Tumor Cell Surface Antigens Research Articles

Abstract PO2-03-07: Immune Landscape in PD-L1-positive and TROP2-positive Triple-Negative Breast Cancer

Abstract Background: Triple-negative breast cancer (TNBC) tends to be more aggressive, and more likely to recur than other subtypes of breast cancer, and patients with metastatic TNBC have a poor prognosis. The recent approvals and data of pembrolizumab (anti-PD-1 inhibitor) in combination with chemotherapy in advanced-metastatic and early high-risk TNBC, and sacituzumab govitecan (an ADC that targets the tumor cell surface antigen TROP2 coupled with the irinotecan metabolite SN-38) in metastatic TNBC, has shed light on some of the immune and cancer signaling associated with TNBC. Although exciting progress has been made in the treatment of TNBC, there are still important gaps to fill to understand the biology of TNBC and identify additional therapies. Materials and Methods: We identified a total of 1500 patients whose tumors were negative for the expression of ER and HER2 receptors by gene array. PD-L1 and TROP2 expression data were available for 802 early TNBC patients, of whom 657 were treated with adjuvant chemotherapy. A comprehensive identification and analysis of immune-related genes (n= 1169) was conducted. Mann-Whitney test comparing the gene expression for all immune related-genes was evaluated in patients expressing PD-L1 and TROP2 at low and high expression levels. Immune gene modules resembling key immune gene signaling were analyzed in all subgroups identified. Fold changes and Mann-Whitney P values were calculated in each subgroup. Results: Patients were stratified based on high and low expression levels of PD-L1 and TROP-2 mRNA. PD-L1 highly expressing (PD-L1+) tumors showed a marked difference in immune-related genes as compared to PD-L1 low-level tumors (PD-L1-) with PD-L1+ tumors demonstrating a significantly higher proportion of correlated immune genes (CXCL9/10/11, IFN-γ, CCL5 and STAT1). TROP2 highly and low expressing tumors (TROP2+ and TROP2-, respectively) showed a relatively limited difference in terms of immune-related gene expression with key immune-related genes having statistical differential expression in the two subgroups. TROP2+ tumors showed a high presence of several Mucin family gene members (MUC1, -5AC, -4). In addition, CLDN 4, VTCN1, and MET were among the key immune genes significantly expressed in TROP2+ tumors (P = 5.73E-20; P = 6.2E-13, P = 2.1E-11). Overall, PD-L1+ tumors and TROP2+ tumors showed an immune suppressive genomic landscape but were potentially regulated by different signaling. Of note, tumors with very high expression of PD-L1 showed an inverse correlation with VTCN1 gene expression. Conclusions: This preliminary analysis confirmed that only a limited number of early TNBC highly expressed PD-L1 and that a different immune suppressive landscape for PD-L1± and TROP2± tumors exists. In addition, our data suggest that early TNBC cases lacking PD-L1 might escape immune surveillance by virtue of the upregulation of key alternate signaling. Ongoing efforts investigating the expression of such markers on stroma/epithelial tumor components will help to clarify their biological, clinical, and potential therapeutic role in TNBC. Citation Format: Balazs Gyorffy, Libero Santarpia. Immune Landscape in PD-L1-positive and TROP2-positive Triple-Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-03-07.

Antibody-Drug Conjugates in the Treatment of Genitourinary Cancers: An Updated Review of Data.

The treatment landscape of genitourinary cancers has significantly evolved over the past few years. Renal cell carcinoma, bladder cancer, and prostate cancer are the most common genitourinary malignancies. Recent advancements have produced new targeted therapies, particularly antibody-drug conjugates (ADCs), due to a better understanding of the underlying oncogenic factors and molecular mechanisms involved. ADCs function as a 'drug delivery into the tumor' system. They are composed of an antigen-directed antibody linked to a cytotoxic drug that releases cytotoxic components after binding to the tumor cell's surface antigen. ADCs have been proven to be extremely promising in the treatment of several cancer types. For GU cancers, this novel treatment has only benefited patients with metastatic urothelial cancer (mUC). The rest of the GU cancer paradigm does not have any FDA-approved ADC treatment options available yet. In this study, we have thoroughly completed a narrative review of the current literature and summarized preclinical studies and clinical trials that evaluated the utility, activity, and toxicity of ADCs in GU cancers, the prospects of ADC development, and the ongoing clinical trials. Prospective clinical trials, retrospective studies, case reports, and scoping reviews were included.

