Targeting HER2 Research Articles

Rhodanine–Piperazine Hybrids as Potential VEGFR, EGFR, and HER2 Targeting Anti-Breast Cancer Agents

Breast cancer is one of the most common malignancies affecting women worldwide, with a significant need for novel therapeutic agents to target specific molecular pathways involved in tumor progression. In this study, a series of rhodanine–piperazine hybrids were designed, synthesized, and evaluated for their anticancer activity, targeting key tyrosine kinases such as VEGFR, EGFR, and HER2. Biological screening against breast cancer cell lines (MCF-7, MDA-MB-231, T47D, and MDA-MB-468) revealed 3 of the 13 tested compounds as the most potent, with 5-({4-[bis(4-fluorophenyl)methyl]piperazin-1-yl}methylidene)-2-thioxo-1,3-thiazolidin-4-one (12) showing the strongest activity, particularly against the MCF-7 and MDA-MB-468 cell lines. Molecular docking studies indicated favorable binding interactions of compound 12 and its 3-phenyl-2-thioxo-1,3-thiazolidin-4-one analogue (15) with HER2, VEGFR, and EGFR, and molecular dynamics simulations further confirmed their stable binding to HER2. These findings highlight the potential of rhodanine–piperazine hybrids as promising leads for developing new anticancer agents targeting breast cancer, particularly HER2-positive subtypes. Further structural optimization could enhance their efficacy and therapeutic profile.

Abstract B007: Identification of Asporin as a HER3 ligand exposes a therapeutic vulnerability in metastatic prostate cancer

Abstract Background: Rates of prostate cancer incidence and advanced-stage diagnoses are increasing. Despite curative-intent therapies, nearly all patients with advanced disease progress to metastatic castration-resistant prostate cancer (mCRPC), a lethal form of the disease. There is an urgent unmet need to understand the mechanisms driving prostate cancer progression and identify alternative therapies for patients with mCRPC. It is well-established that cancer-associated fibroblasts (CAF) in the tumor microenvironment secrete factors that enable cancer cells to establish metastases. Asporin (ASPN) is an extracellular protein secreted by a subset of CAF and is associated with worse oncologic outcomes, yet the mechanisms remain poorly understood. In this study, we sought to identify the molecular interactions between the CAF-secreted ASPN and metastatic prostate cancer cells. Methods: ASPN-induced HER2/HER3 activation and downstream signaling was identified by RNA-sequencing and then confirmed by immunoblotting in multiple human metastatic prostate cancer cell lines. Binding interactions were assessed computationally by AlphaFOld2 with Rosetta refinement and substantiated by co-immunoprecipitation assays. CRISPR-cas9 targeting of HER2 and HER3 and therapeutic inhibition of HER2 with Tucatinib were used to determine the role of HER2/HER3 in ASPN-induced signaling and migration. The efficacy of Tucatinib and antibody-drug conjugates (ADC) targeting HER2 (Trastuzumab-deruxtecan) and HER3 (Patritumab-deruxtecan) were assessed in multiple metastatic prostate cancer cell lines in vitro. Trastuzumab-deruxtecan was assessed in PC3 xenografts in vivo. Prostate cancer metastases from 33 patients were assessed by IHC for HER2 and HER3 and by RNAscope for ASPN. Results: We report that ASPN is a novel ligand of HER3 and induces HER3 heterodimerization with its preferred dimerization partner, HER2. ASPN activates established ErbB-associated pathways including Phosphoinositide 3-kinase (PI3K), Mitogen-activated protein kinase (MAPK), and calcium signaling, in multiple metastatic prostate cancer cell lines to promote cell migration. Genetic and molecular inhibition of HER2/HER3 mitigates ASPN-induced signaling and cell migration, suggesting these receptors are required for paracrine activation by ASPN. Importantly, small molecule and ADC therapies targeting HER2/HER3 significantly diminished prostate cancer cell growth in vitro, with enzalutamide-resistant cells showing increased sensitivity. Trastuzumab-deruxtecan nearly resolved tumors in an in vivo xenograft model. Lastly, ASPN+ CAF in the TME of HER2/HER3-expressing metastatic prostate cancer is frequently observed in patient samples, supporting the clinical relevance of these findings. Conclusions: Collectively, these findings indicate ASPN functions as a HER3 ligand to induce cellular migration, and inhibition with anti-HER2/HER3 therapies highlights potential clinical utility for patients with HER2-expressing metastatic prostate cancer. Citation Format: Amanda B. Hesterberg, Hong Yuen Wong, Jorgen Jackson, Monika Antunovic, Brenda L. Rios, Evan Watkins, Riley E. Bergman, Brad A. Davidson, Sarah E. Ginther, Diana Graves, Elliott F. Nahmias, Jared A. Googel, Lillian B. Martin, Violeta Sanchez, Paula Gonzalez Ericsson, Quanhu Sheng, Benjamin P. Brown, Jens Meiler, Ben H. Park, Kerry R. Schaffer, Jennifer B. Gordetsky, Paula J. Hurley. Identification of Asporin as a HER3 ligand exposes a therapeutic vulnerability in metastatic prostate cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B007.

