The route of administration dictates the immunogenicity of peptide-based cancer vaccines in mice

Immunotherapy targeting tumor-associated antigen in a mouse model of head and neck cancer

BACKGROUND

The identification of epitope peptides from tumor-associated antigens (TAAs) is informative for developing tumor-specific immunotherapy. However, only a few epitopes have been detected in mouse TAAs of head and neck cancer (HNSCC).

METHODS

Novel mouse c-Met-derived T-cell epitopes were predicted by computer-based algorithms. Mouse HNSCC cell line-bearing mice were treated with a c-Met peptide vaccine. The effects of CD8 and/or CD4 T-cell depletion, and vaccine combination with immune checkpoint inhibitors (ICIs) were evaluated. Tumor re-inoculation was performed to assess T-cell memory.

RESULTS

We identified c-Met-derived short and long epitopes that elicited c-Met-reactive antitumor CD8 and/or CD4 T-cell responses. Vaccination using these peptides showed remarkable antitumor responses via T cells in which ICIs were not required. The c-Met peptide-vaccinated mice rejected the re-inoculated tumors.

CONCLUSIONS

We demonstrated that novel c-Met peptide vaccines can induce antitumor T-cell response, and could be a potent immunotherapy in a syngeneic mouse HNSCC model.

From mice to men: An assessment of preclinical model systems for the study of vitiligo

Vitiligo is an autoimmune skin disease of multiple etiology, for which there is no complete cure. This chronic depigmentation is characterized by epidermal melanocyte loss, and causes disfigurement and significant psychosocial distress. Mouse models have been extensively employed to further our understanding of complex disease mechanisms in vitiligo, as well as to provide a preclinical platform for clinical interventional research on potential treatment strategies in humans. The current mouse models can be categorized into three groups: spontaneous mouse models, induced mouse models, and transgenic mice. Despite their limitations, these models allow us to understand the pathology processes of vitiligo at molecule, cell, tissue, organ, and system levels, and have been used to test prospective drugs. In this review, we comprehensively evaluate existing murine systems of vitiligo and elucidate their respective characteristics, aiming to offer a panorama for researchers to select the appropriate mouse models for their study.

Design and Evaluation of Synthetic Delivery Formulations for Peptide-Based Cancer Vaccines

With the recent advances in neoantigen identification, peptide-based cancer vaccines offer substantial potential in the field of immunotherapy. However, rapid clearance, low immunogenicity, and insufficient antigen-presenting cell (APC) uptake limit the efficacy of peptide-based cancer vaccines. This review explores the barriers hindering vaccine efficiency, highlights recent advancements in synthetic delivery systems, and features strategies for the key delivery steps of lymph node (LN) drainage, APC delivery, cross-presentation strategies, and adjuvant incorporation. This paper also discusses the design of preclinical studies evaluating vaccine efficiency, including vaccine administration routes and murine tumor models.

Locoregional drug delivery for cancer therapy: Preclinical progress and clinical translation

Systemic drug delivery is the current clinically preferred route for cancer therapy. However, challenges associated with tumor localization and off-tumor toxic effects limit the clinical effectiveness of this route. Locoregional drug delivery is an emerging viable alternative to systemic therapies. With the improvement in real-time imaging technologies and tools for direct access to tumor lesions, the clinical applicability of locoregional drug delivery is becoming more prominent. Theoretically, locoregional treatments can bypass challenges faced by systemic drug delivery. Preclinically, locoregional delivery of drugs has demonstrated enhanced therapeutic efficacy with limited off-target effects while still yielding an abscopal effect. Clinically, an array of locoregional strategies is under investigation for the delivery of drugs ranging in target and size. Locoregional tumor treatment strategies can be classified into two main categories: 1) direct drug infusion via injection or implanted port and 2) extended drug elution via injected or implanted depot. The number of studies investigating locoregional drug delivery strategies for cancer treatment is rising exponentially, in both preclinical and clinical settings, with some approaches approved for clinical use. Here, we highlight key preclinical advances and the clinical relevance of such locoregional delivery strategies in the treatment of cancer. Furthermore, we critically analyze 949 clinical trials involving locoregional drug delivery and discuss emerging trends.