Abstract 8: Deep Immunomics pipeline for discovery and validation of novel cancer-specific T cell receptors

Abstract Background: T cell receptor-engineered T cell (TCR-T) therapy has been studied as a high potential approach for cancer treatment. Beyond cell-surface tumor antigens, TCR-Ts can recognize HLA-presented intracellular epitopes which allows them to address a wide range of cancer-specific targets. Existing TCR-T therapies focus on a limited number of epitopes, many of which are restricted to HLA allele HLA-A*02:01. Identification of novel anti-tumor TCRs covering a broad range of HLA alleles is necessary to address unmet clinical needs. Natural T cells undergo thymic selection and present a favorable safety profile for mining such anti-tumor TCRs for therapeutic development. However, discovery of natural anti-tumor TCRs has been challenging due to i) the absence of high-throughput methods for identifying tumor-reactive TCRs in limited quantity human samples and ii) lack of sensitivity in detecting low frequency, naturally occurring tumor-reactive T cells. Methods: We developed TargetScape® as a part of our Deep Immunomics platform for efficient discovery of natural tumor-specific TCRs in healthy donors and cancer patients. Cells from blood and tissue samples were stained with metal-barcoded peptide-MHC tetramers, containing 500+ tumor-specific antigens, alongside metal-conjugated antibodies, allowing rapid identification and high dimensional phenotypic analysis of CD8+ T cells at the millions of cells scale. Single-cell sequencing revealed paired TCR sequences. Selected TCRs were introduced into luminescent Jurkat reporter cells for validation screening with peptide-pulsed targets and the relevant HLA restriction. TCRs of interest were further integrated into primary T cells and evaluated for their effector function. Results: We utilize our sensitive, high-throughput TargetScape® platform to detect and characterize putative cancer-specific TCRs from blood and tissue samples in frequencies as low as ~0.003% of total CD8+ cells. We have functionally validated over 100 TargetScape® derived TCRs with luminescent Jurkat reporters. Validated TCRs cover high prevalence HLA alleles and target a broad range of cancer antigen classes, including tumor associated antigens (TAA), Human endogenous retroviruses (HERVs), shared splice variants, and frameshift mutations. Several natural TCRs demonstrate recognition of low concentrations of peptide, indicating high functional avidity. Further evaluations of specificity and activity of TCRs of interest transduced into primary T cells are currently in progress. Conclusions: Our Deep Immunomics platform allows us to identify and confirm activity of novel, naturally-derived TCR candidates against therapeutically relevant cancer antigens presented on six common HLA alleles. These findings validate our discovery workflow leading to a portfolio of potential clinically relevant candidates that are currently under preclinical development. Citation Format: Hannah Fields, Juliana Velez Lujan, Kan Xing Wu, Natalie Epstein, Nazihah Beevi, Florence Chioh, Nicholas Tan, Neeraja Kulkarni, Noella Mukobo, Srikanthi R, Yovita Purwanti, Evan Newell, Alessandra Nardin, Michael Fehlings, Katja Fink, Daniel MacLeod. Deep Immunomics pipeline for discovery and validation of novel cancer-specific T cell receptors [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 8.

Antibody-drug conjugates targeting HER2 for the treatment of urothelial carcinoma: potential therapies for HER2-positive urothelial carcinoma.

Urothelial carcinoma (UC) is a common cancer characterized by high morbidity and mortality rates. Despite advancements in treatment, challenges such as recurrence and low response rates persist. Antibody-drug conjugates (ADCs) have emerged as a promising therapeutic approach for various cancers, although their application in UC is currently limited. This review focuses on recent research regarding ADCs designed to treat UC by targeting human epidermal growth factor receptor 2 (HER2), a surface antigen expressed on tumor cells. ADCs comprise three main components: an antibody, a linker, and a cytotoxic payload. The antibody selectively binds to tumor cell surface antigens, facilitating targeted delivery of the cytotoxic drug, while linkers play a crucial role in ensuring stability and controlled release of the payload. Cleavable linkers release the drug within tumor cells, while non-cleavable linkers ensure stability during circulation. The cytotoxic payload exerts its antitumor effect by disrupting cellular pathways. HER2 is commonly overexpressed in UCs, making it a potential therapeutic target. Several ADCs targeting HER2 have been approved for cancer treatment, but their use in UC is still being tested. Numerous HER2 ADCs have demonstrated significant growth inhibition and induction of apoptosis in translational models of HER2-overexpressing bladder cancer. Ongoing clinical trials are assessing the efficacy and safety of ADCs targeting HER2 in UC, with the aim of determining tumor response and the potential of ADCs as a treatment option for UC patients. The development of effective therapies with improved response rates and long-term effectiveness is crucial for advanced and metastatic UC. ADCs targeting HER2 show promise in this regard and merit further investigation for UC treatment.

