Polymer Pro-Drug Nanoparticles for Sustained Release of Cytotoxic Drugs Evaluated in Patient-Derived Glioblastoma Cell Lines and In Situ Gelling Formulations

Abstract

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.

Metabolic modeling-based drug repurposing in Glioblastoma

“…Two of the genes pinpointed for the low survival models agreed with our results: ACOT8 (acyl-CoA thioesterase 8) and GPAT4 (glycerol-3-phosphate acyltransferase 4), both related to lipid metabolism. The former is targeted by three drugs with antineoplastic activity which decrease its expression: doxorubicin 52 , 59 , orlistat 60 , 61 , and paclitaxel 60 , 62 . GPAT4 is the only gene of the GPAT family expressed in the brain, and it has recently been identified as a potential drug target for treating obesity-associated depression 63 .…”

“…G lioblastoma IN vasive margin (GIN28, GIN31) and G lioblastoma C ontrast- E nhanced core (GCE28, GCE31) cell lines have been previously derived at Queen’s Medical Centre, Nottingham, authenticated using short tandem repeat genotyping (Supplementary Table S1 ) and used at passages 21–29, 27–36, 15–23 and 28–37, respectively 51 , 52 . Cell lines were cultured using adherent T75 flasks (Corning) in Dulbecco’s Modified Eagle Medium (Gibco) supplemented with 10% FBS (Sigma-Aldrich) and incubated under humidified growth conditions at 37 °C and 5% CO 2 .…”

DDRugging glioblastoma: understanding and targeting the DNA damage response to improve future therapies

“…In addition to the aforementioned needed improvement in preclinical models that better reflect postsurgical residual disease, an important factor alongside the development of such multimodal strategies will be further improvements in the efficient delivery of therapeutically active doses of drugs beyond the BBB, which remains a significant challenge in glioblastoma therapy [ 3 ]. Potential innovations on the horizon include the use of MRI‐directed magnetic nanoparticles [ 217 , 218 ], surgical delivery of in situ gelling agents [ 219 , 220 ] and enhanced intrathecal/cerebrospinal fluid delivery using novel viral vectors, antibody ligands or exosomes [ 221 , 222 , 223 ]. Such approaches, in addition to traditional oral or intravenous delivery approaches, coupled with novel ways to disrupt the BBB, such as ultrasound [ 224 , 225 ] or TTFields [ 226 ]‐based approaches, will hopefully provide the best chance for DDR‐targeting approaches to provide much‐needed clinical benefit to patients and families faced with the devastating diagnosis of a high‐grade glioma.…”

Targeting Systems to the Brain Obtained by Merging Prodrugs, Nanoparticles, and Nasal Administration

“…Very recently, PEGylated poly(lactide)-poly(carbonate)-doxorubicin nanoparticles (DOX-NPs) have been synthetized, exploiting a carbamate moiety on the sidechain of the monomer unit to conjugate the drug, which can be successively released by the action of ureases. Their efficient cytotoxic activity on both primary cancer cell lines derived from adult patients following neurosurgical resection, and the commercially available GBM cell line, U87, has been demonstrated [ 122 ]. Interestingly, DOX-NPs have further been incorporated in various poly( dl -lactic- co -glycolic acid) and poly(ethylene glycol) (PLGA/PEG) matrixes.…”

“…When mixed with saline solutions at room temperature, these microparticles form a paste, enabling the surgeon to line the resection cavity site following removal of the tumor. In this case, the aim is not to obtain a system able to cross the BBB, but, instead, to obtain a depot formulation able to release the DOX-NPs, exploiting their ability to selectively deliver the drug into the tumor cells, avoiding both the entry of the drug into healthy cells, and off-target side effects [ 122 ].…”