Anti-NaPi2b antibody-drug conjugate lifastuzumab vedotin (DNIB0600A) compared with pegylated liposomal doxorubicin in patients with platinum-resistant ovarian cancer in a randomized, open-label, phase II study

Selected markers of ovarian cancer and their relation to targeted therapy (Review)

Despite advances in surgical treatment techniques and chemotherapy-including anti-angiogenic and immune poly (ADP-ribose) polymerase inhibitors, the 5-year survival rate in ovarian cancer (OC) remains low. The reasons for this are the diagnosis of cancer in advanced clinical stages, chemoresistance and cancer recurrence. New therapeutic approaches are being developed, including the search for new biomarkers that are also targets for targeted therapy. The present review describes new molecular markers with relevance to targeted therapy, which to date have been studied only in experimental research. These include the angiogenic protein angiopoietin-2, the transmembrane glycoprotein ectonucleotide pyrophosphatase/phosphodiesterase 1, the adhesion protein E-cadherin, the TIMP metallopeptidase inhibitor 1 and Kruppel-like factor 7. Drugs affecting cancer stem cells (CSCs) in OC, such as metformin and salinomycin, as well as inhibitors of CSCs markers aldehyde dehydrogenase 1 (with the drug ATRA) and the transcription factor Nanog homeobox (microRNA) are also discussed. A new approach to prevention and possible therapies under investigation such as development of vaccines containing a subpopulation of CD117(+) and CD44(+) stem cells with a promising option for use in women with OC was described.

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.

Improving Intracellular Delivery of an Antibody-Drug Conjugate Targeting Carcinoembryonic Antigen Increases Efficacy at Clinically Relevant Doses In Vivo

Solid tumor antibody-drug conjugates (ADC) have experienced more clinical success in the last 5 years than the previous 18-year span since the first ADC approval in 2000. While recent advances in protein engineering, linker design, and payload variations have played a role in this success, high expression and readily internalized targets have also been crucial to solid tumor therapy. However, these factors are also paradoxically connected to poor tissue penetration and lower efficacy. Previous work shows that potent ADCs can benefit from slower internalization under subsaturating doses to improve tissue penetration and increase tumor response. In contrast, faster internalization is predicted to increase efficacy under higher, tumor saturating doses. In this work, the intracellular delivery of SN-38 conjugated to an anti-carcinoembryonic antigen (anti-CEA) antibody (Ab) is increased by coadministering a noncompeting (cross-linking) anti-CEA Ab to improve efficacy in a colorectal carcinoma animal model. The SN-38 payload enables broad tumor saturation with clinically-tolerable doses, and under these saturating conditions, using a second CEA receptor cross-linking Ab yields faster internalization, which increases tumor killing efficacy. Our spheroid results show indirect bystander killing can also occur, but the more efficient direct cell killing from targeted intracellular payload release drives a greater tumor response. These results provide a strategy to increase therapeutic effectiveness with improved intracellular delivery under tumor saturating doses with the potential to expand the ADC target repertoire.

Molecular Dynamics Simulation of an Iron(III) Binding Site on the Fc Domain of IgG1 Relevant for Visible Light-Induced Protein Fragmentation

Molecular dynamics simulations were employed to investigate the interaction between Fe(III) and an iron-binding site composed of THR259, ASP252, and GLU261 on the Fc domain of an IgG1. The goal was to provide microscopic mechanistic information for the photochemical, iron-dependent site-specific oxidative fragmentation of IgG1 at THR259 reported in our previous paper. The distance between Fe(III) and residues of interest as well as the binding pocket size was examined for both protonated and deprotonated THR259. The Fe(III) binding free energy (ΔG) was estimated by using an umbrella sampling approach. The pKa shift of the THR259 hydroxyl group caused by the presence of nearby Fe(III) was estimated based on a thermodynamic cycle. The simulation results show that Fe(III) resides inside the proposed binding pocket and profoundly changes the pocket configuration. The ΔG values indicate that the pocket possesses a strong binding affinity for Fe(III). Furthermore, Fe(III) profoundly lowers the pKa value of the THR259 hydroxyl group by 5.4 pKa units.

The ever-expanding landscape of antibody-drug conjugates (ADCs) in solid tumors: A systematic review

BACKGROUND

The advent of targeted therapies signaled novel avenues for more optimal oncological outcomes. Antibody-drug conjugates (ADCs) have risen as a cornerstone of the ever-expanding targeted therapy era. The purpose of this systematic review is to delineate the rapidly evolving clinical landscape of ADCs for solid tumors.

METHODS

A literature search was performed in Medline, Embase and Cochrane databases for phase II and III clinical trials. Outcomes of interest were the objective response rate, overall survival, progression-free survival and adverse events.

RESULTS

A total of 92 clinical trials (76 phase II and 16 phase III) evaluated the efficacy and safety of ADCs for a plethora of solid tumors. Out of the 30 investigated ADCs, 8 have received approval by regulatory organizations for solid tumors. Currently, 52 phase III clinical trials for ADCs are ongoing.

CONCLUSION

ADCs have shown promising results for several solid tumors and various cancer settings.

Characterizing the regulatory Fas (CD95) epitope critical for agonist antibody targeting and CAR-T bystander function in ovarian cancer

Receptor clustering is the most critical step to activate extrinsic apoptosis by death receptors belonging to the TNF superfamily. Although clinically unsuccessful, using agonist antibodies, the death receptors-5 remains extensively studied from a cancer therapeutics perspective. However, despite its regulatory role and elevated function in ovarian and other solid tumors, another tumor-enriched death receptor called Fas (CD95) remained undervalued in cancer immunotherapy until recently, when its role in off-target tumor killing by CAR-T therapies was imperative. By comprehensively analyzing structure studies in the context of the binding epitope of FasL and various preclinical Fas agonist antibodies, we characterize a highly significant patch of positively charged residue epitope (PPCR) in its cysteine-rich domain 2 of Fas. PPCR engagement is indispensable for superior Fas agonist signaling and CAR-T bystander function in ovarian tumor models. A single-point mutation in FasL or Fas that interferes with the PPCR engagement inhibited apoptotic signaling in tumor cells and T cells. Furthermore, considering that clinical and immunological features of the autoimmune lymphoproliferative syndrome (ALPS) are directly attributed to homozygous mutations in FasL, we reveal differential mechanistic details of FasL/Fas clustering at the PPCR interface compared to described ALPS mutations. As Fas-mediated bystander killing remains vital to the success of CAR-T therapies in tumors, our findings highlight the therapeutic analytical design for potentially effective Fas-targeting strategies using death agonism to improve cancer immunotherapy in ovarian and other solid tumors.

Understanding the promising role of antibody drug conjugates in breast and ovarian cancer

A nascent category of anticancer therapeutic drugs called antibody-drug conjugates (ADCs) relate selectivity of aimed therapy using chemotherapeutic medicines with high cytotoxic power. Progressive linker technology led to the advancement of more efficacious and safer treatments. It offers neoteric as well as encouraging therapeutic strategies for treating cancer. ADCs selectively administer a medication by targeting antigens which are abundantly articulated on the membrane surface of tumor cells. Tumor-specific antigens are differently expressed in breast and ovarian cancers and can be utilized to direct ADCs. Compared to conventional chemotherapeutic drugs, this approach enables optimal tumor targeting while minimizing systemic damage. A cleavable linker improves the ADCs because it allows the toxic payload to be distributed to nearby cells that do not express the target protein, operating on assorted tumors with dissimilar cell aggregation. Presently fifteen ADCs are being studied in breast and ovarian carcinoma preclinically, and assortment of few have already undergone promising early-phase clinical trial testing. Furthermore, Phase I and II studies are investigating a wide variety of ADCs, and preliminary findings are encouraging. An expanding sum of ADCs will probably become feasible therapeutic choices as solo agents or in conjunction with chemotherapeutic agents. This review accentuates the most recent preclinical findings, pharmacodynamics, and upcoming applications of ADCs in breast and ovarian carcinoma.

