Nanoscale Coordination Polymers for Combined Chemotherapy and Photodynamic Therapy of Metastatic Cancer.

Combination therapy enhances anticancer efficacy through synergistic effects of different drugs/modalities and can potentially address the challenges in the treatment of metastatic diseases. Here we report the design of carb/pyro nanoscale coordination polymer nanoparticles that carry carboplatin (carb) in the core and the photosensitizer pyrolipid (pyro) on the shell for the treatment of metastatic triple negative breast cancer. Upon light irradiation, carb/pyro generated reactive oxygen species to cause severe cell apoptosis and early calreticulin exposure. Upon intravenous injection and local light irradiation, carb/pyro significantly regressed tumor growth in the 4T1 murine metastatic breast cancer model. When combined with an anti-CD47 antibody, carb/pyro with light irradiation completely eradicated primary and metastatic 4T1 tumors in 50% mice. The anticancer efficacy of carb/pyro was also demonstrated in the CT26 murine colorectal cancer model.

In Vivo Delivery and Therapeutic Effects of a MicroRNA on Colorectal Liver Metastases.

Multiple therapeutic agents are typically used in concert to effectively control metastatic tumors. Recently, we described microRNAs that are associated with the oligometastatic state, in which a limited number of metastatic tumors progress to more favorable outcomes. Here, we report the effective delivery of an oligometastatic microRNA (miR-655-3p) to colorectal liver metastases using nanoscale coordination polymers (NCPs). The NCPs demonstrated a targeted and prolonged distribution of microRNAs to metastatic liver tumors. Tumor-targeted microRNA miR-655-3p suppressed tumor growth when co-delivered with oxaliplatin, suggesting additive or synergistic interactions between microRNAs and platinum drugs. This is the first known example of systemically administered nanoparticles delivering an oligometastatic microRNA to advanced metastatic liver tumors and demonstrating tumor-suppressive effects. Our results suggest a potential therapeutic strategy for metastatic liver disease by the co-delivery of microRNAs and conventional cytotoxic agents using tumor-specific NCPs.

Nanoscale Coordination Polymers Codeliver Chemotherapeutics and siRNAs to Eradicate Tumors of Cisplatin-Resistant Ovarian Cancer.

Drug resistance impedes the successful treatment of many types of cancers, especially ovarian cancer (OCa). To counter this problem, we developed novel long-circulating, self-assembled core-shell nanoscale coordination polymer (NCP) nanoparticles that efficiently deliver multiple therapeutics with different mechanisms of action to enhance synergistic therapeutic effects. These NCP particles contain high payloads of chemotherapeutics cisplatin or cisplatin plus gemcitabine in the core and pooled siRNAs that target multidrug resistant (MDR) genes in the shell. The NCP particles possess efficient endosomal escape via a novel carbon dioxide release mechanism without compromising the neutral surface charge required for long blood circulation and effectively downregulate MDR gene expression in vivo to enhance chemotherapeutic efficacy by several orders of magnitude. Even at low doses, intraperitoneal injections of nanoparticles led to effective and long-lasting tumor regression/eradication in subcutaneous and intraperitoneal xenograft mouse models of cisplatin-resistant OCa. By silencing MDR genes in tumors, self-assembled core-shell nanoparticles promise a more effective chemotherapeutic treatment for many challenging cancers.

Chlorin-Based Nanoscale Metal-Organic Framework Systemically Rejects Colorectal Cancers via Synergistic Photodynamic Therapy and Checkpoint Blockade Immunotherapy.

Photodynamic therapy (PDT) can destroy local tumors and minimize normal tissue damage, but is ineffective at eliminating metastases. Checkpoint blockade immunotherapy has enjoyed recent success in the clinic, but only elicits limited rates of systemic antitumor response for most cancers due to insufficient activation of the host immune system. Here we describe a treatment strategy that combines PDT by a new chlorin-based nanoscale metal-organic framework (nMOF), TBC-Hf, and a small-molecule immunotherapy agent that inhibits indoleamine 2,3-dioxygenase (IDO), encapsulated in the nMOF channels to induce systemic antitumor immunity. The synergistic combination therapy achieved effective local and distant tumor rejection in colorectal cancer models. We detected increased T cell infiltration in the tumor microenvironment after activation of the immune system with the combination of IDO inhibition by the small-molecule immunotherapy agent and immunogenic cell death induced by PDT. We also elucidated the underlying immunological mechanisms and revealed compensatory roles of neutrophils and B cells in presenting tumor-associated antigens to T cells in this combination therapy. We believe that nMOF-enabled PDT has the potential to significantly enhance checkpoint blockade cancer immunotherapy, affording clinical benefits for the treatment of many difficult-to-treat cancers.

