Mechanisms of Resistance to Antibody-Drug Conjugates

PI3K PROTAC overcomes the lapatinib resistance in PIK3CA-mutant HER2 positive breast cancer

Although anti-HER2 therapy has made significant strides in reducing metastasis and relapse in HER2-positive breast cancer, resistance to agents like trastuzumab, pertuzumab, and lapatinib frequently develops in patients undergoing treatment. Previous studies suggest that the hyperactivation of the PI3K-AKT signaling pathway by PIK3CA/PTEN gene mutations is implicated in HER2 resistance. In this study, we introduce a novel PI3K-p110α Proteolysis TAargeting Chimera (PROTAC) that effectively inhibits the proliferation of breast cancer cells by degrading PI3K-p110α. When tested in two lapatinib-resistant cell lines, JIMT1 and MDA-MB-453, both of which harbor PIK3CA mutations, the PI3K PROTAC notably reduced cell proliferation and induced G1 phase cell cycle arrest. Importantly, even at very low concentrations, PI3K PROTAC restored sensitivity to lapatinib. Furthermore, the efficacy of PI3K PROTAC surpassed that of Alpelisib, a selective PI3K-p110α kinase inhibitor in clinic. The superior performance of PI3K PROTAC was also confirmed in lapatinib-resistant breast cancer xenograft tumors and patient-derived breast cancer organoids (PDOs). In conclusion, this study reveals that the novel PI3K PROTAC we synthesized could serve as an effective agent to overcome lapatinib resistance.

Antibody-drug conjugates in cancer therapy: mechanisms and clinical studies

Antibody-drug conjugates (ADCs) consist of monoclonal antibodies that target tumor cells and cytotoxic drugs linked through linkers. By leveraging antibodies' targeting properties, ADCs deliver cytotoxic drugs into tumor cells via endocytosis after identifying the tumor antigen. This precise method aims to kill tumor cells selectively while minimizing harm to normal cells, offering safe and effective therapeutic benefits. Recent years have seen significant progress in antitumor treatment with ADC development, providing patients with new and potent treatment options. With over 300 ADCs explored for various tumor indications and some already approved for clinical use, challenges such as resistance due to factors like antigen expression, ADC processing, and payload have emerged. This review aims to outline the history of ADC development, their structure, mechanism of action, recent composition advancements, target selection, completed and ongoing clinical trials, resistance mechanisms, and intervention strategies. Additionally, it will delve into the potential of ADCs with novel markers, linkers, payloads, and innovative action mechanisms to enhance cancer treatment options. The evolution of ADCs has also led to the emergence of combination therapy as a new therapeutic approach to improve drug efficacy.

Unlocking the potential of bispecific ADCs for targeted cancer therapy

Antibody-drug conjugates (ADCs) are biologically targeted drugs composed of antibodies and cytotoxic drugs connected by linkers. These innovative compounds enable precise drug delivery to tumor cells, minimizing harm to normal tissues and offering excellent prospects for cancer treatment. However, monoclonal antibody-based ADCs still present challenges, especially in terms of balancing efficacy and safety. Bispecific antibodies are alternatives to monoclonal antibodies and exhibit superior internalization and selectivity, producing ADCs with increased safety and therapeutic efficacy. In this review, we present available evidence and future prospects regarding the use of bispecific ADCs for cancer treatment, including a comprehensive overview of bispecific ADCs that are currently in clinical trials. We offer insights into the future development of bispecific ADCs to provide novel strategies for cancer treatment.

