A Computational Investigation of In Vivo Cytosolic Protein Delivery for Cancer Therapy

Abstract

The ability to specifically block or degrade cytosolic targets using therapeutic proteins would bring tremendous therapeutic opportunities in cancer therapy. Over the last few years, significant progress has been made with respect to tissue targeting, cytosolic delivery, and catalytic inactivation of targets, placing this aim within reach. Here, we developed a mathematical model specifically built for the evaluation of approaches towards cytosolic protein delivery, involving all steps from systemic administration to translocation into the cytosol and target engagement. Focusing on solid cancer tissues, we utilized the model to investigate the effects of microvascular permeability, receptor affinity, the cellular density of targeted receptors, as well as the mode of activity (blocking/degradation) on therapeutic potential. Our analyses provide guidance for the rational optimization of protein design for enhanced activity and highlight the importance of tuning the receptor affinity as a function of receptor density as well as the receptor internalization rate. Furthermore, we provide quantitative insights into how enzymatic cargoes can enhance the distribution, extent, and duration of therapeutic activity, already at very low catalytic rates. Our results illustrate that with current protein engineering approaches, the goal of delivery of cytosolic delivery of proteins for therapeutic effects is well within reach.

Mimicking the Biology of Engineered Protein and mRNA Nanoparticle Delivery Using a Versatile Microfluidic Platform

“…In our research, we have recently implemented organ-on-a-chip technology for the investigation of drug delivery in various contexts and reported novel insights for retargeted adenoviral vectors and therapeutic proteins targeting various cell surface receptors overexpressed on tumor tissue [8,9]. Notably, we were able to link experimental observations to predictions made by mathematical modeling of drug delivery, ultimately guiding a rational design of protein therapies [10].…”

A Hybrid In Silico and Tumor-on-a-Chip Approach to Model Targeted Protein Behavior in 3D Microenvironments

“…To evaluate the potential of mathematical modeling to predict DARPin diffusion in multicellular tumor spheroids (MCTS), we simulated DARPin delivery using a mathematical model similar to the one reported by Torres et al for the investigation of in vivo protein delivery [ 28 ]. MCTS are a reliable 3D in vitro model for simulating the features of avascular tumors, including a binding-site barrier, because of a high receptor density.…”

“…Our modeling approach is more similar to the approaches followed previously by Thurber and Wittrup, who performed a spatiotemporal investigation of the tumor delivery and binding-site barrier of targeted proteins in vitro [ 14 ], and Torres et.al, who performed a theoretical investigation of in vivo protein delivery [ 28 ].…”

“…A schematic of the input variables related to the therapy and the tissue, as well as the modelled outcomes, is given in Figure S4 . The underlying coupled equations were initially reported by Thurber et al [ 14 ] and Torres et al [ 28 ], and describe the kinetics of unbound DARPin (1), receptor (2), and DARPin–receptor complex (3), respectively. …”

“…Therefore, these models have the potential for a more in-depth investigation of the transport processes of drugs, including therapeutic proteins, into and around tumor tissues, and allow for a quick evaluation of novel formats with respect to their transport behavior. Importantly, the highly controlled nature of experiments with microfluidic models facilitates the application of modeling approaches for the description of transport processes, which, so far, have been limited to the description of processes in either static spheroids [ 14 ] or in vivo models [ 24 , 25 , 26 , 27 , 28 ].…”