ABSTRACT
Epidermal growth factor receptor (EGFR) is highly expressed in 80-90% of head and neck squamous cell carcinomas (HNSCCs), making it an ideal target for antibody-drug conjugates. Depatuxizumab mafodotin (ABT-414), is an EGFR-targeting ADC comprised of the monoclonal antibody ABT-806 conjugated to monomethyl auristatin F, a tubulin polymerization inhibitor. This study assessed the in vivo efficacy of ABT-414 in HNSCC. The effects of ABT-414 on HNSCCs were determined using in vitro cytotoxicity assays and in vivo flank xenograft mouse models. The distribution of ABT-414 was assessed ex vivo via optical imaging methods using a conjugate of ABT-414 to the near-infrared agent IRDye800. In vitro treatment of high EGFR-expressing human HNSCC cell lines (UMSCC47 and FaDu) with ABT-414 (0-3.38 nM) resulted in dose-dependent cell death (IC50 values of 0.213 nM and 0.167 nM, respectively). ABT-414 treatment of the FaDu mouse xenografts displayed antitumor activity (Pâ =â 0.023) without a change in body mass (Pâ =â 0.1335), whereas treatment of UMSCC47 did not generate a significant response (Pâ =â 0.1761). Fluorescence imaging revealed ABT-414-IRDye800 accumulation in the tumors of both FaDu and UMSCC47 cell lines, with a signal-to-background ratio of >10. ABT-414 treatment yielded antitumor activity in FaDu tumors, but not in UMSCC47, highlighting the potential for ABT-414 efficacy in high EGFR-expressing tumors. Although ABT-414-IRDye800 localized tumors in both cell lines, the differing antitumor responses highlight the need for further investigation into the role of the tumor microenvironment in drug delivery.
Subject(s)
Antibodies, Monoclonal, Humanized , ErbB Receptors , Head and Neck Neoplasms , Xenograft Model Antitumor Assays , Animals , Humans , Mice , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/pathology , Head and Neck Neoplasms/metabolism , Antibodies, Monoclonal, Humanized/pharmacology , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/metabolism , Cell Line, Tumor , Squamous Cell Carcinoma of Head and Neck/drug therapy , Squamous Cell Carcinoma of Head and Neck/pathology , Female , Mice, Nude , Cell Proliferation/drug effects , ImmunoconjugatesABSTRACT
Twenty novel Mn, Fe, and Cu complexes of ethylene cross-bridged tetraazamacrocycles with potentially copolymerizable allyl and benzyl pendant arms were synthesized and characterized. Multiple X-ray crystal structures demonstrate the cis-folded pseudo-octahedral geometry forced by the rigidifying ethylene cross-bridge and show that two cis coordination cites are available for interaction with substrate and oxidant. The Cu complexes were used to determine kinetic stability under harsh acidic and high-temperature conditions, which revealed that the cyclam-based ligands provide superior stabilization with half-lives of many minutes or even hours in 5 M HCl at 50-90 °C. Cyclic voltammetry studies of the Fe and Mn complexes reveal reversible redox processes indicating stabilization of Fe2+/Fe3+ and Mn2+/Mn3+/Mn4+ oxidation states, indicating the likelihood of catalytic oxidation for these complexes. Finally, dye-bleaching experiments with methylene blue, methyl orange, and rhodamine B demonstrate efficient catalytic decolorization and allow selection of the most successful monomeric catalysts for copolymerization to produce future heterogeneous water purification materials.
