An Overview of Quality Management of Therapeutic Vaccines in Clinical Trials in China

Objective To provide suggestions and a reference for improving the quality management system of clinical trials of therapeutic vaccines and promoting the development of therapeutic vaccines in China.Methods Literature research,case study and comparative study were used to analyze the quality management system of clinical trials of therapeutic vaccines.Results and Conclusion From the perspective of the sponsor,investigators and the thirdparty technical service company,the problems such as the low efficiency of clinical trial sample preparation and the lax implementation of the protocol by hospital departments in the quality management of clinical trials of therapeutic vaccines in China were found.Then,the optimization plan for the quality management of clinical trials of therapeutic vaccines is proposed,including optimizing the preparation process of therapeutic vaccines and strengthening the training of hospital department personnel.

HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

BACKGROUND: As the host immunity is diminished in patients with chronic hepatitis B (CHB), different approaches have been used to up-regulate their immune responses to produce therapeutic effects. But, cytokines, growth factors and polyclonal immune modulators could not exhibit sufficient therapeutic effects in these patients. Immune therapy with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients. DATA SOURCE: Preclinical and clinical studies on immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed. RESULTS: HBsAg-based prophylactic vaccine was used as an immune therapeutic agent in CHB patients; however, monotherapy with HBsAg-based immune therapy could not lead to sustained control of HBV replication and/or liver damages. HBsAg-based vaccine was used as a combination therapy with cytokines, growth factors, and antiviral drugs. HBsAg-based vaccine was also used for cell-based therapy. However, satisfactory therapeutic effects of HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is endowed with antiviral and liver protecting capacities in CHB patients. Recent data concentrate on the clinical use of combined HBsAg- and HBcAg-based vaccines in CHB patients.CONCLUSION: Antigen-based immune therapy with HBV- related antigens may be an alternative method for the treatment of CHB patients but proper designs of antigens, types of adjuvants, dose of vaccinations, and routes of administration need further analyses for the development of an effective regimen of immune therapy against HBV.

Immunotherapy and therapeutic vaccines in prostate cancer： an update on current strategies and clinical implications

In recent years, immunotherapy has emerged as a viable and attractive strategy for the treatment of prostate cancer. While there are multiple ways to target the immune system, therapeutic cancer vaccines and immune checkpoint inhibitors have been most successful in late-stage clinical trials. The landmark Food and Drug Administration approval of sipuleuceI-T for asymptomatic or minimally symptomatic metastatic prostate cancer set the stage for ongoing phase III trials with the cancer vaccine PSA-TRICOM and the immune checkpoint inhibitor ipilimumab. A common feature of these immune-based therapies is the appearance of improved overall survival without short-term changes in disease progression. This class effect appears to be due to modulation of tumor growth rate kinetics, in which the activated immune system exerts constant immunologic pressure that slows net tumor growth. Emerging data suggest that the ideal population for clinical trials of cancer vaccines is patients with lower tumor volume and less aggressive disease. Combination strategies that combine immunotherapy with standard therapies have been shown to augment both immune response and clinical benefit.

Current progress in the development of prophylactic and therapeutic vaccines

Vaccines are essential public health tools and play an important role in reducing the burden of infectious diseases in the population.Emerging infectious diseases and outbreaks pose new challenges for vaccine development,requiring the rapid design and production of safe and effective vaccines against diseases with limited resources.Here,we focus on the development of vaccines in broad fields ranging from conventional prophylactic vaccines against infectious diseases to therapeutic vaccines against chronic diseases and cancer,providing a comprehensive overview of recent advances in eight different vaccine forms(live attenuated vaccines,inactivated vaccines,polysaccharide and polysaccharide conjugate vaccines,recombinant subunit vaccines,virus-like particle and nanoparticle vaccines,polypeptide vaccines,DNA vaccines,and m RNA vaccines)and the therapeutic vaccines against five solid tumors(lung cancer,breast cancer,colorectal cancer,liver cancer and gastric cancer),three infectious diseases(human immunodeficiency virus,hepatitis B virus and human papillomavirus-induced diseases)and three common chronic diseases(hypertension,diabetes mellitus and dyslipidemia).We aim to provide new insights into vaccine technologies,platforms,applications and understanding of potential next-generation preventive and therapeutic vaccine technologies,paving the way for the vaccines design in the future.

