A Biomarker-enriched, Randomized Phase II Trial of Adavosertib (AZD1775) Plus Paclitaxel and Carboplatin for Women with Platinum-sensitive TP53-mutant Ovarian Cancer

A Novel Non-Psychoactive Fatty Acid from a Marine Snail, Conus inscriptus, Signals Cannabinoid Receptor 1 (CB1) to Accumulate Apoptotic C16:0 and C18:0 Ceramides in Teratocarcinoma Cell Line PA1

The cannabinoid-type I (CB1) receptor functions as a double-edged sword to decide cell fate: apoptosis/survival. Elevated CB1 receptor expression is shown to cause acute ceramide accumulation to meet the energy requirements of fast-growing cancers. However, the flip side of continual CB1 activation is the initiation of a second ceramide peak that leads to cell death. In this study, we used ovarian cancer cells, PA1, which expressed CB1, which increased threefold when treated with a natural compound, bis(palmitoleic acid) ester of a glycerol (C2). This novel compound is isolated from a marine snail, Conus inscriptus, using hexane and the structural details are available in the public domain PubChem database (ID: 14275348). The compound induced two acute ceramide pools to cause G0/G1 arrest and killed cells by apoptosis. The compound increased intracellular ceramides (C:16 to 7 times and C:18 to 10 times), both of which are apoptotic inducers in response to CB1 signaling and thus the compound is a potent CB1 agonist. The compound is not genotoxic because it did not induce micronuclei formation in non-cancerous Chinese hamster ovarian (CHO) cells. Since the compound induced the cannabinoid pathway, we tested if there was a psychotropic effect in zebrafish models, however, it was evident that there were no observable neurobehavioral changes in the treatment groups. With the available data, we propose that this marine compound is safe to be used in non-cancerous cells as well as zebrafish. Thus, this anticancer compound is non-toxic and triggers the CB1 pathway without causing psychotropic effects.

Safety, tolerability, pharmacokinetics, and antitumor activity of adavosertib in Japanese patients with advanced solid tumors: A phase I, open-label study

INTRODUCTION

We aimed to assess the safety, pharmacokinetic profile, and antitumor activity of adavosertib monotherapy in Japanese patients with advanced solid tumors.

MATERIALS AND METHODS

This was a single-center, open-label, phase I study with two consecutive cohorts (250 mg and 200 mg cohorts). Patients received adavosertib at 250 mg or 200 mg, orally once daily for 5 days on and 2 days off for Weeks 1 and 2 of a 21-day cycle.

RESULTS

Dose-limiting toxicities (Grade 3 febrile neutropenia) occurred in 2/6 patients in the 250 mg cohort. None of the three patients in the 200 mg cohort developed dose-limiting toxicities. The most frequent treatment-emergent adverse event was nausea (250 mg: 83.3 %; 200 mg: 100.0 %). Median time to peak drug concentration was 4.03 and 2.08 h after the first dose and 2.82 and 1.90 h after multiple dosing in the 250 and 200 mg cohorts, respectively; respective mean terminal elimination half-lives were 7.36 and 7.30 h (first dose) and 10.55 and 8.88 h (multiple dosing). Systemic exposure increased in a slightly more than dose-proportional manner. No RECIST v1.1 response was observed. Disease control rate was 0 % and 33.3 % in the 250 and 200 mg cohorts, respectively. One patient (33.3 %) in the 200 mg cohort showed a best overall response of stable disease at ≥ 8 weeks; the rest showed progressive disease.

CONCLUSIONS

Adavosertib 200 mg once daily was well tolerated in this patient population and no safety concerns were raised. Exposure increased in a slightly more than dose-proportional manner and limited antitumor activity was shown.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04462952.

Translating p53-based therapies for cancer into the clinic

Inactivation of the most important tumour suppressor gene TP53 occurs in most, if not all, human cancers. Loss of functional wild-type p53 is achieved via two main mechanisms: mutation of the gene leading to an absence of tumour suppressor activity and, in some cases, gain-of-oncogenic function; or inhibition of the wild-type p53 protein mediated by overexpression of its negative regulators MDM2 and MDMX. Because of its high potency as a tumour suppressor and the dependence of at least some established tumours on its inactivation, p53 appears to be a highly attractive target for the development of new anticancer drugs. However, p53 is a transcription factor and therefore has long been considered undruggable. Nevertheless, several innovative strategies have been pursued for targeting dysfunctional p53 for cancer treatment. In mutant p53-expressing tumours, the predominant strategy is to restore tumour suppressor function with compounds acting either in a generic manner or otherwise selective for one or a few specific p53 mutations. In addition, approaches to deplete mutant p53 or to target vulnerabilities created by mutant p53 expression are currently under development. In wild-type p53 tumours, the major approach is to protect p53 from the actions of MDM2 and MDMX by targeting these negative regulators with inhibitors. Although the results of at least some clinical trials of MDM2 inhibitors and mutant p53-restoring compounds are promising, none of the agents has yet been approved by the FDA. Alternative strategies, based on a better understanding of p53 biology, the mechanisms of action of compounds and treatment regimens as well as the development of new technologies are gaining interest, such as proteolysis-targeting chimeras for MDM2 degradation. Other approaches are taking advantage of the progress made in immune-based therapies for cancer. In this Review, we present these ongoing clinical trials and emerging approaches to re-evaluate the current state of knowledge of p53-based therapies for cancer.

Cell fate regulation governed by p53: Friends or reversible foes in cancer therapy

Cancer is a leading cause of death worldwide. Targeted therapies aimed at key oncogenic driver mutations in combination with chemotherapy and radiotherapy as well as immunotherapy have benefited cancer patients considerably. Tumor protein p53 (TP53), a crucial tumor suppressor gene encoding p53, regulates numerous downstream genes and cellular phenotypes in response to various stressors. The affected genes are involved in diverse processes, including cell cycle arrest, DNA repair, cellular senescence, metabolic homeostasis, apoptosis, and autophagy. However, accumulating recent studies have continued to reveal novel and unexpected functions of p53 in governing the fate of tumors, for example, functions in ferroptosis, immunity, the tumor microenvironment and microbiome metabolism. Among the possibilities, the evolutionary plasticity of p53 is the most controversial, partially due to the dizzying array of biological functions that have been attributed to different regulatory mechanisms of p53 signaling. Nearly 40 years after its discovery, this key tumor suppressor remains somewhat enigmatic. The intricate and diverse functions of p53 in regulating cell fate during cancer treatment are only the tip of the iceberg with respect to its equally complicated structural biology, which has been painstakingly revealed. Additionally, TP53 mutation is one of the most significant genetic alterations in cancer, contributing to rapid cancer cell growth and tumor progression. Here, we summarized recent advances that implicate altered p53 in modulating the response to various cancer therapies, including chemotherapy, radiotherapy, and immunotherapy. Furthermore, we also discussed potential strategies for targeting p53 as a therapeutic option for cancer.

Key Proteins of Replication Stress Response and Cell Cycle Control as Cancer Therapy Targets

Replication stress (RS) is a characteristic state of cancer cells as they tend to exchange precision of replication for fast proliferation and increased genomic instability. To overcome the consequences of improper replication control, malignant cells frequently inactivate parts of their DNA damage response (DDR) pathways (the ATM-CHK2-p53 pathway), while relying on other pathways which help to maintain replication fork stability (ATR-CHK1). This creates a dependency on the remaining DDR pathways, vulnerability to further destabilization of replication and synthetic lethality of DDR inhibitors with common oncogenic alterations such as mutations of TP53, RB1, ATM, amplifications of MYC, CCNE1 and others. The response to RS is normally limited by coordination of cell cycle, transcription and replication. Inhibition of WEE1 and PKMYT1 kinases, which prevent unscheduled mitosis entry, leads to fragility of under-replicated sites. Recent evidence also shows that inhibition of Cyclin-dependent kinases (CDKs), such as CDK4/6, CDK2, CDK8/19 and CDK12/13 can contribute to RS through disruption of DNA repair and replication control. Here, we review the main causes of RS in cancers as well as main therapeutic targets-ATR, CHK1, PARP and their inhibitors.

An update of predictive biomarkers related to WEE1 inhibition in cancer therapy

PURPOSE

WEE1 is a crucial kinase involved in the regulation of G2/M checkpoint within the cell cycle. This article aims to comprehensively review the existing knowledge on the implication of WEE1 as a therapeutic target in tumor progression and drug resistance. Furthermore, we summarize the current predictive biomarkers employed to treat cancer with WEE1 inhibitors.

