First-in-Human Study of PF-06647020 (Cofetuzumab Pelidotin), an Antibody-Drug Conjugate Targeting Protein Tyrosine Kinase 7, in Advanced Solid Tumors

Prospects and challenges of CAR-T in the treatment of ovarian cancer

Ovarian cancer ranks as the seventh most prevalent cancer among women and is considered the most lethal gynecological malignancy on a global scale. The absence of reliable screening techniques, coupled with the insidious onset of nonspecific symptoms, often results in a delayed diagnosis, typically at an advanced stage characterized by peritoneal involvement. Management of advanced tumors typically involves a combination of chemotherapy and cytoreductive surgery. However, the therapeutic arsenal for ovarian cancer patients remains limited, highlighting the unmet need for precise, targeted, and sustained-release pharmacological agents. Genetically engineered T cells expressing chimeric antigen receptors (CARs) represent a promising novel therapeutic modality that selectively targets specific antigens, demonstrating robust and enduring antitumor responses in numerous patients. CAR T cell therapy has exhibited notable efficacy in hematological malignancies and is currently under investigation for its potential in treating various solid tumors, including ovarian cancer. Currently, numerous researchers are engaged in the development of novel CAR-T cells designed to target ovarian cancer, with subsequent evaluation of these candidate cells in preclinical studies. Given the ability of chimeric antigen receptor (CAR) expressing T cells to elicit potent and long-lasting anti-tumor effects, this therapeutic approach holds significant promise for the treatment of ovarian cancer. This review article examines the utilization of CAR-T cells in the context of ovarian cancer therapy.

Recent insights into the therapeutic strategies targeting the pseudokinase PTK7 in cancer

The generation of drugs counteracting deregulated protein kinases has been a major focus in cancer therapy development. Breakthroughs in this effort have produced many therapeutic agents to the benefit of patients, mostly through the development of chemical or antibody-based drugs targeting active kinases. These strategies are challenged when considering catalytically inactive protein kinases (or pseudokinases), which represent 10% of the human kinome with many of relevance in cancer. Among the so-called pseudotyrosine kinases, the PTK7 receptor tyrosine kinase (RTK) stands as a bona fide target overexpressed in several solid tumors and hematological malignancies and linked to metastasis, poor prognosis, and resistance to treatment. Despite the lack of catalytic activity, PTK7 has signaling capacities through heterodimerization with active RTKs and offers pharmacological targeting opportunities through its inactive kinase domain. Moreover, PTK7-targeting strategies based on antibody-drug conjugates, aptamers, and CAR-T cell-based therapies have demonstrated encouraging results in preclinical and clinical settings. We review the most recent data assigning to PTK7 a prominent role in cancer progression as well as current preclinical and clinical targeting strategies against RTK family pseudokinases including PTK7.

The evolving landscape of antibody-drug conjugates in ovarian cancer: new drugs for a new era

PURPOSE OF REVIEW

This review addresses the emerging role of antibody-drug conjugates (ADCs) in the treatment of ovarian cancer, a field marked by a high need for more effective and targeted therapies. Given the recent advancements in ADC technology and the ongoing challenges in treating ovarian cancer, particularly in late-stage and recurrent cases, this review is both timely and relevant. It synthesizes current research findings and clinical trial data, highlighting the potential of ADCs to revolutionize ovarian cancer treatment.

RECENT FINDINGS

The review covers key themes including the mechanism of action of ADCs, their specificity in targeting ovarian cancer cells, recent clinical trial outcomes, advancements in ADC design for improved efficacy and reduced toxicity, and strategies to overcome drug resistance in ovarian cancer. It also addresses the heterogeneity of ovarian cancer and the implications for personalized ADC therapies.

SUMMARY

The review underscores the potential of ADCs to significantly impact clinical practice, offering a more effective and personalized treatment approach for ovarian cancer patients. The review suggests a paradigm shift in the treatment of this malignancy, emphasizing the need for further research and development in this area.

Pharmacokinetics and pharmacodynamics of antibody-drug conjugates for the treatment of patients with breast cancer

INTRODUCTION

Currently three antibody-drug-conjugates (ADC) are approved by the European Medicines Agency (EMA) for treatment of breast cancer (BC) patient: trastuzumab-emtansine, trastuzumab-deruxtecan and sacituzumab-govitecan. ADC are composed of a monoclonal antibody (mAb) targeting a specific antigen, a cytotoxic payload and a linker. Pharmacokinetics (PK) and pharmacodynamics (PD) distinguish ADC from conventional chemotherapy and must be understood by clinicians.

AREAS COVERED

Our review delineates the PK/PD profiles of ADC approved for the treatment of BC with insight for future development. This is an expert opinion literature review based on the EMA's Assessment Reports, enriched by a comprehensive literature search performed on Medline in August 2023.

EXPERT OPINION

All three ADC distributions are described by a two-compartment structure: tissue and serum. Payload concentration peak is immediate but remains at low concentration. The distribution varied for all ADC only with body weight. mAb will be metabolised firstly by the saturable complex formation of ADC/Tumour-Receptor and secondly by binding of FcgRs in immune cells. They are all excreted in the bile and faeces with minimal urine elimination. Dose adjustments, apart from weight, are not recommended. Novel ADC are composed of cleavable linkers with various targets/payloads with the same PK/PD properties, but novel structures of ADC are in development.

The clinical development of antibody-drug conjugates for non-small cell lung cancer therapy

Despite the emergence of molecular targeted therapy and immune checkpoint inhibitors as standard first-line treatments for non-small cell lung cancer (NSCLC), their efficacy in some patients is limited by intrinsic and acquired resistance. Antibody-drug conjugates (ADCs), a revolutionary class of antitumor drugs, have displayed promising clinical outcomes in cancer treatment. In 2022, trastuzumab deruxtecan (Enhertu) was approved for treating HER2-mutated NSCLC, thereby underscoring the clinical value of ADCs in NSCLC treatment strategies. An increasing number of ADCs, focusing on NSCLC, are undergoing clinical trials, potentially positioning them as future treatment options. In this review, we encapsulate recent advancements in the clinical research of novel ADCs for treating NSCLC. Subsequently, we discuss the mechanisms of action, clinical efficacy, and associated limitations of these ADCs.

