Photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes to promote PD-L1 multivalent binding for effective immune checkpoint blockade therapy

Immune checkpoint blockade(ICB)therapy targeting PD-L1 via monoclonal antibody(m Ab)has shown extensive clinical benefits in the diverse types of advanced malignancies.However,most patients are completely refractory to ICB therapy owing to the PD-L1 recycling mechanism.Herein,we propose photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes(immune checkpoint blockade liposomes;ICB-LPs)to promote PD-L1 multivalent binding for inducing lysosomal degradation of PD-L1 in tumor cells.The ICB-LPs are prepared by formulation of DC_(8,9)PC with photo-polymerized diacetylenic moiety,1,2-dipalmitoylphosphatidylcholine(DPPC)and anti-PD-L1peptide(D-form NYSKPTDRQYHF)-conjugated DSPE-PEG_(2k)(anti-PD-L1-DSPE-PEG_(2k))in a molar ratio of 45:45:10,followed by cross-linking of liposomal bilayer upon UV irradiation.The 10 mol% antiPD-L1-DSPE-PEG_(2k)incorporated ICB-LPs have a nano-sized lipid bilayer structure with an average diameter of 137.7±1.04 nm,showing a high stability in serum condition.Importantly,the ICB-LPs efficiently promote the multivalent binding with PD-L1 on the tumor cell membrane,which are endocytosed with aim to deliver PD-L1 to the lysosomes,wherein the durable PD-L1 degradation is observed for72 h,in contrast to anti PD-L1 m Abs showing the rapid PD-L1 recycling within 9 h.The in vitro coculture experiments with CD8^(+)T cells show that ICB-LPs effectively enhance the T cell-mediated antitumor immune responses against tumor cells by blocking the PD-L1/PD-1 axis.When ICB-LPs are intravenously injected into colon tumor-bearing mice,they efficiently accumulate within the targeted tumor tissues via both passive and active tumor targeting,inducing a potent T cell-mediated antitumor immune response by effective and durable PD-L1 degradation.Collectively,this study demonstrates the superior antitumor efficacy of crosslinked and anti-PD-L1 peptide incorporated liposome formulation that promotes PD-L1 multivalent binding for trafficking of PD-L1 toward the lysosomes instead of the recycling endosomes.

Nanomedicine-mediated immunogenic cell death and its combination with immune checkpoint blockade therapy

Cancer immunotherapies, which train the natural immune system to specifically kill tumor cells while sparing the healthy cells,have helped revolutionize cancer treatments and demonstrated promising clinical therapeutic benefits for decades. However, the therapeutic outcome of immunotherapies, even for the most successful immune checkpoint blockade(ICB) therapy, remains unsatisfactory in the clinical practice, mainly due to the low immunogenicity of solid tumors and its immunosuppressive tumor microenvironment(TME). Notably, several cancer treatment modalities, including chemotherapy, radiotherapy, and phototherapy, have been revealed to evoke tumor immunogenicity and reverse immunosuppressive TME via inducing immunogenic cell death(ICD) of tumor cells, which synergistically sensitized tumors to ICB therapy. Nanomedicines have been extensively applied to augment ICD-inducing treatment modalities and potentiate ICB therapeutic efficacy therapy due to the opportune convergence of immunotherapy and nanotechnology. Here, we discuss the recent advances in nanomedicine-mediated ICD and its combination with ICB therapy.

Combining immune checkpoint blockade with ATP-based immunogenic cell death amplifier for cancer chemo-immunotherapy

