The Clinicopathological Significance of the Cyclin D1/E1-Cyclin-Dependent Kinase (CDK2/4/6)-Retinoblastoma (RB1/pRB1) Pathway in Epithelial Ovarian Cancers

Cyclin-dependent kinases (CDK2, CDK4, CDK6), cyclin D1, cyclin E1 and phosphorylated retinoblastoma (pRB1) are key regulators of the G1/S cell cycle checkpoint and may influence platinum response in ovarian cancers. CDK2/4/6 inhibitors are emerging targets in ovarian cancer therapeutics. In the current study, we evaluated the prognostic and predictive significance of the CDK2/4/6-cyclin D1/E1-pRB1 axis in clinical ovarian cancers (OC). The CDK2/4/6, cyclin D1/E1 and RB1/pRB1 protein expression were investigated in 300 ovarian cancers and correlated with clinicopathological parameters and patient outcomes. CDK2/4/6, cyclin D1/E1 and RB1 mRNA expression were evaluated in the publicly available ovarian TCGA dataset. We observed nuclear and cytoplasmic staining for CDK2/4/6, cyclins D1/E1 and RB1/pRB1 in OCs with varying percentages. Increased nuclear CDK2 and nuclear cyclin E1 expression was linked with poor progression-free survival (PFS) and a shorter overall survival (OS). Nuclear CDK6 was associated with poor OS. The cytoplasmic expression of CDK4, cyclin D1 and cyclin E1 also has predictive and/or prognostic significance in OCs. In the multivariate analysis, nuclear cyclin E1 was an independent predictor of poor PFS. Tumours with high nuclear cyclin E1/high nuclear CDK2 have a worse PFS and OS. Detailed bioinformatics in the TCGA cohort showed a positive correlation between cyclin E1 and CDK2. We also showed that cyclin-E1-overexpressing tumours are enriched for genes involved in insulin signalling and release. Our data not only identified the prognostic/predictive significance of these key cell cycle regulators but also demonstrate the importance of sub-cellular localisation. CDK2 targeting in cyclin-E1-amplified OCs could be a rational approach.

Immune infiltration, aggressive pathology, and poor survival outcomes in RECQL helicase deficient breast cancers

RECQL is essential for genomic stability. Here, we evaluated RECQL in 449 pure ductal carcinomas in situ (DCIS), 152 DCIS components of mixed DCIS/invasive breast cancer (IBC) tumors, 157 IBC components of mixed DCIS/IBC and 50 normal epithelial terminal ductal lobular units (TDLUs). In 726 IBCs, CD8+, FOXP3+, IL17+, PDL1+, PD1+ T-cell infiltration (TILs) were investigated in RECQL deficient and proficient cancers. Tumor mutation burden (TMB) was evaluated in five RECQL germ-line mutation carriers with IBC by genome sequencing. Compared with normal epithelial cells, a striking reduction in nuclear RECQL in DCIS was evident with aggressive pathology and poor survival. In RECQL deficient IBCs, CD8+, FOXP3+, IL17+ or PDL1+ TILs were linked with aggressive pathology and shorter survival. In germline RECQL mutation carriers, increased TMB was observed in 4/5 tumors. We conclude that RECQL loss is an early event in breast cancer and promote immune cell infiltration.

Altered Regulation of the Glucose Transporter GLUT3 in PRDX1 Null Cells Caused Hypersensitivity to Arsenite

Targeting tumour metabolism through glucose transporters is an attractive approach. However, the role these transporters play through interaction with other signalling proteins is not yet defined. The glucose transporter SLC2A3 (GLUT3) is a member of the solute carrier transporter proteins. GLUT3 has a high affinity for D-glucose and regulates glucose uptake in the neurons, as well as other tissues. Herein, we show that GLUT3 is involved in the uptake of arsenite, and its level is regulated by peroxiredoxin 1 (PRDX1). In the absence of PRDX1, GLUT3 mRNA and protein expression levels are low, but they are increased upon arsenite treatment, correlating with an increased uptake of glucose. The downregulation of GLUT3 by siRNA or deletion of the gene by CRISPR cas-9 confers resistance to arsenite. Additionally, the overexpression of GLUT3 sensitises the cells to arsenite. We further show that GLUT3 interacts with PRDX1, and it forms nuclear foci, which are redistributed upon arsenite exposure, as revealed by immunofluorescence analysis. We propose that GLUT3 plays a role in mediating the uptake of arsenite into cells, and its homeostatic and redox states are tightly regulated by PRDX1. As such, GLUT3 and PRDX1 are likely to be novel targets for arsenite-based cancer therapy.

Clinical Impact of CDK4/6 Inhibitors in De Novo or PR- or Very Elderly Post-Menopausal ER+/HER2- Advanced Breast Cancers

The CDK4/6 inhibitors significantly increase progression-free survival (PFS) in ER+/HER2- advanced breast cancer patients. In clinical trials, overall survival (OS) improvement has been demonstrated for ribociclib and abemaciclib but not for palbociclib. We undertook a real-world evaluation of PFS and OS in 227 post-menopausal patients who received first-line CDK4/6 inhibitors. There is no significant difference in median PFS (27.5 months vs. 25.7 months, p = 0.3) or median OS (49.5 months vs. 50.2 months, p = 0.67) in patients who received either palbociclib or ribociclib, respectively. De novo disease is significantly associated with prolonged median PFS and median OS compared with recurrence disease (47.1 months vs. 20.3 months (p = 0.0002) and 77.4 months vs. 37.3 months (p = 0.0003), respectively). PR- tumours have significantly reduced median PFS and OS compared with PR+ disease (19.2 months vs. 38 months (p = 0.003) and 34.3 months vs. 62.6 months (p = 0.02), respectively). In the very elderly (>80 years), median PFS and OS are significantly shorter compared with patients who are 65 years or below (14.5 months vs. 30.2 months (p = 0.01), and 77.4 months vs. 29.6 months (p = 0.009), respectively) in the palbociclib group. Our data suggest that the benefit in the very elderly is limited, and PR+/de novo disease obtains the maximum survival benefit.

Characteristics and prognostic significance of polo-like kinase-1 (PLK1) expression in breast cancer

AIM

Polo-like kinase-1 (PLK1) plays a crucial role in cell cycle progression, and it is considered a potential therapeutic target in many cancers. Although the role of PLK1 is well established in triple-negative breast cancer (TNBC) as an oncogene, its role in luminal BC is still controversial. In this study, we aimed to evaluate the prognostic and predictive role of PLK1 in BC and its molecular subtypes.

METHODS

A large BC cohort (n = 1208) were immunohistochemically stained for PLK1. The association with clinicopathological, molecular subtypes, and survival data was analysed. PLK1 mRNA was evaluated in the publicly available datasets (n = 6774), including The Cancer Genome Atlas and the Kaplan-Meier Plotter tool.

RESULTS

20% of the study cohort showed high cytoplasmic PLK1 expression. High PLK1 expression was significantly associated with a better outcome in the whole cohort, luminal BC. In contrast, high PLK1 expression was associated with a poor outcome in TNBC. Multivariate analyses indicated that high PLK1 expression is independently associated with longer survival in luminal BC, and in poorer prognosis in TNBC. At the mRNA levels, PLK1 expression was associated with short survival in TNBC consistent with the protein expression. However, in luminal BC, its prognostic value significantly varies between cohorts.

CONCLUSION

The prognostic role of PLK1 in BC is molecular subtype-dependent. As PLK1 inhibitors are introduced to clinical trials for several cancer types, our study supports evaluation of the pharmacological inhibition of PLK1 as an attractive therapeutic target in TNBC. However, in luminal BC, PLK1 prognostic role remains controversial.

Selective Killing of BRCA2-Deficient Ovarian Cancer Cells via MRE11 Blockade

The MRE11 nuclease is essential during DNA damage recognition, homologous recombination, and replication. BRCA2 plays important roles during homologous recombination and replication. Here, we show that effecting an MRE11 blockade using a prototypical inhibitor (Mirin) induces synthetic lethality (SL) in BRCA2-deficient ovarian cancer cells, HeLa cells, and 3D spheroids compared to BRCA2-proficient controls. Increased cytotoxicity was associated with double-strand break accumulation, S-phase cell cycle arrest, and increased apoptosis. An in silico analysis revealed Mirin docking onto the active site of MRE11. While Mirin sensitises DT40 MRE11^+/- cells to the Top1 poison SN-38, it does not sensitise nuclease-dead MRE11 cells to this compound confirming that Mirin specifically inhibits Mre11 nuclease activity. MRE11 knockdown reduced cell viability in BRCA2-deficient PEO1 cells but not in BRCA2-proficient PEO4 cells. In a Mirin-resistant model, we show the downregulation of 53BP1 and DNA repair upregulation, leading to resistance, including in in vivo xenograft models. In a clinical cohort of human ovarian tumours, low levels of BRCA2 expression with high levels of MRE11 co-expression were linked with worse progression-free survival (PFS) (p = 0.005) and overall survival (OS) (p = 0.001). We conclude that MRE11 is an attractive SL target, and the pharmaceutical development of MRE11 inhibitors for precision oncology therapeutics may be of clinical benefit.

Targeting DNA damage repair precision medicine strategies in cancer

DNA repair targeted therapeutics is a promising precision medicine strategy in cancer. The development and clinical use of PARP inhibitors has transformed lives for many patients with BRCA germline deficient breast and ovarian cancer as well as platinum sensitive epithelial ovarian cancers. However, lessons learnt from the clinical use of PARP inhibitors also confirm that not all patients respond either due to intrinsic or acquired resistance. Therefore, the search for additional synthetic lethality approaches is an active area of translational and clinical research. Here, we review the current clinical state of PARP inhibitors and other evolving DNA repair targets including ATM, ATR, WEE1 inhibitors and others in cancer.