Antibody-Drug Conjugates: The New Treatment Approaches for Ovarian Cancer

Ovarian cancer (OC), accounting for approximately 200,000 deaths worldwide annually, is a heterogeneous disease showing major differences in terms of its incidence, tumor behavior, and outcomes across histological subtypes. In OC, primary chemotherapy, paclitaxel carboplatin, bevacizumab, and PARP inhibitors have shown prolonged progression-free survival and a favorable overall response rate compared to conventional treatments. However, treatment options for platinum-resistant recurrence cases are limited, with no effective therapies that significantly prolong the prognosis. Recently, mirvetuximab soravtansine, an alpha-folate receptor (FRα)-targeted antibody-drug conjugate (ADC), was approved by the US Food and Drug Administration for patients with FRα-positive recurrent epithelial OC (EOC). This approval was based on a Phase II study, which demonstrated its efficacy in such patients. ADCs comprise an antibody, a linker, and a payload, representing new concept agents without precedence. Advanced clinical studies are developing ADCs for patients with OC, targeting solid tumors such as gynecologic cancer. Ongoing clinical trials are evaluating ADCs targeting FRα and human epidermal growth factor receptor 2, trophoblast cell surface antigen-2, sodium-dependent phosphate transport protein 2B, and cadherin-6 in Phase II/III studies. In this review, we summarize the existing evidence supporting the use of ADCs in OC, discuss ongoing clinical trials and preclinical studies, and explore the potential of these innovative agents to address the challenges in OC treatment.

Antibody-Drug Conjugates to Promote Immune Surveillance: Lessons Learned from Breast Cancer

Antibody-drug conjugates (ADCs) represent an effective class of agents for the treatment of several tumor types, including breast cancer (BC), featuring approved molecules such as trastuzumab-emtansine, trastuzumab-deruxtecan, and sacituzumab-govitecan. Immune-checkpoint inhibitors (ICIs) also showed activity in selected BC subtypes, and two agents, pembrolizumab and atezolizumab, are currently approved for the treatment of triple-negative BC patients. The potential synergy between ADCs and immunotherapy in BC remains an area of active investigation. Preclinical studies suggest that ADCs promote immune surveillance, modulating tumor microenvironment, inducing immunogenic cell death, and enhancing antitumor immunity. Translational evidence has shown potential predictive biomarkers for ADCs alone or in combination with immunotherapy, including expression of target antigen, oncogenic pathways, tumor-infiltrating lymphocytes, and neutrophil-to-lymphocyte ratio. Given this background, several clinical trials evaluated ADC-ICI combinations in BC patients, demonstrating promising outcomes with an overall manageable toxicity profile, and many studies are currently ongoing to confirm the efficacy and feasibility of this therapeutic approach. In the present review, we summarized the available evidence about the integration of ADCs and immunotherapy for the management of BC, emphasizing the need for further translational and clinical investigations to optimize this treatment strategy and elucidate predictive biomarkers, eventually improving patient outcomes.

Spotlight on ideal target antigens and resistance in antibody-drug conjugates: Strategies for competitive advancement

Antibody-drug conjugates (ADCs) represent a novel and promising approach in targeted therapy, uniting the specificity of antibodies that recognize specific antigens with payloads, all connected by the stable linker. These conjugates combine the best targeted and cytotoxic therapies, offering the killing effect of precisely targeting specific antigens and the potent cell-killing power of small molecule drugs. The targeted approach minimizes the off-target toxicities associated with the payloads and broadens the therapeutic window, enhancing the efficacy and safety profile of cancer treatments. Within precision oncology, ADCs have garnered significant attention as a cutting-edge research area and have been approved to treat a range of malignant tumors. Correspondingly, the issue of resistance to ADCs has gradually come to the fore. Any dysfunction in the steps leading to the ADCs' action within tumor cells can lead to the development of resistance. A deeper understanding of resistance mechanisms may be crucial for developing novel ADCs and exploring combination therapy strategies, which could further enhance the clinical efficacy of ADCs in cancer treatment. This review outlines the brief historical development and mechanism of ADCs and discusses the impact of their key components on the activity of ADCs. Furthermore, it provides a detailed account of the application of ADCs with various target antigens in cancer therapy, the categorization of potential resistance mechanisms, and the current state of combination therapies. Looking forward, breakthroughs in overcoming technical barriers, selecting differentiated target antigens, and enhancing resistance management and combination therapy strategies will broaden the therapeutic indications for ADCs. These progresses are anticipated to advance cancer treatment and yield benefits for patients.

