EV20/NMS-P945, a Novel Thienoindole Based Antibody-Drug Conjugate Targeting HER-3 for Solid Tumors

Identification of CD66c as a potential target in gastroesophageal junction cancer for antibody-drug conjugate development

BACKGROUND

Gastroesophageal junction (GEJ) cancer exhibits unique biological characteristics and currently lacks specific targeted therapies. Given the clinical efficacy of antibody-drug conjugates (ADCs) in solid tumor treatment, we aimed to identify a novel ADC target and suitable payload for GEJ-targeted therapy.

METHODS

In this study, we conducted bioinformatic analyses of multi-omics data, including transcriptomics, proteomics, and phosphoproteomics, to identify CD66c as a promising ADC target for GEJ cancer. We then engineered a CD66c-directed antibody-drug conjugate (CD66c-DXd) incorporating a GGFG linker. The preclinical efficacy of CD66c-DXd was determined in multi GEJ xenograft models.

RESULTS

Proteomic analyses of 103 cases of GEJ cancer revealed that CD66c expression was significantly higher in tumoral tissues compared to normal tissues. Proteomic and phosphoproteomic analyses identified deruxtecan (DXd) as a potentially potent payload for ADCs targeting GEJ cancer. Furthermore, high CD66c expression in GEJ was associated with a significantly lower proportion of plasma cells. The drug-to-antibody ratio (DAR) of CD66c-DXd was determined to be 3.6. CD66c-DXd effectively and selectively ablated multiple human GEJ cell lines (OE-19, OE33 and SK-GT-4) without affecting non-malignant cells (GES-1) in vitro. Eventually, CD66c-DXd mediated potent and durable tumor regression in vivo with excellent safety profiles.

CONCLUSIONS

This preclinical study provides a strong rationale for the further development of CD66c-DXd as promising therapeutic candidates to treat advanced GEJ cancer. Additionally, the study demonstrates the robustness of the multi-omics data in identifying novel potential ADC targets and payloads.

Navigating the future of gastric cancer treatment: a review on the impact of antibody-drug conjugates

Gastric cancer, marked by its high incidence and poor prognosis, demands the urgent development of novel and effective treatment strategies, especially for patients ineligible for surgery or those who have had limited success with chemotherapy, radiotherapy and targeted therapies. Recently, antibody-drug conjugates (ADCs) have become a key area of investigation due to their high specificity and potent antitumor effects. These therapies combine monoclonal antibodies, designed to bind to tumor-specific antigens, with cytotoxic agents that selectively target and destroy malignant cells. ADCs have generated significant interest in clinical trials as a promising approach to improve both treatment efficacy and patient outcomes in gastric cancer. However, their clinical application is not without challenges and limitations that must be addressed. This review discusses the recent progress in the use of ADCs for gastric cancer treatment.

HER3: Updates and current biology function, targeted therapy and pathologic detecting methods

Being a member of the EGFR tyrosine kinase family, HER3 has been shown to be overexpressed in a number of cancers, including breast cancer (BC). The kinase activity of HER3 is extremely low, and it forms heterodimers with partners, HER2 in particular, that promote biological processes like cell migration, survival, and proliferation by activating downstream carcinogenic signaling pathways. The overexpression of HER3 is also directly linked to tumor invasion, metastasis, and a poor prognosis. Despite the relatively low expression of HER3 compared to EGFR and HER2, a lot of targeted drugs are making their way into clinical trials and seem to have a bright further. This review aims to summarize the relationship between HER3 overexpression, mutations, and carcinogenicity and drug resistance, starting from the unique structure and kinase activity of HER3. Simultaneously, numerous approaches to HER3 targeted therapy are enumerated, and the clinical detection methods for HER3 that are commonly employed in pathology are sorted and contrasted to offer physicians a range of options. We think that a better knowledge of the mechanisms underlying HER3 in tumors and the advancement of targeted HER3 therapy will contribute to an improved prognosis for cancer patients and an increase in the efficacy of anticancer therapies.

