Pharmacokinetics of chloroquine in patients with malaria by P. vivax from the Western Brazilian Amazon basin.

The western Amazon basin is an important endemic area for malaria by P. vivax. In recent years, several reports showed the treatment failure with chloroquine, which can be related to resistance. The assessment of chloroquine resistance requires the evaluation of drug exposure, and when possible, the estimation of the pharmacokinetic parameters. However, there is no data on the pharmacokinetics of chloroquine in this endemic area. Moreover, the influence of the early reappearance of parasites in blood on the exposure to the drug was low exploited in the literature. The present study described the pharmacokinetic parameters of chloroquine in whole blood of adult patients with P. vivax malaria from the western Brazilian Amazon basin and compared the area under the curve (AUC) with the parasitological outcome at day 28. A total of 19 patients with parasite recurrence within 28 days and 20 patients with no recurrence were included in the study. Chloroquine was measured by high-performance liquid chromatography (HPLC). The pharmacokinetic parameters were estimated by non-compartmental modeling. The maximum concentration ranged from 1285 to 2030 ng/mL. The terminal half-life varied from 5.3 to 12.8 days. The volume of distribution from 1090 to 2340 L/kg, and the area under the curve to the last measurable concentration from 247 to 432 ng/mL.h. The pharmacokinetic parameters were similar in both groups, which suggests the lack of influence of early reappearance of parasites on chloroquine pharmacokinetics.

Pharmacokinetics of chloroquine and primaquine in healthy volunteers.

BACKGROUND: Vivax malaria is a neglected disease. There is an irrefutable need for better treatments with higher acceptability and efficacy. The treatment efficacy is influenced by many factors, including bioavailability. Hence, a straightforward strategy to improve vivax malaria treatment efficacy is the deployment of good quality formulations of primaquine and chloroquine. As these treatments were developed more than 70 years ago, many of the available data on blood levels of both drugs are based on obsolete analytical methodologies or pharmaceutical formulations, which are not available anymore. Herein, the results of three bioequivalence studies are presented, providing individual pharmacokinetic data on chloroquine and primaquine of more than a hundred healthy volunteers and using up-to-date analytical methods. METHODS: Three trials were designed as a single centre, randomized, single dose, open label, fasting, crossover bioequivalence studies comparing a new coated chloroquine tablet to the uncoated tablet, and 5 and 15 mg primaquine formulations to either an international reference product or the currently distributed tablets. Plasma concentrations of chloroquine and primaquine were measured using a validated HPLC-MS/MS method in accordance with current international regulatory requirements for bio-analytical methods. RESULTS: In total, a hundred eleven healthy volunteers of both genders were included in the three studies (n = 32; 30 and 56 respectively). No serious adverse events occurred. Drugs levels were measured in 5,520 blood samples. The estimated ratio of the geometric means of Cmax, AUC0-t and AUC0-inf of test and reference drugs and their 90% CI for chloroquine 150 mg, primaquine 15 mg and primaquine 5 mg were: 95.33% (89.18; 101.90), 86. 85% (82.61; 91.31), and 84.45% (76.95; 92.67); 93.28% (81.76; 106.41), 94.52% (86.13; 103.73) and 93.93% (85.83; 102.79); 97.44% (90.60; 104.78), 93.70% (87.04; 100.87) and 91.36% (85.27; 97.89), respectively. As Cmax and AUC0-t 90% CI were within the acceptance interval of 80-125% in all cases, the formulations tested were bioequivalent. CONCLUSIONS: In conclusion, the three studies provided detailed chloroquine and primaquine pharmacokinetic data in accordance with current regulatory standards. Together with other open data initiatives, this individual data may increase the accuracy of pharmacokinetic models guiding best dose, new combinations, regimens and formulations to optimize the current chloroquine and primaquine treatments for vivax malaria. The data presented here may support the deployment of high-quality drugs and evidence-based public health policies.

Translational Modeling of Chloroquine and Hydroxychloroquine Dosimetry in Human Airways for Treating Viral Respiratory Infections.