A pharmacovigilance study on antibody-drug conjugate (ADC)-related neurotoxicity based on the FDA adverse event reporting system (FAERS).

Background: Antibody-drug conjugates (ADCs) are a relatively new class of anticancer agents that use monoclonal antibodies to specifically recognize tumour cell surface antigens. However, off-target effects may lead to severe adverse events. This study evaluated the neurotoxicity of ADCs using the FDA Adverse Event Reporting System (FAERS) database. Research design and methods: Data were extracted from the FAERS database for 2004 Q1 to 2022 Q4. We analysed the clinical characteristics of ADC-related neurological adverse events (AEs). We used the reporting odds ratio (ROR) and proportional reporting ratio (PRR) for the disproportionality analysis to evaluate the potential association between AEs and ADCs. Results: A total of 562 cases of neurological AEs were attributed to ADCs. The median age was 65years old [(Min; Max) = 3; 92]. Neurotoxic signals were detected in patients receiving brentuximab vedotin, enfortumab vedotin, polatuzumab vedotin, trastuzumab emtansine, gemtuzumab ozogamicin, inotuzumab ozogamicin, and trastuzumab deruxtecan. The payloads of brentuximab vedotin, enfortumab vedotin, polatuzumab vedotin, and trastuzumab emtansine were microtubule polymerization inhibitors, which are more likely to develop neurotoxicity. We also found that brentuximab vedotin- and gemtuzumab ozogamicin-related neurological AEs were more likely to result in serious outcomes. The eight most common ADC-related nervous system AE signals were peripheral neuropathy [ROR (95% CI) = 16.98 (14.94-19.30), PRR (95% CI) = 16.0 (14.21-18.09)], cerebral haemorrhage [ROR (95% CI) = 9.45 (7.01-12.73), PRR (95% CI) = 9.32 (6.95-12.50)], peripheral sensory neuropathy [ROR (95% CI) = 47.87 (33.13-69.19), PRR (95% CI) = 47.43 (32.93-68.30)], polyneuropathy [ROR (95% CI) = 26.01 (18.61-36.33), PRR (95% CI) = 25.75 (18.50-35.86)], encephalopathy [ROR (95% CI) = 5.16 (3.32-8.01), PRR (95% CI) = 5.14 (3.32-7.96)], progressive multifocal leukoencephalopathy [ROR (95% CI) = 22.67 (14.05-36.58), PRR (95% CI) = 22.52 (14.01-36.21)], taste disorder [ROR (95% CI) = 26.09 (15.92-42.76), PRR (95% CI) = 25.78 (15.83-42.00)], and guillain barrier syndrome [ROR (95% CI) = 17.844 (10.11-31.51), PRR (95% CI) = 17.79 (10.09-31.35)]. The mortality rate appeared to be relatively high concomitantly with AEs in the central nervous system. Conclusion: ADCs may increase the risk of neurotoxicity in cancer patients, leading to serious mortality. With the widespread application of newly launched ADC drugs, combining the FAERS data with other data sources is crucial for monitoring the neurotoxicity of ADCs. Further studies on the potential mechanisms and preventive measures for ADC-related neurotoxicity are necessary.

MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32β–major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients’ skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

The SpyCatcher-SpyTag interaction mediates tunable anti-tumor cytotoxicity of NK cells

Chimeric antigen receptor (CAR)-modified T and NK cell immunotherapy is a promising approach for cancer treatment. Due to the lack of tunability in anti-tumor activity, conventional CAR therapies have limited efficacy at low tumor antigen densities. To tune the CAR response to tumor cell surface antigens, we have developed a split CAR using the SpyCatcher-SpyTag system. The SpyCatcher serves as the ectodomain to constitute a SpyCatcher-CAR (SpyCAR), while SpyTag is attached to the antibodies that recognize tumor antigens. With dimerization mediated by SpyCatcher and SpyTag, the number and activation level of SpyCARs recruited by tumor antigens depends on the SpyTag number in the “antibody-SpyTag” fusion protein. The results demonstrated that the increasing number of SpyTags effectively enhanced the cytotoxicity of SpyCAR-NK92 cells against target cells. The development of SpyCAR with tunable cytotoxicity provides a novel strategy for CAR-based tumor immunotherapies.