Advances in Cancer Vaccine Research

The use of cancer vaccines is considered a promising therapeutic strategy in clinical oncology, which is achieved by stimulating antitumor immunity with tumor antigens delivered in the form of cells, peptides, viruses, and nucleic acids. The ideal cancer vaccine has many advantages, including low toxicity, specificity, and induction of persistent immune memory to overcome tumor heterogeneity and reverse the immunosuppressive microenvironment. Many therapeutic vaccines have entered clinical trials for a variety of cancers, including melanoma, breast cancer, lung cancer, and others. However, many challenges, including single antigen targeting, weak immunogenicity, off-target effects, and impaired immune response, have hindered their broad clinical translation. In this review, we introduce the principle of action, components (including antigens and adjuvants), and classification (according to applicable objects and preparation methods) of cancer vaccines, summarize the delivery methods of cancer vaccines, and review the clinical and theoretical research progress of cancer vaccines. We also present new insights into cancer vaccine technologies, platforms, and applications as well as an understanding of potential next-generation preventive and therapeutic vaccine technologies, providing a broader perspective for future vaccine design.

Improving the efficacy of peptide vaccines in cancer immunotherapy

Peptide vaccines have shown great potential in cancer immunotherapy by targeting tumor antigens and activating the patient's immune system to mount a specific response against cancer cells. However, the efficacy of peptide vaccines in inducing a sustained immune response and achieving clinical benefit remains a major challenge. In this review, we discuss the current status of peptide vaccines in cancer immunotherapy and strategies to improve their efficacy. We summarize the recent advancements in the development of peptide vaccines in pre-clinical and clinical settings, including the use of novel adjuvants, neoantigens, nano-delivery systems, and combination therapies. We also highlight the importance of personalized cancer vaccines, which consider the unique genetic and immunological profiles of individual patients. We also discuss the strategies to enhance the immunogenicity of peptide vaccines such as multivalent peptides, conjugated peptides, fusion proteins, and self-assembled peptides. Although, peptide vaccines alone are weak immunogens, combining peptide vaccines with other immunotherapeutic approaches and developing novel approaches such as personalized vaccines can be promising methods to significantly enhance their efficacy and improve the clinical outcomes for cancer patients.

[Research Progress of Lung Cancer Vaccines]

With the development of medical technology, tumor vaccines as a novel precise immunotherapy approach have gradually received attention in clinical applications. Against the backdrop of the global corona virus disease 2019 (COVID-19) outbreak, vaccine technology has further advanced. Depending on the types of antigens, tumor vaccines can be divided into whole-cell vaccines, peptide vaccines, messenger ribonucleic acid (mRNA) vaccines, recombinant virus vaccines, etc. Although some tumor vaccines have been marketed and achieved certain therapeutic effects, the results of tumor vaccines in clinical trials have been unsatisfactory in the past period. With the maturation of next-generation sequencing (NGS) technology and the continuous development of bioinformatics, dynamic monitoring of the entire process of tumor subpopulation development has become a reality, which has laid a solid foundation for personalized, neoantigen-centered therapeutic tumor vaccines. This article reviews the recent developments of tumor vaccines of different types, starts with lung cancer and summarizes the achievements of tumor vaccines in clinical applications, and provides an outlook for the future development of antigen-centered tumor vaccines.
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Brachyury-targeted immunotherapy combined with gemcitabine against head and neck cancer