Amplifying“eat me signal”during tumor immunogenic cell death(ICD)cascade is crucial for tumor immunotherapy.Inspired by the indispensable role of adenosine triphosphate(ATP,a necessary“eat me signal”for ICD),a versatile ICD amplifier was developed for chemotherapy-sensitized immunotherapy.Doxorubicin(DOX),ATP and ferrous ions(Fe^(2+))were co-assembled into nanosized amplifier(ADO-Fe)throughπ‒πstacking and coordination effect.Meanwhile,phenylboric acid-polyethylene glycol-phenylboric acid(PBA-PEG-PBA)was modified on the surface of ADO-Fe(denoted as PADO-Fe)by the virtue of d-ribose unit of ATP.PADO-Fe could display active targetability against tumor cells via sialic acid/PBA interaction.In acidic microenvironment,PBA-PEG-PBA would dissociate from amplifier.Moreover,high H_(2)O_(2)concentration would induce hydroxyl radical(·OH)and oxygen(O_(2))generation through Fenton reaction by Fe^(2+).DOX and ATP would be released from the amplifier,which could induce ICD effect and“ICD adjuvant”to amplify this process.Together with programmed death ligands 1(PD-L1)checkpoint blockade immunotherapy,PADO-Fe could not only activate immune response against primary tumor,but also strong abscopal effect against distant tumor.Our simple and multifunctional ICD amplifier opens a new window for enhancing ICD effect and immune checkpoint blockade therapy.

Immune checkpoint inhibition mediated with liposomal nanomedicine for cancer therapy

Immune checkpoint blockade(ICB)therapy for cancer has achieved great success both in clinical results and on the market.At the same time,success drives more attention from scientists to improve it.However,only a small portion of patients are responsive to this therapy,and it comes with a unique spectrum of side effects termed immunerelated adverse events(irAEs).The use of nanotechnology could improve ICBs’delivery to the tumor,assist them in penetrating deeper into tumor tissues and alleviate their irAEs.Liposomal nanomedicine has been investigated and used for decades,and is well-recognized as the most successful nano-drug delivery system.The successful combination of ICB with liposomal nanomedicine could help improve the efficacy of ICB therapy.In this review,we highlighted recent studies using liposomal nanomedicine(including new emerging exosomes and their inspired nanovesicles)in associating ICB therapy.

Gene silencing-mediated immune checkpoint blockade for tumor therapy boosted by dendrimer-entrapped gold nanoparticles

Immune checkpoint blockade(ICB) has been regarded as one promising approach for tumor immunotherapy. Here, we report a functional nanoplatform based on generation 5(G5) poly(amidoamine)(PAMAM)dendrimer-entrapped gold nanoparticles(Au DENPs) as a nonviral vector to deliver programmed death-ligand 1(PDL1) small interfering RNA(siPD-L1) for subsequent PD-L1 gene silencing-mediated tumor immunotherapy. In this work,G5 dendrimers with amine termini were partially decorated with methoxy polyethylene glycol(m PEG) on their periphery,entrapped Au NPs within their interiors, and were eventually labeled with fluorescamine. The generated functional Au DENPs possess desired dispersibility in water and colloidal stability, satisfactory cytocompatibility after complexation with siPD-L1, and efficient gene delivery performance. Strikingly, the functional Au DENPs enabled the delivery of siPDL1 to cancer cells to efficiently knock down the PD-L1 protein expression, thus boosting the ICB-based immunotherapy of a xenografted melanoma mouse tumor model with a tumor inhibition efficiency much higher than the PD-L1 antibody.The immune responses were also well demonstrated by downregulation of PD-L1 protein on the tumor cell surface and abundant distribution of CD8+and CD4+T cells in the infiltrating tumor tissue and spleen organ. The developed functional dendrimer-based nanoplatform may be promising to boost ICB-based immunotherapy of other tumor types.

Role of tumor gene mutations in treatment response to immune checkpoint blockades

Early studies shed light on the immune suppression of immune checkpoint molecules in the cancer microenvironment,with later studies applying immune checkpoint blockade(ICB)in treatment of various malignancies.Despite the encouraging efficacy of ICBs in a substantial subset of cancer patients,the treatment response varies.Gene mutations of both tumor cells and immune cells in the tumor microenvironment have recently been identified as potential predictors of the ICB response.Recent developments in gene expression profiling of tumors have allowed identification of a panel of mutated genes that may affect tumor cell response to ICB treatment.In this review,we discuss the association of the ICB response with gene expression and mutation profiles in tumor cells,which it is hoped will help to optimize the clinical application of ICBs in cancer patients.

