Modular Nanoparticulate Prodrug Design Enables Efficient Treatment of Solid Tumors Using Bioorthogonal Activation

Abstract

Prodrug strategies that facilitate localized and controlled activity of small-molecule therapeutics can reduce systemic exposure and improve pharmacokinetics, yet limitations in activation chemistry have made it difficult to assign tunable multifunctionality to prodrugs. Here, we present the design and application of a modular small-molecule caging strategy that couples bioorthogonal cleavage with a self-immolative linker and an aliphatic anchor. This strategy leverages recently discovered in vivo catalysis by a nanoencapsulated palladium compound (Pd-NP), which mediates alloxylcarbamate cleavage and triggers release of the activated drug. The aliphatic anchor enables >90% nanoencapsulation efficiency of the prodrug, while also allowing >104-fold increased cytotoxicity upon prodrug activation. We apply the strategy to a prodrug formulation of monomethyl auristatin E (MMAE), demonstrating its ability to target microtubules and kill cancer cells only after selective activation by Pd-NP. Computational pharmacokinetic modeling provides a mechanistic basis for the observation that the nanotherapeutic prodrug strategy can lead to more selective activation in the tumor, yet in a manner that is more sensitive to variable enhanced permeability and retention (EPR) effects. Combination treatment with the nanoencapsulated MMAE prodrug and Pd-NP safely blocks tumor growth, especially when combined with a local radiation therapy regimen that is known to improve EPR effects, and represents a conceptual step forward in prodrug design.

Single‐Cell Intravital Microscopy of Trastuzumab Quantifies Heterogeneous in vivo Kinetics

“…This study presents an IVM‐based approach to simultaneously track (1) the pharmacokinetics and selective association of mAb with its putative targets in tumors, (2) heterogeneous target expression on cancer cells, and (3) infiltrating immune populations, all at the single‐cell level. This work builds on the growing development of IVM as a tool for studying drug pharmacology in cancer, and previous reports have used IVM to examine the behavior of cytotoxic chemotherapies , targeted kinase and poly‐ADP ribose polymerase inhibitors, nanoparticle‐encapsulated therapeutics , and anti‐PD1 immune checkpoint blockade mAb therapy . In several cases, mosaic xenograft models have been successfully used to test the impact of a particular protein on drug pharmacology, while holding other features of the TME relatively constant.…”

Understanding the In Vivo Fate of Advanced Materials by Imaging

“…IVM visualized that sequentially administered PLGA-PEG NPs carrying palladium compounds and model pro-drugs accumulated and locally activated within the tumor microenvironment, while minimizing activation at potential sites of toxicity. [210,211] Similarly, other studies have shown that implanted Pd-conjugated resin microparticles induce site-specific catalysis of model pro-drugs [57] (Figure 8). For imaging, caged fluorophores are typically used as model "pro-drugs" that become fluorescent upon palladium-triggered Figure 7.…”

In vivo microscopy reveals macrophage polarization locally promotes coherent microtubule dynamics in migrating cancer cells

“…Fluorescent fusion proteins of EB3, also known as MT-associated protein RP/ EB family member 3 (MAPRE3), are widely used tools to visualize MT dynamics in live cells 18 . They are relatively non-perturbing of endogenous dynamics and report activity of MT-targeting drugs in cancer 19,20 . As a model system, we used HT1080 human fibrosarcoma cells, since they have been characterized, including by intravital microscopy (IVM), for their migratory behavior, responsiveness to MT-targeting therapies, and distinct cytoskeletal characteristics in 2D vs. 3D tissue cultures [19][20][21][22][23][24] .…”