The Current Status of DNA-Repair-Directed Precision Oncology Strategies in Epithelial Ovarian Cancers

Survival outcomes for patients with advanced ovarian cancer remain poor despite advances in chemotherapy and surgery. Platinum-based systemic chemotherapy can result in a response rate of up to 80%, but most patients will have recurrence and die from the disease. Recently, the DNA-repair-directed precision oncology strategy has generated hope for patients. The clinical use of poly(ADP-ribose) polymerase (PARP) inhibitors in BRCA germ-line-deficient and/or platinum-sensitive epithelial ovarian cancers has improved survival. However, the emergence of resistance is an ongoing clinical challenge. Here, we review the current clinical state of PARP inhibitors and other clinically viable targeted approaches in epithelial ovarian cancers.

Evaluation oncotype DX® 21-gene recurrence score and clinicopathological parameters: a single institutional experience

AIMS

Oncotype DX recurrence score (RS) is a clinically validated assay, which predicts the likelihood of disease recurrence in oestrogen receptor-positive/HER2-negative (ER+/HER2-) breast cancer (BC). In this study we aimed to compare the performance of Oncotype DX against the conventional clinicopathological parameters using a large BC cohort diagnosed in a single institution.

METHODS AND RESULTS

A cohort (n = 430) of ER+/HER2- BC patients who were diagnosed at the Nottingham University Hospitals NHS Trust and had Oncotype DX testing was included. Correlation with the clinicopathological and other biomarkers, including the proliferation index, was analysed. The median Oncotype DX RS was 17.5 (range = 0-69). There was a significant association between high RS and grade 3 tumours. No grade 1 BC or grade 2 tumours with mitosis score 1 showed high RS. Low RS was significantly associated with special tumour types where none of the patients with classical lobular or tubular carcinomas had a high RS. There was an inverse association between RS and levels of ER and progesterone receptor (PR) expression and a positive linear correlation with Ki67 labelling index. Notably, six patients who developed recurrence had an intermediate RS; however, four of these six cases (67%) were identified as high-risk disease when the conventional clinical and molecular parameters were considered.

CONCLUSION

Oncotype DX RS is correlated strongly with the conventional clinicopathological parameters in BC. Some tumour features such as tumour grade, type, PR status and Ki67 index can be used as surrogate markers in certain scenarios.

Unravelling the clinicopathological and functional significance of replication protein A (RPA) heterotrimeric complex in breast cancers

Replication Protein A (RPA), a heterotrimeric complex consisting of RPA1, 2, and 3 subunits, is a single-stranded DNA (ssDNA)-binding protein that is critically involved in replication, checkpoint regulation and DNA repair. Here we have evaluated RPA in 776 pure ductal carcinomas in situ (DCIS), 239 DCIS that co-exist with invasive breast cancer (IBC), 50 normal breast tissue and 4221 IBC. Transcriptomic [METABRIC cohort (n = 1980)] and genomic [TCGA cohort (n = 1090)] evaluations were completed. Preclinically, RPA deficient cells were tested for cisplatin sensitivity and Olaparib induced synthetic lethality. Low RPA linked to aggressive DCIS, aggressive IBC, and shorter survival outcomes. At the transcriptomic level, low RPA tumours overexpress pseudogene/lncRNA as well as genes involved in chemical carcinogenesis, and drug metabolism. Low RPA remains linked with poor outcome. RPA deficient cells are sensitive to cisplatin and Olaparib induced synthetic lethality. We conclude that RPA directed precision oncology strategy is feasible in breast cancers.

Abstract P3-05-18: Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers

Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers Mashael Algethami1, Michael S Toss 1,4, Juliette Brownlie 1, Corinne L Woodcock 1,2, Chandar Jaipal1, Ahmed Shoqafi 1, Katia A Mesquita1, Adel Alblihy1,3, Andrew R Green1, Nigel P Mongan 1,5, Emad A Rakha 1,4, Jennie N Jeyapalan 1,2 and Srinivasan Madhusudan1,6 1 Nottingham Biodiscovery Institute, Academic Unit for Translational Medical Sciences, School of Medicine, University of Nottingham, University Park, Nottingham NG7 2RD, UK. 2 Faculty of Medicine and Health Sciences, Centre for Cancer Sciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, UK 3 Medical Center, King Fahad Security College (KFSC), Riyadh 11461, Saudi Arabia. 4 Department of Pathology, Nottingham University Hospital, City Campus, Hucknall Road, Nottingham NG5 1PB, UK. 5 Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA 6 Department of Oncology, Nottingham University Hospitals, Nottingham NG5 1PB, UK.   Introduction: Replication Protein A (RPA) is a critical single-stranded DNA (ssDNA)-binding protein that coats and protects exposed ssDNA from endogenous nucleases. RPA is a heterotrimeric complex consisting of RPA1 (70kDa), RPA2 (32kDa), and RPA3 (14kDa) subunits. RPA provides a platform for recruitment of factors required during replication, checkpoint regulation, DNA repair [including homologous recombination (HR), nucleotide excision repair (NER), base excision repair (BER) and mismatch repair (MMR)], telomere maintenance and retro-transposition. To understand the role of RPA in breast cancer pathogenesis we conducted a comprehensive genomic, transcriptomic, bioinformatic, proteomic and preclinical study. Patients and methods: RPA1, RPA2 and RPA3 protein expression was evaluated in 4221 primary invasive breast carcinomas and 776 breast ductal carcinoma in situ (DCIS). Transcriptomic investigation was completed in the METABRIC cohort (n=1980). Detailed bioinformatics was conducted in the TCGA cohort (n=1090). RPA deficient breast cancer cell lines were tested for Cisplatin, Palbociclib and Olaparib sensitivity. Results: RPA1, RPA2 and RPA3 loss is frequent in DCIS and linked to aggressive phenotype (including high grade, ER and PR negativity) (all p values < 0.01). DCIS with low RPA1 was also associated with poor local recurrence-free interval (p< 0.00001). In invasive breast cancers, low RPA1, low RPA2 and low RPA3 were all associated with larger size, lympho-vascular invasion, higher histological grade, high stage, ER negativity and poor breast cancer specific survival. Transcriptomic alterations in low RPA tumors included those genes involved in steroid hormone biosynthesis, chemical carcinogenesis, and drug metabolism. Pre-clinically, RPA deficient breast cancer cells were sensitive to Cisplatin and Palbociclib (CDK4/6 inhibitor) therapy compared to controls. Additionally, the PARP1 inhibitor Olaparib was synthetically lethal in RPA1 and RPA2 deficient cells compared to controls. Increased Olaparib sensitivity was associated with double strand breaks, S-phase cell cycle arrest and increased apoptosis. Conclusions: We provide the first comprehensive evidence that RPA loss is an early event during breast cancer pathogenesis and promotes aggressive phenotypes. Pre-clinically RPA deficient breast cancer cells were selectively toxic to Cisplatin, Palbociclib and Olaparib.

Citation Format: Mashael A. Algethami, Michael Toss, Juliette Brownlie, Corinne L. Woodcock, Chandar Jaipal, AHMED SHOQAFI, Katia Mesquita, Adel Alblihy, Nigel Mongan, Emad Rakha, Jennie N. Jeyapalan, Srinivasan Madhusudan, Andrew R. Green. Unravelling the clinicopathological and functional significance of Replication Protein A (RPA) heterotrimeric complex in sporadic breast cancers [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-18.

Abstract GS2-02: GS2-02 Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: Updated survival results of the randomized, phase 3 study DESTINY-Breast03

Background: Trastuzumab deruxtecan (T-DXd) is approved in the United States and European Union for use in patients (pts) with HER2+ unresectable/metastatic breast cancer (mBC) after ≥1 prior anti–HER2 regimen(s). Approval was based on the randomized, multicenter, open-label, phase 3 DESTINY-Breast03 study (NCT03529110), in which T-DXd demonstrated statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared with trastuzumab emtansine (T-DM1). At the primary interim analysis (data cutoff May 21, 2021), the risk of disease progression or death was reduced by 72% with T-DXd (P < 0.001; Cortes et al. N Engl J Med 2022). Overall survival (OS) data were immature for both treatment groups; although the prespecified cutoff for significance was not reached (NR), a trend toward benefit with T-DXd was observed. With further follow-up, we report results from the prespecified OS analysis of DESTINY-Breast03 (data cutoff July 25, 2022), including updated efficacy and safety.

Methods: Pts with HER2+ mBC previously treated with trastuzumab and a taxane in either the metastatic setting or (neo)adjuvant setting with progression within 6 mo of therapy, who could have received pertuzumab, were randomly assigned 1:1 to receive T-DXd 5.4 mg/kg every 3 weeks (Q3W) or T-DM1 3.6 mg/kg Q3W until disease progression. The primary endpoint was PFS by blinded independent central review (BICR). The key secondary endpoint was OS (80% powered at 2-sided significance level of 5%); other secondary endpoints included objective response rate (ORR), duration of response (DoR), PFS based on investigator assessment, and safety.