Brachyury is a transcription factor belonging to the T-box gene family and is involved in the posterior formation of the mesoderm and differentiation of chordates. As the overexpression of Brachyury is a poor prognostic factor in a variety of cancers, the establishment of Brachyury-targeted therapy would be beneficial for the treatment of aggressive tumors. Because transcription factors are difficult to treat with a therapeutic antibody, peptide vaccines are a feasible approach for targeting Brachyury. In this study, we identified Brachyury-derived epitopes that elicit antigen-specific and tumor-reactive CD4⁺ T cells that directly kill tumors. T cells recognizing Brachyury epitopes were present in patients with head and neck squamous cell carcinoma. Next, we focused on gemcitabine (GEM) as an immunoadjuvant to augment the efficacy of antitumor responses by T cells. Interestingly, GEM upregulated HLA class I and HLA-DR expression in tumor, followed by the upregulation of anti-tumor T cell responses. As tumoral PD-L1 expression was also augmented by GEM, PD-1/PD-L1 blockade and GEM synergistically enhanced the tumor-reactivity of Brachyury-reactive T cells. The synergy between the PD-1/PD-L1 blockade and GEM was also confirmed in a mouse model of head and neck squamous cell carcinoma. These results suggest that the combined treatment of Brachyury peptide with GEM and immune checkpoint blockade could be a promising immunotherapy against head and neck cancer.

The nociceptive response induced by different classes of Tityus serrulatus neurotoxins: The important role of Ts5 in venom-induced nociception

Scorpion sting envenomations (SSE) are feared by the intense pain that they produce in victims. Pain from SSE is triggered mainly by the presence of neurotoxins in the scorpion venom that modulates voltage-gated ion channels. In Brazil, SSE is mostly caused by Tityus serrulatus, popularly known as yellow scorpion. Here, we evaluated experimental spontaneous nociception induced by T. serrulatus venom as well as its isolated neurotoxins Ts1, Ts5, Ts6, Ts8, and Ts19 frag II, evidencing different degrees of pain behavior in mice. In addition, we developed a mice-derived polyclonal antibody targeting Ts5 able to neutralize the effect of this neurotoxin, showing that Ts5 presents epitopes capable of activating the immune response, which decreased considerably the nociception produced by the whole venom. This is the pioneer study to explore nociception using different classes of T. serrulatus neurotoxins on nociception (α-NaTx, β-NaTx, α-KTx, and β-KTx), targeting potassium and sodium voltage-gated channels, besides demonstrating that Ts5 plays an important role in the scorpion sting induced-pain.

Mitogen-activated protein kinase inhibition augments the T cell response against HOXB7-expressing tumor through human leukocyte antigen upregulation

Homeobox B7 (HOXB7) is a master regulatory gene that regulates cell proliferation and activates oncogenic pathways. Overexpression of HOXB7 correlates with aggressive behavior and poor prognosis in patients with cancer. However, the expression and role of HOXB7 in head and neck squamous cell carcinoma (HNSCC) remain unclear. In this study, we observed that most samples from patients with oropharyngeal cancer and HNSCC expressed HOXB7. As no direct inhibitor has been reported, we identified a potent peptide epitope to target HOXB7-expressing tumors through immune cells. A novel HOXB7-derived peptide epitope (HOXB7_8-25 ) elicited antigen-specific and tumor-reactive promiscuous CD4⁺ T cell responses. These CD4⁺ T cells produced γ-interferon (IFN-γ) and had the direct ability to kill tumors through granzyme B. Notably, downregulation of HOXB7 using siRNA enhanced human leukocyte antigen class II expression on tumor cells by decreasing the phosphorylation of MAPK. Mitogen-activated protein kinase inhibition augmented IFN-γ production by HOXB7-reactive CD4⁺ T cell responses without decreasing the expression of HOXB7. These results suggest that combining HOXB7 peptide-based vaccine with MAPK inhibitors could be an effective immunological strategy for cancer treatment.

