Tumor-specific T-cell Responses Research Articles

IL-13Rα2/TGF-β bispecific CAR-T cells counter TGF-β-mediated immune suppression and potentiate anti-tumor responses in glioblastoma.

Chimeric antigen receptor (CAR)-T cell therapies targeting glioblastoma (GBM)-associated antigens such as interleukin-13 receptor subunit alpha-2 (IL-13Rα2) have achieved limited clinical efficacy to date, in part due to an immunosuppressive tumor microenvironment (TME) characterized by inhibitory molecules such as transforming growth factor-beta (TGF-β). The aim of this study was to engineer more potent GBM-targeting CAR-T cells by countering TGF-β-mediated immune suppression in the TME. We engineered a single-chain, bispecific CAR targeting IL-13Rα2 and TGF-β, which programs tumor-specific T cells to convert TGF-β from an immunosuppressant to an immunostimulant. Bispecific IL-13Rα2/TGF-β CAR-T cells were evaluated for efficacy and safety against both patient-derived GBM xenografts and syngeneic models of murine glioma. Treatment with IL-13Rα2/TGF-β CAR-T cells leads to greater T-cell infiltration and reduced suppressive myeloid cell presence in the tumor-bearing brain compared to treatment with conventional IL-13Rα2 CAR-T cells, resulting in improved survival in both patient-derived GBM xenografts and syngeneic models of murine glioma. Our findings demonstrate that by reprogramming tumor-specific T-cell responses to TGF-β, bispecific IL-13Rα2/TGF-β CAR-T cells resist and remodel the immunosuppressive TME to drive potent anti-tumor responses in GBM.

Immune mechanisms and predictive biomarkers related to neoadjuvant immunotherapy response in stage III melanoma

The treatment for stage III melanoma has advanced significantly, nevertheless, a substantial proportion of patients experience relapse. Neoadjuvant immune checkpoint blockade has emerged as a promising approach, allowing early micrometastatic disease treatment, reduction of tumor burden before surgery, and enhanced tumor-specific T-cell responses. However, not all patients respond to treatment, highlighting the need for understanding immune mechanisms behind failure and identification of predictive markers. Here we performed a robust evaluation of systemic and tumoral immune profiles in a well-defined cohort of advanced melanoma patients treated with immune checkpoint inhibitors. Elevated CTACK and CXCL9 chemokines pre-treatment suggested their potential as predictive tools for treatment response. Furthermore, CD95 expression in CD8+ T lymphocytes surfaced as a favorable prognostic indicator, while PD-1, CD161, and PD-L2 exhibited correlations with worst outcomes. These findings shed light on the intricate interplay between immune markers and melanoma response to neoadjuvant immune checkpoint therapy, offering insights into personalized treatment strategies.

Ultrasound-visible engineered bacteria for tumor chemo-immunotherapy

Our previous work developed acoustic response bacteria, which enable the precise tuning of transgene expression through ultrasound. However, it is still difficult to visualize these bacteria in order to guide the sound wave to precisely irradiate them. Here, we develop ultrasound-visible engineered bacteria and chemically modify them with doxorubicin (DOX) on their surfaces. These engineered bacteria (Ec@DIG-GVs) can produce gas vesicles (GVs), providing a real-time imaging guide for remote hyperthermia high-intensity focused ultrasound (hHIFU) to induce the expression of the interferon (IFN)-γ gene. The production of IFN-γ can kill tumor cells, induce macrophage polarization from the M2 to the M1 phenotype, and promote the maturation of dendritic cells. DOX can be released in the acidic tumor microenvironment, resulting in immunogenic cell death of tumor cells. The concurrent effects of IFN-γ and DOX activate a tumor-specific Tcell response, producing the synergistic anti-tumor efficacy. Our study provides a promising strategy for bacteria-mediated tumor chemo-immunotherapy.

FusionVAC22_01: a phase I clinical trial evaluating a DNAJB1-PRKACA fusion transcript-based peptide vaccine combined with immune checkpoint inhibition for fibrolamellar hepatocellular carcinoma and other tumor entities carrying the oncogenic driver fusion.

EU CT Number: 2022-502869-17-01 and ClinicalTrials.gov Registry (NCT05937295).