Results: 524 pts received either T-DXd (n = 261) or T-DM1 (n = 263). As of the updated data cutoff, median duration of study follow-up was 28.4 mo (range, 0.0-46.9 mo) for T-DXd and 26.5 mo (range, 0.0-45.0 mo) for T-DM1. Median treatment duration was 18.2 mo (range, 0.7-44.0 mo) for T DXd and 6.9 mo (range, 0.7-39.3 mo) for T-DM1. The risk of death was reduced by 36% (HR, 0.64; P = 0.0037) with T-DXd; median OS (mOS) was NR (95% CI, 40.5 mo-not evaluable [NE]), with 72 (27.6%) OS events, for T-DXd vs NR (95% CI, 34.0 mo-NE), with 97 (36.9%) OS events, for T-DM1. Landmark 12-mo OS rate was 94.1% (95% CI, 90.4-96.4) for T-DXd vs 86.0% (95% CI, 81.1-89.8) for T-DM1; 24-mo OS rate was 77.4% (95% CI, 71.7-82.1) for T-DXd vs 69.9% (95% CI, 63.7-75.2) for T-DM1. The P value for OS crossed the prespecified boundary (P = 0.013) and was statistically significant. mPFS by BICR was 28.8 mo (95% CI, 22.4-37.9 mo) with T-DXd, compared with 6.8 mo (95% CI, 5.6-8.2 mo) with T-DM1; HR, 0.33; nominal P < 0.000001. Key efficacy and safety results are shown in the table. Grade ≥3 treatment-emergent adverse events were experienced by 56.4% of T-DXd-treated pts and 51.7% of T DM1-treated pts. Drug-related interstitial lung disease/pneumonitis, as evaluated by an independent adjudication committee, was experienced by 39 pts (15.2%) in the T-DXd arm and 8 pts (3.1%) in the T DM1 arm; no adjudicated drug-related grade 4 or 5 events were observed in pts who received T-DXd.

Conclusions: Updated results confirm the superiority of T-DXd compared with T-DM1 for pts with HER2+ mBC previously treated with an anti-HER2 therapy, with highly clinically meaningful and statistically significant benefit in OS and PFS and a manageable safety profile with longer treatment duration.

Editorial Acknowledgment

Under the guidance of authors, assistance in medical writing and editorial support was provided by Laura Halvorson, PhD, and Rachel Hood, PhD, of ApotheCom, and was funded by Daiichi Sankyo.

Funding

This study was funded by Daiichi Sankyo and AstraZeneca.

Table. Summary of Efficacy Results for T-DXd and T-DM1

Citation Format: Sara Hurvitz, Roberto Hegg, Wei-Pang Chung, Seock-Ah Im, William Jacot, Vinod Ganju, Joanne Win Yang Chiu, Binghe Xu, Erika Hamilton, Srinivasan Madhusudan, Hiroji Iwata, Sevilay Altintas, Jan-Willem Henning, Giuseppe Curigliano, José Manuel Pérez-García, Anton Egorov, Yali Liu, Jillian Cathcart, Shahid Ashfaque, Javier Cortés. GS2-02 Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: Updated survival results of the randomized, phase 3 study DESTINY-Breast03 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS2-02.

Trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer: updated results from DESTINY-Breast03, a randomised, open-label, phase 3 trial

BACKGROUND

An improvement in progression-free survival was shown with trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer in the progression-free survival interim analysis of the DESTINY-Breast03 trial. The aim of DESTINY-Breast03 was to compare the efficacy and safety of trastuzumab deruxtecan versus trastuzumab emtansine.

METHODS

This open-label, randomised, multicentre, phase 3 trial was done in 169 study centres in North America, Asia, Europe, Australia, and South America. Eligible patients were aged 18 or older, had HER2-positive unresectable or metastatic breast cancer previously treated with trastuzumab and a taxane, had an Eastern Cooperative Oncology Group performance status 0-1, and at least one measurable lesion per Response Evaluation Criteria in Solid Tumours version 1.1. Patients were randomly assigned (1:1) to receive trastuzumab deruxtecan 5·4 mg/kg or trastuzumab emtansine 3·6 mg/kg, both administered by intravenous infusion every 3 weeks. Randomisation was stratified by hormone receptor status, previous treatment with pertuzumab, and history of visceral disease, and was managed through an interactive web-based system. Within each stratum, balanced block randomisation was used with a block size of four. Patients and investigators were not masked to the treatment received. The primary endpoint was progression-free survival by blinded independent central review. The key secondary endpoint was overall survival and this prespecified second overall survival interim analysis reports updated overall survival, efficacy, and safety results. Efficacy analyses were performed using the full analysis set. Safety analyses included all randomly assigned patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03529110.

FINDINGS

Between July 20, 2018, and June 23, 2020, 699 patients were screened for eligibility, 524 of whom were enrolled and randomly assigned to receive trastuzumab deruxtecan (n=261) or trastuzumab emtansine (n=263). Median duration of study follow-up was 28·4 months (IQR 22·1-32·9) with trastuzumab deruxtecan and 26·5 months (14·5-31·3) with trastuzumab emtansine. Median progression-free survival by blinded independent central review was 28·8 months (95% CI 22·4-37·9) with trastuzumab deruxtecan and 6·8 months (5·6-8·2) with trastuzumab emtansine (hazard ratio [HR] 0·33 [95% CI 0·26-0·43]; nominal p<0·0001). Median overall survival was not reached (95% CI 40·5 months-not estimable), with 72 (28%) overall survival events, in the trastuzumab deruxtecan group and was not reached (34·0 months-not estimable), with 97 (37%) overall survival events, in the trastuzumab emtansine group (HR 0·64; 95% CI 0·47-0·87]; p=0·0037). The number of grade 3 or worse treatment-emergent adverse events was similar in patients who received trastuzumab deruxtecan versus trastuzumab emtansine (145 [56%] patients versus 135 [52%] patients). Adjudicated drug-related interstitial lung disease or pneumonitis occurred in 39 (15%) patients treated with trastuzumab deruxtecan and eight (3%) patients treated with trastuzumab emtansine, with no grade 4 or 5 events in either group.

INTERPRETATION

Trastuzumab deruxtecan showed a significant improvement in overall survival versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer, as well as the longest reported median progression-free survival, reaffirming trastuzumab deruxtecan as the standard of care in the second-line setting. A manageable safety profile of trastuzumab deruxtecan was confirmed with longer treatment duration.

FUNDING

Daiichi Sankyo and AstraZeneca.

Clinical and molecular significance of the RNA m6A methyltransferase complex in prostate cancer

N⁶-methyladenosine (m⁶A) is the most abundant internal mRNA modification and is dynamically regulated through distinct protein complexes that methylate, demethylate, and/or interpret the m⁶A modification. These proteins, and the m⁶A modification, are involved in the regulation of gene expression, RNA stability, splicing and translation. Given its role in these crucial processes, m⁶A has been implicated in many diseases, including in cancer development and progression. Prostate cancer (PCa) is the most commonly diagnosed non-cutaneous cancer in men and recent studies support a role for m⁶A in PCa. Despite this, the literature currently lacks an integrated analysis of the expression of key components of the m⁶A RNA methyltransferase complex, both in PCa patients and in well-established cell line models. For this reason, this study used immunohistochemistry and functional studies to investigate the mechanistic and clinical significance of the METTL3, METTL14, WTAP and CBLL1 components of the m⁶A methyltransferase complex in PCa specimens and cell lines. Expression of METTL3 and CBLL1, but not METTL14 and WTAP, was associated with poorer PCa patient outcomes. Expression of METTL3, METTL14, WTAP and CBLL1 was higher in PCa cells compared with non-malignant prostate cells, with the highest expression seen in castrate-sensitive, androgen-responsive PCa cells. Moreover, in PCa cell lines, expression of METTL3 and WTAP was found to be androgen-regulated. To investigate the mechanistic role(s) of the m⁶A methyltransferase complex in PCa cells, short hairpin RNA (shRNA)-mediated knockdown coupled with next generation sequencing was used to determine the transcriptome-wide roles of METTL3, the catalytic subunit of the m⁶A methyltransferase complex. Functional depletion of METTL3 resulted in upregulation of the androgen receptor (AR), together with 134 AR-regulated genes. METTL3 knockdown also resulted in altered splicing, and enrichment of cell cycle, DNA repair and metabolic pathways. Collectively, this study identified the functional and clinical significance of four essential m⁶A complex components in PCa patient specimens and cell lines for the first time. Further studies are now warranted to determine the potential therapeutic relevance of METTL3 inhibitors in development to treat leukaemia to benefit patients with PCa.

The KDM5B and KDM1A lysine demethylases cooperate in regulating androgen receptor expression and signalling in prostate cancer

Histone H3 lysine 4 (H3K4) methylation is key epigenetic mark associated with active transcription and is a substrate for the KDM1A/LSD1 and KDM5B/JARID1B lysine demethylases. Increased expression of KDM1A and KDM5B is implicated in many cancer types, including prostate cancer (PCa). Both KDM1A and KDM5B interact with AR and promote androgen regulated gene expression. For this reason, there is great interested in the development of new therapies targeting KDM1A and KDM5B, particularly in the context of castrate resistant PCa (CRPC), where conventional androgen deprivation therapies and androgen receptor signalling inhibitors are no longer effective. As there is no curative therapy for CRPC, new approaches are urgently required to suppress androgen signalling that prevent, delay or reverse progression to the castrate resistant state. While the contribution of KDM1A to PCa is well established, the exact contribution of KDM5B to PCa is less well understood. However, there is evidence that KDM5B is implicated in numerous pro-oncogenic mechanisms in many different types of cancer, including the hypoxic response, immune evasion and PI3/AKT signalling. Here we elucidate the individual and cooperative functions of KDM1A and KDM5B in PCa. We show that KDM5B mRNA and protein expression is elevated in localised and advanced PCa. We show that the KDM5 inhibitor, CPI-455, impairs androgen regulated transcription and alternative splicing. Consistent with the established role of KDM1A and KDM5B as AR coregulators, we found that individual pharmacologic inhibition of KDM1A and KDM5 by namoline and CPI-455 respectively, impairs androgen regulated transcription. Notably, combined inhibition of KDM1A and KDM5 downregulates AR expression in CRPC cells. Furthermore, combined KDM1A and KDM5 inhibition impairs PCa cell proliferation and invasion more than individual inhibition of KDM1A and KDM5B. Collectively our study has identified individual and cooperative mechanisms involving KDM1A and KDM5 in androgen signalling in PCa. Our findings support the further development of KDM1A and KDM5B inhibitors to treat advanced PCa. Further work is now required to confirm the therapeutic feasibility of combined inhibition of KDM1A and KDM5B as a novel therapeutic strategy for targeting AR positive CRPC.

