Cell Surface Antigens Research Articles

The T-locus - inspiration and distraction?

The T/t locus was a major focus of study by mouse geneticists during the 20th century. In the 70s, as the study of cell surface antigens controlling transplantation antigens was taking off, several laboratories hypothesized that alleles of this locus would control cell surface antigens important for embryonic development. One such antigen, the embryonal carcinoma F9 antigen was said to be an example. Other antigens were described on sperm and embryos that were said to be controlled by alleles at the T/t complex. These findings were later found to be false. The history of the findings and their refutation is described.

Abstract 13: Discovery and development of T cell receptors targeting MAGE family antigens for adoptive T cell therapy against solid tumors

Abstract Background: T cell receptors (TCRs) recognize epitopes from intracellular and cell surface antigens, enabling targeting of diverse tumor antigen classes including overexpressed, differentiation, cancer-testis antigens, as well as those from driver mutations, frameshift mutations, splice variants, and human endogenous retroviral elements (HERV). Melanoma-associated antigens (MAGE) are highly expressed in various solid tumor types, including melanoma, non-small cell lung cancers (NSCLC), bladder, and head and neck cancers, representing promising targets for TCR-T therapy. However, discovering robust and specific MAGE-reactive TCRs remains challenging due to limited throughput of TCR screening methodologies, and the inherently low frequency of tumor-reactive T cells in tumor samples and peripheral blood. Methods: We employ a proprietary mass-cytometry-based multiplexed tetramer staining approach, TargetScape®, to screen and characterize CD8+ T cells in healthy donors and patients’ samples. Our screening panels contain multiple peptides for MAGE family antigens including A1, C2, and A10. Subsequent single cell sequencing or single cell PCR (scPCR) of identified tumor antigen-specific T cells with high sensitivity enables comprehensive analysis of T cell phenotype, transcriptome, TCR specificity, and paired TCR sequence. TCRs identified through this method are transduced for expression in Jurkat reporter cell lines and their reactivity to corresponding peptides is assessed. Selected TCR candidates are then transduced into primary T cells and evaluated for activation and effector function using a variety of cancer cell lines expressing the corresponding endogenous antigens. Specificity assessment is performed through alanine scans and identification of potential off-target peptides and screening for reactivity. Results: We utilized this approach to discover natural TCRs that target several MAGE family antigens. Through Jurkat reporter screening, we observed specific activation of multiple TCRs in the presence of antigen presenting cells and the peptide initially employed to identify the TCRs. Primary T-cells expressing promising TCR candidates exhibited killing activities and cytokine release when confronted with multiple solid tumor cell lines expressing endogenous levels of the MAGE antigen. Specificity assessment is currently in progress, with preliminary data indicating overall favorable specificity profiles for selected TCRs. Conclusions: Our Deep Immunomics platform enables us to detect, characterize, and validate TCR candidates against highly clinically relevant shared cancer antigens. Leveraging this platform, we identified various natural tumor specific TCRs exhibiting activities against a range of solid tumor cell lines expressing MAGE antigens. Promising candidates are currently undergoing in vivo efficacy studies. Citation Format: Juliana Velez Lujan, Hannah Fields, Kan Xing Wu, Yovita Purwanti, Emily Xin Zi Tang, Michael Cordeau, Kathleen Mendez, Melissa Wirawan, Michael Fehlings, Katja Fink, Zilei Liu, Daniel MacLeod. Discovery and development of T cell receptors targeting MAGE family antigens for adoptive T cell therapy against solid tumors [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 13.

Abstract 3616: In vivo expansion patterns of anti-BCMA CAR T-cell in relapsed/refractory multiple myeloma: Comparative immunomonitoring of idecabtagene vicleucel and ciltacabtagene autoleucel

Abstract Introduction: Chimeric antigen receptor (CAR) T cell (CAR-T) treatments have revolutionized the treatment of multiple myeloma (MM). Two CAR-T cell products targeting B cell maturation antigen (BCMA) have received approval for the treatment of MM: idecabtagene vicleucel (idecel) and ciltacabtagene autoleucel (ciltacel). A comparative analysis of in vivo CAR-T responses in patients receiving these novel cellular therapies has not been performed, especially not in the real-world setting. Methods: We prospectively enrolled 23 MM patients treated with idecel or ciltacel in our study GCCC2043. Blood samples were obtained at apheresis, pre-lymphodepleting (LD) chemotherapy, on days 0, +7, +14, +21, +28 and at +3 months post CAR-T. Samples were stained using BCMA or control CAR detection reagents, monoclonal antibodies against T cell surface antigens, and analyzed using flow cytometry. Results: Baseline clinical characteristics, pre-apheresis and pre-LD absolute lymphocyte counts were comparable between groups. There were no G3 cytokine release syndrome (CRS) events whereas G1/2 CRS and all-grade Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) events were not significantly different between cohorts. The global overall response rate (ORR) was 78.3% (n=18) and 60.9% (n=14) at days 30 and 90, respectively. At +1 month, 72.7% (8/11) of idecel and 83.3% (10/12) of ciltacel cohort had an objective response (p=0.625). There was no statistical ORR difference between idecel and ciltacel cohorts at 3, 6, and 9 months. Two-way ANOVA of CAR-T expansion studies revealed a trend towards an effect of treatment type (p=0.0595). Time to peak CAR-T numbers was significantly shorter for idecel (p=0.0127), however, ciltacel showed a significantly more pronounced CAR-T expansion (p=0.043) and longer persistence. Peak CAR-T expansion was associated with clinical responses across cohorts at +1 (p=0.034) and +3 months (p=0.050). Day +30 responses were indicative of Day +90 and Day +180 responses (p<0.001, p=0.011). There was no difference in CD8+ CAR T cell peak levels, however, CD4+ CAR T cell peak levels were much higher (p=0.019) for ciltacel vs. idecel. Similarly, there were significantly higher (p=0.002) CD4+/CD8+ double-positive CAR-T peak levels in ciltacel vs. idecel patients. There was no significant difference in the distribution of T cell memory subtypes at peak level. Conclusions: We demonstrate here for the first time significant differences in CAR T cell expansion and persistence patterns following infusion of either idacel or ciltacel. Studies are underway at our institution investigating anti-BCMA CAR T cell responses in more detail and larger numbers of patients. Such studies have the potential to identify predictive/prognostic biomarkers and/or lead to further optimization of myeloma-targeting CAR-T. Citation Format: Mehmet Kocoglu, Aaron P. Rapoport, Etse Gebru, Destiny Omili, Daniel Yamoah, Rediet Mulatu, Jean Yared, Nancy M. Hardy, Michael Kallen, Ashraf Z. Badros, Djordje Atanackovic. In vivo expansion patterns of anti-BCMA CAR T-cell in relapsed/refractory multiple myeloma: Comparative immunomonitoring of idecabtagene vicleucel and ciltacabtagene autoleucel [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 3616.