Potential association factors for developing effective peptide-based cancer vaccines

Peptide-based cancer vaccines have been shown to boost immune systems to kill tumor cells in cancer patients. However, designing an effective T cell epitope peptide-based cancer vaccine still remains a challenge and is a major hurdle for the application of cancer vaccines. In this study, we constructed for the first time a library of peptide-based cancer vaccines and their clinical attributes, named CancerVaccine (https://peptidecancervaccine.weebly.com/). To investigate the association factors that influence the effectiveness of cancer vaccines, these peptide-based cancer vaccines were classified into high (HCR) and low (LCR) clinical responses based on their clinical efficacy. Our study highlights that modified peptides derived from artificially modified proteins are suitable as cancer vaccines, especially for melanoma. It may be possible to advance cancer vaccines by screening for HLA class II affinity peptides may be an effective therapeutic strategy. In addition, the treatment regimen has the potential to influence the clinical response of a cancer vaccine, and Montanide ISA-51 might be an effective adjuvant. Finally, we constructed a high sensitivity and specificity machine learning model to assist in designing peptide-based cancer vaccines capable of providing high clinical responses. Together, our findings illustrate that a high clinical response following peptide-based cancer vaccination is correlated with the right type of peptide, the appropriate adjuvant, and a matched HLA allele, as well as an appropriate treatment regimen. This study would allow for enhanced development of cancer vaccines.

Cancer vaccines: Building a bridge over troubled waters

Cancer vaccines aim to direct the immune system to eradicate cancer cells. Here we review the essential immunologic concepts underpinning natural immunity and highlight the multiple unique challenges faced by vaccines targeting cancer. Recent technological advances in mass spectrometry, neoantigen prediction, genetically and pharmacologically engineered mouse models, and single-cell omics have revealed new biology, which can help to bridge this divide. We particularly focus on translationally relevant aspects, such as antigen selection and delivery and the monitoring of human post-vaccination responses, and encourage more aggressive exploration of novel approaches.

Antitumor Peptide-Based Vaccine in the Limelight

The success of the immune checkpoint blockade has provided a proof of concept that immune cells are capable of attacking tumors in the clinic. However, clinical benefit is only observed in less than 20% of the patients due to the non-specific activation of immune cells by the immune checkpoint blockade. Developing tumor-specific immune responses is a challenging task that can be achieved by targeting tumor antigens to generate tumor-specific T-cell responses. The recent advancements in peptide-based immunotherapy have encouraged clinicians and patients who are struggling with cancer that is otherwise non-treatable with current therapeutics. By selecting appropriate epitopes from tumor antigens with suitable adjuvants, peptides can elicit robust antitumor responses in both mice and humans. Although recent experimental data and clinical trials suggest the potency of tumor reduction by peptide-based vaccines, earlier clinical trials based on the inadequate hypothesis have misled that peptide vaccines are not efficient in eliminating tumor cells. In this review, we highlighted the recent evidence that supports the rationale of peptide-based antitumor vaccines. We also discussed the strategies to select the optimal epitope for vaccines and the mechanism of how adjuvants increase the efficacy of this promising approach to treat cancer.

Delivery of nanovaccine towards lymphoid organs: recent strategies in enhancing cancer immunotherapy

With the in-depth exploration on cancer therapeutic nanovaccines, increasing evidence shows that the poor delivery of nanovaccines to lymphoid organs has become the culprit limiting the rapid induction of anti-tumor immune response. Unlike the conventional prophylactic vaccines that mainly form a depot at the injection site to gradually trigger durable immune response, the rapid proliferation of tumors requires an efficient delivery of nanovaccines to lymphoid organs for rapid induction of anti-tumor immunity. Optimization of the physicochemical properties of nanovaccine (e.g., size, shape, charge, colloidal stability and surface ligands) is an effective strategy to enhance their accumulation in lymphoid organs, and nanovaccines with dynamic structures are also designed for precise targeted delivery of lymphoid organs or their subregions. The recent progress of these nanovaccine delivery strategies is highlighted in this review, and the challenges and future direction are also discussed.

Mimicking Pathogens to Augment the Potency of Liposomal Cancer Vaccines

Liposomes have emerged as interesting vehicles in cancer vaccination strategies as their composition enables the inclusion of both hydrophilic and hydrophobic antigens and adjuvants. In addition, liposomes can be decorated with targeting moieties to further resemble pathogenic particles that allow for better engagement with the immune system. However, so far liposomal cancer vaccines have not yet reached their full potential in the clinic. In this review, we summarize recent preclinical studies on liposomal cancer vaccines. We describe the basic ingredients for liposomal cancer vaccines, tumor antigens, and adjuvants, and how their combined inclusion together with targeting moieties potentially derived from pathogens can enhance vaccine immunogenicity. We discuss newly identified antigen-presenting cells in humans and mice that pose as promising targets for cancer vaccines. The lessons learned from these preclinical studies can be applied to enhance the efficacy of liposomal cancer vaccination in the clinic.

