Oral Delivery of Photopolymerizable Nanogels Loaded with Gemcitabine for Pancreatic Cancer Therapy: Formulation Design, and in vitro and in vivo Evaluations

Background

Gemcitabine (GEM) faces challenges of poor oral bioavailability and extensive first-pass metabolism. Currently, only injectable formulations are available for clinical use. Hence, there is an urgent demand for the development of advanced, efficacious, and user-friendly dosage forms to maintain its status as the primary treatment for pancreatic ductal adenocarcinoma (PDAC). Nanogels (NGs) offer a novel oral drug delivery system, ideal for hydrophilic compounds like GEM. This study aims to develop NGs tailored for GEM delivery, with the goal of enhancing cellular uptake and gastrointestinal permeability for improved administration in PDAC patients.

Methods

We developed cross-linked NGs via photopolymerization of methacryloyl for drug delivery of GEM. We reveal characterization, cytotoxicity, and cellular uptake studies in Caco-2 and MIA PaCa-2 cells. In addition, studies of in vitro permeability and pharmacokinetics were carried out to evaluate the bioavailability of the drug.

Results

Our results show NGs, formed via photopolymerization of methacryloyl, had a spherical shape with a size of 233.91±7.75 nm. Gemcitabine-loaded NGs (NGs-GEM) with 5% GelMA exhibited efficient drug loading (particle size: 244.07±19.52 nm). In vitro drug release from NGs-GEM was slower at pH 1.2 than pH 6.8. Cellular uptake studies indicated significantly enhanced uptake in both MIA PaCa-2 and Caco-2 cells. While there was no significant difference in GEM's AUC and Cmax between NGs-GEM and free-GEM groups, NGs-GEM showed markedly lower dFdU content (10.07 hr∙μg/mL) compared to oral free-GEM (19.04 hr∙μg/mL) after oral administration (p<0.01), highlighting NGs' efficacy in impeding rapid drug metabolism and enhancing retention.

Conclusion

In summary, NGs enhance cellular uptake, inhibit rapid metabolic degradation of GEM, and prolong retention after oral administration. These findings suggest NGs-GEM as a promising candidate for clinical use in oral pancreatic cancer therapy.

Deciphering the role of Enterococcus faecium cytidine deaminase in gemcitabine resistance of gallbladder cancer

Gemcitabine-based chemotherapy is a cornerstone of standard care for gallbladder cancer (GBC) treatment. Still, drug resistance remains a significant challenge, influenced by factors such as tumor-associated microbiota impacting drug concentrations within tumors. Enterococcus faecium, a member of tumor-associated microbiota, was notably enriched in the GBC patient cluster. In this study, we investigated the biochemical characteristics, catalytic activity, and kinetics of the cytidine deaminase of E. faecium (EfCDA). EfCDA showed the ability to convert gemcitabine to its metabolite 2',2'-difluorodeoxyuridine. Both EfCDA and E. faecium can induce gemcitabine resistance in GBC cells. Moreover, we determined the crystal structure of EfCDA, in its apo form and in complex with 2', 2'-difluorodeoxyuridine at high resolution. Mutation of key residues abolished the catalytic activity of EfCDA and reduced the gemcitabine resistance in GBC cells. Our findings provide structural insights into the molecular basis for recognizing gemcitabine metabolite by a bacteria CDA protein and may provide potential strategies to combat cancer drug resistance and improve the efficacy of gemcitabine-based chemotherapy in GBC treatment.

Biodegradable nanocarrier of gemcitabine and tocopherol succinate synergistically ameliorates anti-proliferative response in MIA PaCa-2 cells

Gemcitabine (GEM) is an important chemotherapeutic agent used alone or in combination with other anticancer agents for the treatment of various solid tumors. In this study, the potential of a dietary supplement, α-tocopherol succinate (TOS) was investigated in combination with GEM by utilizing human serum albumin-based nanoparticles (HSA NPs). The developed nanoparticles were characterized using DLS, SEM and FTIR and evaluated in a panel of cell lines to inspect cytotoxic efficacy. The ratio metric selected combination of the NPs was further investigated in human pancreatic cancer cell line (MIA PaCa-2 cells) to assess the cellular death mechanism via a myriad of biochemical and bio-analytical assays including nuclear morphometric analysis by DAPI staining, ROS generation, MMP loss, intracellular calcium release, in vitro clonogenic assay, cell migration assay, cell cycle analysis, immunocytochemical staining followed by western blotting, Annexin V-FITC and cellular uptake studies. The desolvation-crosslinking method was used to prepare the NPs. The average size of TOS-HSA NPs and GEM-HSA NPs was found to be 189.47 ± 5 nm and 143.42 ± 7.4 nm, respectively. In combination, the developed nanoparticles exhibited synergism by enhancing cytotoxicity in a fixed molar ratio. The selected combination also significantly triggered ROS generation and mitochondrial destabilization, alleviated cell migration potential and clonogenic cell survival in MIA PaCa-2 cells. Further, cell cycle analysis, Annexin-V FITC assay and caspase-3 activation, up regulation of Bax and down regulation of Bcl-2 protein confirmed the occurrence of apoptotic event coupled with the G0/G1 phase arrest. Nanocarriers based this combination also offered approximately 14-folds dose reduction of GEM. Overall, the combined administration of TOS-HSA NPs and GEM-HSA NPs showed synergistic cytotoxicity accompanied with dose reduction of the gemcitabine. These encouraging findings could have implication in designing micronutrient based-combination therapy with gemcitabine and demands further investigation.

Liposomal nanostructures for Gemcitabine and Paclitaxel delivery in pancreatic cancer

Pancreatic cancer (PC) is an incurable disease with a high death rate in the world nowadays. Gemcitabine (GEM) and Paclitaxel (PTX) are considered as references of chemotherapeutic treatments and are commonly used in clinical applications. Factors related to the tumor microenvironment such as insufficient tumor penetration, toxicity, and drug resistance can limit the effectiveness of these therapeutic anticancer drugs. The use of different liposomal nanostructures is a way that can optimize the drug's effectiveness and reduce toxicity. Given the development of PC therapy, this review focuses on advances in Nano-formulation, characterization, and delivery systems of loaded GEM and PTX liposomes using chemotherapy, nucleic acid delivery, and stroma remodeling therapy. As a result, the review covers the literature dealing with the applications of liposomes in PC therapy.

Self-Delivery Janus-Prodrug for Precise Immuno-Chemotherapy of Colitis-Associated Colorectal Cancer

Aromatized thioketal (ATK) linked the immunoregulatory molecule (budesonide, Bud) and the cytotoxic molecule (gemcitabine, Gem) to construct a ROS-activated Janus-prodrug, termed as BAG. Benefiting from the hydrogen bonding, π-π stacking, and other intermolecular interactions, BAG could self-assemble into nanoaggregates (BAG NA) with a well-defined spherical shape and uniform size distribution. Compared to the carrier-based drug delivery system, BAG NA have ultrahigh drug loading content and ROS concentration-dependent drug release. Colitis-associated colorectal cancer (CAC) is a typical disease in which chronic inflammation transforms into tumors. BAG NA can be internalized by colon cancer C26 cells and then triggered by excessive intracellular ROS to release nearly 100% of the drugs. Based on this, BAG NA showed a stronger pro-apoptotic effect than free Bud combined with free Gem. What is gratifying is that orally administered BAG NA can precisely accumulate in the diseased colon tissues of CAC mice induced by AOM/DSS and simultaneously release Bud and Gem. Bud can regulate the tumor immune microenvironment to restore and enhance the cytotoxicity of Gem. Therefore, BAG NA maximizes the synergistic therapeutic effect through co-delivery of Bud and Gem. This work provided a cutting-edge method for constructing self-delivery Janus-prodrug based on ATK and confirmed its potential application in inflammation-related carcinogenesis.

Two Possible Strategies for Drug Modification of Gemcitabine and Future Contributions to Personalized Medicine

Drug repurposing is an emerging strategy, which uses already approved drugs for new medical indications. One such drug is gemcitabine, an anticancer drug that only works at high doses since a portion is deactivated in the serum, which causes toxicity. In this review, two methods were discussed that could improve the anticancer effect of gemcitabine. The first is a chemical modification by conjugation with cell-penetrating peptides, namely penetratin, pVEC, and different kinds of CPP6, which mostly all showed an increased anticancer effect. The other method is combining gemcitabine with repurposed drugs, namely itraconazole, which also showed great cancer cell inhibition growth. Besides these two strategies, physiologically based pharmacokinetic models (PBPK models) are also the key for predicting drug distribution based on physiological data, which is very important for personalized medicine, so that the correct drug and dosage regimen can be administered according to each patient’s physiology. Taking all of this into consideration, it is believed that gemcitabine can be repurposed to have better anticancer effects.

