UCSF

Prostate-specific membrane antigen (PSMA) is a cell surface enzyme highly over expressed in prostate cancer cells that can be employed as a target for prostate cancer imaging and drug delivery. Boron Neutron Capture Therapy (BNCT) is an emerging noninvasive therapeutic modality for treating locally invasive malignant tumors by selective delivery of high boron content to the tumour and then subjecting the tumour to epithermal neutron beam radiation. In this study, we develop carborane encapsulated amphiphilic polymer nanoparticles by conjugating urea based PSMA inhibitors (ACUPA) and 89Zr chelating deferoxamine B (DFB) ligand and have investigated their efficacy to deliver enhanced boron payload to PSMA positive prostate cancer cells with simultaneous positron emission tomography (PET) imaging . Three different carborane encapsulated PLGA-b-PEG nanoparticles (NPs) were formulated with and without the PSMA targeting ligand, out of which two selected formulations; DFB(25)ACUPA(75) NPs and DFB(25) NPs radiolabelled with 89Zr were administered to mice bearing dual PSMA(+) PC3-Pip and PSMA(-) PC3-Flu xenografts. PET imaging and biodistribution studies were performed to demonstrate the in vivo uptake in mice. The NPs showed 2-fold higher uptake in PSMA(+) PC3-Pip tumors to that of PSMA(-) PC3-Flu tumors with a very high tumor/blood ratio of 20. However, no significant influence of the ACUPA ligands were observed. Additionally, the NPs demonstrated fast release of carborane with low delivery of boron to tumors in vivo. Although the in vivo afficacy of those NPs remain limited, a significant progress towards the synthesis, characterization and initial biological evaluation of the polymer nanoparticles is proposed in this report and the results presented could guide the future design of amphiphilic polymer NPs for theranostic applications.