Antibody-drug Conjugate Targeting Research Articles

Abstract 2620: BCG016, a first-in-class bispecific antibody-drug conjugate targeting 5T4 and MUC1, demonstrates potent preclinical anti-tumor activity

Abstract 5T4 is a highly expressed tumor-associated antigen associated with adverse clinical outcomes in solid tumors, and is an attractive therapeutic target due to low expression on normal adult tissues. While several therapeutic agents targeting 5T4 antigen are currently being evaluated in human clinical trials, none have yet entered the market. Another target, MUC1, is currently under clinical investigation, with most drugs in clinical trials showing limited efficacy due to shedding of the target antigen MUC1-N. 5T4 and MUC1 are commonly co-expressed in various solid tumors, including lung, breast, colorectal and pancreatic cancers, suggesting that targeting both antigens with a single drug could be a promising therapeutic strategy. We previously identified and evaluated antibodies targeting human 5T4 and MUC1-C (cleaved MUC1) using RenLite® fully human common light chain mice. Here, selected antibodies were constructed into 5T4 × MUC1 bispecific antibodies (bsAb). The 5T4-MUC1 bsAb demonstrated high avidity in multiple human tumor cell lines by flow cytometry. Notably, the parental 5T4 antibody also binds strongly to many tumor cell lines. Internalization assays demonstrate that the internalization of 5T4-MUC1 bsAb in breast cancer cells was enhanced compared to the parental anti-5T4 and anti-MUC1 monoclonal antibodies, as measured by Incucyte® live cell imaging. Subsequently, the 5T4-MUC1 bsAb was then conjugated with monomethyl auristatin E (MMAE) to generate 5T4 x MUC1 bsADC (BCG016). Cytotoxicity assays indicate that BCG016 improved tumor cell killing in vitro compared to benchmark ADCs, and in vivo efficacy studies showed superior anti-tumor efficacy of BCG016 in patient-derived NSCLC xenografts compared to benchmark ADCs and parental ADC combination therapy. In summary, we have generated a novel bispecific ADC targeting 5T4 and the cleaved MUC1-C protein, which remains membrane-bound on tumor cells. The 5T4-MUC1 bsADC showed superior anti-tumor efficacy in PDX models and has the potential to be a novel therapeutic for 5T4 and MUC1 co-expressing tumors. Citation Format: Zhenyan Han, Chengzhang Shang, Yifu Zhang, Gao An, Chaoshe Guo, W. Frank An, Yi Yang. BCG016, a first-in-class bispecific antibody-drug conjugate targeting 5T4 and MUC1, demonstrates potent preclinical anti-tumor activity [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 2620.

Abstract 6579: DS-3939a, a novel TA-MUC1-targeting antibody-drug conjugate (ADC) with a DNA topoisomerase I inhibitor DXd, exhibits potent antitumor activity in preclinical models

Abstract Background: Tumor-associated mucin-1 (TA-MUC1) is a tumor-specific transmembrane glycoprotein with aberrant glycosylation. It is highly expressed in various human epithelial cancers, making it an attractive target for cancer therapy. DS-3939a is a TA-MUC1 targeting antibody-drug conjugate (ADC) structurally composed of a humanized anti-TA-MUC1 antibody, an enzymatically cleavable tetrapeptide-based linker, and a DNA topoisomerase I inhibitor (DXd) with a high drug-to-antibody ratio (DAR). In this study, the pharmacological activity of DS-3939a was evaluated using preclinical in vitro and in vivo models. Methods: TA-MUC1 expression was assessed by immunohistochemistry and flow cytometry. Binding specificity of DS-3939a was confirmed by enzyme-linked immunosorbent assay. Induction of DNA damage and apoptosis to cancer cells by DS-3939a treatment were detected by Simple Western System. In vitro cell growth inhibitory and in vivo antitumor activities of DS-3939a were evaluated using various cancer cell lines and patient-derived xenograft (PDX) models. Results: Many specimens across multiple cancer types showed positive staining for TA-MUC1, with a particularly high positive rate observed in bladder, lung, and breast cancers. DS-3939a specifically bound to aberrantly glycosylated MUC1 peptides by recognizing both the glycan and backbone peptide moiety of MUC1. In vitro, DS-3939a inhibited the growth of TA-MUC1-positive cancer cells but not of TA-MUC1-negative cancer cells. Neither a parental anti-TA-MUC1 antibody nor isotype control ADC inhibited the growth of these cells. In addition, treatment with DS-3939a and DXd alone induced DNA damage and apoptosis in cancer cells. These results demonstrate that DS-3939a exhibits TA-MUC1-dependent cell growth inhibition through DXd-mediated cytotoxic effect. Moreover, DS-3939a exhibited significant antitumor effects in the several TA-MUC1-positive cancer cell line-derived xenograft models and various PDX models. DS-3939a also induced strong tumor regression even after treatment of other cytotoxic ADCs in several xenograft models. Conclusion: Based on these preclinical results, DS-3939a could provide valuable therapy with potential benefits for patients with TA-MUC1-expressing tumors. A first-in-human phase 1/2 study in patients with advanced solid tumors is currently in progress (NCT05875168). Citation Format: Mayuko Yukiura, Kohei Takano, Kazuki Takahashi, Akiko Zembutsu, Michiko Kitamura, Yoshinobu Shiose, Kokichi Honda, Kazunori Oyama, Wataru Obuchi, Makiko Yamada, Riki Goto, Ken Sakurai, Kazuyoshi Kumagai, Takashi Kagari, Yuki Abe, Toshinori Agatsuma. DS-3939a, a novel TA-MUC1-targeting antibody-drug conjugate (ADC) with a DNA topoisomerase I inhibitor DXd, exhibits potent antitumor activity in preclinical models [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 6579.