Antibody-Drug Conjugates in Urothelial Cancer: From Scientific Rationale to Clinical Development

Antibody-drug conjugates (ADCs) have been a significant advancement in cancer therapy, particularly for urothelial cancer (UC). These innovative treatments, originally developed for hematological malignancies, use target-specific monoclonal antibodies linked to potent cytotoxic agents. This rational drug design efficiently delivers cancer cell-killing agents to cells expressing specific surface proteins, which are abundant in UC owing to their high antigen expression. UC is an ideal candidate for ADC therapy, as it enhances on-target efficacy while mitigating systemic toxicity. In recent years, considerable progress has been made in understanding the biology and mechanisms of tumor progression in UC. However, despite the introduction of immune checkpoint inhibitors, advanced UC is characterized by rapid progression and poor survival rates. Targeted therapies that have been developed include the anti-nectin 4 ADC enfortumab vedotin and the fibroblast growth factor receptor inhibitor erdafitinib. Enfortumab vedotin has shown efficacy in prospective studies in patients with advanced UC, alone and in combination with pembrolizumab. The anti-Trop-2 ADC sacituzumab govitecan has also demonstrated effectiveness in single-armed studies. This review highlights the mechanism of action of ADCs, their application in mono- and combination therapies, primary mechanisms of resistance, and future perspectives for their clinical use in UC treatment. ADCs have proven to be an increasingly vital component of the therapeutic landscape for urothelial carcinoma, filling a gap in the treatment of this progressive disease.

Epidermal Growth Factor Receptor Targeting in Colorectal Carcinoma: Antibodies and Patient-Derived Organoids as a Smart Model to Study Therapy Resistance

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. Therefore, the need for new therapeutic strategies is still a challenge. Surgery and chemotherapy represent the first-line interventions; nevertheless, the prognosis for metastatic CRC (mCRC) patients remains unacceptable. An important step towards targeted therapy came from the inhibition of the epidermal growth factor receptor (EGFR) pathway, by the anti-EGFR antibody, Cetuximab, or by specific tyrosine kinase inhibitors (TKI). Cetuximab, a mouse-human chimeric monoclonal antibody (mAb), binds to the extracellular domain of EGFR thus impairing EGFR-mediated signaling and reducing cell proliferation. TKI can affect the EGFR biochemical pathway at different steps along the signaling cascade. Apart from Cetuximab, other anti-EGFR mAbs have been developed, such as Panitumumab. Both antibodies have been approved for the treatment of KRAS-NRAS wild type mCRC, alone or in combination with chemotherapy. These antibodies display strong differences in activating the host immune system against CRC, due to their different immunoglobulin isotypes. Although anti-EGFR antibodies are efficient, drug resistance occurs with high frequency. Resistant tumor cell populations can either already be present before therapy or develop later by biochemical adaptations or new genomic mutations in the EGFR pathway. Numerous efforts have been made to improve the efficacy of the anti-EGFR mAbs or to find new agents that are able to block downstream EGFR signaling cascade molecules. Indeed, we examined the importance of analyzing the anti-EGFR antibody-drug conjugates (ADC) developed to overcome resistance and/or stimulate the tumor host's immunity against CRC growth. Also, patient-derived CRC organoid cultures represent a useful and feasible in vitro model to study tumor behavior and therapy response. Organoids can reflect tumor genetic heterogeneity found in the tissue of origin, representing a unique tool for personalized medicine. Thus, CRC-derived organoid cultures are a smart model for studying the tumor microenvironment and for the preclinical assay of anti-EGFR drugs.

Safety, Efficacy, and Pharmacokinetics of SHR-A1811, a Human Epidermal Growth Factor Receptor 2-Directed Antibody-Drug Conjugate, in Human Epidermal Growth Factor Receptor 2-Expressing or Mutated Advanced Solid Tumors: A Global Phase I Trial

PURPOSE

SHR-A1811 is an antibody-drug conjugate composed of an anti-human epidermal growth factor receptor 2 (HER2) antibody trastuzumab, a cleavable linker, and a topoisomerase I inhibitor payload. We assessed the safety, tolerability, antitumor activity, and pharmacokinetics of SHR-A1811 in heavily pretreated HER2-expressing or mutated advanced solid tumors.

METHODS

This global, multi-center, first-in-human, phase I trial was conducted at 33 centers. Patients who had HER2-expressing or mutated unresectable, advanced, or metastatic solid tumors and were refractory or intolerant to standard therapies were enrolled. SHR-A1811 was administered intravenously at doses ranging from 1.0 to 8.0 mg/kg once every 3 weeks. The primary end points were dose-limiting toxicity, safety, and the recommended phase II dose.