CD22 is a potential target of CAR-NK cell therapy for esophageal squamous cell carcinoma

BackgroundChimeric antigen receptor NK (CAR-NK) cell therapy is one of the most promising immunotherapies. Although it has shown a significant therapeutic effect in hematologic malignancies, few successes have been obtained in solid tumors including esophageal squamous cell carcinoma (ESCC). The major reasons are lack of specific cell surface antigens and complex tumor microenvironment. Here we identify CD22, a well-known tumor surface marker in hematologic malignancies, is expressed in ESCC, possibly serving as a potential target of CAR-NK cell therapy.MethodsThe expression of 13 tumor cell surface antigens used clinically was analyzed in patients from The Cancer Genome Atlas (TCGA) database. Also, mRNA expression were detected in 2 ESCC cell lines and 2 patients samples by qCPR. Then according to Venn diagram, CD22 was selected for further investigation. Following this, the expression of CD22 by immunofluorescence (IF) in ESCC cell lines and by immunohistochemistry (IHC) in 87 cases of human ESCC samples was detected respectively. On the basis of H-score results, the correlation between CD22 expression and clinical parameters was analyzed. As a proof, the efficacy of CD22-targeted CAR-NK cells against ESCC cell lines was performed by a real-time cell analyzer (RTCA) platform.ResultsKYSE-140 and KYSE-150 cell lines displayed surface expression of CD22. IHC showed an 80.46% (70/87) positive rate in ESCC patient samples. Among these, cell membranous expression of CD22 was observed in 27.59% (24/87) patient samples. Through chi-square test, expression of CD22 in ESCC was associated with lymph node metastasis while it was no related to the depth of tumor invasion and clinical stage. Engineered CD22-targeted CAR-NK cells exhibited inhibitory growth capability against ESCC cell lines (p < 0.0001).ConclusionsCD22 is a potential tumor surface antigen capable of being targeted by CAR-NK cells in ESCC. And potential therapeutics for ESCC may be developed based on immune cells expressing anti-CD22 CAR. The study also indicates that CD22 CAR-NK cells could be used in other cancers and more in vivo experiments are needed.

Expression of programmed cell death-1 on neuroblastoma cells in TH-MYCN transgenic mice.

Immunotherapy may improve the poor prognosis of high-risk neuroblastoma. Programmed cell death-1 (PD-1) is expressed in several cancers. The tyrosine hydroxylase MYCN (TH-MYCN) transgenic mouse model is widely used in neuroblastoma research, but detailed information on its immunological background is lacking. Therefore, we studied the immunological tumor microenvironment and tumor cell surface antigen expression in homozygote and hemizygote mice and effects of antibody therapy against PD-1. CD4, CD8, CD11b, and CD11c expression in immune cells from retroperitoneal lymph nodes and spleen was analyzed by flow cytometry. Tumor cell surface antigen expression was confirmed, and data from homozygote and hemizygote mice were compared. Effects of anti-PD-1 antibody were evaluated. CD4-, CD8-, CD11b-, and CD11c-positive cells were not significantly different in homozygote and hemizygote mice, and CD11b- and CD11c-positive cells were identified in the tumor microenvironment in both. Tumor cells expressed PD-1, and anti-PD-1 antibody had anti-tumor effects and significantly reduced the percentage of living tumor cells in cultures after 2h. The immunological background is similar in homozygote and hemizygote TH-MYCN transgenic mice, and both have PD-1-positive tumor cells. Anti-PD-1 antibody suppresses tumor growth. This mouse model may be a useful for studying immunotherapy of neuroblastoma.