Abstract C005: Tumor vaccines and oncolytic virotherapy: systemic immunity vs. tumor microenvironment

Abstract Tumor vaccines, particularly the innovative mRNA variants, hold immense promise in cancer immunotherapy. Despite their potential, these vaccines encounter formidable challenges in surmounting immune tolerance, the immune-suppressive tumor microenvironment (TME) and more importantly, the resistance developed in cancer cells that are antigen negative. Concurrently, oncolytic virotherapy (OV), a distinct facet of tumor vaccination, significantly alters the TME and releases tumor antigens via lysis to generate a broader spectrum of tumor antigens. This unique property positions OV to induce anti-tumor immunity, as evidenced by prolonged overall survival and abscopal tumor suppression. Recognizing the complementary strengths of mRNA tumor vaccines and OV, we propose a combined approach to address the limitations inherent in each modality. Our study tested this hypothesis by combining a mRNA vaccine targeting HER2 with oncolytic viruses, utilizing a prime-boost strategy on a HER2-expressing CT26 mouse tumor model. Notably, while the mRNA vaccine alone induced specific anti-HER2 systemic immunity, the combination demonstrated a potent immune response against both anti-HER2 and anti-CT26, leading to durable tumor eradication. Our findings highlight that peripheral vaccination has the potential to elicit an immune response in non-immune suppressive environments. However, combining it with virotherapy not only amplifies specific immunity but also induces a broader immune response against a spectrum of tumor antigens. This synergistic combination represents a promising avenue for advancing cancer immunotherapy, offering the potential for improved treatment outcomes and broader applicability of tumor vaccines across diverse cancer types. Citation Format: William Jia. Tumor vaccines and oncolytic virotherapy: systemic immunity vs. tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C005.

Targeted treatment of gastric cancer and its pathogenic mechanism

Abstract. Gastric cancer (GC) is a malignant tumor with high morbidity and mortality in our country. The traditional treatment methods include operation, radiotherapy and chemotherapy. At present, it cannot be cured by traditional treatment. Targeted therapy is a treatment method for GC targeting specific targets. Currently, the main therapeutic targets developed include HER2, VEGF and EGFR. It has the advantages of less side effects and good efficacy, but it still has the defect of not fully covering the patient population. This paper mainly introduces targeted therapy of GC, an emerging treatment method, and obtains relevant information about the pathogenic mechanism and main drugs of its main targets HER2, VEGF and EGFR. By summarizing the above information, this paper hopes to provide reference for the future research of targeted therapy of GC and make contributions to the development of more new targets of GC in the future.

Programmable Circular Multivalent Nanobody‐Targeting Chimeras (mNbTACs) for Multireceptor‐Mediated Protein Degradation and Targeted Drug Delivery