Treatment of Ovarian Cancer Beyond PARP Inhibition: Current and Future Options

Ovarian cancer is the leading cause of gynecological cancer death. Improved understanding of the biologic pathways and introduction of poly (ADP-ribose) polymerase inhibitors (PARPi) during the last decade have changed the treatment landscape. This has improved outcomes, but unfortunately half the women with ovarian cancer still succumb to the disease within 5 years of diagnosis. Pathways of resistance to PARPi and chemotherapy have been studied extensively, but there is an unmet need to overcome treatment failure and improve outcome. Major mechanisms of PARPi resistance include restoration of homologous recombination repair activity, alteration of PARP function, stabilization of the replication fork, drug efflux, and activation of alternate pathways. These resistant mechanisms can be targeted to sensitize the resistant ovarian cancer cells either by rechallenging with PARPi, overcoming resistance mechanism or bypassing resistance pathways. Augmenting the PARPi activity by combining it with other targets in the DNA damage response pathway, antiangiogenic agents and immune checkpoint inhibitors can potentially overcome the resistance mechanisms. Methods to bypass resistance include targeting non-cross-resistant pathways acting independent of homologous recombination repair (HRR), modulating tumour microenvironment, and enhancing drug delivery systems such as antibody drug conjugates. In this review, we will discuss the first-line management of ovarian cancer, resistance mechanisms and potential strategies to overcome these.

Value of Antibody Drug Conjugates for Gynecological Cancers: A Modern Appraisal Following Recent FDA Approvals

Antibody drug conjugates (ADCs) are a new class of targeted anti-cancer therapies that combine a monoclonal tumor surface receptor-targeting antibody with a highly cytotoxic molecule payload. They enable delivery of cytotoxic therapy more directly to tumor cells and minimize delivery to healthy tissues. This review summarizes the existing literature about ADC therapies approved for use in gynecologic malignancies, relevant preclinical studies, as well as ongoing clinical trials.

Antibody-drug conjugates come of age in oncology

Antibody-drug conjugates (ADCs) combine the specificity of monoclonal antibodies with the potency of highly cytotoxic agents, potentially reducing the severity of side effects by preferentially targeting their payload to the tumour site. ADCs are being increasingly used in combination with other agents, including as first-line cancer therapies. As the technology to produce these complex therapeutics has matured, many more ADCs have been approved or are in late-phase clinical trials. The diversification of antigenic targets as well as bioactive payloads is rapidly broadening the scope of tumour indications for ADCs. Moreover, novel vector protein formats as well as warheads targeting the tumour microenvironment are expected to improve the intratumour distribution or activation of ADCs, and consequently their anticancer activity for difficult-to-treat tumour types. However, toxicity remains a key issue in the development of these agents, and better understanding and management of ADC-related toxicities will be essential for further optimization. This Review provides a broad overview of the recent advances and challenges in ADC development for cancer treatment.

Pegylated liposomal doxorubicin for relapsed epithelial ovarian cancer

BACKGROUND

Cancer of ovarian, fallopian tube and peritoneal origin, referred to collectively as ovarian cancer, is the eighth most common cancer in women and is often diagnosed at an advanced stage. Women with relapsed epithelial ovarian cancer (EOC) are less well and have a limited life expectancy, therefore maintaining quality of life with effective symptom control is an important aim of treatment. However, the unwanted effects of chemotherapy agents may be severe, and optimal treatment regimens are unclear. Pegylated liposomal doxorubicin (PLD), which contains a cytotoxic drug called doxorubicin hydrochloride, is one of several treatment modalities that may be considered for treatment of relapsed EOCs. This is an update of the original Cochrane Review which was published in Issue 7, 2013.

OBJECTIVES

To evaluate the efficacy and safety of PLD, with or without other anti-cancer drugs, in women with relapsed high grade epithelial ovarian cancer (EOC).

SEARCH METHODS

We searched CENTRAL, MEDLINE (via Ovid) and Embase (via Ovid) from 1990 to January 2022. We also searched online registers of clinical trials, abstracts of scientific meetings and reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that evaluated PLD in women diagnosed with relapsed epithelial ovarian cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data to a pre-designed data collection form and assessed the risk of bias according to the Cochrane Handbook for Systematic Reviews of Interventions guidelines. Where possible, we pooled collected data in meta-analyses.

MAIN RESULTS

This is an update of a previous review with 12 additional studies, so this updated review includes a total of 26 RCTs with 8277 participants that evaluated the effects of PLD alone or in combination with other drugs in recurrent EOC: seven in platinum-sensitive disease (2872 participants); 11 in platinum-resistant disease (3246 participants); and eight that recruited individuals regardless of platinum sensitivity status (2079 participants). The certainty of the evidence was assessed for the three most clinically relevant comparisons out of eight comparisons identified in the included RCTs. Recurrent platinum-sensitive EOC PLD with conventional chemotherapy agent compared to alternative combination chemotherapy likely results in little to no difference in overall survival (OS) (hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.83 to 1.04; 5 studies, 2006 participants; moderate-certainty evidence) but likely increases progression-free survival (PFS) (HR 0.81, 95% CI 0.74 to 0.89; 5 studies, 2006 participants; moderate-certainty evidence). The combination may slightly improve quality of life at three months post-randomisation, measured using European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire C30 (mean difference 4.80, 95% CI 0.92 to 8.68; 1 study, 608 participants; low-certainty evidence), but this may not represent a clinically meaningful difference. PLD in combination with another chemotherapy agent compared to alternative combination chemotherapy likely results in little to no difference in the rate of overall severe adverse events (grade ≥ 3) (risk ratio (RR) 1.11, 95% CI 0.95 to 1.30; 2 studies, 834 participants; moderate-certainty evidence). PLD with chemotherapy likely increases anaemia (grade ≥ 3) (RR 1.37, 95% CI 1.02 to 1.85; 5 studies, 1961 participants; moderate-certainty evidence). The evidence is very uncertain about the effect of PLD with conventional chemotherapy on hand-foot syndrome (HFS)(grade ≥ 3) (RR 4.01, 95% CI 1.00 to 16.01; 2 studies, 1028 participants; very low-certainty evidence) and neurological events (grade ≥ 3) (RR 0.38, 95% CI 0.20 to 0.74; 4 studies, 1900 participants; very low-certainty evidence). Recurrent platinum-resistant EOC PLD alone compared to another conventional chemotherapy likely results in little to no difference in OS (HR 0.96, 95% CI 0.77 to 1.19; 6 studies, 1995 participants; moderate-certainty evidence). The evidence is very uncertain about the effect of PLD on PFS (HR 0.94, 95% CI 0.85 to 1.04; 4 studies, 1803 participants; very low-certainty evidence), overall severe adverse events (grade ≥ 3) (RR ranged from 0.61 to 0.97; 2 studies, 964 participants; very low-certainty evidence), anaemia (grade ≥ 3) (RR ranged from 0.19 to 0.82; 5 studies, 1968 participants; very low-certainty evidence), HFS (grade ≥ 3) (RR ranged from 15.19 to 109.15; 6 studies, 2184 participants; very low-certainty evidence), and the rate of neurological events (grade ≥ 3)(RR ranged from 0.08 to 3.09; 3 studies, 1222 participants; very low-certainty evidence). PLD with conventional chemotherapy compared to PLD alone likely results in little to no difference in OS (HR 0.92, 95% CI 0.70 to 1.21; 1 study, 242 participants; moderate-certainty evidence) and it may result in little to no difference in PFS (HR 0.94, 95% CI 0.73 to 1.22; 2 studies, 353 participants; low-certainty evidence). The combination likely increases overall severe adverse events (grade ≥ 3) (RR 2.48, 95% CI 1.98 to 3.09; 1 study, 663 participants; moderate-certainty evidence) and anaemia (grade ≥ 3) (RR 2.38, 95% CI 1.46 to 3.87; 2 studies, 785 participants; moderate-certainty evidence), but likely results in a large reduction in HFS (grade ≥ 3) (RR 0.24, 95% CI 0.14 to 0.40; 2 studies, 785 participants; moderate-certainty evidence). It may result in little to no difference in neurological events (grade ≥ 3) (RR 1.40, 95% CI 0.85 to 2.31; 1 study, 663 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