[Antibody drug conjugates (ADC) and bispecific antibodies in oncology - report of the 2022 Saint Louis day]

Antibody Drug Conjugates (ADC) and bispecific antibodies are booming and were the subject of the scientific event proposed by the French Society of Oncological Pharmacy, October 13, 2022. An ADC is composed of the antibody targeting a receptor expressed on the tumor cell, the spacer making it possible to attach the cytotoxic to the antibody and to control its distribution in the body, and the cytotoxic. Therapeutic antibodies, monoclonal and conjugated, have particular pharmacokinetics. Unlike monoclonal antibodies for which the standard dose is most often fixed, this is expressed in mg/m2 (or mg/kg) and capped at 2m2 (or 100kg) for conjugates. The linked cytotoxics are powerful cytotoxics: mitotic spindle poisons (emtansine, monomethyl auristatin E or vedotin), topoisomerase I inhibitors (deruxtecan, SN 38) or antibiotics (ozogamicin). In senology, trastuzumab deruxtecan (anti-HER2) and sacituzumab govitecan (anti-Trop 2) are now modifying treatment standards for patients with metastatic breast cancer, respectively HER2 3X or HER2 low and triple negative. In metastatic bladder cancer, enfortumab vedotin (anti-nectin 4) is positioned as the 2nd line of treatment. Bispecific antibodies, on the other hand, are able to target two epitopes, an antigen specific to a tumor cell and one to an immune cell, allowing a bridge between the killer immune cells and the tumor cells. For lymphoma proliferation, many bispecific antibodies are in development. The most advanced are glofitamab, epcoritamab and mosunetuzumab, which target the CD20 of B lymphocytes and the CD3 of T lymphocytes. Bispecific antibodies are also emerging in the treatment of myeloma with teclistamab and elranatamab (anti-CD3 and anti-BCMA) or talquetamab (anti-GPRC5D and anti-CD3). Conjugated antibodies, and more recently bispecific antibodies, are potential game changers in cancer treatment and researchs are needed to improve their efficacy and safety.

Antibody-drug conjugates in HER-2 negative breast cancers with poor prognosis

Antibody drug conjugates (ADCs) comprise a rapidly growing class of targeted drugs that selectively deliver a cytotoxic agent to cancer cells, reducing the side effects associated with conventional chemotherapy. Breast cancer (BC) is a heterogeneous entity. The need for effective therapies for HER-2 negative BCs with poor prognosis, such as triple-negative or endocrine-resistant BC, remains unmet due to the lack of potential targets for treatments. These BC subtypes are not candidates for hormonal or anti-HER-2 agents. However, ongoing clinical trials exploring the use of ADCs with a wide range of targets have shown potential for this treatment modality. In this review, we present the current state of knowledge regarding the role of ADC and speculate on novel approaches including ADC combination therapies, new molecular targets, and the role of other subclasses of ADCs (bicycle drug conjugates, bispecific ADCs, immune modulating ADCs) in this clinical scenario.

MTX-13, a Novel PTK7-Directed Antibody-Drug Conjugate with Widened Therapeutic Index Shows Sustained Tumor Regressions for a Broader Spectrum of PTK7-Positive Tumors

Protein tyrosine kinase 7 (PTK7) is a Wnt signaling pathway protein implicated in cancer development and metastasis. When using a potent microtubule inhibitor (Aur0101), PTK7-targeting antibody-drug conjugate (ADC), h6M24-vc0101 (PF-06647020/cofetuzumab pelidotin) is efficacious only in limited tumor types with low response rates in a phase I trial. To improve patient response and to expand responding tumor types, we designed MTX-13, a PTK7-targeting ADC consisting of a novel antibody (Ab13) conjugated to eight molecules of topoisomerase I inhibitor exatecan through T1000, a novel self-immolative moiety. MTX-13 exhibited PTK7-specific cell binding, efficient internalization, and exatecan release to cause cytotoxic activity through DNA damage and apoptosis induction, and a strong bystander killing. MTX-13 displayed potent antitumor activities on cell line-derived xenograft and patient-derived xenograft models from a wide range of solid tumors, significantly outperforming h6M24-vc0101. PTK7 was shown to be an actionable target in small cell lung cancer for which MTX-13 showed complete and durable responses. With a consistent overexpression of PTK7 in squamous cell carcinomas derived from diverse anatomic sites, strong potency of MTX-13 in this group of heterogenous tumors suggested a common treatment strategy. Finally, MTX-13 inhibited tumor growth and metastasis in an orthotopic colon cancer xenograft model. MTX-13 displayed a favorable pharmacokinetic and safety profile in monkeys with the highest non-severely toxic dose (HNSTD) of ≥30 mg/kg, significantly higher than 3-5 mg/kg of HNSTD for h6M24-vc0101. The higher therapeutic index of MTX-13 bodes well for its clinical translation with the potential to expand the responding patient population beyond that of current PTK7-targeting ADCs.

Targeted drug conjugate systems for ovarian cancer chemotherapy

Ovarian cancer is a highly lethal disease that affects women. Early diagnosis and treatment of women with early-stage disease improve the probability of survival. Unfortunately, the majority of women with ovarian cancer are diagnosed at advanced stages 3 and 4 which makes treatment challenging. While the majority of the patients respond to first-line treatment, i.e. cytoreductive surgery integrated with platinum-based chemotherapy, the rate of disease recurrence is very high and the available treatment options for recurrent disease are not curative. Thus, there is a need for more effective treatment options for ovarian cancer. Targeted drug conjugate systems have emerged as a promising therapeutic strategy for the treatment of ovarian cancer. These systems provide the opportunity to selectively deliver highly potent chemotherapeutic drugs to ovarian cancer, sparing healthy normal cells. Thus, the effectiveness of the drugs is improved and systemic toxicity is greatly reduced. In this review, different targeted drug conjugate systems that have been or are being developed for the treatment of ovarian cancer will be discussed.