N-trimethyl chitosan coated nano-complexes enhance the oral bioavailability and chemotherapeutic effects of gemcitabine

N-trimethyl chitosan (TMC) is a multifunctional polymer that can be used in various nanoparticle forms in the pharmaceutical, nutraceutical and biomedical fields. In this study, TMC was used as a mucoadhesive adjuvant to enhance the oral bioavailability and hence antitumour effects of gemcitabine formulated into nanocomplexes composed of poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) conjugated with d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). A central composite design was applied to achieve the optimal formulation. Cellular uptake and drug transportation studies revealed the nanocomplexes permeate over the intestinal cells via adsorptive-mediated and caveolae-mediated endocytosis. Pharmacokinetic studies demonstrated the oral drug bioavailability of the nanocomplexes was increased 5.1-fold compared with drug solution. In pharmacodynamic studies, the formulation reduced tumour size 3.1-fold compared with the drug solution. The data demonstrates that TMC modified nanocomplexes can enhance gemcitabine oral bioavailability and promote the anticancer efficacy.

Unified Description of Ultrafast Excited State Decay Processes in Epigenetic Deoxycytidine Derivatives

Epigenetic DNA modifications play a fundamental role in modulating gene expression and regulating cellular and developmental biological processes, thereby forming a second layer of information in DNA. The epigenetic 2'-deoxycytidine modification 5-methyl-2'-deoxycytidine, together with its enzymatic oxidation products (5-hydroxymethyl-2'-deoxycytidine, 5-formyl-2'-deoxycytidine, and 5-carboxyl-2'-deoxycytidine), are closely related to deactivation and reactivation of DNA transcription. Here, we combine sub-30-fs transient absorption spectroscopy with high-level correlated multiconfigurational CASPT2/MM computational methods, explicitly including the solvent, to obtain a unified picture of the photophysics of deoxycytidine-derived epigenetic DNA nucleosides. We assign all the observed time constants and identify the excited state relaxation pathways, including the competition of intersystem crossing and internal conversion for 5-formyl-2'-deoxycytidine and ballistic decay to the ground state for 5-carboxy-2'-deoxycytidine. Our work contributes to shed light on the role of epigenetic derivatives in DNA photodamage as well as on their possible therapeutic use.

Fabrication of dopamine conjugated with protein @metal organic framework for targeted drug delivery: A biocompatible pH-Responsive nanocarrier for gemcitabine release on MCF‑7 human breast cancer cells

Metal-organic structures (MOF), modern extremely proliferous materials consisting of metal ions and organic coordinating molecules, has become a promising biomedical material because of its unusual features, including great surface area, wide pore volume, flexible functionality and superior performance for drug loading. In the current investigation, Gemcitabine Hydrochloride (Gem), an anticancer drug, and Amygdalin (Amy) were loaded into a nanocomposite structure formed from bovine serum albumin (BSA) as a center and zeolytic imidazolate framework-8 (ZIF-8) as a pH sensitive protective coating. The formed BSA-Gem@ZIF-8 and BSA-Gem-Amy@ZIF-8 were successively coated by polydopamine, chelated by Au³⁺ and conjugated via gallic acid (GA), acquired ZIF-8 structure as a multifunctional nanocarrier at the end. It was confirmed by different characterization methods that the nanocarrier was successfully produced. Due to the nature of ZIF-8, pH dependent releases of BSA-Gem@ZIF-8/Dopa/GA and BSA-Gem-Amy@ZIF-8/Dopa/GA were observed in in vitro studies. Cytotoxicity and apoptotic effects of these nanocarriers were evaluated using WST-1 and acridine orange staining in MCF-7 human breast cancer and HUVEC control cell lines. In-vitro cytotoxicity studies showed that both BSA-Gem@ZIF-8/Dopa/GA and BSA-Gem-Amy@ZIF-8/Dopa/GA were more effective than gemcitabine alone in MCF-7 cells with less toxicity in HUVEC cells. Additionally, both pH-responsive nanocarriers induced more apoptotic cell death in MCF-7 cells. We therefore believe that the built multifunctional nanocarrier based on ZIF-8 could be an alternative therapeutic strategy the use of gemcitabine for cancer therapy.

Intragenomic Decarboxylation of 5-Carboxy-2'-deoxycytidine

Cellular DNA is composed of four canonical nucleosides (dA, dC, dG and T), which form two Watson-Crick base pairs. In addition, 5-methylcytosine (mdC) may be present. The methylation of dC to mdC is known to regulate transcriptional activity. Next to these five nucleosides, the genome, particularly of stem cells, contains three additional dC derivatives, which are formed by stepwise oxidation of the methyl group of mdC with the help of Tet enzymes. These are 5-hydroxymethyl-dC (hmdC), 5-formyl-dC (fdC), and 5-carboxy-dC (cadC). It is believed that fdC and cadC are converted back into dC, which establishes an epigenetic control cycle that starts with methylation of dC to mdC, followed by oxidation and removal of fdC and cadC. While fdC was shown to undergo intragenomic deformylation to give dC directly, a similar decarboxylation of cadC was postulated but not yet observed on the genomic level. By using metabolic labelling, we show here that cadC decarboxylates in several cell types, which confirms that both fdC and cadC are nucleosides that are directly converted back to dC within the genome by C-C bond cleavage.

A gemcitabine-based conjugate with enhanced antitumor efficacy by suppressing HIF-1α expression under hypoxia

Hypoxia is one of the unique features of tumor physiology. Hypoxia inducible factor (HIF-1α), as a major transcription factor in response to hypoxia, has been considered as a promising tumor-specific target for anticancer therapy. The formation of a hypoxic microenvironment in tumors can decrease the curative effect of cytotoxic chemotherapeutic drugs. To promote the antitumor efficacy of chemotherapy by suppressing hypoxia, we designed and prepared a novel gemcitabine-based drug conjugate (GEM-5) containing a HIF-1α inhibitor (YC-1). As expected, GEM-5 showed excellent antiproliferative activity (IC50 = 0.03 μΜ under hypoxia) and remarkably induced the apoptosis of A2780 cells in vitro. Additionally, western blot analysis demonstrated that GEM-5 significantly down-regulated the expression of HIF-1α and up-regulated the expression of tumor suppressor p53. More importantly, GEM-5 effectively inhibited tumor growth in the A2780 xenograft mouse model and significantly ameliorated tumor hypoxia in vivo. This novel, simple, and effective strategy for overcoming tumor hypoxia and enhancing the antitumor effect of chemotherapeutic drugs has great potential in cancer therapy.

The α-D-anomer of 2'-deoxycytidine: crystal structure, nucleoside conformation and Hirshfeld surface analysis

β-2'-Deoxyribonucleosides are the constituents of nucleic acids, whereas their anomeric α-analogues are rarely found in nature. Moreover, not much information is available on the structural and conformational parameters of α-2'-deoxyribonucleosides. This study reports on the single-crystal X-ray structure of α-2'-deoxycytidine, C9H13N3O4 (1), and the conformational parameters characterizing 1 were determined. The conformation at the glycosylic bond is anti, with χ = 173.4 (2)°, and the sugar residue adopts an almost symmetrical C2'-endo-C3'-exo twist (23T; S-type), with P = 179.7°. Both values lie outside the conformational range usually preferred by α-nucleosides. In addition, the amino group at the nucleobase shows partial double-bond character. This is supported by two separated signals for the amino protons in the 1H NMR spectrum, indicating a hindered rotation around the C4-N4 bond and a relatively short C-N bond in the solid state. Crystal packing is controlled by N-H...O and O-H...O contacts between the nucleobase and sugar moieties. Moreover, two weak C-H...N contacts (C1'-H1' and C3'-H3'A) are observed. A Hirshfeld surface analysis was carried out and the results support the intermolecular interactions observed by the X-ray analysis.

Nanoformulation of Apolipoprotein E3-Tagged Liposomal Nanoparticles for the co-Delivery of KRAS-siRNA and Gemcitabine for Pancreatic Cancer Treatment

PURPOSE

KRAS is the most frequently mutated gene in human cancers, and ~ 90% of pancreatic cancers exhibit KRAS mutations. Despite the well-known role of KRAS in malignancies, directly inhibiting KRAS is challenging.

METHODS

In this study, we successfully synthesized apolipoprotein E3-based liposomes for the co-delivery of gemcitabine (GEM) and a small interfering RNA targeting KRAS (KRAS-siRNA) to improve the efficacy of pancreatic cancer treatment.

RESULTS

Apolipoprotein E3 self-assembly on the liposome surface led to a substantial increase in its internalization in PANC1 human pancreatic cancer cells. KRAS-siRNA led to downregulated KRAS protein expression and KRAS-dependent carcinogenic pathways, resulting in the inhibition of cell proliferation, cell cycle arrest, increased apoptosis, and suppression of tumor progression. The combination of KRAS-siRNA and GEM induced a synergistic improvement in cell apoptosis and significantly lower cell viability compared with single-agent therapy. The low IC₅₀ value of A3-SGLP might be attributed to potentiation of the anticancer effect of GEM by siRNA-mediated silencing of KRAS mutations, thereby inducing synergistic effects on cancer cells.