Abstract 3907: Novel public and tumor-wide neoantigens arising from clonal aberrant splicing events drive tumor-specific T-cell responses across diverse cancer types

Abstract BACKGROUND: Immunotherapy in gliomas is limited by intratumor heterogeneity (ITH) and low mutational burden. We developed a novel comprehensive in silico pipeline for detecting tumor-specific splicing events (neojunctions), and across multiple cancer types, we successfully identified a new class of tumor-wide, public, alternatively spliced neoantigens (ASNs) that elicit CD8+ T-cell-mediated immune responses. METHODS: Our pipeline identified recurring public neojunctions expressed in TCGA RNA-seq (positive sample rate (PSR) > 10%) and not in GTEx normal tissue RNA-seq data (PSR < 1%) across ten cancer types. To characterize tumor-wide neojunctions, we utilized available multi-site RNA sequencing across diverse cancer types. With gliomas, our in-house dataset comprised of 56 patients with approximately 10 maximally-distanced intratumoral biopsy sites per patient (n=535). Tumor-wide public neojunction expression was subsequently validated in RNA-sequencing and mass spectrometry (MS) data from patient-derived cell lines (n=68) and samples (n=447). Two independent algorithms then predicted peptide processing likelihood and HLA-binding affinity of ASN candidates. TCRs identified by in vitro sensitization (IVS) of donor-derived CD8+ T-cells followed by 10x VDJ scRNA-seq, were transduced into CD8+ T-cells and co-cultured with tumor cells to evaluate TCR functionality and cytotoxicity. RESULTS: Pan-cancer analysis identified large subsets of neojunctions that were interpatiently and intratumorally conserved. Our glioma-specific analysis identified 789 public neojunctions, and 8 ASNs were validated in transcriptomic and proteomic glioma data and predicted to be presented by HLA-A*02:01 with high confidence. IVS and subsequent 10x VDJ scRNA-seq on expanded PBMC-derived CD8+ populations cultured against ASN-pulsed dendritic cells identified TCR clonotypes reactive against neojunctions in RPL22 (n=7) and GNAS (n=1), the latter being highly intratumorally-conserved (detected in > 90% of spatially-mapped biopsies in 17/56 patients (26.78%)). TCR-transduced T-cells demonstrated recognition and immunogenic activation against endogenously processed and presented neoantigens in both pan-cancer cell lines and transfected COS7 cells and cytotoxicity against glioma cell lines. Pan-cancer analysis revealed the detection of both neojunctions in various tumor types beyond gliomas, with the GNAS neojunction notably found tumor-wide in mesothelioma, prostate cancer, and liver hepatocellular carcinoma spatial data. CONCLUSION: Our unique integrative pipeline identified a novel class public tumor-wide splice-derived neoantigen candidates and ASN-specific TCRs, offering a promising off-the-shelf immunotherapy approach for diverse cancer types and tackling the critical challenge of ITH in immunotherapy resistance. Citation Format: Darwin Kwok, Nicholas O. Stevers, Takahide Nejo, Lee H. Chen, Inaki Etxeberria, Jangham Jung, Kaori Okada, Maggie Colton Cove, Senthilnath Lakshmanachetty, Marco Gallus, Abhilash Barpanda, Chibo Hong, Gary KL Chan, Samuel H. Wu, Emilio Ramos, Akane Yamamichi, Jerry YZ Liu, Payal Watchmaker, Hirokazu Ogino, Atsuro Saijo, Aidan Du, Nadia Grishanina, James Woo, Aaron Diaz, Susan M. Chang, Joanna J. Phillips, Arun P. Wiita, Christopher A. Klebanoff, Joseph F. Costello, Hideho Okada. Novel public and tumor-wide neoantigens arising from clonal aberrant splicing events drive tumor-specific T-cell responses across diverse cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3907.

Immunospot Assessment of T-Cell Responses in Preclinical Tumor Models with Undefined Target Antigens.

Assessment of functional tumor-specific T-cell responses in preclinical tumor models represents an important tool for successful translation of new immunotherapies to clinics. Usually, it requires a known tumor antigen target. Here, we describe the method to detect tumor-specific T cell after immunotherapies without a known antigen. Splenocytes, lymph node immune cells, or PBMCs are isolated from treated mice and stimulated with relevant tumor cells ex vivo before immunospot analysis of Granzyme B and interferon γ-positive T cells. The method is especially valuable for monitoring tumor-specific T cells after vaccination with various whole tumor vaccines or after in situ vaccination and other antigen agnostic immunotherapies, where no specific antigens are used.