Cell Surface Labeling and Detection of Protein Tyrosine Kinase 7 via Covalent Aptamers

Covalent aptamers are novel biochemical tools for fast and selective transfer of labels to target proteins. Equipped with cleavable electrophiles, these nucleic acid probes enable the installation of functional handles onto native proteins. The high affinity and specificity with which aptamers bind their selected targets allows for quick, covalent labeling that can compete with nuclease-mediated degradation. Here, we introduce the first application of covalent aptamers to modify a specific cell surface protein through proximity-driven label transfer. We targeted protein tyrosine kinase 7 (PTK7), a prominent cancer marker, and demonstrated aptamer-mediated biotin transfer to specific lysine residues on the extracellular domain of the protein. This allowed for tracking of PTK7 expression, localization, and cellular internalization. These studies validate the programmability of covalent aptamers and highlight their applicability in a cellular context, including protein and small molecule delivery.

Antibody-Drug Conjugates for Breast Cancer Treatment: Emerging Agents, Targets and Future Directions

To achieve the scheme of "magic bullets" in antitumor therapy, antibody-drug conjugates (ADCs) were developed. ADCs consist of antibodies targeting tumor-specific antigens, chemical linkers, and cytotoxic payloads that powerfully kill cancer cells. With the approval of ado-trastuzumab emtansine (T-DM1) and fam-trastuzumab deruxtecan (T-DXd), the therapeutic potentials of ADCs in breast cancer have come into the spotlight. Nearly 30 ADCs for breast cancer are under exploration to move targeted therapy forward. In this review, we summarize the presenting and emerging agents and targets of ADCs. The ADC structure and development history are also concluded. Moreover, the challenges faced and prospected future directions in this field are reviewed, which give insights into novel treatments with ADCs for breast cancer.

Antibody-drug conjugates: the evolving field of targeted chemotherapy for breast cancer treatment

Antibody-drug conjugates (ADCs) are a class of antineoplastic agents whose structure is composed of three main components: a monoclonal antibody (mAB) targeting a specific target antigen, a cytotoxic payload, and a linker binding the antibody to the payload. By combining the specificity of mABs with the high potency of the payloads, ADCs constitute a smart drug delivery system with improved therapeutic index. After recognition and binding of the mAB to its target surface antigen, ADCs are internalized by endocytosis by the tumor cell, releasing the payloads into the cytoplasm, where they exert their cytotoxic activity, eventually leading to cell death. The composition of some of the new ADCs confers additional functional properties that allow expanding their activity to neighboring cells not expressing the target antigen, constituting a valuable strategy to overcome tumor heterogeneity. Some of these 'off-target effects', such as the bystander effect, are possibly the mechanism underlying the antitumor activity demonstrated in patients with low expression of the target antigens, which represents an important paradigm shift in anticancer targeted therapy. Three ADCs are currently approved for the treatment of breast cancer (BC); two anti-HER2 (human epidermal growth factor receptor 2) ADCs (trastuzumab emtansine and trastuzumab deruxtecan); and one Trop-2-targeted ADC (sacituzumab govitecan). Based on the unprecedented efficacy data demonstrated by these agents, ADCs have been incorporated as part of standard regimens for all subtypes of advanced BC, as well as for high-risk early HER2-positive BC. Despite the remarkable advances, several hurdles still remain to overcome, including the development of reliable biomarkers for patient selection, prevention, and management of potentially severe toxicities, ADC resistance mechanisms, post-ADC resistance patterns, and optimal treatment sequencing and combinations. In this review, we will summarize the currently available evidence related to the use of these agents, as well as explore the current landscape of ADC development for BC treatment.

A novel TREM1/DAP12-based multiple chain CAR-T cell targets PTK7 in ovarian cancer therapy

While CAR-T cell therapy has shown success against hematological tumors, its effectiveness for solid tumors, including ovarian cancer, remains unsatisfactory. This study aimed to develop and evaluate the efficacy of novel chimeric antigen receptor T (CAR-T) cells targeting PTK7 through TREM1/DAP12 signaling against ovarian cancer. The expression of PTK7 in ovarian cancer tissues and cells was evaluated using immunohistochemical staining and flow cytometric analysis. The anti-tumor effects of PTK7 CAR-T cells were assessed in vitro using real-time cell analysis and enzyme-linked immunosorbent assay, and in vivo using a xenograft tumor model. PTK7 was significantly expressed in ovarian cancer tissues and cells. PTK7-targeting CAR-T cells based on TREM1/DAP12 signaling exhibited potent cytotoxicity against ovarian cancer cells expressing PTK7 in vitro, and effectively eradicated tumors in vivo. Our findings suggest that TREM1/DAP12-based PTK7 CAR-T cells have potential as a treatment strategy for ovarian cancer. Further studies are needed to evaluate the safety and efficacy of this approach in clinical trials.

What to do after immune-checkpoint inhibitors failure in advanced non-small cell lung cancer: an expert opinion and review

INTRODUCTION

Immune-checkpoint inhibitors (IO) have significantly improved outcomes of patients with non-oncogene-addicted non-small cell lung cancer (NSCLC), becoming the first-line agents for advanced disease. However, resistance remains a significant clinical challenge, limiting their effectiveness.

AREAS COVERED

Hereby, we addressed standard and innovative therapeutic approaches for NSCLC patients experiencing progression after IO treatment, discussing the emerging resistance mechanisms and the ongoing efforts to overcome them. In order to provide a complete overview of the matter, we performed a comprehensive literature search across prominent databases, including PubMed, EMBASE (Excerpta Medica dataBASE), and the Cochrane Library, and a research of the main ongoing studies on clinicaltrials.gov.

EXPERT OPINION

The dynamics of progression to IO, especially in terms of time to treatment failure and burden of progressive disease, should guide the best subsequent management, together with patient clinical conditions. Long-responders to IO might benefit from continuation of IO beyond-progression, in combination with other treatments. Patients who experience early progression should be treated with salvage CT in case of preserved clinical conditions. Finally, patients who respond to IO for a considerable timeframe and who later present oligo-progression could be treated with a multimodal approach in order to maximize the benefit of immunotherapy.