In platinum-sensitive relapsed EOC, including PLD in a combination chemotherapy regimen probably makes little to no difference in OS compared to other combinations, but likely improves PFS. Choice of chemotherapy will therefore be guided by symptoms from previous chemotherapy and other patient considerations. Single-agent PLD remains a useful agent for platinum-resistant relapsed EOC and choice of agent at relapse will depend on patient factors, e.g. degree of bone marrow suppression or neurotoxicity from previous treatments. Adding another agent to PLD likely increases overall grade ≥ 3 adverse events with little to no improvement in survival outcomes. The limited evidence relating to PLD in combination with other agents in platinum-resistant relapsed EOC does not indicate a benefit, but there is some evidence of increased side effects.

Immune checkpoint inhibitors in ovarian cancer: where do we go from here?

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and despite advancements in therapeutics, most women unfortunately still succumb to their disease. Immunotherapies, in particular immune checkpoint inhibitors (ICI), have been therapeutically transformative in many tumour types, including gynaecological malignancies such as cervical and endometrial cancer. Unfortunately, these therapeutic successes have not been mirrored in ovarian cancer clinical studies. This review provides an overview of the ovarian tumour microenvironment (TME), particularly factors associated with survival, and explores current research into immunotherapeutic strategies in EOC, with an exploratory focus on novel therapeutics in navigating drug resistance.

Preclinical Efficacy of the Antibody-Drug Conjugate CLDN6-23-ADC for the Treatment of CLDN6-Positive Solid Tumors

PURPOSE

Claudin-6 (CLDN6) is expressed at elevated levels in multiple human cancers including ovarian and endometrial malignancies, with little or no detectable expression in normal adult tissue. This expression profile makes CLDN6 an ideal target for development of a potential therapeutic antibody-drug conjugate (ADC). This study describes the generation and preclinical characterization of CLDN6-23-ADC, an ADC consisting of a humanized anti-CLDN6 monoclonal antibody coupled to monomethyl auristatin E (MMAE) via a cleavable linker.

EXPERIMENTAL DESIGN

A fully humanized anti-CLDN6 antibody was conjugated to MMAE resulting in the potential therapeutic ADC, CLDN6-23-ADC. The antitumor efficacy of CLDN6-23-ADC was assessed for antitumor efficacy in CLDN6-positive (CLDN6+) and -negative (CLDN6-) xenografts and patient-derived xenograft (PDX) models of human cancers.

RESULTS

CLDN6-23-ADC selectively binds to CLDN6, versus other CLDN family members, inhibits the proliferation of CLDN6+ cancer cells in vitro, and is rapidly internalized in CLDN6+ cells. Robust tumor regressions were observed in multiple CLDN6+ xenograft models and tumor inhibition led to markedly enhanced survival of CLDN6+ PDX tumors following treatment with CLDN6-23-ADC. IHC assessment of cancer tissue microarrays demonstrate elevated levels of CLDN6 in 29% of ovarian epithelial carcinomas. Approximately 45% of high-grade serous ovarian carcinomas and 11% of endometrial carcinomas are positive for the target.

CONCLUSIONS

We report the development of a novel ADC, CLDN6-23-ADC, that selectively targets CLDN6, a potential onco-fetal-antigen which is highly expressed in ovarian and endometrial cancers. CLDN6-23-ADC exhibits robust tumor regressions in mouse models of human ovarian and endometrial cancers and is currently undergoing phase I study.

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.

Targeting NaPi2b in ovarian cancer

Novel biomarkers are needed to direct new treatments for ovarian cancer, a disease for which the standard of care remains heavily focused on platinum-based chemotherapy. Despite the success of PARP inhibitors, treatment options are limited, particularly in the platinum-resistant setting. NaPi2b is a cell surface sodium-dependent phosphate transporter that regulates phosphate homeostasis under normal physiological conditions and is a lineage marker that is expressed in select cancers, including ovarian, lung, thyroid, and breast cancers, with limited expression in normal tissues. Based on its increased expression in ovarian tumors, NaPi2b is a promising candidate to be studied as a biomarker for treatment and patient selection in ovarian cancer. In preclinical studies, the use of antibodies against NaPi2b showed that this protein can be exploited for tumor mapping and therapeutic targeting. Emerging data from phase 1 and 2 clinical trials in ovarian cancer have suggested that NaPi2b can be successfully detected in patient biopsy samples using immunohistochemistry, and the NaPi2b-targeting antibody-drug conjugate under evaluation appeared to elicit therapeutic responses. The aim of this review is to examine literature supporting NaPi2b as a novel biomarker for potential treatment and patient selection in ovarian cancer and to discuss the critical next steps and future analyses necessary to drive the study of this biomarker and therapeutic targeting forward.

Exploration of the antibody-drug conjugate clinical landscape

The antibody-drug conjugate (ADC) field has undergone a renaissance, with substantial recent developmental investment and subsequent drug approvals over the past 6 y. In November 2022, ElahereTM became the latest ADC to be approved by the US Food and Drug Administration (FDA). To date, over 260 ADCs have been tested in the clinic against various oncology indications. Here, we review the clinical landscape of ADCs that are currently FDA approved (11), agents currently in clinical trials but not yet approved (164), and candidates discontinued following clinical testing (92). These clinically tested ADCs are further analyzed by their targeting tumor antigen(s), linker, payload choices, and highest clinical stage achieved, highlighting limitations associated with the discontinued drug candidates. Lastly, we discuss biologic engineering modifications preclinically demonstrated to improve the therapeutic index that if incorporated may increase the proportion of molecules that successfully transition to regulatory approval.

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.

Lipolysis-stimulated lipoprotein receptor-targeted antibody-drug conjugate demonstrates potent antitumor activity against epithelial ovarian cancer

BACKGROUND

Epithelial ovarian cancer (EOC) is a lethal malignant tumor, for which new treatment options are urgently required. Lipolysis-stimulated lipoprotein receptor (LSR) is widely expressed in EOC, and it is associated with poor prognosis. In this study, we developed an antibody-drug conjugate (ADC) targeting LSR as a new therapeutic approach to EOC.

METHODS

We, herein, developed novel anti-LSR monoclonal antibodies (mAbs) and an LSR-ADC by conjugating monomethyl auristatin E as a payload. We subsequently evaluated the in vitro and in vivo (on xenograft models) antitumor effect of the LSR-ADC.

RESULTS

An overexpression of LSR was observed not only in the primary EOC tumor but also in its lymph node and omental metastases. The EOC cell lines NOVC7-C and OVCAR3 strongly expressed LSR (as compared to ES2 cells). Both the anti-LSR mAb and the LSR-ADC were able to specifically bind to LSR-positive cells and were rapidly internalized and trafficked to the lysosomes. The LSR-ADC demonstrated a potent antitumor effect against NOVC-7C and OVCAR3, but little activity against ES2 cells. In vitro, the LSR-ADC exhibited a potent antitumor effect against NOVC-7C and OVCAR3. Moreover, in the OVCAR3 xenograft models as well as in the patient-derived xenograft models of LSR-positive EOC, the LSR-ADC significantly inhibited tumor growth. The LSR-ADC also suppressed the omental/bowel metastases in OVCAR3-Luc xenografts and improved the median survival.