PURPOSE: Chloroquine and hydroxychloroquine are effective against respiratory viruses in vitro. However, they lack antiviral efficacy upon oral administration. Translation of in vitro to in vivo exposure is necessary for understanding the disconnect between the two to develop effective therapeutic strategies. METHODS: We employed an in vitro ion-trapping kinetic model to predict the changes in the cytosolic and lysosomal concentrations of chloroquine and hydroxychloroquine in cell lines and primary human airway cultures. A physiologically based pharmacokinetic model with detailed respiratory physiology was used to predict regional airway exposure and optimize dosing regimens. RESULTS: At their reported in vitro effective concentrations in cell lines, chloroquine and hydroxychloroquine cause a significant increase in their cytosolic and lysosomal concentrations by altering the lysosomal pH. Higher concentrations of the compounds are required to achieve similar levels of cytosolic and lysosomal changes in primary human airway cells in vitro. The predicted cellular and lysosomal concentrations in the respiratory tract for in vivo oral doses are lower than the in vitro effective levels. Pulmonary administration of aerosolized chloroquine or hydroxychloroquine is predicted to achieve high bound in vitro-effective concentrations in the respiratory tract, with low systemic exposure. Achieving effective cytosolic concentrations for activating immunomodulatory effects and adequate lysosomal levels for inhibiting viral replication could be key drivers for treating viral respiratory infections. CONCLUSION: Our analysis provides a framework for extrapolating in vitro effective concentrations of chloroquine and hydroxychloroquine to in vivo dosing regimens for treating viral respiratory infections.

Interactions of primaquine and chloroquine with PEGylated phosphatidylcholine liposomes.

This study aimed to analyze the interaction of primaquine (PQ), chloroquine (CQ), and liposomes to support the design of optimal liposomal delivery for hepatic stage malaria infectious disease. The liposomes were composed of hydrogenated soybean phosphatidylcholine, cholesterol, and distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy[polyethyleneglycol]-2000), prepared by thin film method, then evaluated for physicochemical and spectrospic characteristics. The calcein release was further evaluated to determine the effect of drug co-loading on liposomal membrane integrity. The results showed that loading PQ and CQ into liposomes produced changes in the infrared spectra of the diester phosphate and carbonyl ester located in the polar part of the phospholipid, in addition to the alkyl group (CH2) in the nonpolar portion. Moreover, the thermogram revealed the loss of the endothermic peak of liposomes dually loaded with PQ and CQ at 186.6 °C, which is identical to that of the phospholipid. However, no crystallinity changes were detected through powder X-ray diffraction analysis. Moreover, PQ, with either single or dual loading, produced the higher calcein release profiles from the liposomes than that of CQ. The dual loading of PQ and CQ tends to interact with the polar head group of the phosphatidylcholine bilayer membrane resulted in an increase in water permeability of the liposomes.

Combination Chemotherapy with Cisplatin and Chloroquine: Effect of Encapsulation in Micelles Formed by Self-Assembling Hybrid Dendritic-Linear-Dendritic Block Copolymers.

Clinical outcomes of conventional drug combinations are not ideal due to high toxicity to healthy tissues. Cisplatin (CDDP) is the standard component for many cancer treatments, yet its principal dose-limiting side effect is nephrotoxicity. Thus, CDDP is commonly used in combination with other drugs, such as the autophagy inhibitor chloroquine (CQ), to enhance tumor cell killing efficacy and prevent the development of chemoresistance. In addition, nanocarrier-based drug delivery systems can overcome chemotherapy limitations, decreasing side effects and increasing tumor accumulation. The aim of this study was to evaluate the toxicity of CQ and CDDP against tumor and non-tumor cells when used in a combined treatment. For this purpose, two types of micelles based on Pluronic® F127 hybrid dendritic-linear-dendritic block copolymers (HDLDBCs) modified with polyester or poly(esteramide) dendrons derived from 2,2'-bis(hydroxymethyl)propionic acid (HDLDBC-bMPA) or 2,2'-bis(glycyloxymethyl)propionic acid (HDLDBC-bGMPA) were explored as delivery nanocarriers. Our results indicated that the combined treatment with HDLDBC-bMPA(CQ) or HDLDBC-bGMPA(CQ) and CDDP increased cytotoxicity in tumor cells compared to the single treatment with CDDP. Encapsulations demonstrated less short-term cytotoxicity individually or when used in combination compared to the free drugs. However, and more importantly, a low degree of cytotoxicity against non-tumor cells was maintained, even when drugs were given simultaneously.