A sensitive LC-MS/MS assay to quantitate free payload Aur0101 from ADC PYX-201 in rat and monkey plasma

Aim: Aur0101 is a cytotoxic and small-molecule microtubule depolymerizing agent, and is the payload conjugated to antibody-drug conjugate PYX-201. Developing and validating a sensitive bioanalytical method to quantitate Aur0101 was novel and crucial in preclinical PYX-201 studies. Materials & methods: Reference standard Aur0101 and its stable isotope labelled internal standard Aur0101-d8 were used in this LC-MS/MS method. Results: This sensitive assay was validated at a lower limit of quantitation of 15 pg/ml and successfully applied to support preclinical rat and monkey toxicology studies. Preclinical plasma toxicokinetic parameters were presented. Conclusion: A sensitive and robust LC-MS/MS assay was validated for Aur0101 in rat and monkey plasma.

Identification and targeting of protein tyrosine kinase 7 (PTK7) as an immunotherapy candidate for neuroblastoma

GD2-targeting immunotherapies have improved survival in children with neuroblastoma, yet on-target, off-tumor toxicities can occur and a subset of patients cease to respond. The majority of neuroblastoma patients who receive immunotherapy have been previously treated with cytotoxic chemotherapy, making it paramount to identify neuroblastoma-specific antigens that remain stable throughout standard treatment. Cell surface glycoproteomics performed on human-derived neuroblastoma tumors in mice following chemotherapy treatment identified protein tyrosine kinase 7 (PTK7) to be abundantly expressed. Furthermore, PTK7 shows minimal expression on pediatric-specific normal tissues. We developed an anti-PTK7 chimeric antigen receptor (CAR) and find PTK7 CAR T cells specifically target and kill PTK7-expressing neuroblastoma in vitro. In vivo, human/murine binding PTK7 CAR T cells regress aggressive neuroblastoma metastatic mouse models and prolong survival with no toxicity. Together, these data demonstrate preclinical efficacy and tolerability for targeting PTK7 and support ongoing investigations to optimize PTK7-targeting CAR T cells for neuroblastoma.

Arising Novel Agents in Lung Cancer: Are Bispecifics and ADCs the New Paradigm?

Lung cancer is one of the most common cancers with the highest mortality. Non-small cell lung cancer (NSCLC) contributes to around 85% of lung cancer diagnoses (vs. 15% for small cell lung cancer). The treatment of NSCLC has vastly changed in the last two decades since the development of immunotherapy and targeted therapy against driver mutations. As is the nature of malignancy, cancer cells have acquired resistance to these treatments prompting an investigation into novel treatments and new targets. Bispecific antibodies, capable of targeting multiple substrates at once, and antibody-drug conjugates that can preferentially deliver chemotherapy to tumor cells are examples of this innovation. From our initial evaluation, both treatment modalities appear promising.

Antibody-Drug Conjugates in Lung Cancer: Recent Advances and Implementing Strategies

Antibody-drug conjugates (ADCs) are one of the fastest-growing oncology therapeutics, merging the cytotoxic effect of conjugated payload with the high specific ability and selectivity of monoclonal antibody targeted on a specific cancer cell membrane antigen. The main targets for ADC development are antigens commonly expressed by lung cancer cells, but not in normal tissues. They include human epidermal growth factor receptor 2, human epidermal growth factor receptor 3, trophoblast cell surface antigen 2, c-MET, carcinoembryonic antigen-related cell adhesion molecule 5, and B7-H3, each with one or more specific ADCs that showed encouraging results in the lung cancer field, more in non-small-cell lung cancer than in small-cell lung cancer histology. To date, multiple ADCs are under evaluation, alone or in combination with different molecules (eg, chemotherapy agents or immune checkpoint inhibitors), and the optimal strategy for selecting patients who may benefit from the treatment is evolving, including an improvement of biomarker understanding, involving markers of resistance or response to the payload, besides the antibody target. In this review, we discuss the available evidence and future perspectives on ADCs for lung cancer treatment, including a comprehensive discussion on structure-based drug design, mechanism of action, and resistance concepts. Data were summarized by specific target antigen, biology, efficacy, and safety, differing among ADCs according to the ADC payload and their pharmacokinetics and pharmacodynamics properties.

Resistance to antibody-drug conjugates in breast cancer: mechanisms and solutions

Antibody-drug conjugates (ADCs) are a rapidly developing therapeutic approach in cancer treatment that has shown remarkable activity in breast cancer. Currently, there are two ADCs approved for the treatment of human epidermal growth factor receptor 2-positive breast cancer, one for triple-negative breast cancer, and multiple investigational ADCs in clinical trials. However, drug resistance has been noticed in clinical use, especially in trastuzumab emtansine. Here, the mechanisms of ADC resistance are summarized into four categories: antibody-mediated resistance, impaired drug trafficking, disrupted lysosomal function, and payload-related resistance. To overcome or prevent resistance to ADCs, innovative development strategies and combination therapy options are being investigated. Analyzing predictive biomarkers for optimal therapy selection may also help to prevent drug resistance.

CAR-Based Immunotherapy of Solid Tumours-A Survey of the Emerging Targets

Immunotherapy with CAR T-cells has revolutionised the treatment of B-cell and plasma cell-derived cancers. However, solid tumours present a much greater challenge for treatment using CAR-engineered immune cells. In a partner review, we have surveyed data generated in clinical trials in which patients with solid tumours that expressed any of 30 discrete targets were treated with CAR-based immunotherapy. That exercise confirms that efficacy of this approach falls well behind that seen in haematological malignancies, while significant toxic events have also been reported. Here, we consider approximately 60 additional candidates for which such clinical data are not available yet, but where pre-clinical data have provided support for their advancement to clinical evaluation as CAR target antigens.

Advances in antibody-drug conjugates for gynecologic malignancies

PURPOSE OF REVIEW

Antibody-drug conjugates (ADCs) represent a new class of drugs that combine a surface receptor-targeting antibody linked to a cytotoxic molecule delivering the potent cytotoxic payload directly to tumor cells. This review summarizes the current literature demonstrating their use in the treatment of gynecologic malignancies.

RECENT FINDINGS

Tisotumab vedotin is the first U.S. Food and Drug Administration (FDA) approved ADC for the treatment of gynecologic cancers. While in the phase 3 randomized controlled trial in platinum resistant ovarian cancer patients, FORWARD 1, mirvetuximab did not meet its primary endpoint of progression-free survival. But we await more recent data from the two ongoing phase 3 trials of mirvetuximab in recurrent ovarian cancer patients. HER2/neu, Napi2b, mesothelin, and human trophoblast cell-surface marker (Trop-2) overexpression have also been exploited as excellent targets by novel ADCs in multiple tumors including ovarian, endometrial, and cervical cancers.