CONCLUSION

A3-SGLP led to a marked decrease in the overall tumor burden and did not show any signs of toxicity. Therefore, the combination of KRAS-siRNA and GEM holds great potential for the treatment of pancreatic cancer.

Anti-tumor effects and cell motility inhibition of the DN604-gemcitabine combined treatment in human bladder cancer models

Bladder cancer is one of the major tumors for men in the world, in which therapy the combination of cisplatin and gemcitabine is still fist-line applied to treat with advanced or metastatic bladder cancer. In our early study, we developed a potential Pt(II) agent, DN604, which has anti-tumor effect as potent as cisplatin toward bladder cancers. Herein, we aim at investigating the combinatory application of DN604 with gemcitabine for bladder cancer treatment. In vitro studies proved that the combined treatment of DN604 and gemcitabine could limit cell proliferation by elevating the incidence of DNA damage induced apoptosis. Notably, further researches showed that the DN604-gemcitabine treatment suppressed cell autophagy to inhibit cell motility upon the ROS dependent p38 MAPK signaling pathway, explicating its better anti-tumor activity than single drug treatment or the cisplatin-gemcitabine treatment. In vivo tests confirmed that the DN604-gemcitabine treatment has superior anti-tumor activity with low toxicity to cisplatin or its combination with gemcitabine treatments. DN604 plus gemcitabine, is of great significance for the treatment with human bladder cancer. Our study has provided a potential combination treatment option.

Induction of potent cell growth inhibition by schizophyllan/K-ras antisense complex in combination with gemcitabine

Antisense oligonucleotides (AS-ODNs) specifically hybridize with target mRNAs, resulting in interference with the splicing mechanism or the regulation of protein translation. In our previous reports, we demonstrated that β-glucan schizophyllan (SPG) can form a complex with AS-ODNs attached with oligo deoxyadenosine dA₄₀ (AS-ODN-dA₄₀/SPG), and that this complex can be recognized by β-glucan receptor Dectin-1 on antigen presenting cells and lung cancer cells. In many types of cancer cell, activating K-ras mutations related to malignancy are frequently observed. In this study, we first designed 78 AS-ODNs for K-ras to optimize the sequence for highly efficient gene suppression. The selected AS-ODN (K-AS07) having dA₄₀ made a complex with SPG. The resultant complex (K-AS07-dA₄₀/SPG) showed an effect of silencing the ras gene in the cells (PC9: human adenocarcinoma differentiated from lung tissue) expressing Dectin-1, leading to the suppression of cell growth. Furthermore, the cytotoxic effect was enhanced when used in combination with the anticancer drug gemcitabine. Gemcitabine, a derivative of cytidine, was shown to interact with dA₄₀ in a sequence-dependent manner. This interaction did not appear to be so strong, with the gemcitabine being released from the complex after internalization into the cells. SPG and the dA₄₀ part of K-AS07-dA₄₀ play roles in carriers for K-AS07 and gemcitabine, respectively, resulting in a strong cytotoxic effect. This combination effect is a novel feature of the AS-ODN-dA₄₀/SPG complexes. These results could facilitate the clinical application of these complexes for cancer treatment.

Chitosan Hydrogels for Synergistic Delivery of Chemotherapeutics to Triple Negative Breast Cancer Cells and Spheroids

PURPOSE

This study aimed to develop a hydrogel system for treating aggressive triple negative breast cancer (TNBC) via kinetically-controlled delivery of the synergistic drug pair doxorubicin (DOX) and gemcitabine (GEM). A 2D assay was adopted to evaluate therapeutic efficacy by determining combination index (CI), and a 3D assay using cancer spheroids was implemented to assess the potential for translation in vivo.

METHODS

The release of DOX and GEM from an acetylated-chitosan (ACS, degree of acetylation χAc = 40 ± 5%) was characterized to identify a combined drug loading that affords release kinetics and dose that are therapeutically synergistic. The selected DOX/GEM-ACS formulation was evaluated in vitro with 2-D and 3-D models of TNBC to determine the combination index (CI) and the tumor volume reduction, respectively.

RESULTS

Therapeutically desired release dosages and kinetics of GEM and DOX were achieved. When evaluated with a 2-D model of TNBC, the hydrogel afforded a CI of 0.14, indicating a stronger synergism than concurrent administration of DOX and GEM (CI = 0.23). Finally, the therapeutic hydrogel accomplished a notable volume reduction of the cancer spheroids (up to 30%), whereas the corresponding dosages of free drugs only reduced growth rate.

CONCLUSIONS

The ACS hydrogel delivery system accomplishes drug release kinetics and molar ratio that affords strong therapeutically synergism. These results, in combination with the choice of ACS as affordable and highly abundant source material, provide a strong pre-clinical demonstration of the potential of the proposed system for complementing surgical resection of aggressive solid tumors.

A Pharmacokinetic and Pharmacodynamic Evaluation of the Anti-Hepatocellular Carcinoma Compound 4-N-Carbobenzoxy-gemcitabine (Cbz-dFdC)

Gemcitabine (dFdC) demonstrates significant effectiveness against solid tumors in vitro and in vivo; however, its clinical application is limited because it tends to easily undergo deamination metabolism. Therefore, we synthesized 4-N-carbobenzoxy-gemcitabine (Cbz-dFdC) as a lead prodrug and conducted a detailed pharmacokinetic, metabolic, and pharmacodynamic evaluation. After intragastric Cbz-dFdC administration, the C_max of Cbz-dFdC and dFdC was 451.1 ± 106.7 and 1656.3 ± 431.5 ng/mL, respectively. The T_max of Cbz-dFdC and dFdC was 2 and 4 h, respectively. After intragastric administration of Cbz-dFdC, this compound was mainly distributed in the intestine due to low carboxylesterase-1 (CES1) activity. Cbz-dFdC is activated by CES1 in both humans and rats. The enzyme kinetic curves were well fitted by the Michaelis–Menten equation in rats’ blood, plasma, and tissue homogenates and S9 of the liver and kidney, as well as human liver S9 and CES1 recombinase. The pharmacodynamic results showed that the Cbz-dFdC have a good antitumor effect in the HepG2 cell and in tumor-bearing mice, respectively. In general, Cbz-dFdC has good pharmaceutical characteristics and is therefore a good candidate for a potential prodrug.

Antitumor activity of gemcitabine hydrochloride loaded lipid polymer hybrid nanoparticles (LPHNs): In vitro and in vivo

The present study demonstrated the application of gemcitabine hydrochloride (GEM) loaded lipid polymer hybrid nanoparticles (LPHNs) for the enhancement the chemotherapeutic response. GEM, which is an anti-tumor drug, is frequently utilized for the treatment of non-small cell lung cancer, breast cancer and pancreatic cancer. GEM loaded LPHNs were formed and examined for pharmacokinetic profile and in vivo anticancer activity. Modified double emulsion solvent evaporation method was employed in the preparation of the LPHNs. Cytotoxicities of the GEM loaded LPHNs formulation were evaluated on MCF-7 and MDA-MB-231 cells by MTT assays. Pharmacokinetics and in vivo anticancer efficacy studies were conducted following intraperitoneal administration in female Sprague-Dawley rats. In vivo pharmacokinetic studies in rats exhibited the advantage of the GEM loaded LPHNs over commercial product Gemko® and the GEM loaded LPHNs had longer circulation time. The half-life of GEM in LPHNs formulation was notable advanced (4.2 folds) comparing to commercial product of GEM (native). These findings indicated that GEM loaded LPHNs can be used for enhancing antitumor efficacy for breast cancer treatment.

Physicochemical and in vitro cytotoxicity studies of inclusion complex between gemcitabine and cucurbit[7]uril host

Gemcitabine, a cytostatic drug from the pyrimidine antimetabolite group, exhibits limited storage stability and numerous side effects during therapy. One of the strategies to improve the effectiveness of therapy with such drugs is the use of supramolecular nano-containers, including dendrimers and macrocyclic compounds. The ability of gemcitabine to attach a proton in an aqueous environment necessitates the search for a carrier that is well-tolerated by an organism and capable of supramolecular binding of a ligand (drug) in a cationic form. In the current study a promising strategy was tested for using cucurbituril Q7 to bind gemcitabine cations for its efficient intracellular delivery on three selected cancer cell lines (MOLT4, THP-1 and U937). Based on physicochemical studies (equilibrium dialysis, UV and ¹H NMR titrations, DOSY ¹H NMR measurements, DSC calorimetry) and cytotoxicity tests on cells with a free and blocked hENT1 transporter, the conclusion was drawn about the binding and penetration of the cucurbituril-drug complex into cancer cells.

