To Tumor-associated Antigens Research Articles

Recent Advances in Nanomaterial-Based Immunotherapy for Prostate Cancer: A Comprehensive Review

Abstract: Prostate Cancer (PCa) remains a global health concern, and recent advancements in nanomaterial- based immunotherapy are reshaping the landscape of its treatment. The advent of Prostate- Specific Antigen (PSA) screening had a significant impact on the PCa burden until the early 21st century, but the ongoing innovations in therapeutic approaches and early detection methods have contributed to a decline in mortality rates. This comprehensive review delves into the evolving role of the immune system in cancer, with a particular emphasis on the latest advances in nanomaterial- based immunotherapy for PCa. The review focuses on the burgeoning field of nanomaterial- based immunotherapy for PCa, particularly in the context of vaccine-based therapies and immune checkpoint inhibitors. Recent developments in clinical trials highlight the effectiveness of immune checkpoint inhibitors, such as CTLA-4 and PD-1 inhibitors, either as standalone treatments or in combination for metastatic Castration-Resistant Prostate Cancer (mCRPC). We highlight ongoing clinical trials that explore PSMA-targeted CAR-T cells for mCRPC patients, offering valuable insights into the promising field of nanomaterial-based immunotherapy. The review also discusses nanomaterial-based vaccine treatments, such as Sipuleucel-T (Provenge®) and G-VAX. These work in different ways to boost the immune system's response to Tumor-Associated Antigens (TAAs). We also explore viral vector-based vaccines and gene therapy approaches, highlighting their potential to enhance the immune system's ability to target prostate cancer cells at the nanoscale. The article concludes with an in-depth discussion of the current and emerging nanomaterial-based biomarkers for PCa diagnosis and prognosis.

Results from a first-in-human phase I safety trial to evaluate the use of a vascularized pericranial/temporoparietal fascial flap to line the resection cavity following resection of newly diagnosed glioblastoma

PurposeThe efficacy of systemic therapies for glioblastoma (GBM) remains limited due to the constraints of systemic toxicity and blood–brain barrier (BBB) permeability. Temporoparietal fascial flaps (TPFFs) and vascularized peri cranial flaps (PCF) are not restricted by the blood–brain barrier (BBB), as they derive their vascular supply from branches of the external carotid artery. Transposition of a vascularized TPFF or PCF along a GBM resection cavity may bring autologous tissue not restricted by the BBB in close vicinity to the tumor bed microenvironment, permit ingrowth of vascular channels fed by the external circulation, and offer a mechanism of bypassing the BBB. In addition, circulating immune cells in the vascularized flap may have better access to tumor-associated antigens (TAA) within the tumor microenvironment. We conducted a first-in-human Phase I trial assessing the safety of lining the resection cavity with autologous TPFF/PCF of newly diagnosed patients with GBM.Methods12 patients underwent safe, maximal surgical resection of newly diagnosed GBMs, followed by lining of the resection cavity with a pedicled, autologous TPFF or PCF. Safety was assessed by monitoring adverse events. Secondary analysis of efficacy was examined as the proportion of patients experiencing progression-free disease (PFS) as indicated by response assessment in neuro-oncology (RANO) criteria and overall survival (OS). The study was powered to determine whether a Phase II study was warranted based on these early results. For this analysis, subjects who were alive and had not progressed as of the date of the last follow-up were considered censored and all living patients who were alive as of the date of last follow-up were considered censored for overall survival. For simplicity, we assumed that a 70% PFS rate at 6 months would be considered an encouraging response and would make an argument for further investigation of the procedure.ResultsMedian age of included patients was 57 years (range 46–69 years). All patients were Isocitrate dehydrogenase (IDH) wildtype. Average tumor volume was 56.6 cm3 (range 14–145 cm3). Resection was qualified as gross total resection (GTR) of all of the enhancing diseases in all patients. Grade III or above adverse events were encountered in 3 patients. No Grade IV or V serious adverse events occurred in the immediate post-operative period including seizure, infection, stroke, or tumor growing along the flap. Disease progression at the site of the original tumor was identified in only 4 (33%) patients (median 23 months, range 8–25 months), 3 of whom underwent re-operation. Histopathological analyses of those implanted flaps and tumor bed biopsy at repeat surgery demonstrated robust immune infiltrates within the transplanted flap. Importantly, no patient demonstrated evidence of tumor infiltration into the implanted flap. At the time of this manuscript preparation, only 4/12 (33%) of patients have died. Based on the statistical considerations above and including all 12 patients 10/12 (83.3%) had 6-month PFS. The median PFS was 9.10 months, and the OS was 17.6 months. 4/12 (33%) of patients have been alive for more than two years and our longest surviving patient currently is alive at 60 months.ConclusionsThis pilot study suggests that insertion of pedicled autologous TPFF/PCF along a GBM resection cavity is safe and feasible. Based on the encouraging response rate in 6-month PFS and OS, larger phase II studies are warranted to assess and reproduce safety, feasibility, and efficacy.Trial registration number and date of registration for prospectively registered trialsClinicalTrials.gov ID NCT03630289, dated: 08/02/2018.

