Neoantigen Vaccines Research Articles

Combination treatment of radiofrequency ablation and peptide neoantigen vaccination: Promising modality for future cancer immunotherapy.

3151 Background: We previously reported the safety and immunogenicity of a personalized neoantigen-based peptide vaccine, iNeo-Vac-P01, in patients with a variety of cancer types. The current study investigated the synergistic effects between radiofrequency ablation (RFA) and neoantigen vaccination in cancer patients and tumor-bearing mice. Methods: 28 cancer patients were enrolled in this study, including 10 patients who had received RFA treatment within 6 months before scheduled for vaccination, and 18 patients who had not. Individualized neoantigen peptide vaccines were designed, manufactured, and delivered for all patients, followed by subcutaneous administration of GM-CSF as an adjuvant. Mouse models were used to validate the synergistic efficacy of combination treatment of RFA and neoantigen vaccination. Results: Longer median progression free survival (mPFS) and median overall survival (mOS) were observed in patients receiving RFA prior to vaccines compared to patients only receiving vaccines (4.42 and 20.18 months vs. 2.82 and 10.94 months). Ex vivo ELISpot assay showed that patients who received both had stronger IFN-γ responses against patient-specific neoantigens at baseline and post vaccination. Mice receiving RFA together with vaccine displayed higher antitumor immune responses than mice receiving single modality; addition of anti-PD-1 further enhanced the antitumor response. Conclusions: Neoantigen vaccination after RFA treatment led to an overall increase in clinical response and immune response among patients of different cancer types. Combination treatment of both modalities in mice further validated their synergistic antitumor potentials, which could be further enhanced by the addition of anti-PD-1. The mechanisms of their synergies require further investigation. Clinical trial information: NCT03662815.

Phase 2/3, randomized, open-label study of an individualized neoantigen vaccine (self-amplifying mRNA and adenoviral vectors) plus immune checkpoint blockade as maintenance for patients with newly diagnosed metastatic colorectal cancer (GRANITE).

TPS3635 Background: Treatment options for most patients with metastatic colorectal cancer (mCRC) are largely limited to cytotoxic chemotherapy, with little advancement in the last decade. Encouragingly, a small subset of patients deficient in mismatch repair (dMMR/MSI-hi) benefit from checkpoint inhibitors (CPI) whereas those proficient in mismatch repair (pMMR/MSS) do not. The absence of clinical benefit in patients with pMMR/MSS mCRC may relate to a lack of neoantigen-specific T cells and immune infiltration. An individualized neoantigen vaccine that induces CD8 T cells capable of tumor lysis has the potential to expand the number of patients with mCRC who may benefit from immunotherapy. Data from a Phase 1/2 study evaluating neoantigen vaccines in combination with CPIs in patients with previously treated mCRC demonstrated a 44% molecular response (MR) rate (≥50% decrease in ctDNA relative to baseline) in 4/9 patients; this correlated with improvement in OS relative to those without a MR. To further investigate neoantigen vaccines in earlier lines of treatment, a Phase 2/3 study in the1L maintenance setting in mCRC was initiated. Methods: GO-010 is a Phase 2/3, randomized, open-label, multi-center study evaluating the efficacy and safety of 2 neoantigen-containing vectors (GRT-C901-adenoviral vector plus GRT-R902-self-amplifying mRNA vector) as prime/boost in combination with CPIs as an add-on to fluoropyrimidine/bevacizumab (bev) following 1L therapy with FOLFOX/bev in patients with mCRC. During Phase 2, up to 90 patients will be randomized 1:1 to the vaccine or control arm with a primary objective of assessing efficacy by MR. During Phase 3, up to 226 patients will be randomized with a primary objective of assessing PFS per iRECIST in a blinded, independent manner. There are two stages to the study. In the vaccine production stage, while patients receive FOLFOX/bev 1L therapy, neoantigen prediction is performed using a tumor biopsy and Gritstone’s EDGE™ neoantigen prediction model. For patients in the vaccine arm the top 20 predicted neoantigens are included in the vaccine vectors. After completing oxaliplatin, patients will enter the study treatment stage. Patients in the control arm will continue with maintenance therapy whereas patients in the vaccine arm will add the vaccine regimen to maintenance therapy. The vaccine regimen consists of GRT-C901/GRT-R902 as well as SC ipilimumab (30 mg) and IV atezolizumab (1680 mg). Over the first year of treatment, 6 vaccinations will occur. Ipilimumab will be administered SC with the first doses of GRT-C901 and GRT-R902. Atezolizumab will be administered every 4 weeks for up to 2 years. Study assessments include imaging, ctDNA, safety, immunogenicity and exploratory biomarker analysis. Clinical trial information: NCT05141721.