Abstract C080: Ultra-high concentration nitric oxide (UNO) enhances anti-CTLA-4 treatment activity and induces a durable anti-tumor immune response

Abstract Background: CTLA-4 blockade is a highly effective therapeutic modality but only in a subset of cancer patients. We previously demonstrated that intratumoral administration of ultra-high concentration nitric oxide (UNO) augmented response to the immune checkpoint inhibitor, anti-mPD-1. Specifically, more than half of the mice treated with 10-minutes UNO (50,000 ppm) and anti-mPD-1 were primary and secondary tumor-free at Day 100 post-UNO treatment (vs 25% of control mice treated with anti-mPD-1 alone). In addition, the combination of UNO and anti-mCTLA-4 assessed in an immunocompetent breast cancer model (4T1) demonstrated prolonged survival in mice compared to single-agent anti-mCTLA-4. In CT26 and 4T1 mice, the immunodominant AH-1 antigen is associated with anti-tumor immune response. In this study, we assessed the systemic levels of CD8+ T-cells recognizing the AH-1 antigen following UNO treatment and the association with anti-tumor response. Methods: Here we explored the effects of UNO treatment in combination with anti-mCTLA-4 therapy. Colon carcinoma (CT26) tumor-bearing mice were treated with intra-tumoral 100,000 ppm UNO for 5 minutes in combination with 5 mg/kg (IP) anti-mCTLA-4. Effects on tumor growth and anti-tumor immune response were assessed. AH-1 specific CD8+ T cells were quantified by flow cytometry. Results: Combining 100,000 ppm UNO with anti-mCTLA4 in CT26 tumor-bearing mice resulted in considerable growth delay and regression of treated tumors. Furthermore, the combination induced a strong systemic response that led to the rejection of a distant metastasis-like tumor inoculated on the contralateral flank. Specifically, at Day 7 post-treatment, all UNO treated mice exhibited tumor-specific CD8+ T-cells in the blood and to a higher degree than in untreated mice. Moreover, systemic levels of tumor-specific CD8+ T-cells were higher in mice treated with the combination of UNO and anti-mCTLA4 compared to mice treated with monotherapy anti-mCTLA-4, indicating an increase in immune surveillance following UNO treatment. Finally, cured mice treated with combination therapy displayed higher systemic levels of antigen-specific CD8+ T-cells compared to untreated or naïve mice. Conclusion: UNO stimulates a higher tumor-specific T-cell response than anti-mCTLA-4 and synergizes with this drug to generate an even more significant targeted immune response. Citation Format: Yogev Sela, Matan Goldshtein, Jedidiah M. Monson, Hila Confino, Amir Avniel, Mark D. Pegram, Selena Chaisson. Ultra-high concentration nitric oxide (UNO) enhances anti-CTLA-4 treatment activity and induces a durable anti-tumor immune response [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C080.

MP0533, a CD3-Engaging Darpin Targeting CD33, CD123, and CD70 in Patients with Relapsed/Refractory AML or MDS/AML: Preliminary Results of a Phase 1/2a Study