Cross-reactive CD8+ T cell responses to tumor-associated antigens (TAAs) and homologous microbiota-derived antigens (MoAs)

BackgroundWe have recently shown extensive sequence and conformational homology between tumor-associated antigens (TAAs) and antigens derived from microorganisms (MoAs). The present study aimed to assess the breadth of T-cell recognition specific to MoAs and the corresponding TAAs in healthy subjects (HS) and patients with cancer (CP).MethodA library of > 100 peptide-MHC (pMHC) combinations was used to generate DNA-barcode labelled multimers. Homologous peptides were selected from the Cancer Antigenic Peptide Database, as well as Bacteroidetes/Firmicutes-derived peptides. They were incubated with CD8 + T cells from the peripheral blood of HLA-A*02:01 healthy individuals (n = 10) and cancer patients (n = 16). T cell recognition was identified using tetramer-staining analysis. Cytotoxicity assay was performed using as target cells TAP-deficient T2 cells loaded with MoA or the paired TuA.ResultsA total of 66 unique pMHC recognized by CD8+ T cells across all groups were identified. Of these, 21 epitopes from microbiota were identified as novel immunological targets. Reactivity against selected TAAs was observed for both HS and CP. pMHC tetramer staining confirmed CD8+ T cell populations cross-reacting with CTA SSX2 and paired microbiota epitopes. Moreover, PBMCs activated with the MoA where shown to release IFNγ as well as to exert cytotoxic activity against cells presenting the paired TuA.ConclusionsSeveral predicted microbiota-derived MoAs are recognized by T cells in HS and CP. Reactivity against TAAs was observed also in HS, primed by the homologous bacterial antigens. CD8+ T cells cross-reacting with MAGE-A1 and paired microbiota epitopes were identified in three subjects. Therefore, the microbiota can elicit an extensive repertoire of natural memory T cells to TAAs, possibly able to control tumor growth (“natural anti-cancer vaccination”). In addition, non-self MoAs can be included in preventive/therapeutic off-the-shelf cancer vaccines with more potent anti-tumor efficacy than those based on TAAs.

A Luminex Approach to Develop an Anti-Tumor-Associated Antigen Autoantibody Panel for the Detection of Prostate Cancer in Racially/Ethnically Diverse Populations.

(1) Background: Autoantibodies to tumor-associated antigens (TAAs) have emerged as promising cancer biomarkers. Luminex technology offers a powerful approach for the simultaneous detection of multiple anti-TAA autoantibodies. (2) Methods: We aimed to utilize Luminex technology to evaluate and optimize a panel of anti-TAAs autoantibodies for detecting prostate cancer (PCa), which included autoantibodies to fourteen TAAs. A total of 163 serum samples (91 PCa, 72 normal controls) were screened to determine the levels of the autoantibodies using the Luminex assay. (3) Results: Twelve autoantibodies exhibited significantly high frequencies ranging from 19.8% to 51.6% in the PCa group. Receiver operating characteristic (ROC) curve analysis revealed area under the curve (AUC) values ranging from 0.609 to 0.868 for the twelve autoantibodies individually. We further confirmed the performance of the HSP60 autoantibody by using an enzyme-linked immunosorbent assay (ELISA) in a larger sample comprising 200 PCa sera, 20 benign prostatic hyperplasia (BPH) sera, and 137 normal control sera. The results obtained from the Luminex assay were consistent with the ELISA findings. We developed a panel consisting of three autoantibodies (p16, IMP2, and HSP60) which achieved an impressive AUC of 0.910 with a sensitivity of 71.4% and a specificity of 95.8%. The panel was also evaluated in PCa patients from different races/ethnicities with the best performance observed in distinguishing the Hispanic American patients with PCa from normal controls. (4) Conclusions: We developed an anti-TAA autoantibody panel for the detection of PCa that exhibits promising performance. This panel holds significant potential as a high-throughput tool to facilitate PCa detection.

