Bacteria-Mediated Synergistic Cancer Therapy:Small Microbiome Has a Big Hope

The use of bacteria to specifically migrate to cancerous tissue and elicit an antitumor immune response provides a promising platform against cancer with significantly high potency.With dozens of clinical trials underway,some researchers hold the following views:“humans are nearing the first commercial live bacteria therapeutic.”However,the facultative anaerobe Salmonella typhimurium VNP20009,which is particularly safe and shows anticancer effects in preclinical studies,had failed in a phase I clinical trial due to low tumor regression and undesired dose-dependent side effects.This is almost certain to disappoint people’s inflated expectations,but it is noted that recent stateof-the-art research has turned attention to bacteria-mediated synergistic cancer therapy(BMSCT).In this review,the foundation of bacteria-mediated bio-therapy is outlined.Then,we summarize the potential benefits and challenges of bacterial bio-therapy in combination with different traditional anticancer therapeutic modalities(chemotherapy,photothermal therapy,reactive oxygen and nitrogen species therapy,immunotherapy,or prodrug-activating therapy)in the past 5 years.Next,we discuss multiple administration routes of BMSCT,highlighting potentiated antitumor responses and avoidance of potential side effects.Finally,we envision the opportunities and challenges for BMSCT development,with the purpose of inspiring medicinal scientists to widely utilize the microbiome approach in patient populations.

Intestinal OCTN2-and MCT1-targeted drug delivery to improve oral bioavailability

Various drug transporters are widely expressed throughout the intestine and play important roles in absorbing nutrients and drugs,thus providing high quality targets for the design of prodrugs or nanoparticles to facilitate oral drug delivery.In particular,intestinal carnitine/organic cation transporter 2(OCTN2)and mono-carboxylate transporter protein 1(MCT1)possess high transport capacities and complementary distributions.Therefore,we outline recent developments in transporter-targeted oral drug delivery with regard to the OCTN2 and MCT1 proteins in this review.First,basic information of the two transporters is reviewed,including their topological structures,characteristics and functions,expression and key features of their substrates.Furthermore,progress in transporter-targeting prodrugs and nanoparticles to increase oral drug delivery is discussed,including improvements in the oral absorption of anti-inflammatory drugs,antiepileptic drugs and anticancer drugs.Finally,the potential of a dual transporter-targeting strategy is discussed.

Co-amorphous solid dispersion systems of lacidipine-spironolactone with improved dissolution rate and enhanced physical stability

Co-amorphous solid dispersion(C-ASD)systems have attracted great attention to improve the solubility of poorly soluble drugs,but the selection of an appropriate stabilizer to stabilize amorphous forms is still a huge challenge.Herein,C-ASD system of two clinical combined used drugs(lacidipine(LCDP)and spironolactone(SPL))as stabilizers to each other,was prepared by solvent evaporation method.The effects of variation in molar ratio of LCDP and SPL(3:1,1:1,1:3,1:6,and 1:9)on the drug release characteristics were explored.Polarized light microscopy(PLM),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA)were employed to evaluate the solid states.Prepared C-ASDs were further studied for their stability under the high humidity(RH 92.5%).Further analysis of C-ASDs via Fourier-transform infrared spectroscopy(FTIR)and Raman spectroscopy confirmed that hydrogen bond interactions between the two drugs played a significant role in maintaining the stability of the C-ASDs systems.Moreover,molecular dynamic(MD)simulations provided a clear insight into the stability mechanism at the molecular level.This study demonstrated the novel drug-drug C-ASDs systems is a promising formulation strategy for improved dissolution rate and enhanced physical stability of poorly soluble drugs.

A computer-aided chem-photodynamic drugs self-delivery system for synergistically enhanced cancer therapy

The therapeutic strategy that gives consideration to the combination of photodynamic therapy and chemotherapy,has emerged as a potential development of effective anti-cancer medicine.Nevertheless,co-delivery of photosensitizers(PSs)and chemotherapeutic drugs in traditional carriers still remains great limitations due to low drug loadings and poor biocompatibility.Herein,we have utilized a computer-aided strategy to achieve a desired carrier-free self-delivery of pyropheophorbide a(PPa,a common PS)and podophyllotoxin(PPT,a classical chemotherapeutic drug)for synergistic cancer therapy.First,the computational simulation method identified the similar molecular sizes and rigid molecular structures between two drugs molecules.Based on the molecular docking,the intermolecular interactions were found to includeπ-πstackings,hydrophobic interactions and hydrogen bonds.Next,both drugs could co-assemble into nanoparticles(NPs)via one-step nanoprecipitation method.The various spectral experiments(UV,IR and FL)were conducted to evaluate the formation mechanism of spherical NPs.Moreover,in vitro and in vivo experiments systematically demonstrated that PPT/PPa NPs not only showed better cellular uptake efficiency,stronger cytotoxicity and higher accumulation in tumor sites,but also exhibited synergistic antitumor effect in female BALB/C bearing-4T1 tumor mice.Such a computer-aided design strategy of chem-photodynamic drugs self-delivery systems pave the way for efficient synergistic cancer therapy.