EV20/Omomyc: A novel dual MYC/HER3 targeting immunoconjugate

MYC is one of the most important therapeutic targets in human cancer. Many attempts have been made to develop small molecules that could be used to curb its activity in patients, but most failed to identify a suitable direct inhibitor. After years of preclinical characterization, a tissue-penetrating peptide MYC inhibitor, called Omomyc, has been recently successfully used in a Phase I dose escalation study in late-stage, all-comers solid tumour patients. The study showed drug safety and positive signs of clinical activity, prompting the beginning of a new Phase Ib combination study currently ongoing in metastatic pancreatic adenocarcinoma patients. In this manuscript, we have explored the possibility to improve Omomyc targeting to specific cancer subtypes by linking it to a therapeutic antibody. The new immunoconjugate, called EV20/Omomyc, was developed by linking a humanised anti-HER3 antibody, named EV20, to Omomyc using a bifunctional linker. EV20/Omomyc shows antigen-dependent penetrating activity and therapeutic efficacy in a metastatic model of neuroblastoma. This study suggests that directing Omomyc into specific cell types using antibodies recognising tumour antigens could improve its therapeutic activity in specific indications, like in the paediatric setting.

Antibody-drug conjugates in gastric cancer: from molecular landscape to clinical strategies

Antibody-drug conjugates (ADCs) represent a crucial component of targeted therapies in gastric cancer, potentially altering traditional treatment paradigms. Many ADCs have entered rigorous clinical trials based on biological theories and preclinical experiments. Modality trials have also been conducted in combination with monoclonal antibody therapies, chemotherapies, immunotherapies, and other treatments to enhance the efficacy of drug coordination effects. However, ADCs exhibit limitations in treating gastric cancer, including resistance triggered by their structure or other factors. Ongoing intensive researches and preclinical experiments are yielding improvements, while enhancements in drug development processes and concomitant diagnostics during the therapeutic period actively boost ADC efficacy. The optimal treatment strategy for gastric cancer patients is continually evolving. This review summarizes the clinical progress of ADCs in treating gastric cancer, analyzes the mechanisms of ADC combination therapies, discusses resistance patterns, and offers a promising outlook for future applications in ADC drug development and companion diagnostics.

Antibody-drug conjugates for hepato-pancreato-biliary malignancies: "Magic bullets" to the rescue?

Hepato-Pancreato-Biliary (HPB) malignancies constitute a highly aggressive group of cancers that have a dismal prognosis. Patients not amenable to curative intent surgical resection are managed with systemic chemotherapy which, however, confers little survival benefit. Antibody-Drug Conjugates (ADCs) are tripartite compounds that merge the intricate selectivity and specificity of monoclonal antibodies with the cytodestructive potency of attached supertoxic payloads. In view of the unmet need for drugs that will enhance the survival rates of HPB cancer patients, the assessment of ADCs for treating HPB malignancies has become the focus of extensive clinical and preclinical investigation, showing encouraging preliminary results. In the current review, we offer a comprehensive overview of the growing body of evidence on ADC approaches tested for HPB malignancies. Starting from a concise discussion of the functional principles of ADCs, we summarize here all available data from preclinical and clinical studies evaluating ADCs in HPB cancers.

HER3-targeted therapy: the mechanism of drug resistance and the development of anticancer drugs

Human epidermal growth factor receptor 3 (HER3), which is part of the HER family, is aberrantly expressed in various human cancers. Since HER3 only has weak tyrosine kinase activity, when HER3 ligand neuregulin 1 (NRG1) or neuregulin 2 (NRG2) appears, activated HER3 contributes to cancer development and drug resistance by forming heterodimers with other receptors, mainly including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Inhibition of HER3 and its downstream signaling, including PI3K/AKT, MEK/MAPK, JAK/STAT, and Src kinase, is believed to be necessary to conquer drug resistance and improve treatment efficiency. Until now, despite multiple anti-HER3 antibodies undergoing preclinical and clinical studies, none of the HER3-targeted therapies are licensed for utilization in clinical cancer treatment because of their safety and efficacy. Therefore, the development of HER3-targeted drugs possessing safety, tolerability, and sensitivity is crucial for clinical cancer treatment. This review summarizes the progress of the mechanism of HER3 in drug resistance, the HER3-targeted therapies that are conducted in preclinical and clinical trials, and some emerging molecules that could be used as future designed drugs for HER3, aiming to provide insights for future research and development of anticancer drugs targeting HER3.