Cancer Vaccines: Promising Therapeutics or an Unattainable Dream

The advent of cancer immunotherapy has revolutionized the field of cancer treatment and offers cancer patients new hope. Although this therapy has proved highly successful for some patients, its efficacy is not all encompassing and several cancer types do not respond. Cancer vaccines offer an alternate approach to promote anti-tumor immunity that differ in their mode of action from antibody-based therapies. Cancer vaccines serve to balance the equilibrium of the crosstalk between the tumor cells and the host immune system. Recent advances in understanding the nature of tumor-mediated tolerogenicity and antigen presentation has aided in the identification of tumor antigens that have the potential to enhance anti-tumor immunity. Cancer vaccines can either be prophylactic (preventative) or therapeutic (curative). An exciting option for therapeutic vaccines is the emergence of personalized vaccines, which are tailor-made and specific for tumor type and individual patient. This review summarizes the current standing of the most promising vaccine strategies with respect to their development and clinical efficacy. We also discuss prospects for future development of stem cell-based prophylactic vaccines.

Recent progress on MHC-I epitope prediction in tumor immunotherapy

Tumor immunotherapy has now become one of the most potential therapy for those intractable cancer diseases. The antigens on the cancer cell surfaces are the keys for the immune system to recognize and eliminate them. As reported, the immunogenicity of the tumor antigens could be determined by the binding between the key epitope peptides and MHC molecules. In recent years, the approaches to anticipate the peptides from the candidate epitopes have gradually changed into more efficient methods. Including the improved conventional methods, more diverse methods were coming into view. Here we review the anticipated methods of the tumor associated epitopes that specifically bind with major histocompatibility complex (MHC) class I molecules, and the recent advances and applications of those epitope prediction methods.

Two-dimensional layered double hydroxide nanoadjuvant: recent progress and future direction

Layered double hydroxide (LDH) is a 'sandwich'-like two-dimensional clay material that has been systematically investigated for biomedical application in the past two decades. LDH is an alum-similar adjuvant, which has a well-defined layered crystal structure and exhibits high adjuvanticity. The unique structure of LDH includes positively charged layers composed of divalent and trivalent cations and anion-exchangeable interlayer galleries. Among the many variants of LDH, MgAl-LDH (the cationic ions are Mg2+ and Al3+) has the highest affinity to antigens, bioadjuvants and drug molecules, and exhibits superior biosafety. Past research studies indicate that MgAl-LDH can simultaneously load antigens, bioadjuvants and molecular drugs to amplify the strength of immune responses, and induce broad-spectrum immune responses. Moreover, the size and dispersity of MgAl-LDH in biological environments can be well controlled to actively deliver antigens to the immune system, realizing the rapid induction and maintenance of durable immune responses. Furthermore, the functionalization of MgAl-LDH nanoadjuvants enables it to capture antigens in situ and induce personalized immune responses, thereby more effectively overcoming complex diseases. In this review, we comprehensively summarize the development and application of MgAl-LDH nanoparticles as a vaccine adjuvant, demonstrating that MgAl-LDH is the most potential adjuvant for clinical application.