USA EXPERIENCE: IN-HOUSE PREPARATION: PROSPECTS AND PROBLEMS

Adoptive Cellular Therapy (ACT) is transitioning from experimental to standard of care. Limited specificities of chimeric antigen receptor T cells (CAR-T) are licensed drugs, with commercial products selling for ∼400,000 USD. Tumor infiltrating lymphocytes (TIL) can target multiple cell surface and intracellular tumor antigens. TIL have not been commercialized, due to complex logistics and cost. Our objective is to leverage a single standardized platform (Miltenyi Prodigy) for in-house ACT. We currently manufacture CD19 CAR-T under an FDA IND and are developing a virtually identical TIL protocol minus the lentiviral vector. TIL are manufactured from malignant pleural effusions rich in immune infiltrates. CD4+ and CD8+ cells are enriched and activated with anti-CD3/CD28 beads. CAR-T are transduced, and both CAR-T and TIL are expanded (IL-7/IL-15) for 5 days. The product is infused fresh, avoiding losses associated with cryopreservation and thawing. Developing and validating release tests (absence of replication competent virus, vector copy number, chimeric antigen receptor expression, endotoxin testing) posed an initial challenge. Having completed assay development, our manufacturing process, including release testing, can be performed for less than 1/10 the cost of commercial CAR-T. We expect that the platform that we have validated will be easily transitioned to new chimeric antigen receptor designs and specificities and will likewise be adaptable to TIL manufacture for the wide variety of cancers that metastasize to the pleura of peritoneum. Standardized in-house ACT manufacture may greatly reduce the cost of cellular immunotherapies, making it more widely available to patients.

Targeting cathepsin B by cycloastragenol enhances antitumor immunity of CD8 T cells via inhibiting MHC-I degradation

BackgroundThe loss of tumor antigens and depletion of CD8 T cells caused by the PD-1/PD-L1 pathway are important factors for tumor immune escape. In recent years, there has been increasing...

LAMTOR1 degrades MHC-II via the endocytic in hepatocellular carcinoma.

Tumor cell surface antigen recognition is a major hallmark of cancer therapy, and loss of major histocompatibility complex class I (MHC-I) is the most common mechanism that impairs tumor cell surface antigen processing and expression. In addition to this, MHC-II regulates antigen presentation in CD4+ T cell immune responses involved in tumor killing by CD8+ T cells, whereas the regulation of endocytosis regulating MHC-II antigen presentation has not been reported. Therefore, the regulation of the endocytosis pathway on the expression of MHC-II surface level and antitumor T cell response remains to be explored. In this experiment, we found that LAMTOR1 regulates the endocytic pathway through the GTPase domain of DNM2 and triggers the formation of autophagosomes. We performed flow cytometry and western blotting analyses, which revealed that the expression of MHC-II molecules on the surface of cells is influenced by LAMTOR1 through the endocytic pathway. We showed that the expression of MHC-II molecules, which recognize CD4+ T cells on the surface of cells, was regulated by LAMTOR1 through an endocytic pathway. By coculture experiments, we showed that CD8+/CD4+ T cells exhibit substantially higher levels of tumor cell apoptosis than those observed when hepatocellular carcinoma (HCC) cells were cocultured with CD8+ T cells alone. This study revealed that LAMTOR1 decreases the expression levels of MHC-II on cell surfaces in order to reduce antigen expression, leading to a decrease in antitumor T cell responses.

Abstract 2016: Preclinical evaluation of uPARAP (MRC2) antibody-drug conjugates (ADCE-003,010,011) in osteosarcoma pdx models