BACKGROUND: The development of targeted immunotherapy for acute myeloid leukemia (AML) is challenging due to the clonal heterogeneity of the disease and the lack of single AML-specific target antigens. MP0533 is a multi-specific, half-life extended CD3-engaging DARPin (Designed Ankyrin Repeat Protein). It simultaneously targets CD33, CD123, and CD70, thereby enabling avidity-driven T cell-mediated killing of leukemic stem cells (LSCs) and malignant blast cells known to co-express these targets. MP0533's affinity to each target is tuned to preferentially kill malignant cells which co-express at least two of these three antigens, while preserving a therapeutic window towards healthy cells. MP0533 was shown to induce a tumor-specific endogenous T-cell response in ex vivo samples from AML patients and led to T-cell-mediated eradication of tumors in AML xenograft mouse models, with limited cytokine release or other serious adverse reactions (Bianchi et al., Blood 2022;140[Suppl 1]:2251-2). Herein, we present early observations of the first three MP0533 dose-escalation regimens (DR) of the ongoing first-in-human, multicenter, single-arm, open-label, phase 1/2a study. METHODS: The objectives of this ongoing trial are to evaluate the safety/tolerability, pharmacokinetics (PK), and pharmacodynamics, as well as preliminary antileukemic activity of MP0533 monotherapy in patients with relapsed/refractory (R/R) AML or myelodysplastic syndrome (MDS)/AML (NCT05673057). Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2, and a life expectancy of ≥12 weeks are eligible. Up to 45 patients will be enrolled in the dose-escalation part of the trial. Patients receive MP0533 once per week starting at day 15 after a stepwise dose increase on days 1, 5, and 8, and until disease progression or unacceptable toxicity. One cycle corresponds to 28 days. DR escalation of MP0533 is guided by two Bayesian logistic regression models estimating the joint probability of cytokine release syndrome (CRS) and non-CRS dose-limiting toxicities (DLTs). Bone marrow examinations are performed at weeks 4, 8, and 12. Responses are determined using 2022 European LeukemiaNet (ELN) criteria with an assessment of hematologic improvement. Treatment-emergent adverse events (TEAEs) are assessed according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v5.0. RESULTS: As of data cut-off (20 July 2023), 5 patients received ≥5 infusions of MP0533 across 3 DRs preceded by step-up dosing (1 patient each at DR 1 and DR 2, respectively, and 3 patients at DR 3), including 2 women and 3 men. The median age at enrollment was 79 years (range 68-81). All patients had adverse risk mutations. Patients received a median number of 1 prior antileukemic therapy line (range 1-2) and on average 2 cycles of MP0533 treatment (range 1-3). To date, one patient with a TP53 mutation achieved a morphologic leukemia-free state after 8 weeks and complete remission with incomplete hematologic recovery (CRi) after 12 weeks of treatment with DR 3. No DLTs have been observed in any DR so far. TEAEs considered to be related to MP0533 were Grade 2 infusion-related reaction (2 patients), Grade 1 CRS (2 patients), and Grade 1 diarrhea and fatigue (1 patient). No Grade ≥3 drug-related TEAEs were reported. The reported TEAEs (Figure) reflected the patients' disease course. Preliminary PK results up to DR 3 confirmed that all patients were exposed to MP0533 and exposure levels were broadly aligned with PK/PD model predictions of MP0533 in serum. CONCLUSION: The results of this ongoing phase 1/2a study indicated an acceptable safety profile of MP0533 monotherapy in 5 patients up to DR 3 with weekly infusions. Preliminary response data are encouraging, with one response observed in 1 of 2 patients evaluable for response in DR 3 to date.

A clinical trial of therapeutic vaccination in lymphoma with serial tumor sampling and single-cell analysis

AbstractIn situ vaccination (ISV) triggers an immune response to tumor-associated antigens at 1 tumor site, which can then tackle the disease throughout the body. Here, we report clinical and biological results of a phase 1/2 ISV trial in patients with low-grade lymphoma, combining an intratumoral toll-like receptor 9 (TLR9) agonist with local low-dose radiation and ibrutinib (an inhibitor of B- and T-cell kinases). Adverse events were predominately low grade. The overall response rate was 50%, including 1 complete response. All patients experienced tumor reduction at distant sites. Single-cell analyses of serial fine needle aspirates from injected and uninjected tumors revealed correlates of clinical response, such as lower CD47 and higher major histocompatibility complex class II expression on tumor cells, enhanced T-cell and natural killer cell effector function, and reduced immune suppression from transforming growth factor β and inhibitory T regulatory 1 cells. Although changes at the local injected site were more pronounced, changes at distant uninjected sites were more often associated with clinical responses. Functional immune response assays and tracking of T-cell receptor sequences provided evidence of treatment-induced tumor-specific T-cell responses. Induction of immune effectors and reversal of negative regulators were both important in producing clinically meaningful tumor responses. The trial was registered at www.clinicaltrials.gov as #NCT02927964.

Tumor vaccine based on extracellular vesicles derived from γδ-T cells exerts dual antitumor activities.

γδ-T cells are innate-like T cells with dual antitumor activities. They can directly eradicate tumor cells and function as immunostimulatory cells to promote antitumor immunity. Previous studies have demonstrated that small extracellular vesicles (EVs) derived from γδ-T cells (γδ-T-EVs) inherited the dual antitumor activities from their parental cells. However, it remains unknown whether γδ-T-EVs can be designed as tumors vaccine to improve therapeutic efficacy. Here, we found that γδ-T-EVs had immune adjuvant effects on antigen-presenting cells, as revealed by enhanced expression of antigen-presenting and co-stimulatory molecules, secretion of pro-inflammatory cytokines and antigen-presenting ability of DCs after γδ-T-EVs treatment. The γδ-T-EVs-based vaccine was designed by loading tumor-associated antigens (TAAs) into γδ-T-EVs. Compared with γδ-T-EVs, the γδ-T-EVs-based vaccine effectively promoted more tumor-specific T-cell responses. In addition, the vaccine regimen preserved direct antitumor effects and induced tumor cell apoptosis. Interestingly, the allogeneic γδ-T-EVs-based vaccine showed comparable preventive and therapeutic antitumor effects to their autologous counterparts, indicating a better way of centralization and standardization in clinical practice. Furthermore, the allogeneic γδ-T-EVs-based vaccine displayed advantages over the DC-EVs-based vaccine through their dual antitumor activities. This study provides a proof-of-concept for using the allogeneic γδ-T-EVs-based vaccine in cancer control.