Recent advances in bacteriophage-based therapeutics:Insight into the post-antibiotic era

Antibiotic resistance is one of the biggest threats to global health, as it can make the treatment of bacterial infections in humans difficult owing to their high incidence rate, mortality, and treatment costs. Bacteriophage, which constitutes a type of virus that can kill bacteria, is a promising alternative strategy against antibiotic-resistant bacterial infections. Although bacteriophage therapy was first used nearly a century ago, its development came to a standstill after introducing the antibiotics. Nowadays, with the rise in antibiotic resistance, bacteriophage therapy is in the spotlight again.As bacteriophage therapy is safe and has significant anti-bacterial activity, some specific types of bacteriophages(such as bacteriophage phi X174 and Pyo bacteriophage complex liquid) entered into phase Ⅲ clinical trials. Herein, we review the key points of the antibiotic resistance crisis and illustrate the factors that support the renewal of bacteriophage applications. By summarizing recent state-of-the-art studies and clinical data on bacteriophage treatment, we introduced(i) the pharmacological mechanisms and advantages of antibacterial bacteriophages,(ii) bacteriophage preparations with clinical potential and bacteriophage-derived anti-bacterial treatment strategies, and(iii) bacteriophage therapeutics aimed at multiple infection types and infection-induced cancer treatments. Finally, we highlighted the challenges and critical perspectives of bacteriophage therapy for future clinical development.

Pure redox-sensitive paclitaxelemaleimide prodrug nanoparticles: Endogenous albumininduced size switching and improved antitumor efficiency

A commercial albumin-bound paclitaxel nano-formulation has been considered a gold standard against breast cancer.However,its application still restricted unfavorable pharmacokinetics and the immunogenicity of exogenous albumin carrier.Herein,we report an albumin-bound tumor redoxresponsive paclitaxel prodrugs nano-delivery strategy.Using diverse linkages(thioether bond and disulfide bond),paclitaxel(PTX)was conjugated with an albumin-binding maleimide(MAL)functional group.These pure PTX prodrugs could self-assemble to form uniform and spherical nanoparticles(NPs)in aqueous solution without any excipients.By immediately binding to blood circulating albumin after intravenous administration,NPs are rapidly disintegrated into small prodrug/albumin nanoaggregates in vivo,facilitating PTX prodrugs accumulation in the tumor region via albumin receptormediated active targeting.The tumor redox dual-responsive drug release property of prodrugs improves the selectivity of cytotoxicity between normal and cancer cells.Moreover,disulfide bond-containing prodrug/albumin nanoaggregates exhibit long circulation time and superior antitumor efficacy in vivo.This simple and facile strategy integrates the biomimetic characteristic of albumin,tumor redox-responsive on-demand drug release,and provides new opportunities for the development of the high-efficiency antitumor nanomedicines.

Emerging systemic delivery strategies of oncolytic viruses:A key step toward cancer immunotherapy

Oncolytic virotherapy(OVT)is a novel type of immunotherapy that induces anti-tumor responses through selective self-replication within cancer cells and oncolytic virus(OV)-mediated immunostimulation.Notably,talimogene laherparepvec(T-Vec)developed by the Amgen company in 2015,is the first FDA-approved OV product to be administered via intratumoral injection and has been the most successful OVT treatment.However,the systemic administration of OVs still faces huge challenges,including in vivo pre-existing neutralizing antibodies and poor targeting delivery efficacy.Recently,state-of-the-art progress has been made in the development of systemic delivery of OVs,which demonstrates a promising step toward broadening the scope of cancer immunotherapy and improving the clinical efficacy of OV delivery.Herein,this review describes the general characteristics of OVs,focusing on the action mechanisms of OVs as well as the advantages and disadvantages of OVT.The emerging multiple systemic administration approaches of OVs are summarized in the past five years.In addition,the combination treatments between OVT and traditional therapies(chemotherapy,thermotherapy,immunotherapy,and radiotherapy,etc.)are highlighted.Last but not least,the future prospects and challenges of OVT are also discussed,with the aim of facilitating medical researchers to extensively apply the OVT in the cancer therapy.