Interruption of MDM2 signaling augments MDM2-targeted T cell-based antitumor immunotherapy through antigen-presenting machinery

Identification of immunogenic tumor antigens, their corresponding T cell epitopes and the selection of effective adjuvants are prerequisites for developing effective cancer immunotherapies such as therapeutic vaccines. Murine double minute 2 (MDM2) is an E3 ubiquitin-protein ligase that negatively regulates tumor suppressor p53. Because MDM2 overexpression serves as a poor prognosis factor in various types of tumors, it would be beneficial to develop MDM2-targeted cancer vaccines. In this report, we identified an MDM2-derived peptide epitope (MDM2_32-46) that elicited antigen-specific and tumor-reactive CD4⁺ T cell responses. These CD4⁺ T cells directly killed tumor cells via granzyme B. MDM2 is expressed in head and neck cancer patients with poor prognosis, and the T cells that recognize this MDM2 peptide were present in these patients. Notably, Nutlin-3 (MDM2-p53 blocker), inhibited tumor cell proliferation, was shown to augment antitumor T cell responses by increasing MDM2 expression, HLA-class I and HLA-DR through class II transactivator (CIITA). These results suggest that the use of this MDM2 peptide as a therapeutic vaccine combined with MDM2 inhibitors could represent an effective immunologic strategy to treat cancer.

Peptides-based therapy and diagnosis. Strategies for non-invasive therapies in cancer

In recent years, remarkable progress was registered in the field of cancer research. Though, cancer still represents a major cause of death and cancer metastasis a problem seeking for urgent solutions as it is the main reason for therapeutic failure. Unfortunately, the most common chemotherapeutic agents are non-selective and can damage healthy tissues and cause side effects that affect dramatically the quality of life of the patients. Targeted therapy with molecules that act specifically at the tumour sites interacting with overexpressed cancer receptors is a very promising strategy for achieving the specific delivery of anticancer drugs, radioisotopes or imaging agents. This review aims to give an overview on different strategies for targeting cancer cell receptors localised either at the extracellular matrix or at the cell membrane. Molecules like antibodies, aptamers and peptides targeting the cell surface are presented with advantages and disadvantages, with emphasis on peptides. The most representative peptides are described, including cell penetrating peptides, homing and anticancer peptides with particular consideration on recent discoveries.

Double-Stranded RNA Immunomodulators in Prostate Cancer

Relatively simple, synthetic, double-stranded RNAs can be powerful viral pathogen-associated molecular pattern (PAMP) mimics, inducing a panoply of antiviral and antitumor responses that act at multiple stages of host defense. Their mechanisms of action and uses are beginning to be understood, alone, in combination with other therapeutics, or as novel PAMP-adjuvants providing the critical danger signal that has been missing from most cancer and other modern vaccines. Dose, timing, route of administration combinations, and other clinical variables can have a critical impact on immunogenicity. This article reviews advances in the use of polyinosinic-polycytidylic acid and derivatives, in particular poly-ICLC.

Lymphoid follicle antigen (Ag) delivery and enhanced rodent humoral immune responses mediated by Ag-containing PEGylated liposomes

Antigen (Ag) delivery to lymphoid follicles is important in achieving adaptive immunity. We recently developed a novel two-step Ag delivery system that efficiently induces cellular immune responses to Ags in mice by using priming intravenous (i.v.) injections of empty PEGylated liposomes (PEG-Lip) followed 3 days later by Ag-entrapped PEG-Lip (Ag-PEG-lip). In this study, we looked for humoral immune responses in rats and mice with IgG production specific to the encapsulated Ags. We observed that initial i.v. injections of empty PEG-Lip triggered accumulation of subsequent doses ovalbumin-PEG-Lip (OVA-PEG-lip) in splenic follicles and enhanced IgG production against OVA in both rats and mice. Anti-OVA IgG production was diminished by inhibition of splenic follicular accumulation of OVA-PEG-Lip by fingolimod (FTY720), which inhibits lymphocyte egress from lymphoid tissues. Thisindicates that the follicular accumulation of Ags that we observed is an indispensable and unique step in the production of anti-OVA IgG. Interestingly, in BALB/c nude mice, which are T cell deficient, a high follicular accumulation of OVA-PEG-Lip was observed, but anti-OVA IgG production was not observed. This suggests that T cells are also indispensable for the induction of cellular immune responses by our two-step immunization procedure. Our unique Ag delivery platform, which efficiently delivers Ags to splenic follicles, may be a useful technique for the enhancement of cellular immunity, as well as humoral immunity. Further experimental evaluation should be undertaken in relevant animal models in order for efficacy, safety and immunological correlates to be determined.