SUMMARY

Current evidence strongly supports the use of ADCs and ongoing clinical trials will provide further information into the potential of making these drugs part of current standard practice allowing patients to be treated with a higher level of personalized cancer care.

A review of recent advances on single use of antibody-drug conjugates or combination with tumor immunology therapy for gynecologic cancer

Immune checkpoint inhibitors have made significant progress in the treatment of various cancers. However, due to the low ICI responsive rate for the gynecologic cancer, ICI two-drug combination therapy tends to be a predominant way for clinical treatment. Antibody-drug conjugates, a promising therapeutic modality for cancer, have been approved by the FDA for breast cancer, lymphoma, multiple myeloma and gastric cancer. On September 2021, the FDA granted accelerated approval to tisotumab vedotin for patients with recurrent or metastatic cervical cancer. Currently, the role of therapy of ADCs on gynecologic tumors was also included in medication regimens. Now more than 30 ADCs targeting for 20 biomarkers are under clinical trials in the field, including monotherapy or combination with others for multiple lines of therapy. Some ADCs have been proved to enhance the antitumor immunity effect on both pre-clinical models and clinical trials. Therefore, combination of ADCs and ICIs are expected in clinical trials. In this review, we discuss current development of ADCs in gynecologic oncology and the combination effects of ICIs and ADCs.

Antibody drug conjugates: The dos and don'ts in clinical development

Antibody Drug Conjugates (ADCs) entered clinical trials in the mid 1990s to selectively deliver cytotoxic chemotherapy to cancer cells with the goal to increase the antitumor activity and decrease normal tissue toxicity. Over nearly 30 years of development the ADC platform has become established with now 11 approved agents and many more in the pipeline. This review is designed to highlight some of the problems and solutions encountered in clinical development as well as provide practical instruction to both clinical investigators on the efficient protocol design for ADCs and the lessons learned.

Anti-PTK7 Monoclonal Antibodies Inhibit Angiogenesis by Suppressing PTK7 Function

Simple Summary

PTK7 is a catalytically defective receptor protein tyrosine kinase. We previously demonstrated that PTK7 enhances angiogenesis by interacting with KDR, a vascular endothelial growth factor (VEGF) receptor important for angiogenesis, and activating it through oligomerization. To control angiogenesis by inhibiting PTK7 function, we developed anti-PTK7 monoclonal antibodies (mAbs). The selected PTK7 mAbs reduced VEGF-induced angiogenic phenotypes of endothelial cells and angiogenesis ex vivo and in vivo. The PTK7 mAbs also inhibited VEGF-induced KDR activation in endothelial cells and its downstream signaling and PTK7–KDR interaction. Our results show that the PTK7 mAbs inhibit angiogenesis by blocking PTK7 function. Therefore, PTK7 mAbs could be applied as therapeutics to control angiogenesis-associated diseases such as metastatic cancers.

Abstract

PTK7, a catalytically defective receptor protein tyrosine kinase, promotes angiogenesis by activating KDR through direct interaction and induction of KDR oligomerization. This study developed anti-PTK7 monoclonal antibodies (mAbs) to regulate angiogenesis by inhibiting PTK7 function. The effect of anti-PTK7 mAbs on vascular endothelial growth factor (VEGF)-induced angiogenic phenotypes in human umbilical vascular endothelial cells (HUVECs) was examined. Analysis of mAb binding with PTK7 deletion mutants revealed that mAb-43 and mAb-52 recognize immunoglobulin (Ig) domain 2 of PTK7, whereas mAb-32 and mAb-50 recognize Ig domains 6–7. Anti-PTK7 mAbs inhibited VEGF-induced adhesion and wound healing in HUVECs. mAb-32, mAb-43, and mAb-52 dose-dependently mitigated VEGF-induced migration and invasion in HUVECs without exerting cytotoxic effects. Additionally, mAb-32, mAb-43, and mAb-52 inhibited capillary-like tube formation in HUVECs, and mAb-32 and mAb-43 suppressed angiogenesis ex vivo (aortic ring assay) and in vivo (Matrigel plug assay). Furthermore, mAb-32 and mAb-43 downregulated VEGF-induced KDR activation and downstream signaling and inhibited PTK7–KDR interaction in PTK7-overexpressing and KDR-overexpressing HEK293 cells. Thus, anti-PTK7 mAbs inhibit angiogenic phenotypes by blocking PTK7–KDR interaction. These findings indicate that anti-PTK7 mAbs that neutralize PTK7 function can alleviate impaired angiogenesis-associated pathological conditions, such as cancer metastasis.

Icariin attenuates the tumor growth by targeting miR-1-3p/TNKS2/Wnt/β-catenin signaling axis in ovarian cancer

Purpose

Despite various therapy advances, ovarian cancer remains an incurable disease for which survival rates have only modestly improved. Natural products are important sources of anti-cancer lead compounds. Icariin exhibited broad anti-cancer efficacy. However, the mechanism of icariin against ovarian cancer is poorly elucidated.

Methods

Cell viability was detected to evaluate the effect of icariin on SKOV-3 cells. The cell cycle and apoptosis were analyzed. The transcript of SKOV-3 cells was profiled by RNA-seq. GSEA and DEGs analyses were performed to interpret gene expression data. Western blot and TOP/FOP flash assay were applied to detect Wnt/β-catenin signaling. MiRDB database and dual-luciferase reporter assay was applied to study the regulation of miR-1-3p on TNKS2. Anti-tumor efficacy of icariin was evaluated by xenograft mouse model. Immunohistochemistry was performed with antibodies against Ki67.

Results

Icariin significantly suppressed the proliferation of SKOV-3 cells. Furthermore, icariin stalled cell cycle and induced apoptosis by blocking TNKS2/Wnt/β-catenin pathway through upregulating the level of miR-1-3p. Finally, icariin dramatically suppressed tumor growth in vivo.

Conclusions

In this study, we demonstrated for the first time that icariin significantly attenuated the growth of ovarian tumor in xenograft mouse model. Furthermore, we systematically revealed that icariin attenuates the tumor progression by suppressing TNKS2/Wnt/β-catenin signaling via upregulating the level of miR-1-3p in ovarian cancer with transcriptome analysis.