RESULTS

From September 7, 2020, to February 27, 2023, 307 patients who had undergone a median of three (IQR, 2-5) previous treatment regimens in the metastatic setting received SHR-A1811 treatment. As of data cutoff (February 28, 2023), one patient from the 6.4 mg/kg group experienced dose-limiting toxicities (pancytopenia and colitis). The most common grade 3 or higher adverse events (AEs) included decreased neutrophil count (119 [38.8%]) and decreased WBC count (70 [22.8%]). Interstitial lung disease occurred in only eight (2.6%) patients. Serious AEs and deaths occurred in 70 (22.8%) and 13 (4.2%) patients, respectively. SHR-A1811 led to objective responses in 59.9% (184/307) of all patients, 76.3% (90/118) of HER2-positive breast cancer, 60.4% (55/91) of HER2 low-expressing breast cancer, and 45.9% (39/85 with evaluable tumor responses) of the 98 nonbreast tumors.

CONCLUSION

SHR-A1811 exhibited acceptable tolerability, promising antitumor activity, and a favorable pharmacokinetic profile in heavily pretreated advanced solid tumors. The recommended phase II dose of 4.8 or 6.4 mg/kg was selected for various tumor types.

[Research Progress of Antibody-conjugated Drugs in Non-small Cell Lung Cancer]

Lung cancer is the most common malignant tumor and the second most common malignant tumor in terms of mortality in the world. Non-small cell lung cancer (NSCLC) is the most common pathological type of lung cancer. Currently, the first-line standard treatment for advanced NSCLC is immunotherapy and targeted therapy. Although these treatments prolong the survival of patients, acquired drug resistance is still inevitable. Antibody-drug conjugates (ADCs) are a new type of anti-tumor drug made by coupling cytotoxic payloads to specific monoclonal antibodies via linkers. Compared with chemotherapy drugs, ADCs have the advantages of accurate recognition, local release, and high patient tolerance. In recent years, they have shown good clinical benefits in the treatment of NSCLC. This article provides an overview of the mechanism of action of ADCs, clinical studies progress in advanced NSCLC, and existing problems and challenges.
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Mechanisms of action and resistance to anti-HER2 antibody-drug conjugates in breast cancer

Human epidermal growth factor 2 (HER2)-positive breast cancer (BC) represents nearly 20% of all breast tumors. Historically, these patients had a high rate of relapse and dismal prognosis. The advent of HER2-targeting monoclonal antibodies such as trastuzumab followed by pertuzumab had improved the prognosis of HER2-positive metastatic BC. More recently, antibody-drug conjugates (ADCs) are now reshaping the treatment paradigm of solid tumors, especially breast cancer. Tratsuzumab emtansine (T-DM1) was one of the first ADC developed in oncology and was approved for the management of HER2-positive metastatic BC. In a head-to-head comparison, trastuzumab deruxtecan (T-DXd) defeated T-DM1 as a second-line treatment. The efficacy of ADCs is counterbalanced by the appearance of acquired resistance to these agents. In this paper, we summarize the mechanisms of action and resistance of T-DM1 and T-DXd, as well as their clinical efficacy. Additionally, we also discuss potential strategies for addressing resistance to ADC.

Design, synthesis and bioactivity evaluation of novel monomethyl auristatin F analogues

Monomethyl auristatin F (MMAF), a synthetic analogue of the natural compound dolastatin 10, has garnered significant attention in cancer research due to its high potency in vitro. While previous studies have focused on modifying the N-terminal extension of the amino group and the C-terminal modification of the carboxyl group, there has been limited exploration into modifying the P1 and P5 side chains. In this study, we substituted the valine residue at the P1 position with various natural or unnatural amino acids and introduced triazole functional groups at the P5 side chain. Compounds 11k and 18d exhibited excellent inhibition on tubulin. Additionally, compound 18d demonstrated enhanced cytotoxicity against HCT116 cells compared to the parent compound MMAF, suggesting its potential as a cytotoxic payload for further antibody-drug conjugates (ADCs) development.