A Chlorin-Based Nanoscale Metal-Organic Framework for Photodynamic Therapy of Colon Cancers.

We report here the rational design of the first chlorin-based nanoscale metal-organic framework (NMOF), DBC-UiO, with much improved photophysical properties over the previously reported porphyrin-based NMOF, DBP-UiO. Reduction of the DBP ligands in DBP-UiO to the DBC ligands in DBC-UiO led to a 13 nm red shift and an 11-fold increase in the extinction coefficient of the lowest-energy Q band. While inheriting the crystallinity, stability, porosity, and nanoplate morphology of DBP-UiO, DBC-UiO sensitizes more efficient (1)O2 generation and exhibits significantly enhanced photodynamic therapy (PDT) efficacy on two colon cancer mouse models as a result of its improved photophysical properties. Both apoptosis and immunogenic cell death contributed to killing of cancer cells in DBC-UiO-induced PDT.

Enzymatic synthesis of periodic DNA nanoribbons for intracellular pH sensing and gene silencing.

We report the construction of periodic DNA nanoribbons (DNRs) by a modified DNA origami method. Unlike the conventional DNA origami, the DNR scaffold is a long, single-stranded DNA of tandem repeats, originating from the rolling circular amplification (RCA). Consequently, the number of folding staple strands tremendously decreases from hundreds to a few, which makes the DNR production scalable and cost-effective, thus potentially removing the barrier for practical applications of DNA nanostructures. Moreover, the co-replicational synthesis of scaffold and staple strands by RCA-based enzymatic reactions allows the generation of DNRs in one pot, further reducing the cost. Due to their unique periodicity, rigidity, and high aspect ratio, DNRs are efficiently internalized into cells and escape from endosomal entrapment, making them potential nanocarriers for imaging agents and biological therapeutics. We demonstrated proof-of-concept applications of DNRs as an intracellular pH sensor and an efficient small interfering RNA delivery vehicle in human cancer cells.

Hybrid nanoparticles for cancer imaging and therapy.

Hybrid nanoparticles, composed of both inorganic and organic components, have been exploited as promising platforms for cancer imaging and therapy. This class of nanoparticles can not only retain the beneficial features of both inorganic and organic materials, but also allow systematic fine-tuning of their properties through the judicious combination of functional components. This chapter summarizes recent advances in the design and synthesis of hybrid nanomaterials, with particular emphasis on two main categories of hybrid nanoparticles: Nanoscale metal-organic frameworks (also known as nanoscale coordination polymers) and polysilsesquioxane nanoparticles. Preliminary applications of these hybrid nanoparticles in cancer imaging and therapy are described.

Nanoscale metal-organic framework for highly effective photodynamic therapy of resistant head and neck cancer.

Photodynamic therapy (PDT) is an effective anticancer procedure that relies on tumor localization of a photosensitizer followed by light activation to generate cytotoxic reactive oxygen species (e.g., (1)O2). Here we report the rational design of a Hf-porphyrin nanoscale metal-organic framework, DBP-UiO, as an exceptionally effective photosensitizer for PDT of resistant head and neck cancer. DBP-UiO efficiently generates (1)O2 owing to site isolation of porphyrin ligands, enhanced intersystem crossing by heavy Hf centers, and facile (1)O2 diffusion through porous DBP-UiO nanoplates. Consequently, DBP-UiO displayed greatly enhanced PDT efficacy both in vitro and in vivo, leading to complete tumor eradication in half of the mice receiving a single DBP-UiO dose and a single light exposure. NMOFs thus represent a new class of highly potent PDT agents and hold great promise in treating resistant cancers in the clinic.

Nanoscale metal-organic frameworks for real-time intracellular pH sensing in live cells.

Real-time measurement of intracellular pH in live cells is of great importance for understanding physiological/pathological processes and developing intracellular drug delivery systems. We report here the first use of nanoscale metal-organic frameworks (NMOFs) for intracellular pH sensing in live cells. Fluorescein isothiocyanate (FITC) was covalently conjugated to a UiO NMOF to afford F-UiO NMOFs with exceptionally high FITC loadings, efficient fluorescence, and excellent ratiometric pH-sensing properties. Upon rapid and efficient endocytosis, F-UiO remained structurally intact inside endosomes. Live cell imaging studies revealed endo- and exocytosis of F-UiO and endosome acidification in real time. Fluorescently labeled NMOFs thus represent a new class of nanosensors for intracellular pH sensing and provide an excellent tool for studying NMOF-cell interactions.