Liver-directed treatment is associated with improved survival and increased response to immune checkpoint blockade in metastatic uveal melanoma:results from a retrospective multicenter trial

Metastases of uveal melanoma(UM)spread predominantly to the liver.Due to low response rates to systemic therapies,liver-directed therapies(LDT)are commonly used for tumor control.The impact of LDT on the response to systemic treatment is unknown.A total of 182 patients with metastatic UM treated with immune checkpoint blockade(ICB)were included in this analysis.Patients were recruited from prospective skin cancer centers and the German national skin cancer registry(ADOReg)of the German Dermatologic Cooperative Oncology Group(DeCOG).Two cohorts were compared:patients with LDT(cohort A,n=78)versus those without LDT(cohort B,n=104).Data were analyzed for response to treatment,progression-free survival(PFS),and overall survival(OS).The median OS was significantly longer in cohort A than in cohort B(20.1 vs.13.8 months;P=0.0016)and a trend towards improved PFS was observed for cohort A(3.0 vs.2.5 months;P=0.054).The objective response rate to any ICB(16.7%vs.3.8%,P=0.0073)and combined ICB(14.1%vs.4.5%,P=0.017)was more favorable in cohort A.Our data suggest that the combination of LDT with ICB may be associated with a survival benefit and higher treatment response to ICB in patients with metastatic UM.

Angiogenesis and immune checkpoint dual blockade:Opportunities and challenges for hepatocellular carcinoma therapy

The disease burden related to hepatocellular carcinoma(HCC) is increasing. Most HCC patients are diagnosed at the advanced stage and multikinase inhibitors have been the only treatment choice for them. Recently, the approval of immune checkpoint inhibitors(ICIs) has provided a new therapeutic strategy for HCC. It is noteworthy that the positive outcomes of the phase Ⅲ clinical trial IMBrave150 [atezolizumab(anti-programmed cell death ligand 1 antibody) combined with bevacizumab(anti-vascular endothelial growth factor monoclonal antibody)],showed that overall survival and progression-free survival were significantly better with sorafenib. This combination therapy has become the new standard therapy for advanced HCC and has also attracted more attention in the treatment of HCC with anti-angiogenesis-immune combination therapy. Currently, the synergistic antitumor efficacy of this combination has been shown in many preclinical and clinical studies. In this review, we discuss the mechanism and clinical application of anti-angiogenics and immunotherapy in HCC, outline the relevant mechanism and rationality of the combined application of antiangiogenics and ICIs, and point out the existing challenges of the combination therapy.

Decoding cancer's camouflage: epithelial-mesenchymal plasticity in resistance to immune checkpoint blockade

Epithelial-mesenchymal plasticity(EMP)of cancer cells contributes to cancer cell heterogeneity,and it is well established that EMP is a critical determinant of acquired resistance to cancer treatment modalities including radiation therapy,chemotherapy,and targeted therapies.Here,we aimed to explore how EMP contributes to cancer cell camouflage,allowing an ever-changing population of cancer cells to pass under the radar of our immune system and consequently compromise the effect of immune checkpoint blockade therapies.The ultimate clinical benefit of any combination regimen is evidenced by the sum of the drug-induced alterations observed in the variety of cellular populations composing the tumor immune microenvironment.The finely-tuned molecular crosstalk between cancer and immune cells remains to be fully elucidated,particularly for the spectrum of malignant cells along the epithelial to mesenchymal axis.High-dimensional single cell analyses of specimens collected in ongoing clinical studies is becoming a key contributor to our understanding of these interactions.This review will explore to what extent targeting EMP in combination with immune checkpoint inhibition represents a promising therapeutic avenue within the overarching strategy to reactivate a halting cancer-immunity cycle and establish a robust host immune response against cancer cells.Therapeutic strategies currently in clinical development will be discussed.

Effect of microbiome group on immune checkpoint inhibitors in treatment of gastrointestinal tumors

In recent years,immune checkpoint blockade(ICB)therapy has become an important treatment strategy for gastrointestinal tumors,however,it only benefits about 1/3 of patients.Since the microbiome has been shown to play an important role in the human body for a long time,a growing number of studies are focusing on its relationship to ICB therapy in cancer,specifically how intestinal microbes affect the efficacy of immune checkpoint inhibitors(ICIs)therapy in patients.On this basis,probiotic interventions,fecal microbiota transplantation(FMT),dietary interventions,and other methods which improve or maintain the structure of the intestinal flora have attracted widespread attention.This article discusses the four aspects of the microbiome,ICB,combined treatment of gastrointestinal tumors,and regulation of gut microbiome.Particularly,the discussion focuses on the contribution of probiotic intervention in improving the therapeutic effect of ICIs to prolong the survival time of patients and reduce the severity of immune-related adverse effects(irAEs).