HPLC methods for choloroquine determination in biological samples and pharmaceutical products.

OBJECTIVE: Review and assess pharmaceutical and clinical characteristics of chloroquine including high-performance liquid chromatography (HPLC)-based methods used to quantify the drug in pharmaceutical products and biological samples. EVIDENCE ACQUISITION: A literature review was undertaken on the PubMed, Science Direct, and Scielo databases using the following keywords related to the investigated subject: 'chloroquine', 'analytical methods', and 'HPLC'. RESULTS: For more than seven decades, chloroquine has been used to treat malaria and some autoimmune diseases, such as lupus erythematosus and rheumatoid arthritis. There is growing interest in chloroquine as a therapeutic alternative in the treatment of HIV, Q fever, Whipple's disease, fungal, Zika, Chikungunya infections, Sjogren's syndrome, porphyria, chronic ulcerative stomatitis, polymorphic light eruption, and different types of cancer. HPLC coupled to UV detectors is the most employed method to quantify chloroquine in pharmaceutical products and biological samples. The main chromatographic conditions used to identify and quantify chloroquine from tablets and injections, degradation products, and metabolites are presented and discussed. CONCLUSION: Research findings reported in this article may facilitate the repositioning, quality control, and biological monitoring of chloroquine in modern pharmaceutical dosage forms and treatments.

Chloroquine and Hydroxychloroquine Interact Differently with ACE2 Domains Reported to Bind with the Coronavirus Spike Protein: Mediation by ACE2 Polymorphism.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection inducing coronavirus disease 2019 (COVID-19) is still an ongoing challenge. To date, more than 95.4 million have been infected and more than two million deaths have been officially reported by the WHO. Angiotensin-converting enzyme (ACE) plays a key role in the disease pathogenesis. In this computational study, seventeen coding variants were found to be important for ACE2 binding with the coronavirus spike protein. The frequencies of these allele variants range from 3.88 × 10-3 to 5.47 × 10-6 for rs4646116 (K26R) and rs1238146879 (P426A), respectively. Chloroquine (CQ) and its metabolite hydroxychloroquine (HCQ) are mainly used to prevent and treat malaria and rheumatic diseases. They are also used in several countries to treat SARS-CoV-2 infection inducing COVID-19. Both CQ and HCQ were found to interact differently with the various ACE2 domains reported to bind with coronavirus spike protein. A molecular docking approach revealed that intermolecular interactions of both CQ and HCQ exhibited mediation by ACE2 polymorphism. Further explorations of the relationship and the interactions between ACE2 polymorphism and CQ/HCQ would certainly help to better understand the COVID-19 management strategies, particularly their use in the absence of specific vaccines or drugs.

Clearance of chloroquine and hydroxychloroquine by the Seraph® 100 Microbinda Affinity Blood Filter -a device approved for the treatment of COVID-19 patients.

On April 17 2020, the United States Food and Drug Administration granted Coronavirus Disease 2019 (COVID-19) emergency use authorizations for the Seraph 100 Microbind Affinity Blood Filter. The medical device is aimed to treat critically ill COVID-19 patients with confirmed or imminent respiratory failure. The aim of this life size in vitro pharmacokinetic study was to investigate the in vitro adsorption of chloroquine and hydroxychloroquine from human plasma using equipment that is also used at the bedside. After start of the hemoperfusion, Pre (Cpre ) Seraph plasma levels were obtained at 5 (C5 ), 10 (C10 ), 15 (C15 ), 30 (C30 ), 60 (C60 ), and 120 (C120 ) minutes into the procedure. At two timepoints (5 and 120 minutes) post (Cpost ) Seraph plasma levels were determined that were used to calculate the plasma clearance of the Seraph. Both drugs were determined using a validated HPLC method. Median [IQR] plasma clearance of the Seraph for chloroquine/hydroxychloroquine was 1.71 [0.51-4.38] mL/min/1.79 [0.21-3.68] mL/min respectively. The lack of elimination was also confirmed by the fact that plasma levels did not change over the 120 minutes treatment. As neither chloroquine nor hydroxychloroquine were removed by the treatment with the Seraph dose adjustments in COVID-19 patients undergoing this treatment are not necessary.

