Antitumor Vaccines Research Articles

The immunogenicity of p24 protein from HIV-1 virus is strongly supported and modulated by coupling with liposomes and mannan

Anti-viral and anti-tumor vaccines aim to induce cytotoxic CD8+ T cells (CTL) and antibodies. Conserved protein antigens, such as p24 from human immunodeficiency virus, represent promising component for elicitation CTLs, nevertheless with suboptimal immunogenicity, if formulated as recombinant protein. To enhance immunogenicity and CTL response, recombinant proteins may be targeted to dendritic cells (DC) for cross presentation on MHCI, where mannose receptor and/or other lectin receptors could play an important role.Here, we constructed liposomal carrier-based vaccine composed of recombinant p24 antigen bound by metallochelating linkage onto surface of nanoliposomes with surface mannans coupled by aminooxy ligation. Generated mannosylated proteonanoliposomes were analyzed by dynamic light scattering, isothermal titration, and electron microscopy. Using murine DC line MutuDC and murine bone marrow derived DC (BMDC) we evaluated their immunogenicity and immunomodulatory activity.We show that p24 mannosylated proteonanoliposomes activate DC for enhanced MHCI, MHCII and CD40, CD80, and CD86 surface expression both on MutuDC and BMDC. p24 mannosylated liposomes were internalized by MutuDC with p24 intracellular localization within 1 to 3 h.The combination of metallochelating and aminooxy ligation could be used simultaneously to generate nanoliposomal adjuvanted recombinant protein-based vaccines versatile for combination of recombinant antigens relevant for antibody and CTL elicitation.

Transplantable Murine Tumors in the Studies of Peptide Antitumor Vaccines.

Numerous studies have shown that antitumor vaccines based on synthetic peptides are safe and can induce both CD8+ and CD4+ tumor-specific T cell responses. However, clinical results are still scarce, and such approach to antitumor treatment has not gained a wide implication, yet. Recently, particular advances have been achieved due to tumor sequencing and the search for immunogenic neoantigens caused by mutations. One of the most important issues for peptide vaccines, along with the choice of optimal adjuvants and vaccination regimens, is the search for effective target antigens. Extensive studies of peptide vaccines, including those on murine models, are required to reveal the effective vaccine constructs. The review presents transplantable murine tumors with the detected peptides that showed antitumor efficacy as a vaccine compound.

ITTCA-MVL: A multi-view learning model based on physicochemical information and sequence statistical information for tumor T cell antigens identification

Immunotherapy is an emerging treatment method aimed at activating the human immune system and relying on its own immune function to kill cancer cells and tumor tissues. It has the advantages of wide applicability and minimal side effects. Effective identification of tumor T cell antigens (TTCAs) will help researchers understand their functions and mechanisms and carry out research on anti-tumor vaccine development. Considering that using biological experimental technology to identify TTCAs can be costly and time-consuming, it is necessary to develop a robust bioinformatics computing tool. At present, different machine learning models have been proposed for identifying TTCAs, but there is still room for further improvement in their performance. To establish a TTCA predictor with better prediction performance, we propose a prediction model called iTTCA-MVL in this paper. We extracted three sets of features from the views of physicochemical information and sequence statistics, namely the distribution descriptor of composition, transition, and distribution (CTDD), TF-IDF, and LSA topic. Then, we used least squares support vector machines (LSSVMs) as submodels and Hilbert‒Schmidt independence criteria (HSIC) as constraints to establish an independent and complementary multi-view learning model. The prediction accuracy of iTTCA-MVL on the independent test set is 0.873, and Matthew's correlation coefficient is 0.747, which is significantly better than those of existing methods. Therefore, iTTCA-MVL is an excellent prediction tool that researchers can use to accurately identify TTCAs.

Potential of fluoropyrimidine to be an immunologically optimal partner of immune checkpoint inhibitors through inducing immunogenic cell death for thoracic malignancies.