Pediatric glioblastoma target-specific efficient delivery of gemcitabine across the blood-brain barrier via carbon nitride dots

Pediatric glioblastomas are known to be one of the most dangerous and life-threatening cancers among many others regardless of the low number of cases reported. The major obstacles in the treatment of these tumors can be identified as the lack of prognosis data and the therapeutic requirement to be able to cross the blood-brain barrier (BBB). Due to this lack of data and techniques, pediatric patients could face drastic side effects over a long-time span even after survival. Therefore, in this study, the capability of non-toxic carbon nitride dots (CNDs) to selectively target pediatric glioblastoma cells was studied in vitro. Furthermore, the nanocarrier capability and efficiency of CNDs were also investigated through conjugation of a chemotherapeutic agent and transferrin (T_f) protein. Gemcitabine (GM) was introduced into the system as a chemotherapeutic agent, which has never been successfully used for the treatment of any central nervous system (CNS) cancer. More than 95% of selective damage of SJGBM2 glioma cells was observed at 1 μM of CN-GM conjugate with almost 100% viability of non-cancerous HEK293 cells, although this ability was diminished at lower concentrations. However, further conjugation of T_f to obtain CN-GM-T_f allowed the achievement of selective targeting and prominent anti-cancer activity at a 100-fold lower concentration of 10 nM. Furthermore, both conjugates were capable of effectively damaging several other brain tumor cells, which were not well responsive towards the single treatment of GM. The capability of BBB penetration of the conjugates was observed using a zebrafish model, which confirms the CNDs' competence as an excellent nanocarrier to the CNS.

Triple drugs co-delivered by a small gemcitabine-based carrier for pancreatic cancer immunochemotherapy

Poor tumor penetration and highly immunosuppressive tumor microenvironment are two major factors that limit the therapeutic efficacy for the treatment of pancreatic ductal adenocarcinoma (PDA). In this work, a redox-responsive gemcitabine (GEM)-conjugated polymer, PGEM, was employed as a tumor penetrating nanocarrier to co-load an immunomodulating agent (NLG919, an inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1) and a chemotherapeutic drug (paclitaxel (PTX)) for immunochemo combination therapy. The NLG919/PTX co-loaded micelles showed very small size of ~15 nm. In vivo tumor imaging study indicated that PGEM was much more effective than the relatively large-sized POEG-co-PVD nanoparticles (~160 nm) in deep tumor penetration and could reach the core of the pancreatic tumor. PTX formulated in the PGEM carrier showed improved tumor inhibition effect compared with PGEM alone. Incorporation of NLG919 in the formulation led to a more immunoactive tumor microenvironment with significantly decreased percentage of Treg cells, and increased percentages of CD4+ IFNγ+ T and CD8+ IFNγ+ T cells. PGEM micelles co-loaded with PTX and NLG919 showed the best anti-tumor activity in pancreatic (PANC02) as well as two other tumor models compared to PGEM micelles loaded with PTX or NLG919 alone, suggesting that codelivery of NLG919 and PTX via PGEM may represent an effective strategy for immunochemotherapy of PDA as well as other types of cancers. STATEMENT OF SIGNIFICANCE: In order to effectively accumulate and penetrate the PDA that is poorly vascularized and enriched with dense fibrotic stroma, the size of nanomedicine has to be well controlled. Here, we reported an immunochemotherapy regimen based on co-delivery of GEM, PTX and IDO1 inhibitor NLG919 through an ultra-small sized GEM-based nanocarrier (PGEM). We demonstrated that the PGEM carrier was effective in accumulating and penetrating into PDA tumors. Besides, PGEM co-loaded with PTX and NLG9 induced an improved anti-tumor immune response and was highly efficacious in inhibiting tumor growth as well as in prolonging the survival rate in PANC02 xenograft model. Our work represents a potential strategy for enhancing PDA tumor penetration and immunochemotherapy.

Novel drug combination nanoparticles exhibit enhanced plasma exposure and dose-responsive effects on eliminating breast cancer lung metastasis

Early diagnosis along with new drugs targeted to cancer receptors and immunocheckpoints have improved breast cancer survival. However, full remission remains elusive for metastatic breast cancer due to dose-limiting toxicities of heavily used, highly potent drug combinations such as gemcitabine and paclitaxel. Therefore, novel strategies that lower the effective dose and improve safety margins could enhance the effect of these drug combinations. To this end, we developed and evaluated a novel drug combination of gemcitabine and paclitaxel (GT). Leveraging a simple and scalable drug-combination nanoparticle platform (DcNP), we successfully prepared an injectable GT combination in DcNP (GT DcNP). Compared to a Cremophor EL/ethanol assisted drug suspension in buffer (CrEL), GT DcNP exhibits about 56-fold and 8.6-fold increases in plasma drug exposure (area under the curve, AUC) and apparent half-life of gemcitabine respectively, and a 2.9-fold increase of AUC for paclitaxel. Using 4T1 as a syngeneic model for breast cancer metastasis, we found that a single GT (20/2 mg/kg) dose in DcNP nearly eliminated colonization in the lungs. This effect was not achievable by a CrEL drug combination at a 5-fold higher dose (i.e., 100/10 mg/kg GT). A dose-response study indicates that GT DcNP provided a therapeutic index of ~15.8. Collectively, these data suggest that GT DcNP could be effective against advancing metastatic breast cancer with a margin of safety. As the DcNP formulation is intentionally designed to be simple, scalable, and long-acting, it may be suitable for clinical development to find effective treatment against metastatic breast cancer.

Potent in vitro activity of β-D-4'-chloromethyl-2'-deoxy-2'-fluorocytidine against Nipah virus

Nipah virus (NiV) is a highly pathogenic zoonotic paramyxovirus that continues to cause outbreaks in humans characterized by high mortality and significant clinical sequelae in survivors. Currently, no therapeutics are approved for use in humans against NiV infection. Here, we report that 4'-chloromethyl-2'-deoxy-2'-fluorocytidine (ALS-8112) inhibits NiV. ALS-8112 is the parent nucleoside of lumicitabine, which has been evaluated in phase I and II clinical trials to treat pediatric and adult respiratory syncytial virus infection. In this study, we tested ALS-8112 against NiV and other major human respiratory pneumo- and paramyxoviruses in 2 human lung epithelial cell lines, and demonstrated the ability of ALS-8112 to reduce infectious wild-type NiV yield by over 6 orders of magnitude with no apparent cytotoxicity. However, further cytotoxicity testing in primary cells and bone marrow progenitor cells indicated cytotoxicity at higher concentrations of ALS-8112. Our results warrant the evaluation of lumicitabine against NiV infection in relevant animal models.

Quantification of fluorophore distribution and therapeutic response in matched in vivo and ex vivo pancreatic cancer model systems

Therapeutic resistance plagues cancer outcomes, challenging treatment particularly in aggressive disease. A unique method to decipher drug interactions with their targets and inform therapy is to employ fluorescence-based screening tools; however, to implement productive screening assays, adequate model systems must be developed. Patient-derived pancreatic cancer models (e.g., cell culture, patient-derived xenograft mouse models, and organoids) have been traditionally utilized to predict personalized therapeutic response. However, cost, long read out times and the inability to fully recapitulate the tumor microenvironment have rendered most models incompatible with clinical decision making for pancreatic ductal adenocarcinoma (PDAC) patients. Tumor explant cultures, where patient tissue can be kept viable for up to weeks, have garnered interest as a platform for delivering personalized therapeutic prediction on a clinically relevant timeline. To fully explore this ex vivo platform, a series of studies were completed to quantitatively compare in vivo models with tumor explants, examining gemcitabine therapeutic efficacy, small molecule uptake and drug-target engagement using a novel fluorescently-labeled gemcitabine conjugate. This initial work shows promise for patient-specific therapeutic selection, where tumor explant drug distribution and response recapitulated the in vivo behavior and could provide a valuable platform for understanding mechanisms of therapeutic response and resistance.

Targeting Pancreatic Cancer Cells and Stellate Cells Using Designer Nanotherapeutics in vitro

INTRODUCTION AND OBJECTIVE

Pancreatic cancer (PC) is characterized by a robust desmoplastic environment, which limits the uptake of the standard first-line chemotherapeutic drug gemcitabine. Enhancing gemcitabine delivery to the complex tumor microenvironment (TME) is a major clinical challenge. Molecular crosstalk between pancreatic cancer cells (PCCs) and pancreatic stellate cells (PSCs) plays a critical role in desmoplastic reaction in PCs. Herein, we report the development of a targeted drug delivery system to inhibit the proliferation of PCCs and PSCs in vitro. Using gold nanoparticles as the delivery vehicle, the anti-EGFR antibody cetuximab (C225/C) as a targeting agent, gemcitabine as drug and polyethylene glycol (PEG) as a stealth molecule, we created a series of targeted drug delivery systems.