Towards Personalized Management of Ovarian Cancer

Despite advances in surgery and chemotherapy, the overall outcomes for patients with advanced ovarian cancer remain poor. Although initial response rates to platinum-based chemotherapy is about 60-80%, most patients will have recurrence and succumb to the disease. However, a DNA repair-directed precision medicine strategy has recently generated real hope in improving survival. The clinical development of PARP inhibitors has transformed lives for many patients with BRCA germline-deficient and/or platinum-sensitive epithelial ovarian cancers. Antiangiogenic agents and intraperitoneal chemotherapy approaches may also improve outcomes in patients. Moreover, evolving immunotherapeutic opportunities could also positively impact patient outcomes. Here we review the current clinical state of PARP inhibitors and other clinically viable targeted approaches in ovarian cancer.

The METTL3 RNA Methyltransferase Regulates Transcriptional Networks in Prostate Cancer

Simple Summary

Prostate cancer is driven by androgen receptor-regulated transcription and is a leading cause of cancer deaths. For this reason, androgen deprivation therapies are commonly used to treat advanced prostate cancer. These treatments are often effective for short durations before the emergence of treatment resistance and disease progression to castrate resistant prostate cancer or neuroendocrine-like disease. The aim of this study was to address whether new therapies targeting the epitranscriptome may suppress androgen signalling and thus represent a novel approach to prostate cancer treatment.

Abstract

Prostate cancer (PCa) is a leading cause of cancer-related deaths and is driven by aberrant androgen receptor (AR) signalling. For this reason, androgen deprivation therapies (ADTs) that suppress androgen-induced PCa progression either by preventing androgen biosynthesis or via AR signalling inhibition (ARSi) are common treatments. The N6-methyladenosine (m6A) RNA modification is involved in regulating mRNA expression, translation, and alternative splicing, and through these mechanisms has been implicated in cancer development and progression. RNA-m6A is dynamically regulated by the METTL3 RNA methyltransferase complex and the FTO and ALKBH5 demethylases. While there is evidence supporting a role for aberrant METTL3 in many cancer types, including localised PCa, the wider contribution of METTL3, and by inference m6A, in androgen signalling in PCa remains poorly understood. Therefore, the aim of this study was to investigate the expression of METTL3 in PCa patients and study the clinical and functional relevance of METTL3 in PCa. It was found that METTL3 is aberrantly expressed in PCa patient samples and that siRNA-mediated METTL3 knockdown or METTL3-pharmacological inhibition significantly alters the basal and androgen-regulated transcriptome in PCa, which supports targeting m6A as a novel approach to modulate androgen signalling in PCa.

O085 CD10 expression in carcinomas of the pancreas, bile duct and ampulla

Introduction

Pancreatic cancer and cholangiocarcinoma including, cancer of ampulla of Vater, are very aggressive and have a dismal prognosis; hence improved methods of patient stratification are required.

Methods

We assessed the expression of CD10 in stromal and epithelial cells of two patient cohorts using immunohistochemistry on tissue microarrays. The first cohort was composed of 68 pancreatic adenocarcinomas and the second cohort was composed of 120 cancers of the bile duct and ampulla.

Results

In bile duct and ampullary carcinomas an association was observed between CD10 stromal expression and patient age (p =0.009). The CD10 stromal expression was associated with poor disease specific survival (DSS) (p =0.05). In multivariate Cox model for DSS, stromal CD10 expression (p = 0.037) was independently associated with poor outcome. In multivariate Cox model for disease free survival (DFS), CD10 stromal expression (p = 0.012), and nodal status (p = 0.025) were independently associated with poor outcome. In pancreatic cancer, no statistically significant association was observed between CD 10 stromal expression and clinicopathological variables such as tumour size (p = 0.099), T stage (p = 0.393), N stage (p = 0.860), Vascular invasion (p = 0.904), perineural invasion (p = 0.532) and grade (0.168). In multivariate Cox model for DSS, T stage (p = 0.042) was independently associated with poor outcome.

Conclusion

The results suggest that CD10 stromal expression may have prognostic significance in cholangiocarcinoma. The findings of this study warrant a larger follow-up study.

Take-home message

The results suggest that CD10 stromal expression may have prognostic significance in cholangiocarcinoma. The findings of this study warrant a larger follow-up study.

Targeting Mre11 overcomes platinum resistance and induces synthetic lethality in XRCC1 deficient epithelial ovarian cancers

Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n = 331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p = 0.002). In the ovarian cancer genome atlas (TCGA) cohort (n = 498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p < 0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n = 1259), Mre11 overexpression was associated with poor PFS (p = 0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.

Can Cisplatin Therapy Be Improved? Pathways That Can Be Targeted

Cisplatin (cis-diamminedichloroplatinum (II)) is the oldest known chemotherapeutic agent. Since the identification of its anti-tumour activity, it earned a remarkable place as a treatment of choice for several cancer types. It remains effective against testicular, bladder, lung, head and neck, ovarian, and other cancers. Cisplatin treatment triggers different cellular responses. However, it exerts its cytotoxic effects by generating inter-strand and intra-strand crosslinks in DNA. Tumour cells often develop tolerance mechanisms by effectively repairing cisplatin-induced DNA lesions or tolerate the damage by adopting translesion DNA synthesis. Cisplatin-associated nephrotoxicity is also a huge challenge for effective therapy. Several preclinical and clinical studies attempted to understand the major limitations associated with cisplatin therapy, and so far, there is no definitive solution. As such, a more comprehensive molecular and genetic profiling of patients is needed to identify those individuals that can benefit from platinum therapy. Additionally, the treatment regimen can be improved by combining cisplatin with certain molecular targeted therapies to achieve a balance between tumour toxicity and tolerance mechanisms. In this review, we discuss the importance of various biological processes that contribute to the resistance of cisplatin and its derivatives. We aim to highlight the processes that can be modulated to suppress cisplatin resistance and provide an insight into the role of uptake transporters in enhancing drug efficacy.

High Expression of RECQL Protein in ER-Positive Breast Tumours Is Associated With a Better Survival

Background

RECQL (also known as RECQ1 and RECQL1) is a gene of recent interest in breast cancer and an association between high levels of RECQL protein in breast cancer tumour cells and good survival of patients has been reported.

Methods

To validate this association, we measured the RECQL protein levels in tumours of 933 breast cancer patients using immunohistochemistry analysis and followed the patients for death from breast cancer.

Results

Women with a level of RECQL protein above the 75th percentile had better 15-year disease-specific survival among ER-positive patients (62.5% vs. 48.7%, HR= 0.72, 95%CI= 0.52-0.98, p-value = 0.04), but not among ER- patients (48.9% vs. 48.0%, HR= 1.07, 95%CI= 0.67-1.69, p-value= 0.79). Among the ER-negative patients, high RECQL protein levels were associated with better survival among women who received tamoxifen treatment (67.0% vs. 51.5%, HR= 0.64, 95%CI= 0.41-0.99, p-value= 0.04).

Conclusion

RECQL might be a new predictive marker for tamoxifen treatment among ER-positive patients.

Exploring anti-androgen therapies in hormone dependent prostate cancer and new therapeutic routes for castration resistant prostate cancer

Androgen deprivation therapies (ADTs) are important treatments which inhibit androgen-induced prostate cancer (PCa) progression by either preventing androgen biosynthesis (e.g. abiraterone) or by antagonizing androgen receptor (AR) function (e.g. bicalutamide, enzalutamide, darolutamide). A major limitation of current ADTs is they often remain effective for limited durations after which patients commonly progress to a lethal and incurable form of PCa, called castration-resistant prostate cancer (CRPC) where the AR continues to orchestrate pro-oncogenic signalling. Indeed, the increasing numbers of ADT-related treatment-emergent neuroendocrine-like prostate cancers (NePC), which lack AR and are thus insensitive to ADT, represents a major therapeutic challenge. There is therefore an urgent need to better understand the mechanisms of AR action in hormone dependent disease and the progression to CRPC, to enable the development of new approaches to prevent, reverse or delay ADT-resistance. Interestingly the AR regulates distinct transcriptional networks in hormone dependent and CRPC, and this appears to be related to the aberrant function of key AR-epigenetic coregulator enzymes including the lysine demethylase 1 (LSD1/KDM1A). In this review we summarize the current best status of anti-androgen clinical trials, the potential for novel combination therapies and we explore recent advances in the development of novel epigenetic targeted therapies that may be relevant to prevent or reverse disease progression in patients with advanced CRPC.