Immune checkpoint inhibitors (ICIs) are a revolutionary paradigm in the treatment of thoracic malignancies and chemoimmunotherapy is a current standard care in this field. Chemotherapeutic agents are known to induce not only direct cytotoxic effects on tumor cells but also immune modulating effects, such as stimulating immunogenic cell death (ICD). Currently, either pemetrexed (PEM) or taxane plus platinum are combined with ICIs for patients with non-small cell lung cancer (NSCLC); however, it is still unknown whether these agents are immunologically optimal partners for ICIs. To determine the immunologically optimal chemotherapeutic agent, we first evaluated the ability of several chemotherapeutic agents, including platinum, PEM, taxane, and 5-fluorouracil (5-FU) to induce ICD using several thoracic tumor cell lines in vitro. ICD was evaluated by the cell surface expression of calreticulin (CRT) and adenosine-triphosphate (ATP) secretion. We further performed an antitumor vaccination assay in vivo. 5-FU induced cell surface expression of CRT and ATP secretion most efficiently among the several chemotherapeutic agents. This effect was enhanced when it was combined with platinum. In the antitumor vaccination assay in vivo, we found that vaccination with dying-AB1-HA (a murine malignant mesothelioma cell line) cells treated with 5-FU, but neither PEM nor PTX, reduced the tumor growth of living-AB1-HA cells inoculated 1 week after vaccination by recruiting CD3+ CD8+ T cells into the tumor microenvironment. Our findings indicate that fluoropyrimidine can be an immunologically optimal partner of ICIs through the induction of ICD for thoracic malignancies.

Efficacy of antitumor vaccines based on photoinduced GL261 glioma cells using photosensitizers from the group of tetra(aryl)tetracyanoporphyrases with different aryl substituents

Glioblastomas are solid tumors in the brain that pose a challenge for traditional treatments like surgery, radiation therapy, and chemotherapy. Complete cures are not guaranteed, and these treatments cause numerous side effects. First-line treatment approval has only been granted to Temozolomide (TMZ), the sole chemotherapy drug available. Using TMZ increases the median overall survival from 15 to 17 months. In general clinical practice, innovative interventions have not demonstrated efficacy due to glioma heterogeneity and their immunosuppressive microenvironment. Immunogenic cell death (ICD) activates an immune response against cancer cells by emitting damage-associated molecular patterns (DAMPs) upon cell death/dying. The DAMPs activate an anti-tumor immune response. Photodynamic therapy (PDT) can induce ICD. Integrating the principles of immunogenic cell death into glioma immunotherapy could elicit a targeted immune response against the diverse tumor. Vaccination with dendritic cells represents a promising approach for immunotherapy. The goals of this research are to evaluate the efficacy of a prophylactic vaccine using immunogenically-photoinduced glioma GL261 cells and a dendritic cell vaccine in an orthotopic in vivo model. The glioma cell line (GL261) is cultured in RPMI medium supplemented with 10% serum, L-glutamine, 1% penicillin, and 1% streptomycin in a CO2 incubator. Photodynamic treatment involves using photosensitizers from the tetra(aryl)tetracyanoporphyrazine group with 9-phenanthrenyl (pz I) or 4-(4-fluorobenzyloxy)phenyl (pz III) as side substituents. The GL261 cell line is incubated in a serum-free solution containing a selected porphyrazine for four hours. Subsequently, the solution is exchanged with complete medium and the cells are activated through photodynamic treatment at a dose of 20 J/cm2. The cells are then further incubated for 24 hours in a CO2 incubator. Immunizing mice includes subcutaneously injecting photoinduced GL261 glioma cell lysates twice with a 7-day interval. One week after the final immunization, viable GL261 glioma cells are injected into the brain using a stereotaxis frame. Measuring the neurological status of the animals occurs for 25 days, and tumor localization and volume are detected on day 23 by MRI. The survival rate of the experimental groups was 100% (pz III) or significantly higher (pz I) than that of the control groups. Additionally, neurological symptoms were either not identified (pz III) or were significantly lower (pz I) compared to the control animal groups experienced. The dendritic cell vaccine was based on photoinduced GL261 glioma cells. The femur and tibia bones of C57BL/6J mice were used and differentiated for 9 days in RPMI medium to isolate bone marrow stem cells. The medium was supplemented with 5% fetal bovine serum, 20 ng/ml GM-CSF, 1% L-glutamine, 1mM sodium pyruvate, 50 µM β-mercaptoethanol, 100 units/ml penicillin, and 100 µg/L streptomycin. The culture medium was renewed on days 3 and 6 to maintain stability. Protein levels are quantified in cell lysates collected. 2 mg of protein is added to a dendritic cell suspension, and after 90 minutes, 0.5 µg/ml lipopolysaccharide is added for 24 hours. Intraperitoneal dendritic cell vaccine immunization on animals is conducted, with injections 7 days apart. One week post-last immunization, viable GL261 cells are intracranially injected via a stereotactic frame. The neurological status of the animals was monitored for 25 days, and an MRI was conducted on day 23 to evaluate the brain tumor. The survival rate of animals in the experimental groups did not significantly differ from those in the control groups. However, the experimental groups exhibited significantly lower neurological symptoms, and the tumor was visualized without any areas of necrosis, with a smaller volume.