Development of therapeutic cancer vaccines using nanomicellar preparations

Cancer treatment is a multifaceted challenge,and therapeutic vaccines have emerged as a promising approach.The micellar preparation efficiently encapsulates antigen polypeptides and enhances antigen presentation through the major histocompatibility class I pathway,promoting cytotoxic T lymphocyte immune responses.Moreover,it enables codelivery of both antigen and adjuvant to the same target antigen-presenting cells.Combining themicellar vaccine with traditional cancer treatments(such as chemotherapy,radiotherapy,and surgery)has demonstrated improved efficacy in murine tumor models.Overall,the polyethylene glycol-phosphatidylethanolamine micelle-based vaccine presents a promising platformfor cancer therapeutic vaccines.By leveraging the strengths of various treatmentmodalities,this innovative vaccine approach holds the potential to revolutionize cancer therapy and bring new possibilities for cancer patients.

Toward a new era of hepatitis B virus therapeutics:The pursuit of a functional cure

Hepatitis B virus(HBV)infection,although preventable by vaccination,remains a global health problem and a major cause of chronic liver disease.Although current treatment strategies suppress viral replication very efficiently,the optimal endpoint of hepatitis B surface antigen(HBsAg)clearance is rarely achieved.Moreover,the thorny problems of persistent chromatin-like covalently closed circular DNA and the presence of integrated HBV DNA in the host genome are ignored.Therefore,the scientific community has focused on developing innovative therapeutic approaches to achieve a functional cure of HBV,defined as undetectable HBV DNA and HBsAg loss over a limited treatment period.A deeper understanding of the HBV life cycle has led to the introduction of novel direct-acting antivirals that exert their function through multiple mechanisms,including inhibition of viral entry,transcriptional silencing,epigenetic manipulation,interference with capsid assembly,and disruption of HBsAg release.In parallel,another category of new drugs aims to restore dysregulated immune function in chronic hepatitis B accompanied by lethargic cellular and humoral responses.Stimulation of innate immunity by pattern-recognition receptor agonists leads to upregulation of antiviral cytokine expression and appears to contribute to HBV containment.Immune checkpoint inhibitors and adoptive transfer of genetically engineered T cells are breakthrough technologies currently being explored that may elicit potent HBV-specific T-cell responses.In addition,several clinical trials are attempting to clarify the role of therapeutic vaccination in this setting.Ultimately,it is increasingly recognized that elimination of HBV requires a treatment regimen based on a combination of multiple drugs.This review describes the rationale for progressive therapeutic interventions and discusses the latest findings in the field of HBV therapeutics.

Nucleic acid vaccines: A taboo broken and prospect for a hepatitis B virus cure

Although a prophylactic vaccine is available,hepatitis B virus(HBV)remains a major cause of liver-related morbidity and mortality.Current treatment options are improving clinical outcomes in chronic hepatitis B;however,true functional cure is currently the exception rather than the rule.Nucleic acid vaccines are among the emerging immunotherapies that aim to restore weakened immune function in chronically infected hosts.DNA vaccines in particular have shown promising results in vivo by reducing viral replication,breaking immune tolerance in a sustained manner,or even decimating the intranuclear covalently closed circular DNA reservoir,the hallmark of HBV treatment.Although DNA vaccines encoding surface antigens administered by conventional injection elicit HBVspecific T cell responses in humans,initial clinical trials failed to demonstrate additional therapeutic benefit when administered with nucleos(t)ide analogs.In an attempt to improve vaccine immunogenicity,several techniques have been used,including codon/promoter optimization,coadministration of cytokine adjuvants,plasmids engineered to express multiple HBV epitopes,or combinations with other immunomodulators.DNA vaccine delivery by electroporation is among the most efficient strategies to enhance the production of plasmid-derived antigens to stimulate a potent cellular and humoral anti-HBV response.Preliminary results suggest that DNA vaccination via electroporation efficiently invigorates both arms of adaptive immunity and suppresses serum HBV DNA.In contrast,the study of mRNA-based vaccines is limited to a few in vitro experiments in this area.Further studies are needed to clarify the prospects of nucleic acid vaccines for HBV cure.