AbstractMultispecific therapeutics hold significant promise in drug delivery, protein degradation, and cell recruitment to address clinical issues of tumor heterogeneity, resistance, and immune evasion. However, their modular engineering remains challenging. We developed a targeted degradation platform, termed multivalent nanobody‐targeting chimeras (mNbTACs), by encoding diverse nanobody codons on a circular template using DNA printing technology. The homo‐ or hetero‐ mNbTACs specifically recognized membrane targets in a multivalent manner and simultaneously recruited scavenger receptors to favor clathrin‐/caveolae‐dependent endocytosis and lysosomal degradation of multiple proteins with high efficiency and selectivity. We demonstrated that a bispecific doxorubicin‐loaded mNbTAC, named Doxo‐mvNbsPPH, passively accumulated at tumor sites, specifically interacted with PD−L1 and HER2 targets, and was rapidly transported into lysosome, inducing potent immunogenic cell death and alleviating immune checkpoint evasion. The synergistic boosting of innate and adaptive immunity promoted the infiltration and proliferation of CD8+ T cells in tumor microenvironment (an 11‐fold increase) with high toxicity and low exhaustion, eventually enhancing antitumor efficacy. Our mNbTAC platform provides multispecific therapeutics with variable valences and programmed species, whereas it induces targeted protein degradation through multireceptor‐mediated endocytosis and lysosomal degradation without the need for lysosome‐targeting receptors, representing a general and modular tool to harness extracellular proteome for disease treatment.

CTIM-04. MODULATION OF THE INTRATUMORAL IMMUNE MICROENVIRONMENT BY LOCAL THERAPY WITH NATURAL KILLER CELLS ENGINEERED WITH A HER2-TARGETED CHIMERIC ANTIGEN RECEPTOR IN COMBINATION WITH SYSTEMIC ANTI-PD-1 CHECKPOINT INHIBITION IN PATIENTS WITH RECURRENT GLIOBLASTOMA

Abstract Glioblastoma (GB) is characterized by a marked immunosuppressive tumor microenvironment. In the multicenter CAR2BRAIN phase I first-in-human clinical trial, we investigated the modulation of the tumor microenvironment by repetitive local injection of clonal chimeric antigen receptor (CAR)-NK cells (NK-92/5.28.z) targeting HER2 alone and in combination with systemic anti-PD-1 checkpoint inhibitor therapy in patients with recurrent HER2-positive GB. 6 patients were treated with repetitive doses of CAR-NK cells as monotherapy and 12 patients received a combination therapy with the anti-PD-1 checkpoint inhibitor ezabenlimab. In three of those, we were able to implement a biopsy-treat-resect-treat strategy. After initial biopsy, combination treatment was initiated before planned tumor resection, enabling analysis of the transformation of the tumor immune microenvironment by highplex multispectral fluorescent analyses and cytokine quantification. None of the patients developed a cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. Profound alterations of the immune cell distribution in the cerebrospinal fluid (CSF) and in the tumor were observed. In CSF sampled from the resection cavity, combination immunotherapy induced a local immune response with elevated pro-inflammatory cytokines and cell counts. In post-treatment tissue samples, we observed an increase of CD4+ and CD8+ T cells, and a decrease of regulatory CD4+FoxP3+ T cells. The three patients treated following the biopsy-treat-resect-treat strategy achieved a median progression-free survival (PFS) of 24 weeks, compared to 10 weeks for patients with upfront resection. Local immunotherapy with HER2-targeted CAR-NK cells is feasible and safe both as monotherapy and in combination with the systemic checkpoint inhibitor ezabenlimab and induces local immune reactions in CSF and tumor tissue. Given the signal for possible clinical benefit provided by the increase in PFS in the patients of the biopsy-treat-resect-treat cohort, further trials are warranted.

DDEL-14. NOVEL BLOOD BRAIN BARRIER PENETRATING BI-SPECIFIC ANTIBODY THERAPY FOR BREAST CANCER BRAIN METASTASIS

Abstract Breast cancer is the second leading cause for brain metastasis after lung cancer. While Her2 +ve tumors respond to her2 targeted antibody therapy, these antibodies are unable to cross the blood brain tumor barrier to effectively target metastases hidden in the ‘CNS sanctuary’. To overcome this hurdle, we have modified Her2 targeting Herceptin to create a CNS penetrating antibody that is transported in a unidirectional fashion into brain tumors. The modified BBB penetrating Herceptin is processed by the tumor specific microenvironment after crossing the BBB, such that the modified antibody is then trapped in the tumor ECM. This has the potential to increase tumor retention and reduce systemic toxicity. The BBB penetrant anti Her2 antibody (Herceptin) binds to Her2 on breast cancer cells and suppresses activation of Her2 signaling in vitro. Western blot analysis shows reduction of Her2 phosphorylation and down stream signaling with both unmodified and BBB modified Herceptin. This permits recruitment and retention of the antibody into the CNS tumors. Using fluorescence imaging and IHC of intracranial tumors we have validated that the BBB modified Herceptin is localized into intracranial tumors. We are currently evaluating the safety and therapeutic benefit of this approach in mice bearing intracranial tumors.