CONCLUSION

The developed LSR-ADC demonstrated a significant antitumor activity against LSR-positive EOC cell lines and tumors. Our preclinical data support the use of the LSR-ADC as a novel therapy for patients with LSR-positive ovarian cancer.

Is antibody-drug conjugate a rising star for clinical treatment of solid tumors? A systematic review and meta-analysis

Antibody-drug conjugates (ADCs) show significant advantages in cancer treatment due to their high selectivity and anti-tumor activity, but the efficacy and safety of the treatment of solid tumors are unknown. We searched research databases, major conference proceedings and trial registries for randomized controlled trials (RCTs). Then, we selected qualified studies and extracted dates. Studies were assessed for quality, and a meta-analysis was conducted to quantify effects of ADCs on overall survival (OS), progression-free survival (PFS), overall response rate (ORR) and adverse events (AEs). The within-study heterogeneity was evaluated by subgroup and sensitivity analysis. Eleven RCTs with 4353 participants were included. ADCs had better PFS (HR: 0.69, 95 % CI: 0.56-0.82) and OS (HR: 0.76, 95 % CI: 0.61-0.92). ADCs resulted in lower risk of febrile neutropenia in blood system. Conversely, ADC therapy had not a prepotent on ORR (RR: 1.36, 95 % CI: 0.71-2.60).

Advancing antibody-drug conjugates in gynecological malignancies: myth or reality?

Antibody-drug conjugates (ADCs) represent a new class of therapeutic agents designed to target specific antigens on tumor cells, combining the specificity of monoclonal antibodies to the cytotoxicity of classic chemotherapy agents. These drugs have been extensively studied both in solid and hematologic malignancies, leading to substantial improvement in the therapeutic landscape for several tumors. Despite no ADC have been yet approved for the treatment of gynecological malignancies, some agents have shown promising results and might have the potential to become part of the standard of care. Among them, mirvetuximab soravtansine has shown activity in platinum-resistant ovarian cancer with high folate-α receptor expression, as a single agent and in combination. Tisotumab vedotin is active in patients with pre-treated cervical cancer, and further investigation is ongoing. The purpose of this review is to summarize the structural and functional characteristics of ADCs and analyze the most recent and promising data regarding the clinical development of ADCs in gynecological malignancies. The available data on the efficacy of the more studied ADCs in ovarian, endometrial, and cervical cancers will be discussed along with toxicities of special interest, the mechanisms of resistance, and future possible drugs combination.

Antibody-Drug Conjugate Targets, Drugs and Linkers

Antibody-drug conjugates offer the possibility of directing powerful cytotoxic agents to a malignant tumor while sparing normal tissue. The challenge is to select an antibody target expressed exclusively or at highly elevated levels on the surface of tumor cells and either not all or at low levels on normal cells. The current review explores 78 targets that have been explored as antibody-drug conjugate targets. Some of these targets have been abandoned, 9 or more are the targets of FDA-approved drugs, and most remain active clinical interest. Antibody-drug conjugates require potent cytotoxic drug payloads, several of these small molecules are discussed, as are the linkers between the protein component and small molecule components of the conjugates. Finally, conclusions regarding the elements for the successful antibody-drug conjugate are discussed.

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.

Stepping forward in antibody-drug conjugate development

Antibody-drug conjugates (ADCs) are cancer therapeutic agents comprised of an antibody, a linker and a small-molecule payload. ADCs use the specificity of the antibody to target the toxic payload to tumor cells. After intravenous administration, ADCs enter circulation, distribute to tumor tissues and bind to the tumor surface antigen. The antigen then undergoes endocytosis to internalize the ADC into tumor cells, where it is transported to lysosomes to release the payload. The released toxic payloads can induce apoptosis through DNA damage or microtubule inhibition and can kill surrounding cancer cells through the bystander effect. The first ADC drug was approved by the United States Food and Drug Administration (FDA) in 2000, but the following decade saw no new approved ADC drugs. From 2011 to 2018, four ADC drugs were approved, while in 2019 and 2020 five more ADCs entered the market. This demonstrates an increasing trend for the clinical development of ADCs. This review summarizes the recent clinical research, with a specific focus on how the in vivo processing of ADCs influences their design. We aim to provide comprehensive information about current ADCs to facilitate future development.

Simulating the Selection of Resistant Cells with Bystander Killing and Antibody Coadministration in Heterogeneous Human Epidermal Growth Factor Receptor 2-Positive Tumors

Intratumoral heterogeneity is a leading cause of treatment failure resulting in tumor recurrence. For the antibody-drug conjugate (ADC) ado-trastuzumab emtansine (T-DM1), two major types of resistance include changes in human epidermal growth factor receptor 2 (HER2) expression and reduced payload sensitivity, which is often exacerbated by heterogenous HER2 expression and ADC distribution during treatment. ADCs with bystander payloads, such as trastuzumab-monomethyl auristatin E (T-MMAE), can reach and kill adjacent cells with lower receptor expression that cannot be targeted directly with the ADC. Additionally, coadministration of T-DM1 with its unconjugated antibody, trastuzumab, can improve distribution and minimize heterogeneous delivery. However, the effectiveness of trastuzumab coadministration and ADC bystander killing in heterogenous tumors in reducing the selection of resistant cells is not well understood. Here, we use an agent-based model to predict outcomes with these different regimens. The simulations demonstrate that both T-DM1 and T-MMAE benefit from trastuzumab coadministration for tumors with high average receptor expression (up to 70% and 40% decrease in average tumor volume, respectively), with greater benefit for nonbystander payloads. However, the benefit decreases as receptor expression is reduced, reversing at low concentrations (up to 360% and 430% increase in average tumor volume for T-DM1 and T-MMAE, respectively) for this mechanism that impacts both ADC distribution and efficacy. For tumors with intrinsic payload resistance, coadministration uniformly exhibits better efficacy than ADC monotherapy (50%-70% and 19%-36% decrease in average tumor volume for T-DM1 and T-MMAE, respectively). Finally, we demonstrate that several regimens select for resistant cells at clinical tolerable doses, which highlights the need to pursue other mechanisms of action for durable treatment responses. SIGNIFICANCE STATEMENT: Experimental evidence demonstrates heterogeneity in the distribution of both the antibody-drug conjugate and the target receptor in the tumor microenvironment, which can promote the selection of resistant cells and lead to recurrence. This study quantifies the impact of increasing the antibody dose and utilizing bystander payloads in heterogeneous tumors. Alternative cell-killing mechanisms are needed to avoid enriching resistant cell populations.

Physicochemical and biological impact of metal-catalyzed oxidation of IgG1 monoclonal antibodies and antibody-drug conjugates via reactive oxygen species

Biotherapeutics are exposed to common transition metal ions such as Cu(II) and Fe(II) during manufacturing processes and storage. IgG1 biotherapeutics are vulnerable to reactive oxygen species (ROS) generated via the metal-catalyzed oxidation reactions. Exposure to these metal ions can lead to potential changes to structure and function, ultimately influencing efficacy, potency, and potential immunogenicity of the molecules. Here, we stress four biotherapeutics of the IgG1 subclass (trastuzumab, trastuzumab emtansine, anti-NaPi2b, and anti-NaPi2b-vc-MMAE) with two common pharmaceutically relevant metal-induced oxidizing systems, Cu(II)/ ascorbic acid and Fe(II)/ H₂O₂, and evaluated oxidation, size distribution, carbonylation, Fc effector functions, antibody-dependent cellular cytotoxicity (ADCC) activity, cell anti-proliferation and autophaghic flux. Our study demonstrates that the extent of oxidation was metal ion-dependent and site-specific, leading to decreased FcγRIIIa and FcRn receptor binding and subsequently potentially reduced bioactivity, though antigen binding was not affected to a great extent. In general, the monoclonal antibody (mAb) and corresponding antibody-drug conjugate (ADC) showed similar impacts to product quality when exposed to the same metal ion, either Cu(II) or Fe(II). Our study clearly demonstrates that transition metal ion binding to therapeutic IgG1 mAbs and ADCs is not random and that oxidation products show unique structural and functional ramifications. A critical outcome from this study is our highlighting of key process parameters, route of degradation, especially oxidation (metal catalyzed or via ROS), on the CH1 and Fc region of full-length mAbs and ADCs.