Phase 1 studies of personalized neoantigen vaccine TG4050 in ovarian carcinoma (OC) and head and neck squamous cell carcinoma (HNSCC).

2637 Background: Mutation-associated neoantigens (MANAs) constitute attractive antigens for the design of cancer vaccines. However, clinical implementation remains challenging because of the patient specific nature of MANAs, hereby requiring that a bespoke vaccine is designed for each subject. We developed a pipeline for the genomic characterization and the design of tailored vaccine using a modified vaccinia Ankara viral vector. Methods: Immunogenicity, safety and early clinical activity of personalized cancer vaccines are being assessed in two phase I trials, respectively in high grade serous OC and HPV-negative HNSCC. Patients (Pts) at high risk of relapse are enrolled in the study being in remission following surgical primary treatment. High risk is defined as stage IIIC or IVA for OC and stage III or IVA for HNSCC. A vaccine is manufactured for each patient. OC pts are treated at asymptomatic relapse based on radiological finding or elevation of CA-125 with the vaccine alone; HNSCC pts in complete remission after surgery and adjuvant therapy are randomized to receive the vaccine either at the end of locoregional treatment or in combination with standard of care at relapse. The vaccine was administered weekly for 6 weeks and a booster dose every three weeks over a year or until progression, whichever occurred first. Results: At the time of the data cut-off, a total of 8 pts were treated: 4 relapsing OC pts, 3 HNSCC pts in complete remission and 1 relapsing HNSCC pt. AE attributable to the vaccine were mainly grade 1 injection site reactions and fatigue. One OC pt displayed an objective response 6 weeks after initiation of vaccine and for 9 months with a normalization of CA-125 until death from an unrelated cause; 1 other OC pt remains on treatment with a stable radiological disease for 11 months. The 2 other OC progressed at the first evaluation on day 43. HNSCC pts treated in complete remission received respectively 20, 15 and 4 doses, and remain on treatment and disease free. One HNSCC patient received 9 doses of vaccine after relapse in conjunction with chemotherapy and anti-PD-1 therapy and remains on treatment with stable disease after 5 months. Immune monitoring demonstrates priming of a polyepitopic T cell response against class I and II antigens. Responses were observed regardless of HLA and without cross-reactivity to the germline protein. Adaptive response was associated with a shift of CD4 and CD8 T cells toward an effector phenotype and innate cellular immunity was activated with a strong maturation and activation of NK cells. Immune changes were stronger in pts with controlled disease versus progressors. Conclusions: Data demonstrate that TG4050 is safe, well tolerated and able to induce T cell responses whatever the HLA haplotype. Early signs of clinical activity were observed in OC pt. These data pave the way for further development and synergistic immunotherapeutic combinations. Clinical trial information: NCT04183166.

Personalized neoantigen DNA vaccines expand tumor-specific T cells in the periphery which infiltrate the tumor in hepatocellular carcinoma.