METHODS

Fabricated nanoconjugates were characterized by various physicochemical techniques such as UV-Visible spectroscopy, transmission electron microscopy, HPLC and instrumental neutron activation analysis (INAA).

RESULTS AND CONCLUSION

Targeted gemcitabine delivery systems containing mPEG-SH having molecular weights of 550 Da or 1000 Da demonstrated superior efficacy in reducing the viability of both PCCs and PSCs as compared to their non-targeted counterparts. EGFR-targeted pathway was further validated by pre-treating cells with C225 followed by determining cellular viability. Taken together, in our current study we have developed a PEGylated targeted nanoconjugate ACG44P1000 that showed enhanced selectivity towards pancreatic cancer cells and pancreatic stellate cells, among others, for gemcitabine delivery. We will investigate the ability of these optimized conjugates to inhibit desmoplasia and tumor growth in vivo in our future studies.

Biodegradable Polymeric Multilayer Capsules for Therapy of Lung Cancer

Formulated forms of cancer therapeutics enhance the efficacy of treatment by more precise targeting, increased bioavailability of drugs, and an aptitude of some delivery systems to overcome multiple drug resistance of tumors. Drug carriers acquire importance for anti-cancer interventions via targeting tumor-associated macrophages with active molecules capable to either eliminate them or change their polarity. Although several packaged drug forms have reached the market, there is still a high demand for novel carrier systems to hurdle limitations of existing drugs on active molecules, toxicity, bioeffect, and stability. Here, we report a facile assembly and delivery methodology for biodegradable polymeric multilayer capsules (PMC) with the purpose of further use in injectable drug formulations for lung cancer therapy via direct erosion of tumors and suppression of the tumor-promoting function of macrophages in the tumor microenvironment. We demonstrate delivery of low-molecular-weight drug molecules to lung cancer cells and macrophages and provide details on in vivo distribution, cellular uptake, and disintegration of the developed PMC. Poly-l-arginine and dextran sulfate alternately adsorb on a ∼500 nm CaCO₃ sacrificial template followed by removal of the inorganic core to obtain hollow capsules for consequent loading with drug molecules, gemcitabine or clodronate. The capsules further compacted upon loading down to ∼250 nm in diameter via heat treatment. A comparative study of the capsule internalization rate in vitro and in vivo reveals the benefits of a diminished carrier size. We show that macrophages and epithelial cells of the lungs and liver internalize capsules with efficacy higher than 75%. Using an in vivo mouse model of lung cancer, we also confirm that tumor lungs better retain smaller capsules than the healthy lung tissue. The pronounced cytotoxic effect of the encapsulated gemcitabine on lung cancer cells and the ability of the encapsulated clodronate to block the tumor-promoting function of macrophages prove the efficacy of the developed capsule loading method in vitro. Our study taken as a whole demonstrates the great potential of the developed PMC for in vivo treatment of cancer via transporting active molecules, including those that are water-soluble with low molecular weight, to both cancer cells and macrophages through the bloodstream.

Self-Assembled Gemcitabine Prodrug Nanoparticles Show Enhanced Efficacy against Patient-Derived Pancreatic Ductal Adenocarcinoma

Effective new therapies for pancreatic ductal adenocarcinoma (PDAC) are desperately needed as the prognosis of PDAC patients is dismal and treatment remains a major challenge. Gemcitabine (GEM) is commonly used to treat PDAC; however, the clinical use of GEM has been greatly compromised by its low delivery efficacy and drug resistance. Here, we describe a very simple yet cost-effective approach that synergistically combines drug reconstitution, supramolecular nanoassembly, and tumor-specific targeting to address the multiple challenges posed by the delivery of the chemotherapeutic drug GEM. Using our developed PUFAylation technology, the GEM prodrug was able to spontaneously self-assemble into colloidal stable nanoparticles with sub-100 nm size on covalent attachment of hydrophobic linoleic acid via amide linkage. The prodrug nanoassemblies could be further refined by PEGylation and PDAC-specific peptide ligand for preclinical studies. In vitro cell-based assays showed that not only were GEM nanoparticles superior to free GEM but also the decoration with PDAC-homing peptide facilitated the intracellular uptake of nanoparticles and thereby augmented the cytotoxic activity. In two separate xenograft models of human PDAC, one of which was a patient-derived xenograft model, the administration of targeted nanoparticles resulted in marked inhibition of tumor progression as well as alleviated systemic toxicity. Together, these data unequivocally confirm that the hydrophilic and rapidly metabolized drug GEM can be feasibly transformed into a pharmacologically efficient nanomedicine through exploiting the PUFAylation technology. This strategy could also potentially be applied to rescue many other therapeutics that show unfavorable outcomes in the preclinical studies because of pharmacologic obstacles.

Combination of Doxorubicin with Gemcitabine-Incorporated G-Quadruplex Aptamer Showed Synergistic and Selective Anticancer Effect in Breast Cancer Cells

Doxorubicin (DOX) is one of the most effective anticancer agents used for the treatment of multiple cancers; however, its use is limited by its short half-life and adverse drug reactions, especially cardiotoxicity. In this study, we found that the conjugate of DOX with APTA12 (Gemcitabine incorporated G-quadruplex aptamer) was significantly more cancer selective and cytotoxic than DOX. The conjugate had an affinity for nucleolin, with higher uptake and retention into the cancer cells than those of DOX. Further, it was localized to the nucleus, which is the target site of DOX. Owing to its mechanism of action, DOX has the ability to intercalate into the nucleotides thus making it a suitable drug to form a conjugate with cancer selective aptamers such as APTA12. The conjugation can lead to selectively accumulate in the cancer cells thus decreasing its potential nonspecific as well as cardiotoxic side effects. The aim of this study was to prepare a conjugate of DOX with APTA12 and assess the chemotherapeutic properties of the conjugate specific to cancer cells. The DOX-APTA12 conjugate was prepared by incubation and its cytotoxicity in MCF-10A (non-cancerous mammary cells) and MDA-MB-231 (breast cancer cells) was assessed. The results indicate that DOX-APTA12 conjugate is a potential option for chemotherapy especially for nucleolin expressing breast cancer with reduced doxorubicin associated side effects.

pH-Responsive and Gemcitabine-Containing DNA Nanogel To Facilitate the Chemodrug Delivery

Herein, we construct a structure-switchable gemcitabine (Ge)-containing DNA nanogel that can respond to the intracellular acidic environment, subsequently facilitating the chemodrug release inside the cells. Based on the structural similarity between Ge and deoxycytidine (dC), dC nucleotides in the component DNA strands used for nanogel assembly are fully replaced by Ge during their synthesis. By changing the designed sequences, two Ge-containing Y-shaped motifs with different sticky ends are first assembled and then associated together to form nanogel by sticky-end hybridizations. In particular, one of the sticky-end sequences is arbitrarily designed to be rich of Ge and the other is designed to be partially complementary to the first Ge-rich sticky end. At the neutral or basic condition, the Ge-rich sticky ends hybridize with the partially complementary sticky ends on the second Y motifs, keeping the assembled nanogel stable. Upon being exposed to the acidic condition, Ge-rich sticky ends intend to form intramolecular i-motif-like quadruplex structures, resulting in the disassembly of the nanogel. On the one hand, the nanosized feature enables the Ge-containing nanogel with rapid cellular uptake behavior. On the other hand, the pH-responsive feature endows the rapid disassembly of the nanogel to facilitate the enzymatic drug release inside the cell, resulting in the enhanced anticancer activity of the DNA-based drug delivery system.

Combination of Gemcitabine with Cell-Penetrating Peptides: A Pharmacokinetic Approach Using In Silico Tools

Gemcitabine is an anticancer drug used to treat a wide range of solid tumors and is a first line treatment for pancreatic cancer. Our group has previously developed novel conjugates of gemcitabine with cell-penetrating peptides (CPP), and here we report some preliminary data regarding the pharmacokinetics of gemcitabine, two gemcitabine-CPP conjugates and respective CPP gathered from GastroPlus™, and analyze these results considering our previous evaluation of gemcitabine release and conjugates’ bioactivity. Additionally, seeking to shed some light on the relation between the penetration ability of CPP and their physicochemical properties, chemical descriptors for the 20 natural amino acids were calculated, a new principal property scale (z-scale) was created and CPP prediction models were developed, establishing quantitative structure-activity relationships (QSAR). The z-scores of the peptides conjugated with gemcitabine are presented and analyzed with the aforementioned data.