Engineering irradiated tumor-derived microparticles as personalized vaccines to enhance anti-tumor immunity

The inadequate activation of antigen-presenting cells, the entanglement of Tcells, and the highly immunosuppressive conditions in the tumor microenvironment (TME) are important factors that limit the effectiveness of cancer vaccines. Studies show that a personalized and broad antigen repertoire fully activates anti-tumor immunity and that inhibiting the function of transforming growth factor (TGF)-β facilitates Tcell migration. In our study, we introduce a vaccine strategy by engineering irradiated tumor cell-derived microparticles (RT-MPs), which have both personalized and broad antigen repertoire, to induce comprehensive anti-tumor effects. Encouraged by the proinflammatory effects of the spike protein from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the high affinity between TGF-β receptor 2 (TGFBR2) and TGF-β, we develop RT-MPs with the SARS-CoV-2 spike protein and TGFBR2. This spike protein and high TGFBR2 expression induce the innate immune response and ameliorate the immunosuppressive TME, thereby promoting Tcell activation and infiltration and ultimately inhibiting tumor growth. Our study provides a strategy for producing an effective personalized anti-tumor vaccine.

Boosting CAR T cells with anti-tumor mRNA vaccines.

Boosting CAR T cells with anti-tumor mRNA vaccines.

Establishing safe high hydrostatic pressure devitalization thresholds for autologous head and neck cancer vaccination and reconstruction

High hydrostatic pressure specifically devitalizes cells and tissues without major changes in their molecular structure. Hence, high hydrostatic pressure may enhance the development of whole-cell anti-tumor vaccines, representing tumor heterogeneity and thus (neo-) antigen diversity. Moreover, safe devitalization of tumor-infiltrated supporting tissue may facilitate reimplantation for functional reconstruction. However, precise high hydrostatic pressure thresholds for safe cancer cell killing are unknown. Here, we show that high hydrostatic pressure of at least 450 MPa is necessary to safely devitalize head and neck squamous cell cancer. A pressure of 300 MPa, which has been used frequently in cancer vaccine preparation, resulted in partial devitalization with 27% live cells in flow cytometry and 4% remaining autofluorescence in cell culture after one week. The remaining cells could form vital tumors in the chorioallantoic membrane assay. In contrast, 450 MPa killed all cells in vitro and prevented tumor outgrowth in ovo. The effectiveness of 450 MPa was attributed to the induction of DNA double-strand breaks, independent of apoptosis, autophagy, or methuosis. Furthermore, 450 MPa continued to induce immunogenic cell death. Our results demonstrate that 450 MPa of high hydrostatic pressure induces safe and sustained devitalization of head and neck cancer cells and tissues. Because of the heterogeneity in pressure resistance, we propose our approach as a starting point for determining the precise thresholds for other cancer entities. Further studies on head and neck cancer should focus on immunological co-cultures, combinations of immune checkpoint inhibition, and accurate anatomical reconstruction with pressure-treated autografts.

Cancer Cell Membrane Nanodiscs for Antitumor Vaccination.

Cell membrane-based nanovaccines have demonstrated attractive features due to their inherently multiantigenic nature and ability to be formulated with adjuvants. Here, we report on cellular nanodiscs fabricated from cancer cell membranes and incorporated with a lipid-based adjuvant for antitumor vaccination. The cellular nanodiscs, with their small size and discoidal shape, are readily taken up by antigen-presenting cells and drain efficiently to the lymph nodes. Due to its highly immunostimulatory properties, the nanodisc vaccine effectively stimulates the immune system and promotes tumor-specific immunity. Using a murine colorectal cancer model, strong control of tumor growth is achieved in both prophylactic and therapeutic settings, particularly in combination with checkpoint blockades. Considerable therapeutic efficacy is also observed in treating a weakly immunogenic metastatic melanoma model. This work presents a new paradigm for the design of multiantigenic nanovaccines that can effectively activate antitumor immune responses and may be applicable to a wide range of cancers.