Recent advances in therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer (BC) with a poor prognosis. Current treatment options are limited to surgery, adjuvant chemotherapy and radiotherapy; however, a proportion of patients have missed the surgical window at the time of diagnosis. TNBC is a highly heterogeneous cancer with specific mutations and aberrant activation of signaling pathways. Hence, targeted therapies, such as those targeting DNA repair pathways, androgen receptor signaling pathways, and kinases, represent promising treatment options against TNBC. In addition, immunotherapy has also been demonstrated to improve overall survival and response in TNBC. In this review, we summarize recent key advances in therapeutic strategies based on molecular subtypes in TNBC.

Multiomics characterization implicates PTK7 in ovarian cancer EMT and cell plasticity and offers strategies for therapeutic intervention

Most patients with ovarian cancer (OC) are diagnosed at a late stage when there are very few therapeutic options and a poor prognosis. This is due to the lack of clearly defined underlying mechanisms or an oncogenic addiction that can be targeted pharmacologically, unlike other types of cancer. Here, we identified protein tyrosine kinase 7 (PTK7) as a potential new therapeutic target in OC following a multiomics approach using genetic and pharmacological interventions. We performed proteomics analyses upon PTK7 knockdown in OC cells and identified novel downstream effectors such as synuclein-γ (SNCG), SALL2, and PP1γ, and these findings were corroborated in ex vivo primary samples using PTK7 monoclonal antibody cofetuzumab. Our phosphoproteomics analyses demonstrated that PTK7 modulates cell adhesion and Rho-GTPase signaling to sustain epithelial-mesenchymal transition (EMT) and cell plasticity, which was confirmed by high-content image analysis of 3D models. Furthermore, using high-throughput drug sensitivity testing (525 drugs) we show that targeting PTK7 exhibited synergistic activity with chemotherapeutic agent paclitaxel, CHK1/2 inhibitor prexasertib, and PLK1 inhibitor GSK461364, among others, in OC cells and ex vivo primary samples. Taken together, our study provides unique insight into the function of PTK7, which helps to define its role in mediating aberrant Wnt signaling in ovarian cancer.

Antibody-Drug Conjugates Containing Payloads from Marine Origin

Antibody-drug conjugates (ADCs) are an important class of therapeutics for the treatment of cancer. Structurally, an ADC comprises an antibody, which serves as the delivery system, a payload drug that is a potent cytotoxin that kills cancer cells, and a chemical linker that connects the payload with the antibody. Unlike conventional chemotherapy methods, an ADC couples the selective targeting and pharmacokinetic characteristics related to the antibody with the potent cytotoxicity of the payload. This results in high specificity and potency by reducing off-target toxicities in patients by limiting the exposure of healthy tissues to the cytotoxic drug. As a consequence of these outstanding features, significant research efforts have been devoted to the design, synthesis, and development of ADCs, and several ADCs have been approved for clinical use. The ADC field not only relies upon biology and biochemistry (antibody) but also upon organic chemistry (linker and payload). In the latter, total synthesis of natural and designed cytotoxic compounds, together with the development of novel synthetic strategies, have been key aspects of the consecution of clinical ADCs. In the case of payloads from marine origin, impressive structural architectures and biological properties are observed, thus making them prime targets for chemical synthesis and the development of ADCs. In this review, we explore the molecular and biological diversity of ADCs, with particular emphasis on those containing marine cytotoxic drugs as the payload.

[Current Progress and Future Developments of Antibody Drug Conjugates in Lung Cancer]

Antibody drug conjugates (ADCs) are a novel class of anti-cancer drugs, which combined the specificity of monoclonal antibodies with the cytotoxic palyload via the linkers. Many ADCs have not only verified impressive activity in a variety of cancers, including breast cancer and hematological system tumors, but also in lung cancer. The aim of this study was to provide informations for practice by summarizing the mechanism of action, clinical application and problems and challenges of ADCs.
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Joint Disposition Properties and Comprehensive Pharmacokinetic Characterization of Antibody–Drug Conjugates

Antibody–drug conjugates (ADCs) comprise 3 distinct parts: a specific antibody carrier (mAb), a linker, and a cytotoxic payload. Typical pharmacokinetic (PK) characterization of ADCs remains fragmented using separate noncompartmental analyses (NCA) of individual analytes, offering little insight into the dynamic relationships among the ADC components, and the safety and efficacy implications. As a result, it is exceedingly difficult to compare ADCs in terms of favorable PK characteristics. Therefore, there is a need for characterizing ADCs using the joint disposition properties critical for understanding the fate of an ADC complex and clinical implications. In this communication, we describe 3 joint disposition metrics (JDMs) for integrated NCA of ADCs based on a combination of common analytes of ADC, payload, conjugated payload, and total mAb. These JDMs were derived, each in a simple form of a ratio between appropriate PK parameters of two analytes, from the presumed drug delivery scheme behind typical ADC designs, in terms of (1) linker stability, (2) therapeutic exposure ratio, and (3) effective drug-to-antibody ratio in vivo. The validity of the JDM-based PK characterization was examined against model-based analyses via their applications to 3 clinical candidates: PF-06650808, PF-06647020, and PF-06664178. For instance, the linker stability estimates for PF-06650808, PF-06647020, and PF-06664178 were 0.31, 0.14, and 0.096, respectively, from the JDM-based analyses vs. 0.23, 0.11, and 0.086 by the model-based approach. Additionally, the JDMs were estimated for a number of FDA-approved or otherwise well-documented ADCs, showing their utilities in comparing ADCs in terms of favorable PK characteristics.