Abstract 5747: A novel combination therapy of arenavirus vectors and PD1-IL2v strongly potentiates tumor specific T cell responses resulting in synergistic anti-tumor efficacy

Abstract It is undisputed that CD8 T cells play a critical role in controlling tumor growth and killing tumor cells, and that tumor specific T cells are essential for clinical responses to immune checkpoint inhibitors. Yet, the induction and maintenance of functional tumor antigen specific T cell responses represent still one of the greatest challenges in cancer immunotherapy. Therapeutic cancer vaccines based on engineered arenavirus vectors have been shown preclinically to overcome self-tolerance to tumor associated antigens (TAA) and mount unprecedented T cell responses, both, in preclinical tumor models as well as HPV16+ cancer patients in an ongoing Phase 1/2 trial. The novel PD-1 targeted IL-2 variant (PD1-IL2v) was created to maximize the potency of IL-2R activation of effector T cells while overcoming the toxicities of wildtype IL-2. Cis binding of PD1-IL2v to PD-1 and IL-2Rβγ on the same cell was recently shown to promote differentiation of stem-like CD8 T cells into better effectors and was therefore identified as an ideal compound for combination therapies with arenavirus vectors. Combination of vectors encoding tumor associated foreign or self-antigens with PD1-IL2v lead to a massive, up to 60-fold, increase of peripheral tumor specific CD8 T cell numbers compared to vector treatment alone. Notably, frequency of peripheral regulatory T cells was not enhanced by this combination. The massive increase of TAA specific CD8 T cells was associated with synergistic anti-tumor efficacy in two independent tumor models, resulting in longer survival times and up to 60% complete responders. Complete tumor clearance resulted in a stable memory T cell population and protection against tumor re-challenge. Ongoing studies will address modifications of the tumor microenvironment and further characterization of tumor infiltrating T cells upon combination therapy. These preclinical data establish the combination of arenavirus vectors and PD1-IL2v as a promising next generation cancer immunotherapy. Citation Format: Judith Strauss, Diana Reckendorfer, Kimberly Pojar, Laura Codarri Deak, Valeria Nicolini, Roger Sutmuller, Christian Klein, Pablo Umaña, Klaus K. Orlinger, Henning Lauterbach. A novel combination therapy of arenavirus vectors and PD1-IL2v strongly potentiates tumor specific T cell responses resulting in synergistic anti-tumor efficacy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5747.

Abstract 3328: Using Luminex approach to develop a panel of anti-TAA autoantibodies for the detection of prostate cancer

Abstract Autoantibodies to tumor-associated antigens (TAAs) have been demonstrated as reporters in early carcinogenesis. Luminex technology enables the development of simultaneous detection of multiple autoantibodies. This study aimed to use Luminex technology to evaluate and develop an optimal panel for the detection of prostate cancer (PCa) based on autoantibodies to fourteen TAAs (p53, p16, IMP2, IMP3, SOX2, BIRC5, HIF1-α, HSP60, ENO1, CTAG1B, MUC1, Her2, GAL1, and GAL3) associated with cancers. A total of 163 samples including 91 PCa sera and 72 normal control sera were screened to evaluate the expression of fourteen autoantibodies by multiple autoantibody bead panel. Except for autoantibodies to Her2 and IMP3, twelve autoantibodies showed significantly high frequencies ranging from 19.8% to 51.6% in the PCa group at 95.8% specificity for normal controls. The area under the curve (AUC) of these twelve autoantibodies ranged from 0.609 to 0.868. After logistic regression modeling and leave-one-out cross-validation, an optimal panel with the combination of three autoantibodies to p16, IMP2, and HSP60 was developed, achieving an AUC of 0.909 with 71.4% sensitivity and 95.8% specificity. Autoantibody to HSP60 exhibiting the best performance with an AUC of 0.868 in the autoantibody bead panel was further validated by Enzyme-linked immunosorbent assay (ELISA) with a larger size sample containing 200 PCa sera and 137 normal control sera, it also showed an AUC of 0.848 to identify PCa from normal controls. Therefore, the autoantibody bead panel showed similar results to ELISA. In summary, we developed an optimal autoantibody bead-based panel for the detection of PCa. It could be used as a high throughput tool to facilitate Pca detection. Citation Format: Cuipeng Qiu, Xiao Wang, Serina Batson, Giulio Francia, Jian-Ying Zhang. Using Luminex approach to develop a panel of anti-TAA autoantibodies for the detection of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3328.

Autoantibodies to PAX5, PTCH1, and GNA11 as Serological Biomarkers in the Detection of Hepatocellular Carcinoma in Hispanic Americans