Dendritic Cell-Derived Exosomes in Cancer Immunotherapy.

Exosomes are nanoscale vesicles released by diverse types of cells for complex intercellular communication. Numerous studies have shown that exosomes can regulate the body's immune response to tumor cells and interfere with the tumor microenvironment (TME). In clinical trials on dendritic cell (DC)-based antitumor vaccines, no satisfactory results have been achieved. However, recent studies suggested that DC-derived exosomes (DEXs) may be superior to DC-based antitumor vaccines in avoiding tumor cell-mediated immunosuppression. DEXs contain multiple DC-derived surface markers that capture tumor-associated antigens (TAAs) and promote immune cell-dependent tumor rejection. These findings indicate the necessity of the further development and improvement of DEX-based cell-free vaccines to complement chemotherapy, radiotherapy, and other immunotherapies. In this review, we highlighted the recent progress of DEXs in cancer immunotherapy, particularly by concentrating on landmark studies and the biological characterization of DEXs, and we summarized their important role in the tumor immune microenvironment (TIME) and clinical application in targeted cancer immunotherapy. This review could enhance comprehension of advances in cancer immunotherapy and contribute to the elucidation of how DEXs regulate the TIME, thereby providing a reference for utilizing DEX-based vaccines in clinical practice.

Unraveling tumor specific neoantigen immunogenicity prediction: a comprehensive analysis.

Identification of tumor specific neoantigen (TSN) immunogenicity is crucial to develop peptide/mRNA based anti-tumoral vaccines and/or adoptive T-cell immunotherapies; thus, accurate in-silico classification/prioritization proves critical for cost-effective clinical applications. Several methods were proposed as TSNs immunogenicity predictors; however, comprehensive performance comparison is still lacking due to the absence of well documented and adequate TSN databases. Here, by developing a new curated database having 199 TSNs with experimentally-validated MHC-I presentation and positive/negative immune response (ITSNdb), sixteen metrics were evaluated as immunogenicity predictors. In addition, by using a dataset emulating patient derived TSNs and immunotherapy cohorts containing predicted TSNs for tumor neoantigen burden (TNB) with outcome association, the metrics were evaluated as TSNs prioritizers and as immunotherapy response biomarkers. Our results show high performance variability among methods, highlighting the need for substantial improvement. Deep learning predictors were top ranked on ITSNdb but show discrepancy on validation databases. In overall, current predicted TNB did not outperform existing biomarkers. Recommendations for their clinical application and the ITSNdb are presented to promote development and comparison of computational TSNs immunogenicity predictors.

Key principles of drug therapy in patients with chronic myeloid leukemia

Objective: to summarize scientific information about the basic principles of modern drug therapy for patients with chronic myeloid leukemia (CML) considering their individual characteristics.Material and methods. The basis of the study included modern scientific articles and clinical guidelines on CML diagnosis and treatment (2021), State Register of Medicines (SRM) of the Russian Federation, instructions for the use of medicines. The following methods were used: structural analysis, analytical method, content analysis, retrospective analysis, systematic approach, situational-logical and graphical methods of analysis.Results. The analysis made it possible to summarize scientific information about the basic principles of drug therapy for patients suffering from CML. It was revealed that the problem of CML therapy today is relevant, since every year there is an increase in the incidence of this nosology. Currently, the most significant is the prescription of tyrosine kinase inhibitors (TKIs), since they have pronounced effects and are well tolerated by patients. Therapy for CML in TKIs prescription consists of several lines. Imatinib is the first line therapy because it has better safety profile. There are combinations with imatinib; for example, it is used together with interferon alfa, which allows, in some cases, to increase the response to treatment. The following drugs are used in the second line: nilotinib, dasatinib, bosutinib, ponatinib. If TKI therapy is ineffective, it is possible to prescribe standard chemotherapy, interferon therapy, or bone marrow transplantation in the absence of contraindications. Studies are underway on the possibility of using and including in clinical guidelines such drugs as arsenic trioxide, decitabine, omacetaxime, inhibitors of farnesyl transferases, granulocyte-macrophage factors, antitumor vaccines. The analysis of SRM identified 27 trade names for TKIs, the share of domestic drugs was 60%. There were no Russian analogues for bosutinib and ponatinib in SRM, which are recommended for use in case of ineffective TKI therapy of previous lines.Conclusion. The study of drug provision for CML patients is an urgent task for pharmaceutical practice and for the healthcare system as a whole. Currently, the acute issues are the individual approach to the treatment of each CML patient considering concomitant diseases, and the search for new, more effective drugs that can increase the life expectancy and quality of life of patients suffering from this disease.