Abstract Introduction: Antibody-drug Conjugates (ADCs) targeting differentially expressed tumor cell-surface antigens show robust clinical activity in several solid tumor cancers, but none is yet available for osteosarcoma. Due to the high unmet medical need in this indication, there is an urgent requirement to identify respective osteosarcoma cell-surface antigens and evaluate the antitumor activity of an ADC that can deliver tailored cytotoxic payloads to osteosarcoma tumors expressing these targets. Methods: We used an integrated proteomic and transcriptomic surfaceome profiling approach to identify cell-surface proteins that are highly expressed in osteosarcoma but minimally expressed on normal tissues. uPARAP (MRC2) was found to be enriched in osteosarcoma at both protein and mRNA levels. The cell-surface expression of uPARAP (MRC2) was further validated by IHC and flow cytometry with osteosarcoma cell lines, PDX models, and patient tumor tissue microarray. As a proof of concept, three MRC2 targeted ADCs with different Microtubulin- and alkylating agent types of payloads were tested in 8 osteosarcoma PDX models. uPARAP (MRC2) ADC, control ADC, or vehicle control was administered IV to mice harboring flank tumors at a dose of 3mg/kg, weekly X 3 (ADCE-003), 2mg/kg on Day 1 (ADCE-010), and 10mg/kg weekly X 2 (ADCE-011). EFS for treatment (T) and control (C) groups, minimum relative tumor volume (minRTV), and objective response measures were analyzed. Results: Western blotting confirmed the expression of uPARAP (MRC2) in 8 osteosarcoma cell lines and 8 PDX models. Flow cytometry further validated cell-surface localization and expression levels of uPARAP (MRC2) in 7 osteosarcoma cell lines. We then performed immunohistochemistry (IHC) staining using an osteosarcoma tissue microarray from 37 patients and 19 PDX models. uPARAP (MRC2) was expressed in 97% of the patient samples and 95% of the PDXs. 51% of the patient samples and 39% of the PDXs had an overall H-score of 100 or higher. Mice tolerated ADCs well with minimal toxicity. All 3 ADCs significantly prolonged EFS in 6/8 osteosarcoma models. Complete response (CR) or maintained CR were observed in 2 models in ADCE-010 and ADCE-011 groups, respectively. Conclusions: uPARAP (MRC2) is highly expressed in most osteosarcoma samples, which makes it a viable target for respective antigen targeting ADC therapies. Three uPARAP (MRC2) targeting ADCs showed antitumor activities in osteosarcoma preclinical models which warrant further investigation of uPARAP targeting ADC therapies for osteosarcoma. Citation Format: Yifei Wang, Wendong Zhang, Zhongting Zhang, Xiangjun Tian, Rossana Lazcano, Pooja Hingorani, Michael Roth, Jonathan Gill, Douglas Harrison, Zhaohui Xu, Jing Wang, Niels Behrendt, Christoffer F. Nielsen, Lars H. Engelholm, Richard Gorlick. Preclinical evaluation of uPARAP (MRC2) antibody-drug conjugates (ADCE-003,010,011) in osteosarcoma pdx models [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 2016.

AFM24 in combination with atezolizumab in patients with advanced EGFR-expressing solid tumors: Phase 1/2a study design and rationale.

TPS2673 Background: Innate Cell Engagers (ICE) are bispecific molecules that bind both a tumor cell-surface antigen and to CD16A expressed on natural killer (NK) cells and macrophages, inducing antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP), respectively. As epidermal growth factor receptor (EGFR) is often overexpressed in several types of solid tumors, this provides an ideal tumor-cell surface antigen which may be targeted using ICE molecules. AFM24 is a first in class, tetravalent, bispecific, novel ICE targeting EGFR. By binding to EGFR on tumor cells and CD16A on innate immune cells, AFM24 may utilize a patient’s innate immunity to induce ADCC/ADCP towards tumor cells. Anti-programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors, which enhance the anti-tumor activity of a patient’s adaptive immunity, have also demonstrated efficacy as monotherapy and are playing an increasingly prominent role in treatments. The combination of AFM24 and the PD-L1 inhibitor, atezolizumab, may therefore represent a rational new treatment modality, enhancing both the innate and adaptive immune responses to target EGFR+ tumor cells. Methods: An ongoing Phase 1/2a open-label, non-randomized, multicenter, dose escalation (Phase 1) and dose expansion (Phase 2a) study was initiated in November 2021 (NCT05109442) to evaluate the safety, tolerability and efficacy of AFM24 in combination with atezolizumab. The primary aim of the Phase 1 study is to determine the maximum tolerated dose and the recommended Phase 2 dose (RP2D) of AFM24. Eligible patients must have advanced histologically confirmed EGFR+ disease and confirmed disease progression after treatment with ≥1 prior therapy. Patients undergo a safety lead-in phase with AFM24 as a single agent 7 days before receiving the combination therapy. A standard 3+3 design will be used to determine the RP2D. Escalating doses of AFM24 will be given to each cohort as weekly intravenous (IV) infusions; the starting dose and at least two planned dose escalations are based on results from the ongoing AFM24 monotherapy trial (NCT04259450). Atezolizumab will be given at a fixed dose of 840 mg as a biweekly IV infusion. Patients will receive AFM24 and atezolizumab treatment until disease progression, intolerable toxicity, patient withdrawal, or termination at the investigator’s discretion. The Phase 2a study will then establish the overall response rate (as per RECIST v1.1) and safety of combination therapy in patients with advanced/ metastatic, or treatment refractory gastric, esophagogastric, hepatocellular, hepatobiliary, pancreatic, or non-small cell lung cancer. For both phases, secondary endpoints include treatment-emergent adverse events, serious adverse events, pharmacokinetics, pharmacodynamics, and immunogenicity. Clinical trial information: NCT05109442.