Studies have demonstrated that autoantibodies to tumor-associated antigens (TAAs) may be used as efficient biomarkers with low-cost and highly sensitive characteristics. In this study, an enzyme-linked immunosorbent assay (ELISA) was conducted to analyze autoantibodies to paired box protein Pax-5 (PAX5), protein patched homolog 1 (PTCH1), and guanine nucleotide-binding protein subunit alpha-11 (GNA11) in sera from Hispanic Americans including hepatocellular carcinoma (HCC) patients, patients with liver cirrhosis (LC), patients with chronic hepatitis (CH), as well as normal controls. Meanwhile, 33 serial sera from eight HCC patients before and after diagnosis were used to explore the potential of these three autoantibodies as early biomarkers. In addition, an independent non-Hispanic cohort was used to evaluate the specificity of these three autoantibodies. In the Hispanic cohort, at the 95.0% specificity for healthy controls, 52.0%, 44.0%, and 44.0% of HCC patients showed significantly elevated levels of autoantibodies to PAX5, PTCH1, and GNA11, respectively. Among patients with LC, the frequencies for autoantibodies to PAX5, PTCH1, and GNA11 were 32.1%, 35.7%, and 25.0%, respectively. The area under the ROC curves (AUCs) of autoantibodies to PAX5, PTCH1, and GNA11 for identifying HCC from healthy controls were 0.908, 0.924, and 0.913, respectively. When these three autoantibodies were combined as a panel, the sensitivity could be improved to 68%. The prevalence of PAX5, PTCH1, and GNA11 autoantibodies has already occurred in 62.5%, 62.5%, or 75.0% of patients before clinical diagnosis, respectively. In the non-Hispanic cohort, autoantibodies to PTCH1 showed no significant difference; however, autoantibodies to PAX5, PTCH1, and GNA11 showed potential value as biomarkers for early detection of HCC in the Hispanic population and they may monitor the transition of patients with high-risk (LC, CH) to HCC. Using a panel of the three anti-TAA autoantibodies may enhance the detection of HCC.

Awaken Immune Cells by Hapten Enhanced Intratumoral Chemotherapy with Penicillin Prolong Pancreatic Cancer Survival.

Intratumoral immunotherapy is well studied and is ongoing, but few studies have evaluated the relationship between of cytotoxic drugs intratumoral injection (CDI) and hapten-enhanced cytotoxic drugs intratumoral injection (HECDI) and patient survival. The objectives of this study include comparisons to explore possible associations between the proportions of treatment-induced cytokines and autologous antibodies to tumor-associated antigens (TAAs) and the relative size of the abscopal effects concurring. CDIs contain oxidant and cytotoxic drugs, HECDIs contains the same drug plus penicillin as the new Hapten. Of the 33 patients with advanced pancreatic cancer, 9 received CDI, 20 received HECDI, and 4 (control group) received placebo. Serum levels of cytokines and autoantibodies of TAAs were detected and compared after therapy. The 1-year survival rate was 11.11% for CDI and 52.63% for HECDI (P= 0.035). In the general analysis of cytokines, HECDI exhibited an increasing level of IFN-γ and IL-4, and the non-hapten CDI showed a rising level of IL-12 (P = 0.125, 0.607, & 0.04). Participants who did not receive chemotherapy had significant differences in the level of Zeta autoantibody only before and after HECDI; However, IMP1 levels in patients with previous chemotherapy experience were significantly different before and after HECDI and CDI treatment (P≤0.05, P = 0.316). After HECDI treatment, TAA autoantibodies of RalA, Zeta, HCC1, p16 increased (P = 0.429, 0.416, 0.042, 0.112). The elevated levels of CXCL8, IFN-γ, HCC1, RalA, Zeta, and p16 observed in HECDI may be attributed to the abscopal effect (P = 0.012 & 0.013). Overall survival rates indicated that HECDI treatment extended participants' lives.

A bispecific, crosslinking lectibody activates cytotoxic T cells and induces cancer cell death.

Aberrant glycosylation patterns play a crucial role in the development of cancer cells as they promote tumor growth and aggressiveness. Lectins recognize carbohydrate antigens attached to proteins and lipids on cell surfaces and represent potential tools for application in cancer diagnostics and therapy. Among the emerging cancer therapies, immunotherapy has become a promising treatment modality for various hematological and solid malignancies. Here we present an approach to redirect the immune system into fighting cancer by targeting altered glycans at the surface of malignant cells. We developed a so-called "lectibody", a bispecific construct composed of a lectin linked to an antibody fragment. This lectibody is inspired by bispecific T cell engager (BiTEs) antibodies that recruit cytotoxic T lymphocytes (CTLs) while simultaneously binding to tumor-associated antigens (TAAs) on cancer cells. The tumor-related glycosphingolipid globotriaosylceramide (Gb3) represents the target of this proof-of-concept study. It is recognized with high selectivity by the B-subunit of the pathogen-derived Shiga toxin, presenting opportunities for clinical development. The lectibody was realized by conjugating an anti-CD3 single-chain antibody fragment to the B-subunit of Shiga toxin to target Gb3+ cancer cells. The reactive non-canonical amino acid azidolysine (AzK) was inserted at predefined single positions in both proteins. The azido groups were functionalized by bioorthogonal conjugation with individual linkers that facilitated selective coupling via an alternative bioorthogonal click chemistry reaction. In vitro cell-based assays were conducted to evaluate the antitumoral activity of the lectibody. CTLs, Burkitt´s lymphoma-derived cells and colorectal adenocarcinoma cell lines were screened in flow cytometry and cytotoxicity assays for activation and lysis, respectively. This proof-of-concept study demonstrates that the lectibody activates T cells for their cytotoxic signaling, redirecting CTLs´ cytotoxicity in a highly selective manner and resulting in nearly complete tumor cell lysis-up to 93%-of Gb3+ tumor cells in vitro. This research highlights the potential of lectins in targeting certain tumors, with an opportunity for new cancer treatments. When considering a combinatorial strategy, lectin-based platforms of this type offer the possibility to target glycan epitopes on tumor cells and boost the efficacy of current therapies, providing an additional strategy for tumor eradication and improving patient outcomes.