Abstract 1890: HMA800067, a novel CD38-targeting antibody-drug conjugate (ADC), demonstrated superior anti-tumor activity to daratumumab in preclinical B-cell malignancies models

Abstract Introduction: Daratumumab (Dara), an anti-CD38 monoclonal antibody, has been widely used in the treatment of multiple myeloma (MM). However, some of MM patients exhibit primary or acquired resistance to Dara therapy. A CD38 targeting antibody-drug conjugate (ADC) HMA800067 is developed, in which Dara was conjugated with cytotoxic payload via a novel linker, aiming to have superior anti-tumor efficacy to Dara, even in the subjects with resistance to Dara treatment. Methods: HMA800067 was characterized by ELISA-based binding assay, cell internalization assay, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) assays. The in vitro anti-tumor potency was assessed against a panel of 24 MM and B cell lymphoma cell lines with various CD38 expressions. Bystander effect of HMA800067 was evaluated in co-culture of CD38− SU-DHL-2 cells with CD38+ Ramos cells. In vivo anti-tumor efficacy was investigated in the multiple MM and Diffuse Large B-cell Lymphoma (DLBCL) subcutaneous xenograft models, including some non-responsive to Dara. Results: HMA800067 displayed comparable binding affinity and internalization capability to Dara in CD38+ Ramos cells. And HMA800067 maintained the ability of Dara to induce the death of CD38+ Daudi cells by ADCC and ADCP, which indicated that conjugation did not change the property of Dara in the ADC upon antigen binding. HMA800067 exhibited a CD38-dependent cytotoxic activity with median IC50 of 0.46 nM against a panel of tumor cell lines, with a trend that the higher CD38 expression, the stronger potency could be seen. Bystander killing effect of HMA800067 was observed in CD38− cells when co-cultured with CD38+ cells in vitro. Furthermore, with the low release of payload in plasma and sustainable high exposure of payload in the tumor, HMA800067 demonstrated dose-dependent and superior anti-tumor efficacy to Dara in all tested models, and 10 mg/kg induced complete tumor regression in MM RPMI-8226, DLBCL SU-DHL-6 and SU-DHL-10 models. For example, in SU-DHL-6 xenograft model, the treatment of intravenous injection of HMA800067 at 10 mg/kg single dose induced complete tumor regression in all the animals within 10 days of administration, which was maintained until the end of study (day 49), while 10 mg/kg Dara twice a week for 2 weeks inhibited tumor growth within 20%-40% without any tumor regression during a four-week observation post initial dosing. Conclusion: HMA800067 demonstrated potent anti-tumor activities in vitro and in vivo in multiple B-cell malignant tumor lines, including those with poor response to Dara. These results supported further development of HMA800067, as a superior therapeutic option for treatment of patients with CD38+ B cell malignancies. Citation Format: Yan Xu, Junqing Liang, Shuwen Jiang, Haibin Yang, Hui Zhang, Fangfang Mao, Jiahuan Zhu, Jianlin He, Na Yang, Jian Wang, WeiHan Zhang, Yongxin Ren, Weiguo Su. HMA800067, a novel CD38-targeting antibody-drug conjugate (ADC), demonstrated superior anti-tumor activity to daratumumab in preclinical B-cell malignancies models [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 1890.

Abstract 3128: HRA00184-C004, preclinical characterization of a novel tissue factor-targeted antibody-drug conjugate

Abstract The physiological function of tissue factor (TF) is to initiate coagulation cascade by forming complex with plasma Factor VII after vascular injury. For Tisotumab vedotin (Tivdak), a TF targeting antibody-drug conjugate (ADC) approved for the treatment of cervical cancer, bleeding events were prespecified as adverse effects (AEs) of interest, besides ocular toxicity and peripheral neuropathy (known MMAE payload related AE). In order to mitigate the bleeding risk, a next generation of TF-targeting ADC is developed by Hengrui Pharmaceuticals. HRA00184-C004 is a novel ADC comprising a differentiated TF-targeted antibody (HRP07132) conjugated to a proprietary topoisomerase I inhibitor (Dxh, an exatecan derivative) via a protease-cleavable linker. In contrast to most TF-targeting antibodies, the naked HRP07132 does not interfere the interaction between TF and Factor VII or Factor X, has no impact on coagulation function in prothrombin time and thrombin generation assay, therefore reduced bleeding incidence is expected for HRA00184-C004. Meanwhile, HRA00184-C004 exhibited not only potent growth inhibition against multiple TF-expressing cancer cell lines but also bystander-killing effect in vitro. HRA00184-C004 also displayed robust and sustained anti-tumor activities in the PDAC HPAFII (TF high), TNBC MDA-MB-231 (TF moderate) and NSCLC H358 (TF low) TF-expressing xenograft models. Furthermore, in cynomolgus monkey, HRA00184-C004 is well-tolerated over a 6-week period with 12 mg/kg dosing every 3 weeks with acceptable PK profile. Notably, neither coagulation disorder nor skin rash was observed, which are superior to the historical NHP data reported by Tivdak. In conclusion, with the encouraging efficacy in preclinical study and promising safety profiles in NHPs, HRA00184-C004 has demonstrated the best-in-class potential and is scheduled to advance into clinical development. Citation Format: Hanxiao Ying, Lingfeng You, Ning He, Shaoyu Xu, Pu Pu, Sophie Lin, Jun Feng, Zhe Zhang, Xin Ye, Min Hu, Feng He. HRA00184-C004, preclinical characterization of a novel tissue factor-targeted antibody-drug conjugate [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 3128.

Abstract 3142: NN3201, a novel c-Kit targeting ADC, exhibits robust preclinical anti-tumor efficacy in SCLC and GIST models