Cyanine-Gemcitabine Conjugates as Targeted Theranostic Agents for Glioblastoma Tumor Cells

A small subset of heptamethine dyes (cyanine-7 or Cy7) share an intriguing characteristic: preferential tumor accumulation and retention. These dyes absorb in the near-infrared (NIR) region (above 750 nm) and perform active targeting to deliver therapeutic and toxic cargoes to various tumor models in vivo. In this work, four heptamethines 1 were synthesized, which have a gemcitabine fragment attached to the meso-position of the Cy7 core. Theranostic agent 1a was discovered that localized in glioblastoma tumor cells, has absorption maxima in NIR region, and showed similar therapeutic effect to gemcitabine but at one-third the molar dose.

Design and Evaluation of PEGylated Liposomal Formulation of a Novel Multikinase Inhibitor for Enhanced Chemosensitivity and Inhibition of Metastatic Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has one of the highest mortality rates among cancers. Chemotherapy is the standard first-line treatment, but only modest survival benefits are observed. With the advent of targeted therapies, epidermal growth factor receptor (EGFR) has been acknowledged as a prospective target in PDAC since it is overexpressed in up to 60% of cases. Similarly, the tyrosine-protein kinase Met (cMET) is also overexpressed in PDAC (27-60%) and is a prognostic marker for poor survival. Interestingly, EGFR and cMET share some common signaling pathways including PI3K/Akt and MAPK pathways. Small molecule inhibitors or bispecific antibodies that can target both EGFR and cMET are therefore emerging as novel options for cancer therapy. We previously developed a dual EGFR and cMET inhibitor (N19) that was able to inhibit tumor growth in nonsmall cell lung cancer models resistant to EGFR tyrosine kinase inhibitors (TKI). Here, we report the development of a novel liposomal formulation of N19 (LN19) and showed significant growth inhibition and increased sensitivity toward gemcitabine in the pancreatic adenocarcinoma orthotopic xenograft model. Taken together, our results suggest that LN19 can be valued as an effective combination therapy with conventional chemotherapy such as gemcitabine for PDAC patients.

Chemoresistance in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC), generally known as pancreatic cancer (PC), ranks the fourth leading cause of cancer-related deaths in the western world. While the incidence of pancreatic cancer is displaying a rising tendency every year, the mortality rate has not decreased significantly because of late diagnosis, early metastasis, and limited reaction to chemotherapy or radiotherapy. Adjuvant chemotherapy after surgical resection is typically the preferred option to treat early pancreatic cancer. Although 5-fluorouracil/leucovorin with irinotecan and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel can profoundly improve the prognosis of advanced pancreatic cancer, the development of chemoresistance still leads to poor clinical outcomes. Chemoresistance is multifactorial as a result of the interaction among pancreatic cancer cells, cancer stem cells, and the tumor microenvironment. Nevertheless, more pancreatic cancer patients will benefit from precision treatment and targeted drugs. Therefore, we outline new perspectives for enhancing the efficacy of gemcitabine after reviewing the related factors of gemcitabine metabolism, mechanism of action, and chemoresistance.

Fluorescein-Stabilized i-Motif DNA and Its Unfolding Leading to a Stronger Adsorption Affinity

Several previous studies have indicated that polydeoxycytidine (poly-C) DNA has an anomalously high affinity for different types of surfaces. It was hypothesized that the formation of an i-motif structure could be a factor responsible for this enhanced affinity, but this is against the notion that a folded molecule should have fewer interactions with a surface. Herein, the properties of poly-C DNA were examined in detail, focusing on the presence or absence of a FAM (carboxyfluorescein) label and its subsequent adsorption on graphene oxide. Fluorescence and CD spectroscopy studies indicated that FAM can stabilize an i-motif structure in C15 DNA. In particular, the fluorescence of FAM is drastically quenched when the DNA is folded. This structure is irreversibly unfolded upon heating. Furthermore, the unfolded structure has an even higher affinity for graphene oxide than the folded structure. Finally, a large portion of the folded C15 unfolds upon desorption from graphene oxide, and unfolding could happen upon adsorption or desorption of the DNA. This study provides a method to further enhance the adsorption stability of poly-C DNA and calls for care when investigating the potential effects of dye labels on DNA.

RGDV-modified gemcitabine: a nano-medicine capable of prolonging half-life, overcoming resistance and eliminating bone marrow toxicity of gemcitabine

BACKGROUND

Gemcitabine has been widely used as a chemotherapeutic drug. However, drug resistance, short half-life and side effects seriously decrease its chemotherapeutic efficacy.

PURPOSE

The object of preparing RGDV-gemcitabine was to prolong the half-life, to overcome drug resistance and to eliminate bone marrow toxicity of gemcitabine.

METHODS

Arg-Gly-Asp-Val was coupled with gemcitabine, forming 4-(Arg-Gly-Asp-Val-amino)-1-[3,3-difluoro-4-hydroxy-5-(hydroxylmethyl)oxo-lan-2-yl]pyrimidin-2-one (RGDV-gemcitabine) involving 9-step reactions. The advantages of RGDV-gemcitabine to gemcitabine were demonstrated by a series of assays, such as in vitro half-life assay, in vitro drug resistance assay, in vivo anti-tumor assay, in vivo kidney toxicity assay, in vivo liver toxicity assay and in vivo marrow toxicity assay. The nano-features of RGDV-gemcitabine were visualized by TEM, SEM and AFM images. The tumor-targeting action and release of RGDV-gemcitabine were evidenced by FT-MS spectra.

RESULTS

Half-life and anti-tumor activity of RGDV-gemcitabine were 17-fold longer and 10-fold higher than that of gemcitabine, respectively. RGDV-gemcitabine, but not gemcitabine, showed no kidney toxicity, no liver toxicity, no marrow toxicity and no drug resistance. The advantages attributed to the nanofeatures of RGDV-gemcitabine were targeting tumor tissue and releasing gemcitabine in tumor tissue.

CONCLUSION

RGDV-gemcitabine successively overcame the defects of gemcitabine and provided a practical strategy of nano-medicine.

A solid lipid nanoparticle formulation of 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine with increased solubility, stability, and antitumor activity

Previously, we synthesized 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine (DHA-dFdC), a novel lipophilic compound with a potent, broad-spectrum antitumor activity. Herein, we report a solid lipid nanoparticle (SLN) formulation of DHA-dFdC with improved apparent aqueous solubility, chemical stability, as well as efficacy in a mouse model. The SLNs were prepared from lecithin/glycerol monostearate-in-water emulsions emulsified with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and Tween 20. The resultant DHA-dFdC-SLNs were 102.2 ± 7.3 nm in diameter and increased the apparent solubility of DHA-dFdC in water to at least 5.2 mg/mL, more than 200-fold higher than its intrinsic water solubility. DHA-dFdC in a lyophilized powder of DHA-dFdC-SLNs was significantly more stable than the waxy solid of pure DHA-dFdC. DHA-dFdC-SLNs also showed an increased cytotoxicity against certain tumor cells than DHA-dFdC. The plasma concentration of DHA-dFdC in mice intravenously injected with DHA-dFdC-SLNs in dispersion followed a bi-exponential model, with a half-life of ~44 h. In mice bearing B16-F10 murine melanoma, DHA-dFdC-SLNs were significantly more effective than DHA-dFdC in controlling the tumor growth. In addition, histology evaluation revealed a high level of apoptosis and tumor encapsulation in tumors in mice treated with DHA-dFdC-SLNs. DHA-dFdC-SLNs represents a new DHA-dFdC formulation with improved antitumor activity.

Acoustic disruption of tumor endothelium and on-demand drug delivery for cancer chemotherapy

Chemotherapy has been the most widely used treatment against cancer, however, it is limited by its systemic toxicity as well as resistance developed by tumors' physical barriers. Herein, we propose a novel acoustically-mediated treatment regime to on-demand release therapeutics and disrupt tumor structures. By programming a high intensity focused ultrasound transducer, we can locally and digitally release gemcitabine (GEM) as well as open the local blood-tumor barrier or even tumor stroma to enhance intratumor drug delivery via acoustically-oscillating bubbles and liposomes. In our experiments, we modeled tumor endothelium by culturing a monolayer of murine endothelial cells (2H11) on transwell membrane. We locally disrupted the cultured endothelium to enhance drug penetration by using perfluorocarbon liquid droplets as breaking probes and protoporphyrin IX hybridized liposomes as drug carriers. We also demonstrated an on-demand release of GEM by digitally triggering the break of drug carriers. Moreover, we validated the acoustic tumor endothelium disruption in vivo by monitoring penetration of dye (Evans blue) in solid tumors. Therefore, we present an acoustically-mediated delivery method that both releases drug on-demand locally and opens the blood-tumor barrier to enhance drug penetration. This sets the ground for further clinical cancer therapy to improve many systemic cancer treatments.