2638 Background: Tumor neoantigens are epitopes derived from tumor-specific mutations that can be incorporated in personalized vaccines to prime T cell responses. DNA vaccines delivered with electroporation have recently shown strong CD8 and CD4 T cell responses in clinical trials. In preclinical studies, DNA-encoded neoantigen vaccines have shown induction of CD8 T cells against 50% of predicted high affinity epitopes with the ability to impact tumor growth. Methods: Paired blood and tumor biopsy samples were collected from a patient with hepatocellular carcinoma before and after treatment with GNOS-PV02 (DNA neoantigen targeted vaccine) + plasmid IL-12 + pembrolizumab. Treatment resulted in a partial response with a decrease in tumor size of 44% by RECIST (168 mm to 94 mm). TCRbeta sequencing was performed on all 4 samples and single cell TCR and transcriptome sequencing was performed from T cells isolated from the post-treatment blood sample. Newly identified TCRs in blood and tumor after vaccination were inserted into an expression vector and used to generate engineered TCR T cells. Engineered TCR T cells were tested against the neoantigens included in the vaccine and their responses characterized by flow cytometry. Results: We identified 67,893 new clones in PBMC after vaccination, 3 of which comprised between 0.1 to 1% of the total T cell clones. Moreover, we identified 5126 new clones in the tumor post vaccination, out of these, 3878 (75.68%) were not found within the patient’s pre vaccination PBMCs and 556 (10.86%) were identified within the pre vaccination PBMC pool. Importantly, of the newly identified T cells infiltrating the tumor post vaccination, we observed high frequency TCR clones of which 44 and 7 clones were above 0.1% and 1%, respectively. The majority of the newly identified T cell clones were CD8 T cells (68.75%) with an activated phenotype. Importantly, the 6 most expanded clones in blood were identified to be activated CD8+CD69+ T cells (81.82%). Engineered TCR T cells generated encoding the TCRs of these newly identified CD8 T cells showed activation when exposed to the tumor neoantigens encoded in the neoantigen DNA vaccine GNOS-PV02. Conclusions: GNOS-PV02, a neoantigen DNA vaccine, in combination with plasmid IL-12 and pembrolizumab resulted in expansion of newly identified T cells, primarily activated CD8, which trafficked to the tumor. These new tumor infiltrating T cells showed TCR specificity against tumor neoantigens encoded in GNOS-PV02 and may account for the observed objective decrease in tumor size.

Lymph Nodes as Anti-Tumor Immunotherapeutic Tools: Intranodal-Tumor-Specific Antigen-Pulsed Dendritic Cell Vaccine Immunotherapy.

Simple SummaryIn the field of cancer therapy, lymph nodes are important not only as targets for metastases resection but also as prudent target organs for cancer immunotherapy. Lymph nodes comprise a complete structure for the accumulation of a large number of T cells and their distribution throughout the body after antigen presentation and activation of dendritic cells. This review highlights current topics on the importance of lymph node structure in antitumor immunotherapy and intranodal-antigen-presenting mature dendritic cell vaccine therapy. We also discuss the rationale behind intranodal injection methods and their applications in neoantigen vaccine therapy, a new cancer immunotherapy.Hundreds of lymph nodes (LNs) are scattered throughout the body. Although each LN is small, it represents a complete immune organ that contains almost all types of immunocompetent and stromal cells functioning as scaffolds. In this review, we highlight the importance of LNs in cancer immunotherapy. First, we review recent reports on structural and functional properties of LNs as sites for antitumor immunity and discuss their therapeutic utility in tumor immunotherapy. Second, we discuss the rationale and background of ultrasound (US)-guided intranodal injection methods. In addition, we review intranodal administration therapy of tumor-specific-antigen-pulsed matured dendritic cells (DCs), including neoantigen-pulsed vaccines.