Abstract c-Kit (CD117) is a type III receptor tyrosine kinase (RTK), which is known to be activated upon binding to its cognate ligand stem cell factor (SCF) to induce critical signaling pathways involved in cell proliferation, survival, and differentiation. Indicative of poor prognosis, overexpression and activating mutations of c-Kit have been implicated in a variety of human cancers including small cell lung cancer (SCLC), gastrointestinal stromal tumors (GIST), and acute myelogenous leukemia (AML). While imatinib, a small molecule c-Kit inhibitor, has been a beneficial treatment for GIST, resistance eventually develops to the drug, moreover, shows limited efficacy in c-Kit overexpressing tumors such as SCLC. Herein, we developed NN3201, a novel c-Kit targeting antibody-drug conjugate (ADC), comprised of fully human 2G4 antibody with a picomolar binding affinity to c-Kit and cytotoxic monomethyl auristatin E (MMAE) as the payload. NN3201 displayed potent in vitro cytotoxicity in various wild-type and mutant c-Kit positive SCLC and GIST cell lines with IC50 in the nanomolar range. In addition, NN3201 was rapidly internalized and inhibited c-Kit-mediated signaling., NN3201 treatment resulted in the increased proportions of the sub G1 and G2/M in the c-Kit positive cancer cell lines, indicating that release of MMAE induced cell cycle arrest. Moreover, bystander effect was confirmed by co-culturing c-Kit high and negative cell lines. Most importantly, in mouse xenograft models, NN3201 showed a remarkable tumor growth inhibition of several wild type, mutant c-Kit positive, and imatinib resistant SCLC and GIST cell lines. Enhanced anti-tumor activity and delayed tumor growth were observed in an SOC-treated (etoposide and carboplatin) SCLC xenograft model, by NN3201 in comparison to second line SOC (topotecan or irinotecan). In the GLP study, repeated intravenous administration of NN3201 was well tolerated at all doses (0.5, 1, 2 mg/kg Q3Wx3) without unscheduled death. Dose-dependent, yet transient, cytotoxicity of NN3201 was observed in the bone marrow. We confirmed HNSTD (Highest Non-Severely Toxic Dose) of NN3201 to be 2 mg/kg through exploratory and GLP repeat dose toxicity studies as no serious irreversible toxicity was observed. Accumulating data suggest that NN3201 is a promising therapeutic alternative for the treatment of SCLC and GIST regardless of wild-type or activating mutations in c-Kit. Citation Format: Chansik Kim, Jin Gu Cho, TaeMin Wi, Jiwoo Moon, Han-Jik Ko, Jina Lee, Jin Woo Park, Yeonjy Lee, Sanghee Kim, Jin-Ock Kim, Jaeyoung Song, Sun-Hwa Lee, Sang Gyu Park. NN3201, a novel c-Kit targeting ADC, exhibits robust preclinical anti-tumor efficacy in SCLC and GIST models [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 3142.

Abstract 6899: Enfortumab vedotin (EV): Efficacy comparison with trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) and its potential for combination benefit in bladder cancer XPDX models

Abstract EV is a Nectin-4 targeting antibody-drug conjugate (ADC) with an MMAE payload, recently approved for bladder cancer treatment. We established and characterized 18 bladder XPDX models representing primary and metastatic disease from naïve or clinically treated patients, some with actionable mutations. To better understand the potential additive benefit of EV in bladder cancer, we evaluated the ADC alone and in combination with agents targeting ERBB2, PIK3CA or FGFR3. In addition, we tested EV alone in ST5420B, a model established from a patient who progressed on EV after five cycles, as well as ST975B, a model which harbors a novel NECTIN4 fusion. 18 bladder XPDX models were established in immune-deficient mice, including 5 from newly diagnosed patients (2 from primary site), and 13 from recurrent disease (2 from primary site). Nectin-4, Trop2 protein and ERBB2 receptor expression was tested, and models profiled using WES and RNAseq. For in vivo studies, all models were evaluated against cisplatin, T-DXd, SG, and EV. Models with actionable mutations were tested with alpelisib, erdafitinib, and neratinib alone and in combination with EV. Endpoints in all studies included tumor volume and time from treatment initiation with %T/C values and tumor regression reported at study completion; a %T/C of ≤ 20% versus control was considered sensitive. Tumor regression (%T/C<0%) versus Day 0 tumor volume was also reported. Most models stained positive for Nectin-4 and Trop-2. FGFR3 variants were found in five models and ERBB2 mutations in two while several models reported PIK3CA variants; deletions in RB1 and CDKN2A were common. In vivo studies reported differential responses to cisplatin with the most sensitive models established from treatment-naïve patients. EV and SG tested alone reported activity in several models; EV added benefit in some combination treatments. We have characterized a panel of bladder XPDX models and benchmarked them against T-DXd, EV and SG alone and EV in combination with targeted therapies. This data is a valuable tool in further developing EV and identifying novel therapies for bladder cancer. Citation Format: Johnnie Flores, Heaven Sessions, Alyssa Simonson, Natalia Banos, Tahmineh Rouzbahani, Armando Diaz III, Jim Lund, Emiliano Calvo, Victor Moreno, Kyriakos Papadopoulos, Drew Rasco, Amita Patnaik, Scott Ulmer, Luis Rodriguez, Michael Wick. Enfortumab vedotin (EV): Efficacy comparison with trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) and its potential for combination benefit in bladder cancer XPDX models [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 6899.

Abstract 1893: OBI-992, a novel TROP2 targeting antibody-drug conjugate, displayed excellent antitumor efficacy in various animal models

Abstract Background: TROP2 is a validated therapeutic target for cancer treatment. OBI-992 is an antibody-drug conjugate (ADC) derived from a novel TROP2 antibody linked with a topoisomerase 1 inhibitor payload, exatecan, through conjugation with an enzyme-cleavable linker. Upon binding to TROP2 on the surface of cancer cells, OBI-992 is internalized into the cell and trafficked to lysosomes where the linker is cleaved by cathepsin B, releasing the payload exatecan to kill the cancer cells. This study aims to evaluate the antitumor efficacy of OBI-992 in vitro and in vivo, including cell-based cytotoxicity, cell line-derived xenografts (CDX), and patient-derived xenografts (PDX) models. Methods: The cytotoxicity of OBI-992 was evaluated in cell lines with different levels of TROP2 expression. In vivo efficacy was evaluated using CDX and PDX models of various cancer types. Bystander killing effect of OBI-992 was examined in a xenograft model containing a premixture of TROP2 positive and TROP2 negative cancer cells. Moreover, the impact of overexpression of P-glycoprotein (Pgp) or breast cancer resistance protein (BCRP) on the antitumor efficacy of TROP-2 ADCs was evaluated. OBI-992 in combination with PARP inhibitors such as olaparib and talazoparib was examined for potential synergistic effects in a homologous recombination deficiency (HRD) xenograft model. Results: The cytotoxicity of OBI-992 was positively associated with the TROP2 RNA levels in different cell lines. In various CDX and PDX models, a single dose of OBI-992 at 3 or 10 mg/kg exhibited remarkable tumor growth inhibition. Notably, the antitumor efficacy of OBI-992 surpassed that of datopotamab deruxtecan (Dato-DXd) across different CDX and PDX models. OBI-992 demonstrated a bystander killing effect as OBI-992 was able to kill TROP2-negative xenografts in the presence of nearby TROP2-positive cells. OBI-992 showed superior efficacy to Dato-DXd in the CDX model overexpressing Pgp or BCRP. These findings suggest that OBI-992 was not affected by the Pgp- and BCRP-mediated multidrug resistance. In the HRD CDX model at suboptimal doses, combination of OBI-992 with olaparib or talazoparib displayed remarkable synergistic effects. Conclusions: OBI-992 exhibited excellent antitumor efficacy and outperformed the benchmark Dato-DXd in CDX and PDX models of various cancer types. A strong bystander killing effect indicated that OBI-992 will be effective for tumors with heterogenous expression of target antigen. OBI-992 retained its antitumor effect upon overexpression of Pgp and BCRP, suggesting that OBI-992 may overcome the multidrug resistance. Outstanding synergistic effect with the combination of OBI-992 with PARP inhibitors was observed. These results warrant further studies of OBI-992 in the clinical setting. Citation Format: Wan-Fen Li, Ming-Feng Chiang, Hao-Cheng Weng, Jhih-Jie Yang, Hsin-Shan Wu, Chun-Jung Lin, Ping-Tzu Chiu, Ming-Tain Lai. OBI-992, a novel TROP2 targeting antibody-drug conjugate, displayed excellent antitumor efficacy in various animal models [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 1893.

