Polymer Cancerostatics Targeted with an Antibody Fragment Bound via a Coiled Coil Motif: In Vivo Therapeutic Efficacy against Murine BCL1 Leukemia

Abstract

A BCL1 leukemia‐cell‐targeted polymer–drug conjugate with a narrow molecular weight distribution consisting of an N‐(2‐hydroxypropyl)methacrylamide copolymer carrier and the anticancer drug pirarubicin is prepared by controlled radical copolymerization followed by metal‐free click chemistry. A targeting recombinant single chain antibody fragment (scFv) derived from a B1 monoclonal antibody is attached noncovalently to the polymer carrier via a coiled coil interaction between two complementary peptides. Two pairs of coiled coil forming peptides (abbreviated KEK/EKE and KSK/ESE) are used as linkers between the polymer–pirarubicin conjugate and the targeting protein. The targeted polymer conjugate with the coiled coil linker KSK/ESE exhibits 4× better cell binding activity and 2× higher cytotoxicity in vitro compared with the other conjugate. Treatment of mice with established BCL1 leukemia using the scFv‐targeted polymer conjugate leads to a markedly prolonged survival time of the experimental animals compared with the treatment using the free drug and the nontargeted polymer–pirarubicin conjugate.

Polymer Cancerostatics Containing Cell-Penetrating Peptides: Internalization Efficacy Depends on Peptide Type and Spacer Length

“…The IC 50 of free pirarubicin was one order of magnitude lower. This observation is typical when comparing cytotoxicity of free and polymer bound drug [23,28,29]. The positive effect of CPP is more pronounced after relatively short incubation time (24 h) with the cells due to the faster internalization of CPP-polymer conjugates compared with the peptide-free conjugates.…”

Polymer Therapeutics: Biomarkers and New Approaches for Personalized Cancer Treatment

“…The next hurdle faced by a given PT is the voyage through the bloodstream to the tumor and then passage from the bloodstream into the tumor site (we note that we concentrate here on the application of PTs to solid tumors, even given reports of efficient PT-based therapies for leukemia [ 76 , 77 ]). Tumor targeting strategies for PTs include the tumor specific uptake of PTs of a certain size by the enhanced permeability and retention (EPR) effect (“passive” targeting) [ 78 , 79 ] or the addition of specific ligands or molecules to the PT to target them to specific tumor-targets (“active” targeting) [ 80 ].…”

Fluorescence Imaging as a Tool in Preclinical Evaluation of Polymer-Based Nano-DDS Systems Intended for Cancer Treatment

“…Within the FI experiment, one can utilize sophisticated fluorescent probes that are tailored as targets for a specific receptor or enzyme. These probes are essentially fluorochromes that are bound to a ligand that is specific for a certain target, such as a monoclonal antibody [46,47], antibody fragment [48,49], peptide [50,51] or aptamer [52]. The probes can be permanently active or activatable by changes in conformation or chemical structure.…”

“…At the cellular level, the nano-device size, shape, and charge, and even the flexibility [60,61,62] and morphology [63,64], determine the rate of internalization, the intracellular localization, the anticancer drug release profile, and the degradation of DDS. The efficacy of active targeting using monoclonal antibodies, their fragments, selected oligopeptides or saccharides could be readily evaluated to confirm the primary concept and design of targeted DDS [49,65,66]. Moreover, most DDS based on polymer carriers, micelles, nanoparticles, or liposomes can be easily labeled by different fluorochromes; thus, various biological characteristics and processes can be studied in detail by fluorescence microscopy [31,67,68].…”