The mechanisms on evasion of anti-tumor immune responses in gastric cancer.

The immune system and the tumor have been at each other's throats for so long that the neoplasm has learned to avoid detection and avoid being attacked, which is called immune evasion. Malignant tumors, such as gastric cancer (GC), share the ability to evade the body's immune system as a defining feature. Immune evasion includes alterations to tumor-associated antigens (TAAs), antigen presentation mechanisms (APMs), and the tumor microenvironment (TME). While TAA and APM are simpler in nature, they both involve mutations or epigenetic regulation of genes. The TME is comprised of numerous cell types, cytokines, chemokines and extracellular matrix, any one of which might be altered to have an effect on the surrounding ecosystem. The NF-kB, MAPK, PI3K/AKT, JAK/STAT, Wnt/β-catenin, Notch, Hippo and TGF-β/Smad signaling pathways are all associated with gastric cancer tumor immune evasion. In this review, we will delineate the functions of these pathways in immune evasion.

Abstract 5149: Autoantibodies to PAX5, PTCH1 and GNA11 as serological biomarkers in the detection of hepatocellular carcinoma in Hispanic Americans

Abstract Liver cancer, especially hepatocellular carcinoma (HCC), is the third cause of cancer death worldwide. In the United States, it remains higher incidence rates and worse survival in the Hispanic population than the other populations. Studies have demonstrated that autoantibodies to tumor-associated antigens (TAAs) could be biomarkers with low-cost, efficient, and highly sensitive characteristics. In this study, enzyme-linked immunosorbent assay (ELISA) was conducted to measure three autoantibodies to PAX5, PTCH1, and GNA11 in sera from 25 Hispanic Americans with HCC, 28 patients with liver cirrhosis (LC), and 27 patients with chronic hepatitis (CH) as well as sera from 85 healthy individuals. At the 95% specificity for healthy controls, 56%, 48%, and 44% of HCC sera (or patients) showed elevated levels of autoantibodies to PAX5, PTCH1, and GNA11 respectively. Among the patients with LC, frequencies for autoantibodies to PAX5, PTCH1, and GNA11 were 44%, 36%, and 25% respectively. In patients with CH, the frequencies of autoantibodies to PAX5, PTCH1, and GNA11 were 22%, 22%, and 15%, which were significantly lower than those in HCC (p<0.01). The area under the curves (AUCs) of autoantibodies to PAX5, PTCH1, and GNA11 for identifying HCC from healthy controls were 0.912, 0.915, and 0.915, respectively. The sensitivity could be improved to 68% when three of the autoantibodies were combined with the AUC of 0.932. Therefore, autoantibodies to PAX5, PTCH1, and GNA11 showed significantly higher levels in Hispanic HCC than those in the CH or healthy controls. Also, these three autoantibodies could enhance the detection of HCC if they were combined as the parallel test. In conclusion, autoantibodies to PAX5, PTCH1, and GNA11 could be potential biomarkers for the detection of HCC in Hispanic Americans. Large size of samples is needed to further determine their potential value in clinical application. Citation Format: Cuipeng Qiu, Xiao Wang, Bofei Wang, Yangcheng Ma, Xiaojun Zhang, Jian-Ying Zhang. Autoantibodies to PAX5, PTCH1 and GNA11 as serological biomarkers in the detection of hepatocellular carcinoma in Hispanic Americans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5149.

Abstract 5616: Tumor-targeted immune activation via a site-specific TLR7-agonist antibody-drug conjugate