Novel Thienoduocarmycin-Trastuzumab ADC Demonstrates Strong Antitumor Efficacy with Favorable Safety Profile in Preclinical Studies

New antibodies-drug conjugate (ADC) payloads overcoming chemoresistance and killing also poorly proliferating tumors at well-tolerated doses are much desired. Duocarmycins are a well-known class of highly potent cytotoxic agents, with DNA minor groove-binding and alkylation properties, active also in chemoresistant tumors. Although different duocarmycin derivatives have been used during the years as payloads for ADC production, unfavorable physicochemical properties impaired the production of ADCs with optimal features. Optimization of the toxin to balance reactivity and stability features and best linker selection allowed us to develop the novel duocarmycin-like payload-linker NMS-P945 suitable for conjugation to mAbs with reproducible drug-antibody ratio (DAR) >3.5. When conjugated to trastuzumab, it generated an ADC with good internalization properties, ability to induce bystander effect and immunogenic cell death. Moreover, it showed strong target-driven activity in cells and cytotoxic activity superior to trastuzumab deruxtecan tested, in parallel, in cell lines with HER2 expression. High in vivo efficacy with cured mice at well-tolerated doses in HER2-driven models was also observed. A developed pharmacokinetic/pharmacodynamic (PK/PD) model based on efficacy in mice and cynomolgus monkey PK data, predicted tumor regression in patients upon administration of 2 doses of trastuzumab-NMS-P945-ADC at 0.5 mg/kg. Thus, considering the superior physicochemical features for ADC production and preclinical results obtained with the model trastuzumab ADC, including bystander effect, immunogenic cell death and activity in chemoresistant tumors, NMS-P945 represents a highly effective, innovative payload for the creation of novel, next-generation ADCs.

HER-3 surface expression increases in advanced colorectal cancer representing a potential therapeutic target

HER-3 (also known as ErbB-3) is a human epidermal growth factor receptor tyrosine kinases family member, and its expression in CRC (colorectal cancer) tissues was previously associated with poor prognosis. In this study, HER-3 expression was analyzed by immunohistochemistry in two cohorts of early and advanced metastatic CRC patients. The first cohort included 180 patients diagnosed with CRC in absence of lymph nodes or distant metastases (Stage I and Stage II), while the second was obtained from 53 advanced metastatic CRC patients who developed synchronous (SM) and metachronous (MM) liver metastases. In the first early-stage CRC cohort, 86 out of 180 (47.8%) tumors showed membranous expression of HER-3, with a mean percentage of positive tumor cells of 25.7%; conversely, in advanced metastatic CRC primary tumors, HER-3 was detected in all specimens, with a mean percentage of positive tumor cells of 76.1%. Kaplan-Meier curves showed that in the advanced metastatic CRC group, patients with HER-3high tumors had a significantly lower Cancer-Specific Survival (CSS) rate compared to patients with HER-3low tumors (p = 0.021). Importantly, this worse CSS rate was observed only in the MM subgroup of patients with HER-3high tumors (p = 0.002). Multivariate analysis confirmed that high HER-3 expression represents a significant and strong risk factor for death in patients developing MM liver metastases (Hazard Ratio = 64.9; 95% Confidence Interval, 4.7-886.6; p = 0.002). In addition, using a specific anti-HER-3 antibody-drug conjugate, named EV20/MMAF, we showed that HER-3 + CRC cells can be efficiently targeted in vitro and in vivo. Overall, this study confirms that surface HER-3 is highly expressed in CRC and reveals that HER-3 expression increases in metastatic CRC patients compared to early stage. Importantly, the results suggest that HER-3 has a prognostic and therapeutic value in patients developing MM liver metastases.

Antibody drug conjugates: hitting the mark in pancreatic cancer?

Pancreatic cancer is one of the most common causes of cancer-related death, and the 5-year survival rate has only improved marginally over the last decade. Late detection of the disease means that in most cases the disease has advanced locally and/or metastasized, and curative surgery is not possible. Chemotherapy is still the first-line treatment however, this has only had a modest impact in improving survival, with associated toxicities. Therefore, there is an urgent need for targeted approaches to better treat pancreatic cancer, while minimizing treatment-induced side-effects. Antibody drug conjugates (ADCs) are one treatment option that could fill this gap. Here, a monoclonal antibody is used to deliver extremely potent drugs directly to the tumor site to improve on-target killing while reducing off-target toxicity. In this paper, we review the current literature for ADC targets that have been examined in vivo for treating pancreatic cancer, summarize current and on-going clinical trials using ADCs to treat pancreatic cancer and discuss potential strategies to improve their therapeutic window.