Novel RNA-based Cancer Vaccine for AML immunotherapy

Abstract Acute Myeloid Leukemia is a rapidly progressing malignancy relying primarily on chemotherapy as the frontline treatment option. Success of personalized neoantigen vaccines in melanoma patients has garnered great attention in the field of immunotherapy. We hypothesize that personalized cancer vaccine, in the form of mRNA, can be a viable treatment strategy for AML patients. Next generation sequencing was performed on both C57BL6Jinv mouse’s and C1498 cell line’s nucleic acid materials. Three different neoepitope prediction pipelines were utilized to identify potential immunogenic neoepitopes. Candidate neoepitopes within intron polyadenlyation sites (iPAS), retained intron (RI) sites and somatic mutation (SM) sites were found. A total of 285 SM-derived neoepitopes were identified. Top 38 highly expressed genes were selected for further analysis. Using Sanger sequencing, we confirmed 37 out of the 38 mutations. A total of 5 iPAS-derived neoepitopes were identified. A total of 26 RI-derived neoepitopes were identified in our first RNAseq analysis and a separate 476 RI-derived neoepitopes were identified in our second RNAseq analysis. With these three categories of candidates, we narrowed down our selection and did a preliminary screen for immunogenic epitopes using a total of 71 synthetic peptides in an ELISpot assay. Conventional ELISpot assay’s results were however non-reproducible, thereby propelling us to adopt Culture ELISpot assay. Subsequently, 10 neoepitope candidates were short-listed for further in-vivo evaluation. mRNA vaccine was synthesized and evaluated in a murine AML model. T cell responses against the 10 neoepitopes were analyzed to provide pre-clinical evidence for patient studies. Supported by NMRC CS-IRG grant

Immune Checkpoint Blockade Enhances Efficacy of Neoantigen Vaccine

Immune checkpoint blockade enhances the cytotoxic T-cell response primed by neoantigen vaccines.

Concurrent delivery of immune checkpoint blockade modulates T cell dynamics to enhance neoantigen vaccine-generated antitumor immunity.

Neoantigen vaccines aiming to induce tumor-specific T cell responses have achieved promising anti-tumor effects in early clinical trials. However, the underlying mechanism regarding response or resistance to this treatment remains unclear. Here, we observe that neoantigen vaccine-generated T cells can synergize with immune checkpoint blockade (ICB) for effective tumor control. Specifically, we performed single-cell sequencing on over 100,000 T cells and uncovered that combined therapy induces an antigen-specific CD8 T cell population with active chemokine signaling (Cxcr3+/Ccl5+), lower co-inhibitory receptor expression (Lag3−/Havcr2−) and higher cytotoxicity (Fasl+/Gzma+). Furthermore, the generation of neoantigen-specific T cells in the draining lymph node is required for combination treatment. Signature genes of this unique population are associated with T cell clonal frequency and better survival in humans. Our study profiles the dynamics of tumor infiltrated T cells during neoantigen vaccine and ICB treatments, high-dimensionally identifies neoantigen-reactive T cell signatures for future development of therapeutic strategies.

On the development of a neoantigen vaccine for the prevention of Lynch Syndrome

Lynch Syndrome (LS) is an autosomal dominant genetic condition that causes a high risk of colorectal cancer. The hallmark of LS is genetic instability as a result of mismatch repair (MMR) deficiency, particularly in repetitive low complexity regions called microsatellites (MS). MLH1-/- mice deficient in MMR are prone to developing tumors in the colon, upon oral administration of dextran sodium sulfate (DSS), at a rate of more than 70%. Using this LS mouse model, we found a novel tumor neo-antigen from a deletion mutation of the coding MS in the SENP6 gene that prevented tumorigenesis or hindered tumor growth rate in immunized mice. This was accomplished via high throughput exome sequencing of DSS-induced colorectal tumors in the MLH1-/- mice and predicting the most highly immunogenic mutant gene products processed and presented as antigens in C57BL/6 MHC-I molecules. Throughout our study, we were able to prove the validity of the vaccine by analyzing the colorectal tumors in immunized DSS-treated mice using either our epitope, called Sp6D1, or an unrelated peptide as a negative control. Tumors developed in this context were found to be antigenic and Sp6D1-specific CD8+ tumor infiltrating lymphocytes were detected by flow cytometry and cytotoxic T lymphocytes (CTL) killing assays. Additionally, immunohistochemistry showed that tumor-adjacent tertiary lymphoid organs were a potentially significant source of CD8+ lymphocytes. Altogether, our results indicate that there may be a protective effect to patients carrying LS mutations through the induction of a peptide-specific CTL response from the use of neoepitope vaccination.