Abstract 5286: M2 to M1 repolarization of tumor-associated macrophages via the lysosomal effect of itraconazole

Abstract Objective: Itraconazole (ITZ), an antifungal agent, has been reported to have tumor agnostic anticancer effects. Previous reports have shown prolonged survival in patients with lung and ovarian cancer who received ITZ. The anticancer mechanisms vary depending on the cancer type and stromal cells. Based on our previous studies, we focused on tumor-associated macrophages (TAMs). Methods: Anti-tumorigenic M1 and pro-tumorigenic M2 macrophages were established from THP-1 cells and their phenotypes were determined based on morphology, cell surface antigens by Western blotting, and secreted proteins by ELISA. Bulk proteomic analysis of cell proteins was conducted using liquid chromatography-tandem mass spectrometry. The viability of CaSki cervical cancer cells was evaluated both in culture with the supernatant and co-culture with M2 macrophages after treatment with ITZ (10-5 M). Single-cell RNA sequencing (scRNA-seq) with surface labeling of M2 macrophages with and without the ITZ was performed. Using LoupeBrowser (10x Genomics, Inc.), ITZ-treated M2 macrophages were divided into two groups, one with newly emerged clusters after ITZ treatment (group 1) and the other (group 2). Differentially expressed genes between group 1 and group 2 were identified based on a two-fold and a 0.05 adjusted p value and were subjected to Reactome pathway analysis. Significant pathways were identified based on both p value < 0.05 and FDR <0.3. A triple-labeling immunofluorescence study was conducted to detect cholesterol, IL-1β, and organelles (the endoplasmic reticulum, phagosome, and lysosome). Results: ITZ changed M2 macrophages to M1-like morphology and protein expression. While co-culture with M2 macrophages promoted cancer cell proliferation, both culture with the supernatant and co-culture with ITZ-treated M2 macrophages significantly inhibited CaSki cell growth. scRNA-seq identified newly emerged clusters (group 1) among M2 macrophages following ITZ treatment. Group 1 had elevated mRNA expression of M1 markers, including IL1β, IL6, CD86, TL4, GAPDH, and RKM, compared to group 2. Group 1 expressed the CD86 and TLR4 surface antigen proteins. Pathway analysis identified 176 significant pathways including lysosome vesicle biogenesis. Immunofluorescence analysis showed that M1-like macrophages in ITZ-treated M2 macrophages had enlarged lysosomes containing cholesterol. Conclusion: ITZ repolarized THP-1 derived M2 macrophage to an M1-like phenotype. The mechanism of repolarization involves intracellular cholesterol accumulation via lysosomal dysfunction. Citation Format: Yumi Takimoto, Hiroshi Tsubamoto, Kazuko Sakata, Roze Isono-Taniguchi, Tomoko Ueda, Hiroaki Shibahara. M2 to M1 repolarization of tumor-associated macrophages via the lysosomal effect of itraconazole [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 5286.

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.

Abstract 1905: The ROR1 antibody-drug conjugate, MK-2140, enhances the efficacy of established drugs in preclinical models of pediatric acute lymphoblastic leukemia

Abstract Introduction: Children diagnosed with acute lymphoblastic leukemia (ALL) experience ~90% likelihood of cure. However, the outcome for high-risk ALL and children who relapse remains poor. Receptor tyrosine kinase like orphan 1 receptor (ROR1) is a cell surface antigen primarily expressed in embryonic tissue, but also overexpressed in hematological malignancies. UC961 is a humanized IgG monoclonal antibody with high affinity for ROR1. MK-2140 (Zilovertamab vedotin/VLS-101) and VLS-211 are antibody-drug conjugates (ADCs) of UC961 with monomethyl auristatin-E or PNU payloads, respectively. This study evaluated the in vivo efficacy of MK-2140 and VLS211 against pediatric ALL patient derived xenografts (PDXs). Methods: PDXs were selected based on ROR1 mRNA (RNA-seq) and cell surface (flow cytometry) expression and grown as orthotopic disease in immune-deficient NSG mice. Engraftment and drug responses were assessed by flow cytometric enumeration of the proportion of human versus mouse CD45+ cells in peripheral blood (%huCD45+). Events were defined a priori as the %huCD45+ exceeding 25% or leukemia-related morbidity. MK-2140 (2.5 and 5.0 mg/kg) and VLS-211 (0.25 and 0.5 mg/kg) were administered intravenously, weekly x 3 weeks. Vincristine (0.15 mg/kg once weekly), dexamethasone (5 mg/kg daily x 5) and Lasparaginase (1,250 U/kg daily x 5) (VXL) were administered intraperitoneally for 3 weeks, followed by MK-2140 (5 mg/kg weekly x 3 weeks). Drug efficacy was assessed by event-free survival of treated (T) and control (C) groups and by stringent objective response criteria. In receptor occupancy/pharmacokinetic studies, a single dose of MK-2140 was administered and samples collected for analysis at discrete timepoints thereafter. Results: ROR1 mRNA and cell surface expression showed a significant correlation (R=0.83, P=0.021). MK-2140 significantly delayed disease progression in 4/7 PDXs compared to vehicle control (T-C, -2.6 to 20.0 days). At the highest dose, MK-2140 elicited objective responses (remissions) in two PDXs. VLS-211 significantly delayed disease progression in 5/7 PDXs (TC, -1.8 to 70.5 days), including 3 objective responses. Prior treatment with VXL followed by MK-2140 significantly delayed disease progression compared to VXL alone (T-C, 56.8 versus 35.2 days). MK-2140 bound to ROR1+ cells with near 100% occupancy within two hours of treatment, which was sustained for up to 96 h. Consistent with the receptor occupancy data, plasma levels of MK-2140 were maintained at >100 nM for at least 96 h after a single dose (5 mg/kg). Conclusions: MK-2140 and VLS-211 exerted significant single-agent in vivo activity against a panel of pediatric ALL PDXs. MK-2140 significantly enhanced the efficacy of an induction-type regimen and should be considered for further evaluation in a minimal residual disease setting. Citation Format: Richard B. Lock, Kathryn Evans, Ben Watts, Edward P. Bowman, Steven Neuhauser, Timothy Stearns, Jeffrey H. Chuang, Vivek M. Phillip, Katti A. Jessen, Emily L. Jocoy, Carol J. Bult, Beverly A. Teicher, Malcolm A. Smith. The ROR1 antibody-drug conjugate, MK-2140, enhances the efficacy of established drugs in preclinical models of pediatric acute lymphoblastic leukemia [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 1905.

