An Engineered Prussian Blue Nanoparticles‐Based Nanoimmunotherapy Elicits Robust and Persistent Immunological Memory in a TH‐MYCN Neuroblastoma Model

Abstract

A combination therapy using Prussian blue nanoparticles (PBNP) as photothermal therapy (PTT) agents coated with CpG oligodeoxynucleotides, an immunologic adjuvant, as a nanoimmunotherapy (CpG‐PBNP‐PTT) for neuroblastoma (NB) is described. NB driven by MYCN amplification confers high risk and correlates with a dismal prognosis, accounting for the majority of NB‐related mortality. The efficacy of the CpG‐PBNP‐PTT nanoimmunotherapy in a clinically relevant, TH‐MYCN murine NB model (9464D) overexpressing MYCN is tested. When administered to 9464D NB cells in vitro, CpG‐PBNP‐PTT triggers thermal dose‐dependent immunogenic cell death and tumor cell priming for immune recognition in vitro, measured by the expression of specific costimulatory and antigen‐presenting molecules. In vivo, intratumorally administered CpG‐PBNP‐PTT generates complete tumor regression and significantly higher long‐term survival compared to controls. Furthermore, CpG‐PBNP‐PTT‐treated mice reject tumor rechallenge. Ex vivo studies confirm these therapeutic responses result from the generation of robust T cell‐mediated immunological memory. Consequently, in a synchronous 9464D tumor model, CpG‐PBNP‐PTT induces complete tumor regression on the treated flank and significantly slows tumor progression on the untreated flank, improving animal survival. These findings demonstrate that localized administration of the CpG‐PBNP‐PTT nanoimmunotherapy drives potent systemic T cell responses in solid tumors such as NB and therefore has therapeutic implications for NB.

Anti-Fn14-Conjugated Prussian Blue Nanoparticles as a Targeted Photothermal Therapy Agent for Glioblastoma

“…PTT using aFn14-PBNP elicited thermally induced cell death in both GBM tumor lines as evidenced by a decrease in cellular viability in a laser power-dependent manner ( Figure 3 A). For U87 cells, the cellular viability decreased from 97.85% for aFn14-PBNP (without the laser) to 42.95% at 0.75 W, with the lowest viability of 18.45% observed at the highest laser power of 2 W. Similarly, for U251 cells, the cellular viability decreased from 95.00% for aFn14-PBNP (without the laser) to 55.25% at 0.75 W, with the lowest viability of 11.19% observed at the highest laser power of 2 W. For both tumor lines, the IC50 was attained at thermal doses of 4.72 for U87 and 4.86 for U251, respectively corresponding to a laser power of 0.75 W. These findings with aFn14-PBNP-based PTT in GBM tumor cells are consistent with our observations when using PBNPs for PTT in diverse tumor cell lines such as neuroblastoma, melanoma, and breast cancer [ 9 , 10 , 42 , 43 ]. We did not conduct studies assessing the effects of PBNPs alone (without the laser) as we have extensively observed that the PBNPs have a negligible effect on tumor cellular viability at the concentrations used for this study [ 9 , 10 , 42 ].…”

“…ICD can convert an immunologically “cold” tumor to a “hot” one, where released antigens can activate an immune response against the tumor. Our group and others have previously shown that PBNP-mediated PTT can induce ICD in pediatric neuroblastoma [ 9 , 10 , 41 , 42 ], melanoma [ 43 ], and triple-negative breast adenocarcinoma preclinical models, to name a few, and is being investigated in this study as a novel treatment option for GBM. ICD is not always induced by nanoparticle-mediated PTT, but the consistency with which our lab has observed PBNP-PTT-induced ICD makes PBNPs an attractive material.…”

A Mini-Review of Diagnostic and Therapeutic Nano-Tools for Pancreatitis

“…Meanwhile, PB NPs can simulate a variety of antioxidant enzyme activities, which has attracted great attention in the treatment of inflammatory diseases in recent years. [71][72][73][74][75] As shown in Figure 4, Zheng et al developed a PB NPs (PBzyme) that can act as a nano-enzyme to remove a variety of ROS and pro-inflammatory factors including •OH, •OOH, and H 2 O 2 . It reduces necrosis, nucleic acid damage, and peroxidation by downregulating TLR-related NF-κB signaling pathway Similarly, the rare earth element nanoparticles also have ROS scavenging properties.…”

Nanotechnology-Based Diagnostic and Therapeutic Strategies for Neuroblastoma

“…Juliana et al demonstrated that combination of PTT with nanomaterials containing immune adjuvant and CTLA-4 monoclonal antibody improved T-cell levels and inhibited tumor growth in NB mice, while exerting a memory effect to suppress tumor recurrence, with superior therapeutic efficacy than CTLA-4 monoclonal antibody or PTT therapy alone ( Cano-Mejia et al, 2017 ). They showed in their mouse model of TH-MYCN gene-driven malignant NB that PTT therapy with PBNP coated with the immune adjuvant CpG oligonucleotide (CpG-PBNP-PTT) was effective in regressing mouse tumors, improving survival time and activating t cell-mediated systemic immune responses ( Figure 6A ) ( Shukla et al, 2021 ). Similarly, combining CpG-PBNP with anti-CTLA-4 immunotherapy can not only cause ablative cell death, but also alter the surface levels of co-stimulatory, antigen-presenting, and co-inhibitory molecules on NB cells ( Cano-Mejia et al, 2020 ).…”

“…(A) Schematic of the mechanism of action of the CpG-PBNP-PTT-based nanoimmunotherapy in the TH-MYCN model of NB. Reproduced with permission from ( Shukla et al, 2021 ). Copyright 2021, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.…”