Homeostatic PD-1 signaling restrains EOMES-dependent oligoclonal expansion of liver-resident CD8 T cells

The co-inhibitory programmed death (PD)-1 signaling pathway plays a major role in the context of tumor-specific Tcell responses. Conversely, it also contributes to the maintenance of peripheral tolerance, as patients receiving anti-PD-1 treatment are prone to developing immune-related adverse events. Yet, the physiological role of the PD-1/PDL-1 axis in Tcell homeostasis is still poorly understood. Herein, we show that under steady-state conditions, the absence of PD-1 signaling led to a preferential expansion of CD8+ Tcells in the liver. These cells exhibit an oligoclonal Tcell receptor (TCR) repertoire and a terminally differentiated exhaustion profile. The transcription factor EOMES is required for the clonal expansion and acquisition of this differentiation program. Finally, single-cell transcriptomics coupled with TCR repertoire analysis support the notion that these cells arise locally from liver-resident memory CD8+ Tcells. Overall, we show a role for PD-1 signaling in liver memory Tcell homeostasis.

A multi-targeted T-cell engagement of PD1-resistant colorectal cancer cells via delivery of glycopeptide conjugates.

e14571 Background: Glycan-based cancer immunotherapies are novel therapeutic strategies that use the pivotal role of aberrant glycosylation patterns in cancer progression. Targeting hybrid epitopes consisting of altered glycans and carrier peptides enhances the efficacy and specificity of the anti-tumor immune response. Here, we exploit ensembles of glycopeptide conjugates to steer a multi-targeted yet tumor-specific T-cell response, a technology we call GLAAD (glycopeptides with adjuvant and tumor-associated antigen delivery). By inducing T cells that recognize and eliminate tumor cells and promoting their antigenicity in a therapeutic setting, we show the potential of our GLAAD candidate GNU-101 to overcome the transient and heterogeneous responses frequently observed with traditional immunotherapies. Methods: Using the MC38 syngeneic mouse model of colorectal cancer (CRC) in a therapeutic setting, we tested whether GNU-101 reduces tumor burden when orally administered alone or combined with immune checkpoint inhibitors (ICI). On day 0, 20 C57/BL6J mice were injected subcutaneously with MC38 CRC cells in each flank. On day 6, mice were supplemented with 3% GNU-101 in the drinking water, while control mice received normal drinking water. On days 6, 9, 12, and 15, half of the mice in each group received an anti-PD1 antibody (aPD1), while the others received isotype control. On day 16, the mice were sacrificed. Results: In this therapeutic setting, a standalone therapy of GNU-101 successfully reduced tumor growth as demonstrated by a statistically significant reduction in both tumor volume and weight. As expected, the aPD1 therapy had only a non-significant effect on tumor growth. Remarkably, its efficacy was improved when combined with GNU-101, leading to a statistically significant reduction of >90% in tumor volume and weight. The analysis of the immune cell population in the tumor microenvironment revealed the activation of CD8 T cells and a reduction of immunosuppressive signals, which likely mediates the anti-tumor efficacy of GNU-101. This was obvious by a higher abundance of CD8 T cells producing IFNγ and secreting granzyme B & perforin and, conversely, lower amounts of Tim3+ CD8 T cells and regulatory T cells (FoxP3+ CD4 T cells) found in mice treated with GNU-101 vs control mice. Conclusions: We demonstrate the immunomodulatory and therapeutic potential of GNU-101 in a pre-clinical mouse study in which the growth of established tumors was significantly reduced, either as a standalone therapy or in combination with existing treatment. By specifically promoting anti-cancer CD8+ T cells while reducing immunosuppressive signals, this easy-to-administer glycopeptide has the potential to create the conditions for long-term cancer control and improve treatment outcomes in cancer that are frequently resistant to immunotherapy, such as many epithelial cancers.

Acute Influenza Infection Promotes Lung Tumor Growth by Reprogramming the Tumor Microenvironment.