Abstract Traditional antibody-drug conjugates (ADCs) selectively deliver cytotoxic payloads to tumor-associated antigen (TAA)-expressing tumor cells, thereby limiting healthy cell damage and toxicities associated with systemic administration. Analogously, a novel class of immune-stimulating antibody conjugates (ISACs) has recently emerged to achieve tumor-targeted activation of anti-tumor immune responses, avoiding dose-limiting immunotoxicities seen with the systemic immune agonist delivery. Most of the ADC or ISAC to date utilize random payload conjugation to native surface-exposed lysines or cysteines, and relatively labile linkage chemistries, leading to conjugation site and drug-to-antibody ratio (DAR) heterogeneity, and ADC/ISAC instability in systemic circulation. In particular, the presence of high-DAR species and linker instability can lead to off-tumor toxicity, thus limiting the therapeutic window. Here we describe the generation and preclinical characterization of a site-specific TLR7-agonist (TLR7a) ISAC targeting an undisclosed TAA1. To specify the conjugation site and DAR, a non-natural amino acid (nnAA), para-acetyl-L-phenylalanine (pAF) was genetically incorporated at defined sites within the anti-TAA1 antibody, providing an orthogonal chemical handle for covalent TLR7 agonist payload conjugation through a highly stable oxime bond. Using this site-specific, homogenous ISAC platform, we systematically screened different conjugate sites and TLR7 agonist payloads to obtain an optimized TAA1-TLR7a ISAC drug candidate. ISAC platform stability, homogeneity, and flexibility were critical, because conjugation site and payload structure dramatically influenced ISAC in vitro activity, PK profile and in vivo efficacy. Using in vitro co-culture assays with human immune cells and tumor cell lines, we showed that the optimized TAA1 ISAC can induce multiple anti-tumor immune mechanisms, including proinflammatory cytokine production, the myeloid cell activation markers induction and enhanced ADCC mediated tumor cell killing. The TAA1 ISAC is 100-fold more active than the free, unconjugated TLR7 agonist, and all activity is conditional on the presence of TAA1-expressing tumor cells. Finally, we demonstrated in vivo efficacy in both xenograft and syngeneic tumor models. In a syngeneic MC38-tumor model expressing human TAA1, ISAC treatment led to complete tumor regression and formation of immunologic memory. These results provide a strong rationale for site-specific TLR7 agonist ISAC as a next generation platform for tumor-targeted, innate immune agonist immunotherapy. Citation Format: Mingchao Kang, Sung-Ju Moon, Ji Young Kim, Andy Beck, Molly Allen, Jay Nelson, Keith Tatsukawa, Hon Tran, Manoj Pal, Michael Gray, Nick Knudsen, Lillian Skidmore, David Mills, Yingchun Lu, Ying Buechler, Sukumar Sakamuri, Shawn Zhang, Feng Tian. Tumor-targeted immune activation via a site-specific TLR7-agonist antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5616.

Abstract 1860: Bispecific claudin-6 x CD3 antibodies in a 2 + 1 format demonstrate selectivity and activity on human ovarian cancer cells

Abstract There is a large unmet need for targeted therapies to treat ovarian cancer and other solid tumors. A promising strategy is the use of T cell engaging bispecific antibodies that recruit T cells to kill cancer cells by simultaneously binding to tumor-associated antigens (TAA) on cancer cells and CD3 on T cells. Effective and safe use of these therapeutics depends on selective targeting of cancer cells over normal tissue, feasible when a TAA is more highly expressed on cancer cells versus normal tissues. Selectivity can also be improved by using a mixed valency “2 + 1” bispecific format, coupled with target affinity tuning, to achieve avid binding to the TAA. Claudin-6 (CLDN6) is a tetraspan membrane protein, a member of the claudin family of tight junction proteins, and has been identified as a promising TAA for ovarian cancer due to its high expression on ovarian and other cancer tissues and low expression on normal tissue. However, a complicating factor is that many proteins in the claudin family have high sequence identity. Most similar to CLDN6 is CLDN9, and the two proteins differ at only 3/76 residues in their extracellular loops, creating a challenge for the development of highly selective CLDN6 antibodies. We analyzed CLDN6 and CLDN9 expression using a combination of normal tissue gene expression data (GTEx), cancer cell genomics data (TCGA), and immunohistochemistry (IHC) on a panel of cancer and normal tissues. Data confirmed the tumor-specific expression pattern of CLDN6 but indicated high CLDN9 expression in normal tissues, suggesting that strong antibody selectivity for CLDN6 versus CLDN9 is critical. We created CLDN6-selective T cell engaging bispecific antibodies by starting with a highly selective monoclonal antibody humanized from a mouse hybridoma. Selectivity was further improved by engineering the CDR regions. Variant antibodies were screened for binding to transiently transfected HEK293E cells that highly expressed either CLDN6, CLDN9, or other homologous claudin family members. Selective variants were converted into the XmAb® 2 + 1 bispecific antibody format and tested in T cell-dependent cellular cytotoxicity (TDCC) assays using cancer cell lines expressing CLDN6, or HEK293E cells transfected with claudin homologs. A set of lead CLDN6 x CD3 bispecifics displaying a range of potencies on CLDN6+ cancer cell lines and high selectivity for CLDN6 over CLDN9 and other homologous claudins was identified. Tolerability and pharmacokinetics of these molecules are currently being assessed in non-human primates, and activity will be evaluated in humanized mouse models of ovarian cancer. Citation Format: Matthew S. Faber, Sung-Hyung Lee, Yoon Kyung Kim, Jing Qi, Kendra N. Avery, Duc-Hanh T. Nguyen, Rumana Rashid, Araz Eivazi, Seung Y. Chu, Juan E. Diaz, Connie Ardila, Ruschelle Love, Alex Nisthal, Norman J. Barlow, Christine Bonzon, Umesh S. Muchhal, Matthew J. Bernett, John R. Desjarlais. Bispecific claudin-6 x CD3 antibodies in a 2 + 1 format demonstrate selectivity and activity on human ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1860.