Abstract 5819: An anti-TROP2-CPT113 ADC, exhibits potent targeted antitumor activity and favorable pharmacokinetic properties

Abstract Trophoblast cell surface antigen 2 (TROP2) is highly expressed in a number of epithelial cancer types and is considered to be a poor prognostic marker. We have developed an anti-TROP2 antibody-drug conjugate, DXC1002, that contains a potent inhibitor of DNA topoisomerase I payload (CPT113) attached to the antibody mainly in the Fab region via a unique hydrophilic CrossConju™ linker. The anti-tumor activities of DXC1002 were studied in various human cancer cell lines and xenograft mouse models and pharmacokinetic profile of DXC1002 were evaluated in cynomolgus monkeys and rats. DXC1002 demonstrated potent anti-tumor activity in TROP2 tumor cells of various expression levels in vitro, and at low dose of 1 mg/kg for one injection, in both high and moderate Trop2 expression xenograft models. In plasma stability studies, wherein DXC1002 was incubated in the plasma of five different species for 168 hours (7 days) at 37 oC, over 90% ADC was intact, exhibiting good stability of the CrossConju™ linker. Pharmacokinetic studies of DXC1002 in monkeys (TROP2 cross-species) and rats (non-TROP2 cross-species) showed half-lives of about 61.27 and 236.77 hours, respectively. Systemic clearance in monkey and rat was 0.41-0.67 and 0.279-0.309 mL/h/kg, respectively. The longer half-lives and slower clearance observed in rats the results offered a more direct assessment of the linker stability as target-mediated clearance played no role in rats. In summary, with the conjugation of a DNA topoisomerase I inhibitor payload to Trop2 antibody via the CrossConju™ linker, DXC1002 demonstrates remarkable anti-tumor properties and pharmacokinetic profile, with a potential to be further validated in clinical applications. Citation Format: Huihui Guo, Xiangfei Kong, Yong Du, Zhicang Ye, Yongxiang Chen, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Zhongliang Fan, Mengmeng Liu, Binbin Chen, Meng Dai, Juan Wang, Miaomiao Chen, Qingliang Yang, Robert Y. Zhao. An anti-TROP2-CPT113 ADC, exhibits potent targeted antitumor activity and favorable pharmacokinetic properties [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 5819.

Abstract 3136: Towards development of a novel biparatopic trop2-ADC

Abstract Background: Trophoblast cell surface antigen 2 (TROP-2) is a member of Tumor-associated Calcium Signal Transducer family (TACSTD2), which is a 35kDa transmembrane protein with 4 N-linked glycosylation sites. The overexpression of TROP2 in various cancers is associated with poor prognosis and increased risk of metastasis. Anti-TROP2 antibody drug conjugates (ADCs) are emerging as an innovative therapeutic intervention for cancer treatment. While these efforts were rewarded by the FDA approval of Trodelvy (Sacituzumab govitecan), a Trop2 targeted ADC, in 2020 for the TNBC patients, tumor heterogeneity could present one of the limitations for the Trop2-targeting therapy, leading to drug resistance. Here, we report our effort in developing a novel biparatopic TROP2 ADC which demonstrate superior cell killing activity compared with the monospecific TROP2 ADC, including certain resistant cell lines for the approved therapy. Methods: Various biparatopic Abs were engineered using two different mAbs targeting the two non-overlapping epitopes of Trop2. The physical stability and biological activities were characterized. Binding competition assay was utilized for epitope binning using SPR. Cell binding affinity was determined using flow cytometry. Cellular internalization activity was measured using Incucyte system, and tumor cell killing efficacy was evaluated in multiple cancer cell lines. CDX mouse models were utilized to investigate the TROP2-ADC in vivo efficacy. Results: We identified a biparatopic TROP2 mAb using two monospecific TROP2 mAbs with A recognizing the same epitope as Trodelvy, and B binding to a non-overlapping epitope vs Sacituzumab’s. mAb-B demonstrates superior ability to recognize a few resistance cell lines to mAb-A. The biparatopic TROP2 mAb-A/B displays a KD of 0.81 nM protein binding compared with 6.42 nM and 0.26 nM, respectively for mAb-A and mAb-B. Importantly, the biparatopic mAb-A/B demonstrates significantly faster cellular internalization activity compared to those of the individual mAbs, signifying the biparatopic scaffold could drive receptor clustering and subsequently enhance the internalization, trafficking to the lysosome and degradation of the target. As expected, the ADC of the biparatopic mAb-A/B conjugated with a TOPi payload shows cancer cell killing efficacy in both in vitro and in vivo experiments. Furthermore, we tested mAb-A, -B and biparatopic mAb-A/B for their binding affinity to 14 missense mutations in TROP2 ECD expressed in HEK293 cells. Interestingly, mAb-A showed decreased binding in 5 mutant cell lines, while mAb-B and biparatopic mAb-A/B maintains activity. Conclusion: We have engineered a novel TROP2 biparatopic antibody with unique biological features as well as superior in vitro and in vivo activities. Such a biparatopic ADC presents its potential to be a best-in-class ADC therapy by overcoming the limitation of the monospecific ADC therapy such as drug resistance. Citation Format: Yinan Wu, Brittany Jiang, Julliet Rivera, Fang Wang, Jing Zhou, Lin Liu, Silvia Hudson, Will Draper, Jennifer Li, Xiaoshan Min, Hang Chen, Zhulun Wang. Towards development of a novel biparatopic trop2-ADC [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 3136.