The Evolution of Antibody-Drug Conjugates: Toward Accurate DAR and Multi-specificity

Antibody-drug conjugates (ADCs) consist of antibodies, linkers and payloads. They offer targeted delivery of potent cytotoxic drugs to tumor cells, minimizing off-target effects. However, the therapeutic efficacy of ADCs is compromised by heterogeneity in the drug-to-antibody ratio (DAR), which impacts both cytotoxicity and pharmacokinetics (PK). Additionally, the emergence of drug resistance poses significant challenges to the clinical advancement of ADCs. To overcome these limitations, a variety of strategies have been developed, including the design of multi-specific drugs with accurate DAR. This review critically summarizes the current challenges faced by ADCs, categorizing key issues and evaluating various innovative solutions. We provide an in-depth analysis of the latest methodologies for achieving homogeneous DAR and explore design strategies for multi-specific drugs aimed at combating drug resistance. Our discussion offers a current perspective on the advancements made in refining ADC technologies, with an emphasis on enhancing therapeutic outcomes.

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

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

Pioneering the Way: The Revolutionary Potential of Antibody-Drug Conjugates in NSCLC

OPINION STATEMENT

Despite targeted therapy and immunotherapy being recognized as established frontline treatments for advanced non-small cell lung cancer (NSCLC), the unavoidable development of resistance and disease progression poses ongoing challenges. Antibody-drug conjugates (ADCs) offer a potent treatment option for NSCLC through the specific delivery of cytotoxic agents to tumor cells that display distinct antigens. This review delves into the latest evidence regarding promising ADC agents for NSCLC, focusing on their targets, effectiveness, and safety assessments. Additionally, our study provides insights into managing toxicities, identifying biomarkers, devising methods to counter resistance mechanisms, tackling prevailing challenges, and outlining prospects for the clinical implementation of these innovative ADCs and combination regimens in NSCLC.

Antibody-Drug Conjugate Overview: a State-of-the-art Manufacturing Process and Control Strategy

Antibody-drug conjugates (ADCs) comprise an antibody, linker, and drug, which direct their highly potent small molecule drugs to target tumor cells via specific binding between the antibody and surface antigens. The antibody, linker, and drug should be properly designed or selected to achieve the desired efficacy while minimizing off-target toxicity. With a unique and complex structure, there is inherent heterogeneity introduced by product-related variations and the manufacturing process. Here this review primarily covers recent key advances in ADC history, clinical development status, molecule design, manufacturing processes, and quality control. The manufacturing process, especially the conjugation process, should be carefully developed, characterized, validated, and controlled throughout its lifecycle. Quality control is another key element to ensure product quality and patient safety. A patient-centric strategy has been well recognized and adopted by the pharmaceutical industry for therapeutic proteins, and has been successfully implemented for ADCs as well, to ensure that ADC products maintain their quality until the end of their shelf life. Deep product understanding and process knowledge defines attribute testing strategies (ATS). Quality by design (QbD) is a powerful approach for process and product development, and for defining an overall control strategy. Finally, we summarize the current challenges on ADC development and provide some perspectives that may help to give related directions and trigger more cross-functional research to surmount those challenges.

First experience in treating advanced urothelial cancer with enfortumab vedotin. Single-centre retrospective study of patients qualified for a rescue access procedure

Introduction

Urothelial carcinoma is the most common type of urinary tract malignancy. Current treatment options, including platinum-based chemotherapy or immunotherapy, present significant challenges, ranging from limited efficacy to severe toxicities. Recent developments in antibody-drug conjugates (ADC), such as enfortumab vedotin (EV), promise to significantly improve overall survival. The study aims to evaluate the efficacy and tolerability of EV. In addition, we highlight the observed benefits of next-line treatment after progression.

Material and methods

This retrospective study involved 16 patients with advanced urothelial cancer treated with EV at the Department of Genitourinary Oncology, Maria Skłodowska- Curie National Research Institute of Oncology between November 2022 and November 2023. The study evaluated patients' medical history, response to EV treatment, and side effects. Notably, the study included patients who had already exhausted standard treatment options and who were treated with EV through a rescue access procedure.