Light-Cross-linked Enediyne Small-Molecule Micelle-Based Drug-Delivery System

Light-cross-linked small-molecule micelles with enediyne units are designed for developing efficient drug-delivery systems. Gemcitabine (GEM) is chosen as a model hydrophilic drug and tethered with a maleimide-based enediyne (EDY) as a hydrophobic tail in the preparation of amphiphilic EDY-GEM. The stable micellar particles are obtained by cross-linking the enediyne moieties via photoinduced Bergman cyclization polymerization in aqueous media. The light-cross-linked spherical micelles with a size of 80 nm are characterized with dynamic light scattering and electron microscopy, showing robust micellar stability, bright fluorescent emission due to their intrinsic conjugated structure, and potential passive tumor-targeting ability through the enhanced permeability and retention effect. The drug-loaded micelles, as an example of light-cross-linked small-molecule micelle-based drug-delivery system, exhibit high drug-loading contents (50%) and greatly improved cytotoxicity toward A549 cells (decreasing the IC₅₀ value of Gemcitabine by 10 times), thanks to the greatly increased cellular uptake of the drug-loaded micelles as confirmed by confocal laser scanning microscopy. The light-cross-linked enediyne-based small-molecule micelles system therefore provides a simple yet efficient drug-delivery platform for cancer chemotherapy.

Drug combination using an injectable nanomedicine hydrogel for glioblastoma treatment

Lauroyl-gemcitabine lipid nanocapsules (GemC₁₂-LNC) hydrogel, administered intratumorally or perisurgically in the tumor resection cavity, increases animal survival in several orthotopic GBM models. We hypothesized that GemC₁₂-LNC can be used as nanodelivery platform for other drugs, to obtain a combined local therapeutic approach for GBM. Paclitaxel (PTX) was selected as a model molecule and PTX-GemC₁₂-LNC formulation was evaluated in terms of physicochemical and mechanical properties. The PTX-GemC₁₂-LNC hydrogel stability and drug release were evaluated over time showing no significant differences compared to GemC₁₂-LNC. The drug combination was evaluated on several GBM cell lines showing increased cytotoxic activity compared to the original formulation and synergy between PTX and GemC₁₂. Our results suggest that GemC₁₂-LNC hydrogel can be used as nanodelivery platform for dual drug delivery to encapsulate active agents with different mechanisms of action to achieve a better antitumor efficacy against GBM or other solid tumors.

Normalized Retention Time for Targeted Analysis of the DNA Adductome

A wide spectrum of DNA lesions can be generated from byproducts of endogenous metabolism and/or from environmental exposure. A DNA adductomic approach for the robust quantification of DNA adducts in cellular and tissue DNA may facilitate the use of DNA adducts for biomonitoring studies and enable comprehensive assessment about DNA repair. Normalized retention time (iRT) has been widely used in scheduled selected-reaction monitoring (SRM) methods for highly sensitive and high-throughput analyses of protein samples in complicated matrices. By using a similar method, we established the iRT scores for 36 modified nucleosides from the retention times of the four canonical 2'-deoxynucleosides on a nanoflow liquid chromatography-nanospray ionization-tandem mass spectrometry (nLC-NSI-MS/MS) system. The iRT scores facilitated reliable prediction of retention time and were employed for establishing a scheduled SRM method for quantitative assessment of a subset of the DNA adductome. The quantification results of the scheduled SRM method were more accurate and precise than those from an unscheduled method.

Synthesis of Fluorescence Turn-On DNA Hybridization Probe Using the DEA tC 2'-Deoxycytidine Analog

DEA tC is a tricyclic 2'-deoxycytidine analog that can be incorporated into oligonucleotides by solid-phase synthesis and that exhibits a large fluorescence enhancement when correctly base-paired with a guanine base in a DNA-DNA duplex. The synthesis of DEA tC begins with 5-amino-2-methylbenzothiazole and provides the DEA tC nucleobase analog over five synthetic steps. This nucleobase analog is then silylated using N,O-bis(trimethylsilyl)acetamide and conjugated to Hoffer's chlorosugar to provide the protected DEA tC nucleoside in good yield. Following protective-group removal and chromatographic isolation of the β-anomer, dimethoxytritylation and phosphoramidite synthesis offer the monomer for solid-phase DNA synthesis. Solid-phase DNA synthesis conditions using extended coupling of the DEA tC amidite and a short deprotection time are employed to maximize efficiency. By following the protocols described in this unit, the DEA tC fluorescent probe can be synthesized and can be incorporated into any desired synthetic DNA oligonucleotide. © 2018 by John Wiley & Sons, Inc.

Application of Integrated Drug Screening/Kinome Analysis to Identify Inhibitors of Gemcitabine-Resistant Pancreatic Cancer Cell Growth

Continuous exposure of a pancreatic cancer cell line MIA PaCa-2 (MiaS) to gemcitabine resulted in the formation of a gemcitabine-resistant subline (MiaR). In an effort to discover kinase inhibitors that inhibited MiaR growth, MiaR cells were exposed to kinase inhibitors (PKIS-1 library) in a 384-well screening format. Three compounds (UNC10112721A, UNC10112652A, and UNC10112793A) were identified that inhibited the growth of MiaR cells by more than 50% (at 50 nM). Two compounds (UNC10112721A and UNC10112652A) were classified as cyclin-dependent kinase (CDK) inhibitors, whereas UNC10112793A was reported to be a PLK inhibitor. Dose-response experiments supported the efficacy of these compounds to inhibit growth and increase apoptosis in 2D cultures of these cells. However, only UNC10112721A significantly inhibited the growth of 3D spheroids composed of MiaR cells and GFP-tagged cancer-associated fibroblasts. Multiplexed inhibitor bead (MIB)-mass spectrometry (MS) kinome competition experiments identified CDK9, CLK1-4, DYRK1A, and CSNK1 as major kinase targets for UNC10112721A in MiaR cells. Another CDK9 inhibitor (CDK-IN-2) replicated the growth inhibitory effects of UNC10112721A, whereas inhibitors against the CLK, DYRK, or CSNK1 kinases had no effect. In summary, these studies describe a coordinated approach to discover novel kinase inhibitors, evaluate their efficacy in 3D models, and define their specificity against the kinome.

Localized Controlled Delivery of Gemcitabine via Microsol Electrospun Fibers to Prevent Pancreatic Cancer Recurrence

The low radical surgery rate of pancreatic cancer leads to increased local recurrence and poor prognosis. Gemcitabine (GEM) is the preferred chemotherapeutic for pancreatic cancer. However, systemic chemotherapy with GEM has reached a bottleneck due to its serious side effects after frequent injections. In this study, GEM is successfully enwrapped into electrospun fibers via microsol electrospinning technology to form a stable core-shell fibrous structure. The GEM release rate can be adjusted by altering the thickness of the hyaluronan-sol inner fiber and the quantity of loaded GEM, and the release can be sustained for as long as three weeks. In vitro assays show that these electrospun fibers effectively inhibit pancreatic cancer cells and promote apoptosis. In vivo studies show that the fibrous membranes are better for inhibiting the growth of residual tumors than that of integrated tumors. Furthermore, immunohistochemistry results show that GEM-loaded fibers promote a higher cell apoptosis rate than does systemically injected GEM in residual tumors. In addition, the local delivery of GEM with fibers significantly reduces liver toxicity. In summary, a core-shell electrospun fiber for the controlled and localized delivery of GEM, which greatly improves the treatment of residual tumors and prevents pancreatic tumor recurrence, is developed.

Carrier-free Janus nano-prodrug based on camptothecin and gemcitabine: Reduction-triggered drug release and synergistic in vitro antiproliferative effect in multiple cancer cells

A carrier-free and reduction-degradable Janus prodrug, termed as CPT-SS-GEM, was fabricated by redox-sensitive disulfide bond linked gemcitabine and camptothecin. This amphiphilic prodrug showed high drug loading capacity, 42.6% of CPT and 32.2% of GEM, respectively. Benefiting from its amphiphilic property, CPT-SS-GEM prodrug could self-assemble into Janus nano-prodrug in water without aid of any excipient. The morphology of the nano-prodrug was spherical particle confirmed by TEM. The rapid drug release from the nano-prodrug proceeded in a reduction-dependent manner, more than 90% of the native CPT and GEM were released in the mimic microenvironment of tumor cells (pH 6.5 PBS containing 2 mM DTT) within a period of 3 h. The concurrent and ratio-metric release of CPT and GEM endowed the Janus nano-prodrug CPT-SS-GEM with pronounced in vitro synergistic antiproliferative effect in multiple cancer cell lines when the inhibition rate of cancer cell proliferation exceeded 50%, including A549, NCI-H460, HCT116, HT-29, and MCF-7/ADR. The combination index values showed as followings, 1.04-0.4 (A549), 0.24-0.60 (NCI-H460), 0.42-0.16 (HCT116), 1.98-0.15 (HT-29), 0.36-0.19 (MCF-7/ADR). Taken together, the carrier-free, redox-sensitive Janus nano-prodrug CPT-SS-GEM is a promising candidate as synergistic combination of chemotherapeutics.