Dual-responsive nanovaccine for cytosolic delivery of antigens to boost cellular immune responses and cancer immunotherapy

Cancer vaccine contributing to the success of the treatment and prevention of tumors has attracted a huge attention as a strategy for tumor immunotherapy in recent years.A major challenge of cancer vaccine is to target cytosols of dendritic cells(DCs)in the lymph nodes(LNs)to enhance efficiency of antigen cross-presentation,which elicits high levels of cytotoxic T-lymphocytes to destruct tumor cells.Here,we address this issue by conjugating ovalbumin(OVA)to PEG-PCL using disulfide bond(-ss-),and the degradable pH-responsive polymer-PEI-PCL as delivery carrier.In addition,the mol ratio of PEG-PCL to PEI-PCL in the mixed micelles was tailored to deliver the OVA to LNs.Subsequently,CpG ODN_(1826),a TLR-9 agonist,was further introduced into a mixed micelle of 30nm or less as a unique tumor vaccine.Importantly,the results demonstrated the mixed micelles with 1:1mol of PCL-PEG and PCL-PEI can effectively migrate to distal LNs where antigen were efficiently captured by DCs,meanwhile,OVA was modified to the surface of mixed micelles via disulfide bonds(-ss-)for promotion efficiency of antigen cross-presentation.More surprisingly,combination of tumor vaccine with anti-PD-1,the therapy of ectopic melanoma(B16-OVA)and lung metastasis melanoma(B16-OVA)is excellent therapeutic effect.Taken together,our works offers a novel strategy for the cytosol delivery of antigens to achieve potent cancer immunotherapy.

Immunosuppressive tumor microenvironment in gastric signet-ring cell carcinoma

Gastric signet-ring cell carcinoma(GSRCC)is a subtype of gastric cancer with distinct phenotype and high risk of peritoneal metastasis.Studies have shown that early GSRCC has a good prognosis,while advanced GSRCC is insensitive to radiotherapy,chemotherapy or immune checkpoint blockade therapy.With technological advancement of single-cell RNA sequencing analysis and cytometry by time of flight mass cytometry,more detailed atlas of tumor microenvironment(TME)in GSRCC and its association with prognosis could be investigated extensively.Recently,two single-cell RNA sequencing studies revealed that GSRCC harbored a unique TME,manifested as highly immunosuppressive,leading to high immune escape.The TME of advanced GSRCC was enriched for immunosuppressive factors,including the loss of CXCL13+-cluster of differentiation 8+-Tex cells and declined clonal crosstalk among populations of T and B cells.In addition,GSRCC was mainly infiltrated by follicular B cells.The increased proportion of SRCC was accompanied by a decrease in mucosaassociated lymphoid tissue-derived B cells and a significant increase in follicular B cells,which may be one of the reasons for the poor prognosis of GSRCC.By understanding the relationship between immunosuppressive TME and poor prognosis in GSRCC and the underlying mechanism,more effective immunotherapy strategies and improved treatment outcomes of GSRCC can be anticipated.

Personalized immunotherapy in cancer precision medicine

With the significant advances in cancer genomics using next-generation sequencing technologies,genomic and molecular profilingbased precision medicine is used as a part of routine clinical test for guiding and selecting the most appropriate treatments for individual cancer patients.Although many molecular-targeted therapies for a number of actionable genomic alterations have been developed,the clinical application of such information is still limited to a small proportion of cancer patients.In this review,we summarize the current status of personalized drug selection based on genomic and molecular profiling and highlight the challenges how we can further utilize the individual genomic information.Cancer immunotherapies,including immune checkpoint inhibitors,would be one of the potential approaches to apply the results of genomic sequencing most effectively.Highly cancer-specific antigens derived from somatic mutations,the so-called neoantigens,occurring in individual cancers have been in focus recently.Cancer immunotherapies,which target neoantigens,could lead to a precise treatment for cancer patients,despite the challenge in accurately predicting neoantigens that can induce cytotoxic T cells in individual patients.Precise prediction of neoantigens should accelerate the development of personalized immunotherapy including cancer vaccines and T-cell receptor-engineered T-cell therapy for a broader range of cancer patients.