Nanoscale metal-organic frameworks for the co-delivery of cisplatin and pooled siRNAs to enhance therapeutic efficacy in drug-resistant ovarian cancer cells.

Ovarian cancer is the leading cause of death among women with gynecological malignancies. Acquired resistance to chemotherapy is a major limitation for ovarian cancer treatment. We report here the first use of nanoscale metal-organic frameworks (NMOFs) for the co-delivery of cisplatin and pooled small interfering RNAs (siRNAs) to enhance therapeutic efficacy by silencing multiple drug resistance (MDR) genes and resensitizing resistant ovarian cancer cells to cisplatin treatment. UiO NMOFs with hexagonal-plate morphologies were loaded with a cisplatin prodrug and MDR gene-silencing siRNAs (Bcl-2, P-glycoprotein [P-gp], and survivin) via encapsulation and surface coordination, respectively. NMOFs protect siRNAs from nuclease degradation, enhance siRNA cellular uptake, and promote siRNA escape from endosomes to silence MDR genes in cisplatin-resistant ovarian cancer cells. Co-delivery of cisplatin and siRNAs with NMOFs led to an order of magnitude enhancement in chemotherapeutic efficacy in vitro, as indicated by cell viability assay, DNA laddering, and Annexin V staining. This work shows that NMOFs hold great promise in the co-delivery of multiple therapeutics for effective treatment of drug-resistant cancers.

Ternary polymeric nanoparticles for oral siRNA delivery.

PURPOSE: Poor stability and inefficient absorption in the intestinal tract are major barriers confronting oral delivery of siRNA. We aimed to uncover if ternary polymeric nanoparticles (cationic polymer/siRNA/anionic component) can overcome these obstacles through changing the formulation-related parameters. METHODS: Ternary polymeric nanoparticles were prepared by ionic gelation of chitosan, N-trimethyl chitosan (TMC), or thiolated trimethyl chitosan (TTMC) with tripolyphosphate (TPP) or hyaluronic acid (HA), and siRNA was simultaneously encapsulated. Structural stabilities and siRNA protection of these nanoparticles were assessed in simulated intestinal milieu. Their transport across ex vivo rat ileum, macrophage uptake, in vitro gene silencing, and in vivo biodistribution after oral administration were investigated. RESULTS: Ternary polymeric nanoparticles formed by TTMC, siRNA, and TPP (TTMC/siRNA/TPP nanoparticles) showed suitable structural stability and siRNA protection in the intestinal tract, good permeability across ex vivo rat ileum, superior cellular uptake and gene silencing efficiency in Raw 264.7 cells, and high systemic biodistribution after oral administration. CONCLUSIONS: TTMC/siRNA/TPP nanoparticles demonstrated efficient gene silencing in vitro and systemic biodistribution in vivo, therefore, they were expected to be potential vehicles for oral siRNA delivery.

Trimethyl chitosan-cysteine nanoparticles for systemic delivery of TNF-α siRNA via oral and intraperitoneal routes.

PURPOSE: The lack of effective delivery vehicles impedes in vivo applications of siRNA. The trimethyl chitosan-cysteine (TC) nanoparticles (NPs) were developed for in vivo delivery of tumor necrosis factor α (TNF-α) siRNA via oral gavage and intraperitoneal injection. METHODS: The nanoparticles formulated from TC conjugate of 100, 200, and 500 kDa were prepared through ionic gelation with sodium tripolyphosphate, termed as TC100 NPs, TC200 NPs, and TC500 NPs, respectively. They were evaluated in terms of stability, siRNA protection, cellular uptake and TNF-α knockdown in peritoneal exudates macrophage cells (PECs), and in vivo TNF-α silencing in acute hepatic injury mice. RESULTS: TC100 NPs exhibited poor stability in simulated physiological environment compared to TC200 NPs and TC500 NPs. Compared to TC500 NPs, TC200 NPs could significantly enhance in vitro and in vivo cellular uptake by PECs and facilitate cytoplasmic siRNA release, resulting in high in vitro and in vivo TNF-α knockdown. Superior TNF-α suppressing level was obtained with TC200 NPs via oral gavage rather than intraperitoneal injection. CONCLUSIONS: The efficacies of in vivo TNF-α silencing were related to the molecular weight of TC conjugate and the administration route, which would assist in the rational design of siRNA vehicles.

Supramolecular metal-based nanoparticles for drug delivery and cancer therapy.