METHODS

A systematic review of the literature was conducted to analyze the association between WEE1 inhibition and cancer progression, including tumor advancement and drug resistance. Special attention was paid to the identification and utilization of predictive biomarkers related to therapeutic response to WEE1 inhibitors.

RESULTS

The review highlights the intricate involvement of WEE1 in tumor progression and drug resistance. It synthesizes the current knowledge on predictive biomarkers employed in WEE1 inhibitor treatments, offering insights into their prognostic significance. Notably, the article elucidates the potential for precision medicine by understanding these biomarkers in the context of tumor treatment outcomes.

CONCLUSION

WEE1 plays a pivotal role in tumor progression and is a promising therapeutic target. Distinguishing patients that would benefit from WEE1 inhibition will be a major direction of future research.

Drug-Resistant Epithelial Ovarian Cancer: Current and Future Perspectives

Epithelial ovarian cancer (EOC) is a complex disease with diverse histological subtypes, which, based on the aggressiveness and course of disease progression, have recently been broadly grouped into type I (low-grade serous, endometrioid, clear cell, and mucinous) and type II (high-grade serous, high-grade endometrioid, and undifferentiated carcinomas) categories. Despite substantial differences in pathogenesis, genetics, prognosis, and treatment response, clinical diagnosis and management of EOC remain similar across the subtypes. Debulking surgery combined with platinum-taxol-based chemotherapy serves as the initial treatment for High Grade Serous Ovarian Carcinoma (HGSOC), the most prevalent one, and for other subtypes, but most patients exhibit intrinsic or acquired resistance and recur in short duration. Targeted therapies, such as anti-angiogenics (e.g., bevacizumab) and PARP inhibitors (for BRCA-mutated cancers), offer some success, but therapy resistance, through various mechanisms, poses a significant challenge. This comprehensive chapter delves into emerging strategies to address these challenges, highlighting factors like aberrant miRNAs, metabolism, apoptosis evasion, cancer stem cells, and autophagy, which play pivotal roles in mediating resistance and disease relapse in EOC. Beyond standard treatments, the focus of this study extends to alternate targeted agents, including immunotherapies like checkpoint inhibitors, CAR T cells, and vaccines, as well as inhibitors targeting key oncogenic pathways in EOC. Additionally, this chapter covers disease classification, diagnosis, resistance pathways, standard treatments, and clinical data on various emerging approaches, and advocates for a nuanced and personalized approach tailored to individual subtypes and resistance mechanisms, aiming to enhance therapeutic outcomes across the spectrum of EOC subtypes.

Adavosertib and beyond: Biomarkers, drug combination and toxicity of WEE1 inhibitors

WEE1 kinase is renowned as an S-G2 checkpoint inhibitor activated by ATR-CHK1 in response to replication stress. WEE1 inhibition enhances replication stress and effectively circumvents checkpoints into mitosis, which triggers significant genetic impairs and culminates in cell death. This approach has been validated clinically for its promising anti-tumor efficacy across various cancer types, notably in cases of ovarian cancers. Nonetheless, the initial stage of clinical trials has shown that the first-in-human WEE1 inhibitor adavosertib is limited by dose-limiting adverse events. As a result, recent efforts have been made to explore predictive biomarkers and smart combination schedules to alleviate adverse effects. In this review, we focused on the exploration of therapeutic biomarkers, as well as schedules of combination utilizing WEE1 inhibitors and canonical anticancer drugs, according to the latest preclinical and clinical studies, indicating that the optimal application of WEE1 inhibitors will likely be as part of dose-reducing combination and be tailored to specific patient populations.

Adavosertib Enhances Antitumor Activity of Trastuzumab Deruxtecan in HER2-Expressing Cancers

PURPOSE

Cyclin E (CCNE1) has been proposed as a biomarker of sensitivity to adavosertib, a Wee1 kinase inhibitor, and a mechanism of resistance to HER2-targeted therapy.

EXPERIMENTAL DESIGN

Copy number and genomic sequencing data from The Cancer Genome Atlas and MD Anderson Cancer Center databases were analyzed to assess ERBB2 and CCNE1 expression. Molecular characteristics of tumors and patient-derived xenografts (PDX) were assessed by next-generation sequencing, whole-exome sequencing, fluorescent in situ hybridization, and IHC. In vitro, CCNE1 was overexpressed or knocked down in HER2+ cell lines to evaluate drug combination efficacy. In vivo, NSG mice bearing PDXs were subjected to combinatorial therapy with various treatment regimens, followed by tumor growth assessment. Pharmacodynamic markers in PDXs were characterized by IHC and reverse-phase protein array.

RESULTS

Among several ERBB2-amplified cancers, CCNE1 co-amplification was identified (gastric 37%, endometroid 43%, and ovarian serous adenocarcinoma 41%). We hypothesized that adavosertib may enhance activity of HER2 antibody-drug conjugate trastuzumab deruxtecan (T-DXd). In vitro, sensitivity to T-DXd was decreased by cyclin E overexpression and increased by knockdown, and adavosertib was synergistic with topoisomerase I inhibitor DXd. In vivo, the T-DXd + adavosertib combination significantly increased γH2AX and antitumor activity in HER2 low, cyclin E amplified gastroesophageal cancer PDX models and prolonged event-free survival (EFS) in a HER2-overexpressing gastroesophageal cancer model. T-DXd + adavosertib treatment also increased EFS in other HER2-expressing tumor types, including a T-DXd-treated colon cancer model.

CONCLUSIONS

We provide rationale for combining T-DXd with adavosertib in HER2-expressing cancers, especially with co-occuring CCNE1 amplifications. See related commentary by Rolfo et al., p. 4317.

Unveiling the novel immune and molecular signatures of ovarian cancer: insights and innovations from single-cell sequencing

Ovarian cancer is a highly heterogeneous and lethal malignancy with limited treatment options. Over the past decade, single-cell sequencing has emerged as an advanced biological technology capable of decoding the landscape of ovarian cancer at the single-cell resolution. It operates at the level of genes, transcriptomes, proteins, epigenomes, and metabolisms, providing detailed information that is distinct from bulk sequencing methods, which only offer average data for specific lesions. Single-cell sequencing technology provides detailed insights into the immune and molecular mechanisms underlying tumor occurrence, development, drug resistance, and immune escape. These insights can guide the development of innovative diagnostic markers, therapeutic strategies, and prognostic indicators. Overall, this review provides a comprehensive summary of the diverse applications of single-cell sequencing in ovarian cancer. It encompasses the identification and characterization of novel cell subpopulations, the elucidation of tumor heterogeneity, the investigation of the tumor microenvironment, the analysis of mechanisms underlying metastasis, and the integration of innovative approaches such as organoid models and multi-omics analysis.

Genomic characterization of thymic epithelial tumors in a real-world dataset

BACKGROUND

Thymic epithelial tumors (TETs) are rare neoplasms arising in the mediastinum, including thymic carcinomas and thymomas. Due to their rarity, little is known about the genomic profiles of TETs. Herein, we investigated the genomic characteristics of TETs evaluated in a large comprehensive genomic profiling database in a real-world setting.

METHODS

We included data from two different cohorts: Foundation Medicine Inc. (FMI) in the United States and the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) in Japan. Samples profiled were examined for all classes of alterations in 253 genes targeted across all assays. Tumor mutational burden (TMB) and microsatellite instability (MSI) were also evaluated.

RESULTS

A total of 794 patients were collected in our study, including 722 cases from FMI and 72 cases from C-CAT. In the FMI data, CDKN2A (39.9%), TP53 (30.2%) and CDKN2B (24.6%) were frequently altered in thymic carcinoma, versus TP53 (7.8%), DNMT3A (6.8%), and CDKN2A (5.8%) in thymoma. TMB-high (≥10 mutations/Mb) and MSI were present in 7.0% and 2.3% of thymic carcinomas, and 1.6% and 0.3% of thymomas, respectively. Within C-CAT data, CDKN2A (38.5%), TP53 (36.5%) and CDKN2B (30.8%) were also frequently altered in thymic carcinoma, while alterations of TSC1, SETD2 and LTK (20.0% each) were found in thymoma.

CONCLUSIONS

To the best of our knowledge, this is the largest cohort in which genomic alterations, TMB and MSI status of TETs were investigated. Potential targets for treatment previously unbeknownst in TETs are identified in this study, entailing newfound opportunities to advance therapeutic development.

