Cathepsin B-Cleavable Cyclopeptidic Chemotherapeutic Prodrugs

Abstract

Cyclopeptidic chemotherapeutic prodrugs (cPCPs) are macromolecular protease-sensitive doxorubicin (DOX) prodrugs synthesized from a cyclodecapeptidic scaffold, termed Regioselectively Addressable Functionalized Template (RAFT). In order to increase the chemotherapeutic potential of DOX and limit its toxicity, we used a Cathepsin B (Cat B)-sensitive prodrug concept for its targeted release since this enzyme is frequently overexpressed in cancer cells. Copper-free “click” chemistry was used to synthesize cPCPs containing up to four DOX moieties tethered to the upper face of the scaffold through a Cat B-cleavable peptidic linker (GAGRRAAG). On the lower part, PEG 5, 10 and 20 kDa and a fifth peptidyl DOX moiety were grafted in order to improve the solubility, bioavailability and pharmacokinetic profiles of the compound. In vitro results on HT1080 human fibrosarcoma cells showed that cPCPs display a delayed action that consists of a cell cycle arrest in the G2 phase comparable to DOX alone, and increased cell membrane permeability.

Double-PEGylated Cyclopeptidic Photosensitizer Prodrug Improves Drug Uptake from In Vitro to Hen’s Egg Chorioallantoic Membrane Model

“…2 ) was taken up by fibrosarcoma cells through late endosomes and lysosomes [33]. This supports the idea that PEG chains foster the bioavailability of the conjugate.…”

“…In our case, we used one or two bigger PEG side chain(s), hoping that the resulting small active fragments would be rapidly internalized and not flushed through the bloodstream. Nevertheless, in a similar work [33] whose construct was based on a cathepsin B-sensitive peptidic linker, activation by this lysosomal protease was observed in the late endosomes and lysosomes, demonstrating that the full construct could be internalized into cells prior to being cleaved. If one wants to cleave the PEG sidechain before internalizing the drug into the cells, the linker might also be designed to react to ROS produced by a photosensitizer such as Ce6.…”

Targeted Intracellular Delivery of Trastuzumab Using Designer Phage Lambda Nanoparticles Alters Cellular Programs in Human Breast Cancer Cells

“…Of note, the lambda PLP platform described here can be rapidly redesigned to include other or additional multimodality probes, biologics, and/or compounds. This includes replacing the fluorophore used with an IR dye more amenable to in vivo imaging and the addition of synthetic polymers to improve pharmacokinetic parameters, enzymatic inhibitors to inhibit specific protein–protein interactions, , and/or cytotoxic agents to enhance the therapeutic effect, as depicted in Figure A.…”

Cathepsin B-Cleavable Polymeric Photosensitizer Prodrug for Selective Photodynamic Therapy: In Vitro Studies

“…Two G residues (at the amino- and carboxyl-end) were added for further chemical modification. Previously, we have also shown the proteolytic cleavability of the GAGRRAAG peptide linker using CTSB from a human placenta [ 24 ]. CTSB-sensitive PPP contains multiple copies of Pha as the PS.…”

“…Photoexcitation of CTSB-PPP thus leads to exciplex formation and quenching via internal conversion. In the target tissue, after proteolytic cleavage of the peptide sequence, the inactive PS becomes active, increasing the distance between the Pha molecules, i.e., the “switch-on state” [ 10 , 21 , 22 , 23 , 24 ]. These active PS can fluoresce upon activation via light of an appropriate wavelength (~670 nm in case of Pha), in the presence of molecular oxygen, leading to the generation of reactive oxygen species (ROS) that locally destroys cells over short diffusion distances [ 25 ].…”