BIOM-34. INTRACRANIAL MANAGEMENT OF HER-2 OVEREXPRESSION BREAST CANCER WITH EXTENSIVE VOLUME OR SYMPTOMATIC BRAIN METASTASES

Abstract BACKGROUND HER-2 overexpression in breast cancer often leads to brain metastases, necessitating effective intracranial control strategies. This study aimed to evaluate the correlation between intracranial disease volume, symptomatic presentation, and treatment outcomes in HER-2 overexpressing breast cancer patients with brain metastases. METHODS A retrospective analysis was conducted on cases of HER-2 overexpressing breast cancer patients with brain metastases. Clinical records were reviewed to extract patient demographics, treatment modalities, and intracranial disease characteristics. Intracranial tumor burden was quantified at diagnosis and post-initial treatment. High intracranial tumor burden was defined as either total metastatic volume >15 cc, or the largest lesion >3 cm. Responses were assessed using established criteria. The correlation between intracranial disease parameters and intracranial progression-free survival (PFS) and overall survival (OS) was determined. RESULTS The study comprised 65 patients with HER-2 overexpression breast cancer and brain metastases. Symptomatic presentation was observed in 69.2% of patients at the diagnosis of brain metastases. Treatment with HER-2 target therapy alone or in combination with other modalities resulted in substantial intracranial responses, with 81.5% achieving at least a partial response at 3 months from therapy initiation. Median intracranial PFS and OS for patients with high intracranial burden were 9 and 22 months, respectively. Patients with high intracranial burden and symptomatic presentation at diagnosis demonstrated worse PFS and OS to those with lower burden and absence of symptoms (p < 0.05 for each). CONCLUSION Intracranial control in HER-2 overexpressing breast cancer patients with large volume or symptomatic brain metastases appears promising with combination with HER-2 targeted therapy and radiotherapy. Despite the varying intracranial disease burdens and symptomatic presentations, the use of HER-2 targeted therapy combined with radiotherapy demonstrates favorable intracranial responses, highlighting their potential in managing such cases.

ERBB2/ ERBB3-mutated S100/ SOX10-positive unclassified high-grade uterine sarcoma: first detailed description of a novel entity.

With the increasing use of innovative next generation sequencing (NGS) platforms in routine diagnostic and research settings, the genetic landscape of uterine sarcomas has been dynamically evolving during the last two decades. Notably, the majority of recently recognized genotypes in uterine sarcomas represent gene fusions, while recurrent oncogene mutations of diagnostic and/ or therapeutic value have been rare. Recently, a distinctive aggressive uterine sarcoma expressing S100 and SOX10, but otherwise lacking diagnostic morphological, immunophenotypic and molecular features of other uterine malignancies has been presented in a scientific abstract form (USCAP, 2023), but detailed description and delineation of the entity is still missing. We herein describe two high-grade unclassified uterine sarcomas characterized by spindle to round cell morphology and diffuse expression of S100 and SOX10, originating in the uterine body and cervix of 53- and 45-year-old women and carrying an ERBB3 (p.Glu928Gly) and an ERBB2 (p.Val777Leu) mutation, respectively. Both tumors harbored in addition genomic HER2 amplification, ATRX mutation and CDKN2A deletion. Methylation studies revealed a methylome most similar to MPNST-like tumors, but distinct from melanoma, MPNST, clear cell sarcoma, and endometrial stromal sarcoma. Case 1 died of progressive peritoneal metastases after multiple trials of chemotherapy 47months after diagnosis. Case 2 is a recent case who presented with a cervical mass, which was biopsied. This study defines a novel heretofore unrecognized aggressive uterine sarcoma with unique phenotypic and genotypic features. Given the potential value of targeting HER2, recognizing this tumor type is mandatory for appropriate therapeutic strategies and for better future delineation of the entity.