Stereocomplex Prodrugs of Oligo(lactic acid) n-Gemcitabine in Poly(ethylene glycol)- block-poly(d,l-lactic acid) Micelles for Improved Physical Stability and Enhanced Antitumor Efficacy

Herein we demonstrate the formation of stereocomplex prodrugs of oligo(l-lactic acid) _n-gemcitabine (o(LLA) _n-GEM) and oligo(d-lactic acid) _n-gemcitabine (o(DLA) _n-GEM) for stable incorporation in poly(ethylene glycol)- block-poly(d,l-lactic acid) (PEG- b-PLA) micelles. O(LLA) _n or o(DLA) _n was attached at the amino group (4-( N)) of GEM via an amide linkage. When n = 10, a 1:1 mixture of o(LLA)₁₀-GEM and o(DLA)₁₀-GEM (o(L+DLA)₁₀-GEM) was able to form a stereocomplex with a distinctive crystalline pattern. Degradation of o(L+DLA)₁₀-GEM was driven by both backbiting conversion and esterase contribution, generating primarily o(L+DLA)₁-GEM and GEM. O(L+DLA)₁₀-GEM stably loaded in PEG- b-PLA micelles in the size range of 140-200 nm with an unexpected elongated morphology. The resulting micelles showed improved physical stability in aqueous media and inhibited backbiting conversion of o(L+DLA)₁₀-GEM within micelles. Release of o(L+DLA)₁₀-GEM from micelles was relatively slow, with a t_1/2 at ca. 60 h. Furthermore, weekly administration of o(L+DLA)₁₀-GEM micelles i.v. displayed potent antitumor activity in an A549 human non-small-cell lung carcinoma xenograft model. Thus, stereocomplexation of isotactic o(LLA) _n and o(DLA) _n acts as a potential prodrug strategy for improved stability and sustained drug release in PEG- b-PLA micelles.

Gemcitabine hydrochloride microspheres used for intravesical treatment of superficial bladder cancer: a comprehensive in vitro/ex vivo/in vivo evaluation

INTRODUCTION

Bladder cancer is responsible for more than 130,000 deaths annually worldwide. Intravesical delivery of chemotherapeutic agents provides effective drug localization to the target area to reduce toxicity and increase efficacy. This study aimed to develop an intravesical delivery system of gemcitabine HCl (Gem-HCl) to provide a sustained-release profile, to prolong residence time, and to enhance its efficiency in the treatment of bladder cancer.

MATERIALS AND METHODS

For this purpose, bioadhesive microspheres were successfully prepared with average particle size, encapsulation efficiency, and loading capacity of 98.4 µm, 82.657%±5.817%, and 12.501±0.881 mg, respectively. For intravesical administration, bioadhesive microspheres were dispersed in mucoadhesive chitosan or in situ poloxamer gels and characterized in terms of gelation temperature, viscosity, mechanical, syringeability, and bioadhesive and rheological properties. The cytotoxic effects of Gem-HCl solution, Gem-HCl microspheres, and Gem-HCl microsphere-loaded gel formulations were evaluated in two different bladder cancer cell lines: T24 (ATCC HTB4TM) and RT4 (ATCC HTB2TM).

RESULTS

According to cell-culture studies, Gem-HCl microsphere-loaded poloxamer gel was more cytotoxic than Gem-HCl microsphere-loaded chitosan gel. Antitumor efficacy of newly developed formulations were investigated by in vivo studies using bladder-tumor-induced rats.

CONCLUSION

According to in vivo studies, Gem-HCl microsphere-loaded poloxamer gel was found to be an effective and promising alternative for current intravesical delivery-system therapies.

A carbon nanotube-gemcitabine-lentinan three-component composite for chemo-photothermal synergistic therapy of cancer

PURPOSE

Gemcitabine's clinical application is limited due to its short plasma half-life and poor uptake by cells. To address this problem, a drug delivery three-component composite, multiwalled carbon nanotubes (MWNTs)/gemcitabine (Ge)/lentinan (Le; MWNTs-Ge-Le), was fabricated in our study. Moreover, the combination of chemotherapy and photothermal therapy was employed to enhance antitumor efficacy.

METHODS

In this study, we conjugated gemcitabine and lentinan with MWNTs via a covalent and noncovalent way to functionalize with MWNTs, and the chemical structure of MWNTs-Ge-Le was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and transmission electron microscopy. Using the composite and an 808 nm laser, we treated tumors, both in vitro and in vivo, and investigated the photothermal responses and the anticancer efficacy.

RESULTS

The MWNTs-Ge-Le composite could efficiently cross cell membrane, having a higher antitumor activity than MWNTs, gemcitabine and MWNTs-Ge in vitro and in vivo. Our study on the MWNTs-Ge-Le composite with an 808 nm laser radiation showed the combination of drug therapy and near-infrared photothermal therapy possesses great synergistic antitumor efficacy.

CONCLUSION

The MWNTs-Ge-Le three-component anticancer composite can serve as a promising candidate for cancer therapy in the combination of chemotherapy and photothermal therapy.

TMSOTf assisted synthesis of 2'-deoxy-2'-[18F]fluoro-β-D-arabinofuranosylcytosine ([18F]FAC)

[¹⁸F]FAC (2’-deoxy-2’-[¹⁸F]fluoro-β-D-arabinofuranosylcytosine, 1) is a versatile probe for imaging deoxycytidine kinase (dCK) expression levels in vivo. dCK is responsible for phosphorylation of deoxycytidine (dC, 2) and other nucleoside analogs, plays a key role in immune activation and has demonstrated to be one of the key enzymes in activating nucleoside based drugs including gemcitabine. Reported synthesis of [¹⁸F]FAC is high yielding but is quite challenging requiring bromination using HBr and careful drying of excess HBr which is critical for successful synthesis. Here in we report a simplified trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted synthesis of [¹⁸F]FAC eliminating the need of bromination and drying. [¹⁸F]FAC (β-anomer) was synthesized with average isolated decay corrected yield of 10.59 + 4.2% (n = 6) with radiochemical purity of >98% and total synthesis time of 158 + 19 min.

Capecitabine: Indications and Future Perspectives in the Treatment of Metastatic Colorectal and Breast Cancer

Fluoropyrimidines remain the most important drugs in the treatment of breast and colorectal carcinoma, but response rates and survival time have been disappointing. Optimal administration is by continuous intravenous infusion, which makes it cumbersome to use and compromises patient independence. Recently, a number of new agents, including fluorouracil prodrugs and selective dihydropyrimidine dehydrogenase inhibitors, have been studied, with promising results. Capecitabine is the first in a new class of fluoropyrimidines. It is an oral, tumor-activated anticancer drug whose activity mimics that of continuously infused 5-fluorouracil. Capecitabine circumvents dihydropyrimidine dehydrogenase catabolism and appears to be at least as active against metastatic colorectal and breast cancer as conventionally administered intravenous 5-fluorouracil, with significantly less toxicity, an improved quality of life, and lesser cost. Capecitabine may ultimately provide enhanced antitumor activity to fluorouracil-containing regimes for advanced colorectal and breast cancer.

The 4-N-acyl and 4-N-alkyl gemcitabine analogues with silicon-fluoride-acceptor: Application to 18F-Radiolabeling

The coupling of gemcitabine with functionalized carboxylic acids using peptide coupling conditions afforded 4-N-alkanoyl analogues with a terminal alkyne or azido moiety. Reaction of 4-N-tosylgemcitabine with azidoalkyl amine provided 4-N-alkyl gemcitabine with a terminal azido group. Click reaction with silane building blocks afforded 4-N-alkanoyl or 4-N-alkyl gemcitabine analogues suitable for fluorination. RP-HPLC analysis indicated better chemical stability of 4-N-alkyl gemcitabine analogues versus 4-N-alkanoyl analogues in acidic aqueous conditions. The 4-N-alkanoyl gemcitabine analogues showed potent cytostatic activity against L1210 cell line, but cytotoxicity of the 4-N-alkylgemcitabine analogues was low. However, 4-N-alkanoyl and 4-N-alkyl analogues had comparable antiproliferative activities in the HEK293 cells. The 4-N-alkyl analogue with a terminal azide group was shown to be localized inside HEK293 cells by fluorescence microscopy after labelling with Fluor 488-alkyne. The [18F]4-N-alkyl or alkanoyl silane gemcitabine analogues were successfully synthesized using microscale and conventional silane-labeling radiochemical protocols. Preliminary positron-emission tomography (PET) imaging in mice showed the biodistribution of [18F]4-N-alkyl to have initial concentration in the liver, kidneys and GI tract followed by increasing signal in the bone.