Although conventional cancer therapies such as chemotherapy and radiotherapy prevail in clinic, they tend to have narrow therapeutic windows. Many chemotherapies have unfavorable pharmacokinetics while radiotherapy incurs radiotoxicity to normal tissues surrounding tumors. The chemical tunability of supramolecular metal-based nanoparticles (SMNPs) enables the incorporation of various therapeutics, including hydrophilic and hydrophobic chemotherapeutic drugs, photosensitizers, radiosensitizers, and biological therapeutics for more effective delivery to tumors. In this mini-review, we highlight recent advances in SMNPs, namely nanoscale coordination polymers and nanoscale metal-organic frameworks, for drug delivery and cancer therapy. We particularly focus on innovative uses of metal clusters, ligands, pores, and surface modifications to load various therapeutics into SMNPs and critical evaluations of the anticancer efficacies of SMNPs.

siRNA release kinetics from polymeric nanoparticles correlate with RNAi efficiency and inflammation therapy via oral delivery.

Despite many efforts in the rational design of nanoparticles (NPs) to overcome the biological barriers to small interfering RNA (siRNA) delivery for improving gene silencing efficiency, little is known about the correlations between siRNA release kinetics and RNA interference (RNAi) efficiency and inflammation therapy via oral delivery. On the basis of mannose-modified trimethyl chitosan-cysteine (MTC) polymers, seven types of MTC NPs containing tumor necrosis factor (TNF)-α siRNA were prepared through ionic gelation. The siRNA release kinetics from MTC NPs were finely tuned by adjusting the kinds and amounts of the crosslinkers involved. These MTC NPs exhibited no disparities in siRNA protection against enzymatic degradation in physiological fluids and cellular uptake in macrophages; however, they showed distinct in vitro siRNA release profiles and intracellular unpacking kinetics. MTC NPs with relatively rapid and sustained siRNA release were responsible for efficient, prompt, and prolonged RNAi, contributing to desired therapeutic efficacy in acute and chronic inflammatory murine models following oral delivery. However, MTC NPs insufficiently releasing siRNA could not elicit effective RNAi. Collectively, the present investigation might provide broad insights into the optimization of siRNA nanocarriers with respect to their release kinetics for improving RNAi efficacies aiming at different types of inflammatory diseases. STATEMENT OF SIGNIFICANCE: siRNA release kinetics in the cytoplasm and pathological characteristics of diseases themselves determine the therapeutic efficacy of siRNA delivery. Herein, by adjusting the kinds and amounts of the crosslinkers involved, we developed seven types of MTC NPs containing TNF-α siRNA with distinct siRNA release kinetics. MTC NPs with relatively rapid and sustained siRNA release were responsible for prompt and prolonged RNAi, respectively, contributing to desired therapeutic efficacy in acute and chronic inflammation following oral delivery. These results might provide broad insights into the optimization of siRNA nanocarriers in respect to their release kinetics for improving therapeutic outcomes toward different clinical requirements.

Low-dose X-ray radiotherapy-radiodynamic therapy via nanoscale metal-organic frameworks enhances checkpoint blockade immunotherapy.

Checkpoint blockade immunotherapy relies on energized cytotoxic T cells attacking tumour tissue systemically. However, for many cancers, the reliance on T cell infiltration leads to low response rates. Conversely, radiotherapy has served as a powerful therapy for local tumours over the past 100 years, yet is rarely sufficient to cause systemic tumour rejection. Here, we describe a treatment strategy that combines nanoscale metal-organic framework (nMOF)-enabled radiotherapy-radiodynamic therapy with checkpoint blockade immunotherapy for both local and systemic tumour elimination. In mouse models of breast and colorectal cancer, intratumorally injected nMOFs treated with low doses of X-ray irradiation led to the eradication of local tumours and, when loaded with an inhibitor of the immune checkpoint molecule indoleamine 2,3-dioxygenase, the irradiated nMOFs led to consistent abscopal responses that rejected distal tumours. By combining the advantages of local radiotherapy and systemic tumour rejection via synergistic X-ray-induced in situ vaccination and indoleamine 2,3-dioxygenase inhibition, nMOFs may overcome some of the limitations of checkpoint blockade in cancer treatment.

Nanoparticle formulations of cisplatin for cancer therapy.