Structurally defined tandem-responsive nanoassemblies composed of dipeptide-based photosensitive derivatives and hypoxia-activated camptothecin prodrugs against primary and metastatic breast tumors

Substantial progress in the use of chemo-photodynamic nano-drug delivery systems(nanoDDS) for the treatment of the malignant breast cancer has been achieved. The inability to customize precise nanostructures, however, has limited the therapeutic efficacy of the prepared nano-DDS to date. Here,we report a structurally defined tandem-responsive chemo-photosensitive co-nanoassembly to eliminate primary breast tumor and prevent lung metastasis. This both-in-one co-nanoassembly is prepared by assembling a biocompatible photosensitive derivative(pheophorbide-diphenylalanine peptide, PPADA) with a hypoxia-activated camptothecin(CPT) prodrug [(4-nitrophenyl) formate camptothecin, NCPT]. According to computational simulations, the co-assembly nanostructure is not the classical core-shell type, but consists of many small microphase regions. Upon exposure to a 660 nm laser,PPA-DA induce high levels of ROS production to effectively achieve the apoptosis of normoxic cancer cells. Subsequently, the hypoxia-activated N-CPT and CPT spatially penetrate deep into the hypoxic region of the tumor and suppress hypoxia-induced tumor metastasis. Benefiting from the rational design of the chemo-photodynamic both-in-one nano-DDS, these nanomedicines exhibit a promising potential in the inhibition of difficult-to-treat breast tumor metastasis in patients with breast cancer.

A boronic acid conjugation integrates antitumor drugs into albumin-binding prodrugs-based nanoparticles with robust efficiency for cancer therapy

Despite great therapeutic effect of Abraxane®,complex preparation technology and unfavorable pharmacokinetics still restricted the clinical application of albumin-based paclitaxel(PTX)nanoparticles(NPs).Herein,we reported that an albumin-binding prodrug,phenylboronic acid-conjugated PTX(P-PTX),can form the uniform NPs with the diameters around 100 nm with the help of albumin via simple one-step nano-precipitation method.The albumin-based nanomedicines were stabilized by the integration of a single boronic acid with PTX due to the increased affinity based on multiple intermolecular interactions.We found that albumin-based P-PTX NPs exhibited superior colloidal stability over albumin-based PTX NPs through one-step nanoprecipitation approach,achieving longer in vivo circulation time and higher concentration in tumor than those of the marketed Abraxane®.Furthermore,the albumin-based P-PTX NPs with great stability and enhanced intratumoral enrichment,increased the maximum tolerated dose of PTX,remarkably suppressed the growth of breast tumor and lung metastasis,prolonged survival of melanoma tumors-bearing mice.Such a convenient and effective system gains an insight into the impact of phenylboronic acid group on the albumin-based PTX NPs,provides potent strategy for the rational design of albumin-based antitumor nanomedicines.

Emerging nanomedicine and prodrug delivery strategies for the treatment of inflammatory bowel disease

Inflammatory bowel disease(IBD)is a chronic and recurrent disease of the gastrointestinal tract,mainly including Crohn's disease(CD)and ulcerative colitis(UC).However,current approaches against IBD do not precisely deliver drugs to the inflammatory site,which leads to life-long medication and serious side effects that can adversely impact patients’adherence.It is necessary to construct optimal drug delivery systems(DDSs)that can target drugs to the region of inflammation,thereby improve therapeutic efficacy and reduce side effects.With the burgeoning development of nanotechnology-based nanomedicines(NMs)and prodrug strategy,remarkable progresses in the treatment of IBD have been made in recent years.Herein,the latest advances are outlined at the intersection of IBD treatment and nanotherapeutics as well as prodrug therapy.First,the pathophysiological microenvironment of inflammatory sites of IBD is introduced in order to rationally design potential NMs and prodrugs.Second,the necessity of NMs for the IBD therapy is elaborated,and the representative nanotherapeutics via passive targeted and active targeted NMs developed to treat the IBD are overviewed.Furthermore,the emerging prodrug-based therapeutics are summarized,including 5-aminosalicylic acid-,amino acid-,and carbohydrate-conjugated prodrugs.Finally,the design considerations and perspectives of these NMs and prodrugs-driven IBD therapeutics in the clinical translation are spotlighted.