Abbreviations: DNPH 2,4-dinitrophenylhydrazine; ADC Antibody drug conjugate; ADCC Antibody-dependent cellular cytotoxicity; CDR Complementary determining region; DTT Dithiothreitol; HMWF high molecular weight form; LC-MS Liquid chromatography–mass spectrometry; LMWF low molecular weight forms; MOA Mechanism of action; MCO Metal-catalyzed oxidation; MetO Methionine sulfoxide; mAbs Monoclonal antibodies; MyBPC Myosin binding protein C; ROS Reactive oxygen species; SEC Size exclusion chromatography

Revisiting antibody-drug conjugates and their predictive biomarkers in platinum-resistant ovarian cancer

Until to date, platinum derived drugs are still the backbone of treating ovarian cancer (OC). Most patients treated with platinum-based chemotherapy develop resistance during the course of their management. The treatment of platinum-resistant ovarian cancer (PROC) is challenging. Few therapeutic options are available for patients with this aggressive disease. Besides, there are liminal advances regarding new anticancer drugs as well as validated predictive biomarkers of clinical outcomes in this setting. The enrollment of PROC patients in interventional studies is limited as compared to newly launched clinical trials for platinum-sensitive OC. Enthusiastically, the emergence of antibody-drug conjugates (ADCs) has provided promising findings for further clinical development in PROC. ADCs have the advantage to selectively deliver cytotoxic drugs to cancer cells expressing several of antigens using specific monoclonal antibodies based on the concept of immune bioconjugation. This innovative class of therapeutics showed encouraging early signs of clinical efficacy in PROC particularly mirvetuximab soravtansine that has been successfully introduced into three randomized and controlled phase III studies. In this review, the evidence from clinical trials supporting the development of ADCs targeting folate receptor alpha, sodium-dependent phosphate transporter 2B, dipeptidase 3, mesothelin, mucin 16, and tissue factor using various cytotoxic payloads in PROC is reviewed.

Emerging targeted drug delivery strategies toward ovarian cancer

Ovarian cancer is a high-mortality malignancy in women. The contemporary clinical chemotherapy with classic cytotoxic drugs, targeted molecular inhibitors would mostly fail when ovarian cancer cells become drug-resistant or metastasize through the body or when patients bare no more toleration because of strong adverse effects. The past decade has spotted varying targeted delivery systems including antibody-drug conjugates (ADCs), peptide/folate/aptamer-drug conjugates, polymer-drug conjugates, ligand-functionalized nanomedicines, and dual-targeted nanomedicines that upgrade ovarian cancer chemo- and molecular therapy effectively in preclinical/clinical settings via endowing therapeutic agents selectivity and bypassing drug resistance as well as lessening systemic toxicity. The targeted delivery approaches further provide means to potentiate emergent treatment modalities such as molecular therapy, gene therapy, protein therapy, photodynamic therapy, dual-targeting therapy and combination therapy for ovarian cancer. This review highlights up-to-date development of targeted drug delivery strategies toward advanced, metastatic, relapsed, and drug resistant ovarian cancers.

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.

An open-label phase I dose-escalation study of the safety and pharmacokinetics of DMUC4064A in patients with platinum-resistant ovarian cancer

OBJECTIVES

MUC16 is overexpressed in the majority of human epithelial ovarian cancers (OC). DMUC4064A is a humanized anti-MUC16 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin E. This trial assessed the safety, tolerability, pharmacokinetics, and preliminary activity of DMUC4064A in patients with platinum-resistant OC.

METHODS

DMUC4064A was administered once every 3 weeks to patients in 1.0-5.6 mg/kg dose escalation cohorts, followed by cohort expansion at the recommended Phase II dose (RP2D).

RESULTS

Sixty-five patients were enrolled and received a median of 5 cycles (range 1-20) of DMUC4064A. The maximum tolerated dose was not reached; 5.2 mg/kg was the RP2D based on the overall tolerability profile. The most common adverse events were fatigue, nausea, abdominal pain, constipation, blurred vision, diarrhea, and anemia. Sixteen patients (25%) experienced related grade ≥ 3 toxicities. Twenty-six patients (40%) experienced ocular toxicities. The exposure of acMMAE was dose proportional, with a half-life of ~6 days. Sixteen patients (25%) experienced confirmed objective partial response (PR or CR) starting at ≥3.2 mg/kg dose levels, while 23 (35%) patients had best responses of PR or CR. Overall, the clinical benefit rate was 42% (27 patients with a best response [confirmed and unconfirmed] of CR, or PR or SD lasting ≥6 months). Among the 54 patients with high MUC16 immunohistochemistry scores, the clinical benefit rate was 46% (25 patients). Median progression-free survival was 3.9 months overall.

CONCLUSIONS

In this Phase I study, DMUC4064A demonstrated a tolerable safety profile along with encouraging efficacy in the indication of platinum-resistant OC.

Chemotherapy resistance in epithelial ovarian cancer: Mechanisms and emerging treatments

Ovarian cancer (OC) remains a fatal malignancy because most patients experience recurrent disease, which is resistant to chemotherapy. The outcomes for patients with platinum-resistant OC are poor, response rates to further chemotherapy are low and median survival is lower than 12 months. The complexity of platinum-resistant OC, which comprises a heterogeneous spectrum of diseases, is indeed far from being completely understood. Therefore, comprehending tumors' biological behaviour to identify reliable biomarkers, which may predict responses to therapies, is a demanding challenge to improve OC management. In the age of precision medicine, efforts to overcome platinum resistance in OC represent a dynamic and vast field in which innovative drugs and clinical trials rapidly develop. This review will present the exceptional biochemical environment implicated in OC and highlights mechanisms of chemoresistance. Furthermore, innovative molecules and new therapeutic opportunities are presented, along with currently available therapies and ongoing clinical trials.

Progress in Gynecologic Cancers with Antibody Drug Conjugates

PURPOSE OF REVIEW

This article provides a comprehensive review of antibody-drug conjugates (ADCs) under investigation in gynecologic cancers. The structure and function of ADCs are reviewed with a focus on clinical benefit as well as toxicity profiles.

RECENT FINDINGS

Several ADCs with various target antigens have been investigated in ovarian, cervical, and endometrial cancer. ADCs have consistently demonstrated favorable safety/tolerability profiles both as monotherapy and in combination therapy. In ovarian cancer, response rates have ranged from 9 to 46% for monotherapy with response rates as high as 83% in combination therapy. In patients with cervical cancer with progressive disease despite doublet therapy and bevacizumab, response rates as high as 24% have been observed. ADCs represent a rapidly evolving field of targeted therapy which have demonstrated notable clinical benefit both as monotherapy but also in combination therapy with an overall favorable toxicity profile. With continued refinement of the target biomarkers utilized, improved clinical benefit is likely to be observed.