Abstract 5243: CAR B cells to accelerate antigen presentation in cancer

Abstract Engineered B cells hold promise for multiple therapeutic applications. Walking Fish Therapeutics is engineering B cells to produce replacement proteins for deficiency diseases, antibodies of defined specificity and effector function, and Chimeric Antigen Receptor (CAR) B cells with and without therapeutic payloads for use in the oncology setting. B cells are professional antigen presenting cells (APCs) with the ability to present antigen to CD4+ T cells. Recent studies have found the presence of tumor infiltrating B cells are associated with favorable outcomes across multiple cancer types. Adoptive transfer of B cells has demonstrated antitumor activity in a syngeneic mouse model. B cells from OVA-vaccinated transgenic luciferase mice were adoptively transferred to mice bearing EG7.OVA-tumors. We observed B cells migrating to the tumor and tumor draining lymph node (TDLN), locations where B cells can engage with antigen. Further, we observed a strong anti-tumor response in mice receiving B cells from OVA-vaccinated donors. Based on these results, we hypothesized that B cells engineered to target tumor specific antigens may engage and activate the immune system leading to an enhanced antitumor immune response. We generated CAR B cells expressing synthetic BCRs with tumor-antigen specific scFvs fused to designated B cell signaling motifs. Expression of different CAR constructs were confirmed in both human and mouse B cells. Upon antigen engagement CAR B cells release pro-inflammatory cytokines. Importantly, we demonstrate in vitro that antigen-specific CAR B cells can recognize cognate cell surface antigen, leading to uptake, processing, and presentation on MHCII as detected by activation of peptide-specific CD4+ T cells. When administered in vivo by IV administration, we observed a significant increase in mouse CAR B cells at the tumor site compared to unengineered B cells. We are currently investigating additional CAR formats that may lead to enhanced anti-tumor activity. Citation Format: Mary Ellen Molloy, Jessica Balero, Ana Contreras-Sandoval, Mark Selby, Hangil Park, Srinivas Kothakota, Kathleen Boyle, Rosa Romano, Smrithi Rajendiran, Moises Hernandez, Ariel Pios, Rusty Williams. CAR B cells to accelerate antigen presentation in cancer [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 5243.

Abstract 3212: Development of a Trop2/CD3 bispecific antibody with modulated Trop2 binding affinity as a novel immunotherapy for advanced gastrointestinal cancer treatment

Abstract Trophoblast cell surface antigen 2 (Trop2) is considered as a potential therapeutic target because its over-expression in tumors is found to be associated with poor prognosis of patients with different cancers. Trop2-directed antibody-drug conjugates have been approved for the treatment of solid tumors, however, the expression of Trop2 in a broad range of epithelial tissues, even in low expression, would limit their clinical benefits. The present work generated a novel Trop2/CD3 bispecific antibody with its binding affinity towards Trop2 being well-modulated to mitigate the chance of on-target off-tumor effect. By linking a humanized anti-Trop2 monoclonal antibody with a CD3-binding scFv, a Trop2/CD3 bispecific antibody was produced. In order to adjust the bispecific antibody's affinity to the tumor target, ProABC-2 was used for in-silico paratope prediction (Ambrosetti F et al., 2020). A complementarity-determining residue (CDR) variant was produced and its binding to Trop2 antigen was analyzed using biolayer interferometry. The binding of both wild type (WT) and variant antibodies to Trop2-positive cancer cells, the activation of T cells upon target engagement and the redirection of T cell-mediated killing on cancer cells expressing high level of Trop2 were examined. The binding affinity of CDR variant to Trop2-expressing tumor cells was significantly reduced, which led to a slower induction of cytokines and T-cell proliferation, less acute T-cell activation, and a milder cytotoxic effect. This allowed the bispecific antibody to have a higher level of safety by restricting the cytotoxicity only to cancer cells that expressed high level of Trop2. Our novel Trop2/CD3 bispecific antibody not only showed potent anti-tumor activity, but also demonstrated a lower risk of on-target off-tumor toxicity. Monkey toxicity and other IND-enabling studies are beginning to further bring the drug candidate into clinical trial. Table showing EC50 values of Trop2/CD3 bispecific WT and CDR variant antibodies in different assays WT CDR variant Binding affinity (M) Trop2 4.62E-11 2.14E-10 Cytotoxicity (M) AsPC1 (low Trop2 level) 1.24E-11 No killing effect SW480 (medium Trop2 level) 1.25E-12 2.25E-11 NCI-H596 (high Trop2 level) 5.65E-12 5.89E-10 Receptor occupancy (%) Trop2 0.65 2.75 CD3 0.08 5.83 Cytokine induction (M) IL-2 4.82E-11 5.42E-11 IFNγ 6.46E-13 2.59E-11 T cell activation (M) CD25+ marker 2.02E-12 2.39E-10 CD69+ marker 3.81E-13 7.40E-11 T cell proliferation (M) Ki-67 marker 3.54E-12 8.80E-11 Citation Format: Chui Yee O, Po Yee Wong, Kronos Chow, Kwan Wa Wong, Dennis Wong, John Moon Luk, Kwong Fai Wong. Development of a Trop2/CD3 bispecific antibody with modulated Trop2 binding affinity as a novel immunotherapy for advanced gastrointestinal cancer treatment [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 3212.