Abstract 5089: Therapeutically targeting endometrial cancer by ICAM1 antibody-drug conjugates

Abstract Background: Endometrial cancer is the most frequently occurring gynecologic cancer in developed countries and the third leading cause of cancer deaths among women. It remains one of the few malignant tumors with rapidly increasing mortality and morbidity. Patients with recurrent or metastatic endometrial cancer continue to experience poor outcomes. Antibody-drug conjugates (ADCs) represent a class of targeted therapeutic modalities that offer biomarker-based therapeutic options for patients with endometrial cancer. In this study, we proposed to identify a novel molecular target for the preclinical development of an ADC for endometrial cancer-targeted therapy. Methods: Firstly, to determine the level of target expression within endometrial cancer tissue components as well as differences, we performed immunohistochemical staining of human endometrial cancer and paracancerous tissue. Secondly, the expression of the target on the cell membrane surface was quantitated and qualitatively verified using flow cytometry and single-photon confocal microscopy. In the third step, an endocytosis assay was used to verify the endocytosis of the target antibody by EC cells. Confocal imaging can directly observe the endocytosis of the target antibody, and flow cytometry can be analyzed and quantified. Co-localization experiments with antibody fluorescence can verify the specific site where the target antibody is endocytosed into cancer cells. We then designed and characterized two targeted ADCs. Next, the in vitro inhibitory activities of these ADCs against endometrial cancer cell lines and normal cells were evaluated using the CCK8 assay. Finally, we established a cell line-derived xenograft (CDX) model of endometrial cancer to validate the in vivo efficacy and bio-safety of the ADCs. Results: We have determined a correlation between ICAM1 overexpression and EC, and IHC staining of patient tissues showed significantly higher levels of ICAM1 expression in endometrial cancer tissues than in paracancerous tissues. The high cell surface expression of ICAM1 was verified in a panel of various human endometrial cancer cell lines. Moreover, two ICAM1 ADCs were established using clinically-approved ADC linker and payload combinations. It was visually confirmed that ICAM1 ADCs selectively recognize endometrial tumors and efficiently enter endometrial cells via antigen-mediated endocytosis. We compared the anti-tumor activity of ICAM1 ADCs with standard-of-care chemodrugs, and ICAM1 ADCs outperformed chemodrugs in the CDX model of endometrial cancer without toxicity. Conclusion: We identified that ICAM1 is a promising ADC target for endometrial cancer and confirmed the potent anti-tumor activity and biosafety of ICAM1 ADCs in vitro and in vivo, warranting further pre-clinical and clinical investigations. Citation Format: Hanfei Xie, Lu Sun, ShiLi Yao, Peng Guo, YingLi Zhang. Therapeutically targeting endometrial cancer by ICAM1 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 5089.

Abstract 866: Identification of survival-associated epithelial cell markers linked to TROP2 through single-cell and bulk sequencing analysis

Abstract Introduction: Colorectal Cancer (CRC) is known for its aggressiveness and drug resistance. This has increased the interest in antibody-drug conjugates (ADCs) as a possible therapy. In this study, we aim to investigate the effects of the ADC target TROP2, on the level of epithelial cells and its correlation with survival outcomes in CRC patients. Methods: Single-cell RNA (scRNA) data was downloaded from Gene Expression Omnibus (GEO) for CRC patients and evaluated for TROP2 expression. Patients were grouped into low and high-TROP2 based on median TROP2 expression, and pseudo-bulk analysis was used to find the differentially expressed genes (DEGs). The DEGs were used to find the survival association in the TCGA-CRC cohort. A risk score was built using principal component analysis (PCA) on the TROP2-DEGs and cutoff point was chosen based on survival. Kaplan-Meier curve was used to compare overall survival (OS), progression-free survival (PFS), and disease-free survival (DFS) risk groups. Gene Set Variation Analysis (GSVA) was used to identify the enriched pathways between low- and high-TROP2 in GSE using pseudo-bulk by pooling epithelial cells of individual patients. Results: Of the 10424 cells of 15 different types for 9 CRC patients retrieved from GSE146771, TROP2 was significantly expressed by epithelial cells (n = 766) with mean expression of 1.64 (SD: 1.96, P-value: 0.003) using pseudo-bulk analysis. Three significant DEGs were obtained which are: KIF13B, UCHL3, and PLAC8. These were evaluated for survival association in resectable stages (I-III) CRC patients (n = 419) using PCA to group the patients into low-risk (n = 88) and high-risk (n = 331), using -1.4 as the cutoff point. High risk group showed a better survival with a 1-year survival probability of 94% compared to 90% in the low group and a 5-year survival probability of 74% vs. 46% in the low group. The Kaplan-Meier curve showed that OS, PFS & DFS were significantly better in the low-risk group (p-value = 0.004, 0, 04, and 0.024 respectively). TROP2 and PLAC8 were significantly associated with worse prognosis, whereas UCHL3 was associated with better prognosis (p-value = <0.001), however, KIF3B did not significantly affect the prognosis. APC gene mutation and TP53 were higher in the low-risk group (p-value = 0.004, 0.007 respectively). KRAS-signaling, IL-18-signaling, MET activation of PTK2-signaling were upregulated in high-TROP2 group, while MYC targets, MTORC1 signaling, DNA repair, reactive-oxygen-species signaling, and TCR-signaling were upregulated in low-TROP2. Conclusion: In this study we developed a TROP2-associated risk score that significantly predicted OS, PFS, and DFS in patients with resectable CRC by combining single-cell and bulk-RNA-seq datasets and showing predominant expression of TROP2 in epithelial cells. These findings support the development of TROP2 targeting therapeutics in this space. Citation Format: Noor Nedal Al-Bzour, Ayah Nedal Al-Bzour, Azhar Saeed, Lujia Chen, Anwaar Saeed. Identification of survival-associated epithelial cell markers linked to TROP2 through single-cell and bulk sequencing analysis [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 866.