Experience with multitargeted antitumor vaccine in a child with diffuse midline glioma, H3 K27M-mutant

Диффузная глиома высокой степени злокачественности (high-grade глиома) — наиболее часто встречающаяся высокозлокачественная первичная опухоль головного мозга с крайне агрессивным течением и неблагоприятным прогнозом.
 В статье описывается клинический случай 10-летнего ребенка с диффузной срединной глиомой головного мозга с альтерацией в гене H3 K27, которому после стандартного химиолучевого лечения в качестве поддерживающей терапии создан дендритноклеточный вакцинный препарат на основе иммуногенных раковотестикулярных и GD2 антигенов [(CTA+ (cancer-testis antigen) GD2+ (ganglioside)] вакцина). Опухолевый лизат был представлен глиобластомной клеточной культурой с экспрессией GD2 96%. В качестве ростовых и дифференцировочных факторов дендритных клеток, полученных из моноцитов периферической крови, были ГМ-КСФ (гранулоцитарно-макрофагальный колониестимулирующий фактор), ИЛ4 (интерлейкин 4) и ФНОα (фактор некроза опухоли α).
 Мультитаргетная иммунотерапия CTA+GD2+ аутологичной ДК-вакциной априори решает эволюционную проблему фенотипической гетерогенности и обладает большей клинической и иммунологической эффективностью в отношении high-grade глиом с их постепенным иммуноредактированием.

Rewiring innate and adaptive immunity with TLR9 agonist to treat osteosarcoma

BackgroundOsteosarcoma (OS) is the most common primary bone tumor in children and adolescent. Surgery and multidrug chemotherapy are the standard of treatment achieving 60–70% of event-free survival for localized disease at diagnosis. However, for metastatic disease, the prognosis is dismal. Exploiting immune system activation in the setting of such unfavorable mesenchymal tumors represents a new therapeutic challenge.MethodsIn immune competent OS mouse models bearing two contralateral lesions, we tested the efficacy of intralesional administration of a TLR9 agonist against the treated and not treated contralateral lesion evaluating abscopal effect. Multiparametric flow cytometry was used to evaluate changes of the tumor immune microenviroment. Experiments in immune-deficient mice allowed the investigation of the role of adaptive T cells in TLR9 agonist effects, while T cell receptor sequencing was used to assess the expansion of specific T cell clones.ResultsTLR9 agonist strongly impaired the growth of locally-treated tumors and its therapeutic effect also extended to the contralateral, untreated lesion. Multiparametric flow cytometry showed conspicuous changes in the immune landscape of the OS immune microenvironment upon TLR9 engagement, involving a reduction in M2-like macrophages, paralleled by increased infiltration of dendritic cells and activated CD8 T cells in both lesions. Remarkably, CD8 T cells were needed for the induction of the abscopal effect, whereas they were not strictly necessary for halting the growth of the treated lesion. T cell receptor (TCR) sequencing of tumor infiltrating CD8 T cells showed the expansion of specific TCR clones in the treated tumors and, remarkably, their selected representation in the contralateral untreated lesions, providing the first evidence of the rewiring of tumor-associated T cell clonal architectures.ConclusionsOverall these data indicate that the TLR9 agonist acts as an in situ anti-tumor vaccine, activating an innate immune response sufficient to suppress local tumor growth while inducing a systemic adaptive immunity with selective expansion of CD8 T cell clones, which are needed for the abscopal effect.Graphical

A promising self-nanoemulsifying adjuvant with plant-derived saponin D boosts immune response and exerts an anti-tumor effect.