Abstract 5760: Intra-tissue quantitative analysis using LC/MS will determine the mechanisms of interstitial pneumonia induced by antibody-drug conjugates

Abstract Background: Antibody-drug conjugates (ADCs) are a new class of therapeutics that combine a monoclonal antibody with a cytotoxic agent (known as their payloads) via a synthetic linker. While ADCs are one of game changer and are the fastest growing classes with novel clinical benefits recently, interstitial pneumonia (ILD) is a clinical problem as a fatal adverse event. However, the mechanism of ADC-induced ILD is under investigation. Purpose: We clarify ADC-ILD mechanism by analyzing released payload distribution in the lung using a novel Trophoblast cell surface antigen 2 (TROP2)-targeting ADC. Material and Methods: TROP2-eribulin is a novel TROP2-targeting ADC composed of the TROP2 antibody and cytotoxic payload eribulin conjugated by a cleavable linker. Four human cancer cell lines (A549, HeLa, NCI-H2110 and SKOV3) and one human- leukemia monocytic cell line (THP-1) were used in this study. Cell surface TROP2 antigen expression was evaluated by flow cytometry. We investigated the concentration and distribution of the TROP2-eribulin and the payload released from the TROP2-eribulin in tumor and lung tissue, using TROP2 low and high expression human cancer xenograft model that were treated with various doses of TROP2-eribulin. The concentration of erbulin was analyzed by liquid chromatograph mass spectrometry, and tissue distribution of ADCs was assessed by immunofluorescence (IF) assay. Results: In vitro analysis showed that the concentration of intracellularly released eribulin was significantly higher in NCI-H2110 with high TROP2 expression compared to A549 with low TROP2 expression (P < 0.05). In vivo analysis, the concentration of released eribulin in tumor tissue was approximately 10-fold higher in the NIC-H2110 xenograft model than the A549 xenograft model, while analysis of lung tissue showed that TROP2-eribulin was distributed in lung tissue in a dose-dependent manner of TROP2-eribulin regardless of TROP2 expression, with significantly more eribulin released in the high-dose group of TROP2-eribulin than in the other dose groups (P < 0.05). IF assay showed that TROP2-eribuilin localized to alveolar macrophages. In the analysis using THP-1 cell, which mimic macrophage function, the concentration of eribulin released from TROP2-eribuilin was significantly reduced by the use of an Fc receptor inhibitor (P < 0.05). Conclusions: Nonspecific uptake of ADC by alveolar macrophages via Fcγ receptors releases cytotoxic payload into lung tissue, regardless of tumor antigen expression levels. This understanding can help elucidate the pathogenesis of ADC-induced ILD. Citation Format: Shigehiro Koganemaru, Hirobumi Fuchigami, Chihiro Morizono, Hiroko Shinohara, Yasutoshi Kuboki, Keiji Furuuchi, Toshimitsu Uenaka, Toshihiko Doi, Masahiro Yasunaga. Intra-tissue quantitative analysis using LC/MS will determine the mechanisms of interstitial pneumonia induced by antibody-drug conjugates [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 5760.

Abstract 3108: Antibody labeling reagents to rapidly screen for the binding and internalization of therapeutic antibodies

Abstract Introduction: There is a growing need in the immunotherapy research field for tools to rapidly screen novel therapeutic antibodies, whether looking for cells expressing IgG, target binding, or tracking internalization. Thermo Fisher Scientific has developed the next generation of Invitrogen™ Zenon™ reagents to enable screening of potential therapeutic antibodies, working across a variety of sample types including primary B cells and hybridomas, while being compatible with a wide range of platforms including flow cytometry, high content imaging, and in-incubator imaging systems. Methods: The Invitrogen™ Zenon™ Alexa Fluor™ Plus IgG Labeling Reagents to screen for antibody binding provide a fast, versatile, and reliable method to evaluate antibody binding to cell surface antigens. Zenon screening reagents are labeled with Invitrogen Alexa Fluor Plus 488, Alexa Fluor Plus 594, or Alexa Fluor Plus 647 dyes (i.e., labeling reagent). The labeling reagent is directed against the Fc portion of an intact mouse or human IgG primary antibody. The formation of the zenon-antibody complex is rapid and requires no purification steps. The Invitrogen™ Zenon™ pHrodo™ Deep Red Labeling Reagents for screening antibody internalization provides a highly sensitive method for monitoring antibody internalization. Zenon pHrodo Deep Red utilizes the same screening reagent as Zenon Alexa Fluor Plus reagents, replacing Alexa fluor dyes with the pH-sensitive dye, pHrodo Deep Red. The pHrodo Deep Red sensors have minimal fluorescence at neutral pH and only upon entry into the late endosome and lysosome do they brightly fluoresce. Zenon pHrodo Deep Red Labeling Reagents are perfectly suited for screening the endocytosis and degradation of potentially therapeutic antibodies including antibody-drug conjugates. Results: Live cells stained with Zenon-labeled antibodies show remarkable signal to background in both flow and imaging applications, while retaining their signal following fixation. Therapeutic antibodies such as anti-Her2 labeled with Zenon pHrodo Deep Red show as bright fluorescent puncta upon lysosomal degradation in the Alexa Fluor 647 channel and co-localize with lysosomal markers such as Invitrogen™ LysoTracker Red dye. Both Zenon Alexa Fluor Plus and Zenon phrodo Deep Red are ideal reagents for screening antibody panels of up to 96 different antibodies. Conclusions: Thermo Fisher Scientific has developed sensitive and rapid Zenon reagents to allow for high throughput therapeutic antibody screening. In addition to Zenon reagents, Thermo Fisher Scientific has developed additional tools that allow for specific monitoring of antibody and protein uptake into the lysosome for degradation. These tools not only greatly improve the workflow from our existing portfolio, but allow for increased sensitivity allowing the field to make decisive decisions when selecting candidate immunotherapies. Acknowledgments: I would like to thank the whole team that worked to develop these new labeling reagents including: Maria Olson and Chris Langsdorf. Citation Format: Ryan W. Holly. Antibody labeling reagents to rapidly screen for the binding and internalization of therapeutic antibodies [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 3108.