Abstract 3135: BSI-730, a bispecific antibody targeting HER2 and PD-L1 for the development of a first-in-class bispecific ADC

Abstract Background: Antibody-drug conjugates (ADCs) have become a promising therapeutic option for patients with cancer. Bispecific ADCs targeting two tumor-associated antigens have potential differential anti-tumor advantages. HER2 and PD-L1 are co-expressed in some tumor cell types, such as breast cancer, gastric cancer, lung adenocarcinoma and urothelial carcinoma. A bispecific ADC targeting HER2 and PD-L1 should provide therapeutic benefit, particularly for patients with HER2 low cancer. Dual-target mediated cytotoxicity combined with PD-L1 mediated immunotherapy provides an innovative approach for cancer patients. Experimental procedures: An anti-PD-L1 monoclonal antibody was identified from A/J mice immunized with PD-L1-ECD-Fc and screened by the Biosion proprietary SynTracer® High Throughput Endocytosis Platform. A “knob-in-hole” bispecific antibody, BSI-730, targeting HER2 and PD-L1 was created with trastuzumab and the humanized anti-PD-L1 scFv. Target binding specificity, binding activity, and affinity of BSI-730 were evaluated by protein-based ELISA, cell-based FACS and Biacore-based SPR, and the ligand blocking activity of PD-L1 portion was measured by competitive ELISA and cell-based FACS. The internalization activities on various cancer cell lines with different expression levels of HER2 and PD-L1 were evaluated by using the SynTracer® Platform. Summary: BSI-730, a HER2/PD-L1 bispecific antibody, showed comparable binding affinity to HER2 as compared to trastuzumab, as well as comparable bioactivity to the parental anti-PD-L1 antibody regarding PD-L1 binding and PD-1/PD-L1 blocking. Based on a cell-based reporter assay, BSI-730 was able to reverse PD-L1 mediated T-cell suppression and exhibited comparable potency to the parental anti-PD-L1 antibody. The internalization of BSI-730 on HER2 low cancer cell lines was stronger than that of trastuzumab whereas the internalization of BSI-730 on HER2 high cancer cell lines was comparable to that of trastuzumab. Conclusion: BSI-730 is a novel bispecific antibody for the development of a first-in-class bispecific ADC with the potential advantage of increased potency that can be further investigated to treat HER2 and PD-L1 co-expression tumors, particularly HER2 low tumors. Citation Format: Xiaoyao Hao, Hongyan Li, Xiaodong F. Liu, Jinyu Liu, Wenwen Dai, Ying Pan, Hui-Han Hu, Jun Li, Shukai Xia, Qun Lyu, Hugh M. Davis, Mingjiu Chen, Zeyu Peng. BSI-730, a bispecific antibody targeting HER2 and PD-L1 for the development of a first-in-class bispecific 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 3135.

Abstract 963: Comprehensive epigenomic profiling from plasma to inform therapy selection: A proof-of-concept study in cancer

Abstract BACKGROUND: Analysis of genomic alterations in circulating tumor DNA is gaining traction in clinical oncology and can provide insights into tumor biology without the need for invasive tissue sampling. In addition to genetic alterations, epigenomic reprogramming leads to transcriptional dysregulation and drives cancer phenotypes including molecular subtypes, histologic subtypes, and mechanisms resistance. As current liquid biopsy assays fail to effectively capture transcriptional biology, new approaches are needed to examine the transcriptional status of therapeutic gene targets and pathways including those relevant to rapidly emerging classes such as antibody-drug conjugates (ADC) and radio-conjugates. METHODS: We developed a novel multimodal assay that reveals genome-wide transcriptional activity of promoters, enhancers from chromatin and surveys the DNA methylome using 1ml of patient plasma. We applied this assay to patient plasma samples from across 15 tumor types generating 7000 genome-wide transcriptional profiles. RESULTS: We confirmed a significant correlation between epigenomic signals of transcriptional activation and gene expression from RNA-seq (Promoter vs RNA-seq: ⍴ =0.95, p<0.05; DNA methylation vs RNA-seq: ⍴=-0.16, p<0.05). We identified transcriptional activation in cancer patient plasma of well-established cancer-associated biomarkers (e.g. MET, DLL3, PSMA) in a tumor-specific manner. Epigenomic profiling simultaneously inferred the expression of multiple pertinent ADC targets currently under investigation (MET, HER2, HER3, TROP2, B7H4 in breast cancer), and SLFN11, a known biomarker for sensitivity to these agents. Unlike targeted panels, the platform assesses transcriptional regulation genome-wide, enabling the assessment of transcriptional activity of select genes as well as related pathways. For example, a multimodal classifier robustly predicted HER2 status across metastatic breast cancer plasma samples based on features both within the HER2 amplicon as well as HER2-distal genes that are activated in HER2+ cancers (AUC = 0.93, 0.84-1.0 95% CI). The multimodal classifier out-performed individual analyte-based classifiers (AUCPromoter+Enhancer = 0.85, 0.72-0.98 95% CI; AUCDNA-methylation = 0.69, 0.48-0.90 95% CI). Epigenomic signatures were also used to delineate multiple mechanisms of resistance to androgen receptor signaling inhibition in prostate cancer, including reactivation of the androgen receptor, glucocorticoid signaling bypass, and histological transformation to a neuroendocrine subtype. CONCLUSION: This comprehensive epigenomic liquid biopsy assay provides a platform for simultaneous genome-wide transcriptional assessment of disease and therapy relevant genes and pathways, representing a paradigm shift in our ability to longitudinally monitor cancer in individual patients. Citation Format: Travis Clark, Ji-Heui Seo, Anthony D'Ippolito, Aparna Gorthi, Jonathan Beagan, Jamey Guess, Amy Donahue, Mandy Greene, Alyssa Lau, Fernando Ramirez, Kristian Cibulskis, Hyun-Hwan Jeong, Matthew Davidsohn, Gitanjali Lakshminarayanam, Michael Coyne, Baovy Tran, Tyrone Tamakloe, Hathairat Sawaengsri, Marc Eid, Karl Semaan, Brad Fortunato, Corrie A. Painter, Juliann Chmielecki, Toni K. Choueiri, J Carl Barrett, Geoff Otto, Matthew L. Freedman, Matthew L. Eaton, Sylvan C. Baca. Comprehensive epigenomic profiling from plasma to inform therapy selection: A proof-of-concept study 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 963.