The clinical challenges of homologous recombination proficiency in ovarian cancer: from intrinsic resistance to new treatment opportunities

Ovarian cancer is the most lethal gynecologic cancer. Optimal cytoreductive surgery followed by platinum-based chemotherapy with or without bevacizumab is the conventional therapeutic strategy. Since 2016, the pharmacological treatment of epithelial ovarian cancer has significantly changed following the introduction of the poly (ADP-ribose) polymerase inhibitors (PARPi). BRCA1/2 mutations and homologous recombination deficiency (HRD) have been established as predictive biomarkers of the benefit from platinum-based chemotherapy and PARPi. While in the absence of HRD (the so-called homologous recombination proficiency, HRp), patients derive minimal benefit from PARPi, the use of the antiangiogenic agent bevacizumab in first line did not result in different efficacy according to the presence of homologous recombination repair (HRR) genes mutations. No clinical trials have currently compared PARPi and bevacizumab as maintenance therapy in the HRp population. Different strategies are under investigation to overcome primary and acquired resistance to PARPi and to increase the sensitivity of HRp tumors to these agents. These tumors are characterized by frequent amplifications of Cyclin E and MYC, resulting in high replication stress. Different agents targeting DNA replication stress, such as ATR, WEE1 and CHK1 inhibitors, are currently being explored in preclinical models and clinical trials and have shown promising preliminary signs of activity. In this review, we will summarize the available evidence on the activity of PARPi in HRp tumors and the ongoing research to develop new treatment options in this hard-to-treat population.

The evolving role of DNA damage response in overcoming therapeutic resistance in ovarian cancer

Epithelial ovarian cancer (EOC) is treated in the first-line setting with combined platinum and taxane chemotherapy, often followed by a maintenance poly (ADP-ribose) polymerase inhibitor (PARPi). Responses to first-line treatment are frequent. For many patients, however, responses are suboptimal or short-lived. Over the last several years, multiple new classes of agents targeting DNA damage response (DDR) mechanisms have advanced through clinical development. In this review, we explore the preclinical rationale for the use of ATR inhibitors, CHK1 inhibitors, and WEE1 inhibitors, emphasizing their application to chemotherapy-resistant and PARPi-resistant ovarian cancer. We also present an overview of the clinical development of the leading drugs in each of these classes, emphasizing the rationale for monotherapy and combination therapy approaches.

WEE1 inhibitor adavosertib in combination with carboplatin in advanced TP53 mutated ovarian cancer: A biomarker-enriched phase II study

OBJECTIVE

In the first part of this phase II study (NCT01164995), the combination of carboplatin and adavosertib (AZD1775) was shown to be safe and effective in patients with TP53 mutated platinum-resistant ovarian cancer (PROC). Here, we present the results of an additional safety and efficacy cohort and explore predictive biomarkers for resistance and response to this combination treatment.

METHODS

This is a phase II, open-label, non-randomized study. Patients with TP53 mutated PROC received carboplatin AUC 5 mg/ ml·min intravenously and adavosertib 225 mg BID orally for 2.5 days in a 21-day cycle. The primary objective is to determine the efficacy and safety of carboplatin and adavosertib. Secondary objectives include progression-free survival (PFS), changes in circulating tumor cells (CTC) and exploration of genomic alterations.

RESULTS

Thirty-two patients with a median age of 63 years (39-77 years) were enrolled and received treatment. Twenty-nine patients were evaluable for efficacy. Bone marrow toxicity, nausea and vomiting were the most common adverse events. Twelve patients showed partial response (PR) as best response, resulting in an objective ORR of 41% in the evaluable patients (95% CI: 23%-61%). The median PFS was 5.6 months (95% CI: 3.8-10.3). In patients with tumors harboring CCNE1 amplification, treatment efficacy was slightly but not significantly better.

CONCLUSIONS

Adavosertib 225 mg BID for 2.5 days and carboplatin AUC 5 could be safely combined and showed anti-tumor efficacy in patients with PROC. However, bone marrow toxicity remains a point of concern, since this is the most common reason for dose reductions and dose delays.

Could Inhibiting the DNA Damage Repair Checkpoint Rescue Immune-Checkpoint-Inhibitor-Resistant Endometrial Cancer?

Endometrial cancer (EC) is increasingly undermining female health worldwide, with poor survival rates for advanced or recurrent/metastatic diseases. The application of immune checkpoint inhibitors (ICIs) has opened a window of opportunity for patients with first-line therapy failure. However, there is a subset of patients with endometrial cancer who remain insensitive to immunotherapy alone. Therefore, it is necessary to develop new therapeutic agents and further explore reliable combinational strategies to optimize the efficacy of immunotherapy. DNA damage repair (DDR) inhibitors as novel targeted drugs are able to generate genomic toxicity and induce cell death in solid tumors, including EC. Recently, growing evidence has demonstrated the DDR pathway modulates innate and adaptive immunity in tumors. In this review, we concentrate on the exploration of the intrinsic correlation between DDR pathways, especially the ATM-CHK2-P53 pathway and the ATR-CHK1-WEE1 pathway, and oncologic immune response, as well as the feasibility of adding DDR inhibitors to ICIs for the treatment of patients with advanced or recurrent/metastatic EC. We hope that this review will offer some beneficial references to the investigation of immunotherapy and provide a reasonable basis for "double-checkpoint inhibition" in EC.

Multicenter Phase II Trial of the WEE1 Inhibitor Adavosertib in Refractory Solid Tumors Harboring CCNE1 Amplification

PURPOSE

Preclinical cancer models harboring CCNE1 amplification were more sensitive to adavosertib treatment, a WEE1 kinase inhibitor, than models without amplification. Thus, we conducted this phase II study to assess the antitumor activity of adavosertib in patients with CCNE1-amplified, advanced refractory solid tumors.

PATIENTS AND METHODS

Patients aged ≥ 18 years with measurable disease and refractory solid tumors harboring CCNE1 amplification, an Eastern Cooperative Oncology Group performance status of 0-1, and adequate organ function were studied. Patients received 300 mg of adavosertib once daily on days 1 through 5 and 8 through 12 of a 21-day cycle. The trial followed Bayesian optimal phase II design. The primary end point was objective response rate (ORR).

RESULTS

Thirty patients were enrolled. The median follow-up duration was 9.9 months. Eight patients had partial responses (PRs), and three had stable disease (SD) ≥ 6 months, with an ORR of 27% (95% CI, 12 to 46), a SD ≥ 6 months/PR rate of 37% (95% CI, 20 to 56), a median progression-free survival duration of 4.1 months (95% CI, 1.8 to 6.4), and a median overall survival duration of 9.9 months (95% CI, 4.8 to 15). Fourteen patients with epithelial ovarian cancer showed an ORR of 36% (95% CI, 13 to 65) and SD ≥ 6 months/PR of 57% (95% CI, 29 to 82), a median progression-free survival duration of 6.3 months (95% CI, 2.4 to 10.2), and a median overall survival duration of 14.9 months (95% CI, 8.9 to 20.9). Common treatment-related toxicities were GI, hematologic toxicities, and fatigue.

CONCLUSION

Adavosertib monotherapy demonstrates a manageable toxicity profile and promising clinical activity in refractory solid tumors harboring CCNE1 amplification, especially in epithelial ovarian cancer. Further study of adavosertib, alone or in combination with other therapeutic agents, in CCNE1-amplified epithelial ovarian cancer is warranted.

Clinical development of WEE1 inhibitors in gynecological cancers: A systematic review

INTRODUCTION

The anti-tumor activity of WEE1 inhibitors (WEE1i) in gynecological malignancies has recently been demonstrated in clinical trials and its rationale is based on biological/molecular features of gynecological cancers. With this systematic review, we aim to outline the clinical development and current evidence regarding the efficacy and safety of these targeted agents in in this patient group.

METHODS

Systematic literature review of trials including patients with gynecological cancers treated with a WEE1i. The primary objective was to summarize the efficacy of WEE1i in gynecological malignancies regarding objective response rate (ORR), clinical benefit rate (CBR), overall survival (OS) and progression-free survival (PFS). Secondary objectives included toxicity profile, Maximum Tolerated Dose (MTD), pharmacokinetics, drug-drug interactions and exploratory objectives such as biomarkers for response.