Graphical Abstract

Discovery and Development of Dolastatin 10-Derived Antibody Drug Conjugate Anticancer Drugs

Dolastatin 10 is an extremely potent broad-spectrum antitubulin anticancer pentapeptide isolated from Dolabella auricularia. The two-dimensional structure was elucidated by NMR and mass spectrometric analyses. The absolute configuration was determined by a convergent total synthesis. SAR studies established that modifications at C- and N-terminals were tolerated for cytotoxic activity. Human clinical trials of dolastatin 10 and auristatin PE (a C-terminal analog) showed occasional signs of efficacy but failed due to lack of separation of toxicity and efficacy. Nanomolar cytotoxicity helped transition this class of pentapeptides to the next phase of development as antibody drug conjugates (ADCs) by reducing systemic toxicity. Four ADC drugs (Adcetris, Padcev, Polivy, and Blenrep) carrying monomethyl auristatin E (MMAE, vedotin) and monomethyl auristatin F (MMAF, mafodotin) payloads have been approved for treatment of a number of cancers expressing antibody-specific antigens. More than 36 ADCs carrying a variety of pentapeptide analogues are undergoing preclinical and clinical developments. They are being evaluated in more than 200 human trials. A comprehensive review of the discovery, total synthesis of dolastatin 10 and new amino acids, SAR studies of dolastatin 10 and auristatins, conjugations to antibodies, and preclinical and clinical development of ADCs have been presented.

[Research Progress of Antibody-drug Conjugates in Advanced Non-small Cell Lung Cancer]

Lung cancer is one of the malignant tumors with the highest morbidity and mortality in the world. Non-small cell lung cancer (NSCLC) is one of the most important pathological types of lung cancer. The prognosis of advanced NSCLC is poor and medical treatment is still the main treatment option. Antibody-drug conjugates (ADCs) are the kind of potentially new anti-tumor drugs, consisting of monoclonal antibodies conjugated to the cytotoxic payloads via the synthetic linkers. They have a broad application prospect in solid tumors such as lung cancer. This article focuses on the mechanism of action and research progress of ADCs in advanced NSCLC.
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In Vivo Evaluation of Sgc8-c Aptamer as a Molecular Imaging Probe for Colon Cancer in a Mouse Xenograft Model

Recent biotechnological applications in the field of clinical oncology led to the identification of new biomarkers as molecular targets of cancer, and to broad developments in the field of personalized medicine. Aptamers are oligonucleotides (ssDNA or RNA) that are selected to specifically recognize a molecular target with high affinity and specificity. Based on this, new horizons for their use as molecular imaging probes are being explored. The objective of this work was to evaluate the Sgc8-c aptamer conjugated with Alexa Fluor 647 fluorophore as an imaging probe in a colon tumor xenograft mouse model, with potential application in molecular imaging. In this study, the LS174T cell line was used to induce colorectal adenocarcinoma in nude mice. After confirmation of PTK7 overexpression by immunohistochemistry, in vivo studies were performed. Pharmacokinetic, in vivo and ex vivo biodistribution imaging, and a competition assay were evaluated by fluorescence imaging. In vivo visualization of the probe in the tumors was assessed two hours after aptamer probe administration, exhibiting excellent tumor-to-background ratios in biodistribution studies and high specificity in the competition test. Our results demonstrated the functionality of Scg8-c as an imaging probe for colon cancer, with potential clinical applications.

Future Directions for the Discovery of Natural Product-Derived Immunomodulating Drugs

Drug discovery from natural sources is going through a renaissance, having spent many decades in the shadow of synthetic molecule drug discovery, despite the fact that natural product-derived compounds occupy a much greater chemical space than those created through synthetic chemistry methods. With this new era comes new possibilities, not least the novel targets that have emerged in recent times and the development of state-of-the-art technologies that can be applied to drug discovery from natural sources. Although progress has been made with some immunomodulating drugs, there remains a pressing need for new agents that can be used to treat the wide variety of conditions that arise from disruption, or over-activation, of the immune system; natural products may therefore be key in filling this gap. Recognising that, at present, there is no authoritative article that details the current state-of-the-art of the immunomodulatory activity of natural products, this in-depth review has arisen from a joint effort between the International Union of Basic and Clinical Pharmacology (IUPHAR) Natural Products and Immunopharmacology, with contributions from a Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation number of world-leading researchers in the field of natural product drug discovery, to provide a "position statement" on what natural products has to offer in the search for new immunomodulatory argents. To this end, we provide a historical look at previous discoveries of naturally occurring immunomodulators, present a picture of the current status of the field and provide insight into the future opportunities and challenges for the discovery of new drugs to treat immune-related diseases.

Antibody-drug conjugates: Resurgent anticancer agents with multi-targeted therapeutic potential

Antibody-drug conjugates (ADCs) constitute a relatively new group of anticancer agents, whose first appearance took place about two decades ago, but a renewed interest occurred in recent years, following the success of anti-cancer immunotherapy with monoclonal antibodies. Indeed, an ADC combines the selectivity of a monoclonal antibody with the cell killing properties of a chemotherapeutic agent (payload), joined together through an appropriate linker. The antibody moiety targets a specific cell surface antigen expressed by tumor cells and/or cells of the tumor microenvironment and acts as a carrier that delivers the cytotoxic payload within the tumor mass. Despite advantages in terms of selectivity and potency, the development of ADCs is not devoid of challenges, due to: i) low tumor selectivity when the target antigens are not exclusively expressed by cancer cells; ii) premature release of the cytotoxic drug into the bloodstream as a consequence of linker instability; iii) development of tumor resistance mechanisms to the payload. All these factors may result in lack of efficacy and/or in no safety improvement compared to unconjugated cytotoxic agents. Nevertheless, the development of antibodies engineered to remain inert until activated in the tumor (e.g., antibodies activated proteolytically after internalization or by the acidic conditions of the tumor microenvironment) together with the discovery of innovative targets and cytotoxic or immunomodulatory payloads, have allowed the design of next-generation ADCs that are expected to possess improved therapeutic properties. This review provides an overview of approved ADCs, with related advantages and limitations, and of novel targets exploited by ADCs that are presently under clinical investigation.

Antibody drug conjugates in non-small cell lung cancer: An emerging therapeutic approach

The current standard-of-care for the treatment of advanced non-small cell lung cancer (NSCLC) incorporates targeted therapies, immune-checkpoint inhibitors (ICI) and systemic chemotherapy. Antibody-drug conjugates (ADC) are a class of anti-cancer therapy capable of transporting cytotoxic drugs directly to tumour cells, thus harnessing the strengths of both cytotoxic chemotherapy and targeted therapy. In this review we provide a comprehensive review the design, mode of action, and mechanisms of resistance to ADCs in NSCLC. We also summarize the clinical development of several promising ADCs in early phase clinical trials for the treatment NSCLC. including ADCs against well-established targets (e.g.HER2 in breast cancer, Nectin4 in urothelial cancer), novel antigenic targets (e.g. HER3, TROP2, PTK7, CEACAM5), as well as promising combinations with agents known to be active in NSCLC such as tyrosine kinase inhibitors and ICI therapy, as a strategy to overcome mechanisms of resistance to ADC therapy.