Expression of placenta-specific 1 and its potential for eliciting anti-tumor helper T-cell responses in head and neck squamous cell carcinoma

Placenta-specific 1 (PLAC1) is expressed primarily in placental trophoblasts but not in normal tissues and is a targetable candidate for cancer immunotherapy because it is a cancer testis antigen known to be up-regulated in various tumors. Although peptide epitopes capable of stimulating CD8 T cells have been previously described, there have been no reports of PLAC1 CD4 helper T lymphocyte (HTL) epitopes and the expression of this antigen in head and neck squamous cell carcinoma (HNSCC). Here, we show that PLAC1 is highly expressed in 74.5% of oropharyngeal and 51.9% of oral cavity tumors from HNSCC patients and in several HNSCC established cell lines. We also identified an HTL peptide epitope (PLAC1_31-50) capable of eliciting effective antigen-specific and tumor-reactive T cell responses. Notably, this peptide behaves as a promiscuous epitope capable of stimulating T cells in the context of more than one human leukocyte antigen (HLA)-DR allele and induces PLAC1-specific CD4 T cells that kill PLAC1-positive HNSCC cell lines in an HLA-DR-restricted manner. Furthermore, T-cells reactive to PLAC1_31-50 peptide were detected in the peripheral blood of HNSCC patients. These findings suggest that PLAC1 represents a potential target antigen for HTL based immunotherapy in HNSCC.

Palmitoylation of Membrane-Penetrating Magainin Derivatives Reinforces Necroptosis in A549 Cells Dependent on Peptide Conformational Propensities

Anticancer lipopeptides (ACLPs) are considered promising alternatives to combat resistant cancer cells, but the influence of peptide conformational propensity alone on their selectivity and mechanism remains obscure. In this study, we developed N-palmitoylated MK5E (P1MK5E) and MEK5 (P1MEK5) that have the same composition of 23 residues undergoing the pH-dependent structural alterations but differ in the conformational tendency of their amino acid composites. Nonlipidated peptides were readily accumulated in the A549 cell nucleus by the direct membrane translocation and the heparan sulfate-mediated endocytosis than the lipid-raft-dependent pathway. The increased hydrophobicity favored the amino acid-position-dependent folding of P1MK5E and P1MEK5, respectively, toward the α-helical coiled-coil nanofibrils and amyloidlike β-protofibrils. At the close concentrations (∼7.5 μM) to the toxic effects of doxorubicin (DOX), P1MK5E exhibited (i) an increased anticancer toxicity through a time-dependent S-phase arrest, (ii) enhanced plasma membrane permeability, and (iii) dose-dependent changes in the cell death characteristic features in the A549 cells relative to P1MEK5 that was almost inactive at ∼75 μM. These observations were in accordance with the TNF-α-mediated necroptotic signaling in the c-MYC/PARP1-overexpressed A549 cells exposed to P1MK5E and accompanied by the ultrastructure of plasma membrane protrusions, extensive endoplasmic reticulum (ER) membrane expansion, mitochondrial swelling, and the formation of distinct cytoplasmic vacuolation. The structural results and the bioactivity behaviors, herein, declared the significance of α-helical propensity in the peptide sequence and the nanostructure morphologies of self-assembling ACLPs upon the selectivity and enhanced anticancer effectiveness, which notably holds promise in the design and development of efficient therapeutics for cancer.