Untangling the clinicopathological significance of MRE11-RAD50-NBS1 complex in sporadic breast cancers

The MRE11-RAD50-NBS1 (MRN) complex is critical for genomic stability. Although germline mutations in MRN may increase breast cancer susceptibility, such mutations are extremely rare. Here, we have conducted a comprehensive clinicopathological study of MRN in sporadic breast cancers. We have protein expression profiled for MRN and a panel of DNA repair factors involved in double-strand break repair (BRCA1, BRCA2, ATM, CHK2, ATR, Chk1, pChk1, RAD51, γH2AX, RPA1, RPA2, DNA-PKcs), RECQ DNA helicases (BLM, WRN, RECQ1, RECQL4, RECQ5), nucleotide excision repair (ERCC1) and base excision repair (SMUG1, APE1, FEN1, PARP1, XRCC1, Pol β) in 1650 clinical breast cancers. The prognostic significance of MRE11, RAD50 and NBS1 transcripts and their microRNA regulators (hsa-miR-494 and hsa-miR-99b) were evaluated in large clinical datasets. Expression of MRN components was analysed in The Cancer Genome Atlas breast cancer cohort. We show that low nuclear MRN is linked to aggressive histopathological phenotypes such as high tumour grade, high mitotic index, oestrogen receptor- and high-risk Nottingham Prognostic Index. In univariate analysis, low nuclear MRE11 and low nuclear RAD50 were associated with poor survival. In multivariate analysis, low nuclear RAD50 remained independently linked with adverse clinical outcomes. Low RAD50 transcripts were also linked with reduced survival. In contrast, overexpression of hsa-miR-494 and hsa-miR-99b microRNAs was associated with poor survival. We observed large-scale genome-wide alterations in MRN-deficient tumours contributing to aggressive behaviour. We conclude that MRN status may be a useful tool to stratify tumours for precision medicine strategies.

The frequency and clinical significance of DNA polymerase beta (POLβ) expression in breast ductal carcinoma in situ (DCIS)

Background

The prediction of clinical behaviour of breast ductal carcinoma in situ (DCIS) and its progression to invasive disease remains a challenge. Alterations of DNA damage repair mechanisms are associated with invasive breast cancer (BC). This study aims to assess the role of base excision repair (BER) DNA Polymerase Beta (POLβ) in DCIS.

Methods

A cohort of DCIS comprising pure DCIS (n = 776) and DCIS coexisting with invasive BC (n = 239) were prepared as tissue microarrays. POLβ protein expression was assessed using immunohistochemistry and correlated with clinicopathological parameters and patient outcome. Preclinically, we investigated the impact of POLβ depletion on stem cell markers in representative DCIS cell line models.

Results

Reduced POLβ expression was associated with aggressive DCIS features including high nuclear grade, comedo necrosis, larger tumour size, hormonal receptor negativity, HER2 overexpression and high Ki67 index. Combined low nuclear/low cytoplasmic POLβ expression showed the strongest association with the features’ characteristics of aggressive behaviour. There was a gradual reduction in the POLβ expression from normal breast tissue, to DCIS, with the lowest expression observed in the invasive BC. Low POLβ expression was an independent predictor of recurrence in DCIS patients treated with breast conserving surgery (BCS). POLβ knockdown was associated with a significant increase in cell stemness markers including SOX2, NANOG and OCT4 levels in MCF10-DCIS cell lines.

Conclusion

Loss of POLβ in DCIS is associated with aggressive behaviour and it can predict recurrence. POLβ expression in DCIS provides an additional feature for patients’ risk stratification for personalised therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06357-7.

Ligase 1 is a predictor of platinum resistance and its blockade is synthetically lethal in XRCC1 deficient epithelial ovarian cancers

Rationale: The human ligases (LIG1, LIG3 and LIG4) are essential for the maintenance of genomic integrity by catalysing the formation of phosphodiester bonds between adjacent 5′-phosphoryl and 3′-hydroxyl termini at single and double strand breaks in duplex DNA molecules generated either directly by DNA damage or during replication, recombination, and DNA repair. Whether LIG1, LIG3 and LIG4 can influence ovarian cancer pathogenesis and therapeutics is largely unknown.

Methods: We investigated LIG1, LIG3 and LIG4 expression in clinical cohorts of epithelial ovarian cancers [protein level (n=525) and transcriptional level (n=1075)] and correlated to clinicopathological features and survival outcomes. Pre-clinically, platinum sensitivity was investigated in LIG1 depleted ovarian cancer cells. A small molecule inhibitor of LIG1 (L82) was tested for synthetic lethality application in XRCC1, BRCA2 or ATM deficient cancer cells.

Results: LIG1 and LIG3 overexpression linked with aggressive phenotypes, platinum resistance and poor progression free survival (PFS). In contrast, LIG4 deficiency was associated with platinum resistance and worse PFS. In a multivariate analysis, LIG1 was independently associated with adverse outcome. In ovarian cancer cell lines, LIG1 depletion increased platinum cytotoxicity. L82 monotherapy was synthetically lethal in XRCC1 deficient ovarian cancer cells and 3D-spheroids. Increased cytotoxicity was linked with accumulation of DNA double strand breaks (DSBs), S-phase cell cycle arrest and increased apoptotic cells. L82 was also selectively toxic in BRCA2 deficient or ATM deficient cancer cells and 3D-spheroids.

Conclusions: We provide evidence that LIG1 is an attractive target for personalization of ovarian cancer therapy.

The prognostic significance of Flap Endonuclease 1 (FEN1) in breast ductal carcinoma in situ

Background

Impaired DNA repair mechanism is one of the cancer hallmarks. Flap Endonuclease 1 (FEN1) is essential for genomic integrity. FEN1 has key roles during base excision repair (BER) and replication. We hypothesised a role for FEN1 in breast cancer pathogenesis. This study aims to assess the role of FEN1 in breast ductal carcinoma in situ (DCIS).

Methods

Expression of FEN1 protein was evaluated in a large (n = 1015) well-characterised cohort of DCIS, comprising pure (n = 776) and mixed (DCIS coexists with invasive breast cancer (IBC); n = 239) using immunohistochemistry (IHC).

Results

FEN1 high expression in DCIS was associated with aggressive and high-risk features including higher nuclear grade, larger tumour size, comedo type necrosis, hormonal receptors negativity, higher proliferation index and triple-negative phenotype. DCIS coexisting with invasive BC showed higher FEN1 nuclear expression compared to normal breast tissue and pure DCIS but revealed significantly lower expression when compared to the invasive component. However, FEN1 protein expression in DCIS was not an independent predictor of local recurrence-free interval.

Conclusion

High FEN1 expression is linked to features of aggressive tumour behaviour and may play a role in the direct progression of DCIS to invasive disease. Further studies are warranted to evaluate its mechanistic roles in DCIS progression and prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06271-y.

Randomized multicenter trial of 3 weekly cabazitaxel versus weekly paclitaxel chemotherapy in the first-line treatment of HER2 negative metastatic breast cancer (MBC)

1008

Background: Paclitaxel is commonly used as first line chemotherapy for HER2 negative MBC. However, with response rates of 21.5-53.7% and a significant risk of peripheral neuropathy there is a need for more effective and better tolerated chemotherapy (CCT). Methods: This open label randomised (1:1) phase 2 trial compared 6 cycles of cabazitaxel (25 mg/m2) every 3 weeks, with weekly paclitaxel (80mg/m2) over 18 weeks as first line CCT. HER2 negative and performance status ≤1 patients were eligible. Patients on cabazitaxel received GCSF prophylaxis. Primary endpoint was Progression Free Survival (PFS) with 127 events required to detect a hazard ratio (HR) of 0.65 with 85% power. Secondary endpoints included objective response rate (ORR; RECIST 1.1), time to response (TTR), overall survival (OS), safety and tolerability and quality of life (QoL). Results: 158 patients were recruited from 14 UK hospitals (79 in each arm). Median age (range) was 56(34-81) in the cabazitaxel arm and 61(34-79) in the paclitaxel arm. 61% of patients were performance status 0. Median time on treatment was 15 weeks for both arms, but more patients on paclitaxel had a treatment delay (61% vs 39%) or dose reduction (37% vs 24%). Comparing cabazitaxel to paclitaxel after 146 PFS events, median PFS was 6.7 vs 5.8 months (HR 0.84; 95%CI 0.60–1.18, P = 0.3). There was no difference in OS, median 19.3 vs 20.0 months (HR 0.94; 95%CI 0.63-1.40, P = 0.7), ORR (42% vs 37%) or TTR (HR 1.09; 95%CI 0.68–1.74, P = 0.7). Grade ≥3 adverse events occurred in 42% of patients on cabazitaxel and 48% on paclitaxel. Diarrhoea, febrile neutropenia and nausea were the most common grade ≥3 events in the cabazitaxel arm with rates of 11%, 11% and 10% respectively compared to 1%, 1% and 0% in the paclitaxel arm. In the paclitaxel arm the top grade ≥3 events were lung infection and peripheral neuropathy, 6% and 5% respectively compared to 2.5% and 0% in the cabazitaxel arm. Peripheral neuropathy of any grade was reported by 55% of patients treated with paclitaxel vs 17% on cabazitaxel. Alopecia occurred in 41% of patients on paclitaxel compared to 27% on cabazitaxel. Adverse events leading to discontinuation were more frequent with paclitaxel (22%) than cabazitaxel (14%). Over the course of treatment, mean EQ5D single index utility score (+0.05; 95%CI 0.004-0.09, P = 0.03) and visual analogue scale score (+7.7; 95%CI 3.1-12.3, P = 0.001) were higher in the cabazitaxel arm compared to paclitaxel suggestive of better QoL on Cabazitaxel. Conclusions: 3 weekly cabazitaxel as first line chemotherapy in HER2 negative MBC does not significantly improve PFS compared to weekly paclitaxel, though it has a lower risk of peripheral neuropathy with better patient reported overall health outcomes. Cabazitaxel is safe and well tolerated for MBC and requires fewer hospital visits, an important consideration in the COVID pandemic and beyond. Clinical trial information: NCT03048942 .