Results

Partial response was observed in 4 out of 9 (44%) patients with available imaging. Common terminology criteria for adverse events (AE) grade 3 and 4 were observed in 3 out of 16 patients, which subsequently required dose reduction.

Conclusions

Enfortumab vedotin demonstrates effectiveness in real-world settings in treating advanced urothelial cancer. Proper management of AE in experienced centres may further prolong survival. Personalized treatment and the development of new ADC represent the future for improved patient outcomes.

Antitumor activities against breast cancers by an afucosylated anti-HER2 monoclonal antibody H2 Mab-77-mG2a -f

Breast cancer patients with high levels of human epidermal growth factor receptor 2 (HER2) expression have worse clinical outcomes. Anti-HER2 monoclonal antibody (mAb) is the most important therapeutic modality for HER2-positive breast cancer. We previously immunized mice with the ectodomain of HER2 to create the anti-HER2 mAb, H2 Mab-77 (mouse IgG1 , kappa). This was then altered to produce H2 Mab-77-mG2a -f, an afucosylated mouse IgG2a . In the present work, we examined the reactivity of H2 Mab-77-mG2a -f and antitumor effects against breast cancers in vitro and in vivo. BT-474, an endogenously HER2-expressing breast cancer cell line, was identified by H2 Mab-77-mG2a -f with a strong binding affinity (a dissociation constant [KD ]: 5.0 × 10-9  M). H2 Mab-77-mG2a -f could stain HER2 of breast cancer tissues in immunohistochemistry and detect HER2 protein in Western blot analysis. Furthermore, H2 Mab-77-mG2a -f demonstrated strong antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) for BT-474 cells. MDA-MB-468, a HER2-negative breast cancer cell line, was unaffected by H2 Mab-77-mG2a -f. Additionally, in the BT-474-bearing tumor xenograft model, H2 Mab-77-mG2a -f substantially suppressed tumor development when compared with the control mouse IgG2a mAb. In contrast, the HER2-negative MDA-MB-468-bearing tumor xenograft model showed no response to H2 Mab-77-mG2a -f. These findings point to the possibility of H2 Mab-77-mG2a -f as a treatment regimen by showing that it has antitumor effects on HER2-positive breast tumors.

Systematic review of recent advancements in antibody-drug and bicycle toxin conjugates for the treatment of urothelial cancer

Antibody-drug conjugates and bicycle toxin conjugates represent a tremendous advance in drug delivery technology and have shown great promise in the treatment of urothelial cancer. Previously approved systemic therapies, including chemotherapy and immunotherapy, are often impractical due to comorbidities, and outcomes for patients with advanced disease remain poor, even when receiving systemic therapy. In this setting, antibody-drug and bicycle toxin conjugates have emerged as novel treatments, dramatically altering the therapeutic landscape. These drugs harness unique designs consisting of antibody or bicycle peptide, linker, and cytotoxic payload with more targeted delivery than conventional chemotherapy, thus eliminating malignant cells while reducing systemic toxicities. Potential targets investigated in urothelial cancer include Nectin-4, TROP2, HER2, and EphA2. Initial clinical trials demonstrated efficacy in treatment of refractory advanced urothelial cancer, as well as improvement in quality of life. These initial studies led to FDA approval of two antibody-drug conjugates, enfortumab vedotin and sacituzumab govitecan. Moreover, antibody-drug and bicycle toxin conjugates are being studied in ongoing clinical trials in frontline treatment of advanced disease as well as for localized cancer. These studies highlight the potential for additional future therapies with novel targets, novel antibodies, cytotoxic and immunomodulatory payloads, and unique structural designs enhancing efficacy and safety. There is increasing evidence that combinations with other cancer therapies, especially immunotherapy, improve treatment outcomes. The combination of enfortumab vedotin and pembrolizumab was recently approved for first-line treatment of advanced urothelial carcinoma. Despite the great promise of these novel drugs, robust predictive biomarkers are needed to determine the patients who would maximally benefit. This review surveys the rationale and current state of the evidence for these new drugs and describes future directions actively being explored.