Feasibility of direct venous inoculation of the radiation-attenuated Plasmodium falciparum whole sporozoite vaccine in children and infants in Siaya, western Kenya

PfSPZ Vaccine, composed of radiation-attenuated, aseptic, purified, cryopreserved Plasmodium falciparum sporozoites, is administered by direct venous inoculation (DVI) for maximal efficacy against malaria. A critical issue for advancing vaccines that are administered intravenously is the ability to efficiently administer them across multiple age groups. As part of a pediatric safety, immunogenicity, and efficacy trial in western Kenya, we evaluated the feasibility and tolerability of DVI, including ease of venous access, injection time, and crying during the procedure across age groups. Part 1 was an age de-escalation, dose escalation trial in children aged 13 months-5 years and infants aged 5-12 months; part 2 was a vaccine efficacy trial including only infants, using the most skilled injectors from part 1. Injectors could use a vein viewer, if needed. A total of 1222 injections (target 0.5 mL) were initiated by DVI in 511 participants (36 were 5-9-year-olds, 65 were 13-59-month-olds, and 410 infants). The complete volume was injected in 1185/1222 (97.0%) vaccinations, 1083/1185 (91.4%) achieved with the first DVI. 474/511 (92.8%) participants received only complete injections, 27/511 (5.3%) received at least one partial injection (<0.5 mL), and in 10/511 (2.0%) venous access was not obtained. The rate of complete injections by single DVI for infants improved from 77.1% in part 1 to 92.8% in part 2. No crying occurred in 51/59 (86.4%) vaccinations in 5-9-year-olds, 25/86 (29.1%) vaccinations in 13-59-month-olds and 172/1067 (16.1%) vaccinations in infants. Mean administration time ranged from 2.6 to 4.6 minutes and was longer for younger age groups. These data show that vaccination by DVI was feasible and well tolerated in infants and children in this rural hospital in western Kenya, when performed by skilled injectors. We also report that shipping and storage in liquid nitrogen vapor phase was simple and efficient. (Clinicaltrials.gov NCT02687373).

Peptide-based materials for cancer immunotherapy

Peptide-based materials hold great promise as immunotherapeutic agents for the treatment of many malignant cancers. Extensive studies have focused on the development of peptide-based cancer vaccines and delivery systems by mimicking the functional domains of proteins with highly specific immuno-regulatory functions or tumor cells fate controls. However, a systemic understanding of the interactions between the different peptides and immune systems remains unknown. This review describes the role of peptides in regulating the functions of the innate and adaptive immune systems and provides a comprehensive focus on the design, categories, and applications of peptide-based cancer vaccines. By elucidating the impacts of peptide length and formulations on their immunogenicity, peptide-based immunomodulating agents can be better utilized and dramatic breakthroughs may also be realized. Moreover, some critical challenges for translating peptides into large-scale synthesis, safe delivery, and efficient cancer immunotherapy are posed to improve the next-generation peptide-based immunotherapy.

Molecular modelling of TLR agonist Pam3CSK4 entrapment in PLA nanoparticles as a tool to explain loading efficiency and functionality

Designing potent and safe-of-use therapies against cancers and infections remains challenging despite the emergence of novel molecule classes like checkpoint inhibitors or Toll-Like-Receptor ligands. The latest therapeutic perspectives under development for immune modulator administration exploits vectorization, and biodegradable delivery systems are one of the most promising vehicles. Nanoparticles based on Poly (D,L) Lactic Acid (PLA) as polymer for formulation are widely investigated due to its bioresorbable, biocompatible and low immunogen properties. We propose a PLA-based nanoparticle delivery system to vectorize Pam₃CSK₄, a lipopeptide TLR1/2 ligand and a potent activator of the proinflammatory transcription factor NF-κB that shows a self-assembling behavior from 30 µg/mL onwards. We demonstrate successful encapsulation of Pam₃CSK₄ in PLA nanoparticles by nanoprecipitation in a 40-180 µg/mL concentration range, with 99% of entrapment efficiency. By molecular modelling, we characterize drug/carrier interactions and conclude that Pam₃CSK₄ forms clusters onto the nanoparticle and is not encapsulated into the hydrophobic core. In silico predictions provide nanoprecipitation optimization and the mechanistic understanding of the particle dynamics. The loaded-Pam₃CSK₄ maintains bioactivity on TLR2, confirmed by in vitro experiments using reporter cell line HEK-Blue hTLR2. Our presented data and results are convincing evidence that Pam₃CSK₄-loaded in PLA nanoparticles represent a promising immune modulating system.