Real-world outcomes from the systemic use of CDK 4/6 inhibitors (CDKIs) in the management of ER positive (+) HER2 negative (-) metastatic breast cancer (mBC)

e13031

Background: The use of CDKIs have transformed the management of ER+HER2- mBC. As the real-world data matures, this project describes patterns in response to systemic therapy that may inform treatment planning and prognostication. Methods: We analysed the ER+HER2- mBC dataset at Nottingham University Hospitals NHS Trust (NUH) generated by reviewing clinical notes, radiology and e-prescribing records to collect clinical data on patients treated with CDKIs between 01/10/2016 - 01/10/2020. Results: 272 patients with a median age of 65 years (30-90 years) were treated with CDKIs (palbociclib 54.0% (n=147); ribociclib 19.5% (n=53); abemaciclib 26.5% (n=72)) in combination with endocrine therapies (letrozole, anastrozole, exemestane and, fulvestrant). Median overall survival was 49.5 months. Treatment with first-line CDKIs (69.8%; n=190) resulted in superior PFS when compared to CDKIs in a ≥ second-line setting (30.2%; n=82) i.e., mPFS 21.3 vs 12.2 months (HR 0.67; 95% CI, 0.47-0.96; P=0.02). Univariate analysis shown in the table below indicates the benefit to PFS from presentations with de novo mBC and the absence of visceral metastases. In patients treated curatively for early breast cancer (EBC), better outcomes were demonstrated in patients presenting with mBC, >12 months versus ≤12 months of completion of adjuvant endocrine therapy i.e., mPFS 28.4 vs 12.1 months (HR 0.50; 95% CI, 0.30-0.84; P=0.004) when treated with first-line CDKIs. A multivariate analysis identified benefit to PFS from first-line therapy with CDKIs (HR 0.70; 95% CI, 0.49-1.01; P=0.05) and presentation with de novo mBC (HR 0.56; 95% CI, 0.37-0.85; P=0.006). The presence of visceral metastases was associated with poorer outcomes (HR 1.52; 95% CI, 1.08-2.15; P=0.01). Conclusions: This analysis confirms the PFS benefit from CDKIs demonstrated in clinical trials is mirrored in the real-world setting. The analysis was not powered to delineate survival benefit between the individual CDKIs. Presentations with mBC following a prior history of EBC, within ≤12 months of completion of adjuvant endocrine therapy, and with visceral metastases may help predict poorer clinical outcomes and may need to be considered when prognosticating and in treatment planning. This analysis is hypotheses-generating and we will confirm our findings in a prospective manner as the dataset is expanded.[Table: see text]

Clinicopathological and Functional Evaluation Reveal NBS1 as a Predictor of Platinum Resistance in Epithelial Ovarian Cancers

Platinum resistance seriously impacts on the survival outcomes of patients with ovarian cancers. Platinum-induced DNA damage is processed through DNA repair. NBS1 is a key DNA repair protein. Here, we evaluated the role of NBS1 in ovarian cancers. NBS1 expression was investigated in clinical cohorts (protein level (n = 331) and at the transcriptomic level (n = 1259)). Pre-clinically, sub-cellular localization of NBS1 at baseline and following cisplatin therapy was tested in platinum resistant (A2780cis, PEO4) and sensitive (A2780, PEO1) ovarian cancer cells. NBS1 was depleted and cisplatin sensitivity was investigated in A2780cis and PEO4 cells. Nuclear NBS1 overexpression was associated with platinum resistance (p = 0.0001). In univariate and multivariate analysis, nuclear NBS1 overexpression was associated with progression free survival (PFS) (p-values = 0.003 and 0.017, respectively) and overall survival (OS) (p-values = 0.035 and 0.009, respectively). NBS1 mRNA overexpression was linked with poor PFS (p = 0.011). Pre-clinically, following cisplatin treatment, we observed nuclear localization of NBS1 in A2780cis and PEO4 compared to A2780 and PEO1 cells. NBS1 depletion increased cisplatin cytotoxicity, which was associated with accumulation of double strand breaks (DSBs), S-phase cell cycle arrest, and increased apoptosis. NBS1 is a predictor of platinum sensitivity and could aid stratification of ovarian cancer therapy.

RAD50 deficiency is a predictor of platinum sensitivity in sporadic epithelial ovarian cancers

Intrinsic or acquired resistance seriously limits the use of platinating agents in advanced epithelial ovarian cancers. Increased DNA repair capacity is a key route to platinum resistance. RAD50 is a critical component of the MRN complex, a ‘first responder’ to DNA damage and essential for the repair of DSBs and stalled replication forks. We hypothesised a role for RAD50 in ovarian cancer pathogenesis and therapeutics. Clinicopathological significance of RAD50 expression was evaluated in clinical cohorts of ovarian cancer at the protein level (n = 331) and at the transcriptomic level (n = 1259). Sub-cellular localization of RAD50 at baseline and following cisplatin therapy was tested in platinum resistant (A2780cis, PEO4) and sensitive (A2780, PEO1) ovarian cancer cells. RAD50 was depleted and cisplatin sensitivity was investigated in A2780cis and PEO4 cells. RAD50 deficiency was associated with better progression free survival (PFS) at the protein (p = 0.006) and transcriptomic level (p < 0.001). Basal level of RAD50 was higher in platinum resistant cells. Following cisplatin treatment, increased nuclear localization of RAD50 was evident in A2780cis and PEO4 compared to A2780 and PEO1 cells. RAD50 depletion using siRNAs in A2780cis and PEO4 cells increased cisplatin cytotoxicity, which was associated with accumulation of DSBs, S-phase cell cycle arrest and increased apoptosis. We provide evidence that RAD50 deficiency is a predictor of platinum sensitivity. RAD50 expression-based stratification and personalization could be viable clinical strategy in ovarian cancers.

XRCC1 deficient triple negative breast cancers are sensitive to ATR, ATM and Wee1 inhibitor either alone or in combination with olaparib

Background:

PARP inhibitor (PARPi) monotherapy is a new strategy in BRCA germ-line deficient triple negative breast cancer (TNBC). However, not all patients respond, and the development of resistance limits the use of PARPi monotherapy. Therefore, the development of alternative synthetic lethality strategy, including in sporadic TNBC, is a priority. XRCC1, a key player in base excision repair, single strand break repair, nucleotide excision repair and alternative non-homologous end joining, interacts with PARP1 and coordinates DNA repair. ATR, ATM and Wee1 have essential roles in DNA repair and cell cycle regulation.

Methods:

Highly selective inhibitors of ATR (AZD6738), ATM (AZ31) and Wee1 (AZD1775) either alone or in combination with olaparib were tested for synthetic lethality in XRCC1 deficient TNBC or HeLa cells. Clinicopathological significance of ATR, ATM or Wee1 co-expression in XRCC1 proficient or deficient tumours was evaluated in a large cohort of 1650 human breast cancers.

Results:

ATR (AZD6738), ATM (AZ31) or Wee1 (AZD1775) monotherapy was selectively toxic in XRCC1 deficient cells. Selective synergistic toxicity was evident when olaparib was combined with AZD6738, AZ31 or AZD1775. The most potent synergistic interaction was evident with the AZD6738 and olaparib combination therapy. In clinical cohorts, ATR, ATM or Wee1 overexpression in XRCC1 deficient breast cancer was associated with poor outcomes.

Conclusion:

XRCC1 stratified DNA repair targeted combinatorial approach is feasible and warrants further clinical evaluation in breast cancer.

Monoclonal Antibody Targeting Sialyl-di-Lewisa-Containing Internalizing and Noninternalizing Glycoproteins with Cancer Immunotherapy Development Potential

Tumor glycans constitute attractive targets for therapeutic antibodies. The sialylated glycocalyx plays a prominent role in cancer progression and immune evasion. Here, we describe the characterization of the mAb, FG129, which targets tumor-associated sialylated glycan, and demonstrate its potential for multimodal cancer therapy. FG129, obtained through BALB/c mouse immunizations with liposomes containing membrane glycan extracts from the colorectal cancer cell line LS180, is an mIgG1κ that targets sialyl-di-Lewis^a-containing glycoproteins. FG129, as well as its chimeric human IgG1 variant, CH129, binds with nanomolar functional affinity to a range of colorectal, pancreatic, and gastric cancer cell lines. FG129 targets 74% (135/182) of pancreatic, 50% (46/92) of gastric, 36% (100/281) of colorectal, 27% (89/327) of ovarian, and 21% (42/201) of non-small cell lung cancers, by IHC. In our pancreatic cancer cohort, high FG129 glyco-epitope expression was significantly associated with poor prognosis (P = 0.004). Crucially, the glyco-epitope displays limited normal tissue distribution, with FG129 binding weakly to a small percentage of cells within gallbladder, ileum, liver, esophagus, pancreas, and thyroid tissues. Owing to glyco-epitope internalization, we validated payload delivery by CH129 through monomethyl auristatin E (MMAE) or maytansinoid (DM1 and DM4) conjugation. All three CH129 drug conjugates killed high-binding colorectal and pancreatic cancer cell lines with (sub)nanomolar potency, coinciding with significant in vivo xenograft tumor control by CH129-vcMMAE. CH129, with its restricted normal tissue distribution, avid tumor binding, and efficient payload delivery, is a promising candidate for the treatment of sialyl-di-Lewis^a-expressing solid tumors, as an antibody-drug conjugate or as an alternative cancer immunotherapy modality.