The low immunogenicity of tumor antigens and unacceptable toxicity of adjuvants has hindered the application and development of tumor vaccines. Hence, we designed a novel anti-tumor vaccine composed of a plant-derived immunostimulant molecular nanoadjuvant (a self-nanoemulsifying system, SND) and the antigen OVA, to reinvigorate the immune response and inhibit tumor progression. In this study, this novel nanoadjuvant with Saponin D (SND) was designed and prepared by low-energy emulsification methods. Several important characteristics of the SND, including morphology, size, polymer dispersity index (PDI), zeta potential, and stability, were estimated, and the cytotoxicity of the SND was evaluated by MTT assay. Additionally, the immune response in terms of antibody titer levels and cellular immunity were evaluated in vivo after immunization with the vaccine, and the preventative and therapeutic effects of this novel vaccine against tumors were estimated. Finally, the antigen release profile was determined by IVIS imaging and by in vivo assay. This SND nanoadjuvant had good characteristics including the average particle size of 26.35 ± 0.225 nm, narrow distribution of 0.221 ± 1.76, and stability zeta potential of -12.9 ± 0.83 mV. And also, it had good stability (size, PDI, zeta potential, antigen stability) and low toxicity in vitro and in vivo, and delayed antigen release in vivo. The humoral immune response (IgG, IgG1, IgG2a, and IgG2b) and cellular immune level (cytokines of splenocytes including IFN-γ, IL-4, IL-1β andIL-17A) were both improved greatly after injected immunization at 0, 14, 28 days with the novel nanoadjuvant and antigen OVA. Importantly, this novel nanoadjuvant combined with OVA might lead to the induction of the prevent and treatment efficacy in the E.G7-OVA tumor-bearing mice. These results suggested that this novel nanoadjuvant encapsulated natural plant immunostimulant molecular OPD could be a good candidate of tumor vaccine adjuvant for reinvigorating the immune response and powerfully inhibiting tumor growth effect.

A platform trial of neoadjuvant and adjuvant antitumor vaccination alone or in combination with PD-1 antagonist and CD137 agonist antibodies in patients with resectable pancreatic adenocarcinoma

A neoadjuvant immunotherapy platform clinical trial allows for rapid evaluation of treatment-related changes in tumors and identifying targets to optimize treatment responses. We enrolled patients with resectable pancreatic adenocarcinoma into such a platform trial (NCT02451982) to receive pancreatic cancer GVAX vaccine with low-dose cyclophosphamide alone (Arm A; n = 16), with anti-PD-1 antibody nivolumab (Arm B; n = 14), and with both nivolumab and anti-CD137 agonist antibody urelumab (Arm C; n = 10), respectively. The primary endpoint for Arms A/B - treatment-related change in IL17A expression in vaccine-induced lymphoid aggregates - was previously published. Here, we report the primary endpoint for Arms B/C: treatment-related change in intratumoral CD8+ CD137+ cells and the secondary outcomes including safety, disease-free and overall survivals for all Arms. Treatment with GVAX+nivolumab+urelumab meets the primary endpoint by significantly increasing intratumoral CD8+ CD137+ cells (p = 0.003) compared to GVAX+Nivolumab. All treatments are well-tolerated. Median disease-free and overall survivals, respectively, are 13.90/14.98/33.51 and 23.59/27.01/35.55 months for Arms A/B/C. GVAX+nivolumab+urelumab demonstrates numerically-improved disease-free survival (HR = 0.55, p = 0.242; HR = 0.51, p = 0.173) and overall survival (HR = 0.59, p = 0.377; HR = 0.53, p = 0.279) compared to GVAX and GVAX+nivolumab, respectively, although not statistically significant due to small sample size. Therefore, neoadjuvant and adjuvant GVAX with PD-1 blockade and CD137 agonist antibody therapy is safe, increases intratumoral activated, cytotoxic T cells, and demonstrates a potentially promising efficacy signal in resectable pancreatic adenocarcinoma that warrants further study.