New developments in immunotherapy for lymphoma

The development of immunotherapies for lymphoma has undergone a revolutionary evolution over the past decades. Since the advent of rituximab as the first successful immunotherapy for B-cell non-Hodgkin lymphoma over two decades ago, a plethora of new immunotherapeutic approaches to treat lymphoma has ensued. Four of the most exciting classes of immunotherapies include:chimeric antigen receptor T-cells, bispecific antibodies, immune checkpoint inhibitors, and vaccines. However, with addition of these novel therapies the appropriate timing of treatment, optimal patient population, duration of therapy, toxicity, and cost must be considered. In this review, we describe the most-promising immunotherapeutic approaches for the treatment of lymphoma in clinical development, specifically focusing on clinical trials performed to date and strategies for improvement.

Programmed albumin nanoparticles regulate immunosuppressive pivot to potentiate checkpoint blockade cancer immunotherapy

The therapeutic efficacy of programmed cell death protein 1/programmed cell death-ligand 1(PD-1/PD-L1)blockade immunotherapy is extremely dampened by complex immunosuppressive mechanisms including regulatory T cells(Treg),M2 macrophages(M2),and prostaglandin E2(PGE2).The pivotal roles of PGE2 have been recognized by directly inactivating CD8+T cells and indirectly inducing Treg and M2.Therefore,PGE2 abolishment through inactivating cyclooxygenase-2(COX-2)could be robust to sensitize tumour toward anti-PD-1/PD-L1 immunotherapy,which has gone into clinical trials.However,exploring this promising strategy in nanomedicine to enhance immunotherapy remains unrevealed.The key challenge to synergistically combine COX-2 inhibition and anti-PD-1/PD-L1 lies in the different pharmacokinetic profiles and the spatial obstacles since PD-1/PD-L1 interaction occurs extracellularly and COX-2 locates intracellularly.Thus,the programmed release nanoparticles(termed as Cele-BMS-NPs)are rationally designed,which are composed of pH-sensitive human serum albumin derivative,BMS-202 compound as PD-1/PD-L1 inhibitor,glutathione(GSH)-activatable prodrug of celecoxib(COX-2 inhibitor).The in vitro experiments demonstrate that this smart Cele-BMS-NPs could extracellularly release BMS-202 under the acidic tumour microenvironment,and the intracellularly release of celecoxib in response to the elevated GSH concentration inside tumour cells.After systemic administration,the intratumoral infiltration of CD8+T cells is significantly enhanced and meanwhile immunosuppressive M2,Treg,and PGE2 are reduced,thereby eliciting the anti-tumour immune responses toward low immunogenic tumours and postsurgical tumour recurrences.

Eliciting pyroptosis to fuel cancer immunotherapy: mechanisms and strategies

Immune checkpoint blockade(ICB)therapy has recently shown promise in treating several malignancies.However,only a limited number of patients respond to this treatment,partially because of the“immune cold”condition of the tumor immune microenvironment.Pyroptosis is a type of gasdermin-mediated programmed cell death that often leads to inflammation and immune responses.Many studies on the mechanism and function of pyroptosis have led to increasing recognition of the role of pyroptosis in malignant progression and immune therapy.Pyroptosis has the potential to alter the tumor immune microenvironment by releasing tumor-associated antigens,damage-associated molecular patterns,and proinflammatory cytokines,thus leading to intratumoral inflammatory responses,stimulation of tumor-specific cytotoxic T cell infiltration,conversion of“cold”to“hot”tumors,and ultimately improving the efficacy of ICB therapy.Some cancer treatments have been shown to restore anticancer immunosurveillance through the induction of pyroptosis.Therapy promoting pyroptosis and ICB therapy may have synergistic effects in cancer treatment.This review summarizes the mechanisms and roles of pyroptosis in the tumor microenvironment and combination treatment strategies.An improved understanding of the roles of pyroptosis in tumorigenesis,immune evasion,and treatment would aid in the development of therapeutic strategies for malignancies.