The Dolaflexin-based Antibody-Drug Conjugate XMT-1536 Targets the Solid Tumor Lineage Antigen SLC34A2/NaPi2b

Target selection for antibody-drug conjugates (ADC) frequently focuses on identifying antigens with differential expression in tumor and normal tissue, to mitigate the risk of on-target toxicity. However, this strategy restricts the possible target space. SLC34A2/NaPi2b is a sodium phosphate transporter expressed in a variety of human tumors including lung and ovarian carcinoma, as well as the normal tissues from which these tumors arise. Previous clinical trials with a NaPi2b targeting MMAE-ADCs have shown objective durable responses. However, the protein-based biomarker assay developed for use in that study was unable to discern a statistically significant relationship between NaPi2b protein expression and the probability of response. XMT-1536 is a NaPi2b targeting ADC comprised of a unique humanized antibody conjugated with 10-15 auristatin F- hydroxypropylamide (AF-HPA) payload molecules via the Dolaflexin platform. AF-HPA is a cell-permeable, antimitotic compound that is slowly metabolized intratumorally to an active, very low-permeable metabolite, auristatin F (AF), resulting in controlled bystander killing. We describe the preclinical in vitro and in vivo antitumor effects of XMT-1536 in models of ovarian and lung adenocarcinoma. Pharmacokinetic analysis showed approximately proportional increases in exposure in rat and monkey. Systemic free AF-HPA and AF concentrations were observed to be low in all animal species. Finally, we describe a unique IHC reagent, generated from a chimeric construct of the therapeutic antibody, that was used to derive a target expression and efficacy relationship in a series of ovarian primary xenograft cancer models.

The impact of Pegylated liposomal doxorubicin in recurrent ovarian cancer: an updated meta-analysis of randomized clinical trials

Background

Previous meta-analysis studies suggested that pegylated liposomal doxorubicin (PLD) may improve the survival rate of patients with recurrent ovarian cancer. The aim of the present meta-analysis, then, was to further update the role of PLD in the treatment of recurrent ovarian cancer.

Methods

We performed a literature search using the electronic databases Medicine, EMBASE, Web of Science, and the Cochrane Library to 27 July 2020. We only restricted the randomized clinical trials. Study-specific hazard ratios and 95% confidence interval (HR/95% CI) and risk ratios and 95% confidence interval (RR/95% CI) were pooled using a random-effects model.

Results

Ten studies (12 trials) were included after screening 940 articles. We categorized the eligible studies into two groups: the doublet regimens (four trials, 1767 patients) showed that PLD plus carbo provided superior progression-free survival (PFS) (HR, 0.85; 95% CI, 0.74–0.97) and similar overall survival (OS) (HR, 1.00; 95% CI, 0.88–1.14) compared to paclitaxel (PAC) plus carboplatin (carbo). PLD plus carbo was associated with significantly more anemia and thrombocytopenia, and other side effects were well tolerated. The monotherapy regimens (eight trials, 1980 patients) showed that PLD possessed a similar PFS (HR, 1.02; 95% CI, 0.90–1.16) and OS (HR, 0.88; 95% CI, 0.77–1.01) relative to other monotherapies. PLD alone was also more associated with mucositis/stomatitis and hand-foot syndrome, while other side effects were well tolerated.

Conclusions

In platinum-sensitive recurrent ovarian cancer, PLD plus carbo was more effective than PAC plus carbo, while in platinum-resistant or -refractory recurrent ovarian cancer, PLD exhibited similar survival to other monotherapies. Regarding side effects, PLD plus carbo and mono chemotherapy were both well tolerated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00790-4.

Therapeutic Nanobodies Targeting Cell Plasma Membrane Transport Proteins: A High-Risk/High-Gain Endeavor

Cell plasma membrane proteins are considered as gatekeepers of the cell and play a major role in regulating various processes. Transport proteins constitute a subclass of cell plasma membrane proteins enabling the exchange of molecules and ions between the extracellular environment and the cytosol. A plethora of human pathologies are associated with the altered expression or dysfunction of cell plasma membrane transport proteins, making them interesting therapeutic drug targets. However, the search for therapeutics is challenging, since many drug candidates targeting cell plasma membrane proteins fail in (pre)clinical testing due to inadequate selectivity, specificity, potency or stability. These latter characteristics are met by nanobodies, which potentially renders them eligible therapeutics targeting cell plasma membrane proteins. Therefore, a therapeutic nanobody-based strategy seems a valid approach to target and modulate the activity of cell plasma membrane transport proteins. This review paper focuses on methodologies to generate cell plasma membrane transport protein-targeting nanobodies, and the advantages and pitfalls while generating these small antibody-derivatives, and discusses several therapeutic nanobodies directed towards transmembrane proteins, including channels and pores, adenosine triphosphate-powered pumps and porters.

A Phase I Study of DLYE5953A, an Anti-LY6E Antibody Covalently Linked to Monomethyl Auristatin E, in Patients with Refractory Solid Tumors

PURPOSE

DLYE5953A is an antibody-drug conjugate consisting of an anti-LY6E antibody covalently linked to the cytotoxic agent monomethyl auristatin E. This study characterized the safety, pharmacokinetics, immunogenicity, potential biomarkers, and antitumor activity of DLYE5953A in patients with metastatic solid tumors.

PATIENTS AND METHODS

This was a phase I, open-label, 3+3 dose-escalation, and dose-expansion study of DLYE5953A administered intravenously every 21 days (Q3W) in patients with locally advanced or metastatic solid malignancies.

RESULTS

Sixty-eight patients received DLYE5953A (median, four cycles; range, 1-27). No dose-limiting toxicities were identified during dose escalation (0.2-2.4 mg/kg; n = 20). The recommended phase II dose (RP2D) of 2.4 mg/kg Q3W was based on overall safety and tolerability. Dose-expansion cohorts for HER2-negative metastatic breast cancer (HER2-negative MBC; n = 23) and non-small cell lung cancer (NSCLC; n = 25) patients were enrolled at the RP2D. Among patients receiving DLYE5953A 2.4 mg/kg (n = 55), the most common (≥30%) related adverse events (AEs) included alopecia, fatigue, nausea, and peripheral neuropathy. Grade ≥3 related AEs occurred in 14 of 55 (26%) patients, with neutropenia being the most common (13%). DLYE5953A demonstrated linear total antibody pharmacokinetics at doses of ≥0.8 mg/kg with low unconjugated monomethyl auristatin E levels in blood. Partial response was confirmed in eight of 68 (12%) patients, including three of 29 patients with MBC (10%) and five of 25 patients with NSCLC (20%) at the RP2D. Stable disease was the best response for 37 of 68 (54%) patients.

CONCLUSIONS

DLYE5953A administered at 2.4 mg/kg has acceptable safety. Preliminary evidence of antitumor activity in patients with HER2-negative MBC and NSCLC supports further investigation of LY6E as a therapeutic target.

Enfortumab Vedotin-ejfv: A First-in-Class Anti-Nectin-4 Antibody-Drug Conjugate for the Management of Urothelial Carcinoma

OBJECTIVE

To evaluate the pharmacology, pharmacokinetics, clinical efficacy, safety, dosing, cost, and clinical implications of enfortumab vedotin-ejfv (EV) in the treatment of locally advanced or metastatic urothelial carcinoma (UC).

DATA SOURCES

A literature search of PubMed (inception to August 2020) was conducted using the terms enfortumab, vedotin, Padcev, and Nectin. Data were also obtained from package inserts, meeting abstracts, and ongoing studies from ClinicalTrials.gov.

STUDY SELECTION AND DATA EXTRACTION

All relevant published articles, package inserts, and meeting abstracts evaluating EV for the treatment of UC were analyzed.