HER2 amplification and PD-L1 expression in invasive stratified mucin-producing carcinoma of the cervix: a clinicopathological analysis of eighteen cases

Objective: To investigate the clinicopathological features, prognosis and the expression of HER2 and PD-L1 in invasive stratified mucin-producing carcinoma of the cervix (ISMC). Methods: The clinicopathological data of 18 ISMC cases with radical resection of the cervix diagnosed in the Daping Hospital, Army Medical University from January 2018 to December 2023 were collected and retrospectively analyzed. PD-L1 and HER2 immunohistochemical staining and HER2 FISH were conducted. Results: The patient ages ranged from 31 to 72 years, with an average of 45 years. Approximately 8% of cervical adenocarcinoma cases in our hospital during the same period. Eleven cases were pure ISMC, and 7 cases were mixed-type ISMC, with the component of squamous cell carcinoma or usual-type adenocarcinoma. One case showed concurrent small cell neuroendocrine carcinoma (SCNEC). Three cases were diagnosed through biopsy (3/18). Five cases were of Silva pattern B and 13 cases of Silva pattern C. Three cases showed regional lymph node metastasis. Thirteen patients were disease-free at the end of the follow-up, while the ISMC patient with concurrent SCNEC developed distant metastasis. Fifteen cases (15/18) had PD-L1 expression with CPS≥1, and 7 cases (7/18) had PD-L1 TPS≥1%. One case of HER2 3+ and one case of HER2 2+ were both positive for FISH amplification; two cases HER2 1+, 14 cases HER2 0. Conclusions: Cervical ISMC is rare, has a wide spectrum of morphology, and can coexist with other types of cervical cancer. PD-L1 is positive in most of the ISMC cases, while HER2 is amplified or lowly expressed in a small portion of them. Thus, it is possible to treat ISMC patients with therapies targeting PD-L1 and therapy targeting HER2.

Cardiac toxicity of HER-2 targeting antibody-drug conjugates: overview and clinical implications.

Antibody-drug conjugates (ADCs) have recently emerged as a promising therapeutic option that combine the specificity of monoclonal antibodies and the cytotoxic effect of chemotherapy. With numerous ADCs approved and on the market, a particular concern of ADCs that target HER-2 has been their cardiac side effects, in view of the crucial role of HER-2 in cardiac development and physiology. While rarely toxic and generally safe, numerous publications have outlined the consistent association of trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd) with the development of cardiac toxicity. Despite not being clinically relevant in most cases, cardiac baseline evaluation, monitoring and early detection of cardiac adverse events remain pivotal with HER-2 targeting ADCs. This review aims to summarize and better characterize the complete cardiac toxicity profile of HER-2 ADCs, with the goal of improving clinical understanding of this adverse event, leading to better recognition, monitoring and management.

Dual HER2 inhibition: Is two better than one?

Li etal. present data from a randomized frontline phase II trial in HER2+ gastroesophageal cancers exploring dual targeting of HER2 with HLX22 (a novel HER2-specific antibody) with HLX02 (a trastuzumab biosimilar) and capecitabine/oxaliplatin chemotherapy. While the objective response and progression-free survival are encouraging, the future development of the combination in a crowded HER2 space remains unclear.

Phase II Trial of HER-Vaxx, a B-cell Peptide-Based Vaccine, in HER2-Overexpressing Advanced Gastric Cancer Patients Under Platinum-Based Chemotherapy (HERIZON).