RESULTS

26 records were included for data extraction. Almost all trials used the first-in-class WEE1i adavosertib; one conference abstract reported about Zn-c3. The majority of the trials included diverse solid tumors (n = 16). Six records reported efficacy results of WEE1i in gynecological malignancies (n = 6). Objective response rates of adavosertib monotherapy or in combination with chemotherapy ranged between 23% and 43% in these trials. Median PFS ranged from 3.0 to 9.9 months. The most common adverse events were bone marrow suppression, gastrointestinal toxicities and fatigue. Mainly alterations in cell cycle regulator genes TP53 and CCNE1 were potential predictors of response.

CONCLUSION

This report summarizes encouraging clinical development of WEE1i in gynecological cancers and considers its application in future studies. Biomarker-driven patient selection might be essential to increase the response rates.

Combined Inhibition of IAPs and WEE1 Enhances TNFα- and Radiation-Induced Cell Death in Head and Neck Squamous Carcinoma

Head and neck squamous cell carcinoma (HNSCC) remains a prevalent diagnosis with current treatment options that include radiotherapy and immune-mediated therapies, in which tumor necrosis factor-α (TNFα) is a key mediator of cytotoxicity. However, HNSCC and other cancers often display TNFα resistance due to activation of the canonical IKK-NFκB/RELA pathway, which is activated by, and induces expression of, cellular inhibitors of apoptosis proteins (cIAPs). Our previous studies have demonstrated that the IAP inhibitor birinapant sensitized HNSCC to TNFα-dependent cell death in vitro and radiotherapy in vivo. Furthermore, we recently demonstrated that the inhibition of the G2/M checkpoint kinase WEE1 also sensitized HNSCC cells to TNFα-dependent cell death, due to the inhibition of the pro-survival IKK-NFκB/RELA complex. Given these observations, we hypothesized that dual-antagonist therapy targeting both IAP and WEE1 proteins may have the potential to synergistically sensitize HNSCC to TNFα-dependent cell death. Using the IAP inhibitor birinapant and the WEE1 inhibitor AZD1775, we show that combination treatment reduced cell viability, proliferation and survival when compared with individual treatment. Furthermore, combination treatment enhanced the sensitivity of HNSCC cells to TNFα-induced cytotoxicity via the induction of apoptosis and DNA damage. Additionally, birinapant and AZD1775 combination treatment decreased cell proliferation and survival in combination with radiotherapy, a critical source of TNFα. These results support further investigation of IAP and WEE1 inhibitor combinations in preclinical and clinical studies in HNSCC.

ODF2L acts as a synthetic lethal partner with WEE1 inhibition in epithelial ovarian cancer models

WEE1 has emerged as an attractive target in epithelial ovarian cancer (EOC), but how EOC cells may alter their sensitivity to WEE1 inhibition remains unclear. Here, through a cell cycle machinery-related gene RNAi screen, we found that targeting outer dense fiber of sperm tails 2-like (ODF2L) was a synthetic lethal partner with WEE1 kinase inhibition in EOC cells. Knockdown of ODF2L robustly sensitized cells to treatment with the WEE1 inhibitor AZD1775 in EOC cell lines in vitro as well as in xenografts in vivo. Mechanistically, the increased sensitivity to WEE1 inhibition upon ODF2L loss was accompanied by accumulated DNA damage. ODF2L licensed the recruitment of PKMYT1, a functionally redundant kinase of WEE1, to the CDK1-cyclin B complex and thus restricted the activity of CDK1 when WEE1 was inhibited. Clinically, upregulation of ODF2L correlated with CDK1 activity, DNA damage levels, and sensitivity to WEE1 inhibition in patient-derived EOC cells. Moreover, ODF2L levels predicted the response to WEE1 inhibition in an EOC patient-derived xenograft model. Combination treatment with tumor-targeted lipid nanoparticles that packaged ODF2L siRNA and AZD1775 led to the synergistic attenuation of tumor growth in the ID8 ovarian cancer syngeneic mouse model. These data suggest that WEE1 inhibition is a promising precision therapeutic strategy for EOC cells expressing low levels of ODF2L.

DNA Damage Response Alterations in Ovarian Cancer: From Molecular Mechanisms to Therapeutic Opportunities

The DNA damage response (DDR), a set of signaling pathways for DNA damage detection and repair, maintains genomic stability when cells are exposed to endogenous or exogenous DNA-damaging agents. Alterations in these pathways are strongly associated with cancer development, including ovarian cancer (OC), the most lethal gynecologic malignancy. In OC, failures in the DDR have been related not only to the onset but also to progression and chemoresistance. It is known that approximately half of the most frequent subtype, high-grade serous carcinoma (HGSC), exhibit defects in DNA double-strand break (DSB) repair by homologous recombination (HR), and current evidence indicates that probably all HGSCs harbor a defect in at least one DDR pathway. These defects are not restricted to HGSCs; mutations in ARID1A, which are present in 30% of endometrioid OCs and 50% of clear cell (CC) carcinomas, have also been found to confer deficiencies in DNA repair. Moreover, DDR alterations have been described in a variable percentage of the different OC subtypes. Here, we overview the main DNA repair pathways involved in the maintenance of genome stability and their deregulation in OC. We also recapitulate the preclinical and clinical data supporting the potential of targeting the DDR to fight the disease.

Drugs Targeting p53 Mutations with FDA Approval and in Clinical Trials

Mutations in the tumor suppressor p53 (p53) promote cancer progression. This is mainly due to loss of function (LOS) as a tumor suppressor, dominant-negative (DN) activities of missense mutant p53 (mutp53) over wild-type p53 (wtp53), and wtp53-independent oncogenic activities of missense mutp53 by interacting with other tumor suppressors or oncogenes (gain of function: GOF). Since p53 mutations occur in ~50% of human cancers and rarely occur in normal tissues, p53 mutations are cancer-specific and ideal therapeutic targets. Approaches to target p53 mutations include (1) restoration or stabilization of wtp53 conformation from missense mutp53, (2) rescue of p53 nonsense mutations, (3) depletion or degradation of mutp53 proteins, and (4) induction of p53 synthetic lethality or targeting of vulnerabilities imposed by p53 mutations (enhanced YAP/TAZ activities) or deletions (hyperactivated retrotransposons). This review article focuses on clinically available FDA-approved drugs and drugs in clinical trials that target p53 mutations and summarizes their mechanisms of action and activities to suppress cancer progression.

Targeting replication stress in cancer therapy

Replication stress is a major cause of genomic instability and a crucial vulnerability of cancer cells. This vulnerability can be therapeutically targeted by inhibiting kinases that coordinate the DNA damage response with cell cycle control, including ATR, CHK1, WEE1 and MYT1 checkpoint kinases. In addition, inhibiting the DNA damage response releases DNA fragments into the cytoplasm, eliciting an innate immune response. Therefore, several ATR, CHK1, WEE1 and MYT1 inhibitors are undergoing clinical evaluation as monotherapies or in combination with chemotherapy, poly[ADP-ribose]polymerase (PARP) inhibitors, or immune checkpoint inhibitors to capitalize on high replication stress, overcome therapeutic resistance and promote effective antitumour immunity. Here, we review current and emerging approaches for targeting replication stress in cancer, from preclinical and biomarker development to clinical trial evaluation.

A targetable MYBL2-ATAD2 axis governs cell proliferation in ovarian cancer

The chromatin-modifying enzyme ATAD2 confers oncogenic competence and proliferative advantage in malignances. We previously identified ATAD2 as a marker and driver of cell proliferation in ovarian cancer (OC); however, the mechanisms whereby ATAD2 is regulated and involved in cell proliferation are still unclear. Here, we disclose that ATAD2 displays a classical G2/M gene signature, functioning to facilitate mitotic progression. ATAD2 ablation caused mitotic arrest and decreased the ability of OC cells to pass through nocodazole-arrested mitosis. ChIP-seq data analyses demonstrated that DREAM and MYBL2-MuvB (MMB), two switchable MuvB-based complexes, bind the CHR elements in the ATAD2 promoter, representing a typical feature and principle mechanism of the periodic regulation of G2/M genes. As a downstream target of MYBL2, ATAD2 deletion significantly impaired MYBL2-driven cell proliferation. Intriguingly, ATAD2 silencing also fed back to destabilize the MYBL2 protein. The significant coexpression of MYBL2 and ATAD2 at both the bulk tissue and single-cell levels highlights the existence of the MYBL2-ATAD2 signaling in OC patients. This signaling is activated during tumorigenesis and correlated with TP53 mutation, and its hyperactivation was found especially in high-grade serous and drug-resistant OCs. Disrupting this signaling by CRISPR/Cas9-mediated ATAD2 ablation inhibited the in vivo growth of OC in a subcutaneous tumor xenograft mouse model, while pharmacologically targeting this signaling with an ATAD2 inhibitor demonstrated high therapeutic efficacy in both drug-sensitive and drug-resistant OC cells. Collectively, we identified a novel MYBL2-ATAD2 proliferative signaling axis and highlighted its potential application in developing new therapeutic strategies, especially for high-grade serous and drug-resistant OCs.