The combination of CD16A/EGFR innate cell engager, AFM24, with SNK01 autologous natural killer cells in patients with advanced solid tumors.

TPS2675 Background: Natural killer (NK) cells are a critical component of the innate immune system involved in the eradication of transformed cells via antibody-dependent cellular cytotoxicity (ADCC). For treatment of solid tumors autologous NK cell transfer represents a promising treatment strategy, with ex vivo expansion and activation enhancing the specificity and anti-tumor activity of NK cells. The efficacy of this approach may be enhanced through the addition of tumor-targeting antibodies, augmenting NK cell-mediated ADCC. Innate Cell Engagers (ICE) are bispecific antibodies that target a tumor cell-surface antigen and bind to CD16A expressed on NK cells. AFM24 is a novel ICE that targets epidermal growth factor receptor (EGFR), which is often overexpressed in solid tumors. The Phase 1 study of AFM24 monotherapy showed patients had a manageable safety profile, and SNK01 monotherapy has also shown to be well-tolerated in patients with rapidly progressive solid tumors. This study seeks to investigate AFM24 in combination with SNK01 autologous NK cells in patients with advanced EGFR+ solid tumors. Methods: An ongoing Phase 1/2a open-label, non-randomized, multicenter, dose escalation (Phase 1) and dose expansion (Phase 2a) study was initiated in November 2021 (NCT05099549) to evaluate the safety, tolerability and efficacy of AFM24 in combination with SNK01 NK cells in EGFR+ solid tumors. The primary aim of the Phase 1 study is to determine the maximum tolerated dose and/or recommended Phase 2 dose (RP2D) of AFM24 in combination with SNK01 at a fixed dose NK cells using a standard 3+3 design. Eligible patients must have advanced or metastatic disease with positive immunohistochemical staining for EGFR in &gt;1% of tumor cells and be refractory to standard-of-care treatment. Treatment begins with a safety lead-in phase with a single dose of AFM24 7 days prior to combination therapy. AFM24 will be administered at an escalating dose as weekly intravenous (IV) infusions; the starting dose (160 mg) and dose escalations for each cohort are based on results from the ongoing AFM24 monotherapy trial (NCT04259450). SNK01 NK cells will be given at a fixed dose (4.0 x109 cells) as a weekly IV infusion concomitantly with AFM24. Patients will receive combination therapy until disease progression, intolerable toxicity, patient withdrawal or termination at the investigator’s discretion. Phase 2 will then establish the overall response rate (as per RECIST v1.1) of combination therapy in patients with treatment refractory, advanced or metastatic squamous cell carcinoma of the head and neck, non-small cell lung cancer, or colorectal cancer as the primary endpoint. Efficacy will also be assessed by assessing progression-free and overall survival. Secondary endpoints for both phases include treatment-emergent adverse events, serious adverse events, pharmacokinetics and immunogenicity. Clinical trial information: NCT05099549.

A Novel Immunotherapy for Relapsed or Refractory Myeloma

Bispecific therapeutic antibodies are active in relapsed B-cell malignancies by dual engagement of a tumor cell surface antigen and CD3 on T-cells,

Abstract 312: Targeted NanoSpheres (TNS)

Abstract The tumor-targeted, nanoparticle delivery technology has shown the possibility of increasing the delivered dose of virtually any small therapeutics to tumor cells while limiting the drug uptake by normal tissues, thereby greatly increasing the effective MTD. By refining the early formulations and after extensive testing, we developed a novel targeted liposomal nanoparticle, Targeted NanoSpheres (TNS). We showed this novel nano-formulated platform can overcome many deficiencies of conventional nanoparticles and therefore has enhanced potential as an effective delivery vehicle for virtually any type of cancer for which a suitable tumor cell surface antigen is present. We have developedNV103, a first-in-class anti-CD99 TNS (CD99-TNS/Irinotecan), for the treatment of Ewing Sarcoma (EWS), a highly lethal pediatric and young adult bone and soft tissue tumor driven by a fusion protein, typically EWS/FLI1 in over 85% of cases. Cancer cells have the ability to develop resistance to the chemotherapy. Our present salvage/rescue study with NV103 showed that NV103 can overcome irinotecan resistance of Ewing tumor with simple change of dose schedule (dose intensification), not increasing the dose. The results from our salvage/rescue studies with NV103 suggested that successful dose intensification schedules with NV103 could be used to treat relapsed or resistant patients in future clinical trials. Furthermore, Targeted Nanosphere (TNS) can be used to overcome drug resistance of various cancers.This platform is also being investigated for other types of cancer that either express CD99, or other tumor antigens like GD2 and B7-H3. Citation Format: HyungGyoo Kang, Jon Nagy, Bryon Upton, Racheal Upton, Timothy Triche, Timothy Triche. Targeted NanoSpheres (TNS) [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 312.