AMT-562, a Novel HER3-targeting Antibody-Drug Conjugate, Demonstrates a Potential to Broaden Therapeutic Opportunities for HER3-expressing Tumors

HER3 is a unique member of the EGFR family of tyrosine kinases, which is broadly expressed in several cancers, including breast, lung, pancreatic, colorectal, gastric, prostate, and bladder cancers and is often associated with poor patient outcomes and therapeutic resistance. U3-1402/Patritumab-GGFG-DXd is the first successful HER3-targeting antibody-drug conjugate (ADC) with clinical efficacy in non-small cell lung cancer. However, over 60% of patients are nonresponsive to U3-1402 due to low target expression levels and responses tend to be in patients with higher target expression levels. U3-1402 is also ineffective in more challenging tumor types such as colorectal cancer. AMT-562 was generated by a novel anti-HER3 antibody Ab562 and a modified self-immolative PABC spacer (T800) to conjugate exatecan. Exatecan showed higher cytotoxic potency than its derivative DXd. Ab562 was selected because of its moderate affinity for minimizing potential toxicity and improving tumor penetration purposes. Both alone or in combination therapies, AMT-562 showed potent and durable antitumor response in low HER3 expression xenograft and heterogeneous patient-derived xenograft/organoid models, including digestive system and lung tumors representing of unmet needs. Combination therapies pairing AMT-562 with therapeutic antibodies, inhibitors of CHEK1, KRAS, and tyrosine kinase inhibitor showed higher synergistic efficacy than Patritumab-GGFG-DXd. Pharmacokinetic and safety profiles of AMT-562 were favorable and the highest dose lacking severe toxicity was 30 mg/kg in cynomolgus monkeys. AMT-562 has potential to be a superior HER3-targeting ADC with a higher therapeutic window that can overcome resistance to generate higher percentage and more durable responses in U3-1402-insensitive tumors.

HER3 in cancer: from the bench to the bedside

The HER3 protein, that belongs to the ErbB/HER receptor tyrosine kinase (RTK) family, is expressed in several types of tumors. That fact, together with the role of HER3 in promoting cell proliferation, implicate that targeting HER3 may have therapeutic relevance. Furthermore, expression and activation of HER3 has been linked to resistance to drugs that target other HER receptors such as agents that act on EGFR or HER2. In addition, HER3 has been associated to resistance to some chemotherapeutic drugs. Because of those circumstances, efforts to develop and test agents targeting HER3 have been carried out. Two types of agents targeting HER3 have been developed. The most abundant are antibodies or engineered antibody derivatives that specifically recognize the extracellular region of HER3. In addition, the use of aptamers specifically interacting with HER3, vaccines or HER3-targeting siRNAs have also been developed. Here we discuss the state of the art of the preclinical and clinical development of drugs aimed at targeting HER3 with therapeutic purposes.

Research Progress of Antibody–Drug Conjugate Therapy for Advanced Gastric Cancer

Gastric cancer is an intractable malignant tumor that has the fifth highest morbidity and the third highest mortality in the world. Even though various treatment options did much to ameliorate the prognosis of advanced gastric cancer, the survival time remained unsatisfactory. It is significant to develop new therapeutic agents to improve the long-term outcome. Antibody–drug conjugate is an innovative and potent antineoplastic drug composed of a specifically targeted monoclonal antibody, a chemical linker, and a small molecule cytotoxic payload. Powerful therapeutic efficacy and moderate toxicity are its preponderant advantages, which imply the inevitable pharmaceutical developments to meet the demand for individualized precision therapy. Nevertheless, it is unavoidable that there is a phenomenon of drug resistance in this agent. This article systematically reviewed the recent progress of antibody–drug conjugates in advanced gastric cancer therapy.

A Novel Monoclonal Antibody Targeting Cancer-Specific Plectin Has Potent Antitumor Activity in Ovarian Cancer

Cancer-specific plectin (CSP) is a pro-tumorigenic protein selectively expressed on the cell surface of major cancers, including ovarian cancer (OC). Despite its assessable localization, abundance, and functional significance, the therapeutic efficacy of targeting CSP remains unexplored. Here, we generated and investigated the anticancer effects of a novel CSP-targeting monoclonal antibody, 1H11, in OC models. Its therapeutic efficacy as a monotherapy and in combination with chemotherapy was evaluated in vitro using two OC cell lines and in vivo by a subcutaneous ovarian cancer model. 1H11 demonstrated rapid internalization and high affinity and specificity for both human and murine CSP. Moreover, 1H11 induced significant and selective cytotoxicity (EC₅₀ = 260 nM), G0/G1 arrest, and decreased OC cell migration. Mechanistically, these results are associated with increased ROS levels and reduced activation of the JAK2-STAT3 pathway. In vivo, 1H11 decreased Ki67 expression, induced 65% tumor growth inhibition, and resulted in 30% tumor necrosis. Moreover, 1H11 increased chemosensitivity to cisplatin resulting in 60% greater tumor growth inhibition compared to cisplatin alone. Taken together, CSP-targeting with 1H11 exhibits potent anticancer activity against ovarian cancer and is deserving of future clinical development.