Abstract 5083: Discovery of an asymmetric IgG-like bispecific ADC targeting EGFR/HER3

Abstract Background: The epidermal growth factor receptor (EGFR) family, consisting of EGFR, HER2, HER3, and HER4, plays a critical role in tumorigenesis and tumor progression. Inhibition of ERBBs using either monoclonal antibodies (mAb) or small-molecule tyrosine kinase inhibitors have been approved for use for the treatment of various types of cancers. Despite relative success, many patients acquire resistance to long-term benefit due to alternative compensatory signaling pathways. Accordingly, activating mutations or overexpression of HER3 has been reported in many cancers, such as breast, ovarian, lung, colorectal, melanoma, head and neck, cervical and prostate cancers. Here, we report the discovery of a humanized anti-EGFR x HER3 IgG-like bispecific antibody-drug conjugate (ADC). The ADC takes a asymmetric 1+1 form through HC-HC and HC-LC charge-based heterodimerization, which is then conjugated to a topoisomerase 1 inhibitor (TOP1i) payload via a cleavable linker. The affinity of EGFR and HER3 was optimized to improve the therapeutical window, and has shown potent anti-tumor efficacy in various tumor models with limited toxicity supporting further development in clinic. Methods: An anti-EGFR x HER3 bispecific ADC (PM1300) was generated by introducing unique mutations to the CH1-CL domains of each binding arm to avoid HC-LC mispairing. KIH mutations were also introduced to each CH3 domain to support HC/HC heterodimerization and generate an IgG-like bispecific with one arm binding to EGFR and the other to HER3. TOP1i payload was conjugated to the IgG-like bispecific by the endogenous cysteine residues at DAR 8 via a clearable linker. Results: Through affinity optimization, PM300 was found to preferentially bind to EGFR/HER3 double-positive cells rather than EGFR single-positive cells. PM1300 showed significantly increased internalization and anti-proliferation activity against EGFR/HER3 double-positive cells, with limited activity towards single positive-cells. PM1300 used an optimized linker for better payload release and serum stability. PM1300 induced a potent anti-tumor efficacy in various CDX models representing different EGFR and HER3 expressing levels and mutations. Importantly, PM1300 exhibited a good safety profile in NHP consistent with the optimal affinity for EGFR and HER3. These results demonstrate that PM1300 has a promising efficacy/safety therapeutical window in preclinical models supporting further development in the clinic. Conclusion: A bispecific ADC targeting EGFR x HER3 was discovered, named PM1300, which has an asymmetric 1+1 IgG-like structure and optimized affinity. This allows for preferential binding to EGFR/HER3 double-positive cancer cells, rather than EGFR single-positive cells. This may significantly contribute to minimizing safety risk that is common for EGFR-targeting agents. Citation Format: Liandi Chen, Shaogang Peng, Chao Wang, Xiaoniu Miao, Yao Yan, Jun Xing, Weifeng Huang, Andy Tsun, Yingda Xu, Xiaolin Liu, Yi Luo. Discovery of an asymmetric IgG-like bispecific ADC targeting EGFR/HER3 [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 5083.

Abstract 2609: Vesicular LGALS3BP is a neuroblastoma biomarker and a therapeutic target for combination therapy with antibody-drug conjugate and checkpoint inhibitors

Abstract We have recently shown that targeting circulating LGALS3BP with a maytansinoid-based non-internalizing antibody-drug conjugate (ADC) resulted in tumor eradication of high-risk NMYC-amplified neuroblastoma patient-derived xenografts. LGALS3BP is a high molecular weight, hyperglycosylated and secreted protein which is enriched at the surface of cancer-derived extracellular vesicles (EVs). Here, using a neuroblastoma pseudometastatic preclinical model, we extended our previous work demonstrating that EVs-associated LGALS3BP strictly correlates with disease progression and dissemination. Moreover, to investigate whether LGALS3BP ADC, named 1959sss/DM4, possesses immune-modulating properties, we analyzed DM4 ability to induce immunogenic cell death (ICD). Interestingly, using NXS2 murine neuroblastoma cells, we found that DM4 induced a time-dependent surface expression of three different ICD marker, i.e. calreticulin, HSP70 and HSP90. As it was recently demonstrated that to limit immune surveillance NXS2 cells increase PD-L1 expression in response to IFNγ production in the tumor immune infiltrate, we evaluated potential synergism between LGALS3BP targeting ADC and an anti-PD1 immune check-point inhibitor. To this aim, we genetically manipulated NXS2 cells which resulted nearly negative for murine LGALS3BP expression. Therefore, using a lentivirus-based gene transduction system, we obtained NXS2 cells producing large amounts of vesicular human LGALS3BP. Of note, the vesicular LGALS3BP could be quantified by ELISA and imaged by confocal microscopy using 1959 antibody. Strikingly, while single agent treatment showed a limited antitumor activity in NXS2-LGALS3BP syngeneic model, the LGALS3BP ADC/anti-PD1 combination resulted in a marked inhibition of tumor growth, which was followed by a prolonged survival. In conclusion, our findings establish that vesicular LGALS3BP is a potential biomarker for liquid biopsy and reveals this protein as a suitable target for therapeutic strategy that combines 1959sss/DM4 ADC with immune checkpoint blockade for the treatment of LGALS3BP expressing neuroblastoma. Citation Format: Gianluca Sala, Emily Capone, Ilaria Cela, Giulio Lovato, Alessia Lamolinara, Manuela Iezzi, Cosmo Rossi, Vincenzo De Laurenzi, Rodolfo Ippoliti, Stefano Iacobelli. Vesicular LGALS3BP is a neuroblastoma biomarker and a therapeutic target for combination therapy with antibody-drug conjugate and checkpoint inhibitors [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 2609.