DATA SYNTHESIS

Antibody-drug conjugates (ADCs) deliver potent cytotoxic agents using highly selective monoclonal antibodies. Targeting the near-universal expression of Nectin-4 on UC cells is a viable therapeutic strategy. In a pivotal phase II trial, EV demonstrated an overall response rate of 44%, and a median duration of response of 7.6 months. Estimated overall survival was 11.7 months with a median estimated progression-free survival of 5.6 months. Results were similar among difficult-to-treat patients, including those with liver metastases. Unique toxicity concerns with EV require careful consideration and monitoring.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

EV, a first-in-class anti-Nectin-4 ADC, provides impressive response rates with manageable toxicities, making it a promising treatment option for patients with multiply relapsed or refractory UC.

CONCLUSION

The US Food and Drug Administration-approved EV demonstrates antitumor activity in heavily pretreated patients with UC but harbors important adverse effects and financial concerns. Additional studies are required to identify the optimal sequencing, patient population, and place in therapy for EV.

Antibody-Drug Conjugates: A Promising Novel Therapy for the Treatment of Ovarian Cancer

Antibody-drug conjugates (ADCs) represent a novel and promising therapeutic strategy for the treatment of cancer patients. ADCs target antigens highly expressed on the membrane surface of tumor cells to selectively deliver a cytotoxic drug. Ovarian tumors differentially express tumor-specific antigens, which can be used to guide ADCs. This strategy allows for optimizing tumor targeting while minimizing systemic toxicity compared to classical chemotherapeutic agents. ADCs can be improved by using a cleavable linker allowing the delivery of the toxic payload in surrounding cells not expressing the target protein, therefore acting on heterogeneous tumors with different cell populations. Currently, more than 15 ADCs are under preclinical investigation in ovarian cancer, and some of them have already been tested in early-phase clinical trials with promising results. In this review, we summarize the mechanism of action and the toxicity profile of ADCs and discuss the latest preclinical discoveries and forthcoming applications in ovarian cancer.

Improved targeting of an anti-TAG-72 antibody drug conjugate for the treatment of ovarian cancer

INTRODUCTION

Ovarian cancer has only a 17% 5-year survival rate in patients diagnosed with late stage disease. Tumor-associated glycoprotein-72 (TAG72), expressed in 88% of all stages of ovarian cancer, is an excellent candidate for antibody-targeted therapy, as it is not expressed in normal human adult tissues, except in the secretory endometrium.

METHODS

Using the clinically relevant anti-TAG72 murine monoclonal antibody CC49, we evaluated antibody drug conjugates (ADCs) incorporating the highly potent, synthetic antimitotic agent monomethylauristatin E (MMAE). MMAE was conjugated to CC49 via reduced disulfides in the hinge region, using three different types of linker chemistry, vinylsulfone (VS-MMAE), bromoacetamido (Br-MMAE), and maleimido (mal-MMAE).

RESULTS

The drug antibody ratios (DARs) of the three ADCs were 2.3 for VS-MMAE, 10 for Br-MMAE, and 9.5 for mal-MMAE. All three ADCs exhibited excellent tumor to blood ratios on PET imaging, but the absolute uptake of CC49-mal-MMAE (3.3%ID/g) was low compared to CC49-Br-MMAE (6.43%ID/g), at 142 hours. Blood clearance at 43 hours was 38% for intact CC49, about 24% for both CC49-VS-MMAE and CC49-Br-MMAE, and 7% for CC49-mal-MMAE. CC49-VS-MMAE was not further studied due to its low DAR, while CC49-mal-MMAE was ineffective in the OVCAR3 xenograft likely due to its rapid blood clearance. In contrast, CC49-Br-MMAE treated mice exhibited an average of a 15.6 day tumor growth delay and a 40% increase in survival vs controls with four doses of 7.5 or 15 mg/kg of CC49-Br-MMAE.

CONCLUSION

We conclude that CC49-Br-MMAE with a high DAR and stable linker performs well in a difficult to treat solid tumor model.

Patient Selection Strategies to Maximize Therapeutic Index of Antibody-Drug Conjugates: Prior Approaches and Future Directions

Antibody-drug conjugates (ADC) are targeted agents that have shown promise in treating cancer. A central challenge in development of ADCs is the relatively narrow therapeutic index observed in clinical studies. Patient selection strategies based on expression of the target in tumors have the potential to maximize benefit and provide the best chance of clinical success; however, implementation of biomarker-driven trials can be difficult both practically and scientifically. We conducted a survey of recent clinical experience from early-phase ADC trials completed between 2000 and 2019 to evaluate the different approaches to patient selection currently being used and assess whether there is evidence that target expression is associated with clinical activity. Our analysis of patient selection strategies indicates that optimal trial design for early-stage trials should be based on multiple factors, including prevalence and heterogeneity of target expression among intent-to-treat patients, as well as biological factors influencing expression of cell surface and soluble target. To ensure a high probability of success, early implementation of patient selection strategies centered around target expression are pivotal to development of ADCs. In this review, we propose a strategic approach that can be applied for optimization of trial design.

Phase 1b study of anti-NaPi2b antibody-drug conjugate lifastuzumab vedotin (DNIB0600A) in patients with platinum-sensitive recurrent ovarian cancer

OBJECTIVE

This study investigated the safety and tolerability of lifastuzumab vedotin (DNIB0600A) (LIFA), an antibody-drug conjugate, in patients with recurrent platinum-sensitive ovarian cancer (PSOC).

METHODS

In this open-label, multicenter phase 1b study, LIFA was administered intravenously once every 3 weeks (Q3W) with starting dose 1.2 mg/kg in a 3 + 3 dose-escalation scheme. All patients received carboplatin at dose AUC 6 mg/mL·min (AUC6) Q3W for up to 6 cycles. Dose expansion cohorts were enrolled ± bevacizumab 15 mg/kg Q3W.

RESULTS

Patients received LIFA at 1.2, 1.8, and 2.4 mg (n = 4, 5, and 20, respectively) with carboplatin. The maximum tolerated dose was not reached. The recommended phase 2 dose (RP2D) was LIFA 2.4 mg/kg + carboplatin AUC6 (cycles 1-6), with or without bevacizumab 15 mg/kg. Twelve patients received RP2D with bevacizumab. All patients experienced ≥1 adverse event (AE). The most common treatment-related AEs were neutropenia, peripheral neuropathy, thrombocytopenia, nausea, fatigue, anemia, diarrhea, vomiting, hypomagnesaemia, aspartate aminotransferase increased, alanine aminotransferase increased, and alopecia. Thirty-four (83%) patients experienced grade ≥ 3 AEs, the most frequent of which were neutropenia and thrombocytopenia. Nine (22%) patients experienced serious AEs. Pulmonary toxicities (34%), considered a potential risk of LIFA, included one patient who discontinued study treatment due to grade 2 pneumonitis. The median duration of progression-free survival was 10.71 months (95% CI: 8.54, 13.86) with confirmed complete/partial responses in 24 (59%) patients. Pharmacokinetics of mono-therapy LIFA was similar in combination therapy.

CONCLUSION

LIFA in combination with carboplatin ± bevacizumab demonstrated acceptable safety and encouraging activity in PSOC patients.

Antibody-drug conjugates for the treatment of ovarian cancer

INTRODUCTION

Ovarian cancer typically presents at an advanced stage and while initial chemotherapy response rates are favorable, a majority of patients experience recurrence with the subsequent development of chemoresistance. Recurrent, platinum-resistant disease is associated with a very poor prognosis as treatment in this setting is often limited by systemic toxicity. Antibody-drug conjugates (ADCs) are novel therapeutic agents designed to target antigens specific to ovarian tumor cells with direct delivery of cytotoxic agents to combat recurrent, platinum-resistant disease while limiting systemic toxicity.

AREAS COVERED

The basic structure and function of ADCs will be reviewed as well as the current data on ADCs under investigation in ovarian cancer.