Autoantibodies to tumor-associated antigens in lung cancer diagnosis.

Lung cancer (LC) accounts for the majority of cancer-related deaths worldwide. Although screening the high-risk population by low-dose CT (LDCT) has reduced mortality, the cost and high false positivity rate has prevented its general diagnostic use. As such, better and more specific minimally invasive biomarkers are needed in general and for early LC detection, specifically. Autoantibodies produced by humoral immune response to tumor-associated antigens (TAA) are emerging as a promising noninvasive biomarker for LC. Given the low sensitivity of any one single autoantibody, a panel approach could provide a more robust and promising strategy to detect early stage LC. In this review, we summarize the background of TAA autoantibodies (TAAb) and the techniques currently used for identifying TAA, as well as recent findings of LC specific antigens and TAAb. This review provides guidance toward the development of accurate and reliable TAAb as immunodiagnostic biomarkers in the early detection of LC.

Integrating CD4+ T cell help for therapeutic cancer vaccination in a preclinical head and neck cancer model

ABSTRACT Head and neck squamous cell carcinomas (HNSCC) are well suited for cancer vaccination strategies. In addition to tumor-associated antigens (TAAs) and endogenous retrovirus (ERV) encoded proteins, HNSCCs have a relatively high tumor mutational burden encoding potential neoepitopes. Peptide vaccine candidates are prioritized by predicted high-affinity to major histocompatibility complex (MHC) class I with MHC-II affinity largely not being considered. Herein, we extend previous studies to evaluate therapeutic vaccination in the mouse oral cancer (MOC) 22 model. Two distinct MOC22 derived SLPs were tested – a TSA-oriented mutant intercellular adhesion molecule 1 (mICAM1) and p15E, an ERV encoded antigen. In silico prediction revealed mICAM1 SLP bore strong MHC-I and MHC-II epitopes sharing a mutant residue with vaccination significantly increasing both antigen-specific IFN-γ producing CD4+ and CD8+ T cells. By contrast, p15E SLP had a predicted high-affinity MHC-I epitope but lacked an MHC-II epitope and vaccination induced antigen-specific CD8+ but not CD4+ T cell responses. Therapeutic mICAM1 vaccination attenuated tumor growth effectively with mICAM1-specific T cells displaying durable IFN-γ production compared with p15E SLP. Furthermore, mICAM1 SLPs carrying weakened MHC-II binding epitopes were unable to control tumor growth. These data underscore the potential value of therapeutic targeting of HNSCC epitopes and highlight the importance of studying distinct antigen classes in this setting. Moreover, they raise the possibility that, at least in part, CD4+ T cell help is critical for cancer vaccination in this preclinical HNSCC model and suggest in silico prediction approaches prioritize overlapping MHC-I and MHC-II epitopes to generate potent cancer vaccines.

Using protein microarray to identify and evaluate autoantibodies to tumor-associated antigens in ovarian cancer.

The aim of this study was to develop a noninvasive serological diagnostic approach in identifying and evaluating a panel of candidate autoantibodies to tumor‐associated antigens (TAAs) based on protein microarray technology for early detection of ovarian cancer (OC). Protein microarray based on 154 proteins encoded by 138 cancer driver genes was used to screen candidate anti‐TAA autoantibodies in a discovery cohort containing 17 OC and 27 normal controls (NC). Indirect enzyme‐linked immunosorbent assay (ELISA) was used to detect the content of candidate anti‐TAA autoantibodies in sera from 140 subjects in the training cohort. Differential anti‐TAA autoantibodies were further validated in the validation cohort with 328 subjects. Subsequently, 112 sera from the patients with ovarian benign diseases with 104 OC sera and 104 NC sera together were recruited to identify the specificity of representative autoantibodies to OC among ovarian diseases. Five TAAs (GNAS, NPM1, FUBP1, p53, and KRAS) were screened out in the discovery phase, in which four of them presented higher levels in OC than controls (P < .05) in the training cohort, which was consistent with the result in the subsequent validation cohort. An optimized panel of three anti‐TAA (GNAS, p53, and NPM1) autoantibodies was identified to have relatively high sensitivity (51.2%), specificity (86.0%), and accuracy (68.6%), respectively. This panel can identify 51% of OC patients with CA125 negative. This study supports our assumption that anti‐TAA autoantibodies can be considered as potential diagnostic biomarkers for detection of OC; especially a panel of three anti‐TAA autoantibodies could be a good tool in immunodiagnosis of OC.