Bidirectional crosstalk between therapeutic cancer vaccines and the tumor microenvironment:Beyond tumor antigens

Immunotherapy has rejuvenated cancer therapy,especially after anti-PD-(L)1 came onto the scene.Among the many therapeutic options,therapeutic cancer vaccines are one of the most essential players.Although great progress has been made in research on tumor antigen vaccines,few phase III trials have shown clinical benefits.One of the reasons lies in obstruction from the tumor microenvironment(TME).Meanwhile,the therapeutic cancer vaccine reshapes the TME in an ambivalent way,leading to immune stimulation or immune escape.In this review,we summarize recent progress on the interaction between therapeutic cancer vaccines and the TME.With respect to vaccine resistance,innate immunosuppressive TME components and acquired resistance caused by vaccination are both involved.Understanding the underlying mechanism of this crosstalk provides insight into the treatment of cancer by directly targeting the TME or synergizing with other therapeutics.

Development of mRNA vaccines and their prophylactic and therapeutic applications

Nucleic acid vaccines have attracted enormous attention for resolving the limitations of conventional vaccines using live attenuated viruses. Because nucleic acid vaccines can be produced rapidly in response to the emergence of new virus strains, they are more appropriate for the control of urgent epidemic and pandemic issues. In particular, messenger RNA （mRNA） vaccines have evolved as a new type of nucleic acid vaccines in accordance with their superior protein expression and a lack of mutagenesis as compared with DNA vaccines. Using mRNA vaccines, large amounts of target proteins can be expressed in immune cells for efficient immunization. For instance, antigen-specific vaccination is a feasible option involving the expression of specific antigens in antigen-presenting cells. Immunological reactions are modulated by expressing several proteins associated with stimulation or maturation of immune cells. In addition, mRNA vaccines can stimulate innate immunity through specific recognition by pattern recognition receptors. On the basis of these remarkable properties, mRNA vaccines have been used for prophylactic and therapeutic applications. This review highlights the role of mRNA vaccines as prophylactic vaccines for prevention of future infections and as therapeutic vaccines for cancer immunotherapy. In addition to the conventional type of mRNA vaccines, RNA replicons （self-amplifying mRNA vaccines） will be described.

Construction and characterization of calreticulin-HBsAg fusion gene recombinant adenovirus expression vector

AIM: To generate recombinant adenoviral vector con-taining calreticulin (CRT)-hepatitis B surface antigen (HBsAg) fusion gene for developing a safe, effective and HBsAg-specific therapeutic vaccine.METHODS: CRT and HBsAg gene were fused using polymerase chain reaction (PCR), endonuclease diges-tion and ligation methods. The fusion gene was cloned into pENTR/D-TOPO transfer vector after the base pairs of DNA (CACC) sequence was added to the 5′ end. Adenoviral expression vector containing CRT-HBsAg fusion gene was constructed by homologous recombinan-tion. The human embryo kidney (HEK) 293A cells were transfected with linearized DNA plasmid of the recombi-nant adenoviral vector to package and amplify recombi-nant adenovirus. The recombinant adenovirus titer was characterized using the end-dilution assay. The expres-sion of the CRT/HBsAg fusion protein in Ad-CRT/HBsAg infected 293A cells was detected by Western blotting.RESULTS: The CRT-HBsAg fusion gene was char-acterized by PCR and sequencing and its length and sequence were confirmed to be accurate. The CRT-HB-sAg fusion gene recombinant pENTR/D-TOPO transfer vector was constructed. The recombinant adenoviral vector, Ad-CRT/HBsAg, was generated successfully. The titer of Ad-CRT/HBsAg was characterized as 3.9 × 1011 pfu/mL. The CRT-HBsAg fusion protein was ex-pressed by HEK 293A cells correctly. CONCLUSION: CRT/HBsAg fusion gene recombinant replication-defective adenovirus expression vector is constructed successfully and this study has provided an experimental basis for further studies of Hepatitis B vi-rus gene therapy.