Abstract 4086: ABN202 (anti-Trop-2-interferon-beta mutein): A potent antibody-cytokine fusion protein for the treatment of Trop-2 positive solid tumors

Abstract Trop-2, trophoblast cell-surface antigen 2, is a type 1 transmembrane glycoprotein overexpressed in many solid cancers, including breast, lung, pancreatic, bile duct and bladder cancer. Overexpression of Trop-2 in cancer patients is associated with disease progression and poor prognosis. The antibody-drug conjugate (ADC) targeting Trop-2, Sacituzumab-govitecan (Trodelvy®), is approved for patients with triple-negative breast cancer (TNBC) and bladder cancer. However, Trop-2 targeting ADCs exhibit a high frequency of grade 3/4 adverse events and a short duration of response. Therefore, there is an unmet medical need for new treatment strategies beyond ADCs. In a previous study, we designed ABN202 (αTrop-2) to comprise a Trop-2 targeting antibody (Sacituzumab) and IFN-β mutein (ABN102) for the Trop2-positive tumor-specific delivery of ABN102. We confirmed anti-cancer activities of ABN202 against Trop-2 positive bladder cancer. In this study, we evaluated in vitro and in vivo anti-cancer efficacy of ABN202 (αTrop-2) in Trop-2 positive TNBC, bile duct cancer and bladder cancer cell lines. To identify response biomarkers for ABN202 (αTrop-2), we analyzed cell lines exhibiting both response and non-response to ABN202 (αTrop-2). In conclusion, ABN202 (αTrop-2) demonstrated potent anti-cancer efficacy compared to Trodelvy®. Our results support ABN202 (αTrop-2) as a promising drug candidate against Trop2-positive solid tumors. Citation Format: Hee Geon Park, Hyun Kyung Lee, Myeung Ryun Seo, Daa Eun Kim, Sang Beom Bang, Ji Yang Lee, Sung Youl Hong, Kyoung Song, Chan Gyu Lee, Hae Min Jeong, Sae Hyung Lee, Na Young Kim, Jun Young Choi, Young Kee Shin. ABN202 (anti-Trop-2-interferon-beta mutein): A potent antibody-cytokine fusion protein for the treatment of Trop-2 positive solid tumors [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 4086.

Abstract 2606: Targeting mesothelin on tumor cells with a novel, completely human fusion construct delivering the serine protease granzyme B

Abstract Mesothelin is a cell-surface antigen identified as an excellent cancer-associated target upregulated on numerous tumors, including pancreatic and ovarian cancers, as well as mesotheliomas and lung cancers. Granzyme B is a highly cytotoxic serine protease nominally delivered by immune effector cells to target cells, resulting in induction of cell death pathways that are both caspase-dependent and -independent. We developed a fusion protein (GrB-Fc-SD1) composed of GrB and containing SD1, a novel human single-domain antibody that uniquely targets Region III of the mesothelin glycoprotein. The SD1 and GrB domains are tethered by a human IgG heavy chain fragment which enables dimerization. The fusion protein was transiently expressed in HEK-293E cells in serum-free conditions with a final yield of 5 mg/L. Western blot analysis confirmed the expression of this construct as a homodimer. The GrB enzymatic activity in GrB-Fc-SD1 was similar to that of commercially available human granzyme B. ELISA studies confirmed the specific recognition of the SD1 antibody to mesothelin extra-cellular domain. Biacore analysis confirmed binding of GrB-Fc-SD1 with a dissociation constant between 10−7 and 10−8 M. In vitro cytotoxicity against a limited panel of lung, pancreatic and ovarian cancer cell lines expressing surface mesothelin indicate cytotoxicity in the nanomolar range, while cytotoxicity against mesothelin-negative cells was at micromolar levels. Ex vivo serum stability studies showed excellent stability of GrB-Fc-SD1 at both 4°C and -20°C over ninety days and a half-life of approximately three days at elevated temperatures (37°C). In vivo efficacy studies against Capan-2 xenografts in nude mice using both weekly x 5 and QOD x 5 doses of GrB-Fc-SD1 (130 mg/mg total dose, delivered IP) indicated highly significant efficacy in both dose regimens, with p < 0.001 compared to vehicle-treated mice. Mouse body weights were not impacted at the efficacy doses used in this study, indicating that this dose was non-toxic. Histopathology studies revealed a significant decrease in the percentage of Ki-67+ nuclei in treated tumors compared to controls. These data warrant continued investigation of the protein as a therapeutic candidate. Research supported by H2Biologics. Research conducted, in part, by the Clayton Foundation for Research. Citation Format: Khalid A. Mohamedali, Lawrence H. Cheung, Mihai G. Iurascu, Louis R. DePalatis, Claire Thuning-Roberson, Michael G. Rosenblum. Targeting mesothelin on tumor cells with a novel, completely human fusion construct delivering the serine protease granzyme B [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 2606.