One billion people worldwide get flu every year, including patients with non-small cell lung cancer (NSCLC). However, the impact of acute influenza A virus (IAV) infection on the composition of the tumor microenvironment (TME) and the clinical outcome of patients with NSCLC is largely unknown. We set out to understand how IAV load impacts cancer growth and modifies cellular and molecular players in the TME. Herein, we report that IAV can infect both tumor and immune cells, resulting in a long-term protumoral effect in tumor-bearing mice. Mechanistically, IAV impaired tumor-specific T-cell responses, led to the exhaustion of memory CD8+ T cells and induced PD-L1 expression on tumor cells. IAV infection modulated the transcriptomic profile of the TME, fine-tuning it toward immunosuppression, carcinogenesis, and lipid and drug metabolism. Consistent with these data, the transcriptional module induced by IAV infection in tumor cells in tumor-bearing mice was also found in human patients with lung adenocarcinoma and correlated with poor overall survival. In conclusion, we found that IAV infection worsened lung tumor progression by reprogramming the TME toward a more aggressive state.

Phase I trial of perioperative chemotherapy plus immunotherapy in localized esophageal and gastroesophageal adenocarcinoma.

400 Background: The management of esophageal cancer (EC) and gastroesophageal junction (GEJ) adenocarcinoma has focused on perioperative approaches that aim to increase pathological complete response (pathCR) rates, decrease or delay metastases, improve resectability, and enhance overall survival. Atezolizumab is a humanized immunoglobulin (Ig) G1 monoclonal antibody that targets PD-L1 and inhibits the interaction between PD-L1 and its receptors, PD-1, and B7-1, both of which function as inhibitory receptors expressed on T-cells. Therapeutic binding of PD-L1 by atezolizumab has been shown to enhance the magnitude and quality of tumor-specific T-cell responses, resulting in improved anti-tumor activity. The use of immunotherapy in combination with chemotherapy in the perioperative setting may improve the response rate in patients with localized EC and GEJ adenocarcinoma. Methods: We conducted a phase I study evaluating the efficacy and safety of atezolizumab in combination with oxaliplatin and 5-fluorouracil (modified FOLFOX) therapy in the perioperative setting. Patients with T1N1 or T2-3 (any N) localized EC and GEJ type I or II adenocarcinoma were included. Treatment consisted of oxaliplatin (85 mg/m2 over 2 hours on days 1 and 15) and 5-fluorouracil (2.4g/m2 (over 48 hours) via infusion pump on days 1 and 15) followed by atezolizumab (840 mg via IV on days 1 and 15) of each 28-day cycle for a total of 6 doses followed by surgery and subsequently postoperative atezolizumab 1200 mg IV on Day 1 of each 21-day cycle for 8 more doses. Results: From April 2019 to November 2020, 20 patients were enrolled with a median age of 61 years old and baseline TNM staging: T2-3N0 (n=8), T3N1-N2 (n=10), and T3N3-NX (n=2). Eighteen patients underwent surgery; two patients (11%, 95% credible interval = 1-28%) achieved the primary efficacy objective (pathCR defined as pathological T0N0), and two additional patients (11%) had near complete pathCR with <1% viable tumor. Fifteen patients (83%) had R0 resection. Grade 4 treatment-related events occurred in 2 patients and grade 2 and 3 treatment related events occurred in 9 and 7 patients respectively. No treatment-related events leading to discontinuation of therapy or treatment-related deaths occurred. Forty-five percent of the patients died and 44% of patients had recurrence with a median disease-free survival of 29 months. Conclusions: Results indicate that atezolizumab in combination with oxaliplatin and 5-fluorouracil has an acceptable safety profile providing high tumor regression. This trial supports further research of atezolizumab for the treatment of patients with localized EC and GEJ in the perioperative setting. Clinical trial information: NCT03784326 .

Use of an Allogeneic Leukemia-Derived Dendritic Cell Vaccine in MRD+ AML-Patients Results in MRD Conversion, Improved Relapse-Free Survival and Vaccine Induced Immune Responses to Tumor Antigens