Defined tumor antigen-specific T cells potentiate personalized TCR-T cell therapy and prediction of immunotherapy response.

Personalized immunotherapy targeting tumor-specific antigens (TSAs) could generate efficient and safe antitumor immune response without damaging normal tissues. Although neoantigen vaccines have shown therapeutic effect in clinic trials, precise prediction of neoantigens from tumor mutations is still challenging. The host antitumor immune response selects and activates T cells recognizing tumor antigens. Hence, T cells engineered with T-cell receptors (TCRs) from these naturally occurring tumor antigen-specific T (Tas) cells in a patient will target personal TSAs in his/her tumor. To establish such a personalized TCR-T cell therapy, we comprehensively characterized T cells in tumor and its adjacent tissues by single-cell mRNA sequencing (scRNA-seq), TCR sequencing (TCR-seq) and in vitro neoantigen stimulation. Compared to bystander T cells circulating among tissues, Tas cells were characterized by tumor enrichment, tumor-specific clonal expansion and neoantigen specificity. We found that CXCL13 is a unique marker for both CD4+ and CD8+ Tas cells. Importantly, TCR-T cells expressing TCRs from Tas cells showed significant therapeutic effects on autologous patient-derived xenograft (PDX) tumors. Intratumoral Tas cell levels measured by CXCL13 expression precisely predicted the response to immune checkpoint blockade, indicating a critical role of Tas cells in the antitumor immunity. We further identified CD200 and ENTPD1 as surface markers for CD4+ and CD8+ Tas cells respectively, which enabled the isolation of Tas cells from tumor by Fluorescence Activating Cell Sorter (FACS) sorting. Overall, our results suggest that TCR-T cells engineered with Tas TCRs are a promising agent for personalized immunotherapy, and intratumoral Tas cell levels determine the response to immunotherapy.

Potent adjuvant effect elicited for tumor immunotherapy by a liposome conjugated pH-sensitive polymer and dendritic cell-targeting Toll-like-receptor ligand

The generation of DCs with augmented functions is a strategy for obtaining satisfactory clinical outcomes in tumor immunotherapy. We developed a novel synthetic adjuvant comprising a liposome conjugated with a DC-targeting Toll-like-receptor ligand and a pH-sensitive polymer for augmenting cross-presentation. In an in vitro study using mouse DCs, these liposomes were selectively incorporated into DCs, significantly enhanced DC function and activated immune responses to present an epitope of the incorporated antigen on the major histocompatibility complex class I molecules. Immunization of mice with liposomes encapsulating a tumor antigen significantly enhanced antigen-specific cytotoxicity. In tumor-bearing mice, vaccination with liposomes encapsulating a tumor antigen elicited complete tumor remission. Furthermore, vaccination significantly enhanced cytotoxicity, targeting not only the vaccinated antigen but also the other antigens of the tumor cell. These results indicate that liposomes are an ideal adjuvant to develop DCs with considerably high potential to elicit antigen-specific immune responses; they are a promising tool for cancer therapy with neoantigen vaccination.

Peptidic microarchitecture-trapped tumor vaccine combined with immune checkpoint inhibitor or PI3Kγ inhibitor can enhance immunogenicity and eradicate tumors

BackgroundWith the rapid development of immune checkpoint inhibitors and neoantigen (NeoV)-based personalized tumor vaccines, tumor immunotherapy has shown promising therapeutic results. However, the limited efficacy of available tumor vaccines impedes...