PARP1 blockade is synthetically lethal in XRCC1 deficient sporadic epithelial ovarian cancers

PARP1 inhibitor (Niraparib, Olaparib, Rucaparib) maintenance therapy improves progression-free survival in platinum sensitive sporadic epithelial ovarian cancers. However, biomarkers of response to PARPi therapy is yet to be clearly defined. XRCC1, a scaffolding protein, interacts with PARP1 during BER and SSBR. In a large clinical cohort of 525 sporadic ovarian cancers, high XRCC1 or high PARP1 protein levels was not only associated with aggressive phenotypes but was also significantly linked with poor progression-free survival (p = 0.048 & p = 0.001 respectively) and poor ovarian cancer-specific survival (p = 0.020 & p = 0.008 respectively). Pre-clinically, Olaparib and Talazoparib therapy were selectively toxic in XRCC1 deficient or knock-out platinum sensitive ovarian cancer cells in 2D and 3D models. Increased sensitivity was associated with DNA double-strand break accumulation, cell cycle arrest and apoptotic cell accumulation. We conclude that XRCC1 deficiency predicts sensitivity to PARP inhibitor therapy. PARP1 targeting is a promising new approach in XRCC1 deficient ovarian cancers.

ERCC1 Is a Predictor of Anthracycline Resistance and Taxane Sensitivity in Early Stage or Locally Advanced Breast Cancers

Genomic instability could be a beneficial predictor for anthracycline or taxane chemotherapy. We interrogated 188 DNA repair genes in the METABRIC cohort (n = 1980) to identify genes that influence overall survival (OS). We then evaluated the clinicopathological significance of ERCC1 in early stage breast cancer (BC) (mRNA expression (n = 4640) and protein level, n = 1650 (test set), and n = 252 (validation)) and in locally advanced BC (LABC) (mRNA expression, test set (n = 2340) and validation (TOP clinical trial cohort, n = 120); and protein level (n = 120)). In the multivariate model, ERCC1 was independently associated with OS in the METABRIC cohort. In ER+ tumours, low ERCC1 transcript or protein level was associated with increased distant relapse risk (DRR). In ER−tumours, low ERCC1 transcript or protein level was linked to decreased DRR, especially in patients who received anthracycline chemotherapy. In LABC patients who received neoadjuvant anthracycline, low ERCC1 transcript was associated with higher pCR (pathological complete response) and decreased DRR. However, in patients with ER−tumours who received additional neoadjuvant taxane, high ERCC1 transcript was associated with a higher pCR and decreased DRR. High ERCC1 transcript was also linked to decreased DRR in ER+ LABC that received additional neoadjuvant taxane. ERCC1 based stratification is an attractive strategy for breast cancers.

Dealing with statutory bodies under the Mental Healthcare Act 2017

India has an enormous burden of mental illness. In spite of the recognition of this population of people living with mental illness, the treatment gap continues to be about 83%. In order to meet this vast unmet need and in the view of aligning the mental health legislation with the international standards and the UN-Convention on the Rights of Persons with Disabilities, the Mental Healthcare Act 2017 was passed and enforced recently. The provisions in the act have been controversial from its conception. Now after the enforcement of the act, all mental health professionals (MHPs) have a legal binding to follow the provisions in the law. The MHPs are accountable to the statutory bodies - the Central Mental Health Authority, State Mental Health Authority (SMHA), Mental Health Review Board, and finally, the High Court or the Supreme Court. The Mental Healthcare Act (MHCA) and relevant articles/documents obtained pertaining to MHCA and their evaluation were reviewed, the major focus being on the role of statutory/regulatory bodies. Furthermore, an attempt was made to summarize the previous experiences in inspection of mental health establishments by SMHA of Karnataka. We concluded that the MHCA will have both positive and negative aspects. Many of the provisions in the law may appear unclear and unrealistic by many practitioners. However, it becomes precautionary for the MHPs to be well equipped with the MHCA and be acquainted with the requirements of the statutory bodies for ensuring a safe practice. The outcome of the implementation of the act will become evident only with time.

Ramucirumab with cisplatin and fluoropyrimidine as first-line therapy in patients with metastatic gastric or junctional adenocarcinoma (RAINFALL): a double-blind, randomised, placebo-controlled, phase 3 trial

BACKGROUND

VEGF and VEGF receptor 2 (VEGFR-2)-mediated signalling and angiogenesis can contribute to the pathogenesis and progression of gastric cancer. We aimed to assess whether the addition of ramucirumab, a VEGFR-2 antagonist monoclonal antibody, to first-line chemotherapy improves outcomes in patients with metastatic gastric or gastro-oesophageal junction adenocarcinoma.

METHODS

For this double-blind, randomised, placebo-controlled, phase 3 trial done at 126 centres in 20 countries, we recruited patients aged 18 years or older with metastatic, HER2-negative gastric or gastro-oesophageal junction adenocarcinoma, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and adequate organ function. Eligible patients were randomly assigned (1:1) with an interactive web response system to receive cisplatin (80 mg/m2, on the first day) plus capecitabine (1000 mg/m2, twice daily for 14 days), every 21 days, and either ramucirumab (8 mg/kg) or placebo on days 1 and 8, every 21 days. 5-Fluorouracil (800 mg/m2 intravenous infusion on days 1-5) was permitted in patients unable to take capecitabine. The primary endpoint was investigator-assessed progression-free survival, analysed by intention to treat in the first 508 patients. We did a sensitivity analysis of the primary endpoint, including a central review of CT scans. Overall survival was a key secondary endpoint. This study is registered with ClinicalTrials.gov, number NCT02314117.

FINDINGS

Between Jan 28, 2015, and Sept 16, 2016, 645 patients were randomly assigned to receive ramucirumab plus fluoropyrimidine and cisplatin (n=326) or placebo plus fluoropyrimidine and cisplatin (n=319). Investigator-assessed progression-free survival was significantly longer in the ramucirumab group than the placebo group (hazard ratio [HR] 0·753, 95% CI 0·607-0·935, p=0·0106; median progression-free survival 5·7 months [5·5-6·5] vs 5·4 months [4·5-5·7]). A sensitivity analysis based on central independent review of the radiological images did not corroborate the investigator-assessed difference in progression-free survival (HR 0·961, 95% CI 0·768-1·203, p=0·74). There was no difference in overall survival between groups (0·962, 0·801-1·156, p=0·6757; median overall survival 11·2 months [9·9-11·9] in the ramucirumab group vs 10·7 months [9·5-11·9] in the placebo group). The most common grade 3-4 adverse events were neutropenia (85 [26%] of 323 patients in the ramucirumab group vs 85 [27%] of 315 in the placebo group), anaemia (39 [12%] vs 44 [14%]), and hypertension (32 [10%] vs 5 [2%]). The incidence of any-grade serious adverse events was 160 (50%) of 323 patients in the ramucirumab group and 149 (47%) of 315 patients in the placebo group. The most common serious adverse events were vomiting (14 [4%] in the ramucirumab group vs 21 [7%] in the placebo group) and diarrhoea (11 [3%] vs 19 [6%]). There were seven deaths in each group, either during study treatment or within 30 days of discontinuing study treatment, which were the result of treatment-related adverse events. In the ramucirumab group, these adverse events were acute kidney injury, cardiac arrest, gastric haemorrhage, peritonitis, pneumothorax, septic shock, and sudden death (n=1 of each). In the placebo group, these adverse events were cerebrovascular accident (n=1), multiple organ dysfunction syndrome (n=2), pulmonary embolism (n=2), sepsis (n=1), and small intestine perforation (n=1).

INTERPRETATION

Although the primary analysis for progression-free survival was statistically significant, this outcome was not confirmed in a sensitivity analysis of progression-free survival by central independent review, and did not improve overall survival. Therefore, the addition of ramucirumab to cisplatin plus fluoropyrimidine chemotherapy is not recommended as first-line treatment for this patient population.

FUNDING

Eli Lilly and Company.

Clinicopathological significance of ataxia telangiectasia-mutated (ATM) kinase and ataxia telangiectasia-mutated and Rad3-related (ATR) kinase in MYC overexpressed breast cancers

PURPOSE

MYC transcription factor has critical roles in cell growth, proliferation, metabolism, differentiation, transformation and angiogenesis. MYC overexpression is seen in about 15% of breast cancers and linked to aggressive phenotypes. MYC overexpression also induces oxidative stress and replication stress in cells. ATM signalling and ATR-mediated signalling are critical for MYC-induced DNA damage response. Whether ATM and ATR expressions influence clinical outcomes in MYC overexpressed breast cancers is unknown.

METHODS

We investigated ATM, ATR and MYC at the transcriptional level [Molecular Taxonomy of Breast Cancer International Consortium cohort (n = 1950)] and at the protein level in the Nottingham series comprising 1650 breast tumours. We correlated ATM, ATR and MYC expressions to clinicopathological features and survival outcomes.

RESULTS

In MYC over expressed tumours, high ATR or low ATM levels were associated with aggressive breast cancer features such as higher tumour grade, de-differentiation, pleomorphism, high mitotic index, high-risk Nottingham Prognostic Index, triple negative and basal-like breast cancers (all adjusted p values < 0.05). Tumours with low ATM or high ATR levels in conjunction with MYC overexpression also have worse overall breast cancer-specific survival (BCSS) (p value < 0.05).

CONCLUSIONS

We conclude that ATR/ATM-directed stratification and personalisation of therapy may be feasible in MYC overexpressed breast cancer.