Physiologically Based Pharmacokinetics of Lysosomotropic Chloroquine in Rat and Human.

A semimechanistic physiologically based pharmacokinetic (PBPK) model for chloroquine (CQ), a highly lysosomotropic weak base, was applied to digitized rat and human concentration versus time data. The PBPK model in rat featured plasma and red blood cell (RBC) concentrations, extensive and apparent nonlinear tissue distribution, fitted hepatic and renal intrinsic clearances, and a plasma half-life of about 1 day. Tissue-to-plasma CQ ratios at 50 hours after dosing were highest in lung, kidney, liver, and spleen (182-318) and lower in heart, muscle, brain, eye, and skin (11-66). The RBC-to-plasma ratio of 11.6 was assumed to reflect cell lipid partitioning. A lysosome-based extended model was used to calculate subcellular CQ concentrations based on tissue mass balances, fitted plasma, interstitial and free cytosol concentrations, and literature-based pH and pKa values. The CQ tissue component concentrations ranked as follows: lysosome > > acidic phospholipid > plasma = interstitial = cytosol ≥ neutral lipids. The extensive lysosome sequestration appeared to change over time and was attributed to lowering pH values caused by proton pump influx of hydrogen ions. The human-to-rat volume of distribution (Vss) ratio of 7 used to scale rat tissue partitioning to human along with estimation of hepatic clearance allowed excellent fitting of oral-dose PK (150-600 mg) of CQ with a 50-day half-life in humans. The prolonged PK of chloroquine was well characterized for rat and human with this PBPK model. The calculated intratissue concentrations and lysosomal effects have therapeutic relevance for CQ and other cationic drugs. SIGNIFICANCE STATEMENT: Sequestration in lysosomes is a major factor controlling the pharmacokinetics and pharmacology of chloroquine and other cationic drugs. This report provides comprehensive physiologic modeling of chloroquine distribution in tissues and overall disposition in rat and human that reveals expected complexities and inferences related to its subcellular association with various tissue components.

Population-based meta-analysis of chloroquine: informing chloroquine pharmacokinetics in COVID-19 patients.

AIMS: Chloroquine (CQ) has been repurposed to treat coronavirus disease 2019 (COVID-19). Understanding the pharmacokinetics (PK) in COVID-19 patients is essential to study its exposure-efficacy/safety relationship and provide a basis for a possible dosing regimen optimization. SUBJECT AND METHODS: In this study, we used a population-based meta-analysis approach to develop a population PK model to characterize the CQ PK in COVID-19 patients. An open-label, single-center study (ethical review approval number: PJ-NBEY-KY-2020-063-01) was conducted to assess the safety, efficacy, and pharmacokinetics of CQ in patients with COVID-19. The sparse PK data from 50 COVID-19 patients, receiving 500 mg CQ phosphate twice daily for 7 days, were combined with additional CQ PK data from 18 publications. RESULTS: A two-compartment model with first-order oral absorption and first-order elimination and an absorption lag best described the data. Absorption rate (ka) was estimated to be 0.559 h-1, and a lag time of absorption (ALAG) was estimated to be 0.149 h. Apparent clearance (CL/F) and apparent central volume of distribution (V2/F) was 33.3 l/h and 3630 l. Apparent distribution clearance (Q/F) and volume of distribution of peripheral compartment (Q3/F) were 58.7 l/h and 5120 l. The simulated CQ concentration under five dosing regimens of CQ phosphate were within the safety margin (400 ng/ml). CONCLUSION: Model-based simulation using PK parameters from the COVID-19 patients shows that the concentrations under the currently recommended dosing regimen are below the safety margin for side-effects, which suggests that these dosing regimens are generally safe. The derived population PK model should allow for the assessment of pharmacokinetics-pharmacodynamics (PK-PD) relationships for CQ when given alone or in combination with other agents to treat COVID-19.