Phase 1 Study of the Tissue Factor–Targeting Antibody-Drug Conjugate XB002 in Patients with Advanced Solid Tumors (JEWEL-101): Design of Expansion Cohorts for Squamous Cell Carcinoma of the Head and Neck

Phase 1 Study of the Tissue Factor–Targeting Antibody-Drug Conjugate XB002 in Patients with Advanced Solid Tumors (JEWEL-101): Design of Expansion Cohorts for Squamous Cell Carcinoma of the Head and Neck

Delivery of a BET protein degrader via a CEACAM6-targeted antibody–drug conjugate inhibits tumour growth in pancreatic cancer models

Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis of all cancers. To improve PDAC therapy, we establish screening systems based on organoid and co-culture technologies and find a payload of antibody–drug conjugate (ADC), a bromodomain and extra-terminal (BET) protein degrader named EBET. We select CEACAM6/CD66c as an ADC target and developed an antibody, #84.7, with minimal reactivity to CEACAM6-expressing normal cells. EBET-conjugated #84.7 (84-EBET) has lethal effects on various PDAC organoids and bystander efficacy on CEACAM6-negative PDAC cells and cancer-associated fibroblasts. In mouse studies, a single injection of 84-EBET induces marked tumor regression in various PDAC-patient-derived xenografts, with a decrease in the inflammatory phenotype of stromal cells and without significant body weight loss. Combination with standard chemotherapy or PD-1 antibody induces more profound and sustained regression without toxicity enhancement. Our preclinical evidence demonstrates potential efficacy by delivering BET protein degrader to PDAC and its microenvironment via CEACAM6-targeted ADC.

Abstract B013: Folate receptor alpha (FRa) expression and correlation with other molecular alterations in high grade serous endometrial cancer (EC)

Abstract Background: Advanced and recurrent EC remains a therapeutic challenge with rising mortality rates and few options beyond first line platinum-based chemotherapy and immunotherapy. Mirvetuximab soravtansine (MIRV), an antibody drug conjugate (ADC) comprising a FRα-binding antibody, cleavable linker, and maytansinoid payload DM4, is FDA-approved for patients with FRa-high platinum resistant ovarian cancer (PROC). FRa is also expressed in EC and is associated with poor prognosis. Here, we evaluate FRa expression levels and associations with other molecular alterations, including in HER2, MYC and CCNE1, in patients with advanced/recurrent serous EC. Methods: Paraffin fixed tumor tissue from 110 patients who signed prescreening consent for a phase 2 study testing the combination of MIRV with pembrolizumab in recurrent/persistent serous EC (NCT03835819) were analyzed for FRα expression by IHC (Ventana, Inc). All patients had advanced or recurrent MSS serous EC and had received 1-3 prior lines of therapy. FRα positivity was defined as ≥50% of cells with ≥2+ membrane staining based on results from a phase 1b study of mirv and pembrolizumab in PROC (Matulonis U, SGO 2018 abstract 74). HER2/neu expression was assessed by independent pathology review at the treating institution. Tumor mutational burden (TMB), amplification of CCNE1, MYC and ERBB2 and other somatic mutations were determined in tumors with next generation sequencing (NGS). Results: 37 of 110 tumors were determined to be FRa positive (FRa+) with FRa ≥50% for an overall positivity rate of 33.63%. The median membrane positivity was 20.5% (IQR: 3-51.25). Within a cohort of 44 patients with available tumor NGS, the average TMB was 6.23 (SD: 3.34) and did not differ between FRα+ and -negative (FRα-) tumors at 5.74 and 6.45, respectively (p=0.73). Of 32 tumors with HER2 IHC performed, 5 (16%) were both FRα+ and HER2+ (2+ or 3+); 7 (22%) were FRα+ and HER2-, 5 (16%) were FRα- and HER2+, and 15 (47%) had negative expression for both. CCNE1, MYC and ERBB2 amplifications were present in 1 (9%), 0 and 3 (27%) of FRα+ tumors, and 6 (23%), (8) 31%, and 2 (8%) and of FRα- tumors, respectively. There was no association between expression of FRα and HER2 (Fisher exact test, p=0.44), nor with amplification of CCNE1 (p=0.65), MYC (p=0.08) and ERBB2 (p=0.14). The most common co-occurring somatic mutations were in PIK3CA, with similar frequency in FRα+ (55%) and FRα- (42%) tumors. Conclusions: An FRα positivity rate of 33.6% in this large cohort of serous EC tumors supports further clinical development of MIRV in this high-risk subtype of EC. Within a limited cohort subset, it does not appear that FRα expression correlates with TMB or HER2 expression, or with CCNE1, MYC or ERBB2 amplifications. This data highlights the importance of comprehensive testing of EC tumors for all relevant biomarkers that may guide selection of targeted therapies. Additional studies are needed to explore FRα expression in other molecular subsets of EC and to determine the longitudinal stability of ADC target expression. Citation Format: Rebecca L. Porter, Sandy Elias, Niya Xiong, Madeline Polak, Kayla Fahey, Nabihah Tayob, Courtney Qi, Carina Feeney, Swati Narayan, Jennifer Curtis, Susana Campos, Carolyn Krasner, Elizabeth Lee, Elizabeth Stover, Alexi A. Wright, Joyce F. Liu, Ursula A. Matulonis, Panagiotis Konstantinopoulos. Folate receptor alpha (FRa) expression and correlation with other molecular alterations in high grade serous endometrial cancer (EC) [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr B013.

65 Recent developments in antibody-drug conjugates (ADC) in the treatment of head & neck cancer

Chemotherapy, targeted therapy and immunotherapy represent standard of care treatment options in patients with head and neck squamous cell carcinoma (HNSCC). Despite this armamentarium, the prognosis of patients with recurrent and/or metastatic disease remains poor.Antibody drug conjugates (ADC) are a novel class of anticancer drugs that are composed by an antibody, a linker and a payload consisting of anticancer drug. Additional important features include the Drug Antibody Ratio (DAR) and the stability of the linker. The aim of ADCs is to deliver conjugated drugs selectively to cancer cells while sparing normal cells.First ADCs were approved for clinical use more than two decades ago, initially for the treatment of hematological malignancies followed by metastatic breast cancer.The most obvious target for ADCs in HNSCC is EGFR, but other targets were investigated as well. Results of clinical trials investigating the safety and efficacy of ADCs in HNSCC will be presented.