EXPERT OPINION

ADCs represent a promising class of targeted therapy in recurrent ovarian cancer with excellent response rates particularly when utilized as combination therapy. While mirvetuximab soravtansine is the only ADC that has been evaluated in a phase 3 trial, many other ADCs and trials are on the horizon. As the field of targeted therapy continues to evolve, continued development of target antigens and ADCs are likely to represent a key development in treatment of recurrent, platinum-resistant disease.

A New Method to Model and Predict Progression Free Survival Based on Tumor Growth Dynamics

Progression-free survival (PFS) has been increasingly used as a primary endpoint for early clinical development. The aim of the present work was to develop a model where target lesion dynamics and risk for nontarget progression are jointly modeled for predicting PFS. The model was developed based on a pooled platinum-resistant ovarian cancer dataset comprising four different treatments and a wide range of dose levels. The target lesion progression was derived from tumor growth dynamics based on the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. The nontarget progression hazard was correlated to the first derivative of target lesion tumor size with respect to time. The PFS time was determined by the first occurring event, target lesion progression, or nontarget progression. The final joint model not only captured target lesion tumor growth dynamics but also predicted PFS well. A similar approach can potentially be used to predict PFS in future oncology studies.

Nanomedicine review: clinical developments in liposomal applications

Background

In recent years, disease treatment has evolved strategies that require increase in pharmaceutical agent’s efficacy and selectivity while decreasing their toxicity in normal tissues. These requirements have led to the development of nanoscale liposome systems for drug release. This review focuses on lipid features, pharmacological properties of liposomal formulations and the clinical studies of their application.

Main body

Several lipids are available, but their properties could affect pharmacological or clinical efficiency of drug formulations. Many liposomal formulations have been developed and are currently on the market. Proper selection of lipid is essential for the pharmacological effect to be improved. Most of the formulations use mainly zwitterionic, cationic or anionic lipids, PEG and/or cholesterol, which have different effects on stability, pharmacokinetics and delivery of the drug formulation. Clinical trials have shown that liposomes are pharmacologically and pharmacokinetically more efficient than drug-alone formulations in treating acute myeloid leukemia, hepatitis A, pain management, ovary, gastric breast and lung cancer, among others.

Conclusion

Liposomal formulations are less toxic than drugs alone and have better pharmacological parameters. Although they seem to be the first choice for drug delivery systems for various diseases, further research about dosage regimen regarding dose and time needs to be carried out.

Precision medicine for human cancers with Notch signaling dysregulation (Review)

NOTCH1, NOTCH2, NOTCH3 and NOTCH4 are transmembrane receptors that transduce juxtacrine signals of the delta-like canonical Notch ligand (DLL)1, DLL3, DLL4, jagged canonical Notch ligand (JAG)1 and JAG2. Canonical Notch signaling activates the transcription of BMI1 proto-oncogene polycomb ring finger, cyclin D1, CD44, cyclin dependent kinase inhibitor 1A, hes family bHLH transcription factor 1, hes related family bHLH transcription factor with YRPW motif 1, MYC, NOTCH3, RE1 silencing transcription factor and transcription factor 7 in a cellular context-dependent manner, while non-canonical Notch signaling activates NF-κB and Rac family small GTPase 1. Notch signaling is aberrantly activated in breast cancer, non-small-cell lung cancer and hematological malignancies, such as T-cell acute lymphoblastic leukemia and diffuse large B-cell lymphoma. However, Notch signaling is inactivated in small-cell lung cancer and squamous cell carcinomas. Loss-of-function NOTCH1 mutations are early events during esophageal tumorigenesis, whereas gain-of-function NOTCH1 mutations are late events during T-cell leukemogenesis and B-cell lymphomagenesis. Notch signaling cascades crosstalk with fibroblast growth factor and WNT signaling cascades in the tumor microenvironment to maintain cancer stem cells and remodel the tumor microenvironment. The Notch signaling network exerts oncogenic and tumor-suppressive effects in a cancer stage- or (sub)type-dependent manner. Small-molecule γ-secretase inhibitors (AL101, MRK-560, nirogacestat and others) and antibody-based biologics targeting Notch ligands or receptors [ABT-165, AMG 119, rovalpituzumab tesirine (Rova-T) and others] have been developed as investigational drugs. The DLL3-targeting antibody-drug conjugate (ADC) Rova-T, and DLL3-targeting chimeric antigen receptor-modified T cells (CAR-Ts), AMG 119, are promising anti-cancer therapeutics, as are other ADCs or CAR-Ts targeting tumor necrosis factor receptor superfamily member 17, CD19, CD22, CD30, CD79B, CD205, Claudin 18.2, fibroblast growth factor receptor (FGFR)2, FGFR3, receptor-type tyrosine-protein kinase FLT3, HER2, hepatocyte growth factor receptor, NECTIN4, inactive tyrosine-protein kinase 7, inactive tyrosine-protein kinase transmembrane receptor ROR1 and tumor-associated calcium signal transducer 2. ADCs and CAR-Ts could alter the therapeutic framework for refractory cancers, especially diffuse-type gastric cancer, ovarian cancer and pancreatic cancer with peritoneal dissemination. Phase III clinical trials of Rova-T for patients with small-cell lung cancer and a phase III clinical trial of nirogacestat for patients with desmoid tumors are ongoing. Integration of human intelligence, cognitive computing and explainable artificial intelligence is necessary to construct a Notch-related knowledge-base and optimize Notch-targeted therapy for patients with cancer.

Antibody-drug conjugates for ovarian cancer: current clinical development

PURPOSE OF REVIEW

Antibody drug conjugates (ADC) are a novel class of cancer therapeutics, delivering cytotoxic therapy directly to cancer cells, and show promise in the management of platinum-resistant ovarian cancer. Herein we summarize the ADC landscape currently in clinical study.

RECENT FINDINGS

Mirvetuximab Soravtansine, IMGN853, is an ADC targeting the folate receptor alpha (FRα) and has demonstrated promising single agent activity and a favorable toxicity profile in FRα-positive, platinum-resistant, epithelial ovarian cancer (EOC). The antitumor effect is seen primarily in less heavily pretreated EOC patients with moderate-to-high FRα tumor expression. A phase III study, randomizing patients to either IMGN853 or the physician's choice of single-agent chemotherapy has completed accrual. Additional ADC are being evaluated in ovarian cancer including agents that target NaPiB2, Trop2, mesothelin, and MUC16 are in phase 1 clinical trials.

SUMMARY

ADC bind antigens overexpressed on cancer cells and provide site-selective drug delivery, with the goal to increase therapeutic efficacy of cytotoxics while decreasing the off-target toxicity of the payloads. With appropriate antigen selection and adequate, measurable antigen threshold targets, these new agents may provide an improved strategy for overcoming resistance to standard chemotherapy in ovarian cancer.

Doxorubicin combined with betulinic acid or lonidamine in RGD ligand-targeted pH-sensitive micellar system for ovarian cancer treatment

Synergistic combination therapy involving the integration of chemotherapeutics and chemosensitizers into micelles has demonstrated great potential for tumor-specific location release. Here, the natural product betulinic acid (BA) and chemical drug lonidamine (LN) were used as chemosensitizers in combination with doxorubicin (DOX) for ovarian cancer treatment. We designed pH-sensitive peptide derivatives and constructed an all-in-one multifunctional multidrug pH-sensitive targeting delivery system for the synergistic co-delivery of DOX and BA (or LN). The combination of DOX and BA was found to elicit better therapeutic effects and lower cardiotoxicity than the DOX and LN combination in Skvo3 cells. Further, loading DOX/BA into the present micellar systems enabled burst release at the tumor location, leading to enhanced anti-tumor effects and reduced off-target effects. More importantly, DOX/BA micelles elicited fewer adverse effects on cardiac function and leukocyte counts in Skvo3 subcutaneous xenograft models. These features suggest that the designed micelles represent a promising multifunctional strategy for the efficient treatment of ovarian cancer.