A multicenter, randomized, open-label, phase II study (HERIZON; NCT02795988) was conducted to evaluate the clinical and immunologic efficacy of HER-Vaxx (IMU-131), a B-cell, peptide-based vaccine targeting HER2 overexpressed in 6% to 30% of gastroesophageal adenocarcinomas (GEA). Patients (n = 36) with GEA were treated with standard-of-care chemotherapy (n = 17) or HER-Vaxx plus chemotherapy (n = 19), using the recommended phase 2 dose for the vaccine. Overall survival (OS; primary endpoint), safety, progression-free survival (PFS), clinical response (secondary endpoints), and vaccine-induced HER2-specific antibody levels in serum and correlation with tumor response rates (exploratory endpoints) were investigated. A 40% OS benefit [HR, 0.60; median OS, 13.9 months; 80% confidence interval (CI), 7.52-14.32] for patients treated with HER-Vaxx plus chemotherapy compared with OS of 8.31 months (80% CI, 6.01-9.59) in patients that received chemotherapy alone. A 20% PFS difference was obtained for the vaccination arm (HR, 0.80; 80% CI, 0.47, 1.38). No additional toxicity due to HER-Vaxx was observed. The vaccine-induced high levels of HER2-specific total IgG and IgG1 antibodies (P < 0.001 vs. controls) that significantly correlated with tumor reduction (IgG, P = 0.001; IgG1, P = 0.016), had a significant capacity in inhibiting phosphorylation of the intracellular HER2-signaling pathways, mediated antibody-dependent cellular cytotoxicity, and decreased immunosuppressive FOXP3+ regulatory T cells. HER-Vaxx plus standard chemotherapy exhibits an excellent safety profile and improves OS. Furthermore, vaccine-induced immune response was significantly associated with reduced tumor size compared with standard-of-care chemotherapy. The presented vaccination approach may substitute for treatment with trastuzumab, upon unavailability or toxicity, based on further evidence of equivalent treatment efficacy.

437TiP An open-label, multicenter, phase II study to evaluate the safety and efficacy of BB-1701, a novel antibody drug conjugate (ADC) targeting HER2, in previously treated patients (pts) with HER2+ or HER2-low unresectable or metastatic (M) breast cancer (BC)

437TiP An open-label, multicenter, phase II study to evaluate the safety and efficacy of BB-1701, a novel antibody drug conjugate (ADC) targeting HER2, in previously treated patients (pts) with HER2+ or HER2-low unresectable or metastatic (M) breast cancer (BC)

Amiloride Sensitizes Prostate Cancer Cells to the Reversible Tyrosine Kinase Inhibitor Lapatinib by Modulating ERBB3 Subcellular Localization.

Neoadjuvant therapy (NAT) has been studied in clinically localized prostate cancer (PCa) to improve the outcomes from radical prostatectomy (RP) by 'debulking' of high-risk PCa; however, using androgen deprivation at this point risks castration resistant PCa (CRPC) clonal proliferation with potentially profound side effects such as fatigue, loss of libido, hot flashes, loss of muscle mass, and weight gain. Our goal is to identify alternative NAT that reduce hormone sensitive PCa (HSPC) without affecting androgen receptor (AR) transcriptional activity. PCa is associated with increased expression and activation of the epidermal growth factor receptor (EGFR) family, including HER2 and ErbB3. Dimerization between these receptors is required for activation of downstream targets involved in tumor progression. The FDA-approved HER2 inhibitor lapatinib has been tested in PCa but was ineffective due to continued activation of ErbB3. We now demonstrate that this is due to ErbB3 being localized to the nucleus in HSPC and thus protected from lapatinib which affect membrane localized HER2/ErbB3 dimers. Here, we show that the well-established, well-tolerated diuretic amiloride hydrochloride dose dependently prevented ErbB3 nuclear localization via formation of plasma membrane localized HER2/ErbB3 dimers. This in turn allowed lapatinib inactivation of these dimers via inhibition of its target HER2, which dephosphorylated downstream survival and proliferation regulators AKT and ERK1/2. Amiloride combined with lapatinib significantly increased apoptosis but did not affect AR transcriptional activity. Thus, our data indicate that a combination of amiloride and lapatinib could target HSPC tumors without problems associated with androgen deprivation therapy in localized PCa.

A Non-Canonical p75HER2 Signaling Pathway Underlying Trastuzumab Action and Resistance in Breast Cancer.