Personalized therapy with peptide-based neoantigen vaccine (EVX-01) including a novel adjuvant, CAF®09b, in patients with metastatic melanoma

ABSTRACT The majority of neoantigens arise from unique mutations that are not shared between individual patients, making neoantigen-directed immunotherapy a fully personalized treatment approach. Novel technical advances in next-generation sequencing of tumor samples and artificial intelligence (AI) allow fast and systematic prediction of tumor neoantigens. This study investigates feasibility, safety, immunity, and anti-tumor potential of the personalized peptide-based neoantigen vaccine, EVX-01, including the novel CD8+ T-cell inducing adjuvant, CAF®09b, in patients with metastatic melanoma (NTC03715985). The AI platform PIONEERTM was used for identification of tumor-derived neoantigens to be included in a peptide-based personalized therapeutic cancer vaccine. EVX-01 immunotherapy consisted of 6 administrations with 5–10 PIONEERTM-predicted neoantigens as synthetic peptides combined with the novel liposome-based Cationic Adjuvant Formulation 09b (CAF®09b) to strengthen T-cell responses. EVX-01 was combined with immune checkpoint inhibitors to augment the activity of EVX-01-induced immune responses. The primary endpoint was safety, exploratory endpoints included feasibility, immunologic and objective responses. This interim analysis reports the results from the first dose-level cohort of five patients. We documented a short vaccine manufacturing time of 48–55 days which enabled the initiation of EVX-01 treatment within 60 days from baseline biopsy. No severe adverse events were observed. EVX-01 elicited long-lasting EVX-01-specific T-cell responses in all patients. Competitive manufacturing time was demonstrated. EVX-01 was shown to be safe and able to elicit immune responses targeting tumor neoantigens with encouraging early indications of a clinical and meaningful antitumor efficacy, warranting further study.

Engineering neoantigen vaccines to improve cancer personalized immunotherapy.

Immunotherapy treatments harnessing the immune system herald a new era of personalized medicine, offering considerable benefits for cancer patients. Over the past years, tumor neoantigens emerged as a rising star in immunotherapy. Neoantigens are tumor-specific antigens arising from somatic mutations, which are proceeded and presented by the major histocompatibility complex on the cell surface. With the advancement of sequencing technology and bioinformatics engineering, the recognition of neoantigens has accelerated and is expected to be incorporated into the clinical routine. Currently, tumor vaccines against neoantigens mainly encompass peptides, DNA, RNA, and dendritic cells, which are extremely specific to individual patients. Due to the high immunogenicity of neoantigens, tumor vaccines could activate and expand antigen-specific CD4+ and CD8+ T cells to intensify anti-tumor immunity. Herein, we introduce the origin and prediction of neoantigens and compare the advantages and disadvantages of multiple types of neoantigen vaccines. Besides, we review the immunizations and the current clinical research status in neoantigen vaccines, and outline strategies for enhancing the efficacy of neoantigen vaccines. Finally, we present the challenges facing the application of neoantigens.

Abstract P010: Antigen dominance hierarchies shape CD8 T cell phenotypes and immunotherapy response in tumors