The genotoxic agent cisplatin, used alone or in combination with radiation and/or other chemotherapeutic agents, is an important first-line chemotherapy for a broad range of cancers. The clinical utility of cisplatin is limited both by intrinsic and acquired resistance and dose-limiting normal tissue toxicity. That cisplatin shows little selectivity for tumor versus normal tissue may be a critical factor limiting its value. To overcome the low therapeutic ratio of the free drug, macromolecular, liposomal, and nanoparticle drug delivery systems have been explored toward leveraging the enhanced permeability and retention effect and promoting delivery of cisplatin to tumors. Here, we survey recent advances in nanoparticle formulations of cisplatin, focusing on agents that show promise in preclinical or clinical settings. WIREs Nanomed Nanobiotechnol 2016, 8:776-791. doi: 10.1002/wnan.1390 For further resources related to this article, please visit the WIREs website.

Core-shell nanoscale coordination polymers combine chemotherapy and photodynamic therapy to potentiate checkpoint blockade cancer immunotherapy.

Advanced colorectal cancer is one of the deadliest cancers, with a 5-year survival rate of only 12% for patients with the metastatic disease. Checkpoint inhibitors, such as the antibodies inhibiting the PD-1/PD-L1 axis, are among the most promising immunotherapies for patients with advanced colon cancer, but their durable response rate remains low. We herein report the use of immunogenic nanoparticles to augment the antitumour efficacy of PD-L1 antibody-mediated cancer immunotherapy. Nanoscale coordination polymer (NCP) core-shell nanoparticles carry oxaliplatin in the core and the photosensitizer pyropheophorbide-lipid conjugate (pyrolipid) in the shell (NCP@pyrolipid) for effective chemotherapy and photodynamic therapy (PDT). Synergy between oxaliplatin and pyrolipid-induced PDT kills tumour cells and provokes an immune response, resulting in calreticulin exposure on the cell surface, antitumour vaccination and an abscopal effect. When combined with anti-PD-L1 therapy, NCP@pyrolipid mediates regression of both light-irradiated primary tumours and non-irradiated distant tumours by inducing a strong tumour-specific immune response.

Self-assembled core-shell nanoparticles for combined chemotherapy and photodynamic therapy of resistant head and neck cancers.

Combination therapy enhances anticancer efficacy of both drugs via synergistic effects. We report here nanoscale coordination polymer (NCP)-based core-shell nanoparticles carrying high payloads of cisplatin and the photosensitizer pyrolipid, NCP@pyrolipid, for combined chemotherapy and photodynamic therapy (PDT). NCP@pyrolipid releases cisplatin and pyrolipid in a triggered manner to synergistically induce cancer cell apoptosis and necrosis. In vivo pharmacokinetic and biodistribution studies in mice show prolonged blood circulation times, low uptake in normal organs, and high tumor accumulation of cisplatin and pyrolipid. Compared to monotherapy, NCP@pyrolipid shows superior potency and efficacy in tumor regression (83% reduction in tumor volume) at low drug doses in the cisplatin-resistant human head and neck cancer SQ20B xenograft murine model. We elucidated the in vitro/vivo fate of the lipid layer and its implications on the mechanisms of actions. This study suggests multifunctional NCP core-shell nanoparticles as a versatile and effective drug delivery system for potential translation to the clinic.

Self-assembled nanoscale coordination polymers carrying siRNAs and cisplatin for effective treatment of resistant ovarian cancer.

Resistance to the chemotherapeutic agent cisplatin is a major limitation for the successful treatment of many cancers. Development of novel strategies to overcome intrinsic and acquired resistance to chemotherapy is of critical importance to effective treatment of ovarian cancer and other types of cancers. We have sought to re-sensitize resistant ovarian cancer cells to chemotherapy by co-delivering chemotherapeutics and pooled siRNAs targeting multi-drug resistance (MDR) genes using self-assembled nanoscale coordination polymers (NCPs). In this work, NCP-1 particles with trigger release properties were first constructed by linking cisplatin prodrug-based bisphosphonate bridging ligands with Zn(2+) metal-connecting points and then coated with a cationic lipid layer, followed by the adsorption of pooled siRNAs targeting three MDR genes including survivin, Bcl-2, and P-glycoprotein via electrostatic interactions. The resulting NCP-1/siRNA particles promoted cellular uptake of cisplatin and siRNA and enabled efficient endosomal escape in cisplatin-resistant ovarian cancer cells. By down-regulating the expression of MDR genes, NCP-1/siRNAs enhanced the chemotherapeutic efficacy as indicated by cell viability assay, DNA ladder, and flow cytometry. Local administration of NCP-1/siRNAs effectively reduced tumor sizes of cisplatin-resistant SKOV-3 subcutaneous xenografts. This work shows that the NCP-1/siRNA platform holds great promise in enhancing chemotherapeutic efficacy for the effective treatment of drug-resistant cancers.