Molecular targets and therapeutics in chemoresistance of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a specific subtype of breast cancer (BC), which shows immunohistochemically negative expression of hormone receptor i.e., Estrogen receptor and Progesterone receptor along with the absence of Human Epidermal Growth Factor Receptor-2 (HER2/neu). In Indian scenario the prevalence of BC is 26.3%, whereas, in West Bengal the cases are of 18.4%. But the rate of TNBC has increased up to 31% and shows 27% of total BC. Conventional chemotherapy is effective only in the initial stages but with progression of the disease the effectivity gets reduced and shown almost no effect in later or advanced stages of TNBC. Thus, TNBC patients frequently develop resistance and metastasis, due to its peculiar triple-negative nature most of the hormonal therapies also fails. Development of chemoresistance may involve various factors, such as, TNBC heterogeneity, cancer stem cells (CSCs), signaling pathway deregulation, DNA repair mechanism, hypoxia, and other molecular factors. To overcome the challenges to treat TNBC various targets and molecules have been exploited including CSCs modulator, drug efflux transporters, hypoxic factors, apoptotic proteins, and regulatory signaling pathways. Moreover, to improve the targets and efficacy of treatments researchers are emphasizing on targeted therapy for TNBC. In this review, an effort has been made to focus on phenotypic and molecular variations in TNBC along with the role of conventional as well as newly identified pathways and strategies to overcome challenge of chemoresistance.

Immunotherapy in Breast Cancer: When, How, and What Challenges?

Breast Cancer (BC) is the second most frequent cause of cancer death among women worldwide and, although there have been significant advances in BC therapies, a significant percentage of patients develop metastasis and disease recurrence. Since BC was demonstrated to be an immunogenic tumor, immunotherapy has broken through as a significant therapy strategy against BC. Over the years, immunotherapy has improved the survival rate of HER2+ BC patients due to the approval of some monoclonal antibodies (mAbs) such as Trastuzumab, Pertuzumab and, recently, Margetuximab, along with the antibody-drug conjugates (ADC) Trastuzumab-Emtansine (T-DM1) and Trastuzumab Deruxtecan. Immune checkpoint inhibitors (ICI) showed promising efficacy in triple-negative breast cancer (TNBC) treatment, namely Atezolizumab and Pembrolizumab. Despite the success of immunotherapy, some patients do not respond to immunotherapy or those who respond to the treatment relapse or progress. The main causes of these adverse events are the complex, intrinsic or extrinsic resistance mechanisms. In this review, we address the different immunotherapy approaches approved for BC and some of the mechanisms responsible for resistance to immunotherapy.

Antibody-Antineoplastic Conjugates in Gynecological Malignancies: Current Status and Future Perspectives

In the last decade, antibody-drug conjugates (ADCs), normally formed by a humanized antibody and a small drug via a chemical cleavable or non-cleavable linker, have emerged as a potential treatment strategy in cancer disease. They allow to get a selective delivery of the chemotherapeutic agents at the tumor level, and, consequently, to improve the antitumor efficacy and, especially to decrease chemotherapy-related toxicity. Currently, nine antibody-drug conjugate-based formulations have been already approved and more than 80 are under clinical trials for the treatment of several tumors, especially breast cancer, lymphomas, and multiple myeloma. To date, no ADCs have been approved for the treatment of gynecological formulations, but many formulations have been developed and have reached the clinical stage, especially for the treatment of ovarian cancer, an aggressive disease with a low five-year survival rate. This manuscript analyzes the ADCs formulations that are under clinical research in the treatment of gynecological carcinomas, specifically ovarian, endometrial, and cervical tumors.

Protein Tyrosine Kinase 7 Regulates EGFR/Akt Signaling Pathway and Correlates With Malignant Progression in Triple-Negative Breast Cancer

Purpose

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer, is associated with high invasiveness, high metastatic occurrence and poor prognosis. Protein tyrosine kinase 7 (PTK7) plays an important role in multiple cancers. However, the role of PTK7 in TNBC has not been well addressed. This study was performed to evaluate the role of PTK7 in the progression of TNBC.

Methods

Correlation of PTK7 expression with clinicopathological parameters was assessed using tissue microarray immunohistochemistry (IHC) staining in 280 patients with breast cancer. PTK7 expression in TNBC (MDA-MB-468, MDA-MB-436 and MDA-MB-231) and non-TNBC (MCF7 and SK-BR-3) breast cancer cell lines were examined using immunoblotting assay. PTK7 correlated genes in invasive breast carcinoma were analyzed using cBioPortal breast cancer datasets including 1,904 patients. PTK7 overexpressed or knockdown TNBC cell lines (MDA-MB-468 and MDA-MB-436) were used to analyze the potential roles of PTK7 in TNBC metastasis and tumor progression. A TNBC tumor bearing mouse model was established to further analyze the role of PTK7 in TNBC tumorigenicity in vivo.

Results

PTK7 is highly expressed in breast cancer and correlates with worse prognosis and associates with tumor metastasis and progression in TNBC. Co-expression analysis and gain- or loss-of-function of PTK7 in TNBC cell lines revealed that PTK7 participates in EGFR/Akt signaling regulation and associated with extracellular matrix organization and migration genes in breast cancer, including COL1A1, FN1, WNT5B, MMP11, MMP14 and SDC1. Gain- or loss-of-function experiments of PTK7 suggested that PTK7 promotes proliferation and migration in TNBC cell lines. PTK7 knockdown MDA-MB-468 cell bearing mouse model further demonstrated that PTK7-deficiency inhibits TNBC tumor progression in vivo.

Conclusion

This study identified PTK7 as a potential marker of worse prognosis in TNBC and revealed PTK7 promotes TNBC metastasis and progression via EGFR/Akt signaling pathway.