Kinase Inhibitors in the Treatment of Ovarian Cancer: Current State and Future Promises

Ovarian cancer is the deadliest gynecological cancer, the high-grade serous ovarian carcinoma (HGSC) being its most common and most aggressive form. Despite the latest therapeutical advancements following the introduction of vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors and poly-ADP-ribose-polymerase (PARP) inhibitors to supplement the standard platinum- and taxane-based chemotherapy, the expected overall survival of HGSC patients has not improved significantly from the five-year rate of 42%. This calls for the development and testing of more efficient treatment options. Many oncogenic kinase-signaling pathways are dysregulated in HGSC. Since small-molecule kinase inhibitors have revolutionized the treatment of many solid cancers due to the generality of the increased activation of protein kinases in carcinomas, it is reasonable to evaluate their potential against HGSC. Here, we present the latest concluded and on-going clinical trials on kinase inhibitors in HGSC, as well as the recent work concerning ovarian cancer patient organoids and xenograft models. We discuss the potential of kinase inhibitors as personalized treatments, which would require comprehensive assessment of the biological mechanisms underlying tumor spread and chemoresistance in individual patients, and their connection to tumor genome and transcriptome to establish identifiable subgroups of patients who are most likely to benefit from a given therapy.

Evolving DNA repair synthetic lethality targets in cancer

DNA damage signaling response and repair (DDR) is a critical defense mechanism against genomic instability. Impaired DNA repair capacity is an important risk factor for cancer development. On the other hand, up-regulation of DDR mechanisms is a feature of cancer chemotherapy and radiotherapy resistance. Advances in our understanding of DDR and its complex role in cancer has led to several translational DNA repair-targeted investigations culminating in clinically viable precision oncology strategy using poly(ADP-ribose) polymerase (PARP) inhibitors in breast, ovarian, pancreatic, and prostate cancers. While PARP directed synthetic lethality has improved outcomes for many patients, the lack of sustained clinical response and the development of resistance pose significant clinical challenges. Therefore, the search for additional DDR-directed drug targets and novel synthetic lethality approaches is highly desirable and is an area of intense preclinical and clinical investigation. Here, we provide an overview of the mammalian DNA repair pathways and then focus on current state of PARP inhibitors (PARPi) and other emerging DNA repair inhibitors for synthetic lethality in cancer.

Resistance to Poly (ADP-Ribose) Polymerase Inhibitors (PARPi): Mechanisms and Potential to Reverse

PURPOSE OF REVIEW

This review will focus on the most common mechanisms for poly (ADP-ribose) polymerase inhibitors' (PARPi) resistance and the main strategies for overcoming acquired or de novo PARPi resistance.

RECENT FINDINGS

Initial approvals for PARPi as part of treatment for advanced epithelial ovarian cancer (EOC) started in 2014 with patient with recurrent cancer characterized by BRCA mutations in the 3rd and 4th line and now have approvals for front-line maintenance in both the BRCA mutated and BRCAwt populations. As with all therapies, patients will eventually develop resistance to treatment. The most common mechanisms for PARPi resistance include reversion mutations, methylation events, and restoration of homologous recombination deficiency (HRD) through combinations and targeting replication stress. As more and more patients receive initial treatment (and potential retreatment with PARPi), we need to better understand the mechanisms in which tumors acquire PARPi resistance.

Experimental drugs for fallopian cancer: promising agents in the clinical trials and key stumbling blocks for researchers

INTRODUCTION

Fallopian tube carcinoma (FC) as a single entity is a rare disease. Although its diagnosis is increasing thanks to the widespread use of prophylactic salpingectomy, there are no clinical trials exclusively designed for FC.

AREAS COVERED

This review aims at identifying the most promising trials and future therapeutic pathways in the setting of FC.

EXPERT OPINION

Hot topics in FC treatment include the consequences of using PARP inhibitors (PARPi) as first-line therapy, ways to overcome platinum resistance, and the role of immunotherapy. Patient selection is a key point for future development of target therapies. Next-generation sequencing (NGS) is one of the most investigated technologies both for drug discovery and identification of reverse mutations, involved in resistance to PARPi and platinum. New, promising molecular targets are emerging. Notwithstanding the disappointing outcomes when used by itself, immunotherapy in FC treatment could still have a role in combination with other agents, exploiting synergistic effects at the molecular level. The development of cancer vaccines is currently hampered by the high variability of tumor neoantigens in FC. Genomic profiling could be a solution, allowing the synthesis of individualized vaccines.

Splicing factor BUD31 promotes ovarian cancer progression through sustaining the expression of anti-apoptotic BCL2L12

Dysregulated expression of splicing factors has important roles in cancer development and progression. However, it remains a challenge to identify the cancer-specific splicing variants. Here we demonstrate that spliceosome component BUD31 is increased in ovarian cancer, and its higher expression predicts worse prognosis. We characterize the BUD31-binding motif and find that BUD31 preferentially binds exon-intron regions near splicing sites. Further analysis reveals that BUD31 inhibition results in extensive exon skipping and a reduced production of long isoforms containing full coding sequence. In particular, we identify BCL2L12, an anti-apoptotic BCL2 family member, as one of the functional splicing targets of BUD31. BUD31 stimulates the inclusion of exon 3 to generate full-length BCL2L12 and promotes ovarian cancer progression. Knockdown of BUD31 or splice-switching antisense oligonucleotide treatment promotes exon 3 skipping and results in a truncated isoform of BCL2L12 that undergoes nonsense-mediated mRNA decay, and the cells subsequently undergo apoptosis. Our findings reveal BUD31-regulated exon inclusion as a critical factor for ovarian cancer cell survival and cancer progression.

State of the Biomarker Science in Ovarian Cancer: A National Cancer Institute Clinical Trials Planning Meeting Report

PURPOSE

Despite therapeutic advances in the treatment of ovarian cancer (OC), 5-year survival remains low, and patients eventually die from recurrent, chemotherapy-resistant disease. The National Cancer Gynecologic Cancer Steering Committee identified the integration of scientifically defined subgroups as a top strategic priority in clinical trial planning.

METHODS

A group of experts was convened to review the scientific literature in OC to identify validated predictive biomarkers that could inform patient selection and treatment stratification. Here, we report on these findings and their potential for use in future clinical trial design on the basis of hierarchal evidence grading.

RESULTS

The biomarkers were classified on the basis of mechanistic targeting, including DNA repair and replication stress, immunotherapy and tumor microenvironment, oncogenic signaling, and angiogenesis. Currently, BRCA mutations and homologous recombination deficiency to predict poly (ADP-ribose) polymerase inhibitor response are supported in OC by the highest level of evidence. Additional biomarkers of response to agents targeting the pathways above have been identified but require prospective validation.

CONCLUSION

Although a number of biomarkers of response to various agents in OC have been described in the literature, high-level evidence for the majority is lacking. This report highlights the unmet need for identification and validation of predictive biomarkers to guide therapy and future trial design in OC.

Mitotic Checkpoints and the Role of WEE1 Inhibition in Head and Neck Squamous Cell Carcinoma

ABSTRACT

The WEE1 kinase family plays a crucial role in cell cycle regulation and DNA damage response pathways in malignant cells. Inhibition of WEE1 effectively overrides G2 cell cycle arrest and results in the accumulation of extensive DNA damage within dividing cells, potentiating mitotic catastrophe and cell death. As such, the development of WEE1 inhibitors as antineoplastic therapeutics has gained increasing interest in recent years. In particular, the role of WEE1 inhibitors for treatment of head and neck squamous cell carcinomas remains an area of active research with both preclinical and clinical studies investigating their use as both single-agent therapy and chemosensitizers when used in tandem with traditional chemotherapy, particularly in the context of TP53-mutant tumors. Here, we review the relevant available preclinical and clinical data on hand investigating the efficacy of WEE1 inhibitors for the treatment of head and neck cancers.