Mechanisms and strategies to overcome immunotherapy resistance in hepatobiliary malignancies

Unprecedented advances have been achieved in hepatobiliary cancer treatment with immune checkpoint blockade(ICB).However,the efflcacy of ICB in patients with hepatobiliary malignancies is still limited.Resistance to immunotherapies is often orchestrated by complicated tumor-host-microenvironment interactions but could also occur after initial efflcacy,mostly when only partial responses are obtained.Clarification of cancer-resistance mechanisms will be beneficial to provide the rationale for the administration of personalized drugs.Here,we review the factors related to resistance to immune-targeted therapies in hepatobiliary malignancies and discuss the potential strategies for overcoming resistance and future directions of immunotherapy development.

Immunotherapy for recurrent hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is presented frequently in late stages that are not amenable for curative treatment.Even for patients who can undergo resection for curative treatment of HCC,up to 50%recur.For patients who were not exposed to systemic therapy prior to recurrence,recurrence frequently cannot be subjected to curative therapy or local treatments.Such patients have several options of immunotherapy(IO).This includes programmed cell death protein 1(PD-1)and cytotoxic T-lymphocyte associated protein 4 treatment,combination of PD-1 and vascular endothelial growth factor inhibitor or single agent PD-1 therapy when all other options are deemed inappropriate.There are also investigational therapies in this area that explore either PD-1 and tyrosine kinase inhibitors or a novel agent in addition to PD-1 with vascular endothelial growth factor inhibitors.This minireview explored IO options for patients with recurrent HCC who were not exposed to systemic therapy at the initial diagnosis.We also discussed potential IO options for patients with recurrent HCC who were exposed to first-line therapy with curative intent at diagnosis.

Why natural killer cells in triple negative breast cancer?

The triple-negative subtype of breast cancer(TNBC)has the bleakest prognosis,owing to its lack of either hormone receptor as well as human epidermal growth factor receptor 2.Henceforth,immunotherapy has emerged as the front-runner for TNBC treatment,which avoids potentially damaging chemotherapeutics.However,despite its documented association with aggressive side effects and developed resistance,immune checkpoint blockade continues to dominate the TNBC immunotherapy scene.These immune checkpoint blockade drawbacks necessitate the exploration of other immunotherapeutic methods that would expand options for TNBC patients.One such method is the exploitation and recruitment of natural killer cells,which by harnessing the innate rather than adaptive immune system could potentially circumvent the downsides of immune checkpoint blockade.In this review,the authors will elucidate the advantageousness of natural killer cell-based immuno-oncology in TNBC as well as demonstrate the need to more extensively research such therapies in the future.

Liposome-coated CaO_(2)nanoblockers for enhanced checkpoint blockade therapy by inhibiting PD-L1 de novo biosynthesis

The blocking of the immune checkpoint pathway with antibodies,especially targeting to programmed death-1/programmed death ligand-1(PD-1/PD-L1)pathway,was currently a widely used treatment strategy in clinical practice.However,the shortcomings of PD-L1 antibodies were constantly exposed with the deepening of its research and their therapeutic effect was limited by the translocation and redistribution of intracellular PD-L1.Herein,we proposed to improve immune checkpoint blockade therapy by using liposomes-coated CaO_(2)(CaO_(2)@Lipo)nanoparticles to inhibit the de novo biosynthesis of PD-L1.CaO_(2)@Lipo would produce oxygen and reduce hypoxia-inducible factor-1α(HIF-1α)level,which then downregulated the expression of PD-L1.Our in vitro and in vivo results have confirmed CaO_(2)@Lipo promoted the degradation of HIF-1αand then downregulated the expression of PD-L1 in cancer cells for avoiding immune escape.Furthermore,to mimicking the clinical protocol of anti-PD-L1 antibodies+chemo-drugs,CaO_(2)@Lipo was combined with doxorubicin(DOX)to investigate the tumor inhibition efficiency.We found CaO_(2)@Lipo enhanced DOX-induced immunogenic cell death(ICD)effect,which then promoted the infiltration of T cells,strengthened the blocking effect,thus provided an effective means to overcome the traditional immune checkpoint blockade treatment.