea Cytokine Release Inhibitory Drugs (CRIDs) such as MCC950/CRID3, a potent and selective inhibitor of the NLRP3 inflammasome, for the treatment of CAPS and other diseases. However, drug discovery efforts have been constrained by the lack of insight in the molecular target and mechanism by which these CRIDs inhibit the NLRP3 inflammasome. Here, we show that the NACHT domain of NLRP3 is the molecular target of diarylsulfonylurea inhibitors. Interestingly, we find photoaffinity labelling of the NACHT domain requires an intact (d)ATP-binding pocket and is substantially reduced for most CAPS-associated NLRP3 mutants. In concordance, MCC950/CRID3 failed to inhibit NLRP3- driven inflammatory pathology in two mouse models of CAPS. Moreover, it abolished circulating levels of interleukin (IL)-1{beta} and IL-18 in LPS-challenged wildtype mice but not in Nlrp3L351P knock-in mice and ex vivo-stimulated mutant macrophages. These results identify wildtype NLRP3 as the molecular target of MCC950/CRID3, and show that CAPS-related NLRP3 mutants escape efficient MCC950/CRID3 inhibition. Collectively, this work suggests that MCC950/CRID3-based therapies may effectively treat inflammation driven by wildtype NLRP3, but not CAPS-associated mutants.

immunology↗