Targeting the DNA damage response beyond poly(ADP-ribose) polymerase inhibitors: novel agents and rational combinations

PURPOSE OF REVIEW

Poly(ADP-ribose) polymerase (PARP) inhibitors have transformed treatment paradigms in multiple cancer types defined by homologous recombination deficiency (HRD) and have become the archetypal example of synthetic lethal targeting within the DNA damage response (DDR). Despite this success, primary and acquired resistance to PARP inhibition inevitability threaten the efficacy and durability of response to these drugs. Beyond PARP inhibitors, recent advances in large-scale functional genomic screens have led to the identification of a steadily growing list of genetic dependencies across the DDR landscape. This has led to a wide array of novel synthetic lethal targets and corresponding inhibitors, which hold promise to widen the application of DDR inhibitors beyond HRD and potentially address PARP inhibitor resistance.

RECENT FINDINGS

In this review, we describe key synthetic lethal interactions that have been identified across the DDR landscape, summarize the early phase clinical development of the most promising DDR inhibitors, and highlight relevant combinations of DDR inhibitors with chemotherapy and other novel cancer therapies, which are anticipated to make an impact in rationally selected patient populations.

SUMMARY

The DDR landscape holds multiple opportunities for synthetic lethal targeting with multiple novel DDR inhibitors being evaluated on early phase clinical trials. Key challenges remain in optimizing the therapeutic window of ATR and WEE1 inhibitors as monotherapy and in combination approaches.

Targeting Replication Stress Response Pathways to Enhance Genotoxic Chemo- and Radiotherapy

Proliferating cells regularly experience replication stress caused by spontaneous DNA damage that results from endogenous reactive oxygen species (ROS), DNA sequences that can assume secondary and tertiary structures, and collisions between opposing transcription and replication machineries. Cancer cells face additional replication stress, including oncogenic stress that results from the dysregulation of fork progression and origin firing, and from DNA damage induced by radiotherapy and most cancer chemotherapeutic agents. Cells respond to such stress by activating a complex network of sensor, signaling and effector pathways that protect genome integrity. These responses include slowing or stopping active replication forks, protecting stalled replication forks from collapse, preventing late origin replication firing, stimulating DNA repair pathways that promote the repair and restart of stalled or collapsed replication forks, and activating dormant origins to rescue adjacent stressed forks. Currently, most cancer patients are treated with genotoxic chemotherapeutics and/or ionizing radiation, and cancer cells can gain resistance to the resulting replication stress by activating pro-survival replication stress pathways. Thus, there has been substantial effort to develop small molecule inhibitors of key replication stress proteins to enhance tumor cell killing by these agents. Replication stress targets include ATR, the master kinase that regulates both normal replication and replication stress responses; the downstream signaling kinase Chk1; nucleases that process stressed replication forks (MUS81, EEPD1, Metnase); the homologous recombination catalyst RAD51; and other factors including ATM, DNA-PKcs, and PARP1. This review provides an overview of replication stress response pathways and discusses recent pre-clinical studies and clinical trials aimed at improving cancer therapy by targeting replication stress response factors.

Inhibiting the IRE1α Axis of the Unfolded Protein Response Enhances the Antitumor Effect of AZD1775 in TP53 Mutant Ovarian Cancer

Targeting the G2/M checkpoint mediator WEE1 has been explored as a novel treatment strategy in ovarian cancer, but mechanisms underlying its efficacy and resistance remains to be understood. Here, it is demonstrated that the WEE1 inhibitor AZD1775 induces endoplasmic reticulum stress and activates the protein kinase RNA-like ER kinase (PERK) and inositol-required enzyme 1α (IRE1α) branches of the unfolded protein response (UPR) in TP53 mutant (mtTP53) ovarian cancer models. This is facilitated through NF-κB mediated senescence-associated secretory phenotype. Upon AZD1775 treatment, activated PERK promotes apoptotic signaling via C/EBP-homologous protein (CHOP), while IRE1α-induced splicing of XBP1 (XBP1s) maintains cell survival by repressing apoptosis. This leads to an encouraging synergistic antitumor effect of combining AZD1775 and an IRE1α inhibitor MKC8866 in multiple cell lines and preclinical models of ovarian cancers. Taken together, the data reveal an important dual role of the UPR signaling network in mtTP53 ovarian cancer models in response to AZD1775 and suggest that inhibition of the IRE1α-XBP1s pathway may enhance the efficacy of AZD1775 in the clinics.

Efficacy and Safety of Placebo During the Maintenance Therapy of Ovarian Cancer in Randomized Controlled Trials: A Systematic Review and Meta-analysis

Introduction

This meta-analysis evaluated the efficacy and safety of placebo during the maintenance therapy of ovarian cancer (OC) patients in randomized controlled trials (RCTs).

Methods

A comprehensive literature review was performed for RCTs published up to and including August 2020 from four electronic databases. We analyzed the efficacy and safety in the control arms of the maintenance therapy in advanced OC patients. Hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) of progression-free survival (PFS) and overall survival (OS) were estimated in the placebo arms and the observation arms, respectively, using the Frequency Framework method. We also calculated the incidences of common adverse effects (AEs) in the placebo arms.

Results

In total, 41 articles with 20,099 (4,787 in the placebo arms, 3,420 in the observation arms, and 11,892 in the experiment arms) patients were included in this meta-analysis. Compared with observation, placebo did not improve or reduce PFS (HR, 1.02; 95% CI, 0.87–1.20; P = 0.81) and OS (HR, 1.02; 95% CI, 0.89–1.16; P = 0.76) of OC patients, while other treatments, except for radiotherapy, significantly improved PFS and OS (all P < 0.05). The incidences of AEs produced by placebo were 94.03% in all grades and 20.22% in grade ≥3. The incidences of AEs were 29.75% in fatigue, 26.38% in nausea, 24.34% in abdominal pain, 18.92% in constipation, 16.65% in diarrhea, 14.55% in vomiting, 13.89% in hypertension, and 13.14% in headache.

Conclusions

Placebo did not improve or reduce the PFS and OS benefits of OC patients in RCTs but increased the incidences of AEs.

WEE1 inhibition enhances the antitumor immune response to PD-L1 blockade by the concomitant activation of STING and STAT1 pathways in SCLC

Small cell lung cancers (SCLCs) have high mutational burden but are relatively unresponsive to immune checkpoint blockade (ICB). Using SCLC models, we demonstrate that inhibition of WEE1, a G2/M checkpoint regulator induced by DNA damage, activates the STING-TBK1-IRF3 pathway, which increases type I interferons (IFN-α and IFN-β) and pro-inflammatory chemokines (CXCL10 and CCL5), facilitating an immune response via CD8⁺ cytotoxic T cell infiltration. We further show that WEE1 inhibition concomitantly activates the STAT1 pathway, increasing IFN-γ and PD-L1 expression. Consistent with these findings, combined WEE1 inhibition (AZD1775) and PD-L1 blockade causes remarkable tumor regression, activation of type I and II interferon pathways, and infiltration of cytotoxic T cells in multiple immunocompetent SCLC genetically engineered mouse models, including an aggressive model with stabilized MYC. Our study demonstrates cell-autonomous and immune-stimulating activity of WEE1 inhibition in SCLC models. Combined inhibition of WEE1 plus PD-L1 blockade represents a promising immunotherapeutic approach in SCLC.

Advanced Strategies for Therapeutic Targeting of Wild-Type and Mutant p53 in Cancer

TP53 is a tumor suppressor gene that encodes a sequence-specific DNA-binding transcription factor activated by stressful stimuli; it upregulates target genes involved in growth suppression, cell death, DNA repair, metabolism, among others. TP53 is the most frequently mutated gene in tumors, with mutations not only leading to loss-of-function (LOF), but also gain-of-function (GOF) that promotes tumor progression, and metastasis. The tumor-specific status of mutant p53 protein has suggested it is a promising target for cancer therapy. We summarize the current progress of targeting wild-type and mutant p53 for cancer therapy through biotherapeutic and biopharmaceutical methods for (1) boosting p53 activity in cancer, (2) p53-dependent and p53-independent strategies for targeting p53 pathway functional restoration in p53-mutated cancer, (3) targeting p53 in immunotherapy, and (4) combination therapies targeting p53, p53 checkpoints, or mutant p53 for cancer therapy.