Therapeutic dendritic cell vaccines engineered with antigen-biomineralized Bi_(2)S_(3) nanoparticles for personalized tumor radioimmunotherapy

Therapeutic vaccines,an exciting development in cancer immunotherapy,share the goal of priming of personalized antigen-specific T-cell response by precise antigen presentation of dendritic cells(DCs),but major obstacles include insufficient antigen loading and off-target to DCs remain to their success.Here,we developed an imageable therapeutic vaccine with whole-antigen loading and target delivery constructed by ovalbumin(OVA)-biomineralized Bi_(2)S_(3) nanoparticles-pulsed DCs.Relying on the strong X-ray absorption and fluorescence labeling performance of Bi_(2)S_(3)@OVA nanoparticles,the in vivo spatiotemporal fate of the vaccine(Bi_(2)S_(3)@OVA@DC)can be noninvasively monitored by computed tomography and near-infrared fluorescence imaging in real time.The Bi_(2)S_(3)@OVA@DC can rapidly and durably accumulate in draining lymph nodes and thus trigger stronger T-cell responses compared to OVA-pulsed DCs.Meanwhile,Bi_(2)S_(3)@OVA@DC can further achieve in vivo antitumor effects against OVA-expressing B16F10 melanoma when combined with fractionated radiotherapy,resulting from the upregulation of cytotoxic CD8^(+)T cells and restraint of regulatory T cells in the tumor microenvironment,and the systemical secretion of OVA-specific IgG1/IgG2α antibody.Overall,we successfully fabricated an engineered DC vaccine featured in high whole-antigen loading capacity that can be precisely delivered to the lymphatic system for visualization,serving as a powerful therapeutic platform for cancer radioimmunotherapy.

Construction of Recombinant Modified Vaccinia Ankara(MVA) Expressing Hepatitis B Virus Surface Antigen

The T lymphocyte response has been shown to be the determinant in the clearance of many viral infections. Hence, therapeutic vaccine candidates against HBV are designed to enhance this response of the immune system. Vaccinia virus vector-based vaccines have been proposed as excellent candidates to elicit long-term and strong T lymphocyte mediated immune responses. In this study, the recombinant MVA expressing HBV surface antigen has been constructed, which can elicit a potent T cell mediated response. The ELISA results for the surface protein in the medium of the recombinant MVA, strongly indicate that the recombinant virus has been successfully obtained.

Overcoming HBV immune tolerance to eliminate HBsAg-positive hepatocytes via pre-administration of GM-CSF as a novel adjuvant for a hepatitis B vaccine in HBV transgenic mice

Granulocyte-macrophage colony-stimulating factor （GM-CSF） is known to be a potential vaccine adjuvant despite contradictory results from animal and human studies. The discrepancies may be due to the different doses and regimens of GM-CSF that were used, given that either mature or immature dendritic cells （DCs） could be induced under different conditions. To test the hypothesis that GM-CSF can be used as a novel adjuvant for a hepatitis B virus （HBV） therapeutic vaccine, we administered GM-CSF once per day for three days prior to vaccination with recombinant HBV vaccine （rHBVvac） in mice. We observed greater DC maturation in these pre-treated animals at day 3 as compared to day 1 or day 2 of daily GM-CSF administration. This strategy was further investigated for its ability to break the immune tolerance established in hepatitis B surface antigen-transgenic （HBsAg-Tg） animals. We found that the levels of induced anti-HBsAg antibodies were significantly higher in animals following three days of GM-CSF pre-treatment before rHBV vaccination after the third immunization. In addition to the increase in anti-HBsAg antibody levels, cell-mediated anti-HBsAg responses, including delayed-type hypersensitivity, T-cell proliferation, interferon-y production, and cytotoxic T lymphocytes, were dramatically enhanced in the three-day GM-CSF pre-treated group. After adoptive transfers of CD8＋ T cells from immunized animals, antigen-specific CD8＋ T cells were observed in the livers of recipient HBsAg-Tg animals. Moreover, the three-day pre-treatments with GM-CSF prior to rHBVvac vaccination could significantly eliminate HBsAg-positive hepatocytes, suggesting beneficial therapeutic effects. Therefore, this protocol utilizing GM-CSF as an adjuvant in combination with the rHBVvac vaccine has the potential to become a novel immunotherapy for chronic hepatitis B patients.