Background. Maintenance therapy in AML patients with measurable residual disease (MRD) remains challenging. Immunotherapy could be an effective way to induce durable disease control. This phase II study aims to show efficacy of priming the immune system, using an allogenic leukemia-derived dendritic cell vaccine (DCP-001), to induce an effective anti-leukemic response to control or kill remaining malignant cells (ADVANCE-II, Clintrials.gov: NCT03697707). Methods. A total of 20 evaluable AML patients in first complete remission (CR1) with MRD positivity and ineligible for HSCT received 4 biweekly doses of 25e6 or 50e6 cells per intradermal vaccination (cells/vc) and 2 doses as boosts at week 14 and 18 of 10e6 cells/vc. MRD, as primary endpoint, was assessed at baseline, week 14, 20 and 32 by flow cytometry and/or molecular analyses. Evaluation of secondary endpoints relapse-free (RFS) and overall survival (OS) was done at data cut-off (18th July 2022). Peripheral blood samples were taken before and during treatment for analysis of vaccine induced responses as measured by IFNγ ELISPOT and general immune profiles by flow cytometry using a 40-marker panel. Results. Patients aged 34-79 (median 60y) had a cytogenetic risk status assessed of 4 better, 15 intermediate and 1 poor-risk, with mutations in NPM1 (n=10), CBFB-MYH11 (n=4), IDH2 (n=2), RUNX1-RUNX1T1 (n=2), TP53 (n=1) and CEBPA (n=1). All 20 patients have received 4 initial vaccinations, 17 patients received all booster vaccinations and 1 patient received one booster. No serious adverse events (AE) or severe AE (grade 3 or higher) related to the treatment have been reported. Related AEs are mainly injection site reactions, such as redness, warmth and swelling, occurring within 48 hours after intradermal administration. To date, median RFS and OS have not yet been reached (Figure 1), with a median follow up period of 15.4 (range 6.6- 16.8) months for the entire study population. Estimated RFS and OS at 6 months is 83.9% (range 64-94%) and 97% (range 79-99%), respectively. Estimated RFS and OS at 12 months is 70% (range 48-85%) and 87% (67-95%), respectively. MRD response (conversion or >10-fold decrease of MRD) was observed in 7 patients: 5 patients converted to negative and 2 showed a MRD decrease. Responses were observed within 14-20 weeks and durable in 4 out of 5 patients, remaining MRD negative up to week 32. Seven patients remained in CR with stable MRD levels and 6 patients relapsed before week 32. Three patients with stable MRD became eligible for HSCT during study and were transplanted successfully. Immune responses were observed to tumor associated antigens expressed by DCP-001; WT1, RHAMM and PRAME, with specific vaccine induced responses (VIR) in the majority of patients (17/20) and highest number of VIR per antigen observed in patients with MRD responses (Figure 2). Differences in immune profiles at baseline were observed; relapsed patients had a high number of CD8RO+ cells, in particular CD8 CM. On the contrary, MRD responders had the highest level of CD8RA+ cells at baseline, with CD8 EMRA cells at the highest level. Patients with stable MRD had comparable, but slightly lower CD8RO+ levels than MRD responders. Conclusion/discussion. Vaccination with DCP-001 resulted in durable MRD responses with five patients converting to MRD negativity, remaining relapse-free and alive during follow up. This translates in promising survival data with the median RFS for the full patient population not reached to date, at a median FU time of 15.4 months. Highest level of vaccine-induced T-cell responses to leukemia specific antigens were detected in MRD responders. Baseline levels of CD8 memory profiles were markedly different in MRD responders, which might be indicative that lower number of memory cells, and thus especially higher number of CD8 EMRA could reflect the ability to induce a tumor specific cytotoxic T-cell response after vaccination. Relapse on study was limited, with an estimated RFS at 6 months of 83.7%, which is higher than expected for this MRD+ AML patient population, which would be around 45% as shown for placebo-treated patients from a recent phase III study in a similar patient population (Quazar AML001). Immunotherapy with DCP-001 as AML maintenance therapy is safe and effective in triggering immune responses and converting patients from MRD positive to MRD negative, leading to promising relapse-free survival. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A therapeutic DC vaccine with maintained immunological activity exhibits robust anti-tumor efficacy.

Dendritic cells (DCs) vaccines are a major focus of future anti-tumor immunotherapy for their pivotal role in eliciting reactive tumor-specific T-cell responses. Tumor cell-mediated DCs (TC-DC) activation and tumor antigen-mediated DCs (TA-DC) activation are two conventional modes of DC vaccine construction in clinical studies. The former physiologically mimicks the tumor identification and rejection, significantly contributing to DC-based immune recognition and migration towards the complexed tumor microenvironment (TME). However, as immunosuppressive molecules may exist in TME, these TC-DC are generally characterized with aberrant lipid accumulation and inositol-requiring kinase 1α (IRE1α)-X-box binding protein 1 (XBP1) hyperactivation, which is provoked by overwhelming oxidative stress and endoplasmic reticulum (ER) stress, resulting in TC-DC malfunction. Oppositely, without contacting immunosuppressive TME, TA-DC vaccines perform better in T-cell priming and lymph nodes (LNs) homing, but are relatively weak in TME infiltration and identification. Herein, we prepared a KIRA6-loaded α-Tocopherol nanoemulsion (KT-NE), which simultaneously ameliorated oxidative stress and ER stress in the dysfunctional lipid-laden TC-DC. The TC-DC treated by KT-NE could maintain immunological activity, simultaneously, exhibited satisfactory chemotaxis towards LNs and tumor sites in vivo, and effectively suppressed malignant progression by unleashing activated tumor-reactive T cells. This study generated a new DC-vaccine that owned puissant aptitude to identify complicated TME as well as robust immunological activity to boost T-cell initiation, which may provide some insights into the design and application of DC-vaccines for clinical application.