TRPML1 as a potential therapeutic target for triple-negative breast cancer: a review

Triple-negative breast cancer (TNBC) is the most refractory subtype of breast cancer, and effective treatments are urgently needed owing to its poor prognosis. Surgery, radiotherapy, and chemotherapy, alone or in combination, are the leading choices for TNBC therapy. Although promising approaches and procedures have emerged, several challenges, such as off-target effects, drug resistance, and severe side effects, remain to be addressed. Recently, transient receptor potential channel mucolipin 1 (TRPML1) has attracted the attention of researchers because its expression has been implicated in numerous diseases, including cancer. TRPML1 regulates biological events and signaling pathways, including autophagic flux, exocytosis, ionic homeostasis, and lysosomal biogenesis, all contributing to tumorigenesis and cancer progression. TRPML1 also functions as a building block for cancer cell growth, mitogenic signaling, priming tissues for metastasis, and activation of transcriptional programs, processes involved in several malignant tumors. This review provides an overview of breast cancer epidemiology and diagnostic techniques and then discusses the existing therapeutics. Additionally, we elaborate on the development of, and associated challenges to, TNBC diagnostics and treatment and the feasibility of TRPML1 as a therapeutic target for TNBC.

Durable Response After Combination Therapy With Enfortumab Vedotin and Radiotherapy in Metastatic Urothelial Carcinoma: A Report of Two Cases

Enfortumab vedotin for urothelial carcinoma is a potentially effective anti-tumor drug that can be used in 3rd-line therapy or later, even in relatively advanced stages of the disease. Here, we present two cases of treatment using enfortumab vedotin with subsequent radiotherapy for primary lesions, and long-term disease control was achieved. The first case involved a 78-year-old man previously treated with pembrolizumab following gemcitabine plus carboplatin for lower ureteral carcinoma with multiple lung and lymph node metastases. Six months after the initiation of enfortumab vedotin, the primary tumor and metastases notably shrank. However, the primary tumor regrew, and radiotherapy was initiated along with enfortumab vedotin. The second case involved a 60-year-old man who was initially treated with avelumab following gemcitabine plus cisplatin for bladder cancer with multiple lymph node metastases. After two months of enfortumab vedotin, the primary and metastatic lesions shrunk. However, the primary tumor regrew, and radiotherapy was initiated. In both cases, the primary tumor and metastases recorded long-term shrinkage. The combination of radiotherapy and enfortumab vedotin may be an effective treatment option.

Exploring the therapeutic potential of ADC combination for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer. Currently, standard treatment options for TNBC are limited to surgery, adjuvant chemotherapy, and radiotherapy. However, these treatment methods are associated with a higher risk of intrinsic or acquired recurrence. Antibody-drug conjugates (ADCs) have emerged as a useful and promising class of cancer therapeutics. ADCs, also known as "biochemical missiles", use a monoclonal antibody (mAb) to target tumor antigens and deliver a cytotoxic drug payload. Currently, several ADCs clinical studies are underway worldwide, including sacituzumab govitecan (SG), which was recently approved by the FDA for the treatment of TNBC. However, due to the fact that only a small portion of TNBC patients respond to ADC therapy and often develop resistance, growing evidence supports the use of ADCs in combination with other treatment strategies to treat TNBC. In this review, we described the current utilization of ADCs and discussed the prospects of ADC combination therapy for TNBC.

The endosomal-lysosomal system in ADC design and cancer therapy

INTRODUCTION

This discourse delves into the intricate connections between the endosomal-lysosomal system and antibody-drug conjugates (ADCs), shedding light on an essential yet less understood dimension of targeted therapy. While ADCs have revolutionized cancer treatment, resistance remains a formidable challenge, often involving diverse and overlapping mechanisms.

AREAS COVERED

This discourse highlights the roles of various components within the endosomal machinery, including Rab proteins, in ADC resistance development. It also explores how the transferrin-transferrin receptor and epidermal growth factor-epidermal growth factor receptor complexes, known for their roles in recycling and degradation process, respectively, can offer valuable insights for ADC design. Selected strategies to enhance lysosomal targeting are discussed, and potentially offer solutions to improve ADC efficacy.

EXPERT OPINION

By harnessing these different insights that connect ADCs with the endosomal-lysosomal system, the field may benefit to shape the next-generation of ADC design for increased efficacy and improved patient outcomes.