A photoactivable multi-inhibitor nanoliposome for tumour control and simultaneous inhibition of treatment escape pathways

Nanoscale drug delivery vehicles can facilitate multimodal therapies of cancer by promoting tumour-selective drug release. However, few are effective because cancer cells develop ways to resist and evade treatment. Here, we introduce a photoactivable multi-inhibitor nanoliposome (PMIL) that imparts light-induced cytotoxicity in synchrony with a photoinitiated and sustained release of inhibitors that suppress tumour regrowth and treatment escape signalling pathways. The PMIL consists of a nanoliposome doped with a photoactivable chromophore (benzoporphyrin derivative, BPD) in the lipid bilayer, and a nanoparticle containing cabozantinib (XL184)--a multikinase inhibitor--encapsulated inside. Near-infrared tumour irradiation, following intravenous PMIL administration, triggers photodynamic damage of tumour cells and microvessels, and simultaneously initiates release of XL184 inside the tumour. A single PMIL treatment achieves prolonged tumour reduction in two mouse models and suppresses metastatic escape in an orthotopic pancreatic tumour model. The PMIL offers new prospects for cancer therapy by enabling spatiotemporal control of drug release while reducing systemic drug exposure and associated toxicities.

Efficient measurement of total tumor microvascularity ex vivo using a mathematical model to optimize volume subsampling

We introduce immunofluorescence and automated image processing protocols for serial tumor sections to objectively and efficiently quantify tumor microvasculature following antivascular therapy. To determine the trade-off between tumor subsampling and throughput versus microvessel quantification accuracy, we provide a mathematical model that accounts for tumor-specific vascular heterogeneity. This mathematical model can be applied broadly to define tumor volume samplings needed to reach statistical significance, depending on the biomarker in question and the number of subjects. Here, we demonstrate these concepts for tumor microvessel density and total microvascularity (TMV) quantification in whole pancreatic ductal adenocarcinoma tumors ex vivo. The results suggest that TMV is a more sensitive biomarker for detecting reductions in tumor vasculature following antivascular treatment. TMV imaging is a broadly accessible technique that offers robust assessment of antivascular therapies, and it offers promise as a tool for developing high-throughput assays to quantify treatment-induced microvascular alterations for therapeutic screening and development.

Cytotoxicity of cyclometallated ruthenium complexes: the role of ligand exchange on the activity

The cyclometallated Ru(II) complexes cis-[Ru(phpy)(phen)(CH3CN)2](PF6) (1; phpy(-)=deprotonated 2-phenylpyridine, phen=1,10-phenanthroline) and cis-[Ru(phpy)(bpy)(CH3CN)2](PF6) (2; bpy=2,2'-bipyridine) were investigated as potential agents for photodynamic therapy. The presence of phpy(-) in the coordination sphere results in a red-shift of the Ru→phen and Ru→bpy metal-to-ligand charge transfer of 1 and 2, respectively, thus improving the tissue penetration of light while maintaining the efficient photo-induced ligand exchange required for DNA binding. The 14-fold enhancement of OVCAR-5 cell death that occurs upon irradiation with 690 nm light can be attributed to photo-aquation. The role of glutathione (GSH) on the toxicity of the complex was also explored. Complexes 1 and 2 undergo ligand substitution in the presence of GSH in the dark, such that the metal may covalently bind to biomolecules. The combination of photo-induced ligand exchange and GSH-facilitated ligand exchange may explain the observed cytotoxicity.

Photoinduced ligand exchange and DNA binding of cis-[Ru(phpy)(phen)(CH3CN)2]+ with long wavelength visible light

The complex cis-[Ru(phpy)(phen)(CH3CN)2](+) (phpy=2-phenylpyridine, phen=1,10-phenanthroline) was investigated as a potential photodynamic therapy (PDT) agent. This complex presents desirable photochemical characteristics including a low energy absorption tail extending into the PDT window (600-850nm) and photoinduced exchange of the CH3CN ligands, generating a species analogous to the chemotherapy drug cisplatin. Furthermore, photochemical reactivity can be controlled through selective irradiation into the Ru-phen singlet metal-to-ligand charge transfer ((1)MLCT) band (λirr=500 nm) of [Ru(phpy)(phen)(CH3CN)2](+) in the presence of excess t-butylammonium chloride (TBACl) resulting in efficient photoinduced production of [Ru(phpy)(phen)(CH3CN)Cl] (Φ=0.25). This lower energy irradiation resulted in greater quantum yield of photosubstitution when compared to direct irradiation into the Ru-phpy (1)MLCT peak (λirr=450 nm; Φ=0.08) in CH2Cl2. It was found that the lower quantum yield observed for irradiation into the Ru→phpy(-)(1)MLCT band results from significant orbital mixing of the phpy(-) ligand with the t2g-type filled set in the metal, giving this state significant ligand-centered character. Lastly, this complex produced a decrease in the mobility of linearized ds-DNA when irradiated with λirr≥420nm, indicative of covalent binding by the transition metal complex similar to that observed for cisplatin. No change in mobility was found for the same samples kept in the dark indicating, unlike cisplatin, DNA binding of cis-[Ru(phpy)(phen)(CH3CN)2](+) only occurs with the activation of light. These observations support the use of cis-[Ru(phpy)(phen)(CH3CN)2](+) as a potential PDT agent by the photoinduced generation of a cisplatin analog.

Electronic tuning of ruthenium complexes by 8-quinolate ligands

A series of Ru(II) complexes were synthesized with the deprotonated forms of the ligands 8-hydroxyquinoline (quo(-)) and 5-NO(2)-8-hydroxyquinoline (5-NO(2)-quo(-)) as analogs to the prototypical complex [Ru(bpy)(3)](2+) (bpy = 2,2'-bipyridine). Electrochemistry, spectroscopy and density functional theory calculations were utilized to investigate the electronic tuning of the occupied t(2g)-type orbitals of the metal center with variation in the ligation sphere. The maximum of the lowest energy absorption of complexes containing one, two and three 8-quinolate ligands progressively redshifts from 452 nm in [Ru(bpy)(3)](2+) to 510 nm in [Ru(bpy)(2)(quo)](+), 515 nm in [Ru(bpy)(quo)(2)] and 540 nm in [Ru(quo)(3)](-) in water. This bathochromic shift results from the increase in energy of the occupied t(2g)-type orbital across the series afforded by coordination of each subsequent quo(-) ligand to the Ru(II) center. Time-dependent density functional theory calculations along with electrochemical analysis reveals that the lowest energy transition has contributions in the highest occupied molecular orbital from both the quo(-) ligand and the metal, such that the lowest energy transition is not from an orbital that is purely metal-centered in character as in [Ru(bpy)(3)](2+).

A general synthesis of tris-indole derivatives as potential iron chelators

The development of a novel route for the synthesis of a new class of compounds is described. The first tripodal, tris-indole amines are prepared by straightforward routes.