A synthetic Tn-BSA conjugate vaccine bearing chitotriose as built-in adjuvant

Chitotriose (CTS), the hydrolysate of chitosan, is readily soluble in water because of the shorter chain lengths of the oligomers and the free amino groups in the d-glucosamine units. In the current study, we report the synthesis of novel conjugate vaccine Tn-BSA-CTS with chitotriose as built-in adjuvant, along with an evaluation of the effect of adjuvant chitotriose (CTS). Immunological evaluations of the resultant conjugate vaccine revealed that Tn-BSA-CTS could provoke the highest titers of IgG antibodies (102,400). The Tn-BSA-CTS conjugate remarkably enhanced both humoral and cellular immunity. The obtained results demonstrate the potential of CTS as a novel vaccine adjuvant in the development of antitumor vaccine and the covalent linkage of tumor vaccine to CTS might be available strategy to increase the efficacy against cancer.

Approaches to the development of the dendritic cell and neoantigen-based antitumor vaccines

Approaches to the development of the dendritic cell and neoantigen-based antitumor vaccines

Tumor-informed circulating tumor DNA (TI-ctDNA) based molecular residual disease (MRD) detection and relapse risk for patients with stage II-IV melanoma in surgical remission: A single center experience.

9572 Background: Melanoma is associated with significant risk of relapse after surgery. While the odds of relapse increase with advancing stage, long term relapse free survival (RFS) is possible without adjuvant therapy in a significant subset of patients as shown by AJCC v8 staging long term survival data. TI-ctDNA (Signatera™) is a non-invasive biomarker for MRD detection and functions by sequencing the patient’s own tumor for the creation of a customized panel of PCR probes based upon a tumor’s unique mutational profile. Positive TI-ctDNA testing is significantly associated with relapse after surgical resection in colorectal cancer and may help inform treatment decision-making, allowing for intensification or de-intensification of patient management. This study describes the operating characteristics of TI-ctDNA in monitoring for relapse in patients with resected melanoma. Methods: This is a single center retrospective analysis of patients with stage IIb-IV melanoma in surgical remission. Between January 2021 and January 2023, male and female patients presenting in surgical remission were monitored with TI-ctDNA at 6- or 12-week intervals. Surveillance imaging for relapse was performed according to standard of care guidelines appropriate for tumor stage. Patients were treated with immunotherapy, targeted therapy, or melanoma specific anti-tumor vaccine. Duration of RFS from surgery to detectable TI-ctDNA was recorded, along with duration of RFS from surgery to confirmed melanoma relapse. Results: 45 eligible patients were included in the analysis. 10 patients had detectable TI-ctDNA during the study period. 7 patients had confirmed relapse, 6 of whom were TI-ctDNA positive and 1 who was TI-ctDNA negative. The total relapse rate in TI-ctDNA positive patients (6/10) was significantly higher than the relapse rate in TI-ctDNA negative patients (1/35) [p = 0.0002]. Time to detection of positive TI-ctDNA was variable and ranged from 0 to 664 days (median 73 days). Conclusions: TI-ctDNA testing demonstrated preliminary ability to differentiate melanoma patients at the highest risk of relapse. Prospective evaluation of TI-ctDNA monitoring for determination of patients at high versus low risk of relapse is warranted and may help to inform future clinical trial designs by allowing for patient stratification to low risk (undetectable TI-ctDNA) and high risk (detectable TI-ctDNA) disease states.

Computational and Experimental Evaluation of the Immune Response of Neoantigens for Personalized Vaccine Design.

In the last few years, the importance of neoantigens in the development of personalized antitumor vaccines has increased remarkably. In order to study whether bioinformatic tools are effective in detecting neoantigens that generate an immune response, DNA samples from patients with cutaneous melanoma in different stages were obtained, resulting in a total of 6048 potential neoantigens gathered. Thereafter, the immunological responses generated by some of those neoantigens ex vivo were tested, using a vaccine designed by a new optimization approach and encapsulated in nanoparticles. Our bioinformatic analysis indicated that no differences were found between the number of neoantigens and that of non-mutated sequences detected as potential binders by IEDB tools. However, those tools were able to highlight neoantigens over non-mutated peptides in HLA-II recognition (p-value 0.03). However, neither HLA-I binding affinity (p-value 0.08) nor Class I immunogenicity values (p-value 0.96) indicated significant differences for the latter parameters. Subsequently, the new vaccine, using aggregative functions and combinatorial optimization, was designed. The six best neoantigens were selected and formulated into two nanoparticles, with which the immune response ex vivo was evaluated, demonstrating a specific activation of the immune response. This study reinforces the use of bioinformatic tools in vaccine development, as their usefulness is proven both in silico and ex vivo.