Abstract CD8 T cell responses against different tumor neoantigens occur simultaneously, yet it is unclear whether they interact to potentiate or antagonize the overall anti-tumor response. In a genetically engineered mouse model of lung adenocarcinoma, we find that antigen dominance hierarchies are established in tumors wherein the antigen that most stably binds MHC dominates the CD8 T cell response. This negatively impacts the response to subdominant antigens, suppressing T cell expansion, differentiation and effector function; a phenotype that is reversed when the dominant antigen is removed. Intriguingly, the subdominant response is also enriched for a TCF1+ progenitor cell phenotype that has been correlated with response to immune checkpoint blockade (ICB) therapy. However, we find that the subdominant response does not preferentially benefit from ICB due to predominance of a dysfunctional subset of TCF1+ cells marked by CCR6 expression and differentiation to a Tc17 phenotype. CCR6+ TCF1+ cells are also found broadly across human cancers and do not correlate with patient response to ICB. This subset appears to be derived from poor T cell receptor stimulation, due to competition of T cells for good interactions with antigen presenting cells. Vaccination eliminates CCR6+ TCF1+ cells and disrupts the antigen dominance hierarchy, preferentially expanding the subdominant CD8 T cell response in tumors. Overall enrichment of TCF1+ cells is maintained amongst the subdominant response post-vaccination and current studies are exploring whether this promotes more durable tumor control or better response to ICB. These findings provide strong rationale for evaluating the relative response to high versus low pMHC stability antigens in clinical trials of pooled neoantigen vaccines, where low stability, subdominant antigens may contribute more to tumor control than previously realized. Citation Format: Megan L. Burger, Amanda M. Cruz, Grace E. Crossland, Giorgio Gaglia, Cecily C. Ritch, Sarah E. Blatt, Arjun Bhutkar, Sara Z. Tavana, Sandro Santagata, Tyler Jacks. Antigen dominance hierarchies shape CD8 T cell phenotypes and immunotherapy response in tumors [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P010.

Personalized neoantigen vaccine prevents postoperative recurrence in hepatocellular carcinoma patients with vascular invasion

BackgroundClinically, prophylactic anti-recurrence treatments for hepatocellular carcinoma (HCC) patients after radical surgery are extremely limited. Neoantigen based vaccine can generate robust anti-tumor immune response in several solid tumors but whether it could induce anti-tumor immune response in HCC and serve as a safe and effective prophylactic strategy for preventing postoperative HCC recurrence still remain largely unclear.MethodsPersonalized neoantigen vaccine was designed and immunized for 10 HCC patients with high risk of postoperative recurrence in a prime-boost schedule. The safety and immune response were assessed through adverse events, tissue sequencing, ELISpot, TCR sequencing. The clinical response was evaluated by recurrence-free survival (RFS) and personalized circulating tumor DNA (ctDNA) sequencing.ResultsIn the 10 enrolled patients, no obvious adverse events were observed during neoantigen vaccinations. Until the deadline of clinical trial, 8 of 10 patients were confirmed with clinical relapse by imaging, the other 2 patients remained relapse-free. From receiving first neoantigen vaccination, the median RFS of 10 patients were 7.4 months. Among 7 patients received all planned neoantigen vaccinations, 5 of them demonstrated neoantigen-induced T cell responses and have significantly longer RFS after radical surgery than other 5 patients without responsive neoantigens or only with prime vaccination and propensity scores matching control patients (p = 0.035). Moreover, tracking personalized neoantigen mutations in ctDNA could provide real-time evaluation of clinical response in HCC patients during neoantigen vaccination and follow up.ConclusionPersonalized neoantigen vaccine is proved as a safe, feasible and effective strategy for HCC anti-recurrence, and its progression could be sensitively monitored by corresponding neoantigen mutations in ctDNA, and thus provided solid information for individualized medicine in HCC.Trial registrationThis study was registered at Chinese Clinical Trial Registry; Registration number: ChiCTR1900020990.

Editors' Selections from Relevant Scientific Publications.

Editors' Selections from Relevant Scientific Publications.

A Personalized Neoantigen Vaccine in Combination with Platinum-Based Chemotherapy Induces a T-Cell Response Coinciding with a Complete Response in Endometrial Carcinoma.