Abstract 6757: The anti-tumor efficacy of Th1-specific TROP2 vaccine (AST-07X) in a triple-negative breast cancer murine model

Abstract Background: The trophoblast cell-surface antigen 2 (TROP2) is associated with enhanced tumor proliferation and poor prognosis in breast cancer. TROP2 overexpresses on various epithelial cancer cell surfaces, and is commonly found in prostate, colon, pancreas, lung, and breast cancer. Therefore, anticancer strategy targeting TROP2 may be a potential treatment option for patients with metastatic triple-negative breast cancer (TNBC). Sacituzumab govitecan, a Trop-2-directed antibody drug conjugate (ADC), has shown significant benefits associated with progression-free and overall survival compared to standard chemotherapy for treating metastatic TNBC; however, its toxic effects were more frequent than that of chemotherapy (NCT02574455). In this study, we discovered TROP2 target peptides with T-helper 1 (Th1) polarization and anticancer efficacy. We then evaluated the anti-tumor efficacy of these epitopes and possibility of co-administration with ADC in a TNBC murine model. Materials and Methods: Th1 peptides were identified using the Th-Vac® platform and the predictive binding affinity ranking that indicates potential immunogenicity points of interest for HLA class II. Human peripheral blood mononuclear cell (PBMC) Th1-specific polarization-induced activity and in vivo immunogenicity (Module 2b) were evaluated using flow cytometry and ELISpot analysis. The anti-tumor efficacy of the selected Th1 peptide was evaluated against MDA-MB-23 inoculated athymic Balb/c mice. Each peptide was administered intradermally once weekly for a total of four times at a concentration of 100 μg/head. Sacituzumab govitecan (0.81 mg/kg) was administered intravenously once weekly, for a total of two times. Results: Ten peptides with high affinity for HLA class II were selected, and three epitopes that induce differentiation of T cells secreting TROP2-specific IFN-γ were subsequently selected. These epitopes (p1, p3 and p6) showed tumor growth inhibition efficacy of 52.4%, 38.5%, and 57.2%, respectively, compared to the control (vehicle) group in the TNBC tumor-bearing mice. The cocktail vaccine (AST-07X), which combined these epitopes, was the most dominant at 65.4%. The anti-tumor efficacy of the combination group of the cocktail vaccine and ADC was 77.4% compared with the control group, showing a potent synergistic effect compared to the 46.1% anti-tumor efficacy of the ADC-mono group. Conclusion: AST-07X that induce TROP2-specific Th1 anticancer immune responses, showed sufficient anti-tumor efficacy; these effects were evident under immunodeficient conditions, such as those of TNBC tumor-bearing athymic mice. Synergy effects were also induced via combined ADC administration. We are currently conducting further research on humanized mice to address the limitations of the immunodeficient murine model. Citation Format: Jinho Kang, Hyo-Hyun Park, Jin Kyeong Choi, Seong-Yong Jang, Min-Ah Kim, Myeong-Kyu Park, Ashley Youngmin Kim, Eunkyo Joung, Hun Jung. The anti-tumor efficacy of Th1-specific TROP2 vaccine (AST-07X) in a triple-negative breast cancer murine model [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 6757.

Abstract 5733: Development of a topoisomerase 1 inhibitor platform technology for efficacious and well tolerated ADCs

Abstract Topoisomerase 1 (TOP1) inhibitors are a class of cytotoxic small molecules that have demonstrated effectiveness as therapeutic agents in cancer. However, the broad clinical application has been hindered by poor pharmacokinetic profiles and off-target toxicities. Antibody-drug conjugates (ADCs) enable the targeted delivery of cytotoxic payloads by specifically targeting cell-surface antigens expressed on cancers reducing systemic exposure and toxicity. TOP1-ADCs have received FDA approval for HER2- (trastuzumab-deruxtecan) and Trop2- (sacituzumab-govitecan) expressing solid tumors, demonstrating the promise for this drug class to improve the lives of patients. We have developed a novel drug-linker using a potent TOP1 inhibitor with desirable ADME properties, and a hydrophilic glycoside linker as a platform technology enabling ADCs with favorable physicochemical and biological properties. The TOP1 inhibitor payload was optimized for potency, with reduced P-glycoprotein efflux and enhanced permeability. The hydrophilicity of the linker facilitates the development of highly loaded ADCs (8 drugs/mAb) with high plasma stability, low aggregation, and pharmacokinetics similar to parental antibody. The resultant ADCs are potent and immunologically specific with activity in multidrug-resistant tumor models and bystander activity in heterogenous antigen models. Human cancer cell derived xenograft models demonstrated potent and specific ADC anti-tumor activity with several targets and indications. Improved activity was observed compared to corresponding govitecan- and deruxtecan-based ADCs. ADCs prepared from this drug-linker technology were well tolerated in rats after repeat administration of 60 mg/kg every 4 days for 4 doses. The excellent anti-tumor activity in several models and favorable safety profile demonstrates this platform TOP1 drug-linker technology has the potential for development as ADCs against many cancer targets. Citation Format: Ryan Lyski, Lauren Bou, Johann Sigurjonsson, David Meyer, Calvin Neace, David Ortiz, Katie Snead, Kaleb Smith, Steven Jin, Nicole Stevens, Julia Cochran, Kaveh Alizadeh, Narayana Yeddula, Erica McKinney, Adam Peterson, Lindsay Dotloe, Jessica Simmons, Christopher Carosino, Kim Emmerton, Nancy Everds, Scott Jeffrey, Peter Senter. Development of a topoisomerase 1 inhibitor platform technology for efficacious and well tolerated ADCs [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 5733.