The mTOR downstream regulator (p-4EBP1) is a novel independent prognostic marker in ovarian cancer

Ovarian cancer is associated with the highest mortality rate among gynaecologic malignancies. There is a need to refine the classification of ovarian cancer and identify novel targets. The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. This study aims to investigate the prognostic role of p-mTOR and its major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. p-mTOR, p-4EBP1 and p-P70S6K protein expression was assessed on 195 consecutive ovarian epithelial cancers and correlated to clinicopathological features and survival. We found that high cytoplasmic expression of p-4EBP1 and p-P70S6K was associated with a serous type carcinoma (p = .005) and an advanced FIGO stage (p = .012), respectively. Univariate outcome analysis showed an inverse association between a high expression of p-4EBP1 expression and overall ovarian cancer survival (OS; p = .005) and progression-free survival (PFS; p = .005). p-P70S6K showed an inverse association with PFS (p = .001). Multivariate analyses indicated that p-4EBP1 was an independent predictor of both OS and PFS (p = .016 and p = .041, respectively). Therefore, we concluded that p-4EBP1 high protein expression is an independent predictor of outcome in ovarian cancer patients. Therefore, it could be used as a potential biomarker for prognostic stratification and treatment decisions. Impact statement What is already known on this subject? The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. To-date, very limited knowledge is known about the importance of mTOR major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. What do the results of this study add? In this study, we have provided further evidence of the adverse prognostic behaviour associated with the positive expression of p-mTOR and its major downstream effectors. Moreover and by performing multivariate analysis, we for the first time have proved that p-4EBP1 is an independent predictor of clinical outcome in ovarian cancer. What are the implications of these findings for clinical practice and/or further research? p-4EBP1 could be used as a potential biomarker for prognostic stratification and treatment decisions in ovarian cancer management.

Targeting PARP1 in XRCC1-Deficient Sporadic Invasive Breast Cancer or Preinvasive Ductal Carcinoma In Situ Induces Synthetic Lethality and Chemoprevention

: Targeting PARP1 for synthetic lethality is a new strategy for breast cancers harboring germline mutations in BRCA. However, these mutations are rare, and reactivation of BRCA-mediated pathways may result in eventual resistance to PARP1 inhibitor therapy. Alternative synthetic lethality approaches targeting more common sporadic breast cancers and preinvasive ductal carcinoma in situ (DCIS) are desirable. Here we show that downregulation of XRCC1, which interacts with PARP1 and coordinates base excision repair, is an early event in human breast cancer pathogenesis. XRCC1-deficient DCIS were aggressive and associated with increased risk of local recurrence. Human invasive breast cancers deficient in XRCC1 and expressing high PARP1 levels also manifested aggressive features and poor outcome. The PARP1 inhibitor olaparib was synthetically lethal in XRCC1-deficient DCIS and invasive breast cancer cells. We conclude that targeting PARP1 is an attractive strategy for synthetic lethality and chemoprevention in XRCC1-deficient breast cancers, including preinvasive DCIS. SIGNIFICANCE: These findings show that loss of XRCC1, which is associated with more malignant DCIS, can be exploited by PARP inhibition, suggesting its application as a promising therapeutic and chemoprevention strategy in XRCC1-deficient tumor cells.

LY2495655, an antimyostatin antibody, in pancreatic cancer: a randomized, phase 2 trial

BACKGROUND

Cachexia is a formidable clinical challenge in pancreatic cancer. We assessed LY2495655 (antimyostatin antibody) plus standard-of-care chemotherapy in pancreatic cancer using cachexia status as a stratifier.

METHODS

In this randomized, phase 2 trial, patients with stage II-IV pancreatic cancer were randomized to 300 mg LY2495655, 100 mg LY2495655, or placebo, plus physician-choice chemotherapy from a prespecified list of standard-of-care regimens for first and later lines of care. Investigational treatment was continued during second-line treatment. The primary endpoint was overall survival.

RESULTS

Overall, 125 patients were randomized. In August 2014, 300 mg LY2495655 was terminated due to imbalance in death rates between the treatment arms; in January 2015, 100 mg LY2495655 treatment was terminated due to futility. LY2495655 did not improve overall survival: the hazard ratio was 1.70 (90% confidence interval, 1.1-2.7) for 300 mg vs. placebo and 1.3 (0.82-2.1) for 100 mg vs. placebo (recommended doses). Progression-free survival results were consistent with the overall survival results. A numerically higher hazard ratio was observed in patients with weight loss (WL) of ≥5% (cachexia) than with <5% WL within 6 months before randomization. Subgroup analyses for patients stratified by WL in the 6 months preceding enrollment suggested that functional responses to LY2495655 (either dose) may have been superior in patients with <5% WL vs. patients with ≥5% WL. Among possibly drug-related adverse events, fatigue, diarrhoea, and anorexia were more common in LY2495655-treated than in placebo-treated patients.

CONCLUSIONS

In the intention-to-treat analysis, LY2495655 did not confer clinical benefit in pancreatic cancer. Our data highlight the importance of assessing survival when investigating therapeutic management of cachexia and support the use of WL as a stratifier (independent of performance status).

Abstract A18: Predictive and prognostic significance of RECQ1 expression in breast cancer

RECQ1, also known as RECQL or RECQL1, is critical for DNA replication and repair. Germline mutations in the RECQ1 gene predispose to hereditary breast cancers. Overexpression of RECQ1 has been reported in a variety of human cancers including breast cancers. Our recent studies have identified a novel function of RECQ1 in regulation of gene expression and suggest that RECQ1 contributes to tumor development and progression, in part through regulating the expression of key genes that promote invasion and metastasis of cancer cells. Additionally, our data suggest that RECQ1 expression may serve as a predictive marker of clinical outcome. Preclinically RECQ1 depletion in breast cancer cells resulted in doxorubicin sensitivity, DNA double-strand breaks accumulation, S-phase cell cycle arrest, and apoptosis. Utilizing METABRIC cohort to investigate clinicopathologic significance of altered RECQ1 expression in sporadic breast cancers, we found that in ER-positive tumors that received endocrine therapy, low RECQ1 was associated with poor survival; in contrast, in ER-negative tumors that received adjuvant anthracycline-based chemotherapy, high RECQ1 was associated with poor disease-free survival. Taken together, our data provide the first preliminary evidence that RECQ1 is a promising prognostic and predictive biomarker in breast cancers.

Citation Format: Swetha Parvathaneni, Xing Lu, Xiao Ling Li, Ritu Chaudhary, Ashish Lal, Srinivasan Madhusudan, Sudha Sharma. Predictive and prognostic significance of RECQ1 expression in breast cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A18.

Circulating biomarkers during treatment in patients with advanced biliary tract cancer receiving cediranib in the UK ABC-03 trial

BACKGROUND

Advanced biliary tract cancer (ABC) has a poor prognosis. Cediranib, in addition to cisplatin/gemcitabine [CisGem], improved the response rate, but did not improve the progression-free survival (PFS) in the ABC-03 study. Minimally invasive biomarkers predictive of cediranib benefit may improve patient outcomes.

METHODS

Changes in 15 circulating plasma angiogenesis or inflammatory-related proteins and cytokeratin-18 (CK18), measured at baseline and during therapy until disease progression, were correlated with overall survival (OS) using time-varying covariate Cox models (TVC).

RESULTS

Samples were available from n = 117/124 (94%) patients. Circulating Ang1&2, FGFb, PDGFbb, VEGFC, VEGFR1 and CK18 decreased as a result of the therapy, independent of treatment with cediranib. Circulating VEGFR2 and Tie2 were preferentially reduced by cediranib. Patients with increasing levels of VEGFA at any time had a worse PFS and OS; this detrimental effect was attenuated in patients receiving cediranib. TVC analysis revealed CK18 and VEGFR2 increases correlated with poorer OS in all patients (P < 0.001 and P = 0.02, respectively).

CONCLUSIONS

Rising circulating VEGFA levels in patients with ABC, treated with CisGem, are associated with worse PFS and OS, not seen in patients receiving cediranib. Rising levels of markers of tumour burden (CK18) and potential resistance (VEGFR2) are associated with worse outcomes and warrant validation.

The relationship of CDK18 expression in breast cancer to clinicopathological parameters and therapeutic response

Background

Cyclin-Dependent Kinases (CDKs) are established anti-cancer drug targets and a new generation of CDK inhibitors are providing clinical benefits to a sub-set of breast cancer patients. We have recently shown that human CDK18 promotes efficient cellular responses to replication stress. In the current study, we have investigated the clinicopathological and functional significance of CDK18 expression levels in breast cancers.

Results

High CDK18 protein expression was associated with a triple negative and basal-like phenotype (p = 0.021 and 0.027 respectively) as well as improved patient survival, which was particularly significant in ER negative breast cancers (n = 594, Log Rank 6.724, p = 0.01) and those treated with chemotherapy (n = 270, Log Rank 4.575, p = 0.03). In agreement with these clinical findings, breast cancer cells genetically manipulated using a dCRISPR approach to express high levels of endogenous CDK18 exhibited an increased sensitivity to replication stress-inducing chemotherapeutic agents, as a consequence to defective replication stress signalling at the molecular level.

Conclusions

These data reveal that CDK18 protein levels may predict breast cancer disease progression and response to chemotherapy, and provide further rationale for potential targeting of CDK18 as part of novel anti-cancer strategies for human cancers.

Materials and Methods

CDK18 protein expression was evaluated in 1650 breast cancers and correlated to clinicopathological parameters and survival outcomes. Similar analyses were carried out for genetic and transcriptomic changes in CDK18 within several publically available breast cancer cohorts. Additionally, we used a deactivated CRISPR/Cas9 approach (dCRISPR) to elucidate the molecular consequences of heightened endogenous CDK18 expression within breast cancer cells.