Ricolinostat enhances adavosertib‑induced mitotic catastrophe in TP53‑mutated head and neck squamous cell carcinoma cells

TP53 mutation is one of the most frequent gene mutations in head and neck squamous cell carcinoma (HNSCC) and could be a potential therapeutic target. Recently, the WEE1 G2 checkpoint kinase (WEE1) inhibitor adavosertib (Adv) has attracted attention because of its selective cytotoxicity against TP53-mutated cells and has shown promising activity in early phase clinical trials. In the present study, it was demonstrated that combined treatment with Adv and a selective histone deacetylase 6 (HDAC6) inhibitor, ricolinostat (RCS), synergistically enhanced cell death induction in four out of five HNSCC cell lines with TP53 mutation (CAL27, SAS, HSC-3, and OSC-19), one HNSCC cell line with impaired TP53 function by HPV-infection (UPCI-SCC154), and TP53-knockout human lung cancer cell line (A549 TP53-KO), but not in TP53 wild-type A549 cells. Time-lapse imaging showed that RCS enhanced the Adv-induced mitotic catastrophe. Consistent with this, RCS treatment suppressed checkpoint kinase 1 (Chk1) (Ser345) phosphorylation and co-administration of RCS with Adv suppressed cyclin-dependent kinase 1 (Tyr15) phosphorylation along with increased expression of γ-H2A.X, a marker of DNA double-strand breaks in CAL27 cells. These data showed that RCS enhanced Adv-induced premature mitotic entry and cell death induction in the mitotic phase. However, although HDAC6 knockdown enhanced Adv-induced cell death with γ-H2A.X elevation, HDAC6 knockdown did not repress Chk1 phosphorylation in CAL27 cells. Our data demonstrated that the co-administration of RCS with Adv in HNSCC cells resulted in the suppression of Chk1 activity, leading to synergistically enhanced apoptosis via mitotic catastrophe in a p53-dependent manner. This enhanced cell death appeared to be partially mediated by the inhibition of HDAC6 activity by RCS.

WEE1 kinase is a therapeutic vulnerability in CIC-DUX4 undifferentiated sarcoma

CIC-DUX4 rearrangements define an aggressive and chemotherapy-insensitive subset of undifferentiated sarcomas. The CIC-DUX4 fusion drives oncogenesis through direct transcriptional upregulation of cell cycle and DNA replication genes. Notably, CIC-DUX4–mediated CCNE1 upregulation compromises the G₁/S transition to confer a dependence on the G₂/M cell cycle checkpoint. Through an integrative transcriptional and kinase activity screen using patient-derived specimens, we now show that CIC-DUX4 sarcomas depend on the G₂/M checkpoint regulator WEE1 as part of an adaptive survival mechanism. Specifically, CIC-DUX4 sarcomas depended on WEE1 activity to limit DNA damage and unscheduled mitotic entry. Consequently, genetic or pharmacologic WEE1 inhibition in vitro and in vivo led to rapid DNA damage–associated apoptotic induction of patient-derived CIC-DUX4 sarcomas. Thus, we identified WEE1 as a vulnerability targetable by therapeutic intervention in CIC-DUX4 sarcomas.

Everything Comes with a Price: The Toxicity Profile of DNA-Damage Response Targeting Agents

Simple Summary

DNA damage induces genome instability, which may elicit cancer development. Defects in the DNA repair machinery further enhance cancer predisposition, but can also be exploited as a therapeutic target. Indeed, targeted agents against specific components of DNA repair, such as PARP inhibitors, are employed in various tumor types, while others, such as ATR, CHK1 or WEE1 inhibitors, are in clinical development. Even though these molecules have proven to be effective in different settings, they display several on- and off-target toxicities, shared by the whole pharmacological class or are drug specific. Among these effects, hematological and gastrointestinal toxicities are the most common, while others are less frequent but potentially life-threatening (e.g., myelodysplastic syndromes). Particular caution is needed in the case of combinatorial therapeutic approaches, which are currently being developed in clinical trials. In any case, it is necessary to recognize and properly manage adverse events of these drugs. This review provides a comprehensive overview on the safety profile of DDR-targeting agents, including indications for their management in clinical practice.

Abstract

Targeting the inherent vulnerability of cancer cells with an impaired DNA Damage Repair (DDR) machinery, Poly-ADP-Ribose-Polymerase (PARP) inhibitors have yielded significant results in several tumor types, eventually entering clinical practice for the treatment of ovarian, breast, pancreatic and prostate cancer. More recently, inhibitors of other key components of DNA repair, such as ATR, CHK1 and WEE1, have been developed and are currently under investigation in clinical trials. The inhibition of DDR inevitably induces on-target and off-target adverse events. Hematological and gastrointestinal toxicities as well as fatigue are common with all DDR-targeting agents, while other adverse events are drug specific, such as hypertension with niraparib and transaminase elevation with rucaparib. Cases of pneumonitis and secondary hematological malignancies have been reported with PARP inhibitors and, despite being overly rare, they deserve particular attention due to their severity. Safety also represents a crucial issue for the development of combination regimens incorporating DDR-targeting agents with other treatments, such as chemotherapy, anti-angiogenics or immunotherapy. As such, overlapping and cumulative toxicities should be considered, especially when more than two classes of drugs are combined. Here, we review the safety profile of DDR-targeting agents when used as single agents or in combination and we provide principles of toxicity management.

Therapeutic Targeting of DNA Damage Response in Cancer

DNA damage response (DDR) is critical to ensure genome stability, and defects in this signaling pathway are highly associated with carcinogenesis and tumor progression. Nevertheless, this also provides therapeutic opportunities, as cells with defective DDR signaling are directed to rely on compensatory survival pathways, and these vulnerabilities have been exploited for anticancer treatments. Following the impressive success of PARP inhibitors in the treatment of BRCA-mutated breast and ovarian cancers, extensive research has been conducted toward the development of pharmacologic inhibitors of the key components of the DDR signaling pathway. In this review, we discuss the key elements of the DDR pathway and how these molecular components may serve as anticancer treatment targets. We also summarize the recent promising developments in the field of DDR pathway inhibitors, focusing on novel agents beyond PARP inhibitors. Furthermore, we discuss biomarker studies to identify target patients expected to derive maximal clinical benefits as well as combination strategies with other classes of anticancer agents to synergize and optimize the clinical benefits.

Single-cell analysis revealed that IL4I1 promoted ovarian cancer progression

Background

Ovarian cancer was one of the leading causes of female deaths. Patients with OC were essentially incurable and portends a poor prognosis, presumably because of profound genetic heterogeneity limiting reproducible prognostic classifications.

Methods

We comprehensively analyzed an ovarian cancer single-cell RNA sequencing dataset, GSE118828, and identified nine major cell types. Relationship between the clusters was explored with CellPhoneDB. A malignant epithelial cluster was confirmed using pseudotime analysis, CNV and GSVA. Furthermore, we constructed the prediction model (i.e., RiskScore) consisted of 10 prognosis-specific genes from 2397 malignant epithelial genes using the LASSO Cox regression algorithm based on public datasets. Then, the prognostic value of Riskscore was assessed with Kaplan–Meier survival analysis and time-dependent ROC curves. At last, a series of in-vitro assays were conducted to explore the roles of IL4I1, an important gene in Riskscore, in OC progression.

Results

We found that macrophages possessed the most interaction pairs with other clusters, and M2-like TAMs were the dominant type of macrophages. C0 was identified as the malignant epithelial cluster. Patients with a lower RiskScore had a greater OS (log-rank P < 0.01). In training set, the AUC of RiskScore was 0.666, 0.743 and 0.809 in 1-year, 3-year and 5-year survival, respectively. This was also validated in another two cohorts. Moreover, downregulation of IL4I1 inhibited OC cells proliferation, migration and invasion.

Conclusions

Our work provide novel insights into our understanding of the heterogeneity among OCs, and would help elucidate the biology of OC and provide clinical guidance in prognosis for OC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03123-7.

Adavosertib with Chemotherapy in Patients with Primary Platinum-Resistant Ovarian, Fallopian Tube, or Peritoneal Cancer: An Open-Label, Four-Arm, Phase II Study

PURPOSE

This study assessed the efficacy, safety, and pharmacokinetics of adavosertib in combination with four chemotherapy agents commonly used in patients with primary platinum-resistant ovarian cancer.

PATIENTS AND METHODS

Women with histologically or cytologically confirmed epithelial ovarian, fallopian tube, or peritoneal cancer with measurable disease were enrolled between January 2015 and January 2018 in this open-label, four-arm, multicenter, phase II study. Patients received adavosertib (oral capsules, 2 days on/5 days off or 3 days on/4 days off) in six cohorts from 175 mg once daily to 225 mg twice daily combined with gemcitabine, paclitaxel, carboplatin, or pegylated liposomal doxorubicin. The primary outcome measurement was overall response rate.