BCG-Induced Tumor Immunity Requires Tumor-Intrinsic CIITA Independent of MHC-II.

For decades, BCG immunotherapy has been the standard of care for non-muscle-invasive bladder cancer. Despite this clinical experience, the mechanism by which BCG stimulates tumor-eliminating immunity is unclear, and there is still a need for more accurate prediction of clinical outcomes in advance of treatment initiation. We have shown that BCG stimulates tumor-specific T-cell immunity that requires tumor cell expression of the IFNγ receptor (IFNGR); however, the downstream components of IFNGR signaling responsible for responsiveness to BCG are unknown. Here, we demonstrate that the IFNγ-driven, tumor cell intrinsic expression of the class II transactivator CIITA is required for activation of a tumor-specific CD4 T-cell response and BCG-induced tumor immunity. Despite the established role for CIITA in controlling MHC-II antigen presentation machinery, the requirement for CIITA is independent of MHC-II and associated genes. Rather, we find that CIITA is required for a broader tumor-intrinsic transcriptional program linked to critical pathways of tumor immunity via mechanisms that remain to be determined. Tumor cell intrinsic expression of CIITA is not required for a response to immunotherapy targeting programmed cell death protein 1 (PD-1), suggesting that different modalities of immunotherapy for bladder cancer could be employed based on tumor-intrinsic characteristics.

IMMU-07. Interim analysis of the HIT-HGG Rez Immunvac study - Dendritic cell vaccination with partial Treg depletion and double checkpoint blockade in children with relapsed high-grade gliomas.

Relapses of high-grade gliomas show an aggressive course and survival 6 months after (sub-)total re-resection was only 62% in former HIT-HGG trials. Immunotherapy by induction of tumor-specific T cells through active immunization might help to control glioma regrowth. In the HIT-HGG-Rez Immunovac trial (Eudra-CT 2013-000419-26) we investigate whether a therapeutic vaccine (autologous dendritic cells loaded with tumor lysate, DCV) combined with Treg-depletion and double checkpoint-inhibition (CI, anti-PD-1/anti-CTLA4) is able to increase the number of patients alive 6 months after relapse. Here, we report interim results after 50% of the intended patients (n=25) have been recruited. 13 children and adolescents (mean age 12.7±4.0 y) with relapsed glioblastomas were screened for the trial so far. Three patients were screening failures, 10 patients received study treatment. Of these, 2 patients are currently vaccinated, so that 8 patients were evaluable for this interim analysis. 5 SAEs have been reported so far, none of them was limiting. 4 patients with gross total or subtotal resection at time of relapse had an overall survival (OS) of 13.2±4.0 months and a 6-month survival rate of 100%, which compares favourably to historical controls. 4 partially resected patients survived only 5.1±1.3 months and 6-months OS was 25%. Treg-depletion lead to a reduction of CD4+CD127-CD25+ T-cells of 45%, the majority of patients exhibited a tumor-specific T-cell response. We conclude that DCV in combination with partial Treg-depletion and CI is feasible, safe, and related with immunological responses. Double CI was not associated with unexpected toxicities. In (sub-)totally resected patients, immunotherapy seems to confer a survival advantage. For the completion of the trial we aim to include more patients with (sub-)totally resectable tumors to gain more insight into the nature and duration of the induced immune response. This trial is supported by Bristol Myers-Squibb (CA209-7JA).

Tumor-specific T cells support chemokine-driven spatial organization of intratumoral immune microaggregates needed for long survival

BackgroundThe composition of the tumor immune microenvironment (TIME) associated with good prognosis generally also predicts the success of immunotherapy, and both entail the presence of pre-existing tumor-specific T cells. Here,...

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.