Novel exosome-targeted T-cell-based vaccine counteracts T-cell anergy and converts CTL exhaustion in chronic infection via CD40L signaling through the mTORC1 pathway

CD8＋ cytotoxic T lymphocyte （CTL） exhaustion is a chief issue for ineffective virus elimination in chronic infectious diseases. We generated novel ovalbumin （OVA）-specific OVA-Texo and HIV-specific Gag-Texo vaccines inducing therapeutic immunity. To assess their therapeutic effect in chronic infection, we developed a new chronic infection model by i.v. infecting C57BL/6 mice with the OVA-expressing adenovirus AdVova. During chronic AdVova infection, mouse CTLs were found to express the inhibitory molecules programmed cell-death protein-1 （PD-1） and lymphocyte-activation gene-3 （LAG-3） and to be functionally exhausted, showing a significant deficiency in T-cell proliferation, IFN-7 production and cytolytic effects. Naive CD8＋ T cells upregulated inhibitory PD-ligand 1 （PD-L1）, B- and T-lymphocyte attenuator and T-cell anergy-associated molecules （Grail and Itch） while down-regulating the proliferative response upon stimulation in mice with chronic infection. Remarkably, the OVA-Texo vaccine counteracted T-cell anergy and converted CTL exhaustion. The latter was associated with （i） the upregulation of a marker for CTL functionality, diacetylated histone-H3 （diAcH3）, （ii） a fourfold increase in CTLs, occurring independent of host DCs or CD4＋ T cells, and （iii） the restoration of CTL IFN-7 production and cytotoxicity. In vivo OVA-Texo-stimulated CTLs upregulated the activities of the mTORC1 pathway-related molecules Akt, S6, elF4E and T-bet, and treatment of the CTLs with an mTORC1 inhibitor, rapamycin, significantly reduced the OVA-Texo- induced increase in CTLs. Interestingly, OVA-Texo-mediated CD40L signaling played a critical role in the observed immunological effects. Importantly, the Gag-Texo vaccine induced Gag-specific therapeutic immunity in chronic infection. Therefore, this study should have a serious impact on the development of new therapeutic vaccines for human immunodeficiency virus （HIV-1） infection.

Albumin fusion with granulocyte-macrophage colony-stimulating factor acts as an immunotherapy against chronic tuberculosis

A long duration of treatment and emerging drug resistance pose significant challenges for global tuberculosis(TB)eradication efforts.Therefore,there is an urgent need to develop novel strategies to shorten TB treatment regimens and to treat drug-resistant TB.Using an albumin-fusion strategy,we created a novel albumin-fused granulocyte-macrophage colony-stimulating factor(albGM-CSF)molecule that harnesses albumin’s long half-life and targeting abilities to enhance the biostability of GM-CSF and direct it to the lymph nodes,where the effects of GM-CSF can increase dendritic cell populations crucial for eliciting a potent immune response.In this study,we demonstrate that albGM-CSF serves as a novel immunotherapy for chronic Mycobacterium tuberculosis(Mtb)infections by enhancing GM-CSF biostability in serum.Specifically,albumin is very safe,stable,and has a long half-life,thereby enhancing the biostability of GM-CSF.In the lungs and draining lymph nodes,albGM-CSF is able to increase the numbers of dendritic cells,which are crucial for the activation of naive T cells and for eliciting potent immune responses.Subcutaneous administration of albGM-CSF alone reduced the mean lung bacillary burden in mice with chronic tuberculosis infection.While GM-CSF administration was associated with IL-1βrelease from Mtb-infected dendritic cells and macrophages,higher IL-1βlevels were observed in albGM-CSF-treated mice with chronic tuberculosis infection than in mice receiving GM-CSF.Albumin fusion with GM-CSF represents a promising strategy for the control of chronic lung tuberculosis infections and serves as a novel therapeutic vaccination platform for other infectious diseases and malignancies.

