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Combinations of conventional chemotherapeutics with unconventional anticancer agents such as reactive oxygen and nitrogen species may offer treatment benefits for cancer therapies. Here we report a novel polymeric platform combining the delivery of Doxorubicin (DOXO) with the light-regulated release of nitric oxide (NO). An amphiphilic block-copolymer (P1) was designed and synthesized as the drug carrier, with pendant amine groups to attach DOXO via a urea linkage and a NO photodonor (NOPD) activable by visible light. The two grafted-copolymers (P1-DOXO and P1-NOPD) self-assembled via solvent displacement methods into nanoparticles (NPs), containing both therapeutic components (NP1) and, for comparison, the individual NOPD (NP2) and DOXO (NP3). All the NPs were fully characterized in terms of physicochemical, photochemical and photophysical properties. These experiments demonstrated that integration of the NOPD within the polymeric scaffold enhanced the NO photoreleasing efficiency when compared with the free NOPD, and that the proximity to DOXO on the polymer chains did not significantly affect the enhanced photochemical performance. Internalization of the NPs into lung, intestine, and skin cancer cell lines was investigated after co-formulation with Cy5 fluorescent tagged polymers, and cytotoxicity of the NPs against the same panel of cell lines was assessed under dark and light conditions. The overall results demonstrate effective cell internalization of the NPs and a notable enhancement in killing activity of the dual-action therapeutic NP1 when compared with NP2, NP3 and the free DOXO, respectively. This suggests that the combination of DOXO with photoregulated NO release, achieved through the mixed formulation strategy of tailored polymer conjugate NPs, may open new treatment modalities based on the use of NO to improve cancer therapies.

Glioblastoma (GBM) is the most common, malignant and aggressive brain tumour in adults. Despite the use of multimodal treatments, involving surgery, followed by concomitant radiotherapy and chemotherapy, the median survival for patients remains less than 15 months from diagnosis. Low penetration of drugs across the blood-brain barrier (BBB) is a dose-limiting factor for systemic GBM therapies, and as a result, post-surgical intracranial drug delivery strategies are being developed to ensure local delivery of drugs within the brain. Here we describe the effects of PEGylated poly(lactide)-poly(carbonate)-doxorubicin (DOX) nanoparticles (NPs) on the metabolic activity of primary cancer cell lines derived from adult patients following neurosurgical resection, and the commercially available GBM cell line, U87. The results showed that non-drug-loaded NPs were well tolerated at concentrations of up to 100 µg/mL while tumour cell-killing effects were observed for the DOX-NPs at the same concentrations. Further experiments evaluated the release of DOX from polymer-DOX conjugate NPs when incorporated in a thermosensitive in situ gelling poly(DL-lactic-co-glycolic acid) and poly(ethylene glycol) (PLGA/PEG) matrix paste, in order to simulate the clinical setting of a locally injected formulation for GBM following surgical tumour resection. These assays demonstrated drug release from the polymer pro-drugs, when in PLGA/PEG matrices of two formulations, over clinically relevant time scales. These findings encourage future in vivo assessment of the potential capability of polymer–drug conjugate NPs to penetrate brain parenchyma efficaciously, when released from existing interstitial delivery systems. [ABSTRACT FROM AUTHOR]