Clinical Probe of Cyp2C8*2 Mutants in a Malaria Hyperendemic Zone: Evidence from North-Central, Nigeria.

BACKGROUND: A tremendous level of success has been achieved since the introduction of chloroquine and the combination of amodiaquine and artemisinin for the treatment of both complicated and uncomplicated malaria infections in sub-Saharan Africa. However, the recent discovery of drug resistant strains of Plasmodium falciparum (P.f.) and the ability of the parasite to ingest CYP2C8 into its digestive vacuole is of great public health concern. This study probes the occurrence of CYP2C8*2 allelic mutant amongst malaria patients in North-Central Nigeria. METHODS: Three hundred and eighty five (385) unrelated study participants were screened for current malaria episodes using routine microscopy and/or rapid diagnostic test strips (RDTs). Chelex extraction method was used for single nucleotide polymorphisms (SNPs) and identification of CYP2C8*2 (805A > T) variant respectively. Wild-type (A) and the defective allele (T) were differentiated with the use of Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The results obtained were further validated with Sanger sequencing of a few samples and thereafter, the genotype data were statistically processed. All alleles obtained were in Hardy Weinberg equilibrium. RESULTS: Out of the 385 participants (45.5% Male and 54.5% Female) genotyped for SNPs, 75 (19.5%) had the autosomal recessive mutant trait. Occurrence of mutant traits was gender and ethnic independent (p > 0.05). Yoruba ethnic group recorded a reduction in proportion of genotypic defective CYP2C8*2 allele (T) (1 in every 8 persons) with a carrier percentage of 13.3% compared with Hausa (26.62%); Igbo (25.37%) and other minority ethnic groups (17.6%). CONCLUSIONS: A remarkable inter-ethnic differences in autosomal recessive CYP2C8*2 allele was observed. By implication, there is a gradual incursion of genetic drift for poor CQ and AQ-Artemisinin metabolizers among the inhabitants.

Acute chloroquine and hydroxychloroquine toxicity: A review for emergency clinicians.

BACKGROUND: Acute chloroquine and hydroxychloroquine toxicity is characterized by a combination of direct cardiovascular effects and electrolyte derangements with resultant dysrhythmias and is associated with significant morbidity and mortality. OBJECTIVE: This review describes acute chloroquine and hydroxychloroquine toxicity, outlines the complex pathophysiologic derangements, and addresses the emergency department (ED) management of this patient population. DISCUSSION: Chloroquine and hydroxychloroquine are aminoquinoline derivatives widely used in the treatment of rheumatologic diseases including systemic lupus erythematosus and rheumatoid arthritis as well as for malaria prophylaxis. In early 2020, anecdotal reports and preliminary data suggested utility of hydroxychloroquine in attenuating viral loads and symptoms in patients with SARS-CoV-2 infection. Aminoquinoline drugs pose unique and significant toxicological risks, both during their intended use as well as in unsupervised settings by laypersons. The therapeutic range for chloroquine is narrow. Acute severe toxicity is associated with 10-30% mortality owing to a combination of direct cardiovascular effects and electrolyte derangements with resultant dysrhythmias. Treatment in the ED is focused on decontamination, stabilization of cardiac dysrhythmias, hemodynamic support, electrolyte correction, and seizure prevention. CONCLUSIONS: An understanding of the pathophysiology of acute chloroquine and hydroxychloroquine toxicity and available emergency treatments can assist emergency clinicians in reducing the immediate morbidity and mortality associated with this disease.

COVID-19 prevention and treatment: A critical analysis of chloroquine and hydroxychloroquine clinical pharmacology.

Nicholas White and coauthors discuss chloroquine and hydroxychloroquine pharmacology in the context of possible treatment of SARS-CoV-2 infection.

Antimalarials as Antivirals for COVID-19: Believe it or Not!