Circulating Interleukin-4 Is Associated with a Systemic T Cell Response against Tumor-Associated Antigens in Treatment-Naïve Patients with Resectable Non-Small-Cell Lung Cancer.

Simple SummaryCytokines can increase the activity of T cells specific for tumor-associated antigens and thereby promote tumor-specific immune responses. In this study, cytokine profiles and T cell responses against 14 tumor-associated antigens were investigated in 36 treatment-naïve patients with resectable non-small cell lung cancer. Based on these results, preoperative serum interleukin-4 levels can play a role in predicting T cell responses specific for tumor-associated antigens and recurrence-free survival regardless of tumor stage. This is clinically relevant as patients with high preoperative serum interleukin-4 levels could be at high risk of postoperative tumor recurrence and, therefore, should be considered for adjuvant or neoadjuvant treatment. From this perspective, preoperative serum interleukin-4 levels may become a useful option to assess the risk of postoperative tumor recurrence in non-small-cell lung cancer.Spontaneous T cell responses to tumor-associated antigens (TAs) in the peripheral blood of patients with non-small-cell lung cancer (NSCLC) may be relevant for postoperative survival. However, the conditions underlying these T cell responses remain unclear. We quantified the levels of 27 cytokines in the peripheral blood and tumor tissues from treatment-naïve patients with NSCLC (n = 36) and analyzed associations between local and systemic cytokine profiles and both TA-specific T cell responses and clinical parameters. We defined T cell responders as patients with circulating T cells that were reactive to TAs and T cell nonresponders as patients without detectable TA-specific T cells. TA-specific T cell responses were correlated with serum cytokine levels, particularly the levels of interleukin(IL)-4 and granulocyte colony-stimulating factor (G-CSF), but poorly correlated with the cytokine levels in tumor tissues. Nonresponders showed significantly higher serum IL-4 levels than responders (p = 0.03); the predicted probability of being a responder was higher for individuals with low serum IL-4 levels. In multivariable Cox regression analyses, in addition to IL-4 (hazard ratio (HR) 2.8 (95% confidence interval (CI): 0.78–9.9); p = 0.116), the age-adjusted IL-8 level (HR 3.9 (95% CI: 1.05–14.5); p = 0.042) predicted tumor recurrence. However, this study included data for many cytokines without adjustment for multiple testing; thus, the observed differences in IL-4 or IL-8 levels might be incidental findings. Therefore, additional studies are necessary to confirm these results.

In pancreatic cancer, chemotherapy increases antitumor responses to tumor-associated antigens and potentiates DNA vaccination

BackgroundPancreatic ductal adenocarcinoma (PDA) is an almost incurable tumor that is mostly resistant to chemotherapy (CT). Adaptive immune responses to tumor-associated antigens (TAA) have been reported, but immunotherapy (IT) clinical...

Serological Biomarkers for Early Detection of Hepatocellular Carcinoma: A Focus on Autoantibodies against Tumor-Associated Antigens Encoded by Cancer Driver Genes.

Substantial evidence manifests the occurrence of autoantibodies to tumor-associated antigens (TAAs) in the early stage of hepatocellular carcinoma (HCC), and previous studies have mainly focused on known TAAs. In the present study, protein microarrays based on cancer driver genes were customized to screen TAAs. Subsequently, autoantibodies against selected TAAs in sera were tested by enzyme-linked immunosorbent assays (ELISA) in 1175 subjects of three independent datasets (verification dataset, training dataset, and validation dataset). The verification dataset was used to verify the results from the microarrays. A logistic regression model was constructed within the training dataset; seven TAAs were included in the model and yielded an area under the receiver operating characteristic curve (AUC) of 0.831. The validation dataset further evaluated the model, exhibiting an AUC of 0.789. Remarkably, as the aggravation of HCC increased, the prediction probability (PP) of the model tended to decrease, the trend of which was contrary to alpha-fetoprotein (AFP). For AFP-negative HCC patients, the positive rate of this model reached 67.3% in the training dataset and 50.9% in the validation dataset. Screening TAAs with protein microarrays based on cancer driver genes is the latest, fast, and effective method for finding indicators of HCC. The identified anti-TAA autoantibodies can be potential biomarkers in the early detection of HCC.

Neoadjuvant PROSTVAC prior to radical prostatectomy enhances T-cell infiltration into the tumor immune microenvironment in men with prostate cancer

BackgroundClinical trials have shown the ability of therapeutic vaccines to generate immune responses to tumor-associated antigens (TAAs). What is relatively less known is if this translates into immune-cell (IC) infiltration...