Combined inhibition of HER2 and VEGFR synergistically improves therapeutic efficacy via PI3K-AKT pathway in advanced ovarian cancer

BackgroundOvarian cancer (OC) is a prevalent malignancy in the female reproductive system, and developing effective targeted therapies for this disease remains challenging. The aim of this study was to use clinically-relevant OC models to evaluate the therapeutic effectiveness of RC48, an antibody-drug conjugate (ADC) targeting HER2, either alone or in combination with the VEGFR inhibitor Cediranib Maleate (CM), for the treatment of advanced OC.MethodsOC tumor specimens and cell lines were analyzed to determine HER2 and VEGFR expression by Western blot, immunocytochemistry and immunofluorescence. Moreover, the OC cell lines, cell-derived xenograft (CDX) and patient-derived xenograft (PDX) models were treated with RC48 and/or CM and then subjected to cell proliferation, viability, apoptosis, and tumor growth analyses to evaluate the feasibility of combination therapy for OC both in vitro and in vivo. Additionally, RNA-Seq was performed to investigate the critical mechanism underlying the combination therapy of RC48 and CM.ResultsOur results demonstrated that RC48 alone effectively targeted and inhibited the growth of HER2-positive OC tumors in both cell lines and PDX models. Furthermore, the combination of RC48 and CM synergistically induced tumor regression in human OC cell lines, as well as CDX and PDX models. Mechanistically, we observed that the combination treatment inhibited the growth of OC cells involved inducing apoptosis and suppressing cell motility. RNA-seq analysis provided further mechanistic insights and revealed that co-administration of RC48 and CM downregulated multiple cancer-related pathways, including the AKT/mTOR pathway, cell cycle, and cell proliferation. Notably, our data further confirmed that the PI3K-AKT pathway played a key role in the inhibition of proliferation triggered by combinational treatment of RC48 and CM in OC cells.ConclusionsThese findings provide a preclinical framework supporting the potential of dual targeting HER2 and VEGFR as a promising therapeutic strategy to improve outcomes in patients with OC.

Revisiting Treatment of Metastatic Urothelial Cancer: Where Do Cisplatin and Platinum Ineligibility Criteria Stand?

Cisplatin-based chemotherapy has been the standard of care in metastatic urothelial cancer (mUC) for more than two decades. However, many patients with comorbidities cannot receive cisplatin or its alternative, carboplatin. 'Cisplatin-ineligible' and 'platinum-ineligible' patients lacked effective therapy options. However, the recent combination of enfortumab vedotin (EV), an antibody-drug conjugate targeting Nectin-4, with pembrolizumab (P), an antibody targeting the programmed death-1 (PD-1) immune checkpoint, is changing the status quo of frontline mUC treatment, with potential synergy seen in the EV-103 and EV-302 clinical trials. First, we review the working definitions of 'cisplatin ineligibility' and 'platinum ineligibility' in mUC clinical trials and the standard of care in both categories. Then, we review select clinical trials for frontline treatment of cisplatin- and platinum-ineligible mUC patients on ClinicalTrials.gov. We classify the investigated drugs in these trials by their therapeutic strategies. Alongside chemotherapy combinations, the field is witnessing more immunotherapy combinations with fibroblast growth factor receptor (FGFR) inhibitors, bicycle toxin conjugates, bispecific antibodies, innovative targeted therapies, and many others. Most importantly, we rethink the value of classifying patients by cisplatin or platinum ineligibility in the frontline setting in the post-EVP era. Lastly, we discuss new priority goals to tailor predictive, monitoring, and prognostic biomarkers to these emergent therapies.

Expression of HER2 in high-grade urothelial carcinoma based on Chinese expert consensus and the clinical effects of disitamab vedotin-tislelizumab combination therapy in the treatment of advanced patients.

Background: A vast number of researchers have discovered high levels of human epidermal growth factor receptor-2 (HER2) expression in urothelial carcinoma (UC), but they do not use a uniform scoring system. Based on the 2021 edition of clinical pathological expert consensus on HER-2 testing in UC in China, we investigated the expression level and clinical significance of HER2 in high-grade UC. Furthermore, we looked at the prognosis of patients with locally advanced/metastatic UC after combining HER2 targeting antibody-drug conjugates (ADC) medication disitamab vedotin (DV) with programmed cell death protein 1 (PD-1) inhibitor tislelizumab. Patients and methods: From 2019 to 2022, we collected paraffin specimens of UC from the Department of Urology at the Provincial Hospital Affiliated to Shandong First Medical University. HER2 expression-related factors were investigated. Patients with advanced UC who have failed systemic chemotherapy at least once and had received immune checkpoint inhibitor (ICI) medication during second-line treatment were selected and treated with DV in combination with tislelizumab. We assessed the therapy's efficacy and safety. Results: 185 patients with high-grade UC were included in this investigation. 127 patients (68.7%) were HER2 positive (IHC 2+/3+) according to the 2021 Clinical pathological expert consensus on HER2 testing in UC in China. The clinical stage of UC differed statistically significantly between the HER2-and HER2+ groups (p = 0.019). Sixteen advanced UC patients were treated with DV and tislelizumab for a median of 14months. The disease control rate was 87.5%, while the objective response rate (ORR) was 62.5%. The ORR of HER2+ individuals was higher than that of HER2-individuals (70.0% vs. 50.0%). The median progression-free survival or overall survival was not reached. In this study, the incidence of treatment-related adverse events was 68.8% (11/16), with all of them being grade 1 or 2 adverse reactions. Conclusion: HER2 protein expressed at a high percentage in UC, and 68.7% patients expressed HER2 positive (IHC 2+/3+). HER2+ expression is positively correlated with higher clinical stage of UC. HER2 targeted ADC drug disitamab vedotin combining with PD-1 inhibitor tislelizumab has shown efficacy, safety and controllable adverse reactions in the treatment of advanced UC.