Immunization with HBsAg-Fc fusion protein induces a predominant production of Thl cytokines and reduces HBsAg level in transgenic mice

Background The Fc receptor associated pathway might improve the immune responses against hepatitis B virus （HBV） as previously described by us. In addition, the Fit3 ligand （FL） has been reported to potentiate antigen presenting cells in vivo and may act as a potential adjuvant to boost antigen-specific immune responses. In this study, the immune efficacies of a set of fusion proteins of HBsAg and Fc and/or FL were evaluated in HBsAg transgenic mice. Methods The fusion proteins composed of HBsAg and the Fc domain of murine IgG1 （HBsAg-Fc） and/or the Fit3 ligand, and yeast-derived recombinant HBsAg were used as immunogen to immunize HBsAg transgenic mice, respectively. Serum and liver HBsAg levels, serum anti-HBsAg and cytokine profile, and the activities of alanine aminotransferase （ALT）/AST were investigated after immunization. Results After six injections, the most pronounced decrease in serum and liver HBsAg levels was observed in the HBsAg-Fc immunized group. In addition, serum Thl cytokines and ALT/AST activities were highest in this group, indicating an effective induction of a favorable cellular immune response. Interestingly, the fusion protein containing HBsAg-Fc and the Fit3 ligand stimulated an alternative Thl-type immune response featured with high level productions of tumor necrosis factor a （TNF-a） and monocyte chemoabstractant protein 1 （MCP-1）, causing a more severe cytotoxicity in hepatocytes while showed less effective in reducing serum HBsAg level. Conclusion HBsAg-Fc is effective in eliciting both the humeral and cellular immune responses against HBsAg in HBsAg transgenic mice, which makes it a potential immunogen for the immunotherapy of chronic hepatitis B.

Perspectives on the clinical development of mmunotherapy in prostate cancer

Despite impressive survival benefits with immunotherapy in patients with various solid tumors, the full potential of these agents in prostate cancer has yet to be realized. SipuleuceI-T demonstrated a survival benefit in this population, indicating that prostate cancer is an immunoresponsive disease; however, these results have not been matched by other agents. A large trial with ipilimumab in prostate cancer failed to meet its primary objective, and small trials with PD-1/PD-L1 inhibitors did not yield a significant improvement in overall response. However, several late-stage clinical trials are underway with other vaccines in prostate cancer. Reports of clinical benefit with immunotherapies, particularly when used in combination or a select population, have provided the framework to develop sound clinical trials. Understanding immunogenic modulation, antigen spread, biomarkers, and DNA-repair defects will also help mold future strategies. Through rational patient selection and evidence-based combination approaches, patients with prostate cancer may soon derive durable survival benefits with immunotherapies.

Cholesterol accumulation on dendritic cells reverses chronic hepatitis B virus infection-induced dysfunction

Chronic hepatitis B(CHB)infection remains a serious public health problem worldwide;however,the relationship between cholesterol levels and CHB remains unclear.We isolated peripheral blood mononuclear cells from healthy blood donors and CHB patients to analyze free cholesterol levels,lipid raft formation,and cholesterol metabolism-related pathways.Hepatitis B virus(HBV)-carrier mice were generated and used to confirm changes in cholesterol metabolism and cell-surface lipid raft formation in dendritic cells(DCs)in the context of CHB.Additionally,HBV-carrier mice were immunized with a recombinant HBV vaccine(rHBVvac)combined with lipophilic statins and evaluated for vaccine efficacy against HBV.Serum samples were analyzed for HBsAg,anti-HBs,and alanine aminotransferase levels,and liver samples were evaluated for HBV DNA and RNA and HBcAg.CHB reduced free cholesterol levels and suppressed lipid raft formation on DCs in patients with CHB and HBV-carrier mice,whereas administration of lipophilic statins promoted free cholesterol accumulation and restored lipid rafts on DCs accompanied by an enhanced antigen-presentation ability in vitro and in vivo.Cholesterol accumulation on DCs improved the rHBVvac-mediated elimination of serum HBV DNA and intrahepatic HBV DNA,HBV RNA,and HBcAg and promoted the rHBVvac-mediated generation and polyfunctionality of HBV-specific CD11a^(hi) CD8α^(lo) cells,induction of the development of memory responses against HBV reinfection,and seroconversion from HBsAg to anti-HBs.The results demonstrated the important role of cholesterol levels in DC dysfunction during CHB,suggesting that strategies to increase cholesterol accumulation on DCs might enhance therapeutic vaccine efficacy against HBV and support development toward clinical CHB treatment.