Emerging non-antibody‒drug conjugates (non-ADCs) therapeutics of toxins for cancer treatment.

The non-selective cytotoxicity of toxins limits the clinical relevance of the toxins. In recent years, toxins have been widely used as warheads for antibody‒drug conjugates (ADCs) due to their efficient killing activity against various cancer cells. Although ADCs confer certain targeting properties to the toxins, low drug loading capacity, possible immunogenicity, and other drawbacks also limit the potential application of ADCs. Recently, non-ADC delivery strategies for toxins have been extensively investigated. To further understand the application of toxins in anti-tumor, this paper provided an overview of prodrugs, nanodrug delivery systems, and biomimetic drug delivery systems. In addition, toxins and their combination strategies with other therapies were discussed. Finally, the prospect and challenge of toxins in cancer treatment were also summarized.

Inhibition of alanine-serine-cysteine transporter 2-mediated auto-enhanced photodynamic cancer therapy of co-nanoassembly between V-9302 and photosensitizer.

The efficiency of reactive oxygen species (ROS)-based photodynamic therapy (PDT) is far from satisfactory, because cancer cells can adapt to PDT by upregulating glutathione (GSH) levels. The GSH levels in tumor cells are determined based on glutamine availability via alanine-serine-cysteine transporter 2 (ASCT2)-mediated entry into cells. Herein, we develop co-assembled nanoparticles (PPa/V-9302 NPs) of the photosensitizer pyropheophorbide a (PPa) and V-9302 (a known inhibitor of ASCT2) in a 1:1 M ratio using a one-step precipitation method to auto-enhance photodynamic therapy. The computational simulations revealed that PPa and V-9302 could self-assemble through different driving forces, such as π-π stacking, hydrophobic interactions, and ionic bonds. Such PPa/V-9302 NPs could disrupt the intracellular redox homeostasis due to enhanced ROS production via PPa-induced PDT and reduced GSH synthesis via inhibition of the ASCT2-mediated glutamine flux by V-9302. The in vivo assays reveal that PPa/V-9302 NPs could increase the drug accumulation in tumor sites and suppress tumor growth in BALB/c mice bearing mouse breast carcinoma (4 T1) tumor. Our findings provide a new paradigm for the rational design of the PDT-based combinational cancer therapy.