Simple SummaryWe investigated the feasibility and immunogenicity of an autologous Dendritic Cell (DC) vaccine pulsed with peptide neoantigens in combination with a standard of care regimen. The vaccine program took place in a serous endometrial mismatch repair (MMR) deficiency setting. We demonstrate for the first time the feasibility of producing a peptide DC vaccine in endometrial carcinoma. The safety and immunogenicity of this personalized vaccine was demonstrated by the detection of polyfunctional and durable T-cell responses.Endometrial cancer (EC) is a common gynecological malignancy and the fourth most common malignancy in European and North American women. Amongst EC, the advanced serous, p53-mutated, and pMMR subtypes have the highest risk of relapse despite optimal standard of care therapy. At present, there is no standard of care maintenance treatment to prevent relapse among these high-risk patients. Vaccines are a form of immunotherapy that can potentially increase the immunogenicity of pMMR, serous, and p53-mutated tumors to render them responsive to check point inhibitor-based immunotherapy. We demonstrate, for the first time, the feasibility of generating a personalized dendritic cell vaccine pulsed with peptide neoantigens in a patient with pMMR, p53-mutated, and serous endometrial adenocarcinoma (SEC). The personalized vaccine was administered in combination with systemic chemotherapy to treat an inoperable metastatic recurrence. This treatment association demonstrated the safety and immunogenicity of the personalized dendritic cell vaccine. Interestingly, a complete oncological response was obtained with respect to both radiological assessment and the tumor marker CA-125.

TMOD-14. CONJOINED CLASS I AND II EPITOPES ENHANCE NEOANTIGEN-TARGETED ACTIVE IMMUNOTHERAPY

Abstract INTRODUCTION Cancer vaccines involve the administration of tumor-associated antigens into the host to generate anti-tumor T cell responses. Glioblastoma (GBM) is a disease with poor prognosis. GBM has a limited number of immunotherapeutic targets due to low mutational load, and is also highly heterogeneous; targeting a single antigen leads to antigen escape and tumor growth. METHODS VMDK mice were subcutaneously implanted with 750,000 SMA560 cells and on days 1 and 8 post implantation, mice were treated with 15 nmol of the universal helper epitope, P30, conjoined to the MHCI-restricted neoepitopes Odc1MHCI-P30 or Topbp1MHCI-P30. Human CD27 (hCD27) transgenic mice were intracranially implanted with CT2A-Odc1, followed by anti-CD27 and 15 nmol of Odc1MHCI-P30. B16.OVA or B16.F10 tumor cells were intracranially implanted in hCD27 mice and received SIINFEKL-P30 or Trp2-P30 conjoined peptides. Tumor growth, survival, or IFNγ secretion of splenic or tumor-infiltrating cells was assessed. RESULTS Unlike Odc1MHCI mixed with P30, conjoined Odc1MHCI-P30 had equivalent immunogenicity and anti-tumor efficacy to that observed with native long Odc1 peptide. Native long peptide of Topbp1 did not elicit an antitumor response, yet Topbp1MHCI-P30 caused an increase in numbers of IFNγ-secreting splenocytes and a decrease in tumor growth and similar to that seen with Odc1MHCI-P30 . Anti-CD27 treatment significantly increased numbers of IFNγ secreting splenocytes in Odc1MHCI-P30 vaccinated hCD27 mice, and the use of anti-CD27 with Odc1MHCI-P30 achieved long-term survival in 90% of tumor bearing hCD27 mice. Anti-CD27 synergized with SIINFEKL-P30 and Trp2-P30 to significantly improve survival after administration of these peptides. CONCLUSIONS Our work shows that poorly immunogenic neoantigens can be conjoined to P30 and used to generate an anti-tumor response in mouse models of GBM, and anti-tumor responses of conjoined peptides can be enhanced with anti-CD27 treatment. Together, these data demonstrate the efficacy of neoantigen vaccines for the treatment of heterogeneous GBM.

Maximizing cancer therapy via complementary mechanisms of immune activation: PD-1 blockade, neoantigen vaccination, and Tregs depletion

BackgroundA number of different immune pathways are involved in the effective killing of cancer cells, collectively named as the ‘Cancer Immunity Cycle’. Anti-PD-1 checkpoint blockade (CPB) therapy is active on...