Overexpression of HER2 occurs in 25% of breast cancer. Targeting HER2 has proven to be an effective therapeutic strategy for HER2-positive breast cancer. While trastuzumab is the most commonly used HER2 targeting agent, which has significantly improved outcomes, the overall response rate is low. To develop novel therapies to boost trastuzumab efficacy, it is critical to identify the mechanisms underlying trastuzumab action and resistance. We recently showed that the inhibition of breast cancer cell growth by trastuzumab is not through the inhibition of HER2 canonical signaling. Here we report the identification of a novel non-canonical HER2 signaling pathway and its interference by trastuzumab. We showed that HER2 signaled through a non-canonical pathway, regulated intramembrane proteolysis (RIP). In this pathway, HER2 is first cleaved by metalloprotease ADAM10 to produce an extracellular domain (ECD) that is released and the p95HER2 that contains the transmembrane domain (TM) and intracellular domain (ICD). p95HER2, if further cleaved by an intramembrane protease, γ-secretase, produced a soluble ICD p75HER2 with nuclear localization signal (NLS). p75HER2 is phosphorylated and translocated to the nucleus. Nuclear p75HER2 promotes cell proliferation. Trastuzumab targets this non-canonical HER2 pathway via inhibition of the proteolytic cleavage of HER2 by both ADAM10 and γ-secretase. However, p75HER2 pathway also confers resistance to trastuzumab once aberrantly activated. Combination of trastuzumab with ADAM10 and γ-secretase inhibitors completely blocks p75HER2 production in both BT474 and SKBR3 cells. We concluded that HER2 signals through the RIP signaling pathway that promotes cell proliferation and is targeted by trastuzumab. The aberrant HER2 RIP signaling confers resistance to trastuzumab that could be overcome by the application of inhibitors to ADAM10 and γ-secretase.

A novel HER2 targeting nanoagent self-assembled from affibody-epothilone B conjugate for cancer therapy

Epothilone B (Epo B), a promising antitumor compound effective against various types of cancer cells in vitro. However, its poor selectivity for tumor cells and inadequate therapeutic windows significantly limit its potential clinical application. Affibody is a class of non-immunoglobulin affinity proteins with precise targeting capability to overexpressed molecular receptors on cancer cells, has been intensively investigated due to its exceptional affinity properties. In this study, we present a targeted nanoagent self-assembled from the precursor of an affibody conjugated with Epo B via a linker containing the thioketal (tk) group that is sensitive to reactive oxygen species (ROS). The core-shell structure of the ZHER2:342-Epo B Affibody-Drug Conjugate Nanoagent (Z-E ADCN), with the cytotoxin Epo B encapsulated within the ZHER2:342 affibody corona, leads to significantly reduced side effects on normal organs. Moreover, the abundant presence of ZHER2:342 on the surface effectively enhances the targeting capacity and tumor accumulation of the drug. Z-E ADCN can be internalized by cancer cells via HER2 receptor-mediated endocytosis followed by Epo B release in response to high levels of ROS, resulting in excellent anticancer efficacy in HER2-positive tumor models.

Dual-Targeting of the HER2 Cancer Receptor with an Antibody-Directed Enzyme and a Nanobody-Guided MMAE Prodrug Scaffold.

Antibody-enzyme conjugates have shown potential as tissue-specific prodrug activators by antibody-directed enzyme prodrug therapy (ADEPT), but the approach met challenges clinically due to systemic drug release. Here, we report a novel dual-targeting ADEPT system (DuADEPT) which is based on active cancer receptor targeting of both a trastuzumab-sialidase conjugate (Tz-Sia) and a highly potent sialidase-activated monomethyl auristatin E (MMAE) prodrug scaffold. The scaffold is based on a four-way junction of the artificial nucleic acid analog acyclic (L)-threoninol nucleic acid ((L)-aTNA) which at the ends of its four arms carries one nanobody targeting HER2 and three copies of the prodrug. Dual-targeting of the constructs to two proximal epitopes of HER2 was shown by flow cytometry, and a dual-targeted enzymatic drug release assay revealed cytotoxicity upon prodrug activation specifically for HER2-positive cancer cells. The specific delivery and activation of prodrugs in this way could potentially be used to decrease systemic side effects and increase drug efficacy, and utilization of Tz-Sia provides an opportunity to combine the local chemotherapeutic effect of the DuADEPT with an anticancer immune response.

New Treatments Target HER2 in Gastric Cancers

New Treatments Target HER2 in Gastric Cancers

96 A novel therapy based on SBRT targeting HER-2 expression advanced solid tumors (PRaG 3.0 Regimen)

96 A novel therapy based on SBRT targeting HER-2 expression advanced solid tumors (PRaG 3.0 Regimen)