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus responsible for the coronavirus disease -19 (COVID-19). Since December 2019, SARS-CoV-2 has infected millions of people worldwide, leaving hundreds of thousands dead. Chloroquine (CQ) and Hydroxychloroquine (HCQ) are antimalarial medications that have been found to have in vitro efficacy against SARS-CoV-2. Several small prospective studies have shown positive outcomes. However, this result has not been universal, and concerns have been raised regarding the indiscriminate use and potential side effects. The clinicians are conflicted regarding the usage of these medications. Appropriate dose and duration of therapy are unknown. Here, we will discuss the pharmacokinetic and pharmacodynamic properties of CQ and HCQ, as well as review the antiviral properties. The manuscript will also examine the available data from recent clinical and preclinical trials in order to shed light on the apparent inconsistencies.

Chloroquine and hydroxychloroquine in the treatment of malaria and repurposing in treating COVID-19.

Chloroquine (CQ) and Hydroxychloroquine (HCQ) have been commonly used for the treatment and prevention of malaria, and the treatment of autoimmune diseases for several decades. As their new mechanisms of actions are identified in recent years, CQ and HCQ have wider therapeutic applications, one of which is to treat viral infectious diseases. Since the pandemic of the coronavirus disease 2019 (COVID-19), CQ and HCQ have been subjected to a number of in vitro and in vivo tests, and their therapeutic prospects for COVID-19 have been proposed. In this article, the applications and mechanisms of action of CQ and HCQ in their conventional fields of anti-malaria and anti-rheumatism, as well as their repurposing prospects in anti-virus are reviewed. The current trials and future potential of CQ and HCQ in combating COVID-19 are discussed.

Pharmacokinetic Basis of the Hydroxychloroquine Response in COVID-19: Implications for Therapy and Prevention.

BACKGROUND AND OBJECTIVES: Chloroquine/hydroxychloroquine has recently been the subject of intense debate regarding its potential antiviral activity against SARS-Cov-2, the etiologic agent of COVID-19. Some report possible curative effects; others do not. Therefore, the objective of this study was to simulate possible scenarios of response to hydroxychloroquine in COVID-19 patients using mathematical modeling. METHODS: To shed some light on this controversial topic, we simulated hydroxychloroquine-based interventions on virus/host cell dynamics using a basic system of previously published differential equations. Mathematical modeling was implemented using Python programming language v 3.7. RESULTS: According to mathematical modeling, hydroxychloroquine may have an impact on the amplitude of the viral load peak and viral clearance if the drug is administered early enough (i.e., when the virus is still confined within the pharyngeal cavity). The effects of chloroquine/hydroxychloroquine may be fully explained only when also considering the capacity of this drug to increase the death rate of SARS-CoV-2-infected cells, in this case by enhancing the cell-mediated immune response. CONCLUSIONS: These considerations may not only be applied to chloroquine/hydroxychloroquine but may have more general implications for development of anti-COVID-19 combination therapies and prevention strategies through an increased death rate of the infected cells.

Existing highly accumulating lysosomotropic drugs with potential for repurposing to target COVID-19.

Given the speed of viral infection spread, repurposing of existing drugs has been given the highest priority in combating the ongoing COVID-19 pandemic. Only drugs that are already registered or close to registration, and therefore have passed lengthy safety assessments, have a chance to be tested in clinical trials and reach patients quickly enough to help in the current disease outbreak. Here, we have reviewed available evidence and possible ways forward to identify already existing pharmaceuticals displaying modest broad-spectrum antiviral activity which is likely linked to their high accumulation in cells. Several well studied examples indicate that these drugs accumulate in lysosomes, endosomes and biological membranes in general, and thereby interfere with endosomal pathway and intracellular membrane trafficking crucial for viral infection. With the aim to identify other lysosomotropic drugs with possible inherent antiviral activity, we have applied a set of clear physicochemical, pharmacokinetic and molecular criteria on 530 existing drugs. In addition to publicly available data, we have also used our in silico model for the prediction of accumulation in lysosomes and endosomes. By this approach we have identified 36 compounds with possible antiviral effects, also against coronaviruses. For 14 of them evidence of broad-spectrum antiviral activity has already been reported, adding support to the value of this approach. Presented pros and cons, knowledge gaps and methods to identify lysosomotropic antivirals, can help in the evaluation of many drugs currently in clinical trials considered for repurposing to target COVID-19, as well as open doors to finding more potent and safer alternatives.