Abstract 1910: Advancing therapeutic interventions for NUT carcinoma: Orchestrating the precision of CRISPR/Cas9-mediated NUTM1 suppression and synergistic ADC strategies

Abstract Purpose: NUT carcinoma (NC) is aggressive carcinoma defined by translocations involving the NUTM1 and frequent squamous differentiation. NUTM1 gene encodes a testicular nuclear protein (NUT), exclusively expressed in the testis. The fusion of NUTM1 leads to abnormal cell growth, resulting in the development of NC. This study aims to discover advanced approaches for inducing the death of cancer cells, specifically targeting those expressing NUT proteins. Methods: Spatial Transcriptome analysis and RNA sequencing were applied to formalin-fixed paraffin-embedded NUTM1 fusion-positive cancer tissues. Virus-like particles were used to introduce CRISPR/Cas9 into cells expressing the NUTM1 fusion oncoprotein. The inhibitory effect was confirmed through multiple in vitro assays. The effectiveness of Anti-Trophoblastic cell-surface antigen (TROP-2) Antibody-Drug Conjugate (ADC) was demonstrated in vivo and in vitro in cells with increased TROP2 expression subsequent to NUT suppression. Results: NCs revealed a relatively uniform pattern of gene expression, forming six unique groups. Notably, the NUT protein predominantly located in the inner regions of the tumor tissues. We employed CRISPR/Cas9 technology to specifically target cells harboring the NUTM1 fusion gene. The precise genetic editing was remarkably effective, achieving up to 90% success in the targeted area. This led to a notable decrease in both RNA and protein levels of NUT expression, effectively disrupting associated downstream pathways. The cell growth rate was reduced in several NC cell lines, and differentiation, accompanied by morphological changes, was observed in most edited cells. RNA sequencing analysis of these edited cells uncovered a substantial increase in expression of cytosolic molecules, with a marked increase in TACSTD2 expression. Interestingly, when we combined this genetic editing approach with a targeted therapy - the TROP2-ADC loaded with interferon-beta - the results were even more striking. Cells treated with this combination showed almost double the rate of growth inhibition compared to those receiving only a single form of treatment. Conclusion: This study provides valuable insights into identifying novel therapeutic targets and elucidating potential mechanisms by analyzing NUT cancer tissues using various assays. Our results support that CRISPR/Cas9-mediated targeting of NUTM1 could be a useful approach for NUT oncoprotein ablation, especially when used in combination with other therapies such as ADCs. Further studies are needed to investigate the efficacy of NUT inhibition in preclinical and clinical settings. the elimination of tumor cells facilitated by CRISPR/Cas9, along with additional tumor markers targeted by ADCs, holds potential for developing treatment strategies against incurable cancers driven by genetic alterations. Citation Format: Juyoung Choi, Hwa Lin Yi, Hee Geon Park, Misook Lee, Daesik Kim, Sung Youl Hong, Young Kee Shin, Yoon-la Choi. Advancing therapeutic interventions for NUT carcinoma: Orchestrating the precision of CRISPR/Cas9-mediated NUTM1 suppression and synergistic ADC strategies [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 1910.

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.

Sex-specific changes in protein expression of membrane transporters in the brain cortex of 5xFAD mouse model of Alzheimer's disease.

Membrane transporters playing an important role in the passage of drugs, metabolites and nutrients across the membranes of the brain cells have been shown to be involved in pathogenesis of Alzheimer's disease (AD). However, little is known about sex-specific changes in transporter protein expression at the brain in AD. Here, we investigated sex-specific alterations in protein expression of three ATP-binding cassette (ABC) and five solute carriers (SLC) transporters in the prefrontal cortex of a commonly used model of familial AD (FAD), 5xFAD mice. Sensitive liquid chromatography tandem mass spectrometry-based quantitative targeted absolute proteomic analysis was applied for absolute quantification of transporter protein expression. We compared the changes in transporter protein expressions in 7-month-old male and female 5xFAD mice versus sex-matched wild-type mice. The study revealed a significant sex-specific increase in protein expression of ABCC1 (p = 0.007) only in male 5xFAD mice as compared to sex-matched wild-type animals. In addition, the increased protein expression of glucose transporter 1 (p = 0.01), 4F2 cell-surface antigen heavy chain (p = 0.01) and long-chain fatty acid transport protein 1 (p = 0.02) were found only in female 5xFAD mice as compared to sex-matched wild-type animals. Finally, protein expression of alanine/serine/cysteine/threonine transporter 1 was upregulated in both male (p = 0.02) and female (p = 0.002) 5xFAD mice. The study provides important information about sex-specific changes in brain cortical transporter expression in 5xFAD mice, which will facilitate drug development of therapeutic strategies for AD targeting these transporters and drug delivery research.

Causal effects of immune cell surface antigens and functional outcome after ischemic stroke: a Mendelian randomization study.

While observational studies link immune cells with post-stroke functional outcome, the underlying immune mechanisms are not well understood. Immune cell surface antigens are actively involved in the biological behavior of immune cells, investigating immune cell surface antigens could deepen our comprehension of their role and biological processes in stroke recovery. Therefore, we aimed to investigate the immunological basis of stroke outcome by exploring the causal relationship between immune cell surface antigens and functional outcome after ischemic stroke in a Mendelian randomization study. Genetic variants related to immune cell surface antigens and post-stroke functional outcome were selected for two-sample Mendelian randomization (MR) analysis. 389 fluorescence intensities (MFIs) with surface antigens were included. Inverse variance weighted (IVW) modeling was used as the primary MR method to estimate the causal effect of exposure on the outcome, followed by several alternative methods and sensitivity analyses. Additional analysis of the association between immune cell surface antigens and risk of ischemic stroke for assessment of collider bias. We found that suggestive associations between CD20 on switched memory B cell (OR = 1.16, 95% CI: 1.01-1.34, p = 0.036) and PDL-1 on monocyte (OR = 1.32, 95% CI: 1.04-1.66, p = 0.022) and poor post-stroke functional outcome, whereas CD25 on CD39+ resting Treg (OR = 0.77, 95% CI: 0.62-0.96, p = 0.017) was suggestively associated with good post-stroke functional outcome. The elevated CD20 on switched memory B cell, PDL-1 on monocyte, and CD25 on CD39+ resting Treg may be novel biomarkers and potential causal factors influencing post-stroke functional outcome.