RESULTS

Three percent of patients (3/94) had confirmed complete response and 29% (27/94) had confirmed partial response. The response rate was highest with carboplatin plus weekly adavosertib, at 66.7%, with 100% disease control rate, and median progression-free survival of 12.0 months. The longest median duration of response was in the paclitaxel cohort (12.0 months). The most common grade ≥3 adverse events across all cohorts were neutropenia [45/94 (47.9%) patients], anemia [31/94 (33.0%)], thrombocytopenia [30/94 (31.9%)], and diarrhea and vomiting [10/94 (10.6%) each].

CONCLUSIONS

Adavosertib showed preliminary efficacy when combined with chemotherapy. The most promising treatment combination was adavosertib 225 mg twice daily on days 1-3, 8-10, and 15-17 plus carboplatin every 21 days. However, hematologic toxicity was more frequent than would be expected for carboplatin monotherapy, and the combination requires further study to optimize the dose, schedule, and supportive medications.

Emerging molecular alterations leading to histology-specific targeted therapies in ovarian cancer beyond PARP inhibitors

After more than 30 years of a one-size-fits-all approach in the management of advanced ovarian cancer, in 2018 the SOLO1 trial results have introduced a new era of personalized medicine. A deeper knowledge of ovarian cancer biology and the development of new drugs targeting specific molecular pathways have led to biomarker-driven phase 3 trials with practice changing results. Thereafter, platinum-based combinations are no longer the only therapeutic options available in first line setting and poly-ADP ribose polymerase inhibitors maintenance therapy has become the mainstay in patients with tumor harboring a homologous recombination defect. However, most of the recent therapeutic breakthroughs regard high grade serous carcinoma, the most frequent ovarian cancer subtype, and only few improvements have occurred in the management of less common histotypes. Moving towards the next challenges, we aimed to investigate and review new potential molecular targets in ovarian cancer, according to histotype, starting from promising molecular drivers and matched drugs that have been investigated in early and late-stage clinical trials or conceptualized in preclinical studies.

Development of New Cancer Treatment by Identifying and Focusing the Genetic Mutations or Altered Expression in Gynecologic Cancers

With the advent of next-generation sequencing (NGS), The Cancer Genome Atlas (TCGA) research network has given gynecologic cancers molecular classifications, which impacts clinical practice more and more. New cancer treatments that identify and target pathogenic abnormalities of genes have been in rapid development. The most prominent progress in gynecologic cancers is the clinical efficacy of poly(ADP-ribose) polymerase (PARP) inhibitors, which have shown breakthrough benefits in reducing hazard ratios (HRs) (HRs between 0.2 and 0.4) of progression or death from BRCA1/2 mutated ovarian cancer. Immune checkpoint inhibition is also promising in cancers that harbor mismatch repair deficiency (dMMR)/microsatellite instability (MSI). In this review, we focus on the druggable genetic alterations in gynecologic cancers by summarizing literature findings and completed and ongoing clinical trials.

Estrogens and the Schrödinger's Cat in the Ovarian Tumor Microenvironment

Simple Summary

Ovarian cancer is a complex pathology for which we require effective screening and therapeutical strategies. Apart from the cancer cell portion, there exist plastic immune and non-immune cell populations, jointly constituting the context-adaptive tumor microenvironment, which is pivotal in tumorigenesis. Estrogens might be synthesized in the ovarian tumor tissue and actively contribute to the shaping of an immunosuppressive microenvironment. Current immune therapies have limited effectiveness as a multitude of factors influence the outcome. A thorough understanding of the ovarian cancer biology is crucial in the efforts to reestablish homeostasis.

Abstract

Ovarian cancer is a heterogeneous disease affecting the aging ovary, in concert with a complex network of cells and signals, together representing the ovarian tumor microenvironment. As in the “Schrödinger’s cat” thought experiment, the context-dependent constituents of the—by the time of diagnosis—well-established tumor microenvironment may display a tumor-protective and -destructive role. Systemic and locally synthesized estrogens contribute to the formation of a pro-tumoral microenvironment that enables the sustained tumor growth, invasion and metastasis. Here we focus on the estrogen biosynthetic and metabolic pathways in ovarian cancer and elaborate their actions on phenotypically plastic, estrogen-responsive, aging immune cells of the tumor microenvironment, altogether highlighting the multicomponent-connectedness and complexity of cancer, and contributing to a broader understanding of the ovarian cancer biology.

Single-Cell RNA-Sequencing Portraying Functional Diversity and Clinical Implications of IFI6 in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies. Most patients die of metastasis due to a lack of other treatments aimed at improving the prognosis of OC patients. In the present study, we use multiple methods to identify prognostic S1 as the dominant subtype in OC, possessing the most ligand-receptor pairs with other cell types. Based on markers of S1, the consensus clustering algorithm is used to explore the clinical treatment subtype in OC. As a result, we identify two clusters associated with distinct survival and drug response. Notably, IFI6 contributes to the cluster classification and seems to be a vital gene in OC carcinogenesis. Functional enrichment analysis demonstrates that its functions involve G2M and cisplatin resistance, and downregulation of IFI6 suppresses proliferation capabilities and significantly potentiates cisplatin-induced apoptosis of OC cells in vitro. To explore possible mechanisms of IFI6 influencing OC proliferation and cisplatin resistance, GSEA is conducted and shows that IFI6 is positively correlated with the NF-κB pathway, which is validated by RT-qPCR. Significantly, we develop a prognostic model including IFI6, RiskScore, which is an independent prognostic factor and presents encouraging prognostic values. Our findings provide novel insights into elucidating the biology of OC based on single-cell RNA-sequencing. Moreover, this approach is potentially helpful for personalized anti-cancer strategies and predicting outcomes in the setting of OC.

WEE1 inhibitor and ataxia telangiectasia and RAD3-related inhibitor trigger stimulator of interferon gene-dependent immune response and enhance tumor treatment efficacy through programmed death-ligand 1 blockade

WEE1 plays an important role in the regulation of cell cycle G2/M checkpoints and DNA damage response (DDR). Inhibition of WEE1 can increase the instability of the genome and have anti–tumor effects in some solid tumors. However, it has certain limitations for multiple cancer cells from different lineages. Therefore, we consider the use of synthetic lethal interactions to enhance the therapeutic effect. Our experiments proved that WEE1 inhibitor (WEE1i) can activate the ataxia telangiectasia and RAD3‐related (ATR) pathway and that blockage of ATR dramatically sensitized the WEE1i‐induced cell death. The tumor‐selective synthetic lethality between bioavailable WEE1 and ATR inhibitors led to tumor remission in vivo. Mechanistically, the combination promoted the accumulation of cytosolic double‐strand DNA, which subsequently activated the stimulator of the interferon gene (STING) pathway and induced the production of type I interferon and CD8+ T cells, thereby inducing anti–tumor immunity. Furthermore, our study found that immune checkpoint programmed death‐ligand 1 is upregulated by the combination therapy, and blocking PD‐L1 further enhances the effect of the combination therapy. In summary, as an immunomodulator, the combination of WEE1i with ATR inhibitor (ATRi) and immune checkpoint blockers provides a potential new approach for cancer treatment.

WEE1 Inhibitor: Clinical Development

Purpose of Review

WEE1 inhibitor has been shown to potential chemotherapy or radiotherapy sensitivity in preclinical models, particularly in p53-mutated or deficient cancer cells although not exclusively. Here, we review the clinical development of WEE1 inhibitor in combination with chemotherapy or radiotherapy with concurrent chemotherapy as well as its combination with different novel agents.

Recent Findings

Although several clinical trials have shown that WEE1 inhibitor can be safely combined with different chemotherapy agents as well as radiotherapy with concurrent chemotherapy, its clinical development has been hampered by the higher rate of grade 3 toxicities when added to standard treatments. A few clinical trials had also been conducted to test WEE1 inhibitor using TP53 mutation as a predictive biomarker. However, TP53 mutation has not been shown to be the most reliable predictive biomarker and the benefit of adding WEE1 inhibitor to chemotherapy has been modest, even in TP53 biomarker-driven studies.

Summary

There are ongoing clinical trials testing WEE1 inhibitor with novel agents such as ATR and PAPR inhibitors as well as anti-PDL1 immunotherapy, which may better define the role of WEE1 inhibitor in the future if any of the novel treatment combination will show superior anti-tumor efficacy with a good safety profile compared to monotherapy and/or standard treatment.