Immunotherapy-induced antibodies to endogenous retroviral envelope glycoprotein confer tumor protection in mice.

Following curative immunotherapy of B16F10 tumors, ~60% of mice develop a strong antibody response against cell-surface tumor antigens. Their antisera confer prophylactic protection against intravenous challenge with B16F10 cells, and also cross-react with syngeneic and allogeneic tumor cell lines MC38, EL.4, 4T1, and CT26. We identified the envelope glycoprotein (env) of a murine endogenous retrovirus (ERV) as the antigen accounting for the majority of this humoral response. A systemically administered anti-env monoclonal antibody cloned from such a response protects against tumor challenge, and prophylactic vaccination against the env protein protects a majority of naive mice from tumor establishment following subcutaneous inoculation with B16F10 cells. These results suggest the potential for effective prophylactic vaccination against analogous HERV-K env expressed in numerous human cancers.

Research Advances in the Treatment of B-Cell Acute Lymphoblastic Leukemia Based on Surface Antigen Expression --Review

B-cell acute lymphoblastic leukemia (B-ALL) is a common malignant tumor in hematopoietic system. Although the remission rate of the patients with adult B-ALL is similar to those with childhood B-ALL, the rate of long-term disease-free survival (DFS) rate is significantly lower, once recurrence, the remission rate of routine chemotherapy is low and the prognosis is so poor. Based on the expression of tumor cell surface antigens(such as CD19, CD20 and CD22), the specific monoclonal antibodies, bispecific antibodies and chimeric antigen receptor T cells (CAR-T), and other targeted immunotherapy can greatly improve the efficacy of B-ALL patients, especially for patients with relapse and refractory. In this review, the progress of immunotherapy against B-ALL cell surface antigen is summarized briefly.

Generation of a Novel Mesothelin-Targeted Oncolytic Herpes Virus and Implemented Strategies for Manufacturing.

Background: HER2-based retargeted viruses are in advanced phases of preclinical development of breast cancer models. Mesothelin (MSLN) is a cell-surface tumor antigen expressed in different subtypes of breast and non-breast cancer. Its recent identification as a marker of some triple-negative breast tumors renders it an attractive target, presently investigated in clinical trials employing antibody drug conjugates and CAR-T cells. The availability of MSLN-retargeted oncolytic viruses may complement the current immunotherapeutic panel of biological drugs against HER2-negative breast and non-breast tumors. Methods: A fully virulent, tumor-targeted oncolytic Herpes simplex virus-1 (MSLN-THV) with a selectivity for mesothelin-expressing cancer cells was generated. Recombineering technology was used to replace an essential moiety of the viral glycoprotein D with antibody fragments derived from clinically validated MSLN monoclonal antibodies, and to allow IL12 cargo expression in infected cells. Panels of breast and female reproductive system cell lines were used to verify the oncolytic potential of the viral constructs. A platform for production of the retargeted viruses was developed in HEK 293 cells, providing stable expression of a suitable chimeric receptor. Results: We demonstrated the selectivity of viral infection and cytotoxicity by MSLN-retargeted viruses in a panel of mesothelin-positive cancer cells, originating from breast and female reproductive system tumors. We also developed a second-generation oncolytic MSLN-THV, encoding IL12, to enhance the immunotherapeutic potential of the viral backbone. A non-tumor cell line expressing a chimeric MSLN/Nectin-1 receptor, de-sensitized from antiviral responses by genetic inactivation of the Stimulator of Interferon Genes (STING)-dependent pathway was engineered, to optimize viral yields. Conclusions: Our proof-of-concept study proposes MSLN-retargeted herpesviruses as potential cancer immunotherapeutics for assessments in preclinical models of MSLN-positive tumors, complementing the available panel of oncolytic viruses to HER2-negative breast tumors.