Synergy of Tumor Microenvironment Remodeling and Autophagy Inhibition to Sensitize Radiation for Bladder Cancer Treatment.

Tumor hypoxia, acidosis, and excessive reactive oxygen species (ROS) were the main characteristics of the bladder tumor microenvironment (TME), and abnormal TME led to autophagy activation, which facilitated cancer cell proliferation. The therapeutic efficacy of autophagy inhibitors might also be impeded by abnormal TME. To address these issues, we proposed a new strategy that utilized manganese dioxide (MnO2) nanoparticles to optimize the abnormal TME and revitalize autophagy inhibitors, and both oxygenation and autophagy inhibition may sensitize the tumor cells to radiation therapy. Methods: By taking advantage of the strong affinity between negatively charged MnO2 and positively charged chloroquine (CQ), the nanoparticles were fabricated by integrating MnO2 and CQ in human serum albumin (HSA)-based nanoplatform (HSA-MnO2-CQ NPs). Results: HSA-MnO2-CQ NPs NPs efficiently generated O2 and increased pH in vitro after reaction with H+/H2O2 and then released the encapsulated CQ in a H+/H2O2 concentration-dependent manner. The NPs restored the autophagy-inhibiting activity of chloroquine in acidic conditions by increasing its intracellular uptake, and markedly blocked hypoxia-induced autophagic flux. In vivo studies showed the NPs improved pharmacokinetic behavior of chloroquine and effectively accumulated in tumor tissues. The NPs exhibited significantly decreased tumor hypoxia areas and increased tumor pH, and had remarkable autophagy inhibition efficacy on bladder tumors. Finally, a significant anti-tumor effect achieved by the enhanced autophagy inhibition and radiation sensitization. Conclusions: HSA-MnO2-CQ NPs synergistically regulated the abnormal TME and inhibited autophagic flux, and effectively sensitized radiation therapy to treat bladder cancers.

Complementary autophagy inhibition and glucose metabolism with rattle-structured polydopamine@mesoporous silica nanoparticles for augmented low-temperature photothermal therapy and in vivo photoacoustic imaging.

Rattle-structured nanoparticles with movable cores, porous shells and hollow interiors have shown great effectiveness in drug delivery and cancer theranostics. Targeting autophagy and glucose have provided alternative strategies for cancer intervention therapy. Herein, rattle-structured polydopamine@mesoporous silica nanoparticles were prepared for in vivo photoacoustic (PA) imaging and augmented low-temperature photothermal therapy (PTT) via complementary autophagy inhibition and glucose metabolism. Methods: The multifunctional rattle-structured nanoparticles were designed with the nanocore of PDA and the nanoshell of hollow mesoporous silica (PDA@hm) via a four-step process. PDA@hm was then loaded with autophagy inhibitor chloroquine (CQ) and conjugated with glucose consumer glucose oxidase (GOx) (PDA@hm@CQ@GOx), forming a corona-like structure nanoparticle. Results: The CQ and GOx were loaded into the cavity and decorated onto the surface of PDA@hm, respectively. The GOx-mediated tumor starvation strategy would directly suppress the expression of HSP70 and HSP90, resulting in an enhanced low-temperature PTT induced by PDA nanocore. In addition, autophagy inhibition by the released CQ made up for the loss of low-temperature PTT and starvation efficiencies by PTT- and starvation-activated autophagy, realizing augmented therapy efficacy. Furthermore, the PDA nanocore in the PDA@hm@CQ@GOx could be also used for PA imaging. Conclusion: Such a "drugs" loaded rattle-structured nanoparticle could be used for augmented low-temperature PTT through complementarily regulating glucose metabolism